1	//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===//
2	//
3	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4	// See https://llvm.org/LICENSE.txt for license information.
5	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6	//
7	//===----------------------------------------------------------------------===//
8	//
9	// This file implements the Expr constant evaluator.
10	//
11	// Constant expression evaluation produces four main results:
12	//
13	// * A success/failure flag indicating whether constant folding was successful.
14	// This is the 'bool' return value used by most of the code in this file. A
15	// 'false' return value indicates that constant folding has failed, and any
16	// appropriate diagnostic has already been produced.
17	//
18	// * An evaluated result, valid only if constant folding has not failed.
19	//
20	// * A flag indicating if evaluation encountered (unevaluated) side-effects.
21	// These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1),
22	// where it is possible to determine the evaluated result regardless.
23	//
24	// * A set of notes indicating why the evaluation was not a constant expression
25	// (under the C++11 / C++1y rules only, at the moment), or, if folding failed
26	// too, why the expression could not be folded.
27	//
28	// If we are checking for a potential constant expression, failure to constant
29	// fold a potential constant sub-expression will be indicated by a 'false'
30	// return value (the expression could not be folded) and no diagnostic (the
31	// expression is not necessarily non-constant).
32	//
33	//===----------------------------------------------------------------------===//
34
35	#include "ByteCode/Context.h"
36	#include "ByteCode/Frame.h"
37	#include "ByteCode/State.h"
38	#include "ExprConstShared.h"
39	#include "clang/AST/APValue.h"
40	#include "clang/AST/ASTContext.h"
41	#include "clang/AST/ASTLambda.h"
42	#include "clang/AST/Attr.h"
43	#include "clang/AST/CXXInheritance.h"
44	#include "clang/AST/CharUnits.h"
45	#include "clang/AST/CurrentSourceLocExprScope.h"
46	#include "clang/AST/Expr.h"
47	#include "clang/AST/OSLog.h"
48	#include "clang/AST/OptionalDiagnostic.h"
49	#include "clang/AST/RecordLayout.h"
50	#include "clang/AST/StmtVisitor.h"
51	#include "clang/AST/TypeLoc.h"
52	#include "clang/Basic/Builtins.h"
53	#include "clang/Basic/DiagnosticSema.h"
54	#include "clang/Basic/TargetBuiltins.h"
55	#include "clang/Basic/TargetInfo.h"
56	#include "llvm/ADT/APFixedPoint.h"
57	#include "llvm/ADT/Sequence.h"
58	#include "llvm/ADT/SmallBitVector.h"
59	#include "llvm/ADT/StringExtras.h"
60	#include "llvm/Support/Casting.h"
61	#include "llvm/Support/Debug.h"
62	#include "llvm/Support/SaveAndRestore.h"
63	#include "llvm/Support/SipHash.h"
64	#include "llvm/Support/TimeProfiler.h"
65	#include "llvm/Support/raw_ostream.h"
66	#include <cstring>
67	#include <functional>
68	#include <optional>
69
70	#define DEBUG_TYPE "exprconstant"
71
72	using namespace clang;
73	using llvm::APFixedPoint;
74	using llvm::APInt;
75	using llvm::APSInt;
76	using llvm::APFloat;
77	using llvm::FixedPointSemantics;
78
79	namespace {
80	struct LValue;
81	class CallStackFrame;
82	class EvalInfo;
83
84	using SourceLocExprScopeGuard =
85	CurrentSourceLocExprScope::SourceLocExprScopeGuard;
86
87	static QualType getType(APValue::LValueBase B) {
88	return B.getType();
89	}
90
91	/// Get an LValue path entry, which is known to not be an array index, as a
92	/// field declaration.
93	static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
94	return dyn_cast_or_null<FieldDecl>(Val: E.getAsBaseOrMember().getPointer());
95	}
96	/// Get an LValue path entry, which is known to not be an array index, as a
97	/// base class declaration.
98	static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
99	return dyn_cast_or_null<CXXRecordDecl>(Val: E.getAsBaseOrMember().getPointer());
100	}
101	/// Determine whether this LValue path entry for a base class names a virtual
102	/// base class.
103	static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
104	return E.getAsBaseOrMember().getInt();
105	}
106
107	/// Given an expression, determine the type used to store the result of
108	/// evaluating that expression.
109	static QualType getStorageType(const ASTContext &Ctx, const Expr *E) {
110	if (E->isPRValue())
111	return E->getType();
112	return Ctx.getLValueReferenceType(T: E->getType());
113	}
114
115	/// Given a CallExpr, try to get the alloc_size attribute. May return null.
116	static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
117	if (const FunctionDecl *DirectCallee = CE->getDirectCallee())
118	return DirectCallee->getAttr<AllocSizeAttr>();
119	if (const Decl *IndirectCallee = CE->getCalleeDecl())
120	return IndirectCallee->getAttr<AllocSizeAttr>();
121	return nullptr;
122	}
123
124	/// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
125	/// This will look through a single cast.
126	///
127	/// Returns null if we couldn't unwrap a function with alloc_size.
128	static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
129	if (!E->getType()->isPointerType())
130	return nullptr;
131
132	E = E->IgnoreParens();
133	// If we're doing a variable assignment from e.g. malloc(N), there will
134	// probably be a cast of some kind. In exotic cases, we might also see a
135	// top-level ExprWithCleanups. Ignore them either way.
136	if (const auto *FE = dyn_cast<FullExpr>(Val: E))
137	E = FE->getSubExpr()->IgnoreParens();
138
139	if (const auto *Cast = dyn_cast<CastExpr>(Val: E))
140	E = Cast->getSubExpr()->IgnoreParens();
141
142	if (const auto *CE = dyn_cast<CallExpr>(E))
143	return getAllocSizeAttr(CE) ? CE : nullptr;
144	return nullptr;
145	}
146
147	/// Determines whether or not the given Base contains a call to a function
148	/// with the alloc_size attribute.
149	static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
150	const auto *E = Base.dyn_cast<const Expr *>();
151	return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
152	}
153
154	/// Determines whether the given kind of constant expression is only ever
155	/// used for name mangling. If so, it's permitted to reference things that we
156	/// can't generate code for (in particular, dllimported functions).
157	static bool isForManglingOnly(ConstantExprKind Kind) {
158	switch (Kind) {
159	case ConstantExprKind::Normal:
160	case ConstantExprKind::ClassTemplateArgument:
161	case ConstantExprKind::ImmediateInvocation:
162	// Note that non-type template arguments of class type are emitted as
163	// template parameter objects.
164	return false;
165
166	case ConstantExprKind::NonClassTemplateArgument:
167	return true;
168	}
169	llvm_unreachable("unknown ConstantExprKind");
170	}
171
172	static bool isTemplateArgument(ConstantExprKind Kind) {
173	switch (Kind) {
174	case ConstantExprKind::Normal:
175	case ConstantExprKind::ImmediateInvocation:
176	return false;
177
178	case ConstantExprKind::ClassTemplateArgument:
179	case ConstantExprKind::NonClassTemplateArgument:
180	return true;
181	}
182	llvm_unreachable("unknown ConstantExprKind");
183	}
184
185	/// The bound to claim that an array of unknown bound has.
186	/// The value in MostDerivedArraySize is undefined in this case. So, set it
187	/// to an arbitrary value that's likely to loudly break things if it's used.
188	static const uint64_t AssumedSizeForUnsizedArray =
189	std::numeric_limits<uint64_t>::max() / 2;
190
191	/// Determines if an LValue with the given LValueBase will have an unsized
192	/// array in its designator.
193	/// Find the path length and type of the most-derived subobject in the given
194	/// path, and find the size of the containing array, if any.
195	static unsigned
196	findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
197	ArrayRef<APValue::LValuePathEntry> Path,
198	uint64_t &ArraySize, QualType &Type, bool &IsArray,
199	bool &FirstEntryIsUnsizedArray) {
200	// This only accepts LValueBases from APValues, and APValues don't support
201	// arrays that lack size info.
202	assert(!isBaseAnAllocSizeCall(Base) &&
203	"Unsized arrays shouldn't appear here");
204	unsigned MostDerivedLength = 0;
205	Type = getType(B: Base);
206
207	for (unsigned I = 0, N = Path.size(); I != N; ++I) {
208	if (Type->isArrayType()) {
209	const ArrayType *AT = Ctx.getAsArrayType(T: Type);
210	Type = AT->getElementType();
211	MostDerivedLength = I + 1;
212	IsArray = true;
213
214	if (auto *CAT = dyn_cast<ConstantArrayType>(Val: AT)) {
215	ArraySize = CAT->getZExtSize();
216	} else {
217	assert(I == 0 && "unexpected unsized array designator");
218	FirstEntryIsUnsizedArray = true;
219	ArraySize = AssumedSizeForUnsizedArray;
220	}
221	} else if (Type->isAnyComplexType()) {
222	const ComplexType *CT = Type->castAs<ComplexType>();
223	Type = CT->getElementType();
224	ArraySize = 2;
225	MostDerivedLength = I + 1;
226	IsArray = true;
227	} else if (const auto *VT = Type->getAs<VectorType>()) {
228	Type = VT->getElementType();
229	ArraySize = VT->getNumElements();
230	MostDerivedLength = I + 1;
231	IsArray = true;
232	} else if (const FieldDecl *FD = getAsField(E: Path[I])) {
233	Type = FD->getType();
234	ArraySize = 0;
235	MostDerivedLength = I + 1;
236	IsArray = false;
237	} else {
238	// Path[I] describes a base class.
239	ArraySize = 0;
240	IsArray = false;
241	}
242	}
243	return MostDerivedLength;
244	}
245
246	/// A path from a glvalue to a subobject of that glvalue.
247	struct SubobjectDesignator {
248	/// True if the subobject was named in a manner not supported by C++11. Such
249	/// lvalues can still be folded, but they are not core constant expressions
250	/// and we cannot perform lvalue-to-rvalue conversions on them.
251	LLVM_PREFERRED_TYPE(bool)
252	unsigned Invalid : 1;
253
254	/// Is this a pointer one past the end of an object?
255	LLVM_PREFERRED_TYPE(bool)
256	unsigned IsOnePastTheEnd : 1;
257
258	/// Indicator of whether the first entry is an unsized array.
259	LLVM_PREFERRED_TYPE(bool)
260	unsigned FirstEntryIsAnUnsizedArray : 1;
261
262	/// Indicator of whether the most-derived object is an array element.
263	LLVM_PREFERRED_TYPE(bool)
264	unsigned MostDerivedIsArrayElement : 1;
265
266	/// The length of the path to the most-derived object of which this is a
267	/// subobject.
268	unsigned MostDerivedPathLength : 28;
269
270	/// The size of the array of which the most-derived object is an element.
271	/// This will always be 0 if the most-derived object is not an array
272	/// element. 0 is not an indicator of whether or not the most-derived object
273	/// is an array, however, because 0-length arrays are allowed.
274	///
275	/// If the current array is an unsized array, the value of this is
276	/// undefined.
277	uint64_t MostDerivedArraySize;
278	/// The type of the most derived object referred to by this address.
279	QualType MostDerivedType;
280
281	typedef APValue::LValuePathEntry PathEntry;
282
283	/// The entries on the path from the glvalue to the designated subobject.
284	SmallVector<PathEntry, 8> Entries;
285
286	SubobjectDesignator() : Invalid(true) {}
287
288	explicit SubobjectDesignator(QualType T)
289	: Invalid(false), IsOnePastTheEnd(false),
290	FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
291	MostDerivedPathLength(0), MostDerivedArraySize(0),
292	MostDerivedType(T) {}
293
294	SubobjectDesignator(ASTContext &Ctx, const APValue &V)
295	: Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
296	FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
297	MostDerivedPathLength(0), MostDerivedArraySize(0) {
298	assert(V.isLValue() && "Non-LValue used to make an LValue designator?");
299	if (!Invalid) {
300	IsOnePastTheEnd = V.isLValueOnePastTheEnd();
301	llvm::append_range(C&: Entries, R: V.getLValuePath());
302	if (V.getLValueBase()) {
303	bool IsArray = false;
304	bool FirstIsUnsizedArray = false;
305	MostDerivedPathLength = findMostDerivedSubobject(
306	Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
307	MostDerivedType, IsArray, FirstIsUnsizedArray);
308	MostDerivedIsArrayElement = IsArray;
309	FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
310	}
311	}
312	}
313
314	void truncate(ASTContext &Ctx, APValue::LValueBase Base,
315	unsigned NewLength) {
316	if (Invalid)
317	return;
318
319	assert(Base && "cannot truncate path for null pointer");
320	assert(NewLength <= Entries.size() && "not a truncation");
321
322	if (NewLength == Entries.size())
323	return;
324	Entries.resize(N: NewLength);
325
326	bool IsArray = false;
327	bool FirstIsUnsizedArray = false;
328	MostDerivedPathLength = findMostDerivedSubobject(
329	Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray,
330	FirstIsUnsizedArray);
331	MostDerivedIsArrayElement = IsArray;
332	FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
333	}
334
335	void setInvalid() {
336	Invalid = true;
337	Entries.clear();
338	}
339
340	/// Determine whether the most derived subobject is an array without a
341	/// known bound.
342	bool isMostDerivedAnUnsizedArray() const {
343	assert(!Invalid && "Calling this makes no sense on invalid designators");
344	return Entries.size() == 1 && FirstEntryIsAnUnsizedArray;
345	}
346
347	/// Determine what the most derived array's size is. Results in an assertion
348	/// failure if the most derived array lacks a size.
349	uint64_t getMostDerivedArraySize() const {
350	assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size");
351	return MostDerivedArraySize;
352	}
353
354	/// Determine whether this is a one-past-the-end pointer.
355	bool isOnePastTheEnd() const {
356	assert(!Invalid);
357	if (IsOnePastTheEnd)
358	return true;
359	if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement &&
360	Entries[MostDerivedPathLength - 1].getAsArrayIndex() ==
361	MostDerivedArraySize)
362	return true;
363	return false;
364	}
365
366	/// Get the range of valid index adjustments in the form
367	/// {maximum value that can be subtracted from this pointer,
368	/// maximum value that can be added to this pointer}
369	std::pair<uint64_t, uint64_t> validIndexAdjustments() {
370	if (Invalid || isMostDerivedAnUnsizedArray())
371	return {0, 0};
372
373	// [expr.add]p4: For the purposes of these operators, a pointer to a
374	// nonarray object behaves the same as a pointer to the first element of
375	// an array of length one with the type of the object as its element type.
376	bool IsArray = MostDerivedPathLength == Entries.size() &&
377	MostDerivedIsArrayElement;
378	uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
379	: (uint64_t)IsOnePastTheEnd;
380	uint64_t ArraySize =
381	IsArray ? getMostDerivedArraySize() : (uint64_t)1;
382	return {ArrayIndex, ArraySize - ArrayIndex};
383	}
384
385	/// Check that this refers to a valid subobject.
386	bool isValidSubobject() const {
387	if (Invalid)
388	return false;
389	return !isOnePastTheEnd();
390	}
391	/// Check that this refers to a valid subobject, and if not, produce a
392	/// relevant diagnostic and set the designator as invalid.
393	bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);
394
395	/// Get the type of the designated object.
396	QualType getType(ASTContext &Ctx) const {
397	assert(!Invalid && "invalid designator has no subobject type");
398	return MostDerivedPathLength == Entries.size()
399	? MostDerivedType
400	: Ctx.getRecordType(getAsBaseClass(Entries.back()));
401	}
402
403	/// Update this designator to refer to the first element within this array.
404	void addArrayUnchecked(const ConstantArrayType *CAT) {
405	Entries.push_back(Elt: PathEntry::ArrayIndex(Index: 0));
406
407	// This is a most-derived object.
408	MostDerivedType = CAT->getElementType();
409	MostDerivedIsArrayElement = true;
410	MostDerivedArraySize = CAT->getZExtSize();
411	MostDerivedPathLength = Entries.size();
412	}
413	/// Update this designator to refer to the first element within the array of
414	/// elements of type T. This is an array of unknown size.
415	void addUnsizedArrayUnchecked(QualType ElemTy) {
416	Entries.push_back(Elt: PathEntry::ArrayIndex(Index: 0));
417
418	MostDerivedType = ElemTy;
419	MostDerivedIsArrayElement = true;
420	// The value in MostDerivedArraySize is undefined in this case. So, set it
421	// to an arbitrary value that's likely to loudly break things if it's
422	// used.
423	MostDerivedArraySize = AssumedSizeForUnsizedArray;
424	MostDerivedPathLength = Entries.size();
425	}
426	/// Update this designator to refer to the given base or member of this
427	/// object.
428	void addDeclUnchecked(const Decl *D, bool Virtual = false) {
429	Entries.push_back(Elt: APValue::BaseOrMemberType(D, Virtual));
430
431	// If this isn't a base class, it's a new most-derived object.
432	if (const FieldDecl *FD = dyn_cast<FieldDecl>(Val: D)) {
433	MostDerivedType = FD->getType();
434	MostDerivedIsArrayElement = false;
435	MostDerivedArraySize = 0;
436	MostDerivedPathLength = Entries.size();
437	}
438	}
439	/// Update this designator to refer to the given complex component.
440	void addComplexUnchecked(QualType EltTy, bool Imag) {
441	Entries.push_back(Elt: PathEntry::ArrayIndex(Index: Imag));
442
443	// This is technically a most-derived object, though in practice this
444	// is unlikely to matter.
445	MostDerivedType = EltTy;
446	MostDerivedIsArrayElement = true;
447	MostDerivedArraySize = 2;
448	MostDerivedPathLength = Entries.size();
449	}
450
451	void addVectorElementUnchecked(QualType EltTy, uint64_t Size,
452	uint64_t Idx) {
453	Entries.push_back(Elt: PathEntry::ArrayIndex(Index: Idx));
454	MostDerivedType = EltTy;
455	MostDerivedPathLength = Entries.size();
456	MostDerivedArraySize = 0;
457	MostDerivedIsArrayElement = false;
458	}
459
460	void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
461	void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
462	const APSInt &N);
463	/// Add N to the address of this subobject.
464	void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
465	if (Invalid || !N) return;
466	uint64_t TruncatedN = N.extOrTrunc(width: 64).getZExtValue();
467	if (isMostDerivedAnUnsizedArray()) {
468	diagnoseUnsizedArrayPointerArithmetic(Info, E);
469	// Can't verify -- trust that the user is doing the right thing (or if
470	// not, trust that the caller will catch the bad behavior).
471	// FIXME: Should we reject if this overflows, at least?
472	Entries.back() = PathEntry::ArrayIndex(
473	Index: Entries.back().getAsArrayIndex() + TruncatedN);
474	return;
475	}
476
477	// [expr.add]p4: For the purposes of these operators, a pointer to a
478	// nonarray object behaves the same as a pointer to the first element of
479	// an array of length one with the type of the object as its element type.
480	bool IsArray = MostDerivedPathLength == Entries.size() &&
481	MostDerivedIsArrayElement;
482	uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
483	: (uint64_t)IsOnePastTheEnd;
484	uint64_t ArraySize =
485	IsArray ? getMostDerivedArraySize() : (uint64_t)1;
486
487	if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) {
488	// Calculate the actual index in a wide enough type, so we can include
489	// it in the note.
490	N = N.extend(width: std::max<unsigned>(a: N.getBitWidth() + 1, b: 65));
491	(llvm::APInt&)N += ArrayIndex;
492	assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index");
493	diagnosePointerArithmetic(Info, E, N);
494	setInvalid();
495	return;
496	}
497
498	ArrayIndex += TruncatedN;
499	assert(ArrayIndex <= ArraySize &&
500	"bounds check succeeded for out-of-bounds index");
501
502	if (IsArray)
503	Entries.back() = PathEntry::ArrayIndex(Index: ArrayIndex);
504	else
505	IsOnePastTheEnd = (ArrayIndex != 0);
506	}
507	};
508
509	/// A scope at the end of which an object can need to be destroyed.
510	enum class ScopeKind {
511	Block,
512	FullExpression,
513	Call
514	};
515
516	/// A reference to a particular call and its arguments.
517	struct CallRef {
518	CallRef() : OrigCallee(), CallIndex(0), Version() {}
519	CallRef(const FunctionDecl *Callee, unsigned CallIndex, unsigned Version)
520	: OrigCallee(Callee), CallIndex(CallIndex), Version(Version) {}
521
522	explicit operator bool() const { return OrigCallee; }
523
524	/// Get the parameter that the caller initialized, corresponding to the
525	/// given parameter in the callee.
526	const ParmVarDecl *getOrigParam(const ParmVarDecl *PVD) const {
527	return OrigCallee ? OrigCallee->getParamDecl(i: PVD->getFunctionScopeIndex())
528	: PVD;
529	}
530
531	/// The callee at the point where the arguments were evaluated. This might
532	/// be different from the actual callee (a different redeclaration, or a
533	/// virtual override), but this function's parameters are the ones that
534	/// appear in the parameter map.
535	const FunctionDecl *OrigCallee;
536	/// The call index of the frame that holds the argument values.
537	unsigned CallIndex;
538	/// The version of the parameters corresponding to this call.
539	unsigned Version;
540	};
541
542	/// A stack frame in the constexpr call stack.
543	class CallStackFrame : public interp::Frame {
544	public:
545	EvalInfo &Info;
546
547	/// Parent - The caller of this stack frame.
548	CallStackFrame *Caller;
549
550	/// Callee - The function which was called.
551	const FunctionDecl *Callee;
552
553	/// This - The binding for the this pointer in this call, if any.
554	const LValue *This;
555
556	/// CallExpr - The syntactical structure of member function calls
557	const Expr *CallExpr;
558
559	/// Information on how to find the arguments to this call. Our arguments
560	/// are stored in our parent's CallStackFrame, using the ParmVarDecl* as a
561	/// key and this value as the version.
562	CallRef Arguments;
563
564	/// Source location information about the default argument or default
565	/// initializer expression we're evaluating, if any.
566	CurrentSourceLocExprScope CurSourceLocExprScope;
567
568	// Note that we intentionally use std::map here so that references to
569	// values are stable.
570	typedef std::pair<const void *, unsigned> MapKeyTy;
571	typedef std::map<MapKeyTy, APValue> MapTy;
572	/// Temporaries - Temporary lvalues materialized within this stack frame.
573	MapTy Temporaries;
574	MapTy ConstexprUnknownAPValues;
575
576	/// CallRange - The source range of the call expression for this call.
577	SourceRange CallRange;
578
579	/// Index - The call index of this call.
580	unsigned Index;
581
582	/// The stack of integers for tracking version numbers for temporaries.
583	SmallVector<unsigned, 2> TempVersionStack = {1};
584	unsigned CurTempVersion = TempVersionStack.back();
585
586	unsigned getTempVersion() const { return TempVersionStack.back(); }
587
588	void pushTempVersion() {
589	TempVersionStack.push_back(Elt: ++CurTempVersion);
590	}
591
592	void popTempVersion() {
593	TempVersionStack.pop_back();
594	}
595
596	CallRef createCall(const FunctionDecl *Callee) {
597	return {Callee, Index, ++CurTempVersion};
598	}
599
600	// FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
601	// on the overall stack usage of deeply-recursing constexpr evaluations.
602	// (We should cache this map rather than recomputing it repeatedly.)
603	// But let's try this and see how it goes; we can look into caching the map
604	// as a later change.
605
606	/// LambdaCaptureFields - Mapping from captured variables/this to
607	/// corresponding data members in the closure class.
608	llvm::DenseMap<const ValueDecl *, FieldDecl *> LambdaCaptureFields;
609	FieldDecl *LambdaThisCaptureField = nullptr;
610
611	CallStackFrame(EvalInfo &Info, SourceRange CallRange,
612	const FunctionDecl *Callee, const LValue *This,
613	const Expr *CallExpr, CallRef Arguments);
614	~CallStackFrame();
615
616	// Return the temporary for Key whose version number is Version.
617	APValue *getTemporary(const void *Key, unsigned Version) {
618	MapKeyTy KV(Key, Version);
619	auto LB = Temporaries.lower_bound(x: KV);
620	if (LB != Temporaries.end() && LB->first == KV)
621	return &LB->second;
622	return nullptr;
623	}
624
625	// Return the current temporary for Key in the map.
626	APValue *getCurrentTemporary(const void *Key) {
627	auto UB = Temporaries.upper_bound(x: MapKeyTy(Key, UINT_MAX));
628	if (UB != Temporaries.begin() && std::prev(x: UB)->first.first == Key)
629	return &std::prev(x: UB)->second;
630	return nullptr;
631	}
632
633	// Return the version number of the current temporary for Key.
634	unsigned getCurrentTemporaryVersion(const void *Key) const {
635	auto UB = Temporaries.upper_bound(x: MapKeyTy(Key, UINT_MAX));
636	if (UB != Temporaries.begin() && std::prev(x: UB)->first.first == Key)
637	return std::prev(x: UB)->first.second;
638	return 0;
639	}
640
641	/// Allocate storage for an object of type T in this stack frame.
642	/// Populates LV with a handle to the created object. Key identifies
643	/// the temporary within the stack frame, and must not be reused without
644	/// bumping the temporary version number.
645	template<typename KeyT>
646	APValue &createTemporary(const KeyT *Key, QualType T,
647	ScopeKind Scope, LValue &LV);
648
649	APValue &createConstexprUnknownAPValues(const VarDecl *Key,
650	APValue::LValueBase Base);
651
652	/// Allocate storage for a parameter of a function call made in this frame.
653	APValue &createParam(CallRef Args, const ParmVarDecl *PVD, LValue &LV);
654
655	void describe(llvm::raw_ostream &OS) const override;
656
657	Frame *getCaller() const override { return Caller; }
658	SourceRange getCallRange() const override { return CallRange; }
659	const FunctionDecl *getCallee() const override { return Callee; }
660
661	bool isStdFunction() const {
662	for (const DeclContext *DC = Callee; DC; DC = DC->getParent())
663	if (DC->isStdNamespace())
664	return true;
665	return false;
666	}
667
668	/// Whether we're in a context where [[msvc::constexpr]] evaluation is
669	/// permitted. See MSConstexprDocs for description of permitted contexts.
670	bool CanEvalMSConstexpr = false;
671
672	private:
673	APValue &createLocal(APValue::LValueBase Base, const void *Key, QualType T,
674	ScopeKind Scope);
675	};
676
677	/// Temporarily override 'this'.
678	class ThisOverrideRAII {
679	public:
680	ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
681	: Frame(Frame), OldThis(Frame.This) {
682	if (Enable)
683	Frame.This = NewThis;
684	}
685	~ThisOverrideRAII() {
686	Frame.This = OldThis;
687	}
688	private:
689	CallStackFrame &Frame;
690	const LValue *OldThis;
691	};
692
693	// A shorthand time trace scope struct, prints source range, for example
694	// {"name":"EvaluateAsRValue","args":{"detail":"<test.cc:8:21, col:25>"}}}
695	class ExprTimeTraceScope {
696	public:
697	ExprTimeTraceScope(const Expr *E, const ASTContext &Ctx, StringRef Name)
698	: TimeScope(Name, [E, &Ctx] {
699	return E->getSourceRange().printToString(Ctx.getSourceManager());
700	}) {}
701
702	private:
703	llvm::TimeTraceScope TimeScope;
704	};
705
706	/// RAII object used to change the current ability of
707	/// [[msvc::constexpr]] evaulation.
708	struct MSConstexprContextRAII {
709	CallStackFrame &Frame;
710	bool OldValue;
711	explicit MSConstexprContextRAII(CallStackFrame &Frame, bool Value)
712	: Frame(Frame), OldValue(Frame.CanEvalMSConstexpr) {
713	Frame.CanEvalMSConstexpr = Value;
714	}
715
716	~MSConstexprContextRAII() { Frame.CanEvalMSConstexpr = OldValue; }
717	};
718	}
719
720	static bool HandleDestruction(EvalInfo &Info, const Expr *E,
721	const LValue &This, QualType ThisType);
722	static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
723	APValue::LValueBase LVBase, APValue &Value,
724	QualType T);
725
726	namespace {
727	/// A cleanup, and a flag indicating whether it is lifetime-extended.
728	class Cleanup {
729	llvm::PointerIntPair<APValue*, 2, ScopeKind> Value;
730	APValue::LValueBase Base;
731	QualType T;
732
733	public:
734	Cleanup(APValue *Val, APValue::LValueBase Base, QualType T,
735	ScopeKind Scope)
736	: Value(Val, Scope), Base(Base), T(T) {}
737
738	/// Determine whether this cleanup should be performed at the end of the
739	/// given kind of scope.
740	bool isDestroyedAtEndOf(ScopeKind K) const {
741	return (int)Value.getInt() >= (int)K;
742	}
743	bool endLifetime(EvalInfo &Info, bool RunDestructors) {
744	if (RunDestructors) {
745	SourceLocation Loc;
746	if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
747	Loc = VD->getLocation();
748	else if (const Expr *E = Base.dyn_cast<const Expr*>())
749	Loc = E->getExprLoc();
750	return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T);
751	}
752	*Value.getPointer() = APValue();
753	return true;
754	}
755
756	bool hasSideEffect() {
757	return T.isDestructedType();
758	}
759	};
760
761	/// A reference to an object whose construction we are currently evaluating.
762	struct ObjectUnderConstruction {
763	APValue::LValueBase Base;
764	ArrayRef<APValue::LValuePathEntry> Path;
765	friend bool operator==(const ObjectUnderConstruction &LHS,
766	const ObjectUnderConstruction &RHS) {
767	return LHS.Base == RHS.Base && LHS.Path == RHS.Path;
768	}
769	friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) {
770	return llvm::hash_combine(args: Obj.Base, args: Obj.Path);
771	}
772	};
773	enum class ConstructionPhase {
774	None,
775	Bases,
776	AfterBases,
777	AfterFields,
778	Destroying,
779	DestroyingBases
780	};
781	}
782
783	namespace llvm {
784	template<> struct DenseMapInfo<ObjectUnderConstruction> {
785	using Base = DenseMapInfo<APValue::LValueBase>;
786	static ObjectUnderConstruction getEmptyKey() {
787	return {.Base: Base::getEmptyKey(), .Path: {}}; }
788	static ObjectUnderConstruction getTombstoneKey() {
789	return {.Base: Base::getTombstoneKey(), .Path: {}};
790	}
791	static unsigned getHashValue(const ObjectUnderConstruction &Object) {
792	return hash_value(Obj: Object);
793	}
794	static bool isEqual(const ObjectUnderConstruction &LHS,
795	const ObjectUnderConstruction &RHS) {
796	return LHS == RHS;
797	}
798	};
799	}
800
801	namespace {
802	/// A dynamically-allocated heap object.
803	struct DynAlloc {
804	/// The value of this heap-allocated object.
805	APValue Value;
806	/// The allocating expression; used for diagnostics. Either a CXXNewExpr
807	/// or a CallExpr (the latter is for direct calls to operator new inside
808	/// std::allocator<T>::allocate).
809	const Expr *AllocExpr = nullptr;
810
811	enum Kind {
812	New,
813	ArrayNew,
814	StdAllocator
815	};
816
817	/// Get the kind of the allocation. This must match between allocation
818	/// and deallocation.
819	Kind getKind() const {
820	if (auto *NE = dyn_cast<CXXNewExpr>(Val: AllocExpr))
821	return NE->isArray() ? ArrayNew : New;
822	assert(isa<CallExpr>(AllocExpr));
823	return StdAllocator;
824	}
825	};
826
827	struct DynAllocOrder {
828	bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const {
829	return L.getIndex() < R.getIndex();
830	}
831	};
832
833	/// EvalInfo - This is a private struct used by the evaluator to capture
834	/// information about a subexpression as it is folded. It retains information
835	/// about the AST context, but also maintains information about the folded
836	/// expression.
837	///
838	/// If an expression could be evaluated, it is still possible it is not a C
839	/// "integer constant expression" or constant expression. If not, this struct
840	/// captures information about how and why not.
841	///
842	/// One bit of information passed *into* the request for constant folding
843	/// indicates whether the subexpression is "evaluated" or not according to C
844	/// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
845	/// evaluate the expression regardless of what the RHS is, but C only allows
846	/// certain things in certain situations.
847	class EvalInfo : public interp::State {
848	public:
849	ASTContext &Ctx;
850
851	/// EvalStatus - Contains information about the evaluation.
852	Expr::EvalStatus &EvalStatus;
853
854	/// CurrentCall - The top of the constexpr call stack.
855	CallStackFrame *CurrentCall;
856
857	/// CallStackDepth - The number of calls in the call stack right now.
858	unsigned CallStackDepth;
859
860	/// NextCallIndex - The next call index to assign.
861	unsigned NextCallIndex;
862
863	/// StepsLeft - The remaining number of evaluation steps we're permitted
864	/// to perform. This is essentially a limit for the number of statements
865	/// we will evaluate.
866	unsigned StepsLeft;
867
868	/// Enable the experimental new constant interpreter. If an expression is
869	/// not supported by the interpreter, an error is triggered.
870	bool EnableNewConstInterp;
871
872	/// BottomFrame - The frame in which evaluation started. This must be
873	/// initialized after CurrentCall and CallStackDepth.
874	CallStackFrame BottomFrame;
875
876	/// A stack of values whose lifetimes end at the end of some surrounding
877	/// evaluation frame.
878	llvm::SmallVector<Cleanup, 16> CleanupStack;
879
880	/// EvaluatingDecl - This is the declaration whose initializer is being
881	/// evaluated, if any.
882	APValue::LValueBase EvaluatingDecl;
883
884	enum class EvaluatingDeclKind {
885	None,
886	/// We're evaluating the construction of EvaluatingDecl.
887	Ctor,
888	/// We're evaluating the destruction of EvaluatingDecl.
889	Dtor,
890	};
891	EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None;
892
893	/// EvaluatingDeclValue - This is the value being constructed for the
894	/// declaration whose initializer is being evaluated, if any.
895	APValue *EvaluatingDeclValue;
896
897	/// Set of objects that are currently being constructed.
898	llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase>
899	ObjectsUnderConstruction;
900
901	/// Current heap allocations, along with the location where each was
902	/// allocated. We use std::map here because we need stable addresses
903	/// for the stored APValues.
904	std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs;
905
906	/// The number of heap allocations performed so far in this evaluation.
907	unsigned NumHeapAllocs = 0;
908
909	struct EvaluatingConstructorRAII {
910	EvalInfo &EI;
911	ObjectUnderConstruction Object;
912	bool DidInsert;
913	EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object,
914	bool HasBases)
915	: EI(EI), Object(Object) {
916	DidInsert =
917	EI.ObjectsUnderConstruction
918	.insert(KV: {Object, HasBases ? ConstructionPhase::Bases
919	: ConstructionPhase::AfterBases})
920	.second;
921	}
922	void finishedConstructingBases() {
923	EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
924	}
925	void finishedConstructingFields() {
926	EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields;
927	}
928	~EvaluatingConstructorRAII() {
929	if (DidInsert) EI.ObjectsUnderConstruction.erase(Val: Object);
930	}
931	};
932
933	struct EvaluatingDestructorRAII {
934	EvalInfo &EI;
935	ObjectUnderConstruction Object;
936	bool DidInsert;
937	EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object)
938	: EI(EI), Object(Object) {
939	DidInsert = EI.ObjectsUnderConstruction
940	.insert(KV: {Object, ConstructionPhase::Destroying})
941	.second;
942	}
943	void startedDestroyingBases() {
944	EI.ObjectsUnderConstruction[Object] =
945	ConstructionPhase::DestroyingBases;
946	}
947	~EvaluatingDestructorRAII() {
948	if (DidInsert)
949	EI.ObjectsUnderConstruction.erase(Val: Object);
950	}
951	};
952
953	ConstructionPhase
954	isEvaluatingCtorDtor(APValue::LValueBase Base,
955	ArrayRef<APValue::LValuePathEntry> Path) {
956	return ObjectsUnderConstruction.lookup(Val: {.Base: Base, .Path: Path});
957	}
958
959	/// If we're currently speculatively evaluating, the outermost call stack
960	/// depth at which we can mutate state, otherwise 0.
961	unsigned SpeculativeEvaluationDepth = 0;
962
963	/// The current array initialization index, if we're performing array
964	/// initialization.
965	uint64_t ArrayInitIndex = -1;
966
967	/// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
968	/// notes attached to it will also be stored, otherwise they will not be.
969	bool HasActiveDiagnostic;
970
971	/// Have we emitted a diagnostic explaining why we couldn't constant
972	/// fold (not just why it's not strictly a constant expression)?
973	bool HasFoldFailureDiagnostic;
974
975	/// Whether we're checking that an expression is a potential constant
976	/// expression. If so, do not fail on constructs that could become constant
977	/// later on (such as a use of an undefined global).
978	bool CheckingPotentialConstantExpression = false;
979
980	/// Whether we're checking for an expression that has undefined behavior.
981	/// If so, we will produce warnings if we encounter an operation that is
982	/// always undefined.
983	///
984	/// Note that we still need to evaluate the expression normally when this
985	/// is set; this is used when evaluating ICEs in C.
986	bool CheckingForUndefinedBehavior = false;
987
988	enum EvaluationMode {
989	/// Evaluate as a constant expression. Stop if we find that the expression
990	/// is not a constant expression.
991	EM_ConstantExpression,
992
993	/// Evaluate as a constant expression. Stop if we find that the expression
994	/// is not a constant expression. Some expressions can be retried in the
995	/// optimizer if we don't constant fold them here, but in an unevaluated
996	/// context we try to fold them immediately since the optimizer never
997	/// gets a chance to look at it.
998	EM_ConstantExpressionUnevaluated,
999
1000	/// Fold the expression to a constant. Stop if we hit a side-effect that
1001	/// we can't model.
1002	EM_ConstantFold,
1003
1004	/// Evaluate in any way we know how. Don't worry about side-effects that
1005	/// can't be modeled.
1006	EM_IgnoreSideEffects,
1007	} EvalMode;
1008
1009	/// Are we checking whether the expression is a potential constant
1010	/// expression?
1011	bool checkingPotentialConstantExpression() const override {
1012	return CheckingPotentialConstantExpression;
1013	}
1014
1015	/// Are we checking an expression for overflow?
1016	// FIXME: We should check for any kind of undefined or suspicious behavior
1017	// in such constructs, not just overflow.
1018	bool checkingForUndefinedBehavior() const override {
1019	return CheckingForUndefinedBehavior;
1020	}
1021
1022	EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
1023	: Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
1024	CallStackDepth(0), NextCallIndex(1),
1025	StepsLeft(C.getLangOpts().ConstexprStepLimit),
1026	EnableNewConstInterp(C.getLangOpts().EnableNewConstInterp),
1027	BottomFrame(*this, SourceLocation(), /*Callee=*/nullptr,
1028	/*This=*/nullptr,
1029	/*CallExpr=*/nullptr, CallRef()),
1030	EvaluatingDecl((const ValueDecl *)nullptr),
1031	EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
1032	HasFoldFailureDiagnostic(false), EvalMode(Mode) {}
1033
1034	~EvalInfo() {
1035	discardCleanups();
1036	}
1037
1038	ASTContext &getASTContext() const override { return Ctx; }
1039
1040	void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
1041	EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {
1042	EvaluatingDecl = Base;
1043	IsEvaluatingDecl = EDK;
1044	EvaluatingDeclValue = &Value;
1045	}
1046
1047	bool CheckCallLimit(SourceLocation Loc) {
1048	// Don't perform any constexpr calls (other than the call we're checking)
1049	// when checking a potential constant expression.
1050	if (checkingPotentialConstantExpression() && CallStackDepth > 1)
1051	return false;
1052	if (NextCallIndex == 0) {
1053	// NextCallIndex has wrapped around.
1054	FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
1055	return false;
1056	}
1057	if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
1058	return true;
1059	FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
1060	<< getLangOpts().ConstexprCallDepth;
1061	return false;
1062	}
1063
1064	bool CheckArraySize(SourceLocation Loc, unsigned BitWidth,
1065	uint64_t ElemCount, bool Diag) {
1066	// FIXME: GH63562
1067	// APValue stores array extents as unsigned,
1068	// so anything that is greater that unsigned would overflow when
1069	// constructing the array, we catch this here.
1070	if (BitWidth > ConstantArrayType::getMaxSizeBits(Context: Ctx) ||
1071	ElemCount > uint64_t(std::numeric_limits<unsigned>::max())) {
1072	if (Diag)
1073	FFDiag(Loc, diag::note_constexpr_new_too_large) << ElemCount;
1074	return false;
1075	}
1076
1077	// FIXME: GH63562
1078	// Arrays allocate an APValue per element.
1079	// We use the number of constexpr steps as a proxy for the maximum size
1080	// of arrays to avoid exhausting the system resources, as initialization
1081	// of each element is likely to take some number of steps anyway.
1082	uint64_t Limit = Ctx.getLangOpts().ConstexprStepLimit;
1083	if (ElemCount > Limit) {
1084	if (Diag)
1085	FFDiag(Loc, diag::note_constexpr_new_exceeds_limits)
1086	<< ElemCount << Limit;
1087	return false;
1088	}
1089	return true;
1090	}
1091
1092	std::pair<CallStackFrame *, unsigned>
1093	getCallFrameAndDepth(unsigned CallIndex) {
1094	assert(CallIndex && "no call index in getCallFrameAndDepth");
1095	// We will eventually hit BottomFrame, which has Index 1, so Frame can't
1096	// be null in this loop.
1097	unsigned Depth = CallStackDepth;
1098	CallStackFrame *Frame = CurrentCall;
1099	while (Frame->Index > CallIndex) {
1100	Frame = Frame->Caller;
1101	--Depth;
1102	}
1103	if (Frame->Index == CallIndex)
1104	return {Frame, Depth};
1105	return {nullptr, 0};
1106	}
1107
1108	bool nextStep(const Stmt *S) {
1109	if (!StepsLeft) {
1110	FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
1111	return false;
1112	}
1113	--StepsLeft;
1114	return true;
1115	}
1116
1117	APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV);
1118
1119	std::optional<DynAlloc *> lookupDynamicAlloc(DynamicAllocLValue DA) {
1120	std::optional<DynAlloc *> Result;
1121	auto It = HeapAllocs.find(x: DA);
1122	if (It != HeapAllocs.end())
1123	Result = &It->second;
1124	return Result;
1125	}
1126
1127	/// Get the allocated storage for the given parameter of the given call.
1128	APValue *getParamSlot(CallRef Call, const ParmVarDecl *PVD) {
1129	CallStackFrame *Frame = getCallFrameAndDepth(CallIndex: Call.CallIndex).first;
1130	return Frame ? Frame->getTemporary(Key: Call.getOrigParam(PVD), Version: Call.Version)
1131	: nullptr;
1132	}
1133
1134	/// Information about a stack frame for std::allocator<T>::[de]allocate.
1135	struct StdAllocatorCaller {
1136	unsigned FrameIndex;
1137	QualType ElemType;
1138	const Expr *Call;
1139	explicit operator bool() const { return FrameIndex != 0; };
1140	};
1141
1142	StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const {
1143	for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame;
1144	Call = Call->Caller) {
1145	const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Val: Call->Callee);
1146	if (!MD)
1147	continue;
1148	const IdentifierInfo *FnII = MD->getIdentifier();
1149	if (!FnII || !FnII->isStr(Str: FnName))
1150	continue;
1151
1152	const auto *CTSD =
1153	dyn_cast<ClassTemplateSpecializationDecl>(Val: MD->getParent());
1154	if (!CTSD)
1155	continue;
1156
1157	const IdentifierInfo *ClassII = CTSD->getIdentifier();
1158	const TemplateArgumentList &TAL = CTSD->getTemplateArgs();
1159	if (CTSD->isInStdNamespace() && ClassII &&
1160	ClassII->isStr(Str: "allocator") && TAL.size() >= 1 &&
1161	TAL[0].getKind() == TemplateArgument::Type)
1162	return {Call->Index, TAL[0].getAsType(), Call->CallExpr};
1163	}
1164
1165	return {};
1166	}
1167
1168	void performLifetimeExtension() {
1169	// Disable the cleanups for lifetime-extended temporaries.
1170	llvm::erase_if(C&: CleanupStack, P: [](Cleanup &C) {
1171	return !C.isDestroyedAtEndOf(K: ScopeKind::FullExpression);
1172	});
1173	}
1174
1175	/// Throw away any remaining cleanups at the end of evaluation. If any
1176	/// cleanups would have had a side-effect, note that as an unmodeled
1177	/// side-effect and return false. Otherwise, return true.
1178	bool discardCleanups() {
1179	for (Cleanup &C : CleanupStack) {
1180	if (C.hasSideEffect() && !noteSideEffect()) {
1181	CleanupStack.clear();
1182	return false;
1183	}
1184	}
1185	CleanupStack.clear();
1186	return true;
1187	}
1188
1189	private:
1190	interp::Frame *getCurrentFrame() override { return CurrentCall; }
1191	const interp::Frame *getBottomFrame() const override { return &BottomFrame; }
1192
1193	bool hasActiveDiagnostic() override { return HasActiveDiagnostic; }
1194	void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; }
1195
1196	void setFoldFailureDiagnostic(bool Flag) override {
1197	HasFoldFailureDiagnostic = Flag;
1198	}
1199
1200	Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; }
1201
1202	// If we have a prior diagnostic, it will be noting that the expression
1203	// isn't a constant expression. This diagnostic is more important,
1204	// unless we require this evaluation to produce a constant expression.
1205	//
1206	// FIXME: We might want to show both diagnostics to the user in
1207	// EM_ConstantFold mode.
1208	bool hasPriorDiagnostic() override {
1209	if (!EvalStatus.Diag->empty()) {
1210	switch (EvalMode) {
1211	case EM_ConstantFold:
1212	case EM_IgnoreSideEffects:
1213	if (!HasFoldFailureDiagnostic)
1214	break;
1215	// We've already failed to fold something. Keep that diagnostic.
1216	[[fallthrough]];
1217	case EM_ConstantExpression:
1218	case EM_ConstantExpressionUnevaluated:
1219	setActiveDiagnostic(false);
1220	return true;
1221	}
1222	}
1223	return false;
1224	}
1225
1226	unsigned getCallStackDepth() override { return CallStackDepth; }
1227
1228	public:
1229	/// Should we continue evaluation after encountering a side-effect that we
1230	/// couldn't model?
1231	bool keepEvaluatingAfterSideEffect() const override {
1232	switch (EvalMode) {
1233	case EM_IgnoreSideEffects:
1234	return true;
1235
1236	case EM_ConstantExpression:
1237	case EM_ConstantExpressionUnevaluated:
1238	case EM_ConstantFold:
1239	// By default, assume any side effect might be valid in some other
1240	// evaluation of this expression from a different context.
1241	return checkingPotentialConstantExpression() ||
1242	checkingForUndefinedBehavior();
1243	}
1244	llvm_unreachable("Missed EvalMode case");
1245	}
1246
1247	/// Note that we have had a side-effect, and determine whether we should
1248	/// keep evaluating.
1249	bool noteSideEffect() override {
1250	EvalStatus.HasSideEffects = true;
1251	return keepEvaluatingAfterSideEffect();
1252	}
1253
1254	/// Should we continue evaluation after encountering undefined behavior?
1255	bool keepEvaluatingAfterUndefinedBehavior() {
1256	switch (EvalMode) {
1257	case EM_IgnoreSideEffects:
1258	case EM_ConstantFold:
1259	return true;
1260
1261	case EM_ConstantExpression:
1262	case EM_ConstantExpressionUnevaluated:
1263	return checkingForUndefinedBehavior();
1264	}
1265	llvm_unreachable("Missed EvalMode case");
1266	}
1267
1268	/// Note that we hit something that was technically undefined behavior, but
1269	/// that we can evaluate past it (such as signed overflow or floating-point
1270	/// division by zero.)
1271	bool noteUndefinedBehavior() override {
1272	EvalStatus.HasUndefinedBehavior = true;
1273	return keepEvaluatingAfterUndefinedBehavior();
1274	}
1275
1276	/// Should we continue evaluation as much as possible after encountering a
1277	/// construct which can't be reduced to a value?
1278	bool keepEvaluatingAfterFailure() const override {
1279	if (!StepsLeft)
1280	return false;
1281
1282	switch (EvalMode) {
1283	case EM_ConstantExpression:
1284	case EM_ConstantExpressionUnevaluated:
1285	case EM_ConstantFold:
1286	case EM_IgnoreSideEffects:
1287	return checkingPotentialConstantExpression() ||
1288	checkingForUndefinedBehavior();
1289	}
1290	llvm_unreachable("Missed EvalMode case");
1291	}
1292
1293	/// Notes that we failed to evaluate an expression that other expressions
1294	/// directly depend on, and determine if we should keep evaluating. This
1295	/// should only be called if we actually intend to keep evaluating.
1296	///
1297	/// Call noteSideEffect() instead if we may be able to ignore the value that
1298	/// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
1299	///
1300	/// (Foo(), 1) // use noteSideEffect
1301	/// (Foo() || true) // use noteSideEffect
1302	/// Foo() + 1 // use noteFailure
1303	[[nodiscard]] bool noteFailure() {
1304	// Failure when evaluating some expression often means there is some
1305	// subexpression whose evaluation was skipped. Therefore, (because we
1306	// don't track whether we skipped an expression when unwinding after an
1307	// evaluation failure) every evaluation failure that bubbles up from a
1308	// subexpression implies that a side-effect has potentially happened. We
1309	// skip setting the HasSideEffects flag to true until we decide to
1310	// continue evaluating after that point, which happens here.
1311	bool KeepGoing = keepEvaluatingAfterFailure();
1312	EvalStatus.HasSideEffects |= KeepGoing;
1313	return KeepGoing;
1314	}
1315
1316	class ArrayInitLoopIndex {
1317	EvalInfo &Info;
1318	uint64_t OuterIndex;
1319
1320	public:
1321	ArrayInitLoopIndex(EvalInfo &Info)
1322	: Info(Info), OuterIndex(Info.ArrayInitIndex) {
1323	Info.ArrayInitIndex = 0;
1324	}
1325	~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
1326
1327	operator uint64_t&() { return Info.ArrayInitIndex; }
1328	};
1329	};
1330
1331	/// Object used to treat all foldable expressions as constant expressions.
1332	struct FoldConstant {
1333	EvalInfo &Info;
1334	bool Enabled;
1335	bool HadNoPriorDiags;
1336	EvalInfo::EvaluationMode OldMode;
1337
1338	explicit FoldConstant(EvalInfo &Info, bool Enabled)
1339	: Info(Info),
1340	Enabled(Enabled),
1341	HadNoPriorDiags(Info.EvalStatus.Diag &&
1342	Info.EvalStatus.Diag->empty() &&
1343	!Info.EvalStatus.HasSideEffects),
1344	OldMode(Info.EvalMode) {
1345	if (Enabled)
1346	Info.EvalMode = EvalInfo::EM_ConstantFold;
1347	}
1348	void keepDiagnostics() { Enabled = false; }
1349	~FoldConstant() {
1350	if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
1351	!Info.EvalStatus.HasSideEffects)
1352	Info.EvalStatus.Diag->clear();
1353	Info.EvalMode = OldMode;
1354	}
1355	};
1356
1357	/// RAII object used to set the current evaluation mode to ignore
1358	/// side-effects.
1359	struct IgnoreSideEffectsRAII {
1360	EvalInfo &Info;
1361	EvalInfo::EvaluationMode OldMode;
1362	explicit IgnoreSideEffectsRAII(EvalInfo &Info)
1363	: Info(Info), OldMode(Info.EvalMode) {
1364	Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
1365	}
1366
1367	~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
1368	};
1369
1370	/// RAII object used to optionally suppress diagnostics and side-effects from
1371	/// a speculative evaluation.
1372	class SpeculativeEvaluationRAII {
1373	EvalInfo *Info = nullptr;
1374	Expr::EvalStatus OldStatus;
1375	unsigned OldSpeculativeEvaluationDepth = 0;
1376
1377	void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
1378	Info = Other.Info;
1379	OldStatus = Other.OldStatus;
1380	OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth;
1381	Other.Info = nullptr;
1382	}
1383
1384	void maybeRestoreState() {
1385	if (!Info)
1386	return;
1387
1388	Info->EvalStatus = OldStatus;
1389	Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth;
1390	}
1391
1392	public:
1393	SpeculativeEvaluationRAII() = default;
1394
1395	SpeculativeEvaluationRAII(
1396	EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
1397	: Info(&Info), OldStatus(Info.EvalStatus),
1398	OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) {
1399	Info.EvalStatus.Diag = NewDiag;
1400	Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1;
1401	}
1402
1403	SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
1404	SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
1405	moveFromAndCancel(Other: std::move(Other));
1406	}
1407
1408	SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
1409	maybeRestoreState();
1410	moveFromAndCancel(Other: std::move(Other));
1411	return *this;
1412	}
1413
1414	~SpeculativeEvaluationRAII() { maybeRestoreState(); }
1415	};
1416
1417	/// RAII object wrapping a full-expression or block scope, and handling
1418	/// the ending of the lifetime of temporaries created within it.
1419	template<ScopeKind Kind>
1420	class ScopeRAII {
1421	EvalInfo &Info;
1422	unsigned OldStackSize;
1423	public:
1424	ScopeRAII(EvalInfo &Info)
1425	: Info(Info), OldStackSize(Info.CleanupStack.size()) {
1426	// Push a new temporary version. This is needed to distinguish between
1427	// temporaries created in different iterations of a loop.
1428	Info.CurrentCall->pushTempVersion();
1429	}
1430	bool destroy(bool RunDestructors = true) {
1431	bool OK = cleanup(Info, RunDestructors, OldStackSize);
1432	OldStackSize = -1U;
1433	return OK;
1434	}
1435	~ScopeRAII() {
1436	if (OldStackSize != -1U)
1437	destroy(RunDestructors: false);
1438	// Body moved to a static method to encourage the compiler to inline away
1439	// instances of this class.
1440	Info.CurrentCall->popTempVersion();
1441	}
1442	private:
1443	static bool cleanup(EvalInfo &Info, bool RunDestructors,
1444	unsigned OldStackSize) {
1445	assert(OldStackSize <= Info.CleanupStack.size() &&
1446	"running cleanups out of order?");
1447
1448	// Run all cleanups for a block scope, and non-lifetime-extended cleanups
1449	// for a full-expression scope.
1450	bool Success = true;
1451	for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I) {
1452	if (Info.CleanupStack[I - 1].isDestroyedAtEndOf(K: Kind)) {
1453	if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) {
1454	Success = false;
1455	break;
1456	}
1457	}
1458	}
1459
1460	// Compact any retained cleanups.
1461	auto NewEnd = Info.CleanupStack.begin() + OldStackSize;
1462	if (Kind != ScopeKind::Block)
1463	NewEnd =
1464	std::remove_if(NewEnd, Info.CleanupStack.end(), [](Cleanup &C) {
1465	return C.isDestroyedAtEndOf(K: Kind);
1466	});
1467	Info.CleanupStack.erase(CS: NewEnd, CE: Info.CleanupStack.end());
1468	return Success;
1469	}
1470	};
1471	typedef ScopeRAII<ScopeKind::Block> BlockScopeRAII;
1472	typedef ScopeRAII<ScopeKind::FullExpression> FullExpressionRAII;
1473	typedef ScopeRAII<ScopeKind::Call> CallScopeRAII;
1474	}
1475
1476	bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
1477	CheckSubobjectKind CSK) {
1478	if (Invalid)
1479	return false;
1480	if (isOnePastTheEnd()) {
1481	Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
1482	<< CSK;
1483	setInvalid();
1484	return false;
1485	}
1486	// Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
1487	// must actually be at least one array element; even a VLA cannot have a
1488	// bound of zero. And if our index is nonzero, we already had a CCEDiag.
1489	return true;
1490	}
1491
1492	void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
1493	const Expr *E) {
1494	Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
1495	// Do not set the designator as invalid: we can represent this situation,
1496	// and correct handling of __builtin_object_size requires us to do so.
1497	}
1498
1499	void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
1500	const Expr *E,
1501	const APSInt &N) {
1502	// If we're complaining, we must be able to statically determine the size of
1503	// the most derived array.
1504	if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
1505	Info.CCEDiag(E, diag::note_constexpr_array_index)
1506	<< N << /*array*/ 0
1507	<< static_cast<unsigned>(getMostDerivedArraySize());
1508	else
1509	Info.CCEDiag(E, diag::note_constexpr_array_index)
1510	<< N << /*non-array*/ 1;
1511	setInvalid();
1512	}
1513
1514	CallStackFrame::CallStackFrame(EvalInfo &Info, SourceRange CallRange,
1515	const FunctionDecl *Callee, const LValue *This,
1516	const Expr *CallExpr, CallRef Call)
1517	: Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
1518	CallExpr(CallExpr), Arguments(Call), CallRange(CallRange),
1519	Index(Info.NextCallIndex++) {
1520	Info.CurrentCall = this;
1521	++Info.CallStackDepth;
1522	}
1523
1524	CallStackFrame::~CallStackFrame() {
1525	assert(Info.CurrentCall == this && "calls retired out of order");
1526	--Info.CallStackDepth;
1527	Info.CurrentCall = Caller;
1528	}
1529
1530	static bool isRead(AccessKinds AK) {
1531	return AK == AK_Read || AK == AK_ReadObjectRepresentation ||
1532	AK == AK_IsWithinLifetime;
1533	}
1534
1535	static bool isModification(AccessKinds AK) {
1536	switch (AK) {
1537	case AK_Read:
1538	case AK_ReadObjectRepresentation:
1539	case AK_MemberCall:
1540	case AK_DynamicCast:
1541	case AK_TypeId:
1542	case AK_IsWithinLifetime:
1543	return false;
1544	case AK_Assign:
1545	case AK_Increment:
1546	case AK_Decrement:
1547	case AK_Construct:
1548	case AK_Destroy:
1549	return true;
1550	}
1551	llvm_unreachable("unknown access kind");
1552	}
1553
1554	static bool isAnyAccess(AccessKinds AK) {
1555	return isRead(AK) || isModification(AK);
1556	}
1557
1558	/// Is this an access per the C++ definition?
1559	static bool isFormalAccess(AccessKinds AK) {
1560	return isAnyAccess(AK) && AK != AK_Construct && AK != AK_Destroy &&
1561	AK != AK_IsWithinLifetime;
1562	}
1563
1564	/// Is this kind of axcess valid on an indeterminate object value?
1565	static bool isValidIndeterminateAccess(AccessKinds AK) {
1566	switch (AK) {
1567	case AK_Read:
1568	case AK_Increment:
1569	case AK_Decrement:
1570	// These need the object's value.
1571	return false;
1572
1573	case AK_IsWithinLifetime:
1574	case AK_ReadObjectRepresentation:
1575	case AK_Assign:
1576	case AK_Construct:
1577	case AK_Destroy:
1578	// Construction and destruction don't need the value.
1579	return true;
1580
1581	case AK_MemberCall:
1582	case AK_DynamicCast:
1583	case AK_TypeId:
1584	// These aren't really meaningful on scalars.
1585	return true;
1586	}
1587	llvm_unreachable("unknown access kind");
1588	}
1589
1590	namespace {
1591	struct ComplexValue {
1592	private:
1593	bool IsInt;
1594
1595	public:
1596	APSInt IntReal, IntImag;
1597	APFloat FloatReal, FloatImag;
1598
1599	ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
1600
1601	void makeComplexFloat() { IsInt = false; }
1602	bool isComplexFloat() const { return !IsInt; }
1603	APFloat &getComplexFloatReal() { return FloatReal; }
1604	APFloat &getComplexFloatImag() { return FloatImag; }
1605
1606	void makeComplexInt() { IsInt = true; }
1607	bool isComplexInt() const { return IsInt; }
1608	APSInt &getComplexIntReal() { return IntReal; }
1609	APSInt &getComplexIntImag() { return IntImag; }
1610
1611	void moveInto(APValue &v) const {
1612	if (isComplexFloat())
1613	v = APValue(FloatReal, FloatImag);
1614	else
1615	v = APValue(IntReal, IntImag);
1616	}
1617	void setFrom(const APValue &v) {
1618	assert(v.isComplexFloat() || v.isComplexInt());
1619	if (v.isComplexFloat()) {
1620	makeComplexFloat();
1621	FloatReal = v.getComplexFloatReal();
1622	FloatImag = v.getComplexFloatImag();
1623	} else {
1624	makeComplexInt();
1625	IntReal = v.getComplexIntReal();
1626	IntImag = v.getComplexIntImag();
1627	}
1628	}
1629	};
1630
1631	struct LValue {
1632	APValue::LValueBase Base;
1633	CharUnits Offset;
1634	SubobjectDesignator Designator;
1635	bool IsNullPtr : 1;
1636	bool InvalidBase : 1;
1637	// P2280R4 track if we have an unknown reference or pointer.
1638	bool AllowConstexprUnknown = false;
1639
1640	const APValue::LValueBase getLValueBase() const { return Base; }
1641	bool allowConstexprUnknown() const { return AllowConstexprUnknown; }
1642	CharUnits &getLValueOffset() { return Offset; }
1643	const CharUnits &getLValueOffset() const { return Offset; }
1644	SubobjectDesignator &getLValueDesignator() { return Designator; }
1645	const SubobjectDesignator &getLValueDesignator() const { return Designator;}
1646	bool isNullPointer() const { return IsNullPtr;}
1647
1648	unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
1649	unsigned getLValueVersion() const { return Base.getVersion(); }
1650
1651	void moveInto(APValue &V) const {
1652	if (Designator.Invalid)
1653	V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
1654	else {
1655	assert(!InvalidBase && "APValues can't handle invalid LValue bases");
1656	V = APValue(Base, Offset, Designator.Entries,
1657	Designator.IsOnePastTheEnd, IsNullPtr);
1658	}
1659	if (AllowConstexprUnknown)
1660	V.setConstexprUnknown();
1661	}
1662	void setFrom(ASTContext &Ctx, const APValue &V) {
1663	assert(V.isLValue() && "Setting LValue from a non-LValue?");
1664	Base = V.getLValueBase();
1665	Offset = V.getLValueOffset();
1666	InvalidBase = false;
1667	Designator = SubobjectDesignator(Ctx, V);
1668	IsNullPtr = V.isNullPointer();
1669	AllowConstexprUnknown = V.allowConstexprUnknown();
1670	}
1671
1672	void set(APValue::LValueBase B, bool BInvalid = false) {
1673	#ifndef NDEBUG
1674	// We only allow a few types of invalid bases. Enforce that here.
1675	if (BInvalid) {
1676	const auto *E = B.get<const Expr *>();
1677	assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
1678	"Unexpected type of invalid base");
1679	}
1680	#endif
1681
1682	Base = B;
1683	Offset = CharUnits::fromQuantity(Quantity: 0);
1684	InvalidBase = BInvalid;
1685	Designator = SubobjectDesignator(getType(B));
1686	IsNullPtr = false;
1687	AllowConstexprUnknown = false;
1688	}
1689
1690	void setNull(ASTContext &Ctx, QualType PointerTy) {
1691	Base = (const ValueDecl *)nullptr;
1692	Offset =
1693	CharUnits::fromQuantity(Quantity: Ctx.getTargetNullPointerValue(QT: PointerTy));
1694	InvalidBase = false;
1695	Designator = SubobjectDesignator(PointerTy->getPointeeType());
1696	IsNullPtr = true;
1697	AllowConstexprUnknown = false;
1698	}
1699
1700	void setInvalid(APValue::LValueBase B, unsigned I = 0) {
1701	set(B, BInvalid: true);
1702	}
1703
1704	std::string toString(ASTContext &Ctx, QualType T) const {
1705	APValue Printable;
1706	moveInto(V&: Printable);
1707	return Printable.getAsString(Ctx, Ty: T);
1708	}
1709
1710	private:
1711	// Check that this LValue is not based on a null pointer. If it is, produce
1712	// a diagnostic and mark the designator as invalid.
1713	template <typename GenDiagType>
1714	bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
1715	if (Designator.Invalid)
1716	return false;
1717	if (IsNullPtr) {
1718	GenDiag();
1719	Designator.setInvalid();
1720	return false;
1721	}
1722	return true;
1723	}
1724
1725	public:
1726	bool checkNullPointer(EvalInfo &Info, const Expr *E,
1727	CheckSubobjectKind CSK) {
1728	return checkNullPointerDiagnosingWith(GenDiag: [&Info, E, CSK] {
1729	Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
1730	});
1731	}
1732
1733	bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
1734	AccessKinds AK) {
1735	return checkNullPointerDiagnosingWith(GenDiag: [&Info, E, AK] {
1736	Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
1737	});
1738	}
1739
1740	// Check this LValue refers to an object. If not, set the designator to be
1741	// invalid and emit a diagnostic.
1742	bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
1743	return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
1744	Designator.checkSubobject(Info, E, CSK);
1745	}
1746
1747	void addDecl(EvalInfo &Info, const Expr *E,
1748	const Decl *D, bool Virtual = false) {
1749	if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
1750	Designator.addDeclUnchecked(D, Virtual);
1751	}
1752	void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
1753	if (!Designator.Entries.empty()) {
1754	Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
1755	Designator.setInvalid();
1756	return;
1757	}
1758	if (checkSubobject(Info, E, CSK: CSK_ArrayToPointer)) {
1759	assert(getType(Base)->isPointerType() || getType(Base)->isArrayType());
1760	Designator.FirstEntryIsAnUnsizedArray = true;
1761	Designator.addUnsizedArrayUnchecked(ElemTy);
1762	}
1763	}
1764	void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
1765	if (checkSubobject(Info, E, CSK_ArrayToPointer))
1766	Designator.addArrayUnchecked(CAT);
1767	}
1768	void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
1769	if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
1770	Designator.addComplexUnchecked(EltTy, Imag);
1771	}
1772	void addVectorElement(EvalInfo &Info, const Expr *E, QualType EltTy,
1773	uint64_t Size, uint64_t Idx) {
1774	if (checkSubobject(Info, E, CSK_VectorElement))
1775	Designator.addVectorElementUnchecked(EltTy, Size, Idx);
1776	}
1777	void clearIsNullPointer() {
1778	IsNullPtr = false;
1779	}
1780	void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
1781	const APSInt &Index, CharUnits ElementSize) {
1782	// An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
1783	// but we're not required to diagnose it and it's valid in C++.)
1784	if (!Index)
1785	return;
1786
1787	// Compute the new offset in the appropriate width, wrapping at 64 bits.
1788	// FIXME: When compiling for a 32-bit target, we should use 32-bit
1789	// offsets.
1790	uint64_t Offset64 = Offset.getQuantity();
1791	uint64_t ElemSize64 = ElementSize.getQuantity();
1792	uint64_t Index64 = Index.extOrTrunc(width: 64).getZExtValue();
1793	Offset = CharUnits::fromQuantity(Quantity: Offset64 + ElemSize64 * Index64);
1794
1795	if (checkNullPointer(Info, E, CSK_ArrayIndex))
1796	Designator.adjustIndex(Info, E, Index);
1797	clearIsNullPointer();
1798	}
1799	void adjustOffset(CharUnits N) {
1800	Offset += N;
1801	if (N.getQuantity())
1802	clearIsNullPointer();
1803	}
1804	};
1805
1806	struct MemberPtr {
1807	MemberPtr() {}
1808	explicit MemberPtr(const ValueDecl *Decl)
1809	: DeclAndIsDerivedMember(Decl, false) {}
1810
1811	/// The member or (direct or indirect) field referred to by this member
1812	/// pointer, or 0 if this is a null member pointer.
1813	const ValueDecl *getDecl() const {
1814	return DeclAndIsDerivedMember.getPointer();
1815	}
1816	/// Is this actually a member of some type derived from the relevant class?
1817	bool isDerivedMember() const {
1818	return DeclAndIsDerivedMember.getInt();
1819	}
1820	/// Get the class which the declaration actually lives in.
1821	const CXXRecordDecl *getContainingRecord() const {
1822	return cast<CXXRecordDecl>(
1823	DeclAndIsDerivedMember.getPointer()->getDeclContext());
1824	}
1825
1826	void moveInto(APValue &V) const {
1827	V = APValue(getDecl(), isDerivedMember(), Path);
1828	}
1829	void setFrom(const APValue &V) {
1830	assert(V.isMemberPointer());
1831	DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
1832	DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
1833	Path.clear();
1834	llvm::append_range(C&: Path, R: V.getMemberPointerPath());
1835	}
1836
1837	/// DeclAndIsDerivedMember - The member declaration, and a flag indicating
1838	/// whether the member is a member of some class derived from the class type
1839	/// of the member pointer.
1840	llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
1841	/// Path - The path of base/derived classes from the member declaration's
1842	/// class (exclusive) to the class type of the member pointer (inclusive).
1843	SmallVector<const CXXRecordDecl*, 4> Path;
1844
1845	/// Perform a cast towards the class of the Decl (either up or down the
1846	/// hierarchy).
1847	bool castBack(const CXXRecordDecl *Class) {
1848	assert(!Path.empty());
1849	const CXXRecordDecl *Expected;
1850	if (Path.size() >= 2)
1851	Expected = Path[Path.size() - 2];
1852	else
1853	Expected = getContainingRecord();
1854	if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
1855	// C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
1856	// if B does not contain the original member and is not a base or
1857	// derived class of the class containing the original member, the result
1858	// of the cast is undefined.
1859	// C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
1860	// (D::*). We consider that to be a language defect.
1861	return false;
1862	}
1863	Path.pop_back();
1864	return true;
1865	}
1866	/// Perform a base-to-derived member pointer cast.
1867	bool castToDerived(const CXXRecordDecl *Derived) {
1868	if (!getDecl())
1869	return true;
1870	if (!isDerivedMember()) {
1871	Path.push_back(Elt: Derived);
1872	return true;
1873	}
1874	if (!castBack(Class: Derived))
1875	return false;
1876	if (Path.empty())
1877	DeclAndIsDerivedMember.setInt(false);
1878	return true;
1879	}
1880	/// Perform a derived-to-base member pointer cast.
1881	bool castToBase(const CXXRecordDecl *Base) {
1882	if (!getDecl())
1883	return true;
1884	if (Path.empty())
1885	DeclAndIsDerivedMember.setInt(true);
1886	if (isDerivedMember()) {
1887	Path.push_back(Elt: Base);
1888	return true;
1889	}
1890	return castBack(Class: Base);
1891	}
1892	};
1893
1894	/// Compare two member pointers, which are assumed to be of the same type.
1895	static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
1896	if (!LHS.getDecl() || !RHS.getDecl())
1897	return !LHS.getDecl() && !RHS.getDecl();
1898	if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
1899	return false;
1900	return LHS.Path == RHS.Path;
1901	}
1902	}
1903
1904	static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
1905	static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
1906	const LValue &This, const Expr *E,
1907	bool AllowNonLiteralTypes = false);
1908	static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
1909	bool InvalidBaseOK = false);
1910	static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
1911	bool InvalidBaseOK = false);
1912	static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
1913	EvalInfo &Info);
1914	static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
1915	static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
1916	static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
1917	EvalInfo &Info);
1918	static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
1919	static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
1920	static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
1921	EvalInfo &Info);
1922	static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
1923	static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
1924	EvalInfo &Info,
1925	std::string *StringResult = nullptr);
1926
1927	/// Evaluate an integer or fixed point expression into an APResult.
1928	static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
1929	EvalInfo &Info);
1930
1931	/// Evaluate only a fixed point expression into an APResult.
1932	static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
1933	EvalInfo &Info);
1934
1935	//===----------------------------------------------------------------------===//
1936	// Misc utilities
1937	//===----------------------------------------------------------------------===//
1938
1939	/// Negate an APSInt in place, converting it to a signed form if necessary, and
1940	/// preserving its value (by extending by up to one bit as needed).
1941	static void negateAsSigned(APSInt &Int) {
1942	if (Int.isUnsigned() || Int.isMinSignedValue()) {
1943	Int = Int.extend(width: Int.getBitWidth() + 1);
1944	Int.setIsSigned(true);
1945	}
1946	Int = -Int;
1947	}
1948
1949	template<typename KeyT>
1950	APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T,
1951	ScopeKind Scope, LValue &LV) {
1952	unsigned Version = getTempVersion();
1953	APValue::LValueBase Base(Key, Index, Version);
1954	LV.set(B: Base);
1955	return createLocal(Base, Key, T, Scope);
1956	}
1957
1958	APValue &
1959	CallStackFrame::createConstexprUnknownAPValues(const VarDecl *Key,
1960	APValue::LValueBase Base) {
1961	APValue &Result = ConstexprUnknownAPValues[MapKeyTy(Key, Base.getVersion())];
1962	Result = APValue(Base, CharUnits::Zero(), APValue::ConstexprUnknown{});
1963
1964	return Result;
1965	}
1966
1967	/// Allocate storage for a parameter of a function call made in this frame.
1968	APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD,
1969	LValue &LV) {
1970	assert(Args.CallIndex == Index && "creating parameter in wrong frame");
1971	APValue::LValueBase Base(PVD, Index, Args.Version);
1972	LV.set(B: Base);
1973	// We always destroy parameters at the end of the call, even if we'd allow
1974	// them to live to the end of the full-expression at runtime, in order to
1975	// give portable results and match other compilers.
1976	return createLocal(Base, Key: PVD, T: PVD->getType(), Scope: ScopeKind::Call);
1977	}
1978
1979	APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key,
1980	QualType T, ScopeKind Scope) {
1981	assert(Base.getCallIndex() == Index && "lvalue for wrong frame");
1982	unsigned Version = Base.getVersion();
1983	APValue &Result = Temporaries[MapKeyTy(Key, Version)];
1984	assert(Result.isAbsent() && "local created multiple times");
1985
1986	// If we're creating a local immediately in the operand of a speculative
1987	// evaluation, don't register a cleanup to be run outside the speculative
1988	// evaluation context, since we won't actually be able to initialize this
1989	// object.
1990	if (Index <= Info.SpeculativeEvaluationDepth) {
1991	if (T.isDestructedType())
1992	Info.noteSideEffect();
1993	} else {
1994	Info.CleanupStack.push_back(Elt: Cleanup(&Result, Base, T, Scope));
1995	}
1996	return Result;
1997	}
1998
1999	APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) {
2000	if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) {
2001	FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded);
2002	return nullptr;
2003	}
2004
2005	DynamicAllocLValue DA(NumHeapAllocs++);
2006	LV.set(B: APValue::LValueBase::getDynamicAlloc(LV: DA, Type: T));
2007	auto Result = HeapAllocs.emplace(args: std::piecewise_construct,
2008	args: std::forward_as_tuple(args&: DA), args: std::tuple<>());
2009	assert(Result.second && "reused a heap alloc index?");
2010	Result.first->second.AllocExpr = E;
2011	return &Result.first->second.Value;
2012	}
2013
2014	/// Produce a string describing the given constexpr call.
2015	void CallStackFrame::describe(raw_ostream &Out) const {
2016	unsigned ArgIndex = 0;
2017	bool IsMemberCall =
2018	isa<CXXMethodDecl>(Val: Callee) && !isa<CXXConstructorDecl>(Val: Callee) &&
2019	cast<CXXMethodDecl>(Val: Callee)->isImplicitObjectMemberFunction();
2020
2021	if (!IsMemberCall)
2022	Callee->getNameForDiagnostic(OS&: Out, Policy: Info.Ctx.getPrintingPolicy(),
2023	/*Qualified=*/false);
2024
2025	if (This && IsMemberCall) {
2026	if (const auto *MCE = dyn_cast_if_present<CXXMemberCallExpr>(Val: CallExpr)) {
2027	const Expr *Object = MCE->getImplicitObjectArgument();
2028	Object->printPretty(Out, /*Helper=*/nullptr, Info.Ctx.getPrintingPolicy(),
2029	/*Indentation=*/0);
2030	if (Object->getType()->isPointerType())
2031	Out << "->";
2032	else
2033	Out << ".";
2034	} else if (const auto *OCE =
2035	dyn_cast_if_present<CXXOperatorCallExpr>(Val: CallExpr)) {
2036	OCE->getArg(0)->printPretty(Out, /*Helper=*/nullptr,
2037	Info.Ctx.getPrintingPolicy(),
2038	/*Indentation=*/0);
2039	Out << ".";
2040	} else {
2041	APValue Val;
2042	This->moveInto(V&: Val);
2043	Val.printPretty(
2044	Out, Info.Ctx,
2045	Info.Ctx.getLValueReferenceType(T: This->Designator.MostDerivedType));
2046	Out << ".";
2047	}
2048	Callee->getNameForDiagnostic(OS&: Out, Policy: Info.Ctx.getPrintingPolicy(),
2049	/*Qualified=*/false);
2050	IsMemberCall = false;
2051	}
2052
2053	Out << '(';
2054
2055	for (FunctionDecl::param_const_iterator I = Callee->param_begin(),
2056	E = Callee->param_end(); I != E; ++I, ++ArgIndex) {
2057	if (ArgIndex > (unsigned)IsMemberCall)
2058	Out << ", ";
2059
2060	const ParmVarDecl *Param = *I;
2061	APValue *V = Info.getParamSlot(Call: Arguments, PVD: Param);
2062	if (V)
2063	V->printPretty(Out, Info.Ctx, Param->getType());
2064	else
2065	Out << "<...>";
2066
2067	if (ArgIndex == 0 && IsMemberCall)
2068	Out << "->" << *Callee << '(';
2069	}
2070
2071	Out << ')';
2072	}
2073
2074	/// Evaluate an expression to see if it had side-effects, and discard its
2075	/// result.
2076	/// \return \c true if the caller should keep evaluating.
2077	static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
2078	assert(!E->isValueDependent());
2079	APValue Scratch;
2080	if (!Evaluate(Result&: Scratch, Info, E))
2081	// We don't need the value, but we might have skipped a side effect here.
2082	return Info.noteSideEffect();
2083	return true;
2084	}
2085
2086	/// Should this call expression be treated as forming an opaque constant?
2087	static bool IsOpaqueConstantCall(const CallExpr *E) {
2088	unsigned Builtin = E->getBuiltinCallee();
2089	return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
2090	Builtin == Builtin::BI__builtin___NSStringMakeConstantString ||
2091	Builtin == Builtin::BI__builtin_ptrauth_sign_constant ||
2092	Builtin == Builtin::BI__builtin_function_start);
2093	}
2094
2095	static bool IsOpaqueConstantCall(const LValue &LVal) {
2096	const auto *BaseExpr =
2097	llvm::dyn_cast_if_present<CallExpr>(Val: LVal.Base.dyn_cast<const Expr *>());
2098	return BaseExpr && IsOpaqueConstantCall(E: BaseExpr);
2099	}
2100
2101	static bool IsGlobalLValue(APValue::LValueBase B) {
2102	// C++11 [expr.const]p3 An address constant expression is a prvalue core
2103	// constant expression of pointer type that evaluates to...
2104
2105	// ... a null pointer value, or a prvalue core constant expression of type
2106	// std::nullptr_t.
2107	if (!B)
2108	return true;
2109
2110	if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
2111	// ... the address of an object with static storage duration,
2112	if (const VarDecl *VD = dyn_cast<VarDecl>(Val: D))
2113	return VD->hasGlobalStorage();
2114	if (isa<TemplateParamObjectDecl>(Val: D))
2115	return true;
2116	// ... the address of a function,
2117	// ... the address of a GUID [MS extension],
2118	// ... the address of an unnamed global constant
2119	return isa<FunctionDecl, MSGuidDecl, UnnamedGlobalConstantDecl>(Val: D);
2120	}
2121
2122	if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>())
2123	return true;
2124
2125	const Expr *E = B.get<const Expr*>();
2126	switch (E->getStmtClass()) {
2127	default:
2128	return false;
2129	case Expr::CompoundLiteralExprClass: {
2130	const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(Val: E);
2131	return CLE->isFileScope() && CLE->isLValue();
2132	}
2133	case Expr::MaterializeTemporaryExprClass:
2134	// A materialized temporary might have been lifetime-extended to static
2135	// storage duration.
2136	return cast<MaterializeTemporaryExpr>(Val: E)->getStorageDuration() == SD_Static;
2137	// A string literal has static storage duration.
2138	case Expr::StringLiteralClass:
2139	case Expr::PredefinedExprClass:
2140	case Expr::ObjCStringLiteralClass:
2141	case Expr::ObjCEncodeExprClass:
2142	return true;
2143	case Expr::ObjCBoxedExprClass:
2144	return cast<ObjCBoxedExpr>(Val: E)->isExpressibleAsConstantInitializer();
2145	case Expr::CallExprClass:
2146	return IsOpaqueConstantCall(E: cast<CallExpr>(Val: E));
2147	// For GCC compatibility, &&label has static storage duration.
2148	case Expr::AddrLabelExprClass:
2149	return true;
2150	// A Block literal expression may be used as the initialization value for
2151	// Block variables at global or local static scope.
2152	case Expr::BlockExprClass:
2153	return !cast<BlockExpr>(Val: E)->getBlockDecl()->hasCaptures();
2154	// The APValue generated from a __builtin_source_location will be emitted as a
2155	// literal.
2156	case Expr::SourceLocExprClass:
2157	return true;
2158	case Expr::ImplicitValueInitExprClass:
2159	// FIXME:
2160	// We can never form an lvalue with an implicit value initialization as its
2161	// base through expression evaluation, so these only appear in one case: the
2162	// implicit variable declaration we invent when checking whether a constexpr
2163	// constructor can produce a constant expression. We must assume that such
2164	// an expression might be a global lvalue.
2165	return true;
2166	}
2167	}
2168
2169	static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
2170	return LVal.Base.dyn_cast<const ValueDecl*>();
2171	}
2172
2173	// Information about an LValueBase that is some kind of string.
2174	struct LValueBaseString {
2175	std::string ObjCEncodeStorage;
2176	StringRef Bytes;
2177	int CharWidth;
2178	};
2179
2180	// Gets the lvalue base of LVal as a string.
2181	static bool GetLValueBaseAsString(const EvalInfo &Info, const LValue &LVal,
2182	LValueBaseString &AsString) {
2183	const auto *BaseExpr = LVal.Base.dyn_cast<const Expr *>();
2184	if (!BaseExpr)
2185	return false;
2186
2187	// For ObjCEncodeExpr, we need to compute and store the string.
2188	if (const auto *EE = dyn_cast<ObjCEncodeExpr>(Val: BaseExpr)) {
2189	Info.Ctx.getObjCEncodingForType(T: EE->getEncodedType(),
2190	S&: AsString.ObjCEncodeStorage);
2191	AsString.Bytes = AsString.ObjCEncodeStorage;
2192	AsString.CharWidth = 1;
2193	return true;
2194	}
2195
2196	// Otherwise, we have a StringLiteral.
2197	const auto *Lit = dyn_cast<StringLiteral>(Val: BaseExpr);
2198	if (const auto *PE = dyn_cast<PredefinedExpr>(Val: BaseExpr))
2199	Lit = PE->getFunctionName();
2200
2201	if (!Lit)
2202	return false;
2203
2204	AsString.Bytes = Lit->getBytes();
2205	AsString.CharWidth = Lit->getCharByteWidth();
2206	return true;
2207	}
2208
2209	// Determine whether two string literals potentially overlap. This will be the
2210	// case if they agree on the values of all the bytes on the overlapping region
2211	// between them.
2212	//
2213	// The overlapping region is the portion of the two string literals that must
2214	// overlap in memory if the pointers actually point to the same address at
2215	// runtime. For example, if LHS is "abcdef" + 3 and RHS is "cdef\0gh" + 1 then
2216	// the overlapping region is "cdef\0", which in this case does agree, so the
2217	// strings are potentially overlapping. Conversely, for "foobar" + 3 versus
2218	// "bazbar" + 3, the overlapping region contains all of both strings, so they
2219	// are not potentially overlapping, even though they agree from the given
2220	// addresses onwards.
2221	//
2222	// See open core issue CWG2765 which is discussing the desired rule here.
2223	static bool ArePotentiallyOverlappingStringLiterals(const EvalInfo &Info,
2224	const LValue &LHS,
2225	const LValue &RHS) {
2226	LValueBaseString LHSString, RHSString;
2227	if (!GetLValueBaseAsString(Info, LVal: LHS, AsString&: LHSString) ||
2228	!GetLValueBaseAsString(Info, LVal: RHS, AsString&: RHSString))
2229	return false;
2230
2231	// This is the byte offset to the location of the first character of LHS
2232	// within RHS. We don't need to look at the characters of one string that
2233	// would appear before the start of the other string if they were merged.
2234	CharUnits Offset = RHS.Offset - LHS.Offset;
2235	if (Offset.isNegative()) {
2236	if (LHSString.Bytes.size() < (size_t)-Offset.getQuantity())
2237	return false;
2238	LHSString.Bytes = LHSString.Bytes.drop_front(N: -Offset.getQuantity());
2239	} else {
2240	if (RHSString.Bytes.size() < (size_t)Offset.getQuantity())
2241	return false;
2242	RHSString.Bytes = RHSString.Bytes.drop_front(N: Offset.getQuantity());
2243	}
2244
2245	bool LHSIsLonger = LHSString.Bytes.size() > RHSString.Bytes.size();
2246	StringRef Longer = LHSIsLonger ? LHSString.Bytes : RHSString.Bytes;
2247	StringRef Shorter = LHSIsLonger ? RHSString.Bytes : LHSString.Bytes;
2248	int ShorterCharWidth = (LHSIsLonger ? RHSString : LHSString).CharWidth;
2249
2250	// The null terminator isn't included in the string data, so check for it
2251	// manually. If the longer string doesn't have a null terminator where the
2252	// shorter string ends, they aren't potentially overlapping.
2253	for (int NullByte : llvm::seq(Size: ShorterCharWidth)) {
2254	if (Shorter.size() + NullByte >= Longer.size())
2255	break;
2256	if (Longer[Shorter.size() + NullByte])
2257	return false;
2258	}
2259
2260	// Otherwise, they're potentially overlapping if and only if the overlapping
2261	// region is the same.
2262	return Shorter == Longer.take_front(N: Shorter.size());
2263	}
2264
2265	static bool IsWeakLValue(const LValue &Value) {
2266	const ValueDecl *Decl = GetLValueBaseDecl(LVal: Value);
2267	return Decl && Decl->isWeak();
2268	}
2269
2270	static bool isZeroSized(const LValue &Value) {
2271	const ValueDecl *Decl = GetLValueBaseDecl(LVal: Value);
2272	if (isa_and_nonnull<VarDecl>(Val: Decl)) {
2273	QualType Ty = Decl->getType();
2274	if (Ty->isArrayType())
2275	return Ty->isIncompleteType() ||
2276	Decl->getASTContext().getTypeSize(Ty) == 0;
2277	}
2278	return false;
2279	}
2280
2281	static bool HasSameBase(const LValue &A, const LValue &B) {
2282	if (!A.getLValueBase())
2283	return !B.getLValueBase();
2284	if (!B.getLValueBase())
2285	return false;
2286
2287	if (A.getLValueBase().getOpaqueValue() !=
2288	B.getLValueBase().getOpaqueValue())
2289	return false;
2290
2291	return A.getLValueCallIndex() == B.getLValueCallIndex() &&
2292	A.getLValueVersion() == B.getLValueVersion();
2293	}
2294
2295	static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
2296	assert(Base && "no location for a null lvalue");
2297	const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
2298
2299	// For a parameter, find the corresponding call stack frame (if it still
2300	// exists), and point at the parameter of the function definition we actually
2301	// invoked.
2302	if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(Val: VD)) {
2303	unsigned Idx = PVD->getFunctionScopeIndex();
2304	for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller) {
2305	if (F->Arguments.CallIndex == Base.getCallIndex() &&
2306	F->Arguments.Version == Base.getVersion() && F->Callee &&
2307	Idx < F->Callee->getNumParams()) {
2308	VD = F->Callee->getParamDecl(i: Idx);
2309	break;
2310	}
2311	}
2312	}
2313
2314	if (VD)
2315	Info.Note(VD->getLocation(), diag::note_declared_at);
2316	else if (const Expr *E = Base.dyn_cast<const Expr*>())
2317	Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
2318	else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
2319	// FIXME: Produce a note for dangling pointers too.
2320	if (std::optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA))
2321	Info.Note((*Alloc)->AllocExpr->getExprLoc(),
2322	diag::note_constexpr_dynamic_alloc_here);
2323	}
2324
2325	// We have no information to show for a typeid(T) object.
2326	}
2327
2328	enum class CheckEvaluationResultKind {
2329	ConstantExpression,
2330	FullyInitialized,
2331	};
2332
2333	/// Materialized temporaries that we've already checked to determine if they're
2334	/// initializsed by a constant expression.
2335	using CheckedTemporaries =
2336	llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>;
2337
2338	static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2339	EvalInfo &Info, SourceLocation DiagLoc,
2340	QualType Type, const APValue &Value,
2341	ConstantExprKind Kind,
2342	const FieldDecl *SubobjectDecl,
2343	CheckedTemporaries &CheckedTemps);
2344
2345	/// Check that this reference or pointer core constant expression is a valid
2346	/// value for an address or reference constant expression. Return true if we
2347	/// can fold this expression, whether or not it's a constant expression.
2348	static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
2349	QualType Type, const LValue &LVal,
2350	ConstantExprKind Kind,
2351	CheckedTemporaries &CheckedTemps) {
2352	bool IsReferenceType = Type->isReferenceType();
2353
2354	APValue::LValueBase Base = LVal.getLValueBase();
2355	const SubobjectDesignator &Designator = LVal.getLValueDesignator();
2356
2357	const Expr *BaseE = Base.dyn_cast<const Expr *>();
2358	const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>();
2359
2360	// Additional restrictions apply in a template argument. We only enforce the
2361	// C++20 restrictions here; additional syntactic and semantic restrictions
2362	// are applied elsewhere.
2363	if (isTemplateArgument(Kind)) {
2364	int InvalidBaseKind = -1;
2365	StringRef Ident;
2366	if (Base.is<TypeInfoLValue>())
2367	InvalidBaseKind = 0;
2368	else if (isa_and_nonnull<StringLiteral>(Val: BaseE))
2369	InvalidBaseKind = 1;
2370	else if (isa_and_nonnull<MaterializeTemporaryExpr>(Val: BaseE) ||
2371	isa_and_nonnull<LifetimeExtendedTemporaryDecl>(Val: BaseVD))
2372	InvalidBaseKind = 2;
2373	else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(Val: BaseE)) {
2374	InvalidBaseKind = 3;
2375	Ident = PE->getIdentKindName();
2376	}
2377
2378	if (InvalidBaseKind != -1) {
2379	Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg)
2380	<< IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind
2381	<< Ident;
2382	return false;
2383	}
2384	}
2385
2386	if (auto *FD = dyn_cast_or_null<FunctionDecl>(Val: BaseVD);
2387	FD && FD->isImmediateFunction()) {
2388	Info.FFDiag(Loc, diag::note_consteval_address_accessible)
2389	<< !Type->isAnyPointerType();
2390	Info.Note(FD->getLocation(), diag::note_declared_at);
2391	return false;
2392	}
2393
2394	// Check that the object is a global. Note that the fake 'this' object we
2395	// manufacture when checking potential constant expressions is conservatively
2396	// assumed to be global here.
2397	if (!IsGlobalLValue(B: Base)) {
2398	if (Info.getLangOpts().CPlusPlus11) {
2399	Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
2400	<< IsReferenceType << !Designator.Entries.empty() << !!BaseVD
2401	<< BaseVD;
2402	auto *VarD = dyn_cast_or_null<VarDecl>(Val: BaseVD);
2403	if (VarD && VarD->isConstexpr()) {
2404	// Non-static local constexpr variables have unintuitive semantics:
2405	// constexpr int a = 1;
2406	// constexpr const int *p = &a;
2407	// ... is invalid because the address of 'a' is not constant. Suggest
2408	// adding a 'static' in this case.
2409	Info.Note(VarD->getLocation(), diag::note_constexpr_not_static)
2410	<< VarD
2411	<< FixItHint::CreateInsertion(VarD->getBeginLoc(), "static ");
2412	} else {
2413	NoteLValueLocation(Info, Base);
2414	}
2415	} else {
2416	Info.FFDiag(Loc);
2417	}
2418	// Don't allow references to temporaries to escape.
2419	return false;
2420	}
2421	assert((Info.checkingPotentialConstantExpression() ||
2422	LVal.getLValueCallIndex() == 0) &&
2423	"have call index for global lvalue");
2424
2425	if (LVal.allowConstexprUnknown()) {
2426	if (BaseVD) {
2427	Info.FFDiag(Loc, diag::note_constexpr_var_init_non_constant, 1) << BaseVD;
2428	NoteLValueLocation(Info, Base);
2429	} else {
2430	Info.FFDiag(Loc);
2431	}
2432	return false;
2433	}
2434
2435	if (Base.is<DynamicAllocLValue>()) {
2436	Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc)
2437	<< IsReferenceType << !Designator.Entries.empty();
2438	NoteLValueLocation(Info, Base);
2439	return false;
2440	}
2441
2442	if (BaseVD) {
2443	if (const VarDecl *Var = dyn_cast<const VarDecl>(Val: BaseVD)) {
2444	// Check if this is a thread-local variable.
2445	if (Var->getTLSKind())
2446	// FIXME: Diagnostic!
2447	return false;
2448
2449	// A dllimport variable never acts like a constant, unless we're
2450	// evaluating a value for use only in name mangling.
2451	if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>())
2452	// FIXME: Diagnostic!
2453	return false;
2454
2455	// In CUDA/HIP device compilation, only device side variables have
2456	// constant addresses.
2457	if (Info.getASTContext().getLangOpts().CUDA &&
2458	Info.getASTContext().getLangOpts().CUDAIsDevice &&
2459	Info.getASTContext().CUDAConstantEvalCtx.NoWrongSidedVars) {
2460	if ((!Var->hasAttr<CUDADeviceAttr>() &&
2461	!Var->hasAttr<CUDAConstantAttr>() &&
2462	!Var->getType()->isCUDADeviceBuiltinSurfaceType() &&
2463	!Var->getType()->isCUDADeviceBuiltinTextureType()) ||
2464	Var->hasAttr<HIPManagedAttr>())
2465	return false;
2466	}
2467	}
2468	if (const auto *FD = dyn_cast<const FunctionDecl>(Val: BaseVD)) {
2469	// __declspec(dllimport) must be handled very carefully:
2470	// We must never initialize an expression with the thunk in C++.
2471	// Doing otherwise would allow the same id-expression to yield
2472	// different addresses for the same function in different translation
2473	// units. However, this means that we must dynamically initialize the
2474	// expression with the contents of the import address table at runtime.
2475	//
2476	// The C language has no notion of ODR; furthermore, it has no notion of
2477	// dynamic initialization. This means that we are permitted to
2478	// perform initialization with the address of the thunk.
2479	if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind) &&
2480	FD->hasAttr<DLLImportAttr>())
2481	// FIXME: Diagnostic!
2482	return false;
2483	}
2484	} else if (const auto *MTE =
2485	dyn_cast_or_null<MaterializeTemporaryExpr>(Val: BaseE)) {
2486	if (CheckedTemps.insert(Ptr: MTE).second) {
2487	QualType TempType = getType(B: Base);
2488	if (TempType.isDestructedType()) {
2489	Info.FFDiag(MTE->getExprLoc(),
2490	diag::note_constexpr_unsupported_temporary_nontrivial_dtor)
2491	<< TempType;
2492	return false;
2493	}
2494
2495	APValue *V = MTE->getOrCreateValue(MayCreate: false);
2496	assert(V && "evasluation result refers to uninitialised temporary");
2497	if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
2498	Info, MTE->getExprLoc(), TempType, *V, Kind,
2499	/*SubobjectDecl=*/nullptr, CheckedTemps))
2500	return false;
2501	}
2502	}
2503
2504	// Allow address constant expressions to be past-the-end pointers. This is
2505	// an extension: the standard requires them to point to an object.
2506	if (!IsReferenceType)
2507	return true;
2508
2509	// A reference constant expression must refer to an object.
2510	if (!Base) {
2511	// FIXME: diagnostic
2512	Info.CCEDiag(Loc);
2513	return true;
2514	}
2515
2516	// Does this refer one past the end of some object?
2517	if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
2518	Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
2519	<< !Designator.Entries.empty() << !!BaseVD << BaseVD;
2520	NoteLValueLocation(Info, Base);
2521	}
2522
2523	return true;
2524	}
2525
2526	/// Member pointers are constant expressions unless they point to a
2527	/// non-virtual dllimport member function.
2528	static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
2529	SourceLocation Loc,
2530	QualType Type,
2531	const APValue &Value,
2532	ConstantExprKind Kind) {
2533	const ValueDecl *Member = Value.getMemberPointerDecl();
2534	const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Val: Member);
2535	if (!FD)
2536	return true;
2537	if (FD->isImmediateFunction()) {
2538	Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0;
2539	Info.Note(FD->getLocation(), diag::note_declared_at);
2540	return false;
2541	}
2542	return isForManglingOnly(Kind) || FD->isVirtual() ||
2543	!FD->hasAttr<DLLImportAttr>();
2544	}
2545
2546	/// Check that this core constant expression is of literal type, and if not,
2547	/// produce an appropriate diagnostic.
2548	static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
2549	const LValue *This = nullptr) {
2550	// The restriction to literal types does not exist in C++23 anymore.
2551	if (Info.getLangOpts().CPlusPlus23)
2552	return true;
2553
2554	if (!E->isPRValue() || E->getType()->isLiteralType(Ctx: Info.Ctx))
2555	return true;
2556
2557	// C++1y: A constant initializer for an object o [...] may also invoke
2558	// constexpr constructors for o and its subobjects even if those objects
2559	// are of non-literal class types.
2560	//
2561	// C++11 missed this detail for aggregates, so classes like this:
2562	// struct foo_t { union { int i; volatile int j; } u; };
2563	// are not (obviously) initializable like so:
2564	// __attribute__((__require_constant_initialization__))
2565	// static const foo_t x = {{0}};
2566	// because "i" is a subobject with non-literal initialization (due to the
2567	// volatile member of the union). See:
2568	// http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
2569	// Therefore, we use the C++1y behavior.
2570	if (This && Info.EvaluatingDecl == This->getLValueBase())
2571	return true;
2572
2573	// Prvalue constant expressions must be of literal types.
2574	if (Info.getLangOpts().CPlusPlus11)
2575	Info.FFDiag(E, diag::note_constexpr_nonliteral)
2576	<< E->getType();
2577	else
2578	Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
2579	return false;
2580	}
2581
2582	static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
2583	EvalInfo &Info, SourceLocation DiagLoc,
2584	QualType Type, const APValue &Value,
2585	ConstantExprKind Kind,
2586	const FieldDecl *SubobjectDecl,
2587	CheckedTemporaries &CheckedTemps) {
2588	if (!Value.hasValue()) {
2589	if (SubobjectDecl) {
2590	Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
2591	<< /*(name)*/ 1 << SubobjectDecl;
2592	Info.Note(SubobjectDecl->getLocation(),
2593	diag::note_constexpr_subobject_declared_here);
2594	} else {
2595	Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
2596	<< /*of type*/ 0 << Type;
2597	}
2598	return false;
2599	}
2600
2601	// We allow _Atomic(T) to be initialized from anything that T can be
2602	// initialized from.
2603	if (const AtomicType *AT = Type->getAs<AtomicType>())
2604	Type = AT->getValueType();
2605
2606	// Core issue 1454: For a literal constant expression of array or class type,
2607	// each subobject of its value shall have been initialized by a constant
2608	// expression.
2609	if (Value.isArray()) {
2610	QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
2611	for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
2612	if (!CheckEvaluationResult(CERK, Info, DiagLoc, Type: EltTy,
2613	Value: Value.getArrayInitializedElt(I), Kind,
2614	SubobjectDecl, CheckedTemps))
2615	return false;
2616	}
2617	if (!Value.hasArrayFiller())
2618	return true;
2619	return CheckEvaluationResult(CERK, Info, DiagLoc, Type: EltTy,
2620	Value: Value.getArrayFiller(), Kind, SubobjectDecl,
2621	CheckedTemps);
2622	}
2623	if (Value.isUnion() && Value.getUnionField()) {
2624	return CheckEvaluationResult(
2625	CERK, Info, DiagLoc, Value.getUnionField()->getType(),
2626	Value.getUnionValue(), Kind, Value.getUnionField(), CheckedTemps);
2627	}
2628	if (Value.isStruct()) {
2629	RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
2630	if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(Val: RD)) {
2631	unsigned BaseIndex = 0;
2632	for (const CXXBaseSpecifier &BS : CD->bases()) {
2633	const APValue &BaseValue = Value.getStructBase(i: BaseIndex);
2634	if (!BaseValue.hasValue()) {
2635	SourceLocation TypeBeginLoc = BS.getBaseTypeLoc();
2636	Info.FFDiag(TypeBeginLoc, diag::note_constexpr_uninitialized_base)
2637	<< BS.getType() << SourceRange(TypeBeginLoc, BS.getEndLoc());
2638	return false;
2639	}
2640	if (!CheckEvaluationResult(CERK, Info, DiagLoc, Type: BS.getType(), Value: BaseValue,
2641	Kind, /*SubobjectDecl=*/nullptr,
2642	CheckedTemps))
2643	return false;
2644	++BaseIndex;
2645	}
2646	}
2647	for (const auto *I : RD->fields()) {
2648	if (I->isUnnamedBitField())
2649	continue;
2650
2651	if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(),
2652	Value.getStructField(i: I->getFieldIndex()), Kind,
2653	I, CheckedTemps))
2654	return false;
2655	}
2656	}
2657
2658	if (Value.isLValue() &&
2659	CERK == CheckEvaluationResultKind::ConstantExpression) {
2660	LValue LVal;
2661	LVal.setFrom(Ctx&: Info.Ctx, V: Value);
2662	return CheckLValueConstantExpression(Info, Loc: DiagLoc, Type, LVal, Kind,
2663	CheckedTemps);
2664	}
2665
2666	if (Value.isMemberPointer() &&
2667	CERK == CheckEvaluationResultKind::ConstantExpression)
2668	return CheckMemberPointerConstantExpression(Info, Loc: DiagLoc, Type, Value, Kind);
2669
2670	// Everything else is fine.
2671	return true;
2672	}
2673
2674	/// Check that this core constant expression value is a valid value for a
2675	/// constant expression. If not, report an appropriate diagnostic. Does not
2676	/// check that the expression is of literal type.
2677	static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc,
2678	QualType Type, const APValue &Value,
2679	ConstantExprKind Kind) {
2680	// Nothing to check for a constant expression of type 'cv void'.
2681	if (Type->isVoidType())
2682	return true;
2683
2684	CheckedTemporaries CheckedTemps;
2685	return CheckEvaluationResult(CERK: CheckEvaluationResultKind::ConstantExpression,
2686	Info, DiagLoc, Type, Value, Kind,
2687	/*SubobjectDecl=*/nullptr, CheckedTemps);
2688	}
2689
2690	/// Check that this evaluated value is fully-initialized and can be loaded by
2691	/// an lvalue-to-rvalue conversion.
2692	static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc,
2693	QualType Type, const APValue &Value) {
2694	CheckedTemporaries CheckedTemps;
2695	return CheckEvaluationResult(
2696	CERK: CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value,
2697	Kind: ConstantExprKind::Normal, /*SubobjectDecl=*/nullptr, CheckedTemps);
2698	}
2699
2700	/// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless
2701	/// "the allocated storage is deallocated within the evaluation".
2702	static bool CheckMemoryLeaks(EvalInfo &Info) {
2703	if (!Info.HeapAllocs.empty()) {
2704	// We can still fold to a constant despite a compile-time memory leak,
2705	// so long as the heap allocation isn't referenced in the result (we check
2706	// that in CheckConstantExpression).
2707	Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr,
2708	diag::note_constexpr_memory_leak)
2709	<< unsigned(Info.HeapAllocs.size() - 1);
2710	}
2711	return true;
2712	}
2713
2714	static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
2715	// A null base expression indicates a null pointer. These are always
2716	// evaluatable, and they are false unless the offset is zero.
2717	if (!Value.getLValueBase()) {
2718	// TODO: Should a non-null pointer with an offset of zero evaluate to true?
2719	Result = !Value.getLValueOffset().isZero();
2720	return true;
2721	}
2722
2723	// We have a non-null base. These are generally known to be true, but if it's
2724	// a weak declaration it can be null at runtime.
2725	Result = true;
2726	const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
2727	return !Decl || !Decl->isWeak();
2728	}
2729
2730	static bool HandleConversionToBool(const APValue &Val, bool &Result) {
2731	// TODO: This function should produce notes if it fails.
2732	switch (Val.getKind()) {
2733	case APValue::None:
2734	case APValue::Indeterminate:
2735	return false;
2736	case APValue::Int:
2737	Result = Val.getInt().getBoolValue();
2738	return true;
2739	case APValue::FixedPoint:
2740	Result = Val.getFixedPoint().getBoolValue();
2741	return true;
2742	case APValue::Float:
2743	Result = !Val.getFloat().isZero();
2744	return true;
2745	case APValue::ComplexInt:
2746	Result = Val.getComplexIntReal().getBoolValue() ||
2747	Val.getComplexIntImag().getBoolValue();
2748	return true;
2749	case APValue::ComplexFloat:
2750	Result = !Val.getComplexFloatReal().isZero() ||
2751	!Val.getComplexFloatImag().isZero();
2752	return true;
2753	case APValue::LValue:
2754	return EvalPointerValueAsBool(Value: Val, Result);
2755	case APValue::MemberPointer:
2756	if (Val.getMemberPointerDecl() && Val.getMemberPointerDecl()->isWeak()) {
2757	return false;
2758	}
2759	Result = Val.getMemberPointerDecl();
2760	return true;
2761	case APValue::Vector:
2762	case APValue::Array:
2763	case APValue::Struct:
2764	case APValue::Union:
2765	case APValue::AddrLabelDiff:
2766	return false;
2767	}
2768
2769	llvm_unreachable("unknown APValue kind");
2770	}
2771
2772	static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
2773	EvalInfo &Info) {
2774	assert(!E->isValueDependent());
2775	assert(E->isPRValue() && "missing lvalue-to-rvalue conv in bool condition");
2776	APValue Val;
2777	if (!Evaluate(Result&: Val, Info, E))
2778	return false;
2779	return HandleConversionToBool(Val, Result);
2780	}
2781
2782	template<typename T>
2783	static bool HandleOverflow(EvalInfo &Info, const Expr *E,
2784	const T &SrcValue, QualType DestType) {
2785	Info.CCEDiag(E, diag::note_constexpr_overflow)
2786	<< SrcValue << DestType;
2787	return Info.noteUndefinedBehavior();
2788	}
2789
2790	static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
2791	QualType SrcType, const APFloat &Value,
2792	QualType DestType, APSInt &Result) {
2793	unsigned DestWidth = Info.Ctx.getIntWidth(T: DestType);
2794	// Determine whether we are converting to unsigned or signed.
2795	bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
2796
2797	Result = APSInt(DestWidth, !DestSigned);
2798	bool ignored;
2799	if (Value.convertToInteger(Result, RM: llvm::APFloat::rmTowardZero, IsExact: &ignored)
2800	& APFloat::opInvalidOp)
2801	return HandleOverflow(Info, E, SrcValue: Value, DestType);
2802	return true;
2803	}
2804
2805	/// Get rounding mode to use in evaluation of the specified expression.
2806	///
2807	/// If rounding mode is unknown at compile time, still try to evaluate the
2808	/// expression. If the result is exact, it does not depend on rounding mode.
2809	/// So return "tonearest" mode instead of "dynamic".
2810	static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E) {
2811	llvm::RoundingMode RM =
2812	E->getFPFeaturesInEffect(LO: Info.Ctx.getLangOpts()).getRoundingMode();
2813	if (RM == llvm::RoundingMode::Dynamic)
2814	RM = llvm::RoundingMode::NearestTiesToEven;
2815	return RM;
2816	}
2817
2818	/// Check if the given evaluation result is allowed for constant evaluation.
2819	static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E,
2820	APFloat::opStatus St) {
2821	// In a constant context, assume that any dynamic rounding mode or FP
2822	// exception state matches the default floating-point environment.
2823	if (Info.InConstantContext)
2824	return true;
2825
2826	FPOptions FPO = E->getFPFeaturesInEffect(LO: Info.Ctx.getLangOpts());
2827	if ((St & APFloat::opInexact) &&
2828	FPO.getRoundingMode() == llvm::RoundingMode::Dynamic) {
2829	// Inexact result means that it depends on rounding mode. If the requested
2830	// mode is dynamic, the evaluation cannot be made in compile time.
2831	Info.FFDiag(E, diag::note_constexpr_dynamic_rounding);
2832	return false;
2833	}
2834
2835	if ((St != APFloat::opOK) &&
2836	(FPO.getRoundingMode() == llvm::RoundingMode::Dynamic ||
2837	FPO.getExceptionMode() != LangOptions::FPE_Ignore ||
2838	FPO.getAllowFEnvAccess())) {
2839	Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
2840	return false;
2841	}
2842
2843	if ((St & APFloat::opStatus::opInvalidOp) &&
2844	FPO.getExceptionMode() != LangOptions::FPE_Ignore) {
2845	// There is no usefully definable result.
2846	Info.FFDiag(E);
2847	return false;
2848	}
2849
2850	// FIXME: if:
2851	// - evaluation triggered other FP exception, and
2852	// - exception mode is not "ignore", and
2853	// - the expression being evaluated is not a part of global variable
2854	// initializer,
2855	// the evaluation probably need to be rejected.
2856	return true;
2857	}
2858
2859	static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
2860	QualType SrcType, QualType DestType,
2861	APFloat &Result) {
2862	assert((isa<CastExpr>(E) || isa<CompoundAssignOperator>(E) ||
2863	isa<ConvertVectorExpr>(E)) &&
2864	"HandleFloatToFloatCast has been checked with only CastExpr, "
2865	"CompoundAssignOperator and ConvertVectorExpr. Please either validate "
2866	"the new expression or address the root cause of this usage.");
2867	llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2868	APFloat::opStatus St;
2869	APFloat Value = Result;
2870	bool ignored;
2871	St = Result.convert(ToSemantics: Info.Ctx.getFloatTypeSemantics(T: DestType), RM, losesInfo: &ignored);
2872	return checkFloatingPointResult(Info, E, St);
2873	}
2874
2875	static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
2876	QualType DestType, QualType SrcType,
2877	const APSInt &Value) {
2878	unsigned DestWidth = Info.Ctx.getIntWidth(T: DestType);
2879	// Figure out if this is a truncate, extend or noop cast.
2880	// If the input is signed, do a sign extend, noop, or truncate.
2881	APSInt Result = Value.extOrTrunc(width: DestWidth);
2882	Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
2883	if (DestType->isBooleanType())
2884	Result = Value.getBoolValue();
2885	return Result;
2886	}
2887
2888	static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
2889	const FPOptions FPO,
2890	QualType SrcType, const APSInt &Value,
2891	QualType DestType, APFloat &Result) {
2892	Result = APFloat(Info.Ctx.getFloatTypeSemantics(T: DestType), 1);
2893	llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
2894	APFloat::opStatus St = Result.convertFromAPInt(Input: Value, IsSigned: Value.isSigned(), RM);
2895	return checkFloatingPointResult(Info, E, St);
2896	}
2897
2898	static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
2899	APValue &Value, const FieldDecl *FD) {
2900	assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield");
2901
2902	if (!Value.isInt()) {
2903	// Trying to store a pointer-cast-to-integer into a bitfield.
2904	// FIXME: In this case, we should provide the diagnostic for casting
2905	// a pointer to an integer.
2906	assert(Value.isLValue() && "integral value neither int nor lvalue?");
2907	Info.FFDiag(E);
2908	return false;
2909	}
2910
2911	APSInt &Int = Value.getInt();
2912	unsigned OldBitWidth = Int.getBitWidth();
2913	unsigned NewBitWidth = FD->getBitWidthValue();
2914	if (NewBitWidth < OldBitWidth)
2915	Int = Int.trunc(width: NewBitWidth).extend(width: OldBitWidth);
2916	return true;
2917	}
2918
2919	/// Perform the given integer operation, which is known to need at most BitWidth
2920	/// bits, and check for overflow in the original type (if that type was not an
2921	/// unsigned type).
2922	template<typename Operation>
2923	static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
2924	const APSInt &LHS, const APSInt &RHS,
2925	unsigned BitWidth, Operation Op,
2926	APSInt &Result) {
2927	if (LHS.isUnsigned()) {
2928	Result = Op(LHS, RHS);
2929	return true;
2930	}
2931
2932	APSInt Value(Op(LHS.extend(width: BitWidth), RHS.extend(width: BitWidth)), false);
2933	Result = Value.trunc(width: LHS.getBitWidth());
2934	if (Result.extend(width: BitWidth) != Value) {
2935	if (Info.checkingForUndefinedBehavior())
2936	Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
2937	diag::warn_integer_constant_overflow)
2938	<< toString(Result, 10, Result.isSigned(), /*formatAsCLiteral=*/false,
2939	/*UpperCase=*/true, /*InsertSeparators=*/true)
2940	<< E->getType() << E->getSourceRange();
2941	return HandleOverflow(Info, E, SrcValue: Value, DestType: E->getType());
2942	}
2943	return true;
2944	}
2945
2946	/// Perform the given binary integer operation.
2947	static bool handleIntIntBinOp(EvalInfo &Info, const BinaryOperator *E,
2948	const APSInt &LHS, BinaryOperatorKind Opcode,
2949	APSInt RHS, APSInt &Result) {
2950	bool HandleOverflowResult = true;
2951	switch (Opcode) {
2952	default:
2953	Info.FFDiag(E);
2954	return false;
2955	case BO_Mul:
2956	return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
2957	std::multiplies<APSInt>(), Result);
2958	case BO_Add:
2959	return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2960	std::plus<APSInt>(), Result);
2961	case BO_Sub:
2962	return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
2963	std::minus<APSInt>(), Result);
2964	case BO_And: Result = LHS & RHS; return true;
2965	case BO_Xor: Result = LHS ^ RHS; return true;
2966	case BO_Or: Result = LHS | RHS; return true;
2967	case BO_Div:
2968	case BO_Rem:
2969	if (RHS == 0) {
2970	Info.FFDiag(E, diag::note_expr_divide_by_zero)
2971	<< E->getRHS()->getSourceRange();
2972	return false;
2973	}
2974	// Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
2975	// this operation and gives the two's complement result.
2976	if (RHS.isNegative() && RHS.isAllOnes() && LHS.isSigned() &&
2977	LHS.isMinSignedValue())
2978	HandleOverflowResult = HandleOverflow(
2979	Info, E, -LHS.extend(width: LHS.getBitWidth() + 1), E->getType());
2980	Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
2981	return HandleOverflowResult;
2982	case BO_Shl: {
2983	if (Info.getLangOpts().OpenCL)
2984	// OpenCL 6.3j: shift values are effectively % word size of LHS.
2985	RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
2986	static_cast<uint64_t>(LHS.getBitWidth() - 1)),
2987	RHS.isUnsigned());
2988	else if (RHS.isSigned() && RHS.isNegative()) {
2989	// During constant-folding, a negative shift is an opposite shift. Such
2990	// a shift is not a constant expression.
2991	Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
2992	if (!Info.noteUndefinedBehavior())
2993	return false;
2994	RHS = -RHS;
2995	goto shift_right;
2996	}
2997	shift_left:
2998	// C++11 [expr.shift]p1: Shift width must be less than the bit width of
2999	// the shifted type.
3000	unsigned SA = (unsigned) RHS.getLimitedValue(Limit: LHS.getBitWidth()-1);
3001	if (SA != RHS) {
3002	Info.CCEDiag(E, diag::note_constexpr_large_shift)
3003	<< RHS << E->getType() << LHS.getBitWidth();
3004	if (!Info.noteUndefinedBehavior())
3005	return false;
3006	} else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) {
3007	// C++11 [expr.shift]p2: A signed left shift must have a non-negative
3008	// operand, and must not overflow the corresponding unsigned type.
3009	// C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to
3010	// E1 x 2^E2 module 2^N.
3011	if (LHS.isNegative()) {
3012	Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
3013	if (!Info.noteUndefinedBehavior())
3014	return false;
3015	} else if (LHS.countl_zero() < SA) {
3016	Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
3017	if (!Info.noteUndefinedBehavior())
3018	return false;
3019	}
3020	}
3021	Result = LHS << SA;
3022	return true;
3023	}
3024	case BO_Shr: {
3025	if (Info.getLangOpts().OpenCL)
3026	// OpenCL 6.3j: shift values are effectively % word size of LHS.
3027	RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
3028	static_cast<uint64_t>(LHS.getBitWidth() - 1)),
3029	RHS.isUnsigned());
3030	else if (RHS.isSigned() && RHS.isNegative()) {
3031	// During constant-folding, a negative shift is an opposite shift. Such a
3032	// shift is not a constant expression.
3033	Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
3034	if (!Info.noteUndefinedBehavior())
3035	return false;
3036	RHS = -RHS;
3037	goto shift_left;
3038	}
3039	shift_right:
3040	// C++11 [expr.shift]p1: Shift width must be less than the bit width of the
3041	// shifted type.
3042	unsigned SA = (unsigned) RHS.getLimitedValue(Limit: LHS.getBitWidth()-1);
3043	if (SA != RHS) {
3044	Info.CCEDiag(E, diag::note_constexpr_large_shift)
3045	<< RHS << E->getType() << LHS.getBitWidth();
3046	if (!Info.noteUndefinedBehavior())
3047	return false;
3048	}
3049
3050	Result = LHS >> SA;
3051	return true;
3052	}
3053
3054	case BO_LT: Result = LHS < RHS; return true;
3055	case BO_GT: Result = LHS > RHS; return true;
3056	case BO_LE: Result = LHS <= RHS; return true;
3057	case BO_GE: Result = LHS >= RHS; return true;
3058	case BO_EQ: Result = LHS == RHS; return true;
3059	case BO_NE: Result = LHS != RHS; return true;
3060	case BO_Cmp:
3061	llvm_unreachable("BO_Cmp should be handled elsewhere");
3062	}
3063	}
3064
3065	/// Perform the given binary floating-point operation, in-place, on LHS.
3066	static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E,
3067	APFloat &LHS, BinaryOperatorKind Opcode,
3068	const APFloat &RHS) {
3069	llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
3070	APFloat::opStatus St;
3071	switch (Opcode) {
3072	default:
3073	Info.FFDiag(E);
3074	return false;
3075	case BO_Mul:
3076	St = LHS.multiply(RHS, RM);
3077	break;
3078	case BO_Add:
3079	St = LHS.add(RHS, RM);
3080	break;
3081	case BO_Sub:
3082	St = LHS.subtract(RHS, RM);
3083	break;
3084	case BO_Div:
3085	// [expr.mul]p4:
3086	// If the second operand of / or % is zero the behavior is undefined.
3087	if (RHS.isZero())
3088	Info.CCEDiag(E, diag::note_expr_divide_by_zero);
3089	St = LHS.divide(RHS, RM);
3090	break;
3091	}
3092
3093	// [expr.pre]p4:
3094	// If during the evaluation of an expression, the result is not
3095	// mathematically defined [...], the behavior is undefined.
3096	// FIXME: C++ rules require us to not conform to IEEE 754 here.
3097	if (LHS.isNaN()) {
3098	Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
3099	return Info.noteUndefinedBehavior();
3100	}
3101
3102	return checkFloatingPointResult(Info, E, St);
3103	}
3104
3105	static bool handleLogicalOpForVector(const APInt &LHSValue,
3106	BinaryOperatorKind Opcode,
3107	const APInt &RHSValue, APInt &Result) {
3108	bool LHS = (LHSValue != 0);
3109	bool RHS = (RHSValue != 0);
3110
3111	if (Opcode == BO_LAnd)
3112	Result = LHS && RHS;
3113	else
3114	Result = LHS || RHS;
3115	return true;
3116	}
3117	static bool handleLogicalOpForVector(const APFloat &LHSValue,
3118	BinaryOperatorKind Opcode,
3119	const APFloat &RHSValue, APInt &Result) {
3120	bool LHS = !LHSValue.isZero();
3121	bool RHS = !RHSValue.isZero();
3122
3123	if (Opcode == BO_LAnd)
3124	Result = LHS && RHS;
3125	else
3126	Result = LHS || RHS;
3127	return true;
3128	}
3129
3130	static bool handleLogicalOpForVector(const APValue &LHSValue,
3131	BinaryOperatorKind Opcode,
3132	const APValue &RHSValue, APInt &Result) {
3133	// The result is always an int type, however operands match the first.
3134	if (LHSValue.getKind() == APValue::Int)
3135	return handleLogicalOpForVector(LHSValue: LHSValue.getInt(), Opcode,
3136	RHSValue: RHSValue.getInt(), Result);
3137	assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
3138	return handleLogicalOpForVector(LHSValue: LHSValue.getFloat(), Opcode,
3139	RHSValue: RHSValue.getFloat(), Result);
3140	}
3141
3142	template <typename APTy>
3143	static bool
3144	handleCompareOpForVectorHelper(const APTy &LHSValue, BinaryOperatorKind Opcode,
3145	const APTy &RHSValue, APInt &Result) {
3146	switch (Opcode) {
3147	default:
3148	llvm_unreachable("unsupported binary operator");
3149	case BO_EQ:
3150	Result = (LHSValue == RHSValue);
3151	break;
3152	case BO_NE:
3153	Result = (LHSValue != RHSValue);
3154	break;
3155	case BO_LT:
3156	Result = (LHSValue < RHSValue);
3157	break;
3158	case BO_GT:
3159	Result = (LHSValue > RHSValue);
3160	break;
3161	case BO_LE:
3162	Result = (LHSValue <= RHSValue);
3163	break;
3164	case BO_GE:
3165	Result = (LHSValue >= RHSValue);
3166	break;
3167	}
3168
3169	// The boolean operations on these vector types use an instruction that
3170	// results in a mask of '-1' for the 'truth' value. Ensure that we negate 1
3171	// to -1 to make sure that we produce the correct value.
3172	Result.negate();
3173
3174	return true;
3175	}
3176
3177	static bool handleCompareOpForVector(const APValue &LHSValue,
3178	BinaryOperatorKind Opcode,
3179	const APValue &RHSValue, APInt &Result) {
3180	// The result is always an int type, however operands match the first.
3181	if (LHSValue.getKind() == APValue::Int)
3182	return handleCompareOpForVectorHelper(LHSValue: LHSValue.getInt(), Opcode,
3183	RHSValue: RHSValue.getInt(), Result);
3184	assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
3185	return handleCompareOpForVectorHelper(LHSValue: LHSValue.getFloat(), Opcode,
3186	RHSValue: RHSValue.getFloat(), Result);
3187	}
3188
3189	// Perform binary operations for vector types, in place on the LHS.
3190	static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E,
3191	BinaryOperatorKind Opcode,
3192	APValue &LHSValue,
3193	const APValue &RHSValue) {
3194	assert(Opcode != BO_PtrMemD && Opcode != BO_PtrMemI &&
3195	"Operation not supported on vector types");
3196
3197	const auto *VT = E->getType()->castAs<VectorType>();
3198	unsigned NumElements = VT->getNumElements();
3199	QualType EltTy = VT->getElementType();
3200
3201	// In the cases (typically C as I've observed) where we aren't evaluating
3202	// constexpr but are checking for cases where the LHS isn't yet evaluatable,
3203	// just give up.
3204	if (!LHSValue.isVector()) {
3205	assert(LHSValue.isLValue() &&
3206	"A vector result that isn't a vector OR uncalculated LValue");
3207	Info.FFDiag(E);
3208	return false;
3209	}
3210
3211	assert(LHSValue.getVectorLength() == NumElements &&
3212	RHSValue.getVectorLength() == NumElements && "Different vector sizes");
3213
3214	SmallVector<APValue, 4> ResultElements;
3215
3216	for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum) {
3217	APValue LHSElt = LHSValue.getVectorElt(I: EltNum);
3218	APValue RHSElt = RHSValue.getVectorElt(I: EltNum);
3219
3220	if (EltTy->isIntegerType()) {
3221	APSInt EltResult{Info.Ctx.getIntWidth(T: EltTy),
3222	EltTy->isUnsignedIntegerType()};
3223	bool Success = true;
3224
3225	if (BinaryOperator::isLogicalOp(Opc: Opcode))
3226	Success = handleLogicalOpForVector(LHSValue: LHSElt, Opcode, RHSValue: RHSElt, Result&: EltResult);
3227	else if (BinaryOperator::isComparisonOp(Opc: Opcode))
3228	Success = handleCompareOpForVector(LHSValue: LHSElt, Opcode, RHSValue: RHSElt, Result&: EltResult);
3229	else
3230	Success = handleIntIntBinOp(Info, E, LHS: LHSElt.getInt(), Opcode,
3231	RHS: RHSElt.getInt(), Result&: EltResult);
3232
3233	if (!Success) {
3234	Info.FFDiag(E);
3235	return false;
3236	}
3237	ResultElements.emplace_back(Args&: EltResult);
3238
3239	} else if (EltTy->isFloatingType()) {
3240	assert(LHSElt.getKind() == APValue::Float &&
3241	RHSElt.getKind() == APValue::Float &&
3242	"Mismatched LHS/RHS/Result Type");
3243	APFloat LHSFloat = LHSElt.getFloat();
3244
3245	if (!handleFloatFloatBinOp(Info, E, LHS&: LHSFloat, Opcode,
3246	RHS: RHSElt.getFloat())) {
3247	Info.FFDiag(E);
3248	return false;
3249	}
3250
3251	ResultElements.emplace_back(Args&: LHSFloat);
3252	}
3253	}
3254
3255	LHSValue = APValue(ResultElements.data(), ResultElements.size());
3256	return true;
3257	}
3258
3259	/// Cast an lvalue referring to a base subobject to a derived class, by
3260	/// truncating the lvalue's path to the given length.
3261	static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
3262	const RecordDecl *TruncatedType,
3263	unsigned TruncatedElements) {
3264	SubobjectDesignator &D = Result.Designator;
3265
3266	// Check we actually point to a derived class object.
3267	if (TruncatedElements == D.Entries.size())
3268	return true;
3269	assert(TruncatedElements >= D.MostDerivedPathLength &&
3270	"not casting to a derived class");
3271	if (!Result.checkSubobject(Info, E, CSK: CSK_Derived))
3272	return false;
3273
3274	// Truncate the path to the subobject, and remove any derived-to-base offsets.
3275	const RecordDecl *RD = TruncatedType;
3276	for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
3277	if (RD->isInvalidDecl()) return false;
3278	const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(D: RD);
3279	const CXXRecordDecl *Base = getAsBaseClass(E: D.Entries[I]);
3280	if (isVirtualBaseClass(E: D.Entries[I]))
3281	Result.Offset -= Layout.getVBaseClassOffset(VBase: Base);
3282	else
3283	Result.Offset -= Layout.getBaseClassOffset(Base);
3284	RD = Base;
3285	}
3286	D.Entries.resize(N: TruncatedElements);
3287	return true;
3288	}
3289
3290	static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3291	const CXXRecordDecl *Derived,
3292	const CXXRecordDecl *Base,
3293	const ASTRecordLayout *RL = nullptr) {
3294	if (!RL) {
3295	if (Derived->isInvalidDecl()) return false;
3296	RL = &Info.Ctx.getASTRecordLayout(Derived);
3297	}
3298
3299	Obj.addDecl(Info, E, Base, /*Virtual*/ false);
3300	Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
3301	return true;
3302	}
3303
3304	static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
3305	const CXXRecordDecl *DerivedDecl,
3306	const CXXBaseSpecifier *Base) {
3307	const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
3308
3309	if (!Base->isVirtual())
3310	return HandleLValueDirectBase(Info, E, Obj, Derived: DerivedDecl, Base: BaseDecl);
3311
3312	SubobjectDesignator &D = Obj.Designator;
3313	if (D.Invalid)
3314	return false;
3315
3316	// Extract most-derived object and corresponding type.
3317	// FIXME: After implementing P2280R4 it became possible to get references
3318	// here. We do MostDerivedType->getAsCXXRecordDecl() in several other
3319	// locations and if we see crashes in those locations in the future
3320	// it may make more sense to move this fix into Lvalue::set.
3321	DerivedDecl = D.MostDerivedType.getNonReferenceType()->getAsCXXRecordDecl();
3322	if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
3323	return false;
3324
3325	// Find the virtual base class.
3326	if (DerivedDecl->isInvalidDecl()) return false;
3327	const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
3328	Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
3329	Obj.getLValueOffset() += Layout.getVBaseClassOffset(VBase: BaseDecl);
3330	return true;
3331	}
3332
3333	static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
3334	QualType Type, LValue &Result) {
3335	for (CastExpr::path_const_iterator PathI = E->path_begin(),
3336	PathE = E->path_end();
3337	PathI != PathE; ++PathI) {
3338	if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
3339	*PathI))
3340	return false;
3341	Type = (*PathI)->getType();
3342	}
3343	return true;
3344	}
3345
3346	/// Cast an lvalue referring to a derived class to a known base subobject.
3347	static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result,
3348	const CXXRecordDecl *DerivedRD,
3349	const CXXRecordDecl *BaseRD) {
3350	CXXBasePaths Paths(/*FindAmbiguities=*/false,
3351	/*RecordPaths=*/true, /*DetectVirtual=*/false);
3352	if (!DerivedRD->isDerivedFrom(Base: BaseRD, Paths))
3353	llvm_unreachable("Class must be derived from the passed in base class!");
3354
3355	for (CXXBasePathElement &Elem : Paths.front())
3356	if (!HandleLValueBase(Info, E, Obj&: Result, DerivedDecl: Elem.Class, Base: Elem.Base))
3357	return false;
3358	return true;
3359	}
3360
3361	/// Update LVal to refer to the given field, which must be a member of the type
3362	/// currently described by LVal.
3363	static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
3364	const FieldDecl *FD,
3365	const ASTRecordLayout *RL = nullptr) {
3366	if (!RL) {
3367	if (FD->getParent()->isInvalidDecl()) return false;
3368	RL = &Info.Ctx.getASTRecordLayout(D: FD->getParent());
3369	}
3370
3371	unsigned I = FD->getFieldIndex();
3372	LVal.addDecl(Info, E, FD);
3373	LVal.adjustOffset(N: Info.Ctx.toCharUnitsFromBits(BitSize: RL->getFieldOffset(FieldNo: I)));
3374	return true;
3375	}
3376
3377	/// Update LVal to refer to the given indirect field.
3378	static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
3379	LValue &LVal,
3380	const IndirectFieldDecl *IFD) {
3381	for (const auto *C : IFD->chain())
3382	if (!HandleLValueMember(Info, E, LVal, FD: cast<FieldDecl>(Val: C)))
3383	return false;
3384	return true;
3385	}
3386
3387	enum class SizeOfType {
3388	SizeOf,
3389	DataSizeOf,
3390	};
3391
3392	/// Get the size of the given type in char units.
3393	static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc, QualType Type,
3394	CharUnits &Size, SizeOfType SOT = SizeOfType::SizeOf) {
3395	// sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
3396	// extension.
3397	if (Type->isVoidType() || Type->isFunctionType()) {
3398	Size = CharUnits::One();
3399	return true;
3400	}
3401
3402	if (Type->isDependentType()) {
3403	Info.FFDiag(Loc);
3404	return false;
3405	}
3406
3407	if (!Type->isConstantSizeType()) {
3408	// sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
3409	// FIXME: Better diagnostic.
3410	Info.FFDiag(Loc);
3411	return false;
3412	}
3413
3414	if (SOT == SizeOfType::SizeOf)
3415	Size = Info.Ctx.getTypeSizeInChars(T: Type);
3416	else
3417	Size = Info.Ctx.getTypeInfoDataSizeInChars(T: Type).Width;
3418	return true;
3419	}
3420
3421	/// Update a pointer value to model pointer arithmetic.
3422	/// \param Info - Information about the ongoing evaluation.
3423	/// \param E - The expression being evaluated, for diagnostic purposes.
3424	/// \param LVal - The pointer value to be updated.
3425	/// \param EltTy - The pointee type represented by LVal.
3426	/// \param Adjustment - The adjustment, in objects of type EltTy, to add.
3427	static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3428	LValue &LVal, QualType EltTy,
3429	APSInt Adjustment) {
3430	CharUnits SizeOfPointee;
3431	if (!HandleSizeof(Info, Loc: E->getExprLoc(), Type: EltTy, Size&: SizeOfPointee))
3432	return false;
3433
3434	LVal.adjustOffsetAndIndex(Info, E, Index: Adjustment, ElementSize: SizeOfPointee);
3435	return true;
3436	}
3437
3438	static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
3439	LValue &LVal, QualType EltTy,
3440	int64_t Adjustment) {
3441	return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
3442	Adjustment: APSInt::get(X: Adjustment));
3443	}
3444
3445	/// Update an lvalue to refer to a component of a complex number.
3446	/// \param Info - Information about the ongoing evaluation.
3447	/// \param LVal - The lvalue to be updated.
3448	/// \param EltTy - The complex number's component type.
3449	/// \param Imag - False for the real component, true for the imaginary.
3450	static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
3451	LValue &LVal, QualType EltTy,
3452	bool Imag) {
3453	if (Imag) {
3454	CharUnits SizeOfComponent;
3455	if (!HandleSizeof(Info, Loc: E->getExprLoc(), Type: EltTy, Size&: SizeOfComponent))
3456	return false;
3457	LVal.Offset += SizeOfComponent;
3458	}
3459	LVal.addComplex(Info, E, EltTy, Imag);
3460	return true;
3461	}
3462
3463	static bool HandleLValueVectorElement(EvalInfo &Info, const Expr *E,
3464	LValue &LVal, QualType EltTy,
3465	uint64_t Size, uint64_t Idx) {
3466	if (Idx) {
3467	CharUnits SizeOfElement;
3468	if (!HandleSizeof(Info, Loc: E->getExprLoc(), Type: EltTy, Size&: SizeOfElement))
3469	return false;
3470	LVal.Offset += SizeOfElement * Idx;
3471	}
3472	LVal.addVectorElement(Info, E, EltTy, Size, Idx);
3473	return true;
3474	}
3475
3476	/// Try to evaluate the initializer for a variable declaration.
3477	///
3478	/// \param Info Information about the ongoing evaluation.
3479	/// \param E An expression to be used when printing diagnostics.
3480	/// \param VD The variable whose initializer should be obtained.
3481	/// \param Version The version of the variable within the frame.
3482	/// \param Frame The frame in which the variable was created. Must be null
3483	/// if this variable is not local to the evaluation.
3484	/// \param Result Filled in with a pointer to the value of the variable.
3485	static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
3486	const VarDecl *VD, CallStackFrame *Frame,
3487	unsigned Version, APValue *&Result) {
3488	// C++23 [expr.const]p8 If we have a reference type allow unknown references
3489	// and pointers.
3490	bool AllowConstexprUnknown =
3491	Info.getLangOpts().CPlusPlus23 && VD->getType()->isReferenceType();
3492
3493	APValue::LValueBase Base(VD, Frame ? Frame->Index : 0, Version);
3494
3495	auto CheckUninitReference = [&](bool IsLocalVariable) {
3496	if (!Result->hasValue() && VD->getType()->isReferenceType()) {
3497	// C++23 [expr.const]p8
3498	// ... For such an object that is not usable in constant expressions, the
3499	// dynamic type of the object is constexpr-unknown. For such a reference
3500	// that is not usable in constant expressions, the reference is treated
3501	// as binding to an unspecified object of the referenced type whose
3502	// lifetime and that of all subobjects includes the entire constant
3503	// evaluation and whose dynamic type is constexpr-unknown.
3504	//
3505	// Variables that are part of the current evaluation are not
3506	// constexpr-unknown.
3507	if (!AllowConstexprUnknown || IsLocalVariable) {
3508	if (!Info.checkingPotentialConstantExpression())
3509	Info.FFDiag(E, diag::note_constexpr_use_uninit_reference);
3510	return false;
3511	}
3512	Result = &Info.CurrentCall->createConstexprUnknownAPValues(Key: VD, Base);
3513	}
3514	return true;
3515	};
3516
3517	// If this is a local variable, dig out its value.
3518	if (Frame) {
3519	Result = Frame->getTemporary(Key: VD, Version);
3520	if (Result)
3521	return CheckUninitReference(/*IsLocalVariable=*/true);
3522
3523	if (!isa<ParmVarDecl>(Val: VD)) {
3524	// Assume variables referenced within a lambda's call operator that were
3525	// not declared within the call operator are captures and during checking
3526	// of a potential constant expression, assume they are unknown constant
3527	// expressions.
3528	assert(isLambdaCallOperator(Frame->Callee) &&
3529	(VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&
3530	"missing value for local variable");
3531	if (Info.checkingPotentialConstantExpression())
3532	return false;
3533	// FIXME: This diagnostic is bogus; we do support captures. Is this code
3534	// still reachable at all?
3535	Info.FFDiag(E->getBeginLoc(),
3536	diag::note_unimplemented_constexpr_lambda_feature_ast)
3537	<< "captures not currently allowed";
3538	return false;
3539	}
3540	}
3541
3542	// If we're currently evaluating the initializer of this declaration, use that
3543	// in-flight value.
3544	if (Info.EvaluatingDecl == Base) {
3545	Result = Info.EvaluatingDeclValue;
3546	return CheckUninitReference(/*IsLocalVariable=*/false);
3547	}
3548
3549	// P2280R4 struck the restriction that variable of reference type lifetime
3550	// should begin within the evaluation of E
3551	// Used to be C++20 [expr.const]p5.12.2:
3552	// ... its lifetime began within the evaluation of E;
3553	if (isa<ParmVarDecl>(Val: VD)) {
3554	if (AllowConstexprUnknown) {
3555	Result = &Info.CurrentCall->createConstexprUnknownAPValues(Key: VD, Base);
3556	return true;
3557	}
3558
3559	// Assume parameters of a potential constant expression are usable in
3560	// constant expressions.
3561	if (!Info.checkingPotentialConstantExpression() ||
3562	!Info.CurrentCall->Callee ||
3563	!Info.CurrentCall->Callee->Equals(DC: VD->getDeclContext())) {
3564	if (Info.getLangOpts().CPlusPlus11) {
3565	Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown)
3566	<< VD;
3567	NoteLValueLocation(Info, Base);
3568	} else {
3569	Info.FFDiag(E);
3570	}
3571	}
3572	return false;
3573	}
3574
3575	if (E->isValueDependent())
3576	return false;
3577
3578	// Dig out the initializer, and use the declaration which it's attached to.
3579	// FIXME: We should eventually check whether the variable has a reachable
3580	// initializing declaration.
3581	const Expr *Init = VD->getAnyInitializer(D&: VD);
3582	// P2280R4 struck the restriction that variable of reference type should have
3583	// a preceding initialization.
3584	// Used to be C++20 [expr.const]p5.12:
3585	// ... reference has a preceding initialization and either ...
3586	if (!Init && !AllowConstexprUnknown) {
3587	// Don't diagnose during potential constant expression checking; an
3588	// initializer might be added later.
3589	if (!Info.checkingPotentialConstantExpression()) {
3590	Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1)
3591	<< VD;
3592	NoteLValueLocation(Info, Base);
3593	}
3594	return false;
3595	}
3596
3597	// P2280R4 struck the initialization requirement for variables of reference
3598	// type so we can no longer assume we have an Init.
3599	// Used to be C++20 [expr.const]p5.12:
3600	// ... reference has a preceding initialization and either ...
3601	if (Init && Init->isValueDependent()) {
3602	// The DeclRefExpr is not value-dependent, but the variable it refers to
3603	// has a value-dependent initializer. This should only happen in
3604	// constant-folding cases, where the variable is not actually of a suitable
3605	// type for use in a constant expression (otherwise the DeclRefExpr would
3606	// have been value-dependent too), so diagnose that.
3607	assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx));
3608	if (!Info.checkingPotentialConstantExpression()) {
3609	Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
3610	? diag::note_constexpr_ltor_non_constexpr
3611	: diag::note_constexpr_ltor_non_integral, 1)
3612	<< VD << VD->getType();
3613	NoteLValueLocation(Info, Base);
3614	}
3615	return false;
3616	}
3617
3618	// Check that we can fold the initializer. In C++, we will have already done
3619	// this in the cases where it matters for conformance.
3620	// P2280R4 struck the initialization requirement for variables of reference
3621	// type so we can no longer assume we have an Init.
3622	// Used to be C++20 [expr.const]p5.12:
3623	// ... reference has a preceding initialization and either ...
3624	if (Init && !VD->evaluateValue() && !AllowConstexprUnknown) {
3625	Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3626	NoteLValueLocation(Info, Base);
3627	return false;
3628	}
3629
3630	// Check that the variable is actually usable in constant expressions. For a
3631	// const integral variable or a reference, we might have a non-constant
3632	// initializer that we can nonetheless evaluate the initializer for. Such
3633	// variables are not usable in constant expressions. In C++98, the
3634	// initializer also syntactically needs to be an ICE.
3635	//
3636	// FIXME: We don't diagnose cases that aren't potentially usable in constant
3637	// expressions here; doing so would regress diagnostics for things like
3638	// reading from a volatile constexpr variable.
3639	if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization() &&
3640	VD->mightBeUsableInConstantExpressions(C: Info.Ctx) &&
3641	!AllowConstexprUnknown) ||
3642	((Info.getLangOpts().CPlusPlus || Info.getLangOpts().OpenCL) &&
3643	!Info.getLangOpts().CPlusPlus11 && !VD->hasICEInitializer(Context: Info.Ctx))) {
3644	if (Init) {
3645	Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
3646	NoteLValueLocation(Info, Base);
3647	} else {
3648	Info.CCEDiag(E);
3649	}
3650	}
3651
3652	// Never use the initializer of a weak variable, not even for constant
3653	// folding. We can't be sure that this is the definition that will be used.
3654	if (VD->isWeak()) {
3655	Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD;
3656	NoteLValueLocation(Info, Base);
3657	return false;
3658	}
3659
3660	Result = VD->getEvaluatedValue();
3661
3662	if (!Result) {
3663	if (AllowConstexprUnknown)
3664	Result = &Info.CurrentCall->createConstexprUnknownAPValues(Key: VD, Base);
3665	else
3666	return false;
3667	}
3668
3669	return CheckUninitReference(/*IsLocalVariable=*/false);
3670	}
3671
3672	/// Get the base index of the given base class within an APValue representing
3673	/// the given derived class.
3674	static unsigned getBaseIndex(const CXXRecordDecl *Derived,
3675	const CXXRecordDecl *Base) {
3676	Base = Base->getCanonicalDecl();
3677	unsigned Index = 0;
3678	for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
3679	E = Derived->bases_end(); I != E; ++I, ++Index) {
3680	if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
3681	return Index;
3682	}
3683
3684	llvm_unreachable("base class missing from derived class's bases list");
3685	}
3686
3687	/// Extract the value of a character from a string literal.
3688	static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
3689	uint64_t Index) {
3690	assert(!isa<SourceLocExpr>(Lit) &&
3691	"SourceLocExpr should have already been converted to a StringLiteral");
3692
3693	// FIXME: Support MakeStringConstant
3694	if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Val: Lit)) {
3695	std::string Str;
3696	Info.Ctx.getObjCEncodingForType(T: ObjCEnc->getEncodedType(), S&: Str);
3697	assert(Index <= Str.size() && "Index too large");
3698	return APSInt::getUnsigned(X: Str.c_str()[Index]);
3699	}
3700
3701	if (auto PE = dyn_cast<PredefinedExpr>(Val: Lit))
3702	Lit = PE->getFunctionName();
3703	const StringLiteral *S = cast<StringLiteral>(Val: Lit);
3704	const ConstantArrayType *CAT =
3705	Info.Ctx.getAsConstantArrayType(T: S->getType());
3706	assert(CAT && "string literal isn't an array");
3707	QualType CharType = CAT->getElementType();
3708	assert(CharType->isIntegerType() && "unexpected character type");
3709	APSInt Value(Info.Ctx.getTypeSize(T: CharType),
3710	CharType->isUnsignedIntegerType());
3711	if (Index < S->getLength())
3712	Value = S->getCodeUnit(i: Index);
3713	return Value;
3714	}
3715
3716	// Expand a string literal into an array of characters.
3717	//
3718	// FIXME: This is inefficient; we should probably introduce something similar
3719	// to the LLVM ConstantDataArray to make this cheaper.
3720	static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
3721	APValue &Result,
3722	QualType AllocType = QualType()) {
3723	const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
3724	T: AllocType.isNull() ? S->getType() : AllocType);
3725	assert(CAT && "string literal isn't an array");
3726	QualType CharType = CAT->getElementType();
3727	assert(CharType->isIntegerType() && "unexpected character type");
3728
3729	unsigned Elts = CAT->getZExtSize();
3730	Result = APValue(APValue::UninitArray(),
3731	std::min(a: S->getLength(), b: Elts), Elts);
3732	APSInt Value(Info.Ctx.getTypeSize(T: CharType),
3733	CharType->isUnsignedIntegerType());
3734	if (Result.hasArrayFiller())
3735	Result.getArrayFiller() = APValue(Value);
3736	for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
3737	Value = S->getCodeUnit(i: I);
3738	Result.getArrayInitializedElt(I) = APValue(Value);
3739	}
3740	}
3741
3742	// Expand an array so that it has more than Index filled elements.
3743	static void expandArray(APValue &Array, unsigned Index) {
3744	unsigned Size = Array.getArraySize();
3745	assert(Index < Size);
3746
3747	// Always at least double the number of elements for which we store a value.
3748	unsigned OldElts = Array.getArrayInitializedElts();
3749	unsigned NewElts = std::max(a: Index+1, b: OldElts * 2);
3750	NewElts = std::min(a: Size, b: std::max(a: NewElts, b: 8u));
3751
3752	// Copy the data across.
3753	APValue NewValue(APValue::UninitArray(), NewElts, Size);
3754	for (unsigned I = 0; I != OldElts; ++I)
3755	NewValue.getArrayInitializedElt(I).swap(RHS&: Array.getArrayInitializedElt(I));
3756	for (unsigned I = OldElts; I != NewElts; ++I)
3757	NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
3758	if (NewValue.hasArrayFiller())
3759	NewValue.getArrayFiller() = Array.getArrayFiller();
3760	Array.swap(RHS&: NewValue);
3761	}
3762
3763	/// Determine whether a type would actually be read by an lvalue-to-rvalue
3764	/// conversion. If it's of class type, we may assume that the copy operation
3765	/// is trivial. Note that this is never true for a union type with fields
3766	/// (because the copy always "reads" the active member) and always true for
3767	/// a non-class type.
3768	static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD);
3769	static bool isReadByLvalueToRvalueConversion(QualType T) {
3770	CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3771	return !RD || isReadByLvalueToRvalueConversion(RD);
3772	}
3773	static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD) {
3774	// FIXME: A trivial copy of a union copies the object representation, even if
3775	// the union is empty.
3776	if (RD->isUnion())
3777	return !RD->field_empty();
3778	if (RD->isEmpty())
3779	return false;
3780
3781	for (auto *Field : RD->fields())
3782	if (!Field->isUnnamedBitField() &&
3783	isReadByLvalueToRvalueConversion(Field->getType()))
3784	return true;
3785
3786	for (auto &BaseSpec : RD->bases())
3787	if (isReadByLvalueToRvalueConversion(T: BaseSpec.getType()))
3788	return true;
3789
3790	return false;
3791	}
3792
3793	/// Diagnose an attempt to read from any unreadable field within the specified
3794	/// type, which might be a class type.
3795	static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
3796	QualType T) {
3797	CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
3798	if (!RD)
3799	return false;
3800
3801	if (!RD->hasMutableFields())
3802	return false;
3803
3804	for (auto *Field : RD->fields()) {
3805	// If we're actually going to read this field in some way, then it can't
3806	// be mutable. If we're in a union, then assigning to a mutable field
3807	// (even an empty one) can change the active member, so that's not OK.
3808	// FIXME: Add core issue number for the union case.
3809	if (Field->isMutable() &&
3810	(RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
3811	Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
3812	Info.Note(Field->getLocation(), diag::note_declared_at);
3813	return true;
3814	}
3815
3816	if (diagnoseMutableFields(Info, E, AK, Field->getType()))
3817	return true;
3818	}
3819
3820	for (auto &BaseSpec : RD->bases())
3821	if (diagnoseMutableFields(Info, E, AK, T: BaseSpec.getType()))
3822	return true;
3823
3824	// All mutable fields were empty, and thus not actually read.
3825	return false;
3826	}
3827
3828	static bool lifetimeStartedInEvaluation(EvalInfo &Info,
3829	APValue::LValueBase Base,
3830	bool MutableSubobject = false) {
3831	// A temporary or transient heap allocation we created.
3832	if (Base.getCallIndex() || Base.is<DynamicAllocLValue>())
3833	return true;
3834
3835	switch (Info.IsEvaluatingDecl) {
3836	case EvalInfo::EvaluatingDeclKind::None:
3837	return false;
3838
3839	case EvalInfo::EvaluatingDeclKind::Ctor:
3840	// The variable whose initializer we're evaluating.
3841	if (Info.EvaluatingDecl == Base)
3842	return true;
3843
3844	// A temporary lifetime-extended by the variable whose initializer we're
3845	// evaluating.
3846	if (auto *BaseE = Base.dyn_cast<const Expr *>())
3847	if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(Val: BaseE))
3848	return Info.EvaluatingDecl == BaseMTE->getExtendingDecl();
3849	return false;
3850
3851	case EvalInfo::EvaluatingDeclKind::Dtor:
3852	// C++2a [expr.const]p6:
3853	// [during constant destruction] the lifetime of a and its non-mutable
3854	// subobjects (but not its mutable subobjects) [are] considered to start
3855	// within e.
3856	if (MutableSubobject || Base != Info.EvaluatingDecl)
3857	return false;
3858	// FIXME: We can meaningfully extend this to cover non-const objects, but
3859	// we will need special handling: we should be able to access only
3860	// subobjects of such objects that are themselves declared const.
3861	QualType T = getType(B: Base);
3862	return T.isConstQualified() || T->isReferenceType();
3863	}
3864
3865	llvm_unreachable("unknown evaluating decl kind");
3866	}
3867
3868	static bool CheckArraySize(EvalInfo &Info, const ConstantArrayType *CAT,
3869	SourceLocation CallLoc = {}) {
3870	return Info.CheckArraySize(
3871	Loc: CAT->getSizeExpr() ? CAT->getSizeExpr()->getBeginLoc() : CallLoc,
3872	BitWidth: CAT->getNumAddressingBits(Context: Info.Ctx), ElemCount: CAT->getZExtSize(),
3873	/*Diag=*/true);
3874	}
3875
3876	namespace {
3877	/// A handle to a complete object (an object that is not a subobject of
3878	/// another object).
3879	struct CompleteObject {
3880	/// The identity of the object.
3881	APValue::LValueBase Base;
3882	/// The value of the complete object.
3883	APValue *Value;
3884	/// The type of the complete object.
3885	QualType Type;
3886
3887	CompleteObject() : Value(nullptr) {}
3888	CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type)
3889	: Base(Base), Value(Value), Type(Type) {}
3890
3891	bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
3892	// If this isn't a "real" access (eg, if it's just accessing the type
3893	// info), allow it. We assume the type doesn't change dynamically for
3894	// subobjects of constexpr objects (even though we'd hit UB here if it
3895	// did). FIXME: Is this right?
3896	if (!isAnyAccess(AK))
3897	return true;
3898
3899	// In C++14 onwards, it is permitted to read a mutable member whose
3900	// lifetime began within the evaluation.
3901	// FIXME: Should we also allow this in C++11?
3902	if (!Info.getLangOpts().CPlusPlus14 &&
3903	AK != AccessKinds::AK_IsWithinLifetime)
3904	return false;
3905	return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
3906	}
3907
3908	explicit operator bool() const { return !Type.isNull(); }
3909	};
3910	} // end anonymous namespace
3911
3912	static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
3913	bool IsMutable = false) {
3914	// C++ [basic.type.qualifier]p1:
3915	// - A const object is an object of type const T or a non-mutable subobject
3916	// of a const object.
3917	if (ObjType.isConstQualified() && !IsMutable)
3918	SubobjType.addConst();
3919	// - A volatile object is an object of type const T or a subobject of a
3920	// volatile object.
3921	if (ObjType.isVolatileQualified())
3922	SubobjType.addVolatile();
3923	return SubobjType;
3924	}
3925
3926	/// Find the designated sub-object of an rvalue.
3927	template <typename SubobjectHandler>
3928	static typename SubobjectHandler::result_type
3929	findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
3930	const SubobjectDesignator &Sub, SubobjectHandler &handler) {
3931	if (Sub.Invalid)
3932	// A diagnostic will have already been produced.
3933	return handler.failed();
3934	if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
3935	if (Info.getLangOpts().CPlusPlus11)
3936	Info.FFDiag(E, Sub.isOnePastTheEnd()
3937	? diag::note_constexpr_access_past_end
3938	: diag::note_constexpr_access_unsized_array)
3939	<< handler.AccessKind;
3940	else
3941	Info.FFDiag(E);
3942	return handler.failed();
3943	}
3944
3945	APValue *O = Obj.Value;
3946	QualType ObjType = Obj.Type;
3947	const FieldDecl *LastField = nullptr;
3948	const FieldDecl *VolatileField = nullptr;
3949
3950	// C++23 [expr.const]p8 If we have an unknown reference or pointers and it
3951	// does not have a value then bail out.
3952	if (O->allowConstexprUnknown() && !O->hasValue())
3953	return false;
3954
3955	// Walk the designator's path to find the subobject.
3956	for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
3957	// Reading an indeterminate value is undefined, but assigning over one is OK.
3958	if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) ||
3959	(O->isIndeterminate() &&
3960	!isValidIndeterminateAccess(handler.AccessKind))) {
3961	// Object has ended lifetime.
3962	// If I is non-zero, some subobject (member or array element) of a
3963	// complete object has ended its lifetime, so this is valid for
3964	// IsWithinLifetime, resulting in false.
3965	if (I != 0 && handler.AccessKind == AK_IsWithinLifetime)
3966	return false;
3967	if (!Info.checkingPotentialConstantExpression())
3968	Info.FFDiag(E, diag::note_constexpr_access_uninit)
3969	<< handler.AccessKind << O->isIndeterminate()
3970	<< E->getSourceRange();
3971	return handler.failed();
3972	}
3973
3974	// C++ [class.ctor]p5, C++ [class.dtor]p5:
3975	// const and volatile semantics are not applied on an object under
3976	// {con,de}struction.
3977	if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) &&
3978	ObjType->isRecordType() &&
3979	Info.isEvaluatingCtorDtor(
3980	Base: Obj.Base,
3981	Path: llvm::ArrayRef(Sub.Entries.begin(), Sub.Entries.begin() + I)) !=
3982	ConstructionPhase::None) {
3983	ObjType = Info.Ctx.getCanonicalType(T: ObjType);
3984	ObjType.removeLocalConst();
3985	ObjType.removeLocalVolatile();
3986	}
3987
3988	// If this is our last pass, check that the final object type is OK.
3989	if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) {
3990	// Accesses to volatile objects are prohibited.
3991	if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) {
3992	if (Info.getLangOpts().CPlusPlus) {
3993	int DiagKind;
3994	SourceLocation Loc;
3995	const NamedDecl *Decl = nullptr;
3996	if (VolatileField) {
3997	DiagKind = 2;
3998	Loc = VolatileField->getLocation();
3999	Decl = VolatileField;
4000	} else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
4001	DiagKind = 1;
4002	Loc = VD->getLocation();
4003	Decl = VD;
4004	} else {
4005	DiagKind = 0;
4006	if (auto *E = Obj.Base.dyn_cast<const Expr *>())
4007	Loc = E->getExprLoc();
4008	}
4009	Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
4010	<< handler.AccessKind << DiagKind << Decl;
4011	Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
4012	} else {
4013	Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
4014	}
4015	return handler.failed();
4016	}
4017
4018	// If we are reading an object of class type, there may still be more
4019	// things we need to check: if there are any mutable subobjects, we
4020	// cannot perform this read. (This only happens when performing a trivial
4021	// copy or assignment.)
4022	if (ObjType->isRecordType() &&
4023	!Obj.mayAccessMutableMembers(Info, AK: handler.AccessKind) &&
4024	diagnoseMutableFields(Info, E, handler.AccessKind, ObjType))
4025	return handler.failed();
4026	}
4027
4028	if (I == N) {
4029	if (!handler.found(*O, ObjType))
4030	return false;
4031
4032	// If we modified a bit-field, truncate it to the right width.
4033	if (isModification(handler.AccessKind) &&
4034	LastField && LastField->isBitField() &&
4035	!truncateBitfieldValue(Info, E, Value&: *O, FD: LastField))
4036	return false;
4037
4038	return true;
4039	}
4040
4041	LastField = nullptr;
4042	if (ObjType->isArrayType()) {
4043	// Next subobject is an array element.
4044	const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T: ObjType);
4045	assert(CAT && "vla in literal type?");
4046	uint64_t Index = Sub.Entries[I].getAsArrayIndex();
4047	if (CAT->getSize().ule(RHS: Index)) {
4048	// Note, it should not be possible to form a pointer with a valid
4049	// designator which points more than one past the end of the array.
4050	if (Info.getLangOpts().CPlusPlus11)
4051	Info.FFDiag(E, diag::note_constexpr_access_past_end)
4052	<< handler.AccessKind;
4053	else
4054	Info.FFDiag(E);
4055	return handler.failed();
4056	}
4057
4058	ObjType = CAT->getElementType();
4059
4060	if (O->getArrayInitializedElts() > Index)
4061	O = &O->getArrayInitializedElt(I: Index);
4062	else if (!isRead(handler.AccessKind)) {
4063	if (!CheckArraySize(Info, CAT, CallLoc: E->getExprLoc()))
4064	return handler.failed();
4065
4066	expandArray(Array&: *O, Index);
4067	O = &O->getArrayInitializedElt(I: Index);
4068	} else
4069	O = &O->getArrayFiller();
4070	} else if (ObjType->isAnyComplexType()) {
4071	// Next subobject is a complex number.
4072	uint64_t Index = Sub.Entries[I].getAsArrayIndex();
4073	if (Index > 1) {
4074	if (Info.getLangOpts().CPlusPlus11)
4075	Info.FFDiag(E, diag::note_constexpr_access_past_end)
4076	<< handler.AccessKind;
4077	else
4078	Info.FFDiag(E);
4079	return handler.failed();
4080	}
4081
4082	ObjType = getSubobjectType(
4083	ObjType, SubobjType: ObjType->castAs<ComplexType>()->getElementType());
4084
4085	assert(I == N - 1 && "extracting subobject of scalar?");
4086	if (O->isComplexInt()) {
4087	return handler.found(Index ? O->getComplexIntImag()
4088	: O->getComplexIntReal(), ObjType);
4089	} else {
4090	assert(O->isComplexFloat());
4091	return handler.found(Index ? O->getComplexFloatImag()
4092	: O->getComplexFloatReal(), ObjType);
4093	}
4094	} else if (const auto *VT = ObjType->getAs<VectorType>()) {
4095	uint64_t Index = Sub.Entries[I].getAsArrayIndex();
4096	unsigned NumElements = VT->getNumElements();
4097	if (Index == NumElements) {
4098	if (Info.getLangOpts().CPlusPlus11)
4099	Info.FFDiag(E, diag::note_constexpr_access_past_end)
4100	<< handler.AccessKind;
4101	else
4102	Info.FFDiag(E);
4103	return handler.failed();
4104	}
4105
4106	if (Index > NumElements) {
4107	Info.CCEDiag(E, diag::note_constexpr_array_index)
4108	<< Index << /*array*/ 0 << NumElements;
4109	return handler.failed();
4110	}
4111
4112	ObjType = VT->getElementType();
4113	assert(I == N - 1 && "extracting subobject of scalar?");
4114	return handler.found(O->getVectorElt(I: Index), ObjType);
4115	} else if (const FieldDecl *Field = getAsField(E: Sub.Entries[I])) {
4116	if (Field->isMutable() &&
4117	!Obj.mayAccessMutableMembers(Info, AK: handler.AccessKind)) {
4118	Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
4119	<< handler.AccessKind << Field;
4120	Info.Note(Field->getLocation(), diag::note_declared_at);
4121	return handler.failed();
4122	}
4123
4124	// Next subobject is a class, struct or union field.
4125	RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
4126	if (RD->isUnion()) {
4127	const FieldDecl *UnionField = O->getUnionField();
4128	if (!UnionField ||
4129	UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
4130	if (I == N - 1 && handler.AccessKind == AK_Construct) {
4131	// Placement new onto an inactive union member makes it active.
4132	O->setUnion(Field, Value: APValue());
4133	} else {
4134	// Pointer to/into inactive union member: Not within lifetime
4135	if (handler.AccessKind == AK_IsWithinLifetime)
4136	return false;
4137	// FIXME: If O->getUnionValue() is absent, report that there's no
4138	// active union member rather than reporting the prior active union
4139	// member. We'll need to fix nullptr_t to not use APValue() as its
4140	// representation first.
4141	Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
4142	<< handler.AccessKind << Field << !UnionField << UnionField;
4143	return handler.failed();
4144	}
4145	}
4146	O = &O->getUnionValue();
4147	} else
4148	O = &O->getStructField(i: Field->getFieldIndex());
4149
4150	ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
4151	LastField = Field;
4152	if (Field->getType().isVolatileQualified())
4153	VolatileField = Field;
4154	} else {
4155	// Next subobject is a base class.
4156	const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
4157	const CXXRecordDecl *Base = getAsBaseClass(E: Sub.Entries[I]);
4158	O = &O->getStructBase(i: getBaseIndex(Derived, Base));
4159
4160	ObjType = getSubobjectType(ObjType, SubobjType: Info.Ctx.getRecordType(Base));
4161	}
4162	}
4163	}
4164
4165	namespace {
4166	struct ExtractSubobjectHandler {
4167	EvalInfo &Info;
4168	const Expr *E;
4169	APValue &Result;
4170	const AccessKinds AccessKind;
4171
4172	typedef bool result_type;
4173	bool failed() { return false; }
4174	bool found(APValue &Subobj, QualType SubobjType) {
4175	Result = Subobj;
4176	if (AccessKind == AK_ReadObjectRepresentation)
4177	return true;
4178	return CheckFullyInitialized(Info, DiagLoc: E->getExprLoc(), Type: SubobjType, Value: Result);
4179	}
4180	bool found(APSInt &Value, QualType SubobjType) {
4181	Result = APValue(Value);
4182	return true;
4183	}
4184	bool found(APFloat &Value, QualType SubobjType) {
4185	Result = APValue(Value);
4186	return true;
4187	}
4188	};
4189	} // end anonymous namespace
4190
4191	/// Extract the designated sub-object of an rvalue.
4192	static bool extractSubobject(EvalInfo &Info, const Expr *E,
4193	const CompleteObject &Obj,
4194	const SubobjectDesignator &Sub, APValue &Result,
4195	AccessKinds AK = AK_Read) {
4196	assert(AK == AK_Read || AK == AK_ReadObjectRepresentation);
4197	ExtractSubobjectHandler Handler = {.Info: Info, .E: E, .Result: Result, .AccessKind: AK};
4198	return findSubobject(Info, E, Obj, Sub, handler&: Handler);
4199	}
4200
4201	namespace {
4202	struct ModifySubobjectHandler {
4203	EvalInfo &Info;
4204	APValue &NewVal;
4205	const Expr *E;
4206
4207	typedef bool result_type;
4208	static const AccessKinds AccessKind = AK_Assign;
4209
4210	bool checkConst(QualType QT) {
4211	// Assigning to a const object has undefined behavior.
4212	if (QT.isConstQualified()) {
4213	Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4214	return false;
4215	}
4216	return true;
4217	}
4218
4219	bool failed() { return false; }
4220	bool found(APValue &Subobj, QualType SubobjType) {
4221	if (!checkConst(QT: SubobjType))
4222	return false;
4223	// We've been given ownership of NewVal, so just swap it in.
4224	Subobj.swap(RHS&: NewVal);
4225	return true;
4226	}
4227	bool found(APSInt &Value, QualType SubobjType) {
4228	if (!checkConst(QT: SubobjType))
4229	return false;
4230	if (!NewVal.isInt()) {
4231	// Maybe trying to write a cast pointer value into a complex?
4232	Info.FFDiag(E);
4233	return false;
4234	}
4235	Value = NewVal.getInt();
4236	return true;
4237	}
4238	bool found(APFloat &Value, QualType SubobjType) {
4239	if (!checkConst(QT: SubobjType))
4240	return false;
4241	Value = NewVal.getFloat();
4242	return true;
4243	}
4244	};
4245	} // end anonymous namespace
4246
4247	const AccessKinds ModifySubobjectHandler::AccessKind;
4248
4249	/// Update the designated sub-object of an rvalue to the given value.
4250	static bool modifySubobject(EvalInfo &Info, const Expr *E,
4251	const CompleteObject &Obj,
4252	const SubobjectDesignator &Sub,
4253	APValue &NewVal) {
4254	ModifySubobjectHandler Handler = { .Info: Info, .NewVal: NewVal, .E: E };
4255	return findSubobject(Info, E, Obj, Sub, handler&: Handler);
4256	}
4257
4258	/// Find the position where two subobject designators diverge, or equivalently
4259	/// the length of the common initial subsequence.
4260	static unsigned FindDesignatorMismatch(QualType ObjType,
4261	const SubobjectDesignator &A,
4262	const SubobjectDesignator &B,
4263	bool &WasArrayIndex) {
4264	unsigned I = 0, N = std::min(a: A.Entries.size(), b: B.Entries.size());
4265	for (/**/; I != N; ++I) {
4266	if (!ObjType.isNull() &&
4267	(ObjType->isArrayType() || ObjType->isAnyComplexType())) {
4268	// Next subobject is an array element.
4269	if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) {
4270	WasArrayIndex = true;
4271	return I;
4272	}
4273	if (ObjType->isAnyComplexType())
4274	ObjType = ObjType->castAs<ComplexType>()->getElementType();
4275	else
4276	ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
4277	} else {
4278	if (A.Entries[I].getAsBaseOrMember() !=
4279	B.Entries[I].getAsBaseOrMember()) {
4280	WasArrayIndex = false;
4281	return I;
4282	}
4283	if (const FieldDecl *FD = getAsField(E: A.Entries[I]))
4284	// Next subobject is a field.
4285	ObjType = FD->getType();
4286	else
4287	// Next subobject is a base class.
4288	ObjType = QualType();
4289	}
4290	}
4291	WasArrayIndex = false;
4292	return I;
4293	}
4294
4295	/// Determine whether the given subobject designators refer to elements of the
4296	/// same array object.
4297	static bool AreElementsOfSameArray(QualType ObjType,
4298	const SubobjectDesignator &A,
4299	const SubobjectDesignator &B) {
4300	if (A.Entries.size() != B.Entries.size())
4301	return false;
4302
4303	bool IsArray = A.MostDerivedIsArrayElement;
4304	if (IsArray && A.MostDerivedPathLength != A.Entries.size())
4305	// A is a subobject of the array element.
4306	return false;
4307
4308	// If A (and B) designates an array element, the last entry will be the array
4309	// index. That doesn't have to match. Otherwise, we're in the 'implicit array
4310	// of length 1' case, and the entire path must match.
4311	bool WasArrayIndex;
4312	unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
4313	return CommonLength >= A.Entries.size() - IsArray;
4314	}
4315
4316	/// Find the complete object to which an LValue refers.
4317	static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
4318	AccessKinds AK, const LValue &LVal,
4319	QualType LValType) {
4320	if (LVal.InvalidBase) {
4321	Info.FFDiag(E);
4322	return CompleteObject();
4323	}
4324
4325	if (!LVal.Base) {
4326	Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
4327	return CompleteObject();
4328	}
4329
4330	CallStackFrame *Frame = nullptr;
4331	unsigned Depth = 0;
4332	if (LVal.getLValueCallIndex()) {
4333	std::tie(args&: Frame, args&: Depth) =
4334	Info.getCallFrameAndDepth(CallIndex: LVal.getLValueCallIndex());
4335	if (!Frame) {
4336	Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
4337	<< AK << LVal.Base.is<const ValueDecl*>();
4338	NoteLValueLocation(Info, Base: LVal.Base);
4339	return CompleteObject();
4340	}
4341	}
4342
4343	bool IsAccess = isAnyAccess(AK);
4344
4345	// C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
4346	// is not a constant expression (even if the object is non-volatile). We also
4347	// apply this rule to C++98, in order to conform to the expected 'volatile'
4348	// semantics.
4349	if (isFormalAccess(AK) && LValType.isVolatileQualified()) {
4350	if (Info.getLangOpts().CPlusPlus)
4351	Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
4352	<< AK << LValType;
4353	else
4354	Info.FFDiag(E);
4355	return CompleteObject();
4356	}
4357
4358	// Compute value storage location and type of base object.
4359	APValue *BaseVal = nullptr;
4360	QualType BaseType = getType(B: LVal.Base);
4361
4362	if (Info.getLangOpts().CPlusPlus14 && LVal.Base == Info.EvaluatingDecl &&
4363	lifetimeStartedInEvaluation(Info, Base: LVal.Base)) {
4364	// This is the object whose initializer we're evaluating, so its lifetime
4365	// started in the current evaluation.
4366	BaseVal = Info.EvaluatingDeclValue;
4367	} else if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl *>()) {
4368	// Allow reading from a GUID declaration.
4369	if (auto *GD = dyn_cast<MSGuidDecl>(Val: D)) {
4370	if (isModification(AK)) {
4371	// All the remaining cases do not permit modification of the object.
4372	Info.FFDiag(E, diag::note_constexpr_modify_global);
4373	return CompleteObject();
4374	}
4375	APValue &V = GD->getAsAPValue();
4376	if (V.isAbsent()) {
4377	Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
4378	<< GD->getType();
4379	return CompleteObject();
4380	}
4381	return CompleteObject(LVal.Base, &V, GD->getType());
4382	}
4383
4384	// Allow reading the APValue from an UnnamedGlobalConstantDecl.
4385	if (auto *GCD = dyn_cast<UnnamedGlobalConstantDecl>(Val: D)) {
4386	if (isModification(AK)) {
4387	Info.FFDiag(E, diag::note_constexpr_modify_global);
4388	return CompleteObject();
4389	}
4390	return CompleteObject(LVal.Base, const_cast<APValue *>(&GCD->getValue()),
4391	GCD->getType());
4392	}
4393
4394	// Allow reading from template parameter objects.
4395	if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(Val: D)) {
4396	if (isModification(AK)) {
4397	Info.FFDiag(E, diag::note_constexpr_modify_global);
4398	return CompleteObject();
4399	}
4400	return CompleteObject(LVal.Base, const_cast<APValue *>(&TPO->getValue()),
4401	TPO->getType());
4402	}
4403
4404	// In C++98, const, non-volatile integers initialized with ICEs are ICEs.
4405	// In C++11, constexpr, non-volatile variables initialized with constant
4406	// expressions are constant expressions too. Inside constexpr functions,
4407	// parameters are constant expressions even if they're non-const.
4408	// In C++1y, objects local to a constant expression (those with a Frame) are
4409	// both readable and writable inside constant expressions.
4410	// In C, such things can also be folded, although they are not ICEs.
4411	const VarDecl *VD = dyn_cast<VarDecl>(Val: D);
4412	if (VD) {
4413	if (const VarDecl *VDef = VD->getDefinition(C&: Info.Ctx))
4414	VD = VDef;
4415	}
4416	if (!VD || VD->isInvalidDecl()) {
4417	Info.FFDiag(E);
4418	return CompleteObject();
4419	}
4420
4421	bool IsConstant = BaseType.isConstant(Ctx: Info.Ctx);
4422	bool ConstexprVar = false;
4423	if (const auto *VD = dyn_cast_if_present<VarDecl>(
4424	Val: Info.EvaluatingDecl.dyn_cast<const ValueDecl *>()))
4425	ConstexprVar = VD->isConstexpr();
4426
4427	// Unless we're looking at a local variable or argument in a constexpr call,
4428	// the variable we're reading must be const.
4429	if (!Frame) {
4430	if (IsAccess && isa<ParmVarDecl>(Val: VD)) {
4431	// Access of a parameter that's not associated with a frame isn't going
4432	// to work out, but we can leave it to evaluateVarDeclInit to provide a
4433	// suitable diagnostic.
4434	} else if (Info.getLangOpts().CPlusPlus14 &&
4435	lifetimeStartedInEvaluation(Info, Base: LVal.Base)) {
4436	// OK, we can read and modify an object if we're in the process of
4437	// evaluating its initializer, because its lifetime began in this
4438	// evaluation.
4439	} else if (isModification(AK)) {
4440	// All the remaining cases do not permit modification of the object.
4441	Info.FFDiag(E, diag::note_constexpr_modify_global);
4442	return CompleteObject();
4443	} else if (VD->isConstexpr()) {
4444	// OK, we can read this variable.
4445	} else if (Info.getLangOpts().C23 && ConstexprVar) {
4446	Info.FFDiag(E);
4447	return CompleteObject();
4448	} else if (BaseType->isIntegralOrEnumerationType()) {
4449	if (!IsConstant) {
4450	if (!IsAccess)
4451	return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4452	if (Info.getLangOpts().CPlusPlus) {
4453	Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
4454	Info.Note(VD->getLocation(), diag::note_declared_at);
4455	} else {
4456	Info.FFDiag(E);
4457	}
4458	return CompleteObject();
4459	}
4460	} else if (!IsAccess) {
4461	return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4462	} else if (IsConstant && Info.checkingPotentialConstantExpression() &&
4463	BaseType->isLiteralType(Ctx: Info.Ctx) && !VD->hasDefinition()) {
4464	// This variable might end up being constexpr. Don't diagnose it yet.
4465	} else if (IsConstant) {
4466	// Keep evaluating to see what we can do. In particular, we support
4467	// folding of const floating-point types, in order to make static const
4468	// data members of such types (supported as an extension) more useful.
4469	if (Info.getLangOpts().CPlusPlus) {
4470	Info.CCEDiag(E, Info.getLangOpts().CPlusPlus11
4471	? diag::note_constexpr_ltor_non_constexpr
4472	: diag::note_constexpr_ltor_non_integral, 1)
4473	<< VD << BaseType;
4474	Info.Note(VD->getLocation(), diag::note_declared_at);
4475	} else {
4476	Info.CCEDiag(E);
4477	}
4478	} else {
4479	// Never allow reading a non-const value.
4480	if (Info.getLangOpts().CPlusPlus) {
4481	Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
4482	? diag::note_constexpr_ltor_non_constexpr
4483	: diag::note_constexpr_ltor_non_integral, 1)
4484	<< VD << BaseType;
4485	Info.Note(VD->getLocation(), diag::note_declared_at);
4486	} else {
4487	Info.FFDiag(E);
4488	}
4489	return CompleteObject();
4490	}
4491	}
4492
4493	if (!evaluateVarDeclInit(Info, E, VD, Frame, Version: LVal.getLValueVersion(), Result&: BaseVal))
4494	return CompleteObject();
4495	} else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) {
4496	std::optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA);
4497	if (!Alloc) {
4498	Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK;
4499	return CompleteObject();
4500	}
4501	return CompleteObject(LVal.Base, &(*Alloc)->Value,
4502	LVal.Base.getDynamicAllocType());
4503	} else {
4504	const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4505
4506	if (!Frame) {
4507	if (const MaterializeTemporaryExpr *MTE =
4508	dyn_cast_or_null<MaterializeTemporaryExpr>(Val: Base)) {
4509	assert(MTE->getStorageDuration() == SD_Static &&
4510	"should have a frame for a non-global materialized temporary");
4511
4512	// C++20 [expr.const]p4: [DR2126]
4513	// An object or reference is usable in constant expressions if it is
4514	// - a temporary object of non-volatile const-qualified literal type
4515	// whose lifetime is extended to that of a variable that is usable
4516	// in constant expressions
4517	//
4518	// C++20 [expr.const]p5:
4519	// an lvalue-to-rvalue conversion [is not allowed unless it applies to]
4520	// - a non-volatile glvalue that refers to an object that is usable
4521	// in constant expressions, or
4522	// - a non-volatile glvalue of literal type that refers to a
4523	// non-volatile object whose lifetime began within the evaluation
4524	// of E;
4525	//
4526	// C++11 misses the 'began within the evaluation of e' check and
4527	// instead allows all temporaries, including things like:
4528	// int &&r = 1;
4529	// int x = ++r;
4530	// constexpr int k = r;
4531	// Therefore we use the C++14-onwards rules in C++11 too.
4532	//
4533	// Note that temporaries whose lifetimes began while evaluating a
4534	// variable's constructor are not usable while evaluating the
4535	// corresponding destructor, not even if they're of const-qualified
4536	// types.
4537	if (!MTE->isUsableInConstantExpressions(Context: Info.Ctx) &&
4538	!lifetimeStartedInEvaluation(Info, Base: LVal.Base)) {
4539	if (!IsAccess)
4540	return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4541	Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
4542	Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
4543	return CompleteObject();
4544	}
4545
4546	BaseVal = MTE->getOrCreateValue(MayCreate: false);
4547	assert(BaseVal && "got reference to unevaluated temporary");
4548	} else {
4549	if (!IsAccess)
4550	return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
4551	APValue Val;
4552	LVal.moveInto(V&: Val);
4553	Info.FFDiag(E, diag::note_constexpr_access_unreadable_object)
4554	<< AK
4555	<< Val.getAsString(Info.Ctx,
4556	Info.Ctx.getLValueReferenceType(LValType));
4557	NoteLValueLocation(Info, Base: LVal.Base);
4558	return CompleteObject();
4559	}
4560	} else {
4561	BaseVal = Frame->getTemporary(Key: Base, Version: LVal.Base.getVersion());
4562	assert(BaseVal && "missing value for temporary");
4563	}
4564	}
4565
4566	// In C++14, we can't safely access any mutable state when we might be
4567	// evaluating after an unmodeled side effect. Parameters are modeled as state
4568	// in the caller, but aren't visible once the call returns, so they can be
4569	// modified in a speculatively-evaluated call.
4570	//
4571	// FIXME: Not all local state is mutable. Allow local constant subobjects
4572	// to be read here (but take care with 'mutable' fields).
4573	unsigned VisibleDepth = Depth;
4574	if (llvm::isa_and_nonnull<ParmVarDecl>(
4575	Val: LVal.Base.dyn_cast<const ValueDecl *>()))
4576	++VisibleDepth;
4577	if ((Frame && Info.getLangOpts().CPlusPlus14 &&
4578	Info.EvalStatus.HasSideEffects) ||
4579	(isModification(AK) && VisibleDepth < Info.SpeculativeEvaluationDepth))
4580	return CompleteObject();
4581
4582	return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType);
4583	}
4584
4585	/// Perform an lvalue-to-rvalue conversion on the given glvalue. This
4586	/// can also be used for 'lvalue-to-lvalue' conversions for looking up the
4587	/// glvalue referred to by an entity of reference type.
4588	///
4589	/// \param Info - Information about the ongoing evaluation.
4590	/// \param Conv - The expression for which we are performing the conversion.
4591	/// Used for diagnostics.
4592	/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
4593	/// case of a non-class type).
4594	/// \param LVal - The glvalue on which we are attempting to perform this action.
4595	/// \param RVal - The produced value will be placed here.
4596	/// \param WantObjectRepresentation - If true, we're looking for the object
4597	/// representation rather than the value, and in particular,
4598	/// there is no requirement that the result be fully initialized.
4599	static bool
4600	handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type,
4601	const LValue &LVal, APValue &RVal,
4602	bool WantObjectRepresentation = false) {
4603	if (LVal.Designator.Invalid)
4604	return false;
4605
4606	// Check for special cases where there is no existing APValue to look at.
4607	const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
4608
4609	AccessKinds AK =
4610	WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read;
4611
4612	if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
4613	if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Val: Base)) {
4614	// In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
4615	// initializer until now for such expressions. Such an expression can't be
4616	// an ICE in C, so this only matters for fold.
4617	if (Type.isVolatileQualified()) {
4618	Info.FFDiag(E: Conv);
4619	return false;
4620	}
4621
4622	APValue Lit;
4623	if (!Evaluate(Result&: Lit, Info, E: CLE->getInitializer()))
4624	return false;
4625
4626	// According to GCC info page:
4627	//
4628	// 6.28 Compound Literals
4629	//
4630	// As an optimization, G++ sometimes gives array compound literals longer
4631	// lifetimes: when the array either appears outside a function or has a
4632	// const-qualified type. If foo and its initializer had elements of type
4633	// char *const rather than char *, or if foo were a global variable, the
4634	// array would have static storage duration. But it is probably safest
4635	// just to avoid the use of array compound literals in C++ code.
4636	//
4637	// Obey that rule by checking constness for converted array types.
4638
4639	QualType CLETy = CLE->getType();
4640	if (CLETy->isArrayType() && !Type->isArrayType()) {
4641	if (!CLETy.isConstant(Ctx: Info.Ctx)) {
4642	Info.FFDiag(E: Conv);
4643	Info.Note(CLE->getExprLoc(), diag::note_declared_at);
4644	return false;
4645	}
4646	}
4647
4648	CompleteObject LitObj(LVal.Base, &Lit, Base->getType());
4649	return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK);
4650	} else if (isa<StringLiteral>(Val: Base) || isa<PredefinedExpr>(Val: Base)) {
4651	// Special-case character extraction so we don't have to construct an
4652	// APValue for the whole string.
4653	assert(LVal.Designator.Entries.size() <= 1 &&
4654	"Can only read characters from string literals");
4655	if (LVal.Designator.Entries.empty()) {
4656	// Fail for now for LValue to RValue conversion of an array.
4657	// (This shouldn't show up in C/C++, but it could be triggered by a
4658	// weird EvaluateAsRValue call from a tool.)
4659	Info.FFDiag(E: Conv);
4660	return false;
4661	}
4662	if (LVal.Designator.isOnePastTheEnd()) {
4663	if (Info.getLangOpts().CPlusPlus11)
4664	Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK;
4665	else
4666	Info.FFDiag(E: Conv);
4667	return false;
4668	}
4669	uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex();
4670	RVal = APValue(extractStringLiteralCharacter(Info, Lit: Base, Index: CharIndex));
4671	return true;
4672	}
4673	}
4674
4675	CompleteObject Obj = findCompleteObject(Info, E: Conv, AK, LVal, LValType: Type);
4676	return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK);
4677	}
4678
4679	/// Perform an assignment of Val to LVal. Takes ownership of Val.
4680	static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
4681	QualType LValType, APValue &Val) {
4682	if (LVal.Designator.Invalid)
4683	return false;
4684
4685	if (!Info.getLangOpts().CPlusPlus14) {
4686	Info.FFDiag(E);
4687	return false;
4688	}
4689
4690	CompleteObject Obj = findCompleteObject(Info, E, AK: AK_Assign, LVal, LValType);
4691	return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
4692	}
4693
4694	namespace {
4695	struct CompoundAssignSubobjectHandler {
4696	EvalInfo &Info;
4697	const CompoundAssignOperator *E;
4698	QualType PromotedLHSType;
4699	BinaryOperatorKind Opcode;
4700	const APValue &RHS;
4701
4702	static const AccessKinds AccessKind = AK_Assign;
4703
4704	typedef bool result_type;
4705
4706	bool checkConst(QualType QT) {
4707	// Assigning to a const object has undefined behavior.
4708	if (QT.isConstQualified()) {
4709	Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4710	return false;
4711	}
4712	return true;
4713	}
4714
4715	bool failed() { return false; }
4716	bool found(APValue &Subobj, QualType SubobjType) {
4717	switch (Subobj.getKind()) {
4718	case APValue::Int:
4719	return found(Value&: Subobj.getInt(), SubobjType);
4720	case APValue::Float:
4721	return found(Value&: Subobj.getFloat(), SubobjType);
4722	case APValue::ComplexInt:
4723	case APValue::ComplexFloat:
4724	// FIXME: Implement complex compound assignment.
4725	Info.FFDiag(E);
4726	return false;
4727	case APValue::LValue:
4728	return foundPointer(Subobj, SubobjType);
4729	case APValue::Vector:
4730	return foundVector(Value&: Subobj, SubobjType);
4731	case APValue::Indeterminate:
4732	Info.FFDiag(E, diag::note_constexpr_access_uninit)
4733	<< /*read of=*/0 << /*uninitialized object=*/1
4734	<< E->getLHS()->getSourceRange();
4735	return false;
4736	default:
4737	// FIXME: can this happen?
4738	Info.FFDiag(E);
4739	return false;
4740	}
4741	}
4742
4743	bool foundVector(APValue &Value, QualType SubobjType) {
4744	if (!checkConst(QT: SubobjType))
4745	return false;
4746
4747	if (!SubobjType->isVectorType()) {
4748	Info.FFDiag(E);
4749	return false;
4750	}
4751	return handleVectorVectorBinOp(Info, E, Opcode, Value, RHS);
4752	}
4753
4754	bool found(APSInt &Value, QualType SubobjType) {
4755	if (!checkConst(QT: SubobjType))
4756	return false;
4757
4758	if (!SubobjType->isIntegerType()) {
4759	// We don't support compound assignment on integer-cast-to-pointer
4760	// values.
4761	Info.FFDiag(E);
4762	return false;
4763	}
4764
4765	if (RHS.isInt()) {
4766	APSInt LHS =
4767	HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
4768	if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
4769	return false;
4770	Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
4771	return true;
4772	} else if (RHS.isFloat()) {
4773	const FPOptions FPO = E->getFPFeaturesInEffect(
4774	Info.Ctx.getLangOpts());
4775	APFloat FValue(0.0);
4776	return HandleIntToFloatCast(Info, E, FPO, SubobjType, Value,
4777	PromotedLHSType, FValue) &&
4778	handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
4779	HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
4780	Value);
4781	}
4782
4783	Info.FFDiag(E);
4784	return false;
4785	}
4786	bool found(APFloat &Value, QualType SubobjType) {
4787	return checkConst(SubobjType) &&
4788	HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
4789	Value) &&
4790	handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
4791	HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
4792	}
4793	bool foundPointer(APValue &Subobj, QualType SubobjType) {
4794	if (!checkConst(QT: SubobjType))
4795	return false;
4796
4797	QualType PointeeType;
4798	if (const PointerType *PT = SubobjType->getAs<PointerType>())
4799	PointeeType = PT->getPointeeType();
4800
4801	if (PointeeType.isNull() || !RHS.isInt() ||
4802	(Opcode != BO_Add && Opcode != BO_Sub)) {
4803	Info.FFDiag(E);
4804	return false;
4805	}
4806
4807	APSInt Offset = RHS.getInt();
4808	if (Opcode == BO_Sub)
4809	negateAsSigned(Int&: Offset);
4810
4811	LValue LVal;
4812	LVal.setFrom(Ctx&: Info.Ctx, V: Subobj);
4813	if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
4814	return false;
4815	LVal.moveInto(V&: Subobj);
4816	return true;
4817	}
4818	};
4819	} // end anonymous namespace
4820
4821	const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
4822
4823	/// Perform a compound assignment of LVal <op>= RVal.
4824	static bool handleCompoundAssignment(EvalInfo &Info,
4825	const CompoundAssignOperator *E,
4826	const LValue &LVal, QualType LValType,
4827	QualType PromotedLValType,
4828	BinaryOperatorKind Opcode,
4829	const APValue &RVal) {
4830	if (LVal.Designator.Invalid)
4831	return false;
4832
4833	if (!Info.getLangOpts().CPlusPlus14) {
4834	Info.FFDiag(E);
4835	return false;
4836	}
4837
4838	CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
4839	CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
4840	RVal };
4841	return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4842	}
4843
4844	namespace {
4845	struct IncDecSubobjectHandler {
4846	EvalInfo &Info;
4847	const UnaryOperator *E;
4848	AccessKinds AccessKind;
4849	APValue *Old;
4850
4851	typedef bool result_type;
4852
4853	bool checkConst(QualType QT) {
4854	// Assigning to a const object has undefined behavior.
4855	if (QT.isConstQualified()) {
4856	Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
4857	return false;
4858	}
4859	return true;
4860	}
4861
4862	bool failed() { return false; }
4863	bool found(APValue &Subobj, QualType SubobjType) {
4864	// Stash the old value. Also clear Old, so we don't clobber it later
4865	// if we're post-incrementing a complex.
4866	if (Old) {
4867	*Old = Subobj;
4868	Old = nullptr;
4869	}
4870
4871	switch (Subobj.getKind()) {
4872	case APValue::Int:
4873	return found(Value&: Subobj.getInt(), SubobjType);
4874	case APValue::Float:
4875	return found(Value&: Subobj.getFloat(), SubobjType);
4876	case APValue::ComplexInt:
4877	return found(Value&: Subobj.getComplexIntReal(),
4878	SubobjType: SubobjType->castAs<ComplexType>()->getElementType()
4879	.withCVRQualifiers(CVR: SubobjType.getCVRQualifiers()));
4880	case APValue::ComplexFloat:
4881	return found(Value&: Subobj.getComplexFloatReal(),
4882	SubobjType: SubobjType->castAs<ComplexType>()->getElementType()
4883	.withCVRQualifiers(CVR: SubobjType.getCVRQualifiers()));
4884	case APValue::LValue:
4885	return foundPointer(Subobj, SubobjType);
4886	default:
4887	// FIXME: can this happen?
4888	Info.FFDiag(E);
4889	return false;
4890	}
4891	}
4892	bool found(APSInt &Value, QualType SubobjType) {
4893	if (!checkConst(QT: SubobjType))
4894	return false;
4895
4896	if (!SubobjType->isIntegerType()) {
4897	// We don't support increment / decrement on integer-cast-to-pointer
4898	// values.
4899	Info.FFDiag(E);
4900	return false;
4901	}
4902
4903	if (Old) *Old = APValue(Value);
4904
4905	// bool arithmetic promotes to int, and the conversion back to bool
4906	// doesn't reduce mod 2^n, so special-case it.
4907	if (SubobjType->isBooleanType()) {
4908	if (AccessKind == AK_Increment)
4909	Value = 1;
4910	else
4911	Value = !Value;
4912	return true;
4913	}
4914
4915	bool WasNegative = Value.isNegative();
4916	if (AccessKind == AK_Increment) {
4917	++Value;
4918
4919	if (!WasNegative && Value.isNegative() && E->canOverflow()) {
4920	APSInt ActualValue(Value, /*IsUnsigned*/true);
4921	return HandleOverflow(Info, E, ActualValue, SubobjType);
4922	}
4923	} else {
4924	--Value;
4925
4926	if (WasNegative && !Value.isNegative() && E->canOverflow()) {
4927	unsigned BitWidth = Value.getBitWidth();
4928	APSInt ActualValue(Value.sext(width: BitWidth + 1), /*IsUnsigned*/false);
4929	ActualValue.setBit(BitWidth);
4930	return HandleOverflow(Info, E, ActualValue, SubobjType);
4931	}
4932	}
4933	return true;
4934	}
4935	bool found(APFloat &Value, QualType SubobjType) {
4936	if (!checkConst(QT: SubobjType))
4937	return false;
4938
4939	if (Old) *Old = APValue(Value);
4940
4941	APFloat One(Value.getSemantics(), 1);
4942	llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
4943	APFloat::opStatus St;
4944	if (AccessKind == AK_Increment)
4945	St = Value.add(RHS: One, RM);
4946	else
4947	St = Value.subtract(RHS: One, RM);
4948	return checkFloatingPointResult(Info, E, St);
4949	}
4950	bool foundPointer(APValue &Subobj, QualType SubobjType) {
4951	if (!checkConst(QT: SubobjType))
4952	return false;
4953
4954	QualType PointeeType;
4955	if (const PointerType *PT = SubobjType->getAs<PointerType>())
4956	PointeeType = PT->getPointeeType();
4957	else {
4958	Info.FFDiag(E);
4959	return false;
4960	}
4961
4962	LValue LVal;
4963	LVal.setFrom(Ctx&: Info.Ctx, V: Subobj);
4964	if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
4965	AccessKind == AK_Increment ? 1 : -1))
4966	return false;
4967	LVal.moveInto(V&: Subobj);
4968	return true;
4969	}
4970	};
4971	} // end anonymous namespace
4972
4973	/// Perform an increment or decrement on LVal.
4974	static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
4975	QualType LValType, bool IsIncrement, APValue *Old) {
4976	if (LVal.Designator.Invalid)
4977	return false;
4978
4979	if (!Info.getLangOpts().CPlusPlus14) {
4980	Info.FFDiag(E);
4981	return false;
4982	}
4983
4984	AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
4985	CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
4986	IncDecSubobjectHandler Handler = {.Info: Info, .E: cast<UnaryOperator>(Val: E), .AccessKind: AK, .Old: Old};
4987	return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
4988	}
4989
4990	/// Build an lvalue for the object argument of a member function call.
4991	static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
4992	LValue &This) {
4993	if (Object->getType()->isPointerType() && Object->isPRValue())
4994	return EvaluatePointer(E: Object, Result&: This, Info);
4995
4996	if (Object->isGLValue())
4997	return EvaluateLValue(E: Object, Result&: This, Info);
4998
4999	if (Object->getType()->isLiteralType(Ctx: Info.Ctx))
5000	return EvaluateTemporary(E: Object, Result&: This, Info);
5001
5002	if (Object->getType()->isRecordType() && Object->isPRValue())
5003	return EvaluateTemporary(E: Object, Result&: This, Info);
5004
5005	Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
5006	return false;
5007	}
5008
5009	/// HandleMemberPointerAccess - Evaluate a member access operation and build an
5010	/// lvalue referring to the result.
5011	///
5012	/// \param Info - Information about the ongoing evaluation.
5013	/// \param LV - An lvalue referring to the base of the member pointer.
5014	/// \param RHS - The member pointer expression.
5015	/// \param IncludeMember - Specifies whether the member itself is included in
5016	/// the resulting LValue subobject designator. This is not possible when
5017	/// creating a bound member function.
5018	/// \return The field or method declaration to which the member pointer refers,
5019	/// or 0 if evaluation fails.
5020	static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
5021	QualType LVType,
5022	LValue &LV,
5023	const Expr *RHS,
5024	bool IncludeMember = true) {
5025	MemberPtr MemPtr;
5026	if (!EvaluateMemberPointer(E: RHS, Result&: MemPtr, Info))
5027	return nullptr;
5028
5029	// C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
5030	// member value, the behavior is undefined.
5031	if (!MemPtr.getDecl()) {
5032	// FIXME: Specific diagnostic.
5033	Info.FFDiag(E: RHS);
5034	return nullptr;
5035	}
5036
5037	if (MemPtr.isDerivedMember()) {
5038	// This is a member of some derived class. Truncate LV appropriately.
5039	// The end of the derived-to-base path for the base object must match the
5040	// derived-to-base path for the member pointer.
5041	if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
5042	LV.Designator.Entries.size()) {
5043	Info.FFDiag(E: RHS);
5044	return nullptr;
5045	}
5046	unsigned PathLengthToMember =
5047	LV.Designator.Entries.size() - MemPtr.Path.size();
5048	for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
5049	const CXXRecordDecl *LVDecl = getAsBaseClass(
5050	LV.Designator.Entries[PathLengthToMember + I]);
5051	const CXXRecordDecl *MPDecl = MemPtr.Path[I];
5052	if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
5053	Info.FFDiag(E: RHS);
5054	return nullptr;
5055	}
5056	}
5057
5058	// Truncate the lvalue to the appropriate derived class.
5059	if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
5060	PathLengthToMember))
5061	return nullptr;
5062	} else if (!MemPtr.Path.empty()) {
5063	// Extend the LValue path with the member pointer's path.
5064	LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
5065	MemPtr.Path.size() + IncludeMember);
5066
5067	// Walk down to the appropriate base class.
5068	if (const PointerType *PT = LVType->getAs<PointerType>())
5069	LVType = PT->getPointeeType();
5070	const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
5071	assert(RD && "member pointer access on non-class-type expression");
5072	// The first class in the path is that of the lvalue.
5073	for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
5074	const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
5075	if (!HandleLValueDirectBase(Info, E: RHS, Obj&: LV, Derived: RD, Base))
5076	return nullptr;
5077	RD = Base;
5078	}
5079	// Finally cast to the class containing the member.
5080	if (!HandleLValueDirectBase(Info, E: RHS, Obj&: LV, Derived: RD,
5081	Base: MemPtr.getContainingRecord()))
5082	return nullptr;
5083	}
5084
5085	// Add the member. Note that we cannot build bound member functions here.
5086	if (IncludeMember) {
5087	if (const FieldDecl *FD = dyn_cast<FieldDecl>(Val: MemPtr.getDecl())) {
5088	if (!HandleLValueMember(Info, E: RHS, LVal&: LV, FD))
5089	return nullptr;
5090	} else if (const IndirectFieldDecl *IFD =
5091	dyn_cast<IndirectFieldDecl>(Val: MemPtr.getDecl())) {
5092	if (!HandleLValueIndirectMember(Info, E: RHS, LVal&: LV, IFD))
5093	return nullptr;
5094	} else {
5095	llvm_unreachable("can't construct reference to bound member function");
5096	}
5097	}
5098
5099	return MemPtr.getDecl();
5100	}
5101
5102	static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
5103	const BinaryOperator *BO,
5104	LValue &LV,
5105	bool IncludeMember = true) {
5106	assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI);
5107
5108	if (!EvaluateObjectArgument(Info, Object: BO->getLHS(), This&: LV)) {
5109	if (Info.noteFailure()) {
5110	MemberPtr MemPtr;
5111	EvaluateMemberPointer(E: BO->getRHS(), Result&: MemPtr, Info);
5112	}
5113	return nullptr;
5114	}
5115
5116	return HandleMemberPointerAccess(Info, LVType: BO->getLHS()->getType(), LV,
5117	RHS: BO->getRHS(), IncludeMember);
5118	}
5119
5120	/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
5121	/// the provided lvalue, which currently refers to the base object.
5122	static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
5123	LValue &Result) {
5124	SubobjectDesignator &D = Result.Designator;
5125	if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
5126	return false;
5127
5128	QualType TargetQT = E->getType();
5129	if (const PointerType *PT = TargetQT->getAs<PointerType>())
5130	TargetQT = PT->getPointeeType();
5131
5132	// Check this cast lands within the final derived-to-base subobject path.
5133	if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
5134	Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
5135	<< D.MostDerivedType << TargetQT;
5136	return false;
5137	}
5138
5139	// Check the type of the final cast. We don't need to check the path,
5140	// since a cast can only be formed if the path is unique.
5141	unsigned NewEntriesSize = D.Entries.size() - E->path_size();
5142	const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
5143	const CXXRecordDecl *FinalType;
5144	if (NewEntriesSize == D.MostDerivedPathLength)
5145	FinalType = D.MostDerivedType->getAsCXXRecordDecl();
5146	else
5147	FinalType = getAsBaseClass(E: D.Entries[NewEntriesSize - 1]);
5148	if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
5149	Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
5150	<< D.MostDerivedType << TargetQT;
5151	return false;
5152	}
5153
5154	// Truncate the lvalue to the appropriate derived class.
5155	return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
5156	}
5157
5158	/// Get the value to use for a default-initialized object of type T.
5159	/// Return false if it encounters something invalid.
5160	static bool handleDefaultInitValue(QualType T, APValue &Result) {
5161	bool Success = true;
5162
5163	// If there is already a value present don't overwrite it.
5164	if (!Result.isAbsent())
5165	return true;
5166
5167	if (auto *RD = T->getAsCXXRecordDecl()) {
5168	if (RD->isInvalidDecl()) {
5169	Result = APValue();
5170	return false;
5171	}
5172	if (RD->isUnion()) {
5173	Result = APValue((const FieldDecl *)nullptr);
5174	return true;
5175	}
5176	Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
5177	std::distance(RD->field_begin(), RD->field_end()));
5178
5179	unsigned Index = 0;
5180	for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
5181	End = RD->bases_end();
5182	I != End; ++I, ++Index)
5183	Success &=
5184	handleDefaultInitValue(T: I->getType(), Result&: Result.getStructBase(i: Index));
5185
5186	for (const auto *I : RD->fields()) {
5187	if (I->isUnnamedBitField())
5188	continue;
5189	Success &= handleDefaultInitValue(
5190	I->getType(), Result.getStructField(I->getFieldIndex()));
5191	}
5192	return Success;
5193	}
5194
5195	if (auto *AT =
5196	dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
5197	Result = APValue(APValue::UninitArray(), 0, AT->getZExtSize());
5198	if (Result.hasArrayFiller())
5199	Success &=
5200	handleDefaultInitValue(AT->getElementType(), Result.getArrayFiller());
5201
5202	return Success;
5203	}
5204
5205	Result = APValue::IndeterminateValue();
5206	return true;
5207	}
5208
5209	namespace {
5210	enum EvalStmtResult {
5211	/// Evaluation failed.
5212	ESR_Failed,
5213	/// Hit a 'return' statement.
5214	ESR_Returned,
5215	/// Evaluation succeeded.
5216	ESR_Succeeded,
5217	/// Hit a 'continue' statement.
5218	ESR_Continue,
5219	/// Hit a 'break' statement.
5220	ESR_Break,
5221	/// Still scanning for 'case' or 'default' statement.
5222	ESR_CaseNotFound
5223	};
5224	}
5225
5226	static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
5227	if (VD->isInvalidDecl())
5228	return false;
5229	// We don't need to evaluate the initializer for a static local.
5230	if (!VD->hasLocalStorage())
5231	return true;
5232
5233	LValue Result;
5234	APValue &Val = Info.CurrentCall->createTemporary(VD, VD->getType(),
5235	ScopeKind::Block, Result);
5236
5237	const Expr *InitE = VD->getInit();
5238	if (!InitE) {
5239	if (VD->getType()->isDependentType())
5240	return Info.noteSideEffect();
5241	return handleDefaultInitValue(VD->getType(), Val);
5242	}
5243	if (InitE->isValueDependent())
5244	return false;
5245
5246	if (!EvaluateInPlace(Result&: Val, Info, This: Result, E: InitE)) {
5247	// Wipe out any partially-computed value, to allow tracking that this
5248	// evaluation failed.
5249	Val = APValue();
5250	return false;
5251	}
5252
5253	return true;
5254	}
5255
5256	static bool EvaluateDecompositionDeclInit(EvalInfo &Info,
5257	const DecompositionDecl *DD);
5258
5259	static bool EvaluateDecl(EvalInfo &Info, const Decl *D,
5260	bool EvaluateConditionDecl = false) {
5261	bool OK = true;
5262	if (const VarDecl *VD = dyn_cast<VarDecl>(Val: D))
5263	OK &= EvaluateVarDecl(Info, VD);
5264
5265	if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(Val: D);
5266	EvaluateConditionDecl && DD)
5267	OK &= EvaluateDecompositionDeclInit(Info, DD);
5268
5269	return OK;
5270	}
5271
5272	static bool EvaluateDecompositionDeclInit(EvalInfo &Info,
5273	const DecompositionDecl *DD) {
5274	bool OK = true;
5275	for (auto *BD : DD->flat_bindings())
5276	if (auto *VD = BD->getHoldingVar())
5277	OK &= EvaluateDecl(Info, VD, /*EvaluateConditionDecl=*/true);
5278
5279	return OK;
5280	}
5281
5282	static bool MaybeEvaluateDeferredVarDeclInit(EvalInfo &Info,
5283	const VarDecl *VD) {
5284	if (auto *DD = dyn_cast_if_present<DecompositionDecl>(Val: VD)) {
5285	if (!EvaluateDecompositionDeclInit(Info, DD))
5286	return false;
5287	}
5288	return true;
5289	}
5290
5291	static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) {
5292	assert(E->isValueDependent());
5293	if (Info.noteSideEffect())
5294	return true;
5295	assert(E->containsErrors() && "valid value-dependent expression should never "
5296	"reach invalid code path.");
5297	return false;
5298	}
5299
5300	/// Evaluate a condition (either a variable declaration or an expression).
5301	static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
5302	const Expr *Cond, bool &Result) {
5303	if (Cond->isValueDependent())
5304	return false;
5305	FullExpressionRAII Scope(Info);
5306	if (CondDecl && !EvaluateDecl(Info, CondDecl))
5307	return false;
5308	if (!EvaluateAsBooleanCondition(E: Cond, Result, Info))
5309	return false;
5310	if (!MaybeEvaluateDeferredVarDeclInit(Info, VD: CondDecl))
5311	return false;
5312	return Scope.destroy();
5313	}
5314
5315	namespace {
5316	/// A location where the result (returned value) of evaluating a
5317	/// statement should be stored.
5318	struct StmtResult {
5319	/// The APValue that should be filled in with the returned value.
5320	APValue &Value;
5321	/// The location containing the result, if any (used to support RVO).
5322	const LValue *Slot;
5323	};
5324
5325	struct TempVersionRAII {
5326	CallStackFrame &Frame;
5327
5328	TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
5329	Frame.pushTempVersion();
5330	}
5331
5332	~TempVersionRAII() {
5333	Frame.popTempVersion();
5334	}
5335	};
5336
5337	}
5338
5339	static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
5340	const Stmt *S,
5341	const SwitchCase *SC = nullptr);
5342
5343	/// Evaluate the body of a loop, and translate the result as appropriate.
5344	static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
5345	const Stmt *Body,
5346	const SwitchCase *Case = nullptr) {
5347	BlockScopeRAII Scope(Info);
5348
5349	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: Body, SC: Case);
5350	if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
5351	ESR = ESR_Failed;
5352
5353	switch (ESR) {
5354	case ESR_Break:
5355	return ESR_Succeeded;
5356	case ESR_Succeeded:
5357	case ESR_Continue:
5358	return ESR_Continue;
5359	case ESR_Failed:
5360	case ESR_Returned:
5361	case ESR_CaseNotFound:
5362	return ESR;
5363	}
5364	llvm_unreachable("Invalid EvalStmtResult!");
5365	}
5366
5367	/// Evaluate a switch statement.
5368	static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
5369	const SwitchStmt *SS) {
5370	BlockScopeRAII Scope(Info);
5371
5372	// Evaluate the switch condition.
5373	APSInt Value;
5374	{
5375	if (const Stmt *Init = SS->getInit()) {
5376	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: Init);
5377	if (ESR != ESR_Succeeded) {
5378	if (ESR != ESR_Failed && !Scope.destroy())
5379	ESR = ESR_Failed;
5380	return ESR;
5381	}
5382	}
5383
5384	FullExpressionRAII CondScope(Info);
5385	if (SS->getConditionVariable() &&
5386	!EvaluateDecl(Info, SS->getConditionVariable()))
5387	return ESR_Failed;
5388	if (SS->getCond()->isValueDependent()) {
5389	// We don't know what the value is, and which branch should jump to.
5390	EvaluateDependentExpr(E: SS->getCond(), Info);
5391	return ESR_Failed;
5392	}
5393	if (!EvaluateInteger(E: SS->getCond(), Result&: Value, Info))
5394	return ESR_Failed;
5395
5396	if (!MaybeEvaluateDeferredVarDeclInit(Info, VD: SS->getConditionVariable()))
5397	return ESR_Failed;
5398
5399	if (!CondScope.destroy())
5400	return ESR_Failed;
5401	}
5402
5403	// Find the switch case corresponding to the value of the condition.
5404	// FIXME: Cache this lookup.
5405	const SwitchCase *Found = nullptr;
5406	for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
5407	SC = SC->getNextSwitchCase()) {
5408	if (isa<DefaultStmt>(Val: SC)) {
5409	Found = SC;
5410	continue;
5411	}
5412
5413	const CaseStmt *CS = cast<CaseStmt>(Val: SC);
5414	APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Ctx: Info.Ctx);
5415	APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Ctx: Info.Ctx)
5416	: LHS;
5417	if (LHS <= Value && Value <= RHS) {
5418	Found = SC;
5419	break;
5420	}
5421	}
5422
5423	if (!Found)
5424	return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5425
5426	// Search the switch body for the switch case and evaluate it from there.
5427	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: SS->getBody(), SC: Found);
5428	if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
5429	return ESR_Failed;
5430
5431	switch (ESR) {
5432	case ESR_Break:
5433	return ESR_Succeeded;
5434	case ESR_Succeeded:
5435	case ESR_Continue:
5436	case ESR_Failed:
5437	case ESR_Returned:
5438	return ESR;
5439	case ESR_CaseNotFound:
5440	// This can only happen if the switch case is nested within a statement
5441	// expression. We have no intention of supporting that.
5442	Info.FFDiag(Found->getBeginLoc(),
5443	diag::note_constexpr_stmt_expr_unsupported);
5444	return ESR_Failed;
5445	}
5446	llvm_unreachable("Invalid EvalStmtResult!");
5447	}
5448
5449	static bool CheckLocalVariableDeclaration(EvalInfo &Info, const VarDecl *VD) {
5450	// An expression E is a core constant expression unless the evaluation of E
5451	// would evaluate one of the following: [C++23] - a control flow that passes
5452	// through a declaration of a variable with static or thread storage duration
5453	// unless that variable is usable in constant expressions.
5454	if (VD->isLocalVarDecl() && VD->isStaticLocal() &&
5455	!VD->isUsableInConstantExpressions(C: Info.Ctx)) {
5456	Info.CCEDiag(VD->getLocation(), diag::note_constexpr_static_local)
5457	<< (VD->getTSCSpec() == TSCS_unspecified ? 0 : 1) << VD;
5458	return false;
5459	}
5460	return true;
5461	}
5462
5463	// Evaluate a statement.
5464	static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
5465	const Stmt *S, const SwitchCase *Case) {
5466	if (!Info.nextStep(S))
5467	return ESR_Failed;
5468
5469	// If we're hunting down a 'case' or 'default' label, recurse through
5470	// substatements until we hit the label.
5471	if (Case) {
5472	switch (S->getStmtClass()) {
5473	case Stmt::CompoundStmtClass:
5474	// FIXME: Precompute which substatement of a compound statement we
5475	// would jump to, and go straight there rather than performing a
5476	// linear scan each time.
5477	case Stmt::LabelStmtClass:
5478	case Stmt::AttributedStmtClass:
5479	case Stmt::DoStmtClass:
5480	break;
5481
5482	case Stmt::CaseStmtClass:
5483	case Stmt::DefaultStmtClass:
5484	if (Case == S)
5485	Case = nullptr;
5486	break;
5487
5488	case Stmt::IfStmtClass: {
5489	// FIXME: Precompute which side of an 'if' we would jump to, and go
5490	// straight there rather than scanning both sides.
5491	const IfStmt *IS = cast<IfStmt>(Val: S);
5492
5493	// Wrap the evaluation in a block scope, in case it's a DeclStmt
5494	// preceded by our switch label.
5495	BlockScopeRAII Scope(Info);
5496
5497	// Step into the init statement in case it brings an (uninitialized)
5498	// variable into scope.
5499	if (const Stmt *Init = IS->getInit()) {
5500	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: Init, Case);
5501	if (ESR != ESR_CaseNotFound) {
5502	assert(ESR != ESR_Succeeded);
5503	return ESR;
5504	}
5505	}
5506
5507	// Condition variable must be initialized if it exists.
5508	// FIXME: We can skip evaluating the body if there's a condition
5509	// variable, as there can't be any case labels within it.
5510	// (The same is true for 'for' statements.)
5511
5512	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: IS->getThen(), Case);
5513	if (ESR == ESR_Failed)
5514	return ESR;
5515	if (ESR != ESR_CaseNotFound)
5516	return Scope.destroy() ? ESR : ESR_Failed;
5517	if (!IS->getElse())
5518	return ESR_CaseNotFound;
5519
5520	ESR = EvaluateStmt(Result, Info, S: IS->getElse(), Case);
5521	if (ESR == ESR_Failed)
5522	return ESR;
5523	if (ESR != ESR_CaseNotFound)
5524	return Scope.destroy() ? ESR : ESR_Failed;
5525	return ESR_CaseNotFound;
5526	}
5527
5528	case Stmt::WhileStmtClass: {
5529	EvalStmtResult ESR =
5530	EvaluateLoopBody(Result, Info, Body: cast<WhileStmt>(Val: S)->getBody(), Case);
5531	if (ESR != ESR_Continue)
5532	return ESR;
5533	break;
5534	}
5535
5536	case Stmt::ForStmtClass: {
5537	const ForStmt *FS = cast<ForStmt>(Val: S);
5538	BlockScopeRAII Scope(Info);
5539
5540	// Step into the init statement in case it brings an (uninitialized)
5541	// variable into scope.
5542	if (const Stmt *Init = FS->getInit()) {
5543	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: Init, Case);
5544	if (ESR != ESR_CaseNotFound) {
5545	assert(ESR != ESR_Succeeded);
5546	return ESR;
5547	}
5548	}
5549
5550	EvalStmtResult ESR =
5551	EvaluateLoopBody(Result, Info, Body: FS->getBody(), Case);
5552	if (ESR != ESR_Continue)
5553	return ESR;
5554	if (const auto *Inc = FS->getInc()) {
5555	if (Inc->isValueDependent()) {
5556	if (!EvaluateDependentExpr(E: Inc, Info))
5557	return ESR_Failed;
5558	} else {
5559	FullExpressionRAII IncScope(Info);
5560	if (!EvaluateIgnoredValue(Info, E: Inc) || !IncScope.destroy())
5561	return ESR_Failed;
5562	}
5563	}
5564	break;
5565	}
5566
5567	case Stmt::DeclStmtClass: {
5568	// Start the lifetime of any uninitialized variables we encounter. They
5569	// might be used by the selected branch of the switch.
5570	const DeclStmt *DS = cast<DeclStmt>(Val: S);
5571	for (const auto *D : DS->decls()) {
5572	if (const auto *VD = dyn_cast<VarDecl>(Val: D)) {
5573	if (!CheckLocalVariableDeclaration(Info, VD))
5574	return ESR_Failed;
5575	if (VD->hasLocalStorage() && !VD->getInit())
5576	if (!EvaluateVarDecl(Info, VD))
5577	return ESR_Failed;
5578	// FIXME: If the variable has initialization that can't be jumped
5579	// over, bail out of any immediately-surrounding compound-statement
5580	// too. There can't be any case labels here.
5581	}
5582	}
5583	return ESR_CaseNotFound;
5584	}
5585
5586	default:
5587	return ESR_CaseNotFound;
5588	}
5589	}
5590
5591	switch (S->getStmtClass()) {
5592	default:
5593	if (const Expr *E = dyn_cast<Expr>(Val: S)) {
5594	if (E->isValueDependent()) {
5595	if (!EvaluateDependentExpr(E, Info))
5596	return ESR_Failed;
5597	} else {
5598	// Don't bother evaluating beyond an expression-statement which couldn't
5599	// be evaluated.
5600	// FIXME: Do we need the FullExpressionRAII object here?
5601	// VisitExprWithCleanups should create one when necessary.
5602	FullExpressionRAII Scope(Info);
5603	if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy())
5604	return ESR_Failed;
5605	}
5606	return ESR_Succeeded;
5607	}
5608
5609	Info.FFDiag(Loc: S->getBeginLoc()) << S->getSourceRange();
5610	return ESR_Failed;
5611
5612	case Stmt::NullStmtClass:
5613	return ESR_Succeeded;
5614
5615	case Stmt::DeclStmtClass: {
5616	const DeclStmt *DS = cast<DeclStmt>(Val: S);
5617	for (const auto *D : DS->decls()) {
5618	const VarDecl *VD = dyn_cast_or_null<VarDecl>(Val: D);
5619	if (VD && !CheckLocalVariableDeclaration(Info, VD))
5620	return ESR_Failed;
5621	// Each declaration initialization is its own full-expression.
5622	FullExpressionRAII Scope(Info);
5623	if (!EvaluateDecl(Info, D, /*EvaluateConditionDecl=*/true) &&
5624	!Info.noteFailure())
5625	return ESR_Failed;
5626	if (!Scope.destroy())
5627	return ESR_Failed;
5628	}
5629	return ESR_Succeeded;
5630	}
5631
5632	case Stmt::ReturnStmtClass: {
5633	const Expr *RetExpr = cast<ReturnStmt>(Val: S)->getRetValue();
5634	FullExpressionRAII Scope(Info);
5635	if (RetExpr && RetExpr->isValueDependent()) {
5636	EvaluateDependentExpr(E: RetExpr, Info);
5637	// We know we returned, but we don't know what the value is.
5638	return ESR_Failed;
5639	}
5640	if (RetExpr &&
5641	!(Result.Slot
5642	? EvaluateInPlace(Result&: Result.Value, Info, This: *Result.Slot, E: RetExpr)
5643	: Evaluate(Result&: Result.Value, Info, E: RetExpr)))
5644	return ESR_Failed;
5645	return Scope.destroy() ? ESR_Returned : ESR_Failed;
5646	}
5647
5648	case Stmt::CompoundStmtClass: {
5649	BlockScopeRAII Scope(Info);
5650
5651	const CompoundStmt *CS = cast<CompoundStmt>(Val: S);
5652	for (const auto *BI : CS->body()) {
5653	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: BI, Case);
5654	if (ESR == ESR_Succeeded)
5655	Case = nullptr;
5656	else if (ESR != ESR_CaseNotFound) {
5657	if (ESR != ESR_Failed && !Scope.destroy())
5658	return ESR_Failed;
5659	return ESR;
5660	}
5661	}
5662	if (Case)
5663	return ESR_CaseNotFound;
5664	return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5665	}
5666
5667	case Stmt::IfStmtClass: {
5668	const IfStmt *IS = cast<IfStmt>(Val: S);
5669
5670	// Evaluate the condition, as either a var decl or as an expression.
5671	BlockScopeRAII Scope(Info);
5672	if (const Stmt *Init = IS->getInit()) {
5673	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: Init);
5674	if (ESR != ESR_Succeeded) {
5675	if (ESR != ESR_Failed && !Scope.destroy())
5676	return ESR_Failed;
5677	return ESR;
5678	}
5679	}
5680	bool Cond;
5681	if (IS->isConsteval()) {
5682	Cond = IS->isNonNegatedConsteval();
5683	// If we are not in a constant context, if consteval should not evaluate
5684	// to true.
5685	if (!Info.InConstantContext)
5686	Cond = !Cond;
5687	} else if (!EvaluateCond(Info, CondDecl: IS->getConditionVariable(), Cond: IS->getCond(),
5688	Result&: Cond))
5689	return ESR_Failed;
5690
5691	if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
5692	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: SubStmt);
5693	if (ESR != ESR_Succeeded) {
5694	if (ESR != ESR_Failed && !Scope.destroy())
5695	return ESR_Failed;
5696	return ESR;
5697	}
5698	}
5699	return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5700	}
5701
5702	case Stmt::WhileStmtClass: {
5703	const WhileStmt *WS = cast<WhileStmt>(Val: S);
5704	while (true) {
5705	BlockScopeRAII Scope(Info);
5706	bool Continue;
5707	if (!EvaluateCond(Info, CondDecl: WS->getConditionVariable(), Cond: WS->getCond(),
5708	Result&: Continue))
5709	return ESR_Failed;
5710	if (!Continue)
5711	break;
5712
5713	EvalStmtResult ESR = EvaluateLoopBody(Result, Info, Body: WS->getBody());
5714	if (ESR != ESR_Continue) {
5715	if (ESR != ESR_Failed && !Scope.destroy())
5716	return ESR_Failed;
5717	return ESR;
5718	}
5719	if (!Scope.destroy())
5720	return ESR_Failed;
5721	}
5722	return ESR_Succeeded;
5723	}
5724
5725	case Stmt::DoStmtClass: {
5726	const DoStmt *DS = cast<DoStmt>(Val: S);
5727	bool Continue;
5728	do {
5729	EvalStmtResult ESR = EvaluateLoopBody(Result, Info, Body: DS->getBody(), Case);
5730	if (ESR != ESR_Continue)
5731	return ESR;
5732	Case = nullptr;
5733
5734	if (DS->getCond()->isValueDependent()) {
5735	EvaluateDependentExpr(E: DS->getCond(), Info);
5736	// Bailout as we don't know whether to keep going or terminate the loop.
5737	return ESR_Failed;
5738	}
5739	FullExpressionRAII CondScope(Info);
5740	if (!EvaluateAsBooleanCondition(E: DS->getCond(), Result&: Continue, Info) ||
5741	!CondScope.destroy())
5742	return ESR_Failed;
5743	} while (Continue);
5744	return ESR_Succeeded;
5745	}
5746
5747	case Stmt::ForStmtClass: {
5748	const ForStmt *FS = cast<ForStmt>(Val: S);
5749	BlockScopeRAII ForScope(Info);
5750	if (FS->getInit()) {
5751	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: FS->getInit());
5752	if (ESR != ESR_Succeeded) {
5753	if (ESR != ESR_Failed && !ForScope.destroy())
5754	return ESR_Failed;
5755	return ESR;
5756	}
5757	}
5758	while (true) {
5759	BlockScopeRAII IterScope(Info);
5760	bool Continue = true;
5761	if (FS->getCond() && !EvaluateCond(Info, CondDecl: FS->getConditionVariable(),
5762	Cond: FS->getCond(), Result&: Continue))
5763	return ESR_Failed;
5764
5765	if (!Continue) {
5766	if (!IterScope.destroy())
5767	return ESR_Failed;
5768	break;
5769	}
5770
5771	EvalStmtResult ESR = EvaluateLoopBody(Result, Info, Body: FS->getBody());
5772	if (ESR != ESR_Continue) {
5773	if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy()))
5774	return ESR_Failed;
5775	return ESR;
5776	}
5777
5778	if (const auto *Inc = FS->getInc()) {
5779	if (Inc->isValueDependent()) {
5780	if (!EvaluateDependentExpr(E: Inc, Info))
5781	return ESR_Failed;
5782	} else {
5783	FullExpressionRAII IncScope(Info);
5784	if (!EvaluateIgnoredValue(Info, E: Inc) || !IncScope.destroy())
5785	return ESR_Failed;
5786	}
5787	}
5788
5789	if (!IterScope.destroy())
5790	return ESR_Failed;
5791	}
5792	return ForScope.destroy() ? ESR_Succeeded : ESR_Failed;
5793	}
5794
5795	case Stmt::CXXForRangeStmtClass: {
5796	const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(Val: S);
5797	BlockScopeRAII Scope(Info);
5798
5799	// Evaluate the init-statement if present.
5800	if (FS->getInit()) {
5801	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: FS->getInit());
5802	if (ESR != ESR_Succeeded) {
5803	if (ESR != ESR_Failed && !Scope.destroy())
5804	return ESR_Failed;
5805	return ESR;
5806	}
5807	}
5808
5809	// Initialize the __range variable.
5810	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: FS->getRangeStmt());
5811	if (ESR != ESR_Succeeded) {
5812	if (ESR != ESR_Failed && !Scope.destroy())
5813	return ESR_Failed;
5814	return ESR;
5815	}
5816
5817	// In error-recovery cases it's possible to get here even if we failed to
5818	// synthesize the __begin and __end variables.
5819	if (!FS->getBeginStmt() || !FS->getEndStmt() || !FS->getCond())
5820	return ESR_Failed;
5821
5822	// Create the __begin and __end iterators.
5823	ESR = EvaluateStmt(Result, Info, S: FS->getBeginStmt());
5824	if (ESR != ESR_Succeeded) {
5825	if (ESR != ESR_Failed && !Scope.destroy())
5826	return ESR_Failed;
5827	return ESR;
5828	}
5829	ESR = EvaluateStmt(Result, Info, S: FS->getEndStmt());
5830	if (ESR != ESR_Succeeded) {
5831	if (ESR != ESR_Failed && !Scope.destroy())
5832	return ESR_Failed;
5833	return ESR;
5834	}
5835
5836	while (true) {
5837	// Condition: __begin != __end.
5838	{
5839	if (FS->getCond()->isValueDependent()) {
5840	EvaluateDependentExpr(E: FS->getCond(), Info);
5841	// We don't know whether to keep going or terminate the loop.
5842	return ESR_Failed;
5843	}
5844	bool Continue = true;
5845	FullExpressionRAII CondExpr(Info);
5846	if (!EvaluateAsBooleanCondition(E: FS->getCond(), Result&: Continue, Info))
5847	return ESR_Failed;
5848	if (!Continue)
5849	break;
5850	}
5851
5852	// User's variable declaration, initialized by *__begin.
5853	BlockScopeRAII InnerScope(Info);
5854	ESR = EvaluateStmt(Result, Info, S: FS->getLoopVarStmt());
5855	if (ESR != ESR_Succeeded) {
5856	if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5857	return ESR_Failed;
5858	return ESR;
5859	}
5860
5861	// Loop body.
5862	ESR = EvaluateLoopBody(Result, Info, Body: FS->getBody());
5863	if (ESR != ESR_Continue) {
5864	if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
5865	return ESR_Failed;
5866	return ESR;
5867	}
5868	if (FS->getInc()->isValueDependent()) {
5869	if (!EvaluateDependentExpr(E: FS->getInc(), Info))
5870	return ESR_Failed;
5871	} else {
5872	// Increment: ++__begin
5873	if (!EvaluateIgnoredValue(Info, E: FS->getInc()))
5874	return ESR_Failed;
5875	}
5876
5877	if (!InnerScope.destroy())
5878	return ESR_Failed;
5879	}
5880
5881	return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
5882	}
5883
5884	case Stmt::SwitchStmtClass:
5885	return EvaluateSwitch(Result, Info, SS: cast<SwitchStmt>(Val: S));
5886
5887	case Stmt::ContinueStmtClass:
5888	return ESR_Continue;
5889
5890	case Stmt::BreakStmtClass:
5891	return ESR_Break;
5892
5893	case Stmt::LabelStmtClass:
5894	return EvaluateStmt(Result, Info, S: cast<LabelStmt>(Val: S)->getSubStmt(), Case);
5895
5896	case Stmt::AttributedStmtClass: {
5897	const auto *AS = cast<AttributedStmt>(Val: S);
5898	const auto *SS = AS->getSubStmt();
5899	MSConstexprContextRAII ConstexprContext(
5900	*Info.CurrentCall, hasSpecificAttr<MSConstexprAttr>(AS->getAttrs()) &&
5901	isa<ReturnStmt>(SS));
5902
5903	auto LO = Info.getASTContext().getLangOpts();
5904	if (LO.CXXAssumptions && !LO.MSVCCompat) {
5905	for (auto *Attr : AS->getAttrs()) {
5906	auto *AA = dyn_cast<CXXAssumeAttr>(Attr);
5907	if (!AA)
5908	continue;
5909
5910	auto *Assumption = AA->getAssumption();
5911	if (Assumption->isValueDependent())
5912	return ESR_Failed;
5913
5914	if (Assumption->HasSideEffects(Info.getASTContext()))
5915	continue;
5916
5917	bool Value;
5918	if (!EvaluateAsBooleanCondition(Assumption, Value, Info))
5919	return ESR_Failed;
5920	if (!Value) {
5921	Info.CCEDiag(Assumption->getExprLoc(),
5922	diag::note_constexpr_assumption_failed);
5923	return ESR_Failed;
5924	}
5925	}
5926	}
5927
5928	return EvaluateStmt(Result, Info, S: SS, Case);
5929	}
5930
5931	case Stmt::CaseStmtClass:
5932	case Stmt::DefaultStmtClass:
5933	return EvaluateStmt(Result, Info, S: cast<SwitchCase>(Val: S)->getSubStmt(), Case);
5934	case Stmt::CXXTryStmtClass:
5935	// Evaluate try blocks by evaluating all sub statements.
5936	return EvaluateStmt(Result, Info, cast<CXXTryStmt>(Val: S)->getTryBlock(), Case);
5937	}
5938	}
5939
5940	/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
5941	/// default constructor. If so, we'll fold it whether or not it's marked as
5942	/// constexpr. If it is marked as constexpr, we will never implicitly define it,
5943	/// so we need special handling.
5944	static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
5945	const CXXConstructorDecl *CD,
5946	bool IsValueInitialization) {
5947	if (!CD->isTrivial() || !CD->isDefaultConstructor())
5948	return false;
5949
5950	// Value-initialization does not call a trivial default constructor, so such a
5951	// call is a core constant expression whether or not the constructor is
5952	// constexpr.
5953	if (!CD->isConstexpr() && !IsValueInitialization) {
5954	if (Info.getLangOpts().CPlusPlus11) {
5955	// FIXME: If DiagDecl is an implicitly-declared special member function,
5956	// we should be much more explicit about why it's not constexpr.
5957	Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
5958	<< /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
5959	Info.Note(CD->getLocation(), diag::note_declared_at);
5960	} else {
5961	Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
5962	}
5963	}
5964	return true;
5965	}
5966
5967	/// CheckConstexprFunction - Check that a function can be called in a constant
5968	/// expression.
5969	static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
5970	const FunctionDecl *Declaration,
5971	const FunctionDecl *Definition,
5972	const Stmt *Body) {
5973	// Potential constant expressions can contain calls to declared, but not yet
5974	// defined, constexpr functions.
5975	if (Info.checkingPotentialConstantExpression() && !Definition &&
5976	Declaration->isConstexpr())
5977	return false;
5978
5979	// Bail out if the function declaration itself is invalid. We will
5980	// have produced a relevant diagnostic while parsing it, so just
5981	// note the problematic sub-expression.
5982	if (Declaration->isInvalidDecl()) {
5983	Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5984	return false;
5985	}
5986
5987	// DR1872: An instantiated virtual constexpr function can't be called in a
5988	// constant expression (prior to C++20). We can still constant-fold such a
5989	// call.
5990	if (!Info.Ctx.getLangOpts().CPlusPlus20 && isa<CXXMethodDecl>(Declaration) &&
5991	cast<CXXMethodDecl>(Declaration)->isVirtual())
5992	Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call);
5993
5994	if (Definition && Definition->isInvalidDecl()) {
5995	Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
5996	return false;
5997	}
5998
5999	// Can we evaluate this function call?
6000	if (Definition && Body &&
6001	(Definition->isConstexpr() || (Info.CurrentCall->CanEvalMSConstexpr &&
6002	Definition->hasAttr<MSConstexprAttr>())))
6003	return true;
6004
6005	const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
6006	// Special note for the assert() macro, as the normal error message falsely
6007	// implies we cannot use an assertion during constant evaluation.
6008	if (CallLoc.isMacroID() && DiagDecl->getIdentifier()) {
6009	// FIXME: Instead of checking for an implementation-defined function,
6010	// check and evaluate the assert() macro.
6011	StringRef Name = DiagDecl->getName();
6012	bool AssertFailed =
6013	Name == "__assert_rtn" || Name == "__assert_fail" || Name == "_wassert";
6014	if (AssertFailed) {
6015	Info.FFDiag(CallLoc, diag::note_constexpr_assert_failed);
6016	return false;
6017	}
6018	}
6019
6020	if (Info.getLangOpts().CPlusPlus11) {
6021	// If this function is not constexpr because it is an inherited
6022	// non-constexpr constructor, diagnose that directly.
6023	auto *CD = dyn_cast<CXXConstructorDecl>(Val: DiagDecl);
6024	if (CD && CD->isInheritingConstructor()) {
6025	auto *Inherited = CD->getInheritedConstructor().getConstructor();
6026	if (!Inherited->isConstexpr())
6027	DiagDecl = CD = Inherited;
6028	}
6029
6030	// FIXME: If DiagDecl is an implicitly-declared special member function
6031	// or an inheriting constructor, we should be much more explicit about why
6032	// it's not constexpr.
6033	if (CD && CD->isInheritingConstructor())
6034	Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
6035	<< CD->getInheritedConstructor().getConstructor()->getParent();
6036	else
6037	Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
6038	<< DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
6039	Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
6040	} else {
6041	Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
6042	}
6043	return false;
6044	}
6045
6046	namespace {
6047	struct CheckDynamicTypeHandler {
6048	AccessKinds AccessKind;
6049	typedef bool result_type;
6050	bool failed() { return false; }
6051	bool found(APValue &Subobj, QualType SubobjType) { return true; }
6052	bool found(APSInt &Value, QualType SubobjType) { return true; }
6053	bool found(APFloat &Value, QualType SubobjType) { return true; }
6054	};
6055	} // end anonymous namespace
6056
6057	/// Check that we can access the notional vptr of an object / determine its
6058	/// dynamic type.
6059	static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This,
6060	AccessKinds AK, bool Polymorphic) {
6061	// We are not allowed to invoke a virtual function whose dynamic type
6062	// is constexpr-unknown, so stop early and let this fail later on if we
6063	// attempt to do so.
6064	// C++23 [expr.const]p5.6
6065	// an invocation of a virtual function ([class.virtual]) for an object whose
6066	// dynamic type is constexpr-unknown;
6067	if (This.allowConstexprUnknown())
6068	return true;
6069
6070	if (This.Designator.Invalid)
6071	return false;
6072
6073	CompleteObject Obj = findCompleteObject(Info, E, AK, LVal: This, LValType: QualType());
6074
6075	if (!Obj)
6076	return false;
6077
6078	if (!Obj.Value) {
6079	// The object is not usable in constant expressions, so we can't inspect
6080	// its value to see if it's in-lifetime or what the active union members
6081	// are. We can still check for a one-past-the-end lvalue.
6082	if (This.Designator.isOnePastTheEnd() ||
6083	This.Designator.isMostDerivedAnUnsizedArray()) {
6084	Info.FFDiag(E, This.Designator.isOnePastTheEnd()
6085	? diag::note_constexpr_access_past_end
6086	: diag::note_constexpr_access_unsized_array)
6087	<< AK;
6088	return false;
6089	} else if (Polymorphic) {
6090	// Conservatively refuse to perform a polymorphic operation if we would
6091	// not be able to read a notional 'vptr' value.
6092	APValue Val;
6093	This.moveInto(V&: Val);
6094	QualType StarThisType =
6095	Info.Ctx.getLValueReferenceType(T: This.Designator.getType(Info.Ctx));
6096	Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type)
6097	<< AK << Val.getAsString(Info.Ctx, StarThisType);
6098	return false;
6099	}
6100	return true;
6101	}
6102
6103	CheckDynamicTypeHandler Handler{.AccessKind: AK};
6104	return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
6105	}
6106
6107	/// Check that the pointee of the 'this' pointer in a member function call is
6108	/// either within its lifetime or in its period of construction or destruction.
6109	static bool
6110	checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E,
6111	const LValue &This,
6112	const CXXMethodDecl *NamedMember) {
6113	return checkDynamicType(
6114	Info, E, This,
6115	AK: isa<CXXDestructorDecl>(Val: NamedMember) ? AK_Destroy : AK_MemberCall, Polymorphic: false);
6116	}
6117
6118	struct DynamicType {
6119	/// The dynamic class type of the object.
6120	const CXXRecordDecl *Type;
6121	/// The corresponding path length in the lvalue.
6122	unsigned PathLength;
6123	};
6124
6125	static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator,
6126	unsigned PathLength) {
6127	assert(PathLength >= Designator.MostDerivedPathLength && PathLength <=
6128	Designator.Entries.size() && "invalid path length");
6129	return (PathLength == Designator.MostDerivedPathLength)
6130	? Designator.MostDerivedType->getAsCXXRecordDecl()
6131	: getAsBaseClass(E: Designator.Entries[PathLength - 1]);
6132	}
6133
6134	/// Determine the dynamic type of an object.
6135	static std::optional<DynamicType> ComputeDynamicType(EvalInfo &Info,
6136	const Expr *E,
6137	LValue &This,
6138	AccessKinds AK) {
6139	// If we don't have an lvalue denoting an object of class type, there is no
6140	// meaningful dynamic type. (We consider objects of non-class type to have no
6141	// dynamic type.)
6142	if (!checkDynamicType(Info, E, This, AK,
6143	Polymorphic: (AK == AK_TypeId
6144	? (E->getType()->isReferenceType() ? true : false)
6145	: true)))
6146	return std::nullopt;
6147
6148	if (This.Designator.Invalid)
6149	return std::nullopt;
6150
6151	// Refuse to compute a dynamic type in the presence of virtual bases. This
6152	// shouldn't happen other than in constant-folding situations, since literal
6153	// types can't have virtual bases.
6154	//
6155	// Note that consumers of DynamicType assume that the type has no virtual
6156	// bases, and will need modifications if this restriction is relaxed.
6157	const CXXRecordDecl *Class =
6158	This.Designator.MostDerivedType->getAsCXXRecordDecl();
6159	if (!Class || Class->getNumVBases()) {
6160	Info.FFDiag(E);
6161	return std::nullopt;
6162	}
6163
6164	// FIXME: For very deep class hierarchies, it might be beneficial to use a
6165	// binary search here instead. But the overwhelmingly common case is that
6166	// we're not in the middle of a constructor, so it probably doesn't matter
6167	// in practice.
6168	ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries;
6169	for (unsigned PathLength = This.Designator.MostDerivedPathLength;
6170	PathLength <= Path.size(); ++PathLength) {
6171	switch (Info.isEvaluatingCtorDtor(Base: This.getLValueBase(),
6172	Path: Path.slice(N: 0, M: PathLength))) {
6173	case ConstructionPhase::Bases:
6174	case ConstructionPhase::DestroyingBases:
6175	// We're constructing or destroying a base class. This is not the dynamic
6176	// type.
6177	break;
6178
6179	case ConstructionPhase::None:
6180	case ConstructionPhase::AfterBases:
6181	case ConstructionPhase::AfterFields:
6182	case ConstructionPhase::Destroying:
6183	// We've finished constructing the base classes and not yet started
6184	// destroying them again, so this is the dynamic type.
6185	return DynamicType{getBaseClassType(This.Designator, PathLength),
6186	PathLength};
6187	}
6188	}
6189
6190	// CWG issue 1517: we're constructing a base class of the object described by
6191	// 'This', so that object has not yet begun its period of construction and
6192	// any polymorphic operation on it results in undefined behavior.
6193	Info.FFDiag(E);
6194	return std::nullopt;
6195	}
6196
6197	/// Perform virtual dispatch.
6198	static const CXXMethodDecl *HandleVirtualDispatch(
6199	EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found,
6200	llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) {
6201	std::optional<DynamicType> DynType = ComputeDynamicType(
6202	Info, E, This,
6203	AK: isa<CXXDestructorDecl>(Val: Found) ? AK_Destroy : AK_MemberCall);
6204	if (!DynType)
6205	return nullptr;
6206
6207	// Find the final overrider. It must be declared in one of the classes on the
6208	// path from the dynamic type to the static type.
6209	// FIXME: If we ever allow literal types to have virtual base classes, that
6210	// won't be true.
6211	const CXXMethodDecl *Callee = Found;
6212	unsigned PathLength = DynType->PathLength;
6213	for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) {
6214	const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength);
6215	const CXXMethodDecl *Overrider =
6216	Found->getCorrespondingMethodDeclaredInClass(RD: Class, MayBeBase: false);
6217	if (Overrider) {
6218	Callee = Overrider;
6219	break;
6220	}
6221	}
6222
6223	// C++2a [class.abstract]p6:
6224	// the effect of making a virtual call to a pure virtual function [...] is
6225	// undefined
6226	if (Callee->isPureVirtual()) {
6227	Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee;
6228	Info.Note(Callee->getLocation(), diag::note_declared_at);
6229	return nullptr;
6230	}
6231
6232	// If necessary, walk the rest of the path to determine the sequence of
6233	// covariant adjustment steps to apply.
6234	if (!Info.Ctx.hasSameUnqualifiedType(T1: Callee->getReturnType(),
6235	T2: Found->getReturnType())) {
6236	CovariantAdjustmentPath.push_back(Elt: Callee->getReturnType());
6237	for (unsigned CovariantPathLength = PathLength + 1;
6238	CovariantPathLength != This.Designator.Entries.size();
6239	++CovariantPathLength) {
6240	const CXXRecordDecl *NextClass =
6241	getBaseClassType(This.Designator, CovariantPathLength);
6242	const CXXMethodDecl *Next =
6243	Found->getCorrespondingMethodDeclaredInClass(RD: NextClass, MayBeBase: false);
6244	if (Next && !Info.Ctx.hasSameUnqualifiedType(
6245	T1: Next->getReturnType(), T2: CovariantAdjustmentPath.back()))
6246	CovariantAdjustmentPath.push_back(Elt: Next->getReturnType());
6247	}
6248	if (!Info.Ctx.hasSameUnqualifiedType(T1: Found->getReturnType(),
6249	T2: CovariantAdjustmentPath.back()))
6250	CovariantAdjustmentPath.push_back(Elt: Found->getReturnType());
6251	}
6252
6253	// Perform 'this' adjustment.
6254	if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength))
6255	return nullptr;
6256
6257	return Callee;
6258	}
6259
6260	/// Perform the adjustment from a value returned by a virtual function to
6261	/// a value of the statically expected type, which may be a pointer or
6262	/// reference to a base class of the returned type.
6263	static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E,
6264	APValue &Result,
6265	ArrayRef<QualType> Path) {
6266	assert(Result.isLValue() &&
6267	"unexpected kind of APValue for covariant return");
6268	if (Result.isNullPointer())
6269	return true;
6270
6271	LValue LVal;
6272	LVal.setFrom(Ctx&: Info.Ctx, V: Result);
6273
6274	const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl();
6275	for (unsigned I = 1; I != Path.size(); ++I) {
6276	const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl();
6277	assert(OldClass && NewClass && "unexpected kind of covariant return");
6278	if (OldClass != NewClass &&
6279	!CastToBaseClass(Info, E, Result&: LVal, DerivedRD: OldClass, BaseRD: NewClass))
6280	return false;
6281	OldClass = NewClass;
6282	}
6283
6284	LVal.moveInto(V&: Result);
6285	return true;
6286	}
6287
6288	/// Determine whether \p Base, which is known to be a direct base class of
6289	/// \p Derived, is a public base class.
6290	static bool isBaseClassPublic(const CXXRecordDecl *Derived,
6291	const CXXRecordDecl *Base) {
6292	for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) {
6293	auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl();
6294	if (BaseClass && declaresSameEntity(BaseClass, Base))
6295	return BaseSpec.getAccessSpecifier() == AS_public;
6296	}
6297	llvm_unreachable("Base is not a direct base of Derived");
6298	}
6299
6300	/// Apply the given dynamic cast operation on the provided lvalue.
6301	///
6302	/// This implements the hard case of dynamic_cast, requiring a "runtime check"
6303	/// to find a suitable target subobject.
6304	static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E,
6305	LValue &Ptr) {
6306	// We can't do anything with a non-symbolic pointer value.
6307	SubobjectDesignator &D = Ptr.Designator;
6308	if (D.Invalid)
6309	return false;
6310
6311	// C++ [expr.dynamic.cast]p6:
6312	// If v is a null pointer value, the result is a null pointer value.
6313	if (Ptr.isNullPointer() && !E->isGLValue())
6314	return true;
6315
6316	// For all the other cases, we need the pointer to point to an object within
6317	// its lifetime / period of construction / destruction, and we need to know
6318	// its dynamic type.
6319	std::optional<DynamicType> DynType =
6320	ComputeDynamicType(Info, E, Ptr, AK_DynamicCast);
6321	if (!DynType)
6322	return false;
6323
6324	// C++ [expr.dynamic.cast]p7:
6325	// If T is "pointer to cv void", then the result is a pointer to the most
6326	// derived object
6327	if (E->getType()->isVoidPointerType())
6328	return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength);
6329
6330	const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl();
6331	assert(C && "dynamic_cast target is not void pointer nor class");
6332	CanQualType CQT = Info.Ctx.getCanonicalType(T: Info.Ctx.getRecordType(C));
6333
6334	auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) {
6335	// C++ [expr.dynamic.cast]p9:
6336	if (!E->isGLValue()) {
6337	// The value of a failed cast to pointer type is the null pointer value
6338	// of the required result type.
6339	Ptr.setNull(Ctx&: Info.Ctx, PointerTy: E->getType());
6340	return true;
6341	}
6342
6343	// A failed cast to reference type throws [...] std::bad_cast.
6344	unsigned DiagKind;
6345	if (!Paths && (declaresSameEntity(DynType->Type, C) ||
6346	DynType->Type->isDerivedFrom(Base: C)))
6347	DiagKind = 0;
6348	else if (!Paths || Paths->begin() == Paths->end())
6349	DiagKind = 1;
6350	else if (Paths->isAmbiguous(BaseType: CQT))
6351	DiagKind = 2;
6352	else {
6353	assert(Paths->front().Access != AS_public && "why did the cast fail?");
6354	DiagKind = 3;
6355	}
6356	Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed)
6357	<< DiagKind << Ptr.Designator.getType(Info.Ctx)
6358	<< Info.Ctx.getRecordType(DynType->Type)
6359	<< E->getType().getUnqualifiedType();
6360	return false;
6361	};
6362
6363	// Runtime check, phase 1:
6364	// Walk from the base subobject towards the derived object looking for the
6365	// target type.
6366	for (int PathLength = Ptr.Designator.Entries.size();
6367	PathLength >= (int)DynType->PathLength; --PathLength) {
6368	const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength);
6369	if (declaresSameEntity(Class, C))
6370	return CastToDerivedClass(Info, E, Ptr, Class, PathLength);
6371	// We can only walk across public inheritance edges.
6372	if (PathLength > (int)DynType->PathLength &&
6373	!isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1),
6374	Class))
6375	return RuntimeCheckFailed(nullptr);
6376	}
6377
6378	// Runtime check, phase 2:
6379	// Search the dynamic type for an unambiguous public base of type C.
6380	CXXBasePaths Paths(/*FindAmbiguities=*/true,
6381	/*RecordPaths=*/true, /*DetectVirtual=*/false);
6382	if (DynType->Type->isDerivedFrom(Base: C, Paths) && !Paths.isAmbiguous(BaseType: CQT) &&
6383	Paths.front().Access == AS_public) {
6384	// Downcast to the dynamic type...
6385	if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength))
6386	return false;
6387	// ... then upcast to the chosen base class subobject.
6388	for (CXXBasePathElement &Elem : Paths.front())
6389	if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base))
6390	return false;
6391	return true;
6392	}
6393
6394	// Otherwise, the runtime check fails.
6395	return RuntimeCheckFailed(&Paths);
6396	}
6397
6398	namespace {
6399	struct StartLifetimeOfUnionMemberHandler {
6400	EvalInfo &Info;
6401	const Expr *LHSExpr;
6402	const FieldDecl *Field;
6403	bool DuringInit;
6404	bool Failed = false;
6405	static const AccessKinds AccessKind = AK_Assign;
6406
6407	typedef bool result_type;
6408	bool failed() { return Failed; }
6409	bool found(APValue &Subobj, QualType SubobjType) {
6410	// We are supposed to perform no initialization but begin the lifetime of
6411	// the object. We interpret that as meaning to do what default
6412	// initialization of the object would do if all constructors involved were
6413	// trivial:
6414	// * All base, non-variant member, and array element subobjects' lifetimes
6415	// begin
6416	// * No variant members' lifetimes begin
6417	// * All scalar subobjects whose lifetimes begin have indeterminate values
6418	assert(SubobjType->isUnionType());
6419	if (declaresSameEntity(Subobj.getUnionField(), Field)) {
6420	// This union member is already active. If it's also in-lifetime, there's
6421	// nothing to do.
6422	if (Subobj.getUnionValue().hasValue())
6423	return true;
6424	} else if (DuringInit) {
6425	// We're currently in the process of initializing a different union
6426	// member. If we carried on, that initialization would attempt to
6427	// store to an inactive union member, resulting in undefined behavior.
6428	Info.FFDiag(LHSExpr,
6429	diag::note_constexpr_union_member_change_during_init);
6430	return false;
6431	}
6432	APValue Result;
6433	Failed = !handleDefaultInitValue(Field->getType(), Result);
6434	Subobj.setUnion(Field, Value: Result);
6435	return true;
6436	}
6437	bool found(APSInt &Value, QualType SubobjType) {
6438	llvm_unreachable("wrong value kind for union object");
6439	}
6440	bool found(APFloat &Value, QualType SubobjType) {
6441	llvm_unreachable("wrong value kind for union object");
6442	}
6443	};
6444	} // end anonymous namespace
6445
6446	const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind;
6447
6448	/// Handle a builtin simple-assignment or a call to a trivial assignment
6449	/// operator whose left-hand side might involve a union member access. If it
6450	/// does, implicitly start the lifetime of any accessed union elements per
6451	/// C++20 [class.union]5.
6452	static bool MaybeHandleUnionActiveMemberChange(EvalInfo &Info,
6453	const Expr *LHSExpr,
6454	const LValue &LHS) {
6455	if (LHS.InvalidBase || LHS.Designator.Invalid)
6456	return false;
6457
6458	llvm::SmallVector<std::pair<unsigned, const FieldDecl*>, 4> UnionPathLengths;
6459	// C++ [class.union]p5:
6460	// define the set S(E) of subexpressions of E as follows:
6461	unsigned PathLength = LHS.Designator.Entries.size();
6462	for (const Expr *E = LHSExpr; E != nullptr;) {
6463	// -- If E is of the form A.B, S(E) contains the elements of S(A)...
6464	if (auto *ME = dyn_cast<MemberExpr>(Val: E)) {
6465	auto *FD = dyn_cast<FieldDecl>(Val: ME->getMemberDecl());
6466	// Note that we can't implicitly start the lifetime of a reference,
6467	// so we don't need to proceed any further if we reach one.
6468	if (!FD || FD->getType()->isReferenceType())
6469	break;
6470
6471	// ... and also contains A.B if B names a union member ...
6472	if (FD->getParent()->isUnion()) {
6473	// ... of a non-class, non-array type, or of a class type with a
6474	// trivial default constructor that is not deleted, or an array of
6475	// such types.
6476	auto *RD =
6477	FD->getType()->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
6478	if (!RD || RD->hasTrivialDefaultConstructor())
6479	UnionPathLengths.push_back(Elt: {PathLength - 1, FD});
6480	}
6481
6482	E = ME->getBase();
6483	--PathLength;
6484	assert(declaresSameEntity(FD,
6485	LHS.Designator.Entries[PathLength]
6486	.getAsBaseOrMember().getPointer()));
6487
6488	// -- If E is of the form A[B] and is interpreted as a built-in array
6489	// subscripting operator, S(E) is [S(the array operand, if any)].
6490	} else if (auto *ASE = dyn_cast<ArraySubscriptExpr>(Val: E)) {
6491	// Step over an ArrayToPointerDecay implicit cast.
6492	auto *Base = ASE->getBase()->IgnoreImplicit();
6493	if (!Base->getType()->isArrayType())
6494	break;
6495
6496	E = Base;
6497	--PathLength;
6498
6499	} else if (auto *ICE = dyn_cast<ImplicitCastExpr>(Val: E)) {
6500	// Step over a derived-to-base conversion.
6501	E = ICE->getSubExpr();
6502	if (ICE->getCastKind() == CK_NoOp)
6503	continue;
6504	if (ICE->getCastKind() != CK_DerivedToBase &&
6505	ICE->getCastKind() != CK_UncheckedDerivedToBase)
6506	break;
6507	// Walk path backwards as we walk up from the base to the derived class.
6508	for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) {
6509	if (Elt->isVirtual()) {
6510	// A class with virtual base classes never has a trivial default
6511	// constructor, so S(E) is empty in this case.
6512	E = nullptr;
6513	break;
6514	}
6515
6516	--PathLength;
6517	assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(),
6518	LHS.Designator.Entries[PathLength]
6519	.getAsBaseOrMember().getPointer()));
6520	}
6521
6522	// -- Otherwise, S(E) is empty.
6523	} else {
6524	break;
6525	}
6526	}
6527
6528	// Common case: no unions' lifetimes are started.
6529	if (UnionPathLengths.empty())
6530	return true;
6531
6532	// if modification of X [would access an inactive union member], an object
6533	// of the type of X is implicitly created
6534	CompleteObject Obj =
6535	findCompleteObject(Info, E: LHSExpr, AK: AK_Assign, LVal: LHS, LValType: LHSExpr->getType());
6536	if (!Obj)
6537	return false;
6538	for (std::pair<unsigned, const FieldDecl *> LengthAndField :
6539	llvm::reverse(C&: UnionPathLengths)) {
6540	// Form a designator for the union object.
6541	SubobjectDesignator D = LHS.Designator;
6542	D.truncate(Ctx&: Info.Ctx, Base: LHS.Base, NewLength: LengthAndField.first);
6543
6544	bool DuringInit = Info.isEvaluatingCtorDtor(Base: LHS.Base, Path: D.Entries) ==
6545	ConstructionPhase::AfterBases;
6546	StartLifetimeOfUnionMemberHandler StartLifetime{
6547	.Info: Info, .LHSExpr: LHSExpr, .Field: LengthAndField.second, .DuringInit: DuringInit};
6548	if (!findSubobject(Info, E: LHSExpr, Obj, Sub: D, handler&: StartLifetime))
6549	return false;
6550	}
6551
6552	return true;
6553	}
6554
6555	static bool EvaluateCallArg(const ParmVarDecl *PVD, const Expr *Arg,
6556	CallRef Call, EvalInfo &Info, bool NonNull = false,
6557	APValue **EvaluatedArg = nullptr) {
6558	LValue LV;
6559	// Create the parameter slot and register its destruction. For a vararg
6560	// argument, create a temporary.
6561	// FIXME: For calling conventions that destroy parameters in the callee,
6562	// should we consider performing destruction when the function returns
6563	// instead?
6564	APValue &V = PVD ? Info.CurrentCall->createParam(Args: Call, PVD, LV)
6565	: Info.CurrentCall->createTemporary(Key: Arg, T: Arg->getType(),
6566	Scope: ScopeKind::Call, LV);
6567	if (!EvaluateInPlace(Result&: V, Info, This: LV, E: Arg))
6568	return false;
6569
6570	// Passing a null pointer to an __attribute__((nonnull)) parameter results in
6571	// undefined behavior, so is non-constant.
6572	if (NonNull && V.isLValue() && V.isNullPointer()) {
6573	Info.CCEDiag(Arg, diag::note_non_null_attribute_failed);
6574	return false;
6575	}
6576
6577	if (EvaluatedArg)
6578	*EvaluatedArg = &V;
6579
6580	return true;
6581	}
6582
6583	/// Evaluate the arguments to a function call.
6584	static bool EvaluateArgs(ArrayRef<const Expr *> Args, CallRef Call,
6585	EvalInfo &Info, const FunctionDecl *Callee,
6586	bool RightToLeft = false,
6587	LValue *ObjectArg = nullptr) {
6588	bool Success = true;
6589	llvm::SmallBitVector ForbiddenNullArgs;
6590	if (Callee->hasAttr<NonNullAttr>()) {
6591	ForbiddenNullArgs.resize(N: Args.size());
6592	for (const auto *Attr : Callee->specific_attrs<NonNullAttr>()) {
6593	if (!Attr->args_size()) {
6594	ForbiddenNullArgs.set();
6595	break;
6596	} else
6597	for (auto Idx : Attr->args()) {
6598	unsigned ASTIdx = Idx.getASTIndex();
6599	if (ASTIdx >= Args.size())
6600	continue;
6601	ForbiddenNullArgs[ASTIdx] = true;
6602	}
6603	}
6604	}
6605	for (unsigned I = 0; I < Args.size(); I++) {
6606	unsigned Idx = RightToLeft ? Args.size() - I - 1 : I;
6607	const ParmVarDecl *PVD =
6608	Idx < Callee->getNumParams() ? Callee->getParamDecl(i: Idx) : nullptr;
6609	bool NonNull = !ForbiddenNullArgs.empty() && ForbiddenNullArgs[Idx];
6610	APValue *That = nullptr;
6611	if (!EvaluateCallArg(PVD, Arg: Args[Idx], Call, Info, NonNull, EvaluatedArg: &That)) {
6612	// If we're checking for a potential constant expression, evaluate all
6613	// initializers even if some of them fail.
6614	if (!Info.noteFailure())
6615	return false;
6616	Success = false;
6617	}
6618	if (PVD && PVD->isExplicitObjectParameter() && That && That->isLValue())
6619	ObjectArg->setFrom(Ctx&: Info.Ctx, V: *That);
6620	}
6621	return Success;
6622	}
6623
6624	/// Perform a trivial copy from Param, which is the parameter of a copy or move
6625	/// constructor or assignment operator.
6626	static bool handleTrivialCopy(EvalInfo &Info, const ParmVarDecl *Param,
6627	const Expr *E, APValue &Result,
6628	bool CopyObjectRepresentation) {
6629	// Find the reference argument.
6630	CallStackFrame *Frame = Info.CurrentCall;
6631	APValue *RefValue = Info.getParamSlot(Call: Frame->Arguments, PVD: Param);
6632	if (!RefValue) {
6633	Info.FFDiag(E);
6634	return false;
6635	}
6636
6637	// Copy out the contents of the RHS object.
6638	LValue RefLValue;
6639	RefLValue.setFrom(Ctx&: Info.Ctx, V: *RefValue);
6640	return handleLValueToRValueConversion(
6641	Info, E, Param->getType().getNonReferenceType(), RefLValue, Result,
6642	CopyObjectRepresentation);
6643	}
6644
6645	/// Evaluate a function call.
6646	static bool HandleFunctionCall(SourceLocation CallLoc,
6647	const FunctionDecl *Callee,
6648	const LValue *ObjectArg, const Expr *E,
6649	ArrayRef<const Expr *> Args, CallRef Call,
6650	const Stmt *Body, EvalInfo &Info,
6651	APValue &Result, const LValue *ResultSlot) {
6652	if (!Info.CheckCallLimit(Loc: CallLoc))
6653	return false;
6654
6655	CallStackFrame Frame(Info, E->getSourceRange(), Callee, ObjectArg, E, Call);
6656
6657	// For a trivial copy or move assignment, perform an APValue copy. This is
6658	// essential for unions, where the operations performed by the assignment
6659	// operator cannot be represented as statements.
6660	//
6661	// Skip this for non-union classes with no fields; in that case, the defaulted
6662	// copy/move does not actually read the object.
6663	const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Val: Callee);
6664	if (MD && MD->isDefaulted() &&
6665	(MD->getParent()->isUnion() ||
6666	(MD->isTrivial() &&
6667	isReadByLvalueToRvalueConversion(RD: MD->getParent())))) {
6668	unsigned ExplicitOffset = MD->isExplicitObjectMemberFunction() ? 1 : 0;
6669	assert(ObjectArg &&
6670	(MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()));
6671	APValue RHSValue;
6672	if (!handleTrivialCopy(Info, MD->getParamDecl(0), Args[0], RHSValue,
6673	MD->getParent()->isUnion()))
6674	return false;
6675
6676	LValue Obj;
6677	if (!handleAssignment(Info, E: Args[ExplicitOffset], LVal: *ObjectArg,
6678	LValType: MD->getFunctionObjectParameterReferenceType(),
6679	Val&: RHSValue))
6680	return false;
6681	ObjectArg->moveInto(V&: Result);
6682	return true;
6683	} else if (MD && isLambdaCallOperator(MD)) {
6684	// We're in a lambda; determine the lambda capture field maps unless we're
6685	// just constexpr checking a lambda's call operator. constexpr checking is
6686	// done before the captures have been added to the closure object (unless
6687	// we're inferring constexpr-ness), so we don't have access to them in this
6688	// case. But since we don't need the captures to constexpr check, we can
6689	// just ignore them.
6690	if (!Info.checkingPotentialConstantExpression())
6691	MD->getParent()->getCaptureFields(Captures&: Frame.LambdaCaptureFields,
6692	ThisCapture&: Frame.LambdaThisCaptureField);
6693	}
6694
6695	StmtResult Ret = {.Value: Result, .Slot: ResultSlot};
6696	EvalStmtResult ESR = EvaluateStmt(Result&: Ret, Info, S: Body);
6697	if (ESR == ESR_Succeeded) {
6698	if (Callee->getReturnType()->isVoidType())
6699	return true;
6700	Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return);
6701	}
6702	return ESR == ESR_Returned;
6703	}
6704
6705	/// Evaluate a constructor call.
6706	static bool HandleConstructorCall(const Expr *E, const LValue &This,
6707	CallRef Call,
6708	const CXXConstructorDecl *Definition,
6709	EvalInfo &Info, APValue &Result) {
6710	SourceLocation CallLoc = E->getExprLoc();
6711	if (!Info.CheckCallLimit(Loc: CallLoc))
6712	return false;
6713
6714	const CXXRecordDecl *RD = Definition->getParent();
6715	if (RD->getNumVBases()) {
6716	Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
6717	return false;
6718	}
6719
6720	EvalInfo::EvaluatingConstructorRAII EvalObj(
6721	Info,
6722	ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
6723	RD->getNumBases());
6724	CallStackFrame Frame(Info, E->getSourceRange(), Definition, &This, E, Call);
6725
6726	// FIXME: Creating an APValue just to hold a nonexistent return value is
6727	// wasteful.
6728	APValue RetVal;
6729	StmtResult Ret = {.Value: RetVal, .Slot: nullptr};
6730
6731	// If it's a delegating constructor, delegate.
6732	if (Definition->isDelegatingConstructor()) {
6733	CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
6734	if ((*I)->getInit()->isValueDependent()) {
6735	if (!EvaluateDependentExpr(E: (*I)->getInit(), Info))
6736	return false;
6737	} else {
6738	FullExpressionRAII InitScope(Info);
6739	if (!EvaluateInPlace(Result, Info, This, E: (*I)->getInit()) ||
6740	!InitScope.destroy())
6741	return false;
6742	}
6743	return EvaluateStmt(Result&: Ret, Info, S: Definition->getBody()) != ESR_Failed;
6744	}
6745
6746	// For a trivial copy or move constructor, perform an APValue copy. This is
6747	// essential for unions (or classes with anonymous union members), where the
6748	// operations performed by the constructor cannot be represented by
6749	// ctor-initializers.
6750	//
6751	// Skip this for empty non-union classes; we should not perform an
6752	// lvalue-to-rvalue conversion on them because their copy constructor does not
6753	// actually read them.
6754	if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() &&
6755	(Definition->getParent()->isUnion() ||
6756	(Definition->isTrivial() &&
6757	isReadByLvalueToRvalueConversion(Definition->getParent())))) {
6758	return handleTrivialCopy(Info, Definition->getParamDecl(0), E, Result,
6759	Definition->getParent()->isUnion());
6760	}
6761
6762	// Reserve space for the struct members.
6763	if (!Result.hasValue()) {
6764	if (!RD->isUnion())
6765	Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
6766	std::distance(RD->field_begin(), RD->field_end()));
6767	else
6768	// A union starts with no active member.
6769	Result = APValue((const FieldDecl*)nullptr);
6770	}
6771
6772	if (RD->isInvalidDecl()) return false;
6773	const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
6774
6775	// A scope for temporaries lifetime-extended by reference members.
6776	BlockScopeRAII LifetimeExtendedScope(Info);
6777
6778	bool Success = true;
6779	unsigned BasesSeen = 0;
6780	#ifndef NDEBUG
6781	CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin();
6782	#endif
6783	CXXRecordDecl::field_iterator FieldIt = RD->field_begin();
6784	auto SkipToField = [&](FieldDecl *FD, bool Indirect) {
6785	// We might be initializing the same field again if this is an indirect
6786	// field initialization.
6787	if (FieldIt == RD->field_end() ||
6788	FieldIt->getFieldIndex() > FD->getFieldIndex()) {
6789	assert(Indirect && "fields out of order?");
6790	return;
6791	}
6792
6793	// Default-initialize any fields with no explicit initializer.
6794	for (; !declaresSameEntity(*FieldIt, FD); ++FieldIt) {
6795	assert(FieldIt != RD->field_end() && "missing field?");
6796	if (!FieldIt->isUnnamedBitField())
6797	Success &= handleDefaultInitValue(
6798	FieldIt->getType(),
6799	Result.getStructField(i: FieldIt->getFieldIndex()));
6800	}
6801	++FieldIt;
6802	};
6803	for (const auto *I : Definition->inits()) {
6804	LValue Subobject = This;
6805	LValue SubobjectParent = This;
6806	APValue *Value = &Result;
6807
6808	// Determine the subobject to initialize.
6809	FieldDecl *FD = nullptr;
6810	if (I->isBaseInitializer()) {
6811	QualType BaseType(I->getBaseClass(), 0);
6812	#ifndef NDEBUG
6813	// Non-virtual base classes are initialized in the order in the class
6814	// definition. We have already checked for virtual base classes.
6815	assert(!BaseIt->isVirtual() && "virtual base for literal type");
6816	assert(Info.Ctx.hasSameUnqualifiedType(BaseIt->getType(), BaseType) &&
6817	"base class initializers not in expected order");
6818	++BaseIt;
6819	#endif
6820	if (!HandleLValueDirectBase(Info, E: I->getInit(), Obj&: Subobject, Derived: RD,
6821	Base: BaseType->getAsCXXRecordDecl(), RL: &Layout))
6822	return false;
6823	Value = &Result.getStructBase(i: BasesSeen++);
6824	} else if ((FD = I->getMember())) {
6825	if (!HandleLValueMember(Info, E: I->getInit(), LVal&: Subobject, FD, RL: &Layout))
6826	return false;
6827	if (RD->isUnion()) {
6828	Result = APValue(FD);
6829	Value = &Result.getUnionValue();
6830	} else {
6831	SkipToField(FD, false);
6832	Value = &Result.getStructField(i: FD->getFieldIndex());
6833	}
6834	} else if (IndirectFieldDecl *IFD = I->getIndirectMember()) {
6835	// Walk the indirect field decl's chain to find the object to initialize,
6836	// and make sure we've initialized every step along it.
6837	auto IndirectFieldChain = IFD->chain();
6838	for (auto *C : IndirectFieldChain) {
6839	FD = cast<FieldDecl>(Val: C);
6840	CXXRecordDecl *CD = cast<CXXRecordDecl>(Val: FD->getParent());
6841	// Switch the union field if it differs. This happens if we had
6842	// preceding zero-initialization, and we're now initializing a union
6843	// subobject other than the first.
6844	// FIXME: In this case, the values of the other subobjects are
6845	// specified, since zero-initialization sets all padding bits to zero.
6846	if (!Value->hasValue() ||
6847	(Value->isUnion() &&
6848	!declaresSameEntity(Value->getUnionField(), FD))) {
6849	if (CD->isUnion())
6850	*Value = APValue(FD);
6851	else
6852	// FIXME: This immediately starts the lifetime of all members of
6853	// an anonymous struct. It would be preferable to strictly start
6854	// member lifetime in initialization order.
6855	Success &=
6856	handleDefaultInitValue(T: Info.Ctx.getRecordType(CD), Result&: *Value);
6857	}
6858	// Store Subobject as its parent before updating it for the last element
6859	// in the chain.
6860	if (C == IndirectFieldChain.back())
6861	SubobjectParent = Subobject;
6862	if (!HandleLValueMember(Info, E: I->getInit(), LVal&: Subobject, FD))
6863	return false;
6864	if (CD->isUnion())
6865	Value = &Value->getUnionValue();
6866	else {
6867	if (C == IndirectFieldChain.front() && !RD->isUnion())
6868	SkipToField(FD, true);
6869	Value = &Value->getStructField(i: FD->getFieldIndex());
6870	}
6871	}
6872	} else {
6873	llvm_unreachable("unknown base initializer kind");
6874	}
6875
6876	// Need to override This for implicit field initializers as in this case
6877	// This refers to innermost anonymous struct/union containing initializer,
6878	// not to currently constructed class.
6879	const Expr *Init = I->getInit();
6880	if (Init->isValueDependent()) {
6881	if (!EvaluateDependentExpr(E: Init, Info))
6882	return false;
6883	} else {
6884	ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent,
6885	isa<CXXDefaultInitExpr>(Val: Init));
6886	FullExpressionRAII InitScope(Info);
6887	if (!EvaluateInPlace(Result&: *Value, Info, This: Subobject, E: Init) ||
6888	(FD && FD->isBitField() &&
6889	!truncateBitfieldValue(Info, E: Init, Value&: *Value, FD))) {
6890	// If we're checking for a potential constant expression, evaluate all
6891	// initializers even if some of them fail.
6892	if (!Info.noteFailure())
6893	return false;
6894	Success = false;
6895	}
6896	}
6897
6898	// This is the point at which the dynamic type of the object becomes this
6899	// class type.
6900	if (I->isBaseInitializer() && BasesSeen == RD->getNumBases())
6901	EvalObj.finishedConstructingBases();
6902	}
6903
6904	// Default-initialize any remaining fields.
6905	if (!RD->isUnion()) {
6906	for (; FieldIt != RD->field_end(); ++FieldIt) {
6907	if (!FieldIt->isUnnamedBitField())
6908	Success &= handleDefaultInitValue(
6909	FieldIt->getType(),
6910	Result.getStructField(i: FieldIt->getFieldIndex()));
6911	}
6912	}
6913
6914	EvalObj.finishedConstructingFields();
6915
6916	return Success &&
6917	EvaluateStmt(Result&: Ret, Info, S: Definition->getBody()) != ESR_Failed &&
6918	LifetimeExtendedScope.destroy();
6919	}
6920
6921	static bool HandleConstructorCall(const Expr *E, const LValue &This,
6922	ArrayRef<const Expr*> Args,
6923	const CXXConstructorDecl *Definition,
6924	EvalInfo &Info, APValue &Result) {
6925	CallScopeRAII CallScope(Info);
6926	CallRef Call = Info.CurrentCall->createCall(Definition);
6927	if (!EvaluateArgs(Args, Call, Info, Definition))
6928	return false;
6929
6930	return HandleConstructorCall(E, This, Call, Definition, Info, Result) &&
6931	CallScope.destroy();
6932	}
6933
6934	static bool HandleDestructionImpl(EvalInfo &Info, SourceRange CallRange,
6935	const LValue &This, APValue &Value,
6936	QualType T) {
6937	// Objects can only be destroyed while they're within their lifetimes.
6938	// FIXME: We have no representation for whether an object of type nullptr_t
6939	// is in its lifetime; it usually doesn't matter. Perhaps we should model it
6940	// as indeterminate instead?
6941	if (Value.isAbsent() && !T->isNullPtrType()) {
6942	APValue Printable;
6943	This.moveInto(V&: Printable);
6944	Info.FFDiag(CallRange.getBegin(),
6945	diag::note_constexpr_destroy_out_of_lifetime)
6946	<< Printable.getAsString(Info.Ctx, Info.Ctx.getLValueReferenceType(T));
6947	return false;
6948	}
6949
6950	// Invent an expression for location purposes.
6951	// FIXME: We shouldn't need to do this.
6952	OpaqueValueExpr LocE(CallRange.getBegin(), Info.Ctx.IntTy, VK_PRValue);
6953
6954	// For arrays, destroy elements right-to-left.
6955	if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T)) {
6956	uint64_t Size = CAT->getZExtSize();
6957	QualType ElemT = CAT->getElementType();
6958
6959	if (!CheckArraySize(Info, CAT, CallLoc: CallRange.getBegin()))
6960	return false;
6961
6962	LValue ElemLV = This;
6963	ElemLV.addArray(Info, &LocE, CAT);
6964	if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, Size))
6965	return false;
6966
6967	// Ensure that we have actual array elements available to destroy; the
6968	// destructors might mutate the value, so we can't run them on the array
6969	// filler.
6970	if (Size && Size > Value.getArrayInitializedElts())
6971	expandArray(Array&: Value, Index: Value.getArraySize() - 1);
6972
6973	// The size of the array might have been reduced by
6974	// a placement new.
6975	for (Size = Value.getArraySize(); Size != 0; --Size) {
6976	APValue &Elem = Value.getArrayInitializedElt(I: Size - 1);
6977	if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, -1) ||
6978	!HandleDestructionImpl(Info, CallRange, This: ElemLV, Value&: Elem, T: ElemT))
6979	return false;
6980	}
6981
6982	// End the lifetime of this array now.
6983	Value = APValue();
6984	return true;
6985	}
6986
6987	const CXXRecordDecl *RD = T->getAsCXXRecordDecl();
6988	if (!RD) {
6989	if (T.isDestructedType()) {
6990	Info.FFDiag(CallRange.getBegin(),
6991	diag::note_constexpr_unsupported_destruction)
6992	<< T;
6993	return false;
6994	}
6995
6996	Value = APValue();
6997	return true;
6998	}
6999
7000	if (RD->getNumVBases()) {
7001	Info.FFDiag(CallRange.getBegin(), diag::note_constexpr_virtual_base) << RD;
7002	return false;
7003	}
7004
7005	const CXXDestructorDecl *DD = RD->getDestructor();
7006	if (!DD && !RD->hasTrivialDestructor()) {
7007	Info.FFDiag(Loc: CallRange.getBegin());
7008	return false;
7009	}
7010
7011	if (!DD || DD->isTrivial() ||
7012	(RD->isAnonymousStructOrUnion() && RD->isUnion())) {
7013	// A trivial destructor just ends the lifetime of the object. Check for
7014	// this case before checking for a body, because we might not bother
7015	// building a body for a trivial destructor. Note that it doesn't matter
7016	// whether the destructor is constexpr in this case; all trivial
7017	// destructors are constexpr.
7018	//
7019	// If an anonymous union would be destroyed, some enclosing destructor must
7020	// have been explicitly defined, and the anonymous union destruction should
7021	// have no effect.
7022	Value = APValue();
7023	return true;
7024	}
7025
7026	if (!Info.CheckCallLimit(Loc: CallRange.getBegin()))
7027	return false;
7028
7029	const FunctionDecl *Definition = nullptr;
7030	const Stmt *Body = DD->getBody(Definition);
7031
7032	if (!CheckConstexprFunction(Info, CallRange.getBegin(), DD, Definition, Body))
7033	return false;
7034
7035	CallStackFrame Frame(Info, CallRange, Definition, &This, /*CallExpr=*/nullptr,
7036	CallRef());
7037
7038	// We're now in the period of destruction of this object.
7039	unsigned BasesLeft = RD->getNumBases();
7040	EvalInfo::EvaluatingDestructorRAII EvalObj(
7041	Info,
7042	ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries});
7043	if (!EvalObj.DidInsert) {
7044	// C++2a [class.dtor]p19:
7045	// the behavior is undefined if the destructor is invoked for an object
7046	// whose lifetime has ended
7047	// (Note that formally the lifetime ends when the period of destruction
7048	// begins, even though certain uses of the object remain valid until the
7049	// period of destruction ends.)
7050	Info.FFDiag(CallRange.getBegin(), diag::note_constexpr_double_destroy);
7051	return false;
7052	}
7053
7054	// FIXME: Creating an APValue just to hold a nonexistent return value is
7055	// wasteful.
7056	APValue RetVal;
7057	StmtResult Ret = {.Value: RetVal, .Slot: nullptr};
7058	if (EvaluateStmt(Result&: Ret, Info, S: Definition->getBody()) == ESR_Failed)
7059	return false;
7060
7061	// A union destructor does not implicitly destroy its members.
7062	if (RD->isUnion())
7063	return true;
7064
7065	const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
7066
7067	// We don't have a good way to iterate fields in reverse, so collect all the
7068	// fields first and then walk them backwards.
7069	SmallVector<FieldDecl*, 16> Fields(RD->fields());
7070	for (const FieldDecl *FD : llvm::reverse(Fields)) {
7071	if (FD->isUnnamedBitField())
7072	continue;
7073
7074	LValue Subobject = This;
7075	if (!HandleLValueMember(Info, &LocE, Subobject, FD, &Layout))
7076	return false;
7077
7078	APValue *SubobjectValue = &Value.getStructField(FD->getFieldIndex());
7079	if (!HandleDestructionImpl(Info, CallRange, Subobject, *SubobjectValue,
7080	FD->getType()))
7081	return false;
7082	}
7083
7084	if (BasesLeft != 0)
7085	EvalObj.startedDestroyingBases();
7086
7087	// Destroy base classes in reverse order.
7088	for (const CXXBaseSpecifier &Base : llvm::reverse(C: RD->bases())) {
7089	--BasesLeft;
7090
7091	QualType BaseType = Base.getType();
7092	LValue Subobject = This;
7093	if (!HandleLValueDirectBase(Info, &LocE, Subobject, RD,
7094	BaseType->getAsCXXRecordDecl(), &Layout))
7095	return false;
7096
7097	APValue *SubobjectValue = &Value.getStructBase(i: BasesLeft);
7098	if (!HandleDestructionImpl(Info, CallRange, This: Subobject, Value&: *SubobjectValue,
7099	T: BaseType))
7100	return false;
7101	}
7102	assert(BasesLeft == 0 && "NumBases was wrong?");
7103
7104	// The period of destruction ends now. The object is gone.
7105	Value = APValue();
7106	return true;
7107	}
7108
7109	namespace {
7110	struct DestroyObjectHandler {
7111	EvalInfo &Info;
7112	const Expr *E;
7113	const LValue &This;
7114	const AccessKinds AccessKind;
7115
7116	typedef bool result_type;
7117	bool failed() { return false; }
7118	bool found(APValue &Subobj, QualType SubobjType) {
7119	return HandleDestructionImpl(Info, E->getSourceRange(), This, Subobj,
7120	SubobjType);
7121	}
7122	bool found(APSInt &Value, QualType SubobjType) {
7123	Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem);
7124	return false;
7125	}
7126	bool found(APFloat &Value, QualType SubobjType) {
7127	Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem);
7128	return false;
7129	}
7130	};
7131	}
7132
7133	/// Perform a destructor or pseudo-destructor call on the given object, which
7134	/// might in general not be a complete object.
7135	static bool HandleDestruction(EvalInfo &Info, const Expr *E,
7136	const LValue &This, QualType ThisType) {
7137	CompleteObject Obj = findCompleteObject(Info, E, AK: AK_Destroy, LVal: This, LValType: ThisType);
7138	DestroyObjectHandler Handler = {.Info: Info, .E: E, .This: This, .AccessKind: AK_Destroy};
7139	return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
7140	}
7141
7142	/// Destroy and end the lifetime of the given complete object.
7143	static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
7144	APValue::LValueBase LVBase, APValue &Value,
7145	QualType T) {
7146	// If we've had an unmodeled side-effect, we can't rely on mutable state
7147	// (such as the object we're about to destroy) being correct.
7148	if (Info.EvalStatus.HasSideEffects)
7149	return false;
7150
7151	LValue LV;
7152	LV.set(B: {LVBase});
7153	return HandleDestructionImpl(Info, CallRange: Loc, This: LV, Value, T);
7154	}
7155
7156	/// Perform a call to 'operator new' or to `__builtin_operator_new'.
7157	static bool HandleOperatorNewCall(EvalInfo &Info, const CallExpr *E,
7158	LValue &Result) {
7159	if (Info.checkingPotentialConstantExpression() ||
7160	Info.SpeculativeEvaluationDepth)
7161	return false;
7162
7163	// This is permitted only within a call to std::allocator<T>::allocate.
7164	auto Caller = Info.getStdAllocatorCaller(FnName: "allocate");
7165	if (!Caller) {
7166	Info.FFDiag(E->getExprLoc(), Info.getLangOpts().CPlusPlus20
7167	? diag::note_constexpr_new_untyped
7168	: diag::note_constexpr_new);
7169	return false;
7170	}
7171
7172	QualType ElemType = Caller.ElemType;
7173	if (ElemType->isIncompleteType() || ElemType->isFunctionType()) {
7174	Info.FFDiag(E->getExprLoc(),
7175	diag::note_constexpr_new_not_complete_object_type)
7176	<< (ElemType->isIncompleteType() ? 0 : 1) << ElemType;
7177	return false;
7178	}
7179
7180	APSInt ByteSize;
7181	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: ByteSize, Info))
7182	return false;
7183	bool IsNothrow = false;
7184	for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I) {
7185	EvaluateIgnoredValue(Info, E: E->getArg(Arg: I));
7186	IsNothrow |= E->getType()->isNothrowT();
7187	}
7188
7189	CharUnits ElemSize;
7190	if (!HandleSizeof(Info, E->getExprLoc(), ElemType, ElemSize))
7191	return false;
7192	APInt Size, Remainder;
7193	APInt ElemSizeAP(ByteSize.getBitWidth(), ElemSize.getQuantity());
7194	APInt::udivrem(LHS: ByteSize, RHS: ElemSizeAP, Quotient&: Size, Remainder);
7195	if (Remainder != 0) {
7196	// This likely indicates a bug in the implementation of 'std::allocator'.
7197	Info.FFDiag(E->getExprLoc(), diag::note_constexpr_operator_new_bad_size)
7198	<< ByteSize << APSInt(ElemSizeAP, true) << ElemType;
7199	return false;
7200	}
7201
7202	if (!Info.CheckArraySize(Loc: E->getBeginLoc(), BitWidth: ByteSize.getActiveBits(),
7203	ElemCount: Size.getZExtValue(), /*Diag=*/!IsNothrow)) {
7204	if (IsNothrow) {
7205	Result.setNull(Ctx&: Info.Ctx, PointerTy: E->getType());
7206	return true;
7207	}
7208	return false;
7209	}
7210
7211	QualType AllocType = Info.Ctx.getConstantArrayType(
7212	EltTy: ElemType, ArySize: Size, SizeExpr: nullptr, ASM: ArraySizeModifier::Normal, IndexTypeQuals: 0);
7213	APValue *Val = Info.createHeapAlloc(E: Caller.Call, T: AllocType, LV&: Result);
7214	*Val = APValue(APValue::UninitArray(), 0, Size.getZExtValue());
7215	Result.addArray(Info, E, cast<ConstantArrayType>(Val&: AllocType));
7216	return true;
7217	}
7218
7219	static bool hasVirtualDestructor(QualType T) {
7220	if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
7221	if (CXXDestructorDecl *DD = RD->getDestructor())
7222	return DD->isVirtual();
7223	return false;
7224	}
7225
7226	static const FunctionDecl *getVirtualOperatorDelete(QualType T) {
7227	if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
7228	if (CXXDestructorDecl *DD = RD->getDestructor())
7229	return DD->isVirtual() ? DD->getOperatorDelete() : nullptr;
7230	return nullptr;
7231	}
7232
7233	/// Check that the given object is a suitable pointer to a heap allocation that
7234	/// still exists and is of the right kind for the purpose of a deletion.
7235	///
7236	/// On success, returns the heap allocation to deallocate. On failure, produces
7237	/// a diagnostic and returns std::nullopt.
7238	static std::optional<DynAlloc *> CheckDeleteKind(EvalInfo &Info, const Expr *E,
7239	const LValue &Pointer,
7240	DynAlloc::Kind DeallocKind) {
7241	auto PointerAsString = [&] {
7242	return Pointer.toString(Info.Ctx, Info.Ctx.VoidPtrTy);
7243	};
7244
7245	DynamicAllocLValue DA = Pointer.Base.dyn_cast<DynamicAllocLValue>();
7246	if (!DA) {
7247	Info.FFDiag(E, diag::note_constexpr_delete_not_heap_alloc)
7248	<< PointerAsString();
7249	if (Pointer.Base)
7250	NoteLValueLocation(Info, Base: Pointer.Base);
7251	return std::nullopt;
7252	}
7253
7254	std::optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA);
7255	if (!Alloc) {
7256	Info.FFDiag(E, diag::note_constexpr_double_delete);
7257	return std::nullopt;
7258	}
7259
7260	if (DeallocKind != (*Alloc)->getKind()) {
7261	QualType AllocType = Pointer.Base.getDynamicAllocType();
7262	Info.FFDiag(E, diag::note_constexpr_new_delete_mismatch)
7263	<< DeallocKind << (*Alloc)->getKind() << AllocType;
7264	NoteLValueLocation(Info, Base: Pointer.Base);
7265	return std::nullopt;
7266	}
7267
7268	bool Subobject = false;
7269	if (DeallocKind == DynAlloc::New) {
7270	Subobject = Pointer.Designator.MostDerivedPathLength != 0 ||
7271	Pointer.Designator.isOnePastTheEnd();
7272	} else {
7273	Subobject = Pointer.Designator.Entries.size() != 1 ||
7274	Pointer.Designator.Entries[0].getAsArrayIndex() != 0;
7275	}
7276	if (Subobject) {
7277	Info.FFDiag(E, diag::note_constexpr_delete_subobject)
7278	<< PointerAsString() << Pointer.Designator.isOnePastTheEnd();
7279	return std::nullopt;
7280	}
7281
7282	return Alloc;
7283	}
7284
7285	// Perform a call to 'operator delete' or '__builtin_operator_delete'.
7286	static bool HandleOperatorDeleteCall(EvalInfo &Info, const CallExpr *E) {
7287	if (Info.checkingPotentialConstantExpression() ||
7288	Info.SpeculativeEvaluationDepth)
7289	return false;
7290
7291	// This is permitted only within a call to std::allocator<T>::deallocate.
7292	if (!Info.getStdAllocatorCaller(FnName: "deallocate")) {
7293	Info.FFDiag(E->getExprLoc());
7294	return true;
7295	}
7296
7297	LValue Pointer;
7298	if (!EvaluatePointer(E: E->getArg(Arg: 0), Result&: Pointer, Info))
7299	return false;
7300	for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I)
7301	EvaluateIgnoredValue(Info, E: E->getArg(Arg: I));
7302
7303	if (Pointer.Designator.Invalid)
7304	return false;
7305
7306	// Deleting a null pointer would have no effect, but it's not permitted by
7307	// std::allocator<T>::deallocate's contract.
7308	if (Pointer.isNullPointer()) {
7309	Info.CCEDiag(E->getExprLoc(), diag::note_constexpr_deallocate_null);
7310	return true;
7311	}
7312
7313	if (!CheckDeleteKind(Info, E, Pointer, DynAlloc::StdAllocator))
7314	return false;
7315
7316	Info.HeapAllocs.erase(x: Pointer.Base.get<DynamicAllocLValue>());
7317	return true;
7318	}
7319
7320	//===----------------------------------------------------------------------===//
7321	// Generic Evaluation
7322	//===----------------------------------------------------------------------===//
7323	namespace {
7324
7325	class BitCastBuffer {
7326	// FIXME: We're going to need bit-level granularity when we support
7327	// bit-fields.
7328	// FIXME: Its possible under the C++ standard for 'char' to not be 8 bits, but
7329	// we don't support a host or target where that is the case. Still, we should
7330	// use a more generic type in case we ever do.
7331	SmallVector<std::optional<unsigned char>, 32> Bytes;
7332
7333	static_assert(std::numeric_limits<unsigned char>::digits >= 8,
7334	"Need at least 8 bit unsigned char");
7335
7336	bool TargetIsLittleEndian;
7337
7338	public:
7339	BitCastBuffer(CharUnits Width, bool TargetIsLittleEndian)
7340	: Bytes(Width.getQuantity()),
7341	TargetIsLittleEndian(TargetIsLittleEndian) {}
7342
7343	[[nodiscard]] bool readObject(CharUnits Offset, CharUnits Width,
7344	SmallVectorImpl<unsigned char> &Output) const {
7345	for (CharUnits I = Offset, E = Offset + Width; I != E; ++I) {
7346	// If a byte of an integer is uninitialized, then the whole integer is
7347	// uninitialized.
7348	if (!Bytes[I.getQuantity()])
7349	return false;
7350	Output.push_back(Elt: *Bytes[I.getQuantity()]);
7351	}
7352	if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian)
7353	std::reverse(first: Output.begin(), last: Output.end());
7354	return true;
7355	}
7356
7357	void writeObject(CharUnits Offset, SmallVectorImpl<unsigned char> &Input) {
7358	if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian)
7359	std::reverse(first: Input.begin(), last: Input.end());
7360
7361	size_t Index = 0;
7362	for (unsigned char Byte : Input) {
7363	assert(!Bytes[Offset.getQuantity() + Index] && "overwriting a byte?");
7364	Bytes[Offset.getQuantity() + Index] = Byte;
7365	++Index;
7366	}
7367	}
7368
7369	size_t size() { return Bytes.size(); }
7370	};
7371
7372	/// Traverse an APValue to produce an BitCastBuffer, emulating how the current
7373	/// target would represent the value at runtime.
7374	class APValueToBufferConverter {
7375	EvalInfo &Info;
7376	BitCastBuffer Buffer;
7377	const CastExpr *BCE;
7378
7379	APValueToBufferConverter(EvalInfo &Info, CharUnits ObjectWidth,
7380	const CastExpr *BCE)
7381	: Info(Info),
7382	Buffer(ObjectWidth, Info.Ctx.getTargetInfo().isLittleEndian()),
7383	BCE(BCE) {}
7384
7385	bool visit(const APValue &Val, QualType Ty) {
7386	return visit(Val, Ty, Offset: CharUnits::fromQuantity(Quantity: 0));
7387	}
7388
7389	// Write out Val with type Ty into Buffer starting at Offset.
7390	bool visit(const APValue &Val, QualType Ty, CharUnits Offset) {
7391	assert((size_t)Offset.getQuantity() <= Buffer.size());
7392
7393	// As a special case, nullptr_t has an indeterminate value.
7394	if (Ty->isNullPtrType())
7395	return true;
7396
7397	// Dig through Src to find the byte at SrcOffset.
7398	switch (Val.getKind()) {
7399	case APValue::Indeterminate:
7400	case APValue::None:
7401	return true;
7402
7403	case APValue::Int:
7404	return visitInt(Val: Val.getInt(), Ty, Offset);
7405	case APValue::Float:
7406	return visitFloat(Val: Val.getFloat(), Ty, Offset);
7407	case APValue::Array:
7408	return visitArray(Val, Ty, Offset);
7409	case APValue::Struct:
7410	return visitRecord(Val, Ty, Offset);
7411	case APValue::Vector:
7412	return visitVector(Val, Ty, Offset);
7413
7414	case APValue::ComplexInt:
7415	case APValue::ComplexFloat:
7416	return visitComplex(Val, Ty, Offset);
7417	case APValue::FixedPoint:
7418	// FIXME: We should support these.
7419
7420	case APValue::Union:
7421	case APValue::MemberPointer:
7422	case APValue::AddrLabelDiff: {
7423	Info.FFDiag(BCE->getBeginLoc(),
7424	diag::note_constexpr_bit_cast_unsupported_type)
7425	<< Ty;
7426	return false;
7427	}
7428
7429	case APValue::LValue:
7430	llvm_unreachable("LValue subobject in bit_cast?");
7431	}
7432	llvm_unreachable("Unhandled APValue::ValueKind");
7433	}
7434
7435	bool visitRecord(const APValue &Val, QualType Ty, CharUnits Offset) {
7436	const RecordDecl *RD = Ty->getAsRecordDecl();
7437	const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(D: RD);
7438
7439	// Visit the base classes.
7440	if (auto *CXXRD = dyn_cast<CXXRecordDecl>(Val: RD)) {
7441	for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) {
7442	const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I];
7443	CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
7444	const APValue &Base = Val.getStructBase(i: I);
7445
7446	// Can happen in error cases.
7447	if (!Base.isStruct())
7448	return false;
7449
7450	if (!visitRecord(Val: Base, Ty: BS.getType(),
7451	Offset: Layout.getBaseClassOffset(Base: BaseDecl) + Offset))
7452	return false;
7453	}
7454	}
7455
7456	// Visit the fields.
7457	unsigned FieldIdx = 0;
7458	for (FieldDecl *FD : RD->fields()) {
7459	if (FD->isBitField()) {
7460	Info.FFDiag(BCE->getBeginLoc(),
7461	diag::note_constexpr_bit_cast_unsupported_bitfield);
7462	return false;
7463	}
7464
7465	uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldNo: FieldIdx);
7466
7467	assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0 &&
7468	"only bit-fields can have sub-char alignment");
7469	CharUnits FieldOffset =
7470	Info.Ctx.toCharUnitsFromBits(BitSize: FieldOffsetBits) + Offset;
7471	QualType FieldTy = FD->getType();
7472	if (!visit(Val: Val.getStructField(i: FieldIdx), Ty: FieldTy, Offset: FieldOffset))
7473	return false;
7474	++FieldIdx;
7475	}
7476
7477	return true;
7478	}
7479
7480	bool visitArray(const APValue &Val, QualType Ty, CharUnits Offset) {
7481	const auto *CAT =
7482	dyn_cast_or_null<ConstantArrayType>(Ty->getAsArrayTypeUnsafe());
7483	if (!CAT)
7484	return false;
7485
7486	CharUnits ElemWidth = Info.Ctx.getTypeSizeInChars(CAT->getElementType());
7487	unsigned NumInitializedElts = Val.getArrayInitializedElts();
7488	unsigned ArraySize = Val.getArraySize();
7489	// First, initialize the initialized elements.
7490	for (unsigned I = 0; I != NumInitializedElts; ++I) {
7491	const APValue &SubObj = Val.getArrayInitializedElt(I);
7492	if (!visit(SubObj, CAT->getElementType(), Offset + I * ElemWidth))
7493	return false;
7494	}
7495
7496	// Next, initialize the rest of the array using the filler.
7497	if (Val.hasArrayFiller()) {
7498	const APValue &Filler = Val.getArrayFiller();
7499	for (unsigned I = NumInitializedElts; I != ArraySize; ++I) {
7500	if (!visit(Filler, CAT->getElementType(), Offset + I * ElemWidth))
7501	return false;
7502	}
7503	}
7504
7505	return true;
7506	}
7507
7508	bool visitComplex(const APValue &Val, QualType Ty, CharUnits Offset) {
7509	const ComplexType *ComplexTy = Ty->castAs<ComplexType>();
7510	QualType EltTy = ComplexTy->getElementType();
7511	CharUnits EltSizeChars = Info.Ctx.getTypeSizeInChars(T: EltTy);
7512	bool IsInt = Val.isComplexInt();
7513
7514	if (IsInt) {
7515	if (!visitInt(Val: Val.getComplexIntReal(), Ty: EltTy,
7516	Offset: Offset + (0 * EltSizeChars)))
7517	return false;
7518	if (!visitInt(Val: Val.getComplexIntImag(), Ty: EltTy,
7519	Offset: Offset + (1 * EltSizeChars)))
7520	return false;
7521	} else {
7522	if (!visitFloat(Val: Val.getComplexFloatReal(), Ty: EltTy,
7523	Offset: Offset + (0 * EltSizeChars)))
7524	return false;
7525	if (!visitFloat(Val: Val.getComplexFloatImag(), Ty: EltTy,
7526	Offset: Offset + (1 * EltSizeChars)))
7527	return false;
7528	}
7529
7530	return true;
7531	}
7532
7533	bool visitVector(const APValue &Val, QualType Ty, CharUnits Offset) {
7534	const VectorType *VTy = Ty->castAs<VectorType>();
7535	QualType EltTy = VTy->getElementType();
7536	unsigned NElts = VTy->getNumElements();
7537
7538	if (VTy->isPackedVectorBoolType(Info.Ctx)) {
7539	// Special handling for OpenCL bool vectors:
7540	// Since these vectors are stored as packed bits, but we can't write
7541	// individual bits to the BitCastBuffer, we'll buffer all of the elements
7542	// together into an appropriately sized APInt and write them all out at
7543	// once. Because we don't accept vectors where NElts * EltSize isn't a
7544	// multiple of the char size, there will be no padding space, so we don't
7545	// have to worry about writing data which should have been left
7546	// uninitialized.
7547	bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
7548
7549	llvm::APInt Res = llvm::APInt::getZero(numBits: NElts);
7550	for (unsigned I = 0; I < NElts; ++I) {
7551	const llvm::APSInt &EltAsInt = Val.getVectorElt(I).getInt();
7552	assert(EltAsInt.isUnsigned() && EltAsInt.getBitWidth() == 1 &&
7553	"bool vector element must be 1-bit unsigned integer!");
7554
7555	Res.insertBits(SubBits: EltAsInt, bitPosition: BigEndian ? (NElts - I - 1) : I);
7556	}
7557
7558	SmallVector<uint8_t, 8> Bytes(NElts / 8);
7559	llvm::StoreIntToMemory(IntVal: Res, Dst: &*Bytes.begin(), StoreBytes: NElts / 8);
7560	Buffer.writeObject(Offset, Input&: Bytes);
7561	} else {
7562	// Iterate over each of the elements and write them out to the buffer at
7563	// the appropriate offset.
7564	CharUnits EltSizeChars = Info.Ctx.getTypeSizeInChars(T: EltTy);
7565	for (unsigned I = 0; I < NElts; ++I) {
7566	if (!visit(Val: Val.getVectorElt(I), Ty: EltTy, Offset: Offset + I * EltSizeChars))
7567	return false;
7568	}
7569	}
7570
7571	return true;
7572	}
7573
7574	bool visitInt(const APSInt &Val, QualType Ty, CharUnits Offset) {
7575	APSInt AdjustedVal = Val;
7576	unsigned Width = AdjustedVal.getBitWidth();
7577	if (Ty->isBooleanType()) {
7578	Width = Info.Ctx.getTypeSize(T: Ty);
7579	AdjustedVal = AdjustedVal.extend(width: Width);
7580	}
7581
7582	SmallVector<uint8_t, 8> Bytes(Width / 8);
7583	llvm::StoreIntToMemory(IntVal: AdjustedVal, Dst: &*Bytes.begin(), StoreBytes: Width / 8);
7584	Buffer.writeObject(Offset, Input&: Bytes);
7585	return true;
7586	}
7587
7588	bool visitFloat(const APFloat &Val, QualType Ty, CharUnits Offset) {
7589	APSInt AsInt(Val.bitcastToAPInt());
7590	return visitInt(Val: AsInt, Ty, Offset);
7591	}
7592
7593	public:
7594	static std::optional<BitCastBuffer>
7595	convert(EvalInfo &Info, const APValue &Src, const CastExpr *BCE) {
7596	CharUnits DstSize = Info.Ctx.getTypeSizeInChars(BCE->getType());
7597	APValueToBufferConverter Converter(Info, DstSize, BCE);
7598	if (!Converter.visit(Val: Src, Ty: BCE->getSubExpr()->getType()))
7599	return std::nullopt;
7600	return Converter.Buffer;
7601	}
7602	};
7603
7604	/// Write an BitCastBuffer into an APValue.
7605	class BufferToAPValueConverter {
7606	EvalInfo &Info;
7607	const BitCastBuffer &Buffer;
7608	const CastExpr *BCE;
7609
7610	BufferToAPValueConverter(EvalInfo &Info, const BitCastBuffer &Buffer,
7611	const CastExpr *BCE)
7612	: Info(Info), Buffer(Buffer), BCE(BCE) {}
7613
7614	// Emit an unsupported bit_cast type error. Sema refuses to build a bit_cast
7615	// with an invalid type, so anything left is a deficiency on our part (FIXME).
7616	// Ideally this will be unreachable.
7617	std::nullopt_t unsupportedType(QualType Ty) {
7618	Info.FFDiag(BCE->getBeginLoc(),
7619	diag::note_constexpr_bit_cast_unsupported_type)
7620	<< Ty;
7621	return std::nullopt;
7622	}
7623
7624	std::nullopt_t unrepresentableValue(QualType Ty, const APSInt &Val) {
7625	Info.FFDiag(BCE->getBeginLoc(),
7626	diag::note_constexpr_bit_cast_unrepresentable_value)
7627	<< Ty << toString(Val, /*Radix=*/10);
7628	return std::nullopt;
7629	}
7630
7631	std::optional<APValue> visit(const BuiltinType *T, CharUnits Offset,
7632	const EnumType *EnumSugar = nullptr) {
7633	if (T->isNullPtrType()) {
7634	uint64_t NullValue = Info.Ctx.getTargetNullPointerValue(QT: QualType(T, 0));
7635	return APValue((Expr *)nullptr,
7636	/*Offset=*/CharUnits::fromQuantity(Quantity: NullValue),
7637	APValue::NoLValuePath{}, /*IsNullPtr=*/true);
7638	}
7639
7640	CharUnits SizeOf = Info.Ctx.getTypeSizeInChars(T);
7641
7642	// Work around floating point types that contain unused padding bytes. This
7643	// is really just `long double` on x86, which is the only fundamental type
7644	// with padding bytes.
7645	if (T->isRealFloatingType()) {
7646	const llvm::fltSemantics &Semantics =
7647	Info.Ctx.getFloatTypeSemantics(T: QualType(T, 0));
7648	unsigned NumBits = llvm::APFloatBase::getSizeInBits(Sem: Semantics);
7649	assert(NumBits % 8 == 0);
7650	CharUnits NumBytes = CharUnits::fromQuantity(Quantity: NumBits / 8);
7651	if (NumBytes != SizeOf)
7652	SizeOf = NumBytes;
7653	}
7654
7655	SmallVector<uint8_t, 8> Bytes;
7656	if (!Buffer.readObject(Offset, Width: SizeOf, Output&: Bytes)) {
7657	// If this is std::byte or unsigned char, then its okay to store an
7658	// indeterminate value.
7659	bool IsStdByte = EnumSugar && EnumSugar->isStdByteType();
7660	bool IsUChar =
7661	!EnumSugar && (T->isSpecificBuiltinType(BuiltinType::UChar) ||
7662	T->isSpecificBuiltinType(BuiltinType::Char_U));
7663	if (!IsStdByte && !IsUChar) {
7664	QualType DisplayType(EnumSugar ? (const Type *)EnumSugar : T, 0);
7665	Info.FFDiag(BCE->getExprLoc(),
7666	diag::note_constexpr_bit_cast_indet_dest)
7667	<< DisplayType << Info.Ctx.getLangOpts().CharIsSigned;
7668	return std::nullopt;
7669	}
7670
7671	return APValue::IndeterminateValue();
7672	}
7673
7674	APSInt Val(SizeOf.getQuantity() * Info.Ctx.getCharWidth(), true);
7675	llvm::LoadIntFromMemory(IntVal&: Val, Src: &*Bytes.begin(), LoadBytes: Bytes.size());
7676
7677	if (T->isIntegralOrEnumerationType()) {
7678	Val.setIsSigned(T->isSignedIntegerOrEnumerationType());
7679
7680	unsigned IntWidth = Info.Ctx.getIntWidth(T: QualType(T, 0));
7681	if (IntWidth != Val.getBitWidth()) {
7682	APSInt Truncated = Val.trunc(width: IntWidth);
7683	if (Truncated.extend(width: Val.getBitWidth()) != Val)
7684	return unrepresentableValue(Ty: QualType(T, 0), Val);
7685	Val = Truncated;
7686	}
7687
7688	return APValue(Val);
7689	}
7690
7691	if (T->isRealFloatingType()) {
7692	const llvm::fltSemantics &Semantics =
7693	Info.Ctx.getFloatTypeSemantics(T: QualType(T, 0));
7694	return APValue(APFloat(Semantics, Val));
7695	}
7696
7697	return unsupportedType(Ty: QualType(T, 0));
7698	}
7699
7700	std::optional<APValue> visit(const RecordType *RTy, CharUnits Offset) {
7701	const RecordDecl *RD = RTy->getAsRecordDecl();
7702	const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(D: RD);
7703
7704	unsigned NumBases = 0;
7705	if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD))
7706	NumBases = CXXRD->getNumBases();
7707
7708	APValue ResultVal(APValue::UninitStruct(), NumBases,
7709	std::distance(RD->field_begin(), RD->field_end()));
7710
7711	// Visit the base classes.
7712	if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
7713	for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) {
7714	const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I];
7715	CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
7716
7717	std::optional<APValue> SubObj = visitType(
7718	BS.getType(), Layout.getBaseClassOffset(BaseDecl) + Offset);
7719	if (!SubObj)
7720	return std::nullopt;
7721	ResultVal.getStructBase(i: I) = *SubObj;
7722	}
7723	}
7724
7725	// Visit the fields.
7726	unsigned FieldIdx = 0;
7727	for (FieldDecl *FD : RD->fields()) {
7728	// FIXME: We don't currently support bit-fields. A lot of the logic for
7729	// this is in CodeGen, so we need to factor it around.
7730	if (FD->isBitField()) {
7731	Info.FFDiag(BCE->getBeginLoc(),
7732	diag::note_constexpr_bit_cast_unsupported_bitfield);
7733	return std::nullopt;
7734	}
7735
7736	uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx);
7737	assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0);
7738
7739	CharUnits FieldOffset =
7740	CharUnits::fromQuantity(FieldOffsetBits / Info.Ctx.getCharWidth()) +
7741	Offset;
7742	QualType FieldTy = FD->getType();
7743	std::optional<APValue> SubObj = visitType(FieldTy, FieldOffset);
7744	if (!SubObj)
7745	return std::nullopt;
7746	ResultVal.getStructField(FieldIdx) = *SubObj;
7747	++FieldIdx;
7748	}
7749
7750	return ResultVal;
7751	}
7752
7753	std::optional<APValue> visit(const EnumType *Ty, CharUnits Offset) {
7754	QualType RepresentationType = Ty->getDecl()->getIntegerType();
7755	assert(!RepresentationType.isNull() &&
7756	"enum forward decl should be caught by Sema");
7757	const auto *AsBuiltin =
7758	RepresentationType.getCanonicalType()->castAs<BuiltinType>();
7759	// Recurse into the underlying type. Treat std::byte transparently as
7760	// unsigned char.
7761	return visit(AsBuiltin, Offset, /*EnumTy=*/Ty);
7762	}
7763
7764	std::optional<APValue> visit(const ConstantArrayType *Ty, CharUnits Offset) {
7765	size_t Size = Ty->getLimitedSize();
7766	CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(Ty->getElementType());
7767
7768	APValue ArrayValue(APValue::UninitArray(), Size, Size);
7769	for (size_t I = 0; I != Size; ++I) {
7770	std::optional<APValue> ElementValue =
7771	visitType(Ty->getElementType(), Offset + I * ElementWidth);
7772	if (!ElementValue)
7773	return std::nullopt;
7774	ArrayValue.getArrayInitializedElt(I) = std::move(*ElementValue);
7775	}
7776
7777	return ArrayValue;
7778	}
7779
7780	std::optional<APValue> visit(const ComplexType *Ty, CharUnits Offset) {
7781	QualType ElementType = Ty->getElementType();
7782	CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(T: ElementType);
7783	bool IsInt = ElementType->isIntegerType();
7784
7785	std::optional<APValue> Values[2];
7786	for (unsigned I = 0; I != 2; ++I) {
7787	Values[I] = visitType(Ty->getElementType(), Offset + I * ElementWidth);
7788	if (!Values[I])
7789	return std::nullopt;
7790	}
7791
7792	if (IsInt)
7793	return APValue(Values[0]->getInt(), Values[1]->getInt());
7794	return APValue(Values[0]->getFloat(), Values[1]->getFloat());
7795	}
7796
7797	std::optional<APValue> visit(const VectorType *VTy, CharUnits Offset) {
7798	QualType EltTy = VTy->getElementType();
7799	unsigned NElts = VTy->getNumElements();
7800	unsigned EltSize =
7801	VTy->isPackedVectorBoolType(Info.Ctx) ? 1 : Info.Ctx.getTypeSize(T: EltTy);
7802
7803	SmallVector<APValue, 4> Elts;
7804	Elts.reserve(N: NElts);
7805	if (VTy->isPackedVectorBoolType(Info.Ctx)) {
7806	// Special handling for OpenCL bool vectors:
7807	// Since these vectors are stored as packed bits, but we can't read
7808	// individual bits from the BitCastBuffer, we'll buffer all of the
7809	// elements together into an appropriately sized APInt and write them all
7810	// out at once. Because we don't accept vectors where NElts * EltSize
7811	// isn't a multiple of the char size, there will be no padding space, so
7812	// we don't have to worry about reading any padding data which didn't
7813	// actually need to be accessed.
7814	bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
7815
7816	SmallVector<uint8_t, 8> Bytes;
7817	Bytes.reserve(N: NElts / 8);
7818	if (!Buffer.readObject(Offset, Width: CharUnits::fromQuantity(Quantity: NElts / 8), Output&: Bytes))
7819	return std::nullopt;
7820
7821	APSInt SValInt(NElts, true);
7822	llvm::LoadIntFromMemory(IntVal&: SValInt, Src: &*Bytes.begin(), LoadBytes: Bytes.size());
7823
7824	for (unsigned I = 0; I < NElts; ++I) {
7825	llvm::APInt Elt =
7826	SValInt.extractBits(numBits: 1, bitPosition: (BigEndian ? NElts - I - 1 : I) * EltSize);
7827	Elts.emplace_back(
7828	APSInt(std::move(Elt), !EltTy->isSignedIntegerType()));
7829	}
7830	} else {
7831	// Iterate over each of the elements and read them from the buffer at
7832	// the appropriate offset.
7833	CharUnits EltSizeChars = Info.Ctx.getTypeSizeInChars(T: EltTy);
7834	for (unsigned I = 0; I < NElts; ++I) {
7835	std::optional<APValue> EltValue =
7836	visitType(EltTy, Offset + I * EltSizeChars);
7837	if (!EltValue)
7838	return std::nullopt;
7839	Elts.push_back(std::move(*EltValue));
7840	}
7841	}
7842
7843	return APValue(Elts.data(), Elts.size());
7844	}
7845
7846	std::optional<APValue> visit(const Type *Ty, CharUnits Offset) {
7847	return unsupportedType(Ty: QualType(Ty, 0));
7848	}
7849
7850	std::optional<APValue> visitType(QualType Ty, CharUnits Offset) {
7851	QualType Can = Ty.getCanonicalType();
7852
7853	switch (Can->getTypeClass()) {
7854	#define TYPE(Class, Base) \
7855	case Type::Class: \
7856	return visit(cast<Class##Type>(Can.getTypePtr()), Offset);
7857	#define ABSTRACT_TYPE(Class, Base)
7858	#define NON_CANONICAL_TYPE(Class, Base) \
7859	case Type::Class: \
7860	llvm_unreachable("non-canonical type should be impossible!");
7861	#define DEPENDENT_TYPE(Class, Base) \
7862	case Type::Class: \
7863	llvm_unreachable( \
7864	"dependent types aren't supported in the constant evaluator!");
7865	#define NON_CANONICAL_UNLESS_DEPENDENT(Class, Base) \
7866	case Type::Class: \
7867	llvm_unreachable("either dependent or not canonical!");
7868	#include "clang/AST/TypeNodes.inc"
7869	}
7870	llvm_unreachable("Unhandled Type::TypeClass");
7871	}
7872
7873	public:
7874	// Pull out a full value of type DstType.
7875	static std::optional<APValue> convert(EvalInfo &Info, BitCastBuffer &Buffer,
7876	const CastExpr *BCE) {
7877	BufferToAPValueConverter Converter(Info, Buffer, BCE);
7878	return Converter.visitType(BCE->getType(), CharUnits::fromQuantity(Quantity: 0));
7879	}
7880	};
7881
7882	static bool checkBitCastConstexprEligibilityType(SourceLocation Loc,
7883	QualType Ty, EvalInfo *Info,
7884	const ASTContext &Ctx,
7885	bool CheckingDest) {
7886	Ty = Ty.getCanonicalType();
7887
7888	auto diag = [&](int Reason) {
7889	if (Info)
7890	Info->FFDiag(Loc, diag::note_constexpr_bit_cast_invalid_type)
7891	<< CheckingDest << (Reason == 4) << Reason;
7892	return false;
7893	};
7894	auto note = [&](int Construct, QualType NoteTy, SourceLocation NoteLoc) {
7895	if (Info)
7896	Info->Note(NoteLoc, diag::note_constexpr_bit_cast_invalid_subtype)
7897	<< NoteTy << Construct << Ty;
7898	return false;
7899	};
7900
7901	if (Ty->isUnionType())
7902	return diag(0);
7903	if (Ty->isPointerType())
7904	return diag(1);
7905	if (Ty->isMemberPointerType())
7906	return diag(2);
7907	if (Ty.isVolatileQualified())
7908	return diag(3);
7909
7910	if (RecordDecl *Record = Ty->getAsRecordDecl()) {
7911	if (auto *CXXRD = dyn_cast<CXXRecordDecl>(Record)) {
7912	for (CXXBaseSpecifier &BS : CXXRD->bases())
7913	if (!checkBitCastConstexprEligibilityType(Loc, BS.getType(), Info, Ctx,
7914	CheckingDest))
7915	return note(1, BS.getType(), BS.getBeginLoc());
7916	}
7917	for (FieldDecl *FD : Record->fields()) {
7918	if (FD->getType()->isReferenceType())
7919	return diag(4);
7920	if (!checkBitCastConstexprEligibilityType(Loc, FD->getType(), Info, Ctx,
7921	CheckingDest))
7922	return note(0, FD->getType(), FD->getBeginLoc());
7923	}
7924	}
7925
7926	if (Ty->isArrayType() &&
7927	!checkBitCastConstexprEligibilityType(Loc, Ty: Ctx.getBaseElementType(QT: Ty),
7928	Info, Ctx, CheckingDest))
7929	return false;
7930
7931	if (const auto *VTy = Ty->getAs<VectorType>()) {
7932	QualType EltTy = VTy->getElementType();
7933	unsigned NElts = VTy->getNumElements();
7934	unsigned EltSize =
7935	VTy->isPackedVectorBoolType(Ctx) ? 1 : Ctx.getTypeSize(T: EltTy);
7936
7937	if ((NElts * EltSize) % Ctx.getCharWidth() != 0) {
7938	// The vector's size in bits is not a multiple of the target's byte size,
7939	// so its layout is unspecified. For now, we'll simply treat these cases
7940	// as unsupported (this should only be possible with OpenCL bool vectors
7941	// whose element count isn't a multiple of the byte size).
7942	Info->FFDiag(Loc, diag::note_constexpr_bit_cast_invalid_vector)
7943	<< QualType(VTy, 0) << EltSize << NElts << Ctx.getCharWidth();
7944	return false;
7945	}
7946
7947	if (EltTy->isRealFloatingType() &&
7948	&Ctx.getFloatTypeSemantics(T: EltTy) == &APFloat::x87DoubleExtended()) {
7949	// The layout for x86_fp80 vectors seems to be handled very inconsistently
7950	// by both clang and LLVM, so for now we won't allow bit_casts involving
7951	// it in a constexpr context.
7952	Info->FFDiag(Loc, diag::note_constexpr_bit_cast_unsupported_type)
7953	<< EltTy;
7954	return false;
7955	}
7956	}
7957
7958	return true;
7959	}
7960
7961	static bool checkBitCastConstexprEligibility(EvalInfo *Info,
7962	const ASTContext &Ctx,
7963	const CastExpr *BCE) {
7964	bool DestOK = checkBitCastConstexprEligibilityType(
7965	BCE->getBeginLoc(), BCE->getType(), Info, Ctx, true);
7966	bool SourceOK = DestOK && checkBitCastConstexprEligibilityType(
7967	BCE->getBeginLoc(),
7968	BCE->getSubExpr()->getType(), Info, Ctx, false);
7969	return SourceOK;
7970	}
7971
7972	static bool handleRValueToRValueBitCast(EvalInfo &Info, APValue &DestValue,
7973	const APValue &SourceRValue,
7974	const CastExpr *BCE) {
7975	assert(CHAR_BIT == 8 && Info.Ctx.getTargetInfo().getCharWidth() == 8 &&
7976	"no host or target supports non 8-bit chars");
7977
7978	if (!checkBitCastConstexprEligibility(Info: &Info, Ctx: Info.Ctx, BCE))
7979	return false;
7980
7981	// Read out SourceValue into a char buffer.
7982	std::optional<BitCastBuffer> Buffer =
7983	APValueToBufferConverter::convert(Info, Src: SourceRValue, BCE);
7984	if (!Buffer)
7985	return false;
7986
7987	// Write out the buffer into a new APValue.
7988	std::optional<APValue> MaybeDestValue =
7989	BufferToAPValueConverter::convert(Info, *Buffer, BCE);
7990	if (!MaybeDestValue)
7991	return false;
7992
7993	DestValue = std::move(*MaybeDestValue);
7994	return true;
7995	}
7996
7997	static bool handleLValueToRValueBitCast(EvalInfo &Info, APValue &DestValue,
7998	APValue &SourceValue,
7999	const CastExpr *BCE) {
8000	assert(CHAR_BIT == 8 && Info.Ctx.getTargetInfo().getCharWidth() == 8 &&
8001	"no host or target supports non 8-bit chars");
8002	assert(SourceValue.isLValue() &&
8003	"LValueToRValueBitcast requires an lvalue operand!");
8004
8005	LValue SourceLValue;
8006	APValue SourceRValue;
8007	SourceLValue.setFrom(Ctx&: Info.Ctx, V: SourceValue);
8008	if (!handleLValueToRValueConversion(
8009	Info, BCE, BCE->getSubExpr()->getType().withConst(), SourceLValue,
8010	SourceRValue, /*WantObjectRepresentation=*/true))
8011	return false;
8012
8013	return handleRValueToRValueBitCast(Info, DestValue, SourceRValue, BCE);
8014	}
8015
8016	template <class Derived>
8017	class ExprEvaluatorBase
8018	: public ConstStmtVisitor<Derived, bool> {
8019	private:
8020	Derived &getDerived() { return static_cast<Derived&>(*this); }
8021	bool DerivedSuccess(const APValue &V, const Expr *E) {
8022	return getDerived().Success(V, E);
8023	}
8024	bool DerivedZeroInitialization(const Expr *E) {
8025	return getDerived().ZeroInitialization(E);
8026	}
8027
8028	// Check whether a conditional operator with a non-constant condition is a
8029	// potential constant expression. If neither arm is a potential constant
8030	// expression, then the conditional operator is not either.
8031	template<typename ConditionalOperator>
8032	void CheckPotentialConstantConditional(const ConditionalOperator *E) {
8033	assert(Info.checkingPotentialConstantExpression());
8034
8035	// Speculatively evaluate both arms.
8036	SmallVector<PartialDiagnosticAt, 8> Diag;
8037	{
8038	SpeculativeEvaluationRAII Speculate(Info, &Diag);
8039	StmtVisitorTy::Visit(E->getFalseExpr());
8040	if (Diag.empty())
8041	return;
8042	}
8043
8044	{
8045	SpeculativeEvaluationRAII Speculate(Info, &Diag);
8046	Diag.clear();
8047	StmtVisitorTy::Visit(E->getTrueExpr());
8048	if (Diag.empty())
8049	return;
8050	}
8051
8052	Error(E, diag::note_constexpr_conditional_never_const);
8053	}
8054
8055
8056	template<typename ConditionalOperator>
8057	bool HandleConditionalOperator(const ConditionalOperator *E) {
8058	bool BoolResult;
8059	if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) {
8060	if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) {
8061	CheckPotentialConstantConditional(E);
8062	return false;
8063	}
8064	if (Info.noteFailure()) {
8065	StmtVisitorTy::Visit(E->getTrueExpr());
8066	StmtVisitorTy::Visit(E->getFalseExpr());
8067	}
8068	return false;
8069	}
8070
8071	Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
8072	return StmtVisitorTy::Visit(EvalExpr);
8073	}
8074
8075	protected:
8076	EvalInfo &Info;
8077	typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy;
8078	typedef ExprEvaluatorBase ExprEvaluatorBaseTy;
8079
8080	OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
8081	return Info.CCEDiag(E, DiagId: D);
8082	}
8083
8084	bool ZeroInitialization(const Expr *E) { return Error(E); }
8085
8086	bool IsConstantEvaluatedBuiltinCall(const CallExpr *E) {
8087	unsigned BuiltinOp = E->getBuiltinCallee();
8088	return BuiltinOp != 0 &&
8089	Info.Ctx.BuiltinInfo.isConstantEvaluated(ID: BuiltinOp);
8090	}
8091
8092	public:
8093	ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {}
8094
8095	EvalInfo &getEvalInfo() { return Info; }
8096
8097	/// Report an evaluation error. This should only be called when an error is
8098	/// first discovered. When propagating an error, just return false.
8099	bool Error(const Expr *E, diag::kind D) {
8100	Info.FFDiag(E, DiagId: D) << E->getSourceRange();
8101	return false;
8102	}
8103	bool Error(const Expr *E) {
8104	return Error(E, diag::note_invalid_subexpr_in_const_expr);
8105	}
8106
8107	bool VisitStmt(const Stmt *) {
8108	llvm_unreachable("Expression evaluator should not be called on stmts");
8109	}
8110	bool VisitExpr(const Expr *E) {
8111	return Error(E);
8112	}
8113
8114	bool VisitEmbedExpr(const EmbedExpr *E) {
8115	const auto It = E->begin();
8116	return StmtVisitorTy::Visit(*It);
8117	}
8118
8119	bool VisitPredefinedExpr(const PredefinedExpr *E) {
8120	return StmtVisitorTy::Visit(E->getFunctionName());
8121	}
8122	bool VisitConstantExpr(const ConstantExpr *E) {
8123	if (E->hasAPValueResult())
8124	return DerivedSuccess(V: E->getAPValueResult(), E);
8125
8126	return StmtVisitorTy::Visit(E->getSubExpr());
8127	}
8128
8129	bool VisitParenExpr(const ParenExpr *E)
8130	{ return StmtVisitorTy::Visit(E->getSubExpr()); }
8131	bool VisitUnaryExtension(const UnaryOperator *E)
8132	{ return StmtVisitorTy::Visit(E->getSubExpr()); }
8133	bool VisitUnaryPlus(const UnaryOperator *E)
8134	{ return StmtVisitorTy::Visit(E->getSubExpr()); }
8135	bool VisitChooseExpr(const ChooseExpr *E)
8136	{ return StmtVisitorTy::Visit(E->getChosenSubExpr()); }
8137	bool VisitGenericSelectionExpr(const GenericSelectionExpr *E)
8138	{ return StmtVisitorTy::Visit(E->getResultExpr()); }
8139	bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E)
8140	{ return StmtVisitorTy::Visit(E->getReplacement()); }
8141	bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) {
8142	TempVersionRAII RAII(*Info.CurrentCall);
8143	SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope);
8144	return StmtVisitorTy::Visit(E->getExpr());
8145	}
8146	bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) {
8147	TempVersionRAII RAII(*Info.CurrentCall);
8148	// The initializer may not have been parsed yet, or might be erroneous.
8149	if (!E->getExpr())
8150	return Error(E);
8151	SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope);
8152	return StmtVisitorTy::Visit(E->getExpr());
8153	}
8154
8155	bool VisitExprWithCleanups(const ExprWithCleanups *E) {
8156	FullExpressionRAII Scope(Info);
8157	return StmtVisitorTy::Visit(E->getSubExpr()) && Scope.destroy();
8158	}
8159
8160	// Temporaries are registered when created, so we don't care about
8161	// CXXBindTemporaryExpr.
8162	bool VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr *E) {
8163	return StmtVisitorTy::Visit(E->getSubExpr());
8164	}
8165
8166	bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) {
8167	CCEDiag(E, diag::note_constexpr_invalid_cast)
8168	<< diag::ConstexprInvalidCastKind::Reinterpret;
8169	return static_cast<Derived*>(this)->VisitCastExpr(E);
8170	}
8171	bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) {
8172	if (!Info.Ctx.getLangOpts().CPlusPlus20)
8173	CCEDiag(E, diag::note_constexpr_invalid_cast)
8174	<< diag::ConstexprInvalidCastKind::Dynamic;
8175	return static_cast<Derived*>(this)->VisitCastExpr(E);
8176	}
8177	bool VisitBuiltinBitCastExpr(const BuiltinBitCastExpr *E) {
8178	return static_cast<Derived*>(this)->VisitCastExpr(E);
8179	}
8180
8181	bool VisitBinaryOperator(const BinaryOperator *E) {
8182	switch (E->getOpcode()) {
8183	default:
8184	return Error(E);
8185
8186	case BO_Comma:
8187	VisitIgnoredValue(E: E->getLHS());
8188	return StmtVisitorTy::Visit(E->getRHS());
8189
8190	case BO_PtrMemD:
8191	case BO_PtrMemI: {
8192	LValue Obj;
8193	if (!HandleMemberPointerAccess(Info, BO: E, LV&: Obj))
8194	return false;
8195	APValue Result;
8196	if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result))
8197	return false;
8198	return DerivedSuccess(V: Result, E);
8199	}
8200	}
8201	}
8202
8203	bool VisitCXXRewrittenBinaryOperator(const CXXRewrittenBinaryOperator *E) {
8204	return StmtVisitorTy::Visit(E->getSemanticForm());
8205	}
8206
8207	bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) {
8208	// Evaluate and cache the common expression. We treat it as a temporary,
8209	// even though it's not quite the same thing.
8210	LValue CommonLV;
8211	if (!Evaluate(Result&: Info.CurrentCall->createTemporary(
8212	E->getOpaqueValue(),
8213	getStorageType(Info.Ctx, E->getOpaqueValue()),
8214	ScopeKind::FullExpression, CommonLV),
8215	Info, E: E->getCommon()))
8216	return false;
8217
8218	return HandleConditionalOperator(E);
8219	}
8220
8221	bool VisitConditionalOperator(const ConditionalOperator *E) {
8222	bool IsBcpCall = false;
8223	// If the condition (ignoring parens) is a __builtin_constant_p call,
8224	// the result is a constant expression if it can be folded without
8225	// side-effects. This is an important GNU extension. See GCC PR38377
8226	// for discussion.
8227	if (const CallExpr *CallCE =
8228	dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts()))
8229	if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
8230	IsBcpCall = true;
8231
8232	// Always assume __builtin_constant_p(...) ? ... : ... is a potential
8233	// constant expression; we can't check whether it's potentially foldable.
8234	// FIXME: We should instead treat __builtin_constant_p as non-constant if
8235	// it would return 'false' in this mode.
8236	if (Info.checkingPotentialConstantExpression() && IsBcpCall)
8237	return false;
8238
8239	FoldConstant Fold(Info, IsBcpCall);
8240	if (!HandleConditionalOperator(E)) {
8241	Fold.keepDiagnostics();
8242	return false;
8243	}
8244
8245	return true;
8246	}
8247
8248	bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) {
8249	if (APValue *Value = Info.CurrentCall->getCurrentTemporary(Key: E);
8250	Value && !Value->isAbsent())
8251	return DerivedSuccess(V: *Value, E);
8252
8253	const Expr *Source = E->getSourceExpr();
8254	if (!Source)
8255	return Error(E);
8256	if (Source == E) {
8257	assert(0 && "OpaqueValueExpr recursively refers to itself");
8258	return Error(E);
8259	}
8260	return StmtVisitorTy::Visit(Source);
8261	}
8262
8263	bool VisitPseudoObjectExpr(const PseudoObjectExpr *E) {
8264	for (const Expr *SemE : E->semantics()) {
8265	if (auto *OVE = dyn_cast<OpaqueValueExpr>(SemE)) {
8266	// FIXME: We can't handle the case where an OpaqueValueExpr is also the
8267	// result expression: there could be two different LValues that would
8268	// refer to the same object in that case, and we can't model that.
8269	if (SemE == E->getResultExpr())
8270	return Error(E);
8271
8272	// Unique OVEs get evaluated if and when we encounter them when
8273	// emitting the rest of the semantic form, rather than eagerly.
8274	if (OVE->isUnique())
8275	continue;
8276
8277	LValue LV;
8278	if (!Evaluate(Info.CurrentCall->createTemporary(
8279	OVE, getStorageType(Info.Ctx, OVE),
8280	ScopeKind::FullExpression, LV),
8281	Info, OVE->getSourceExpr()))
8282	return false;
8283	} else if (SemE == E->getResultExpr()) {
8284	if (!StmtVisitorTy::Visit(SemE))
8285	return false;
8286	} else {
8287	if (!EvaluateIgnoredValue(Info, E: SemE))
8288	return false;
8289	}
8290	}
8291	return true;
8292	}
8293
8294	bool VisitCallExpr(const CallExpr *E) {
8295	APValue Result;
8296	if (!handleCallExpr(E, Result, ResultSlot: nullptr))
8297	return false;
8298	return DerivedSuccess(V: Result, E);
8299	}
8300
8301	bool handleCallExpr(const CallExpr *E, APValue &Result,
8302	const LValue *ResultSlot) {
8303	CallScopeRAII CallScope(Info);
8304
8305	const Expr *Callee = E->getCallee()->IgnoreParens();
8306	QualType CalleeType = Callee->getType();
8307
8308	const FunctionDecl *FD = nullptr;
8309	LValue *This = nullptr, ObjectArg;
8310	auto Args = llvm::ArrayRef(E->getArgs(), E->getNumArgs());
8311	bool HasQualifier = false;
8312
8313	CallRef Call;
8314
8315	// Extract function decl and 'this' pointer from the callee.
8316	if (CalleeType->isSpecificBuiltinType(K: BuiltinType::BoundMember)) {
8317	const CXXMethodDecl *Member = nullptr;
8318	if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) {
8319	// Explicit bound member calls, such as x.f() or p->g();
8320	if (!EvaluateObjectArgument(Info, Object: ME->getBase(), This&: ObjectArg))
8321	return false;
8322	Member = dyn_cast<CXXMethodDecl>(ME->getMemberDecl());
8323	if (!Member)
8324	return Error(Callee);
8325	This = &ObjectArg;
8326	HasQualifier = ME->hasQualifier();
8327	} else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) {
8328	// Indirect bound member calls ('.*' or '->*').
8329	const ValueDecl *D =
8330	HandleMemberPointerAccess(Info, BO: BE, LV&: ObjectArg, IncludeMember: false);
8331	if (!D)
8332	return false;
8333	Member = dyn_cast<CXXMethodDecl>(D);
8334	if (!Member)
8335	return Error(Callee);
8336	This = &ObjectArg;
8337	} else if (const auto *PDE = dyn_cast<CXXPseudoDestructorExpr>(Callee)) {
8338	if (!Info.getLangOpts().CPlusPlus20)
8339	Info.CCEDiag(PDE, diag::note_constexpr_pseudo_destructor);
8340	return EvaluateObjectArgument(Info, PDE->getBase(), ObjectArg) &&
8341	HandleDestruction(Info, PDE, ObjectArg, PDE->getDestroyedType());
8342	} else
8343	return Error(Callee);
8344	FD = Member;
8345	} else if (CalleeType->isFunctionPointerType()) {
8346	LValue CalleeLV;
8347	if (!EvaluatePointer(E: Callee, Result&: CalleeLV, Info))
8348	return false;
8349
8350	if (!CalleeLV.getLValueOffset().isZero())
8351	return Error(Callee);
8352	if (CalleeLV.isNullPointer()) {
8353	Info.FFDiag(Callee, diag::note_constexpr_null_callee)
8354	<< const_cast<Expr *>(Callee);
8355	return false;
8356	}
8357	FD = dyn_cast_or_null<FunctionDecl>(
8358	CalleeLV.getLValueBase().dyn_cast<const ValueDecl *>());
8359	if (!FD)
8360	return Error(Callee);
8361	// Don't call function pointers which have been cast to some other type.
8362	// Per DR (no number yet), the caller and callee can differ in noexcept.
8363	if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
8364	T: CalleeType->getPointeeType(), U: FD->getType())) {
8365	return Error(E);
8366	}
8367
8368	// For an (overloaded) assignment expression, evaluate the RHS before the
8369	// LHS.
8370	auto *OCE = dyn_cast<CXXOperatorCallExpr>(E);
8371	if (OCE && OCE->isAssignmentOp()) {
8372	assert(Args.size() == 2 && "wrong number of arguments in assignment");
8373	Call = Info.CurrentCall->createCall(Callee: FD);
8374	bool HasThis = false;
8375	if (const auto *MD = dyn_cast<CXXMethodDecl>(FD))
8376	HasThis = MD->isImplicitObjectMemberFunction();
8377	if (!EvaluateArgs(HasThis ? Args.slice(1) : Args, Call, Info, FD,
8378	/*RightToLeft=*/true, &ObjectArg))
8379	return false;
8380	}
8381
8382	// Overloaded operator calls to member functions are represented as normal
8383	// calls with '*this' as the first argument.
8384	const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
8385	if (MD &&
8386	(MD->isImplicitObjectMemberFunction() || (OCE && MD->isStatic()))) {
8387	// FIXME: When selecting an implicit conversion for an overloaded
8388	// operator delete, we sometimes try to evaluate calls to conversion
8389	// operators without a 'this' parameter!
8390	if (Args.empty())
8391	return Error(E);
8392
8393	if (!EvaluateObjectArgument(Info, Args[0], ObjectArg))
8394	return false;
8395
8396	// If we are calling a static operator, the 'this' argument needs to be
8397	// ignored after being evaluated.
8398	if (MD->isInstance())
8399	This = &ObjectArg;
8400
8401	// If this is syntactically a simple assignment using a trivial
8402	// assignment operator, start the lifetimes of union members as needed,
8403	// per C++20 [class.union]5.
8404	if (Info.getLangOpts().CPlusPlus20 && OCE &&
8405	OCE->getOperator() == OO_Equal && MD->isTrivial() &&
8406	!MaybeHandleUnionActiveMemberChange(Info, Args[0], ObjectArg))
8407	return false;
8408
8409	Args = Args.slice(1);
8410	} else if (MD && MD->isLambdaStaticInvoker()) {
8411	// Map the static invoker for the lambda back to the call operator.
8412	// Conveniently, we don't have to slice out the 'this' argument (as is
8413	// being done for the non-static case), since a static member function
8414	// doesn't have an implicit argument passed in.
8415	const CXXRecordDecl *ClosureClass = MD->getParent();
8416	assert(
8417	ClosureClass->captures_begin() == ClosureClass->captures_end() &&
8418	"Number of captures must be zero for conversion to function-ptr");
8419
8420	const CXXMethodDecl *LambdaCallOp =
8421	ClosureClass->getLambdaCallOperator();
8422
8423	// Set 'FD', the function that will be called below, to the call
8424	// operator. If the closure object represents a generic lambda, find
8425	// the corresponding specialization of the call operator.
8426
8427	if (ClosureClass->isGenericLambda()) {
8428	assert(MD->isFunctionTemplateSpecialization() &&
8429	"A generic lambda's static-invoker function must be a "
8430	"template specialization");
8431	const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
8432	FunctionTemplateDecl *CallOpTemplate =
8433	LambdaCallOp->getDescribedFunctionTemplate();
8434	void *InsertPos = nullptr;
8435	FunctionDecl *CorrespondingCallOpSpecialization =
8436	CallOpTemplate->findSpecialization(Args: TAL->asArray(), InsertPos);
8437	assert(CorrespondingCallOpSpecialization &&
8438	"We must always have a function call operator specialization "
8439	"that corresponds to our static invoker specialization");
8440	assert(isa<CXXMethodDecl>(CorrespondingCallOpSpecialization));
8441	FD = CorrespondingCallOpSpecialization;
8442	} else
8443	FD = LambdaCallOp;
8444	} else if (FD->isUsableAsGlobalAllocationFunctionInConstantEvaluation()) {
8445	if (FD->getDeclName().isAnyOperatorNew()) {
8446	LValue Ptr;
8447	if (!HandleOperatorNewCall(Info, E, Result&: Ptr))
8448	return false;
8449	Ptr.moveInto(V&: Result);
8450	return CallScope.destroy();
8451	} else {
8452	return HandleOperatorDeleteCall(Info, E) && CallScope.destroy();
8453	}
8454	}
8455	} else
8456	return Error(E);
8457
8458	// Evaluate the arguments now if we've not already done so.
8459	if (!Call) {
8460	Call = Info.CurrentCall->createCall(Callee: FD);
8461	if (!EvaluateArgs(Args, Call, Info, FD, /*RightToLeft*/ false,
8462	&ObjectArg))
8463	return false;
8464	}
8465
8466	SmallVector<QualType, 4> CovariantAdjustmentPath;
8467	if (This) {
8468	auto *NamedMember = dyn_cast<CXXMethodDecl>(FD);
8469	if (NamedMember && NamedMember->isVirtual() && !HasQualifier) {
8470	// Perform virtual dispatch, if necessary.
8471	FD = HandleVirtualDispatch(Info, E, *This, NamedMember,
8472	CovariantAdjustmentPath);
8473	if (!FD)
8474	return false;
8475	} else if (NamedMember && NamedMember->isImplicitObjectMemberFunction()) {
8476	// Check that the 'this' pointer points to an object of the right type.
8477	// FIXME: If this is an assignment operator call, we may need to change
8478	// the active union member before we check this.
8479	if (!checkNonVirtualMemberCallThisPointer(Info, E, *This, NamedMember))
8480	return false;
8481	}
8482	}
8483
8484	// Destructor calls are different enough that they have their own codepath.
8485	if (auto *DD = dyn_cast<CXXDestructorDecl>(FD)) {
8486	assert(This && "no 'this' pointer for destructor call");
8487	return HandleDestruction(Info, E, *This,
8488	Info.Ctx.getRecordType(Decl: DD->getParent())) &&
8489	CallScope.destroy();
8490	}
8491
8492	const FunctionDecl *Definition = nullptr;
8493	Stmt *Body = FD->getBody(Definition);
8494	SourceLocation Loc = E->getExprLoc();
8495
8496	// Treat the object argument as `this` when evaluating defaulted
8497	// special menmber functions
8498	if (FD->hasCXXExplicitFunctionObjectParameter())
8499	This = &ObjectArg;
8500
8501	if (!CheckConstexprFunction(Info, CallLoc: Loc, Declaration: FD, Definition, Body) ||
8502	!HandleFunctionCall(Loc, Definition, This, E, Args, Call, Body, Info,
8503	Result, ResultSlot))
8504	return false;
8505
8506	if (!CovariantAdjustmentPath.empty() &&
8507	!HandleCovariantReturnAdjustment(Info, E, Result,
8508	CovariantAdjustmentPath))
8509	return false;
8510
8511	return CallScope.destroy();
8512	}
8513
8514	bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
8515	return StmtVisitorTy::Visit(E->getInitializer());
8516	}
8517	bool VisitInitListExpr(const InitListExpr *E) {
8518	if (E->getNumInits() == 0)
8519	return DerivedZeroInitialization(E);
8520	if (E->getNumInits() == 1)
8521	return StmtVisitorTy::Visit(E->getInit(Init: 0));
8522	return Error(E);
8523	}
8524	bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
8525	return DerivedZeroInitialization(E);
8526	}
8527	bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) {
8528	return DerivedZeroInitialization(E);
8529	}
8530	bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) {
8531	return DerivedZeroInitialization(E);
8532	}
8533
8534	/// A member expression where the object is a prvalue is itself a prvalue.
8535	bool VisitMemberExpr(const MemberExpr *E) {
8536	assert(!Info.Ctx.getLangOpts().CPlusPlus11 &&
8537	"missing temporary materialization conversion");
8538	assert(!E->isArrow() && "missing call to bound member function?");
8539
8540	APValue Val;
8541	if (!Evaluate(Result&: Val, Info, E: E->getBase()))
8542	return false;
8543
8544	QualType BaseTy = E->getBase()->getType();
8545
8546	const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
8547	if (!FD) return Error(E);
8548	assert(!FD->getType()->isReferenceType() && "prvalue reference?");
8549	assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
8550	FD->getParent()->getCanonicalDecl() && "record / field mismatch");
8551
8552	// Note: there is no lvalue base here. But this case should only ever
8553	// happen in C or in C++98, where we cannot be evaluating a constexpr
8554	// constructor, which is the only case the base matters.
8555	CompleteObject Obj(APValue::LValueBase(), &Val, BaseTy);
8556	SubobjectDesignator Designator(BaseTy);
8557	Designator.addDeclUnchecked(FD);
8558
8559	APValue Result;
8560	return extractSubobject(Info, E, Obj, Designator, Result) &&
8561	DerivedSuccess(V: Result, E);
8562	}
8563
8564	bool VisitExtVectorElementExpr(const ExtVectorElementExpr *E) {
8565	APValue Val;
8566	if (!Evaluate(Result&: Val, Info, E: E->getBase()))
8567	return false;
8568
8569	if (Val.isVector()) {
8570	SmallVector<uint32_t, 4> Indices;
8571	E->getEncodedElementAccess(Elts&: Indices);
8572	if (Indices.size() == 1) {
8573	// Return scalar.
8574	return DerivedSuccess(V: Val.getVectorElt(Indices[0]), E);
8575	} else {
8576	// Construct new APValue vector.
8577	SmallVector<APValue, 4> Elts;
8578	for (unsigned I = 0; I < Indices.size(); ++I) {
8579	Elts.push_back(Val.getVectorElt(Indices[I]));
8580	}
8581	APValue VecResult(Elts.data(), Indices.size());
8582	return DerivedSuccess(V: VecResult, E);
8583	}
8584	}
8585
8586	return false;
8587	}
8588
8589	bool VisitCastExpr(const CastExpr *E) {
8590	switch (E->getCastKind()) {
8591	default:
8592	break;
8593
8594	case CK_AtomicToNonAtomic: {
8595	APValue AtomicVal;
8596	// This does not need to be done in place even for class/array types:
8597	// atomic-to-non-atomic conversion implies copying the object
8598	// representation.
8599	if (!Evaluate(Result&: AtomicVal, Info, E: E->getSubExpr()))
8600	return false;
8601	return DerivedSuccess(V: AtomicVal, E);
8602	}
8603
8604	case CK_NoOp:
8605	case CK_UserDefinedConversion:
8606	return StmtVisitorTy::Visit(E->getSubExpr());
8607
8608	case CK_LValueToRValue: {
8609	LValue LVal;
8610	if (!EvaluateLValue(E: E->getSubExpr(), Result&: LVal, Info))
8611	return false;
8612	APValue RVal;
8613	// Note, we use the subexpression's type in order to retain cv-qualifiers.
8614	if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
8615	LVal, RVal))
8616	return false;
8617	return DerivedSuccess(V: RVal, E);
8618	}
8619	case CK_LValueToRValueBitCast: {
8620	APValue DestValue, SourceValue;
8621	if (!Evaluate(Result&: SourceValue, Info, E: E->getSubExpr()))
8622	return false;
8623	if (!handleLValueToRValueBitCast(Info, DestValue, SourceValue, BCE: E))
8624	return false;
8625	return DerivedSuccess(V: DestValue, E);
8626	}
8627
8628	case CK_AddressSpaceConversion: {
8629	APValue Value;
8630	if (!Evaluate(Result&: Value, Info, E: E->getSubExpr()))
8631	return false;
8632	return DerivedSuccess(V: Value, E);
8633	}
8634	}
8635
8636	return Error(E);
8637	}
8638
8639	bool VisitUnaryPostInc(const UnaryOperator *UO) {
8640	return VisitUnaryPostIncDec(UO);
8641	}
8642	bool VisitUnaryPostDec(const UnaryOperator *UO) {
8643	return VisitUnaryPostIncDec(UO);
8644	}
8645	bool VisitUnaryPostIncDec(const UnaryOperator *UO) {
8646	if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
8647	return Error(UO);
8648
8649	LValue LVal;
8650	if (!EvaluateLValue(E: UO->getSubExpr(), Result&: LVal, Info))
8651	return false;
8652	APValue RVal;
8653	if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(),
8654	UO->isIncrementOp(), &RVal))
8655	return false;
8656	return DerivedSuccess(V: RVal, E: UO);
8657	}
8658
8659	bool VisitStmtExpr(const StmtExpr *E) {
8660	// We will have checked the full-expressions inside the statement expression
8661	// when they were completed, and don't need to check them again now.
8662	llvm::SaveAndRestore NotCheckingForUB(Info.CheckingForUndefinedBehavior,
8663	false);
8664
8665	const CompoundStmt *CS = E->getSubStmt();
8666	if (CS->body_empty())
8667	return true;
8668
8669	BlockScopeRAII Scope(Info);
8670	for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
8671	BE = CS->body_end();
8672	/**/; ++BI) {
8673	if (BI + 1 == BE) {
8674	const Expr *FinalExpr = dyn_cast<Expr>(*BI);
8675	if (!FinalExpr) {
8676	Info.FFDiag((*BI)->getBeginLoc(),
8677	diag::note_constexpr_stmt_expr_unsupported);
8678	return false;
8679	}
8680	return this->Visit(FinalExpr) && Scope.destroy();
8681	}
8682
8683	APValue ReturnValue;
8684	StmtResult Result = { .Value: ReturnValue, .Slot: nullptr };
8685	EvalStmtResult ESR = EvaluateStmt(Result, Info, S: *BI);
8686	if (ESR != ESR_Succeeded) {
8687	// FIXME: If the statement-expression terminated due to 'return',
8688	// 'break', or 'continue', it would be nice to propagate that to
8689	// the outer statement evaluation rather than bailing out.
8690	if (ESR != ESR_Failed)
8691	Info.FFDiag((*BI)->getBeginLoc(),
8692	diag::note_constexpr_stmt_expr_unsupported);
8693	return false;
8694	}
8695	}
8696
8697	llvm_unreachable("Return from function from the loop above.");
8698	}
8699
8700	bool VisitPackIndexingExpr(const PackIndexingExpr *E) {
8701	return StmtVisitorTy::Visit(E->getSelectedExpr());
8702	}
8703
8704	/// Visit a value which is evaluated, but whose value is ignored.
8705	void VisitIgnoredValue(const Expr *E) {
8706	EvaluateIgnoredValue(Info, E);
8707	}
8708
8709	/// Potentially visit a MemberExpr's base expression.
8710	void VisitIgnoredBaseExpression(const Expr *E) {
8711	// While MSVC doesn't evaluate the base expression, it does diagnose the
8712	// presence of side-effecting behavior.
8713	if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Ctx: Info.Ctx))
8714	return;
8715	VisitIgnoredValue(E);
8716	}
8717	};
8718
8719	} // namespace
8720
8721	//===----------------------------------------------------------------------===//
8722	// Common base class for lvalue and temporary evaluation.
8723	//===----------------------------------------------------------------------===//
8724	namespace {
8725	template<class Derived>
8726	class LValueExprEvaluatorBase
8727	: public ExprEvaluatorBase<Derived> {
8728	protected:
8729	LValue &Result;
8730	bool InvalidBaseOK;
8731	typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy;
8732	typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy;
8733
8734	bool Success(APValue::LValueBase B) {
8735	Result.set(B);
8736	return true;
8737	}
8738
8739	bool evaluatePointer(const Expr *E, LValue &Result) {
8740	return EvaluatePointer(E, Result, this->Info, InvalidBaseOK);
8741	}
8742
8743	public:
8744	LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK)
8745	: ExprEvaluatorBaseTy(Info), Result(Result),
8746	InvalidBaseOK(InvalidBaseOK) {}
8747
8748	bool Success(const APValue &V, const Expr *E) {
8749	Result.setFrom(Ctx&: this->Info.Ctx, V);
8750	return true;
8751	}
8752
8753	bool VisitMemberExpr(const MemberExpr *E) {
8754	// Handle non-static data members.
8755	QualType BaseTy;
8756	bool EvalOK;
8757	if (E->isArrow()) {
8758	EvalOK = evaluatePointer(E: E->getBase(), Result);
8759	BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType();
8760	} else if (E->getBase()->isPRValue()) {
8761	assert(E->getBase()->getType()->isRecordType());
8762	EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info);
8763	BaseTy = E->getBase()->getType();
8764	} else {
8765	EvalOK = this->Visit(E->getBase());
8766	BaseTy = E->getBase()->getType();
8767	}
8768	if (!EvalOK) {
8769	if (!InvalidBaseOK)
8770	return false;
8771	Result.setInvalid(E);
8772	return true;
8773	}
8774
8775	const ValueDecl *MD = E->getMemberDecl();
8776	if (const FieldDecl *FD = dyn_cast<FieldDecl>(Val: E->getMemberDecl())) {
8777	assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
8778	FD->getParent()->getCanonicalDecl() && "record / field mismatch");
8779	(void)BaseTy;
8780	if (!HandleLValueMember(this->Info, E, Result, FD))
8781	return false;
8782	} else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(Val: MD)) {
8783	if (!HandleLValueIndirectMember(this->Info, E, Result, IFD))
8784	return false;
8785	} else
8786	return this->Error(E);
8787
8788	if (MD->getType()->isReferenceType()) {
8789	APValue RefValue;
8790	if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result,
8791	RefValue))
8792	return false;
8793	return Success(RefValue, E);
8794	}
8795	return true;
8796	}
8797
8798	bool VisitBinaryOperator(const BinaryOperator *E) {
8799	switch (E->getOpcode()) {
8800	default:
8801	return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
8802
8803	case BO_PtrMemD:
8804	case BO_PtrMemI:
8805	return HandleMemberPointerAccess(this->Info, E, Result);
8806	}
8807	}
8808
8809	bool VisitCastExpr(const CastExpr *E) {
8810	switch (E->getCastKind()) {
8811	default:
8812	return ExprEvaluatorBaseTy::VisitCastExpr(E);
8813
8814	case CK_DerivedToBase:
8815	case CK_UncheckedDerivedToBase:
8816	if (!this->Visit(E->getSubExpr()))
8817	return false;
8818
8819	// Now figure out the necessary offset to add to the base LV to get from
8820	// the derived class to the base class.
8821	return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(),
8822	Result);
8823	}
8824	}
8825	};
8826	}
8827
8828	//===----------------------------------------------------------------------===//
8829	// LValue Evaluation
8830	//
8831	// This is used for evaluating lvalues (in C and C++), xvalues (in C++11),
8832	// function designators (in C), decl references to void objects (in C), and
8833	// temporaries (if building with -Wno-address-of-temporary).
8834	//
8835	// LValue evaluation produces values comprising a base expression of one of the
8836	// following types:
8837	// - Declarations
8838	// * VarDecl
8839	// * FunctionDecl
8840	// - Literals
8841	// * CompoundLiteralExpr in C (and in global scope in C++)
8842	// * StringLiteral
8843	// * PredefinedExpr
8844	// * ObjCStringLiteralExpr
8845	// * ObjCEncodeExpr
8846	// * AddrLabelExpr
8847	// * BlockExpr
8848	// * CallExpr for a MakeStringConstant builtin
8849	// - typeid(T) expressions, as TypeInfoLValues
8850	// - Locals and temporaries
8851	// * MaterializeTemporaryExpr
8852	// * Any Expr, with a CallIndex indicating the function in which the temporary
8853	// was evaluated, for cases where the MaterializeTemporaryExpr is missing
8854	// from the AST (FIXME).
8855	// * A MaterializeTemporaryExpr that has static storage duration, with no
8856	// CallIndex, for a lifetime-extended temporary.
8857	// * The ConstantExpr that is currently being evaluated during evaluation of an
8858	// immediate invocation.
8859	// plus an offset in bytes.
8860	//===----------------------------------------------------------------------===//
8861	namespace {
8862	class LValueExprEvaluator
8863	: public LValueExprEvaluatorBase<LValueExprEvaluator> {
8864	public:
8865	LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) :
8866	LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {}
8867
8868	bool VisitVarDecl(const Expr *E, const VarDecl *VD);
8869	bool VisitUnaryPreIncDec(const UnaryOperator *UO);
8870
8871	bool VisitCallExpr(const CallExpr *E);
8872	bool VisitDeclRefExpr(const DeclRefExpr *E);
8873	bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); }
8874	bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E);
8875	bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
8876	bool VisitMemberExpr(const MemberExpr *E);
8877	bool VisitStringLiteral(const StringLiteral *E) {
8878	return Success(B: APValue::LValueBase(
8879	E, 0, Info.getASTContext().getNextStringLiteralVersion()));
8880	}
8881	bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); }
8882	bool VisitCXXTypeidExpr(const CXXTypeidExpr *E);
8883	bool VisitCXXUuidofExpr(const CXXUuidofExpr *E);
8884	bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E);
8885	bool VisitExtVectorElementExpr(const ExtVectorElementExpr *E);
8886	bool VisitUnaryDeref(const UnaryOperator *E);
8887	bool VisitUnaryReal(const UnaryOperator *E);
8888	bool VisitUnaryImag(const UnaryOperator *E);
8889	bool VisitUnaryPreInc(const UnaryOperator *UO) {
8890	return VisitUnaryPreIncDec(UO);
8891	}
8892	bool VisitUnaryPreDec(const UnaryOperator *UO) {
8893	return VisitUnaryPreIncDec(UO);
8894	}
8895	bool VisitBinAssign(const BinaryOperator *BO);
8896	bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO);
8897
8898	bool VisitCastExpr(const CastExpr *E) {
8899	switch (E->getCastKind()) {
8900	default:
8901	return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
8902
8903	case CK_LValueBitCast:
8904	this->CCEDiag(E, diag::note_constexpr_invalid_cast)
8905	<< diag::ConstexprInvalidCastKind::ThisConversionOrReinterpret
8906	<< Info.Ctx.getLangOpts().CPlusPlus;
8907	if (!Visit(E->getSubExpr()))
8908	return false;
8909	Result.Designator.setInvalid();
8910	return true;
8911
8912	case CK_BaseToDerived:
8913	if (!Visit(E->getSubExpr()))
8914	return false;
8915	return HandleBaseToDerivedCast(Info, E, Result);
8916
8917	case CK_Dynamic:
8918	if (!Visit(E->getSubExpr()))
8919	return false;
8920	return HandleDynamicCast(Info, E: cast<ExplicitCastExpr>(Val: E), Ptr&: Result);
8921	}
8922	}
8923	};
8924	} // end anonymous namespace
8925
8926	/// Get an lvalue to a field of a lambda's closure type.
8927	static bool HandleLambdaCapture(EvalInfo &Info, const Expr *E, LValue &Result,
8928	const CXXMethodDecl *MD, const FieldDecl *FD,
8929	bool LValueToRValueConversion) {
8930	// Static lambda function call operators can't have captures. We already
8931	// diagnosed this, so bail out here.
8932	if (MD->isStatic()) {
8933	assert(Info.CurrentCall->This == nullptr &&
8934	"This should not be set for a static call operator");
8935	return false;
8936	}
8937
8938	// Start with 'Result' referring to the complete closure object...
8939	if (MD->isExplicitObjectMemberFunction()) {
8940	// Self may be passed by reference or by value.
8941	const ParmVarDecl *Self = MD->getParamDecl(0);
8942	if (Self->getType()->isReferenceType()) {
8943	APValue *RefValue = Info.getParamSlot(Call: Info.CurrentCall->Arguments, PVD: Self);
8944	if (!RefValue->allowConstexprUnknown() || RefValue->hasValue())
8945	Result.setFrom(Ctx&: Info.Ctx, V: *RefValue);
8946	} else {
8947	const ParmVarDecl *VD = Info.CurrentCall->Arguments.getOrigParam(PVD: Self);
8948	CallStackFrame *Frame =
8949	Info.getCallFrameAndDepth(CallIndex: Info.CurrentCall->Arguments.CallIndex)
8950	.first;
8951	unsigned Version = Info.CurrentCall->Arguments.Version;
8952	Result.set({VD, Frame->Index, Version});
8953	}
8954	} else
8955	Result = *Info.CurrentCall->This;
8956
8957	// ... then update it to refer to the field of the closure object
8958	// that represents the capture.
8959	if (!HandleLValueMember(Info, E, LVal&: Result, FD))
8960	return false;
8961
8962	// And if the field is of reference type (or if we captured '*this' by
8963	// reference), update 'Result' to refer to what
8964	// the field refers to.
8965	if (LValueToRValueConversion) {
8966	APValue RVal;
8967	if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result, RVal))
8968	return false;
8969	Result.setFrom(Ctx&: Info.Ctx, V: RVal);
8970	}
8971	return true;
8972	}
8973
8974	/// Evaluate an expression as an lvalue. This can be legitimately called on
8975	/// expressions which are not glvalues, in three cases:
8976	/// * function designators in C, and
8977	/// * "extern void" objects
8978	/// * @selector() expressions in Objective-C
8979	static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
8980	bool InvalidBaseOK) {
8981	assert(!E->isValueDependent());
8982	assert(E->isGLValue() || E->getType()->isFunctionType() ||
8983	E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E->IgnoreParens()));
8984	return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
8985	}
8986
8987	bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
8988	const NamedDecl *D = E->getDecl();
8989	if (isa<FunctionDecl, MSGuidDecl, TemplateParamObjectDecl,
8990	UnnamedGlobalConstantDecl>(Val: D))
8991	return Success(B: cast<ValueDecl>(Val: D));
8992	if (const VarDecl *VD = dyn_cast<VarDecl>(Val: D))
8993	return VisitVarDecl(E, VD);
8994	if (const BindingDecl *BD = dyn_cast<BindingDecl>(Val: D))
8995	return Visit(BD->getBinding());
8996	return Error(E);
8997	}
8998
8999	bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
9000	// If we are within a lambda's call operator, check whether the 'VD' referred
9001	// to within 'E' actually represents a lambda-capture that maps to a
9002	// data-member/field within the closure object, and if so, evaluate to the
9003	// field or what the field refers to.
9004	if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) &&
9005	isa<DeclRefExpr>(Val: E) &&
9006	cast<DeclRefExpr>(Val: E)->refersToEnclosingVariableOrCapture()) {
9007	// We don't always have a complete capture-map when checking or inferring if
9008	// the function call operator meets the requirements of a constexpr function
9009	// - but we don't need to evaluate the captures to determine constexprness
9010	// (dcl.constexpr C++17).
9011	if (Info.checkingPotentialConstantExpression())
9012	return false;
9013
9014	if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) {
9015	const auto *MD = cast<CXXMethodDecl>(Val: Info.CurrentCall->Callee);
9016	return HandleLambdaCapture(Info, E, Result, MD, FD,
9017	FD->getType()->isReferenceType());
9018	}
9019	}
9020
9021	CallStackFrame *Frame = nullptr;
9022	unsigned Version = 0;
9023	if (VD->hasLocalStorage()) {
9024	// Only if a local variable was declared in the function currently being
9025	// evaluated, do we expect to be able to find its value in the current
9026	// frame. (Otherwise it was likely declared in an enclosing context and
9027	// could either have a valid evaluatable value (for e.g. a constexpr
9028	// variable) or be ill-formed (and trigger an appropriate evaluation
9029	// diagnostic)).
9030	CallStackFrame *CurrFrame = Info.CurrentCall;
9031	if (CurrFrame->Callee && CurrFrame->Callee->Equals(DC: VD->getDeclContext())) {
9032	// Function parameters are stored in some caller's frame. (Usually the
9033	// immediate caller, but for an inherited constructor they may be more
9034	// distant.)
9035	if (auto *PVD = dyn_cast<ParmVarDecl>(Val: VD)) {
9036	if (CurrFrame->Arguments) {
9037	VD = CurrFrame->Arguments.getOrigParam(PVD);
9038	Frame =
9039	Info.getCallFrameAndDepth(CallIndex: CurrFrame->Arguments.CallIndex).first;
9040	Version = CurrFrame->Arguments.Version;
9041	}
9042	} else {
9043	Frame = CurrFrame;
9044	Version = CurrFrame->getCurrentTemporaryVersion(Key: VD);
9045	}
9046	}
9047	}
9048
9049	if (!VD->getType()->isReferenceType()) {
9050	if (Frame) {
9051	Result.set({VD, Frame->Index, Version});
9052	return true;
9053	}
9054	return Success(VD);
9055	}
9056
9057	if (!Info.getLangOpts().CPlusPlus11) {
9058	Info.CCEDiag(E, diag::note_constexpr_ltor_non_integral, 1)
9059	<< VD << VD->getType();
9060	Info.Note(VD->getLocation(), diag::note_declared_at);
9061	}
9062
9063	APValue *V;
9064	if (!evaluateVarDeclInit(Info, E, VD, Frame, Version, Result&: V))
9065	return false;
9066
9067	return Success(V: *V, E);
9068	}
9069
9070	bool LValueExprEvaluator::VisitCallExpr(const CallExpr *E) {
9071	if (!IsConstantEvaluatedBuiltinCall(E))
9072	return ExprEvaluatorBaseTy::VisitCallExpr(E);
9073
9074	switch (E->getBuiltinCallee()) {
9075	default:
9076	return false;
9077	case Builtin::BIas_const:
9078	case Builtin::BIforward:
9079	case Builtin::BIforward_like:
9080	case Builtin::BImove:
9081	case Builtin::BImove_if_noexcept:
9082	if (cast<FunctionDecl>(Val: E->getCalleeDecl())->isConstexpr())
9083	return Visit(E->getArg(Arg: 0));
9084	break;
9085	}
9086
9087	return ExprEvaluatorBaseTy::VisitCallExpr(E);
9088	}
9089
9090	bool LValueExprEvaluator::VisitMaterializeTemporaryExpr(
9091	const MaterializeTemporaryExpr *E) {
9092	// Walk through the expression to find the materialized temporary itself.
9093	SmallVector<const Expr *, 2> CommaLHSs;
9094	SmallVector<SubobjectAdjustment, 2> Adjustments;
9095	const Expr *Inner =
9096	E->getSubExpr()->skipRValueSubobjectAdjustments(CommaLHS&: CommaLHSs, Adjustments);
9097
9098	// If we passed any comma operators, evaluate their LHSs.
9099	for (const Expr *E : CommaLHSs)
9100	if (!EvaluateIgnoredValue(Info, E))
9101	return false;
9102
9103	// A materialized temporary with static storage duration can appear within the
9104	// result of a constant expression evaluation, so we need to preserve its
9105	// value for use outside this evaluation.
9106	APValue *Value;
9107	if (E->getStorageDuration() == SD_Static) {
9108	if (Info.EvalMode == EvalInfo::EM_ConstantFold)
9109	return false;
9110	// FIXME: What about SD_Thread?
9111	Value = E->getOrCreateValue(MayCreate: true);
9112	*Value = APValue();
9113	Result.set(E);
9114	} else {
9115	Value = &Info.CurrentCall->createTemporary(
9116	Key: E, T: Inner->getType(),
9117	Scope: E->getStorageDuration() == SD_FullExpression ? ScopeKind::FullExpression
9118	: ScopeKind::Block,
9119	LV&: Result);
9120	}
9121
9122	QualType Type = Inner->getType();
9123
9124	// Materialize the temporary itself.
9125	if (!EvaluateInPlace(Result&: *Value, Info, This: Result, E: Inner)) {
9126	*Value = APValue();
9127	return false;
9128	}
9129
9130	// Adjust our lvalue to refer to the desired subobject.
9131	for (unsigned I = Adjustments.size(); I != 0; /**/) {
9132	--I;
9133	switch (Adjustments[I].Kind) {
9134	case SubobjectAdjustment::DerivedToBaseAdjustment:
9135	if (!HandleLValueBasePath(Info, E: Adjustments[I].DerivedToBase.BasePath,
9136	Type, Result))
9137	return false;
9138	Type = Adjustments[I].DerivedToBase.BasePath->getType();
9139	break;
9140
9141	case SubobjectAdjustment::FieldAdjustment:
9142	if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field))
9143	return false;
9144	Type = Adjustments[I].Field->getType();
9145	break;
9146
9147	case SubobjectAdjustment::MemberPointerAdjustment:
9148	if (!HandleMemberPointerAccess(Info&: this->Info, LVType: Type, LV&: Result,
9149	RHS: Adjustments[I].Ptr.RHS))
9150	return false;
9151	Type = Adjustments[I].Ptr.MPT->getPointeeType();
9152	break;
9153	}
9154	}
9155
9156	return true;
9157	}
9158
9159	bool
9160	LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
9161	assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&
9162	"lvalue compound literal in c++?");
9163	// Defer visiting the literal until the lvalue-to-rvalue conversion. We can
9164	// only see this when folding in C, so there's no standard to follow here.
9165	return Success(E);
9166	}
9167
9168	bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
9169	TypeInfoLValue TypeInfo;
9170
9171	if (!E->isPotentiallyEvaluated()) {
9172	if (E->isTypeOperand())
9173	TypeInfo = TypeInfoLValue(E->getTypeOperand(Context: Info.Ctx).getTypePtr());
9174	else
9175	TypeInfo = TypeInfoLValue(E->getExprOperand()->getType().getTypePtr());
9176	} else {
9177	if (!Info.Ctx.getLangOpts().CPlusPlus20) {
9178	Info.CCEDiag(E, diag::note_constexpr_typeid_polymorphic)
9179	<< E->getExprOperand()->getType()
9180	<< E->getExprOperand()->getSourceRange();
9181	}
9182
9183	if (!Visit(E->getExprOperand()))
9184	return false;
9185
9186	std::optional<DynamicType> DynType =
9187	ComputeDynamicType(Info, E, Result, AK_TypeId);
9188	if (!DynType)
9189	return false;
9190
9191	TypeInfo =
9192	TypeInfoLValue(Info.Ctx.getRecordType(DynType->Type).getTypePtr());
9193	}
9194
9195	return Success(APValue::LValueBase::getTypeInfo(LV: TypeInfo, TypeInfo: E->getType()));
9196	}
9197
9198	bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) {
9199	return Success(E->getGuidDecl());
9200	}
9201
9202	bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
9203	// Handle static data members.
9204	if (const VarDecl *VD = dyn_cast<VarDecl>(Val: E->getMemberDecl())) {
9205	VisitIgnoredBaseExpression(E: E->getBase());
9206	return VisitVarDecl(E, VD);
9207	}
9208
9209	// Handle static member functions.
9210	if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Val: E->getMemberDecl())) {
9211	if (MD->isStatic()) {
9212	VisitIgnoredBaseExpression(E: E->getBase());
9213	return Success(MD);
9214	}
9215	}
9216
9217	// Handle non-static data members.
9218	return LValueExprEvaluatorBaseTy::VisitMemberExpr(E);
9219	}
9220
9221	bool LValueExprEvaluator::VisitExtVectorElementExpr(
9222	const ExtVectorElementExpr *E) {
9223	bool Success = true;
9224
9225	APValue Val;
9226	if (!Evaluate(Result&: Val, Info, E: E->getBase())) {
9227	if (!Info.noteFailure())
9228	return false;
9229	Success = false;
9230	}
9231
9232	SmallVector<uint32_t, 4> Indices;
9233	E->getEncodedElementAccess(Elts&: Indices);
9234	// FIXME: support accessing more than one element
9235	if (Indices.size() > 1)
9236	return false;
9237
9238	if (Success) {
9239	Result.setFrom(Ctx&: Info.Ctx, V: Val);
9240	QualType BaseType = E->getBase()->getType();
9241	if (E->isArrow())
9242	BaseType = BaseType->getPointeeType();
9243	const auto *VT = BaseType->castAs<VectorType>();
9244	HandleLValueVectorElement(Info, E, Result, VT->getElementType(),
9245	VT->getNumElements(), Indices[0]);
9246	}
9247
9248	return Success;
9249	}
9250
9251	bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
9252	if (E->getBase()->getType()->isSveVLSBuiltinType())
9253	return Error(E);
9254
9255	APSInt Index;
9256	bool Success = true;
9257
9258	if (const auto *VT = E->getBase()->getType()->getAs<VectorType>()) {
9259	APValue Val;
9260	if (!Evaluate(Result&: Val, Info, E: E->getBase())) {
9261	if (!Info.noteFailure())
9262	return false;
9263	Success = false;
9264	}
9265
9266	if (!EvaluateInteger(E: E->getIdx(), Result&: Index, Info)) {
9267	if (!Info.noteFailure())
9268	return false;
9269	Success = false;
9270	}
9271
9272	if (Success) {
9273	Result.setFrom(Ctx&: Info.Ctx, V: Val);
9274	HandleLValueVectorElement(Info, E, Result, VT->getElementType(),
9275	VT->getNumElements(), Index.getExtValue());
9276	}
9277
9278	return Success;
9279	}
9280
9281	// C++17's rules require us to evaluate the LHS first, regardless of which
9282	// side is the base.
9283	for (const Expr *SubExpr : {E->getLHS(), E->getRHS()}) {
9284	if (SubExpr == E->getBase() ? !evaluatePointer(E: SubExpr, Result)
9285	: !EvaluateInteger(E: SubExpr, Result&: Index, Info)) {
9286	if (!Info.noteFailure())
9287	return false;
9288	Success = false;
9289	}
9290	}
9291
9292	return Success &&
9293	HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index);
9294	}
9295
9296	bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) {
9297	return evaluatePointer(E: E->getSubExpr(), Result);
9298	}
9299
9300	bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
9301	if (!Visit(E->getSubExpr()))
9302	return false;
9303	// __real is a no-op on scalar lvalues.
9304	if (E->getSubExpr()->getType()->isAnyComplexType())
9305	HandleLValueComplexElement(Info, E, Result, E->getType(), false);
9306	return true;
9307	}
9308
9309	bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
9310	assert(E->getSubExpr()->getType()->isAnyComplexType() &&
9311	"lvalue __imag__ on scalar?");
9312	if (!Visit(E->getSubExpr()))
9313	return false;
9314	HandleLValueComplexElement(Info, E, Result, E->getType(), true);
9315	return true;
9316	}
9317
9318	bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) {
9319	if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
9320	return Error(UO);
9321
9322	if (!this->Visit(UO->getSubExpr()))
9323	return false;
9324
9325	return handleIncDec(
9326	this->Info, UO, Result, UO->getSubExpr()->getType(),
9327	UO->isIncrementOp(), nullptr);
9328	}
9329
9330	bool LValueExprEvaluator::VisitCompoundAssignOperator(
9331	const CompoundAssignOperator *CAO) {
9332	if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
9333	return Error(CAO);
9334
9335	bool Success = true;
9336
9337	// C++17 onwards require that we evaluate the RHS first.
9338	APValue RHS;
9339	if (!Evaluate(RHS, this->Info, CAO->getRHS())) {
9340	if (!Info.noteFailure())
9341	return false;
9342	Success = false;
9343	}
9344
9345	// The overall lvalue result is the result of evaluating the LHS.
9346	if (!this->Visit(CAO->getLHS()) || !Success)
9347	return false;
9348
9349	return handleCompoundAssignment(
9350	this->Info, CAO,
9351	Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(),
9352	CAO->getOpForCompoundAssignment(Opc: CAO->getOpcode()), RHS);
9353	}
9354
9355	bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) {
9356	if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
9357	return Error(E);
9358
9359	bool Success = true;
9360
9361	// C++17 onwards require that we evaluate the RHS first.
9362	APValue NewVal;
9363	if (!Evaluate(Result&: NewVal, Info&: this->Info, E: E->getRHS())) {
9364	if (!Info.noteFailure())
9365	return false;
9366	Success = false;
9367	}
9368
9369	if (!this->Visit(E->getLHS()) || !Success)
9370	return false;
9371
9372	if (Info.getLangOpts().CPlusPlus20 &&
9373	!MaybeHandleUnionActiveMemberChange(Info, LHSExpr: E->getLHS(), LHS: Result))
9374	return false;
9375
9376	return handleAssignment(this->Info, E, Result, E->getLHS()->getType(),
9377	NewVal);
9378	}
9379
9380	//===----------------------------------------------------------------------===//
9381	// Pointer Evaluation
9382	//===----------------------------------------------------------------------===//
9383
9384	/// Attempts to compute the number of bytes available at the pointer
9385	/// returned by a function with the alloc_size attribute. Returns true if we
9386	/// were successful. Places an unsigned number into `Result`.
9387	///
9388	/// This expects the given CallExpr to be a call to a function with an
9389	/// alloc_size attribute.
9390	static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
9391	const CallExpr *Call,
9392	llvm::APInt &Result) {
9393	const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call);
9394
9395	assert(AllocSize && AllocSize->getElemSizeParam().isValid());
9396	unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex();
9397	unsigned BitsInSizeT = Ctx.getTypeSize(T: Ctx.getSizeType());
9398	if (Call->getNumArgs() <= SizeArgNo)
9399	return false;
9400
9401	auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) {
9402	Expr::EvalResult ExprResult;
9403	if (!E->EvaluateAsInt(Result&: ExprResult, Ctx, AllowSideEffects: Expr::SE_AllowSideEffects))
9404	return false;
9405	Into = ExprResult.Val.getInt();
9406	if (Into.isNegative() || !Into.isIntN(N: BitsInSizeT))
9407	return false;
9408	Into = Into.zext(width: BitsInSizeT);
9409	return true;
9410	};
9411
9412	APSInt SizeOfElem;
9413	if (!EvaluateAsSizeT(Call->getArg(Arg: SizeArgNo), SizeOfElem))
9414	return false;
9415
9416	if (!AllocSize->getNumElemsParam().isValid()) {
9417	Result = std::move(SizeOfElem);
9418	return true;
9419	}
9420
9421	APSInt NumberOfElems;
9422	unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex();
9423	if (!EvaluateAsSizeT(Call->getArg(Arg: NumArgNo), NumberOfElems))
9424	return false;
9425
9426	bool Overflow;
9427	llvm::APInt BytesAvailable = SizeOfElem.umul_ov(RHS: NumberOfElems, Overflow);
9428	if (Overflow)
9429	return false;
9430
9431	Result = std::move(BytesAvailable);
9432	return true;
9433	}
9434
9435	/// Convenience function. LVal's base must be a call to an alloc_size
9436	/// function.
9437	static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
9438	const LValue &LVal,
9439	llvm::APInt &Result) {
9440	assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
9441	"Can't get the size of a non alloc_size function");
9442	const auto *Base = LVal.getLValueBase().get<const Expr *>();
9443	const CallExpr *CE = tryUnwrapAllocSizeCall(E: Base);
9444	return getBytesReturnedByAllocSizeCall(Ctx, Call: CE, Result);
9445	}
9446
9447	/// Attempts to evaluate the given LValueBase as the result of a call to
9448	/// a function with the alloc_size attribute. If it was possible to do so, this
9449	/// function will return true, make Result's Base point to said function call,
9450	/// and mark Result's Base as invalid.
9451	static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base,
9452	LValue &Result) {
9453	if (Base.isNull())
9454	return false;
9455
9456	// Because we do no form of static analysis, we only support const variables.
9457	//
9458	// Additionally, we can't support parameters, nor can we support static
9459	// variables (in the latter case, use-before-assign isn't UB; in the former,
9460	// we have no clue what they'll be assigned to).
9461	const auto *VD =
9462	dyn_cast_or_null<VarDecl>(Val: Base.dyn_cast<const ValueDecl *>());
9463	if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified())
9464	return false;
9465
9466	const Expr *Init = VD->getAnyInitializer();
9467	if (!Init || Init->getType().isNull())
9468	return false;
9469
9470	const Expr *E = Init->IgnoreParens();
9471	if (!tryUnwrapAllocSizeCall(E))
9472	return false;
9473
9474	// Store E instead of E unwrapped so that the type of the LValue's base is
9475	// what the user wanted.
9476	Result.setInvalid(B: E);
9477
9478	QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType();
9479	Result.addUnsizedArray(Info, E, ElemTy: Pointee);
9480	return true;
9481	}
9482
9483	namespace {
9484	class PointerExprEvaluator
9485	: public ExprEvaluatorBase<PointerExprEvaluator> {
9486	LValue &Result;
9487	bool InvalidBaseOK;
9488
9489	bool Success(const Expr *E) {
9490	Result.set(B: E);
9491	return true;
9492	}
9493
9494	bool evaluateLValue(const Expr *E, LValue &Result) {
9495	return EvaluateLValue(E, Result, Info, InvalidBaseOK);
9496	}
9497
9498	bool evaluatePointer(const Expr *E, LValue &Result) {
9499	return EvaluatePointer(E, Result, Info, InvalidBaseOK);
9500	}
9501
9502	bool visitNonBuiltinCallExpr(const CallExpr *E);
9503	public:
9504
9505	PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK)
9506	: ExprEvaluatorBaseTy(info), Result(Result),
9507	InvalidBaseOK(InvalidBaseOK) {}
9508
9509	bool Success(const APValue &V, const Expr *E) {
9510	Result.setFrom(Ctx&: Info.Ctx, V);
9511	return true;
9512	}
9513	bool ZeroInitialization(const Expr *E) {
9514	Result.setNull(Ctx&: Info.Ctx, PointerTy: E->getType());
9515	return true;
9516	}
9517
9518	bool VisitBinaryOperator(const BinaryOperator *E);
9519	bool VisitCastExpr(const CastExpr* E);
9520	bool VisitUnaryAddrOf(const UnaryOperator *E);
9521	bool VisitObjCStringLiteral(const ObjCStringLiteral *E)
9522	{ return Success(E); }
9523	bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
9524	if (E->isExpressibleAsConstantInitializer())
9525	return Success(E);
9526	if (Info.noteFailure())
9527	EvaluateIgnoredValue(Info, E: E->getSubExpr());
9528	return Error(E);
9529	}
9530	bool VisitAddrLabelExpr(const AddrLabelExpr *E)
9531	{ return Success(E); }
9532	bool VisitCallExpr(const CallExpr *E);
9533	bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
9534	bool VisitBlockExpr(const BlockExpr *E) {
9535	if (!E->getBlockDecl()->hasCaptures())
9536	return Success(E);
9537	return Error(E);
9538	}
9539	bool VisitCXXThisExpr(const CXXThisExpr *E) {
9540	auto DiagnoseInvalidUseOfThis = [&] {
9541	if (Info.getLangOpts().CPlusPlus11)
9542	Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit();
9543	else
9544	Info.FFDiag(E);
9545	};
9546
9547	// Can't look at 'this' when checking a potential constant expression.
9548	if (Info.checkingPotentialConstantExpression())
9549	return false;
9550
9551	bool IsExplicitLambda =
9552	isLambdaCallWithExplicitObjectParameter(Info.CurrentCall->Callee);
9553	if (!IsExplicitLambda) {
9554	if (!Info.CurrentCall->This) {
9555	DiagnoseInvalidUseOfThis();
9556	return false;
9557	}
9558
9559	Result = *Info.CurrentCall->This;
9560	}
9561
9562	if (isLambdaCallOperator(Info.CurrentCall->Callee)) {
9563	// Ensure we actually have captured 'this'. If something was wrong with
9564	// 'this' capture, the error would have been previously reported.
9565	// Otherwise we can be inside of a default initialization of an object
9566	// declared by lambda's body, so no need to return false.
9567	if (!Info.CurrentCall->LambdaThisCaptureField) {
9568	if (IsExplicitLambda && !Info.CurrentCall->This) {
9569	DiagnoseInvalidUseOfThis();
9570	return false;
9571	}
9572
9573	return true;
9574	}
9575
9576	const auto *MD = cast<CXXMethodDecl>(Val: Info.CurrentCall->Callee);
9577	return HandleLambdaCapture(
9578	Info, E, Result, MD, Info.CurrentCall->LambdaThisCaptureField,
9579	Info.CurrentCall->LambdaThisCaptureField->getType()->isPointerType());
9580	}
9581	return true;
9582	}
9583
9584	bool VisitCXXNewExpr(const CXXNewExpr *E);
9585
9586	bool VisitSourceLocExpr(const SourceLocExpr *E) {
9587	assert(!E->isIntType() && "SourceLocExpr isn't a pointer type?");
9588	APValue LValResult = E->EvaluateInContext(
9589	Ctx: Info.Ctx, DefaultExpr: Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr());
9590	Result.setFrom(Ctx&: Info.Ctx, V: LValResult);
9591	return true;
9592	}
9593
9594	bool VisitEmbedExpr(const EmbedExpr *E) {
9595	llvm::report_fatal_error(reason: "Not yet implemented for ExprConstant.cpp");
9596	return true;
9597	}
9598
9599	bool VisitSYCLUniqueStableNameExpr(const SYCLUniqueStableNameExpr *E) {
9600	std::string ResultStr = E->ComputeName(Context&: Info.Ctx);
9601
9602	QualType CharTy = Info.Ctx.CharTy.withConst();
9603	APInt Size(Info.Ctx.getTypeSize(T: Info.Ctx.getSizeType()),
9604	ResultStr.size() + 1);
9605	QualType ArrayTy = Info.Ctx.getConstantArrayType(
9606	EltTy: CharTy, ArySize: Size, SizeExpr: nullptr, ASM: ArraySizeModifier::Normal, IndexTypeQuals: 0);
9607
9608	StringLiteral *SL =
9609	StringLiteral::Create(Ctx: Info.Ctx, Str: ResultStr, Kind: StringLiteralKind::Ordinary,
9610	/*Pascal*/ false, Ty: ArrayTy, Loc: E->getLocation());
9611
9612	evaluateLValue(SL, Result);
9613	Result.addArray(Info, E, cast<ConstantArrayType>(Val&: ArrayTy));
9614	return true;
9615	}
9616
9617	// FIXME: Missing: @protocol, @selector
9618	};
9619	} // end anonymous namespace
9620
9621	static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info,
9622	bool InvalidBaseOK) {
9623	assert(!E->isValueDependent());
9624	assert(E->isPRValue() && E->getType()->hasPointerRepresentation());
9625	return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
9626	}
9627
9628	bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
9629	if (E->getOpcode() != BO_Add &&
9630	E->getOpcode() != BO_Sub)
9631	return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
9632
9633	const Expr *PExp = E->getLHS();
9634	const Expr *IExp = E->getRHS();
9635	if (IExp->getType()->isPointerType())
9636	std::swap(a&: PExp, b&: IExp);
9637
9638	bool EvalPtrOK = evaluatePointer(E: PExp, Result);
9639	if (!EvalPtrOK && !Info.noteFailure())
9640	return false;
9641
9642	llvm::APSInt Offset;
9643	if (!EvaluateInteger(E: IExp, Result&: Offset, Info) || !EvalPtrOK)
9644	return false;
9645
9646	if (E->getOpcode() == BO_Sub)
9647	negateAsSigned(Int&: Offset);
9648
9649	QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType();
9650	return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset);
9651	}
9652
9653	bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
9654	return evaluateLValue(E: E->getSubExpr(), Result);
9655	}
9656
9657	// Is the provided decl 'std::source_location::current'?
9658	static bool IsDeclSourceLocationCurrent(const FunctionDecl *FD) {
9659	if (!FD)
9660	return false;
9661	const IdentifierInfo *FnII = FD->getIdentifier();
9662	if (!FnII || !FnII->isStr(Str: "current"))
9663	return false;
9664
9665	const auto *RD = dyn_cast<RecordDecl>(FD->getParent());
9666	if (!RD)
9667	return false;
9668
9669	const IdentifierInfo *ClassII = RD->getIdentifier();
9670	return RD->isInStdNamespace() && ClassII && ClassII->isStr(Str: "source_location");
9671	}
9672
9673	bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
9674	const Expr *SubExpr = E->getSubExpr();
9675
9676	switch (E->getCastKind()) {
9677	default:
9678	break;
9679	case CK_BitCast:
9680	case CK_CPointerToObjCPointerCast:
9681	case CK_BlockPointerToObjCPointerCast:
9682	case CK_AnyPointerToBlockPointerCast:
9683	case CK_AddressSpaceConversion:
9684	if (!Visit(SubExpr))
9685	return false;
9686	// Bitcasts to cv void* are static_casts, not reinterpret_casts, so are
9687	// permitted in constant expressions in C++11. Bitcasts from cv void* are
9688	// also static_casts, but we disallow them as a resolution to DR1312.
9689	if (!E->getType()->isVoidPointerType()) {
9690	// In some circumstances, we permit casting from void* to cv1 T*, when the
9691	// actual pointee object is actually a cv2 T.
9692	bool HasValidResult = !Result.InvalidBase && !Result.Designator.Invalid &&
9693	!Result.IsNullPtr;
9694	bool VoidPtrCastMaybeOK =
9695	Result.IsNullPtr ||
9696	(HasValidResult &&
9697	Info.Ctx.hasSimilarType(T1: Result.Designator.getType(Info.Ctx),
9698	T2: E->getType()->getPointeeType()));
9699	// 1. We'll allow it in std::allocator::allocate, and anything which that
9700	// calls.
9701	// 2. HACK 2022-03-28: Work around an issue with libstdc++'s
9702	// <source_location> header. Fixed in GCC 12 and later (2022-04-??).
9703	// We'll allow it in the body of std::source_location::current. GCC's
9704	// implementation had a parameter of type `void*`, and casts from
9705	// that back to `const __impl*` in its body.
9706	if (VoidPtrCastMaybeOK &&
9707	(Info.getStdAllocatorCaller(FnName: "allocate") ||
9708	IsDeclSourceLocationCurrent(FD: Info.CurrentCall->Callee) ||
9709	Info.getLangOpts().CPlusPlus26)) {
9710	// Permitted.
9711	} else {
9712	if (SubExpr->getType()->isVoidPointerType() &&
9713	Info.getLangOpts().CPlusPlus) {
9714	if (HasValidResult)
9715	CCEDiag(E, diag::note_constexpr_invalid_void_star_cast)
9716	<< SubExpr->getType() << Info.getLangOpts().CPlusPlus26
9717	<< Result.Designator.getType(Info.Ctx).getCanonicalType()
9718	<< E->getType()->getPointeeType();
9719	else
9720	CCEDiag(E, diag::note_constexpr_invalid_cast)
9721	<< diag::ConstexprInvalidCastKind::CastFrom
9722	<< SubExpr->getType();
9723	} else
9724	CCEDiag(E, diag::note_constexpr_invalid_cast)
9725	<< diag::ConstexprInvalidCastKind::ThisConversionOrReinterpret
9726	<< Info.Ctx.getLangOpts().CPlusPlus;
9727	Result.Designator.setInvalid();
9728	}
9729	}
9730	if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr)
9731	ZeroInitialization(E);
9732	return true;
9733
9734	case CK_DerivedToBase:
9735	case CK_UncheckedDerivedToBase:
9736	if (!evaluatePointer(E: E->getSubExpr(), Result))
9737	return false;
9738	if (!Result.Base && Result.Offset.isZero())
9739	return true;
9740
9741	// Now figure out the necessary offset to add to the base LV to get from
9742	// the derived class to the base class.
9743	return HandleLValueBasePath(Info, E, Type: E->getSubExpr()->getType()->
9744	castAs<PointerType>()->getPointeeType(),
9745	Result);
9746
9747	case CK_BaseToDerived:
9748	if (!Visit(E->getSubExpr()))
9749	return false;
9750	if (!Result.Base && Result.Offset.isZero())
9751	return true;
9752	return HandleBaseToDerivedCast(Info, E, Result);
9753
9754	case CK_Dynamic:
9755	if (!Visit(E->getSubExpr()))
9756	return false;
9757	return HandleDynamicCast(Info, E: cast<ExplicitCastExpr>(Val: E), Ptr&: Result);
9758
9759	case CK_NullToPointer:
9760	VisitIgnoredValue(E: E->getSubExpr());
9761	return ZeroInitialization(E);
9762
9763	case CK_IntegralToPointer: {
9764	CCEDiag(E, diag::note_constexpr_invalid_cast)
9765	<< diag::ConstexprInvalidCastKind::ThisConversionOrReinterpret
9766	<< Info.Ctx.getLangOpts().CPlusPlus;
9767
9768	APValue Value;
9769	if (!EvaluateIntegerOrLValue(E: SubExpr, Result&: Value, Info))
9770	break;
9771
9772	if (Value.isInt()) {
9773	unsigned Size = Info.Ctx.getTypeSize(E->getType());
9774	uint64_t N = Value.getInt().extOrTrunc(width: Size).getZExtValue();
9775	Result.Base = (Expr*)nullptr;
9776	Result.InvalidBase = false;
9777	Result.Offset = CharUnits::fromQuantity(Quantity: N);
9778	Result.Designator.setInvalid();
9779	Result.IsNullPtr = false;
9780	return true;
9781	} else {
9782	// In rare instances, the value isn't an lvalue.
9783	// For example, when the value is the difference between the addresses of
9784	// two labels. We reject that as a constant expression because we can't
9785	// compute a valid offset to convert into a pointer.
9786	if (!Value.isLValue())
9787	return false;
9788
9789	// Cast is of an lvalue, no need to change value.
9790	Result.setFrom(Ctx&: Info.Ctx, V: Value);
9791	return true;
9792	}
9793	}
9794
9795	case CK_ArrayToPointerDecay: {
9796	if (SubExpr->isGLValue()) {
9797	if (!evaluateLValue(E: SubExpr, Result))
9798	return false;
9799	} else {
9800	APValue &Value = Info.CurrentCall->createTemporary(
9801	Key: SubExpr, T: SubExpr->getType(), Scope: ScopeKind::FullExpression, LV&: Result);
9802	if (!EvaluateInPlace(Result&: Value, Info, This: Result, E: SubExpr))
9803	return false;
9804	}
9805	// The result is a pointer to the first element of the array.
9806	auto *AT = Info.Ctx.getAsArrayType(T: SubExpr->getType());
9807	if (auto *CAT = dyn_cast<ConstantArrayType>(Val: AT))
9808	Result.addArray(Info, E, CAT);
9809	else
9810	Result.addUnsizedArray(Info, E, AT->getElementType());
9811	return true;
9812	}
9813
9814	case CK_FunctionToPointerDecay:
9815	return evaluateLValue(E: SubExpr, Result);
9816
9817	case CK_LValueToRValue: {
9818	LValue LVal;
9819	if (!evaluateLValue(E: E->getSubExpr(), Result&: LVal))
9820	return false;
9821
9822	APValue RVal;
9823	// Note, we use the subexpression's type in order to retain cv-qualifiers.
9824	if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
9825	LVal, RVal))
9826	return InvalidBaseOK &&
9827	evaluateLValueAsAllocSize(Info, Base: LVal.Base, Result);
9828	return Success(RVal, E);
9829	}
9830	}
9831
9832	return ExprEvaluatorBaseTy::VisitCastExpr(E);
9833	}
9834
9835	static CharUnits GetAlignOfType(const ASTContext &Ctx, QualType T,
9836	UnaryExprOrTypeTrait ExprKind) {
9837	// C++ [expr.alignof]p3:
9838	// When alignof is applied to a reference type, the result is the
9839	// alignment of the referenced type.
9840	T = T.getNonReferenceType();
9841
9842	if (T.getQualifiers().hasUnaligned())
9843	return CharUnits::One();
9844
9845	const bool AlignOfReturnsPreferred =
9846	Ctx.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver7;
9847
9848	// __alignof is defined to return the preferred alignment.
9849	// Before 8, clang returned the preferred alignment for alignof and _Alignof
9850	// as well.
9851	if (ExprKind == UETT_PreferredAlignOf || AlignOfReturnsPreferred)
9852	return Ctx.toCharUnitsFromBits(BitSize: Ctx.getPreferredTypeAlign(T: T.getTypePtr()));
9853	// alignof and _Alignof are defined to return the ABI alignment.
9854	else if (ExprKind == UETT_AlignOf)
9855	return Ctx.getTypeAlignInChars(T: T.getTypePtr());
9856	else
9857	llvm_unreachable("GetAlignOfType on a non-alignment ExprKind");
9858	}
9859
9860	CharUnits GetAlignOfExpr(const ASTContext &Ctx, const Expr *E,
9861	UnaryExprOrTypeTrait ExprKind) {
9862	E = E->IgnoreParens();
9863
9864	// The kinds of expressions that we have special-case logic here for
9865	// should be kept up to date with the special checks for those
9866	// expressions in Sema.
9867
9868	// alignof decl is always accepted, even if it doesn't make sense: we default
9869	// to 1 in those cases.
9870	if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Val: E))
9871	return Ctx.getDeclAlign(DRE->getDecl(),
9872	/*RefAsPointee*/ true);
9873
9874	if (const MemberExpr *ME = dyn_cast<MemberExpr>(Val: E))
9875	return Ctx.getDeclAlign(ME->getMemberDecl(),
9876	/*RefAsPointee*/ true);
9877
9878	return GetAlignOfType(Ctx, T: E->getType(), ExprKind);
9879	}
9880
9881	static CharUnits getBaseAlignment(EvalInfo &Info, const LValue &Value) {
9882	if (const auto *VD = Value.Base.dyn_cast<const ValueDecl *>())
9883	return Info.Ctx.getDeclAlign(VD);
9884	if (const auto *E = Value.Base.dyn_cast<const Expr *>())
9885	return GetAlignOfExpr(Ctx: Info.Ctx, E, ExprKind: UETT_AlignOf);
9886	return GetAlignOfType(Ctx: Info.Ctx, T: Value.Base.getTypeInfoType(), ExprKind: UETT_AlignOf);
9887	}
9888
9889	/// Evaluate the value of the alignment argument to __builtin_align_{up,down},
9890	/// __builtin_is_aligned and __builtin_assume_aligned.
9891	static bool getAlignmentArgument(const Expr *E, QualType ForType,
9892	EvalInfo &Info, APSInt &Alignment) {
9893	if (!EvaluateInteger(E, Result&: Alignment, Info))
9894	return false;
9895	if (Alignment < 0 || !Alignment.isPowerOf2()) {
9896	Info.FFDiag(E, diag::note_constexpr_invalid_alignment) << Alignment;
9897	return false;
9898	}
9899	unsigned SrcWidth = Info.Ctx.getIntWidth(T: ForType);
9900	APSInt MaxValue(APInt::getOneBitSet(numBits: SrcWidth, BitNo: SrcWidth - 1));
9901	if (APSInt::compareValues(I1: Alignment, I2: MaxValue) > 0) {
9902	Info.FFDiag(E, diag::note_constexpr_alignment_too_big)
9903	<< MaxValue << ForType << Alignment;
9904	return false;
9905	}
9906	// Ensure both alignment and source value have the same bit width so that we
9907	// don't assert when computing the resulting value.
9908	APSInt ExtAlignment =
9909	APSInt(Alignment.zextOrTrunc(width: SrcWidth), /*isUnsigned=*/true);
9910	assert(APSInt::compareValues(Alignment, ExtAlignment) == 0 &&
9911	"Alignment should not be changed by ext/trunc");
9912	Alignment = ExtAlignment;
9913	assert(Alignment.getBitWidth() == SrcWidth);
9914	return true;
9915	}
9916
9917	// To be clear: this happily visits unsupported builtins. Better name welcomed.
9918	bool PointerExprEvaluator::visitNonBuiltinCallExpr(const CallExpr *E) {
9919	if (ExprEvaluatorBaseTy::VisitCallExpr(E))
9920	return true;
9921
9922	if (!(InvalidBaseOK && getAllocSizeAttr(E)))
9923	return false;
9924
9925	Result.setInvalid(E);
9926	QualType PointeeTy = E->getType()->castAs<PointerType>()->getPointeeType();
9927	Result.addUnsizedArray(Info, E, PointeeTy);
9928	return true;
9929	}
9930
9931	bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) {
9932	if (!IsConstantEvaluatedBuiltinCall(E))
9933	return visitNonBuiltinCallExpr(E);
9934	return VisitBuiltinCallExpr(E, BuiltinOp: E->getBuiltinCallee());
9935	}
9936
9937	// Determine if T is a character type for which we guarantee that
9938	// sizeof(T) == 1.
9939	static bool isOneByteCharacterType(QualType T) {
9940	return T->isCharType() || T->isChar8Type();
9941	}
9942
9943	bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
9944	unsigned BuiltinOp) {
9945	if (IsOpaqueConstantCall(E))
9946	return Success(E);
9947
9948	switch (BuiltinOp) {
9949	case Builtin::BIaddressof:
9950	case Builtin::BI__addressof:
9951	case Builtin::BI__builtin_addressof:
9952	return evaluateLValue(E: E->getArg(Arg: 0), Result);
9953	case Builtin::BI__builtin_assume_aligned: {
9954	// We need to be very careful here because: if the pointer does not have the
9955	// asserted alignment, then the behavior is undefined, and undefined
9956	// behavior is non-constant.
9957	if (!evaluatePointer(E: E->getArg(Arg: 0), Result))
9958	return false;
9959
9960	LValue OffsetResult(Result);
9961	APSInt Alignment;
9962	if (!getAlignmentArgument(E: E->getArg(Arg: 1), ForType: E->getArg(Arg: 0)->getType(), Info,
9963	Alignment))
9964	return false;
9965	CharUnits Align = CharUnits::fromQuantity(Quantity: Alignment.getZExtValue());
9966
9967	if (E->getNumArgs() > 2) {
9968	APSInt Offset;
9969	if (!EvaluateInteger(E: E->getArg(Arg: 2), Result&: Offset, Info))
9970	return false;
9971
9972	int64_t AdditionalOffset = -Offset.getZExtValue();
9973	OffsetResult.Offset += CharUnits::fromQuantity(Quantity: AdditionalOffset);
9974	}
9975
9976	// If there is a base object, then it must have the correct alignment.
9977	if (OffsetResult.Base) {
9978	CharUnits BaseAlignment = getBaseAlignment(Info, Value: OffsetResult);
9979
9980	if (BaseAlignment < Align) {
9981	Result.Designator.setInvalid();
9982	CCEDiag(E->getArg(0), diag::note_constexpr_baa_insufficient_alignment)
9983	<< 0 << BaseAlignment.getQuantity() << Align.getQuantity();
9984	return false;
9985	}
9986	}
9987
9988	// The offset must also have the correct alignment.
9989	if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) {
9990	Result.Designator.setInvalid();
9991
9992	(OffsetResult.Base
9993	? CCEDiag(E->getArg(0),
9994	diag::note_constexpr_baa_insufficient_alignment)
9995	<< 1
9996	: CCEDiag(E->getArg(0),
9997	diag::note_constexpr_baa_value_insufficient_alignment))
9998	<< OffsetResult.Offset.getQuantity() << Align.getQuantity();
9999	return false;
10000	}
10001
10002	return true;
10003	}
10004	case Builtin::BI__builtin_align_up:
10005	case Builtin::BI__builtin_align_down: {
10006	if (!evaluatePointer(E: E->getArg(Arg: 0), Result))
10007	return false;
10008	APSInt Alignment;
10009	if (!getAlignmentArgument(E: E->getArg(Arg: 1), ForType: E->getArg(Arg: 0)->getType(), Info,
10010	Alignment))
10011	return false;
10012	CharUnits BaseAlignment = getBaseAlignment(Info, Value: Result);
10013	CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(offset: Result.Offset);
10014	// For align_up/align_down, we can return the same value if the alignment
10015	// is known to be greater or equal to the requested value.
10016	if (PtrAlign.getQuantity() >= Alignment)
10017	return true;
10018
10019	// The alignment could be greater than the minimum at run-time, so we cannot
10020	// infer much about the resulting pointer value. One case is possible:
10021	// For `_Alignas(32) char buf[N]; __builtin_align_down(&buf[idx], 32)` we
10022	// can infer the correct index if the requested alignment is smaller than
10023	// the base alignment so we can perform the computation on the offset.
10024	if (BaseAlignment.getQuantity() >= Alignment) {
10025	assert(Alignment.getBitWidth() <= 64 &&
10026	"Cannot handle > 64-bit address-space");
10027	uint64_t Alignment64 = Alignment.getZExtValue();
10028	CharUnits NewOffset = CharUnits::fromQuantity(
10029	BuiltinOp == Builtin::BI__builtin_align_down
10030	? llvm::alignDown(Result.Offset.getQuantity(), Alignment64)
10031	: llvm::alignTo(Result.Offset.getQuantity(), Alignment64));
10032	Result.adjustOffset(N: NewOffset - Result.Offset);
10033	// TODO: diagnose out-of-bounds values/only allow for arrays?
10034	return true;
10035	}
10036	// Otherwise, we cannot constant-evaluate the result.
10037	Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_adjust)
10038	<< Alignment;
10039	return false;
10040	}
10041	case Builtin::BI__builtin_operator_new:
10042	return HandleOperatorNewCall(Info, E, Result);
10043	case Builtin::BI__builtin_launder:
10044	return evaluatePointer(E: E->getArg(Arg: 0), Result);
10045	case Builtin::BIstrchr:
10046	case Builtin::BIwcschr:
10047	case Builtin::BImemchr:
10048	case Builtin::BIwmemchr:
10049	if (Info.getLangOpts().CPlusPlus11)
10050	Info.CCEDiag(E, diag::note_constexpr_invalid_function)
10051	<< /*isConstexpr*/ 0 << /*isConstructor*/ 0
10052	<< Info.Ctx.BuiltinInfo.getQuotedName(BuiltinOp);
10053	else
10054	Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
10055	[[fallthrough]];
10056	case Builtin::BI__builtin_strchr:
10057	case Builtin::BI__builtin_wcschr:
10058	case Builtin::BI__builtin_memchr:
10059	case Builtin::BI__builtin_char_memchr:
10060	case Builtin::BI__builtin_wmemchr: {
10061	if (!Visit(E->getArg(Arg: 0)))
10062	return false;
10063	APSInt Desired;
10064	if (!EvaluateInteger(E: E->getArg(Arg: 1), Result&: Desired, Info))
10065	return false;
10066	uint64_t MaxLength = uint64_t(-1);
10067	if (BuiltinOp != Builtin::BIstrchr &&
10068	BuiltinOp != Builtin::BIwcschr &&
10069	BuiltinOp != Builtin::BI__builtin_strchr &&
10070	BuiltinOp != Builtin::BI__builtin_wcschr) {
10071	APSInt N;
10072	if (!EvaluateInteger(E: E->getArg(Arg: 2), Result&: N, Info))
10073	return false;
10074	MaxLength = N.getZExtValue();
10075	}
10076	// We cannot find the value if there are no candidates to match against.
10077	if (MaxLength == 0u)
10078	return ZeroInitialization(E);
10079	if (!Result.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
10080	Result.Designator.Invalid)
10081	return false;
10082	QualType CharTy = Result.Designator.getType(Info.Ctx);
10083	bool IsRawByte = BuiltinOp == Builtin::BImemchr ||
10084	BuiltinOp == Builtin::BI__builtin_memchr;
10085	assert(IsRawByte ||
10086	Info.Ctx.hasSameUnqualifiedType(
10087	CharTy, E->getArg(0)->getType()->getPointeeType()));
10088	// Pointers to const void may point to objects of incomplete type.
10089	if (IsRawByte && CharTy->isIncompleteType()) {
10090	Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy;
10091	return false;
10092	}
10093	// Give up on byte-oriented matching against multibyte elements.
10094	// FIXME: We can compare the bytes in the correct order.
10095	if (IsRawByte && !isOneByteCharacterType(T: CharTy)) {
10096	Info.FFDiag(E, diag::note_constexpr_memchr_unsupported)
10097	<< Info.Ctx.BuiltinInfo.getQuotedName(BuiltinOp) << CharTy;
10098	return false;
10099	}
10100	// Figure out what value we're actually looking for (after converting to
10101	// the corresponding unsigned type if necessary).
10102	uint64_t DesiredVal;
10103	bool StopAtNull = false;
10104	switch (BuiltinOp) {
10105	case Builtin::BIstrchr:
10106	case Builtin::BI__builtin_strchr:
10107	// strchr compares directly to the passed integer, and therefore
10108	// always fails if given an int that is not a char.
10109	if (!APSInt::isSameValue(I1: HandleIntToIntCast(Info, E, CharTy,
10110	E->getArg(Arg: 1)->getType(),
10111	Desired),
10112	I2: Desired))
10113	return ZeroInitialization(E);
10114	StopAtNull = true;
10115	[[fallthrough]];
10116	case Builtin::BImemchr:
10117	case Builtin::BI__builtin_memchr:
10118	case Builtin::BI__builtin_char_memchr:
10119	// memchr compares by converting both sides to unsigned char. That's also
10120	// correct for strchr if we get this far (to cope with plain char being
10121	// unsigned in the strchr case).
10122	DesiredVal = Desired.trunc(width: Info.Ctx.getCharWidth()).getZExtValue();
10123	break;
10124
10125	case Builtin::BIwcschr:
10126	case Builtin::BI__builtin_wcschr:
10127	StopAtNull = true;
10128	[[fallthrough]];
10129	case Builtin::BIwmemchr:
10130	case Builtin::BI__builtin_wmemchr:
10131	// wcschr and wmemchr are given a wchar_t to look for. Just use it.
10132	DesiredVal = Desired.getZExtValue();
10133	break;
10134	}
10135
10136	for (; MaxLength; --MaxLength) {
10137	APValue Char;
10138	if (!handleLValueToRValueConversion(Info, E, CharTy, Result, Char) ||
10139	!Char.isInt())
10140	return false;
10141	if (Char.getInt().getZExtValue() == DesiredVal)
10142	return true;
10143	if (StopAtNull && !Char.getInt())
10144	break;
10145	if (!HandleLValueArrayAdjustment(Info, E, Result, CharTy, 1))
10146	return false;
10147	}
10148	// Not found: return nullptr.
10149	return ZeroInitialization(E);
10150	}
10151
10152	case Builtin::BImemcpy:
10153	case Builtin::BImemmove:
10154	case Builtin::BIwmemcpy:
10155	case Builtin::BIwmemmove:
10156	if (Info.getLangOpts().CPlusPlus11)
10157	Info.CCEDiag(E, diag::note_constexpr_invalid_function)
10158	<< /*isConstexpr*/ 0 << /*isConstructor*/ 0
10159	<< Info.Ctx.BuiltinInfo.getQuotedName(BuiltinOp);
10160	else
10161	Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
10162	[[fallthrough]];
10163	case Builtin::BI__builtin_memcpy:
10164	case Builtin::BI__builtin_memmove:
10165	case Builtin::BI__builtin_wmemcpy:
10166	case Builtin::BI__builtin_wmemmove: {
10167	bool WChar = BuiltinOp == Builtin::BIwmemcpy ||
10168	BuiltinOp == Builtin::BIwmemmove ||
10169	BuiltinOp == Builtin::BI__builtin_wmemcpy ||
10170	BuiltinOp == Builtin::BI__builtin_wmemmove;
10171	bool Move = BuiltinOp == Builtin::BImemmove ||
10172	BuiltinOp == Builtin::BIwmemmove ||
10173	BuiltinOp == Builtin::BI__builtin_memmove ||
10174	BuiltinOp == Builtin::BI__builtin_wmemmove;
10175
10176	// The result of mem* is the first argument.
10177	if (!Visit(E->getArg(Arg: 0)))
10178	return false;
10179	LValue Dest = Result;
10180
10181	LValue Src;
10182	if (!EvaluatePointer(E: E->getArg(Arg: 1), Result&: Src, Info))
10183	return false;
10184
10185	APSInt N;
10186	if (!EvaluateInteger(E: E->getArg(Arg: 2), Result&: N, Info))
10187	return false;
10188	assert(!N.isSigned() && "memcpy and friends take an unsigned size");
10189
10190	// If the size is zero, we treat this as always being a valid no-op.
10191	// (Even if one of the src and dest pointers is null.)
10192	if (!N)
10193	return true;
10194
10195	// Otherwise, if either of the operands is null, we can't proceed. Don't
10196	// try to determine the type of the copied objects, because there aren't
10197	// any.
10198	if (!Src.Base || !Dest.Base) {
10199	APValue Val;
10200	(!Src.Base ? Src : Dest).moveInto(V&: Val);
10201	Info.FFDiag(E, diag::note_constexpr_memcpy_null)
10202	<< Move << WChar << !!Src.Base
10203	<< Val.getAsString(Info.Ctx, E->getArg(0)->getType());
10204	return false;
10205	}
10206	if (Src.Designator.Invalid || Dest.Designator.Invalid)
10207	return false;
10208
10209	// We require that Src and Dest are both pointers to arrays of
10210	// trivially-copyable type. (For the wide version, the designator will be
10211	// invalid if the designated object is not a wchar_t.)
10212	QualType T = Dest.Designator.getType(Info.Ctx);
10213	QualType SrcT = Src.Designator.getType(Info.Ctx);
10214	if (!Info.Ctx.hasSameUnqualifiedType(T1: T, T2: SrcT)) {
10215	// FIXME: Consider using our bit_cast implementation to support this.
10216	Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move << SrcT << T;
10217	return false;
10218	}
10219	if (T->isIncompleteType()) {
10220	Info.FFDiag(E, diag::note_constexpr_memcpy_incomplete_type) << Move << T;
10221	return false;
10222	}
10223	if (!T.isTriviallyCopyableType(Context: Info.Ctx)) {
10224	Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move << T;
10225	return false;
10226	}
10227
10228	// Figure out how many T's we're copying.
10229	uint64_t TSize = Info.Ctx.getTypeSizeInChars(T).getQuantity();
10230	if (TSize == 0)
10231	return false;
10232	if (!WChar) {
10233	uint64_t Remainder;
10234	llvm::APInt OrigN = N;
10235	llvm::APInt::udivrem(LHS: OrigN, RHS: TSize, Quotient&: N, Remainder);
10236	if (Remainder) {
10237	Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
10238	<< Move << WChar << 0 << T << toString(OrigN, 10, /*Signed*/false)
10239	<< (unsigned)TSize;
10240	return false;
10241	}
10242	}
10243
10244	// Check that the copying will remain within the arrays, just so that we
10245	// can give a more meaningful diagnostic. This implicitly also checks that
10246	// N fits into 64 bits.
10247	uint64_t RemainingSrcSize = Src.Designator.validIndexAdjustments().second;
10248	uint64_t RemainingDestSize = Dest.Designator.validIndexAdjustments().second;
10249	if (N.ugt(RHS: RemainingSrcSize) || N.ugt(RHS: RemainingDestSize)) {
10250	Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
10251	<< Move << WChar << (N.ugt(RemainingSrcSize) ? 1 : 2) << T
10252	<< toString(N, 10, /*Signed*/false);
10253	return false;
10254	}
10255	uint64_t NElems = N.getZExtValue();
10256	uint64_t NBytes = NElems * TSize;
10257
10258	// Check for overlap.
10259	int Direction = 1;
10260	if (HasSameBase(A: Src, B: Dest)) {
10261	uint64_t SrcOffset = Src.getLValueOffset().getQuantity();
10262	uint64_t DestOffset = Dest.getLValueOffset().getQuantity();
10263	if (DestOffset >= SrcOffset && DestOffset - SrcOffset < NBytes) {
10264	// Dest is inside the source region.
10265	if (!Move) {
10266	Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
10267	return false;
10268	}
10269	// For memmove and friends, copy backwards.
10270	if (!HandleLValueArrayAdjustment(Info, E, Src, T, NElems - 1) ||
10271	!HandleLValueArrayAdjustment(Info, E, Dest, T, NElems - 1))
10272	return false;
10273	Direction = -1;
10274	} else if (!Move && SrcOffset >= DestOffset &&
10275	SrcOffset - DestOffset < NBytes) {
10276	// Src is inside the destination region for memcpy: invalid.
10277	Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
10278	return false;
10279	}
10280	}
10281
10282	while (true) {
10283	APValue Val;
10284	// FIXME: Set WantObjectRepresentation to true if we're copying a
10285	// char-like type?
10286	if (!handleLValueToRValueConversion(Info, E, T, Src, Val) ||
10287	!handleAssignment(Info, E, Dest, T, Val))
10288	return false;
10289	// Do not iterate past the last element; if we're copying backwards, that
10290	// might take us off the start of the array.
10291	if (--NElems == 0)
10292	return true;
10293	if (!HandleLValueArrayAdjustment(Info, E, Src, T, Direction) ||
10294	!HandleLValueArrayAdjustment(Info, E, Dest, T, Direction))
10295	return false;
10296	}
10297	}
10298
10299	default:
10300	return false;
10301	}
10302	}
10303
10304	static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This,
10305	APValue &Result, const InitListExpr *ILE,
10306	QualType AllocType);
10307	static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This,
10308	APValue &Result,
10309	const CXXConstructExpr *CCE,
10310	QualType AllocType);
10311
10312	bool PointerExprEvaluator::VisitCXXNewExpr(const CXXNewExpr *E) {
10313	if (!Info.getLangOpts().CPlusPlus20)
10314	Info.CCEDiag(E, diag::note_constexpr_new);
10315
10316	// We cannot speculatively evaluate a delete expression.
10317	if (Info.SpeculativeEvaluationDepth)
10318	return false;
10319
10320	FunctionDecl *OperatorNew = E->getOperatorNew();
10321	QualType AllocType = E->getAllocatedType();
10322	QualType TargetType = AllocType;
10323
10324	bool IsNothrow = false;
10325	bool IsPlacement = false;
10326
10327	if (E->getNumPlacementArgs() == 1 &&
10328	E->getPlacementArg(I: 0)->getType()->isNothrowT()) {
10329	// The only new-placement list we support is of the form (std::nothrow).
10330	//
10331	// FIXME: There is no restriction on this, but it's not clear that any
10332	// other form makes any sense. We get here for cases such as:
10333	//
10334	// new (std::align_val_t{N}) X(int)
10335	//
10336	// (which should presumably be valid only if N is a multiple of
10337	// alignof(int), and in any case can't be deallocated unless N is
10338	// alignof(X) and X has new-extended alignment).
10339	LValue Nothrow;
10340	if (!EvaluateLValue(E: E->getPlacementArg(I: 0), Result&: Nothrow, Info))
10341	return false;
10342	IsNothrow = true;
10343	} else if (OperatorNew->isReservedGlobalPlacementOperator()) {
10344	if (Info.CurrentCall->isStdFunction() || Info.getLangOpts().CPlusPlus26 ||
10345	(Info.CurrentCall->CanEvalMSConstexpr &&
10346	OperatorNew->hasAttr<MSConstexprAttr>())) {
10347	if (!EvaluatePointer(E: E->getPlacementArg(I: 0), Result, Info))
10348	return false;
10349	if (Result.Designator.Invalid)
10350	return false;
10351	TargetType = E->getPlacementArg(I: 0)->getType();
10352	IsPlacement = true;
10353	} else {
10354	Info.FFDiag(E, diag::note_constexpr_new_placement)
10355	<< /*C++26 feature*/ 1 << E->getSourceRange();
10356	return false;
10357	}
10358	} else if (E->getNumPlacementArgs()) {
10359	Info.FFDiag(E, diag::note_constexpr_new_placement)
10360	<< /*Unsupported*/ 0 << E->getSourceRange();
10361	return false;
10362	} else if (!OperatorNew
10363	->isUsableAsGlobalAllocationFunctionInConstantEvaluation()) {
10364	Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
10365	<< isa<CXXMethodDecl>(OperatorNew) << OperatorNew;
10366	return false;
10367	}
10368
10369	const Expr *Init = E->getInitializer();
10370	const InitListExpr *ResizedArrayILE = nullptr;
10371	const CXXConstructExpr *ResizedArrayCCE = nullptr;
10372	bool ValueInit = false;
10373
10374	if (std::optional<const Expr *> ArraySize = E->getArraySize()) {
10375	const Expr *Stripped = *ArraySize;
10376	for (; auto *ICE = dyn_cast<ImplicitCastExpr>(Val: Stripped);
10377	Stripped = ICE->getSubExpr())
10378	if (ICE->getCastKind() != CK_NoOp &&
10379	ICE->getCastKind() != CK_IntegralCast)
10380	break;
10381
10382	llvm::APSInt ArrayBound;
10383	if (!EvaluateInteger(E: Stripped, Result&: ArrayBound, Info))
10384	return false;
10385
10386	// C++ [expr.new]p9:
10387	// The expression is erroneous if:
10388	// -- [...] its value before converting to size_t [or] applying the
10389	// second standard conversion sequence is less than zero
10390	if (ArrayBound.isSigned() && ArrayBound.isNegative()) {
10391	if (IsNothrow)
10392	return ZeroInitialization(E);
10393
10394	Info.FFDiag(*ArraySize, diag::note_constexpr_new_negative)
10395	<< ArrayBound << (*ArraySize)->getSourceRange();
10396	return false;
10397	}
10398
10399	// -- its value is such that the size of the allocated object would
10400	// exceed the implementation-defined limit
10401	if (!Info.CheckArraySize(Loc: ArraySize.value()->getExprLoc(),
10402	BitWidth: ConstantArrayType::getNumAddressingBits(
10403	Context: Info.Ctx, ElementType: AllocType, NumElements: ArrayBound),
10404	ElemCount: ArrayBound.getZExtValue(), /*Diag=*/!IsNothrow)) {
10405	if (IsNothrow)
10406	return ZeroInitialization(E);
10407	return false;
10408	}
10409
10410	// -- the new-initializer is a braced-init-list and the number of
10411	// array elements for which initializers are provided [...]
10412	// exceeds the number of elements to initialize
10413	if (!Init) {
10414	// No initialization is performed.
10415	} else if (isa<CXXScalarValueInitExpr>(Val: Init) ||
10416	isa<ImplicitValueInitExpr>(Val: Init)) {
10417	ValueInit = true;
10418	} else if (auto *CCE = dyn_cast<CXXConstructExpr>(Val: Init)) {
10419	ResizedArrayCCE = CCE;
10420	} else {
10421	auto *CAT = Info.Ctx.getAsConstantArrayType(T: Init->getType());
10422	assert(CAT && "unexpected type for array initializer");
10423
10424	unsigned Bits =
10425	std::max(a: CAT->getSizeBitWidth(), b: ArrayBound.getBitWidth());
10426	llvm::APInt InitBound = CAT->getSize().zext(width: Bits);
10427	llvm::APInt AllocBound = ArrayBound.zext(width: Bits);
10428	if (InitBound.ugt(RHS: AllocBound)) {
10429	if (IsNothrow)
10430	return ZeroInitialization(E);
10431
10432	Info.FFDiag(*ArraySize, diag::note_constexpr_new_too_small)
10433	<< toString(AllocBound, 10, /*Signed=*/false)
10434	<< toString(InitBound, 10, /*Signed=*/false)
10435	<< (*ArraySize)->getSourceRange();
10436	return false;
10437	}
10438
10439	// If the sizes differ, we must have an initializer list, and we need
10440	// special handling for this case when we initialize.
10441	if (InitBound != AllocBound)
10442	ResizedArrayILE = cast<InitListExpr>(Val: Init);
10443	}
10444
10445	AllocType = Info.Ctx.getConstantArrayType(EltTy: AllocType, ArySize: ArrayBound, SizeExpr: nullptr,
10446	ASM: ArraySizeModifier::Normal, IndexTypeQuals: 0);
10447	} else {
10448	assert(!AllocType->isArrayType() &&
10449	"array allocation with non-array new");
10450	}
10451
10452	APValue *Val;
10453	if (IsPlacement) {
10454	AccessKinds AK = AK_Construct;
10455	struct FindObjectHandler {
10456	EvalInfo &Info;
10457	const Expr *E;
10458	QualType AllocType;
10459	const AccessKinds AccessKind;
10460	APValue *Value;
10461
10462	typedef bool result_type;
10463	bool failed() { return false; }
10464	bool checkConst(QualType QT) {
10465	if (QT.isConstQualified()) {
10466	Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
10467	return false;
10468	}
10469	return true;
10470	}
10471	bool found(APValue &Subobj, QualType SubobjType) {
10472	if (!checkConst(QT: SubobjType))
10473	return false;
10474	// FIXME: Reject the cases where [basic.life]p8 would not permit the
10475	// old name of the object to be used to name the new object.
10476	unsigned SubobjectSize = 1;
10477	unsigned AllocSize = 1;
10478	if (auto *CAT = dyn_cast<ConstantArrayType>(AllocType))
10479	AllocSize = CAT->getZExtSize();
10480	if (auto *CAT = dyn_cast<ConstantArrayType>(Val&: SubobjType))
10481	SubobjectSize = CAT->getZExtSize();
10482	if (SubobjectSize < AllocSize ||
10483	!Info.Ctx.hasSimilarType(Info.Ctx.getBaseElementType(SubobjType),
10484	Info.Ctx.getBaseElementType(AllocType))) {
10485	Info.FFDiag(E, diag::note_constexpr_placement_new_wrong_type)
10486	<< SubobjType << AllocType;
10487	return false;
10488	}
10489	Value = &Subobj;
10490	return true;
10491	}
10492	bool found(APSInt &Value, QualType SubobjType) {
10493	Info.FFDiag(E, diag::note_constexpr_construct_complex_elem);
10494	return false;
10495	}
10496	bool found(APFloat &Value, QualType SubobjType) {
10497	Info.FFDiag(E, diag::note_constexpr_construct_complex_elem);
10498	return false;
10499	}
10500	} Handler = {Info, E, AllocType, AK, nullptr};
10501
10502	CompleteObject Obj = findCompleteObject(Info, E, AK, Result, AllocType);
10503	if (!Obj || !findSubobject(Info, E, Obj, Result.Designator, Handler))
10504	return false;
10505
10506	Val = Handler.Value;
10507
10508	// [basic.life]p1:
10509	// The lifetime of an object o of type T ends when [...] the storage
10510	// which the object occupies is [...] reused by an object that is not
10511	// nested within o (6.6.2).
10512	*Val = APValue();
10513	} else {
10514	// Perform the allocation and obtain a pointer to the resulting object.
10515	Val = Info.createHeapAlloc(E, AllocType, Result);
10516	if (!Val)
10517	return false;
10518	}
10519
10520	if (ValueInit) {
10521	ImplicitValueInitExpr VIE(AllocType);
10522	if (!EvaluateInPlace(*Val, Info, Result, &VIE))
10523	return false;
10524	} else if (ResizedArrayILE) {
10525	if (!EvaluateArrayNewInitList(Info, This&: Result, Result&: *Val, ILE: ResizedArrayILE,
10526	AllocType))
10527	return false;
10528	} else if (ResizedArrayCCE) {
10529	if (!EvaluateArrayNewConstructExpr(Info, This&: Result, Result&: *Val, CCE: ResizedArrayCCE,
10530	AllocType))
10531	return false;
10532	} else if (Init) {
10533	if (!EvaluateInPlace(Result&: *Val, Info, This: Result, E: Init))
10534	return false;
10535	} else if (!handleDefaultInitValue(T: AllocType, Result&: *Val)) {
10536	return false;
10537	}
10538
10539	// Array new returns a pointer to the first element, not a pointer to the
10540	// array.
10541	if (auto *AT = AllocType->getAsArrayTypeUnsafe())
10542	Result.addArray(Info, E, CAT: cast<ConstantArrayType>(AT));
10543
10544	return true;
10545	}
10546	//===----------------------------------------------------------------------===//
10547	// Member Pointer Evaluation
10548	//===----------------------------------------------------------------------===//
10549
10550	namespace {
10551	class MemberPointerExprEvaluator
10552	: public ExprEvaluatorBase<MemberPointerExprEvaluator> {
10553	MemberPtr &Result;
10554
10555	bool Success(const ValueDecl *D) {
10556	Result = MemberPtr(D);
10557	return true;
10558	}
10559	public:
10560
10561	MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result)
10562	: ExprEvaluatorBaseTy(Info), Result(Result) {}
10563
10564	bool Success(const APValue &V, const Expr *E) {
10565	Result.setFrom(V);
10566	return true;
10567	}
10568	bool ZeroInitialization(const Expr *E) {
10569	return Success(D: (const ValueDecl*)nullptr);
10570	}
10571
10572	bool VisitCastExpr(const CastExpr *E);
10573	bool VisitUnaryAddrOf(const UnaryOperator *E);
10574	};
10575	} // end anonymous namespace
10576
10577	static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
10578	EvalInfo &Info) {
10579	assert(!E->isValueDependent());
10580	assert(E->isPRValue() && E->getType()->isMemberPointerType());
10581	return MemberPointerExprEvaluator(Info, Result).Visit(E);
10582	}
10583
10584	bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
10585	switch (E->getCastKind()) {
10586	default:
10587	return ExprEvaluatorBaseTy::VisitCastExpr(E);
10588
10589	case CK_NullToMemberPointer:
10590	VisitIgnoredValue(E: E->getSubExpr());
10591	return ZeroInitialization(E);
10592
10593	case CK_BaseToDerivedMemberPointer: {
10594	if (!Visit(E->getSubExpr()))
10595	return false;
10596	if (E->path_empty())
10597	return true;
10598	// Base-to-derived member pointer casts store the path in derived-to-base
10599	// order, so iterate backwards. The CXXBaseSpecifier also provides us with
10600	// the wrong end of the derived->base arc, so stagger the path by one class.
10601	typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter;
10602	for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin());
10603	PathI != PathE; ++PathI) {
10604	assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
10605	const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl();
10606	if (!Result.castToDerived(Derived))
10607	return Error(E);
10608	}
10609	if (!Result.castToDerived(Derived: E->getType()
10610	->castAs<MemberPointerType>()
10611	->getMostRecentCXXRecordDecl()))
10612	return Error(E);
10613	return true;
10614	}
10615
10616	case CK_DerivedToBaseMemberPointer:
10617	if (!Visit(E->getSubExpr()))
10618	return false;
10619	for (CastExpr::path_const_iterator PathI = E->path_begin(),
10620	PathE = E->path_end(); PathI != PathE; ++PathI) {
10621	assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
10622	const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
10623	if (!Result.castToBase(Base))
10624	return Error(E);
10625	}
10626	return true;
10627	}
10628	}
10629
10630	bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
10631	// C++11 [expr.unary.op]p3 has very strict rules on how the address of a
10632	// member can be formed.
10633	return Success(D: cast<DeclRefExpr>(Val: E->getSubExpr())->getDecl());
10634	}
10635
10636	//===----------------------------------------------------------------------===//
10637	// Record Evaluation
10638	//===----------------------------------------------------------------------===//
10639
10640	namespace {
10641	class RecordExprEvaluator
10642	: public ExprEvaluatorBase<RecordExprEvaluator> {
10643	const LValue &This;
10644	APValue &Result;
10645	public:
10646
10647	RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result)
10648	: ExprEvaluatorBaseTy(info), This(This), Result(Result) {}
10649
10650	bool Success(const APValue &V, const Expr *E) {
10651	Result = V;
10652	return true;
10653	}
10654	bool ZeroInitialization(const Expr *E) {
10655	return ZeroInitialization(E, T: E->getType());
10656	}
10657	bool ZeroInitialization(const Expr *E, QualType T);
10658
10659	bool VisitCallExpr(const CallExpr *E) {
10660	return handleCallExpr(E, Result, ResultSlot: &This);
10661	}
10662	bool VisitCastExpr(const CastExpr *E);
10663	bool VisitInitListExpr(const InitListExpr *E);
10664	bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
10665	return VisitCXXConstructExpr(E, E->getType());
10666	}
10667	bool VisitLambdaExpr(const LambdaExpr *E);
10668	bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E);
10669	bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T);
10670	bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E);
10671	bool VisitBinCmp(const BinaryOperator *E);
10672	bool VisitCXXParenListInitExpr(const CXXParenListInitExpr *E);
10673	bool VisitCXXParenListOrInitListExpr(const Expr *ExprToVisit,
10674	ArrayRef<Expr *> Args);
10675	};
10676	}
10677
10678	/// Perform zero-initialization on an object of non-union class type.
10679	/// C++11 [dcl.init]p5:
10680	/// To zero-initialize an object or reference of type T means:
10681	/// [...]
10682	/// -- if T is a (possibly cv-qualified) non-union class type,
10683	/// each non-static data member and each base-class subobject is
10684	/// zero-initialized
10685	static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E,
10686	const RecordDecl *RD,
10687	const LValue &This, APValue &Result) {
10688	assert(!RD->isUnion() && "Expected non-union class type");
10689	const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(Val: RD);
10690	Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0,
10691	std::distance(first: RD->field_begin(), last: RD->field_end()));
10692
10693	if (RD->isInvalidDecl()) return false;
10694	const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(D: RD);
10695
10696	if (CD) {
10697	unsigned Index = 0;
10698	for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(),
10699	End = CD->bases_end(); I != End; ++I, ++Index) {
10700	const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl();
10701	LValue Subobject = This;
10702	if (!HandleLValueDirectBase(Info, E, Obj&: Subobject, Derived: CD, Base, RL: &Layout))
10703	return false;
10704	if (!HandleClassZeroInitialization(Info, E, Base, Subobject,
10705	Result.getStructBase(i: Index)))
10706	return false;
10707	}
10708	}
10709
10710	for (const auto *I : RD->fields()) {
10711	// -- if T is a reference type, no initialization is performed.
10712	if (I->isUnnamedBitField() || I->getType()->isReferenceType())
10713	continue;
10714
10715	LValue Subobject = This;
10716	if (!HandleLValueMember(Info, E, LVal&: Subobject, FD: I, RL: &Layout))
10717	return false;
10718
10719	ImplicitValueInitExpr VIE(I->getType());
10720	if (!EvaluateInPlace(
10721	Result.getStructField(i: I->getFieldIndex()), Info, Subobject, &VIE))
10722	return false;
10723	}
10724
10725	return true;
10726	}
10727
10728	bool RecordExprEvaluator::ZeroInitialization(const Expr *E, QualType T) {
10729	const RecordDecl *RD = T->castAs<RecordType>()->getDecl();
10730	if (RD->isInvalidDecl()) return false;
10731	if (RD->isUnion()) {
10732	// C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the
10733	// object's first non-static named data member is zero-initialized
10734	RecordDecl::field_iterator I = RD->field_begin();
10735	while (I != RD->field_end() && (*I)->isUnnamedBitField())
10736	++I;
10737	if (I == RD->field_end()) {
10738	Result = APValue((const FieldDecl*)nullptr);
10739	return true;
10740	}
10741
10742	LValue Subobject = This;
10743	if (!HandleLValueMember(Info, E, LVal&: Subobject, FD: *I))
10744	return false;
10745	Result = APValue(*I);
10746	ImplicitValueInitExpr VIE(I->getType());
10747	return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE);
10748	}
10749
10750	if (isa<CXXRecordDecl>(Val: RD) && cast<CXXRecordDecl>(Val: RD)->getNumVBases()) {
10751	Info.FFDiag(E, diag::note_constexpr_virtual_base) << RD;
10752	return false;
10753	}
10754
10755	return HandleClassZeroInitialization(Info, E, RD, This, Result);
10756	}
10757
10758	bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) {
10759	switch (E->getCastKind()) {
10760	default:
10761	return ExprEvaluatorBaseTy::VisitCastExpr(E);
10762
10763	case CK_ConstructorConversion:
10764	return Visit(E->getSubExpr());
10765
10766	case CK_DerivedToBase:
10767	case CK_UncheckedDerivedToBase: {
10768	APValue DerivedObject;
10769	if (!Evaluate(Result&: DerivedObject, Info, E: E->getSubExpr()))
10770	return false;
10771	if (!DerivedObject.isStruct())
10772	return Error(E: E->getSubExpr());
10773
10774	// Derived-to-base rvalue conversion: just slice off the derived part.
10775	APValue *Value = &DerivedObject;
10776	const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl();
10777	for (CastExpr::path_const_iterator PathI = E->path_begin(),
10778	PathE = E->path_end(); PathI != PathE; ++PathI) {
10779	assert(!(*PathI)->isVirtual() && "record rvalue with virtual base");
10780	const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
10781	Value = &Value->getStructBase(i: getBaseIndex(Derived: RD, Base));
10782	RD = Base;
10783	}
10784	Result = *Value;
10785	return true;
10786	}
10787	}
10788	}
10789
10790	bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
10791	if (E->isTransparent())
10792	return Visit(E->getInit(Init: 0));
10793	return VisitCXXParenListOrInitListExpr(E, E->inits());
10794	}
10795
10796	bool RecordExprEvaluator::VisitCXXParenListOrInitListExpr(
10797	const Expr *ExprToVisit, ArrayRef<Expr *> Args) {
10798	const RecordDecl *RD =
10799	ExprToVisit->getType()->castAs<RecordType>()->getDecl();
10800	if (RD->isInvalidDecl()) return false;
10801	const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(D: RD);
10802	auto *CXXRD = dyn_cast<CXXRecordDecl>(Val: RD);
10803
10804	EvalInfo::EvaluatingConstructorRAII EvalObj(
10805	Info,
10806	ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
10807	CXXRD && CXXRD->getNumBases());
10808
10809	if (RD->isUnion()) {
10810	const FieldDecl *Field;
10811	if (auto *ILE = dyn_cast<InitListExpr>(Val: ExprToVisit)) {
10812	Field = ILE->getInitializedFieldInUnion();
10813	} else if (auto *PLIE = dyn_cast<CXXParenListInitExpr>(Val: ExprToVisit)) {
10814	Field = PLIE->getInitializedFieldInUnion();
10815	} else {
10816	llvm_unreachable(
10817	"Expression is neither an init list nor a C++ paren list");
10818	}
10819
10820	Result = APValue(Field);
10821	if (!Field)
10822	return true;
10823
10824	// If the initializer list for a union does not contain any elements, the
10825	// first element of the union is value-initialized.
10826	// FIXME: The element should be initialized from an initializer list.
10827	// Is this difference ever observable for initializer lists which
10828	// we don't build?
10829	ImplicitValueInitExpr VIE(Field->getType());
10830	const Expr *InitExpr = Args.empty() ? &VIE : Args[0];
10831
10832	LValue Subobject = This;
10833	if (!HandleLValueMember(Info, E: InitExpr, LVal&: Subobject, FD: Field, RL: &Layout))
10834	return false;
10835
10836	// Temporarily override This, in case there's a CXXDefaultInitExpr in here.
10837	ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
10838	isa<CXXDefaultInitExpr>(Val: InitExpr));
10839
10840	if (EvaluateInPlace(Result&: Result.getUnionValue(), Info, This: Subobject, E: InitExpr)) {
10841	if (Field->isBitField())
10842	return truncateBitfieldValue(Info, E: InitExpr, Value&: Result.getUnionValue(),
10843	FD: Field);
10844	return true;
10845	}
10846
10847	return false;
10848	}
10849
10850	if (!Result.hasValue())
10851	Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0,
10852	std::distance(first: RD->field_begin(), last: RD->field_end()));
10853	unsigned ElementNo = 0;
10854	bool Success = true;
10855
10856	// Initialize base classes.
10857	if (CXXRD && CXXRD->getNumBases()) {
10858	for (const auto &Base : CXXRD->bases()) {
10859	assert(ElementNo < Args.size() && "missing init for base class");
10860	const Expr *Init = Args[ElementNo];
10861
10862	LValue Subobject = This;
10863	if (!HandleLValueBase(Info, E: Init, Obj&: Subobject, DerivedDecl: CXXRD, Base: &Base))
10864	return false;
10865
10866	APValue &FieldVal = Result.getStructBase(i: ElementNo);
10867	if (!EvaluateInPlace(Result&: FieldVal, Info, This: Subobject, E: Init)) {
10868	if (!Info.noteFailure())
10869	return false;
10870	Success = false;
10871	}
10872	++ElementNo;
10873	}
10874
10875	EvalObj.finishedConstructingBases();
10876	}
10877
10878	// Initialize members.
10879	for (const auto *Field : RD->fields()) {
10880	// Anonymous bit-fields are not considered members of the class for
10881	// purposes of aggregate initialization.
10882	if (Field->isUnnamedBitField())
10883	continue;
10884
10885	LValue Subobject = This;
10886
10887	bool HaveInit = ElementNo < Args.size();
10888
10889	// FIXME: Diagnostics here should point to the end of the initializer
10890	// list, not the start.
10891	if (!HandleLValueMember(Info, E: HaveInit ? Args[ElementNo] : ExprToVisit,
10892	LVal&: Subobject, FD: Field, RL: &Layout))
10893	return false;
10894
10895	// Perform an implicit value-initialization for members beyond the end of
10896	// the initializer list.
10897	ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType());
10898	const Expr *Init = HaveInit ? Args[ElementNo++] : &VIE;
10899
10900	if (Field->getType()->isIncompleteArrayType()) {
10901	if (auto *CAT = Info.Ctx.getAsConstantArrayType(Init->getType())) {
10902	if (!CAT->isZeroSize()) {
10903	// Bail out for now. This might sort of "work", but the rest of the
10904	// code isn't really prepared to handle it.
10905	Info.FFDiag(Init, diag::note_constexpr_unsupported_flexible_array);
10906	return false;
10907	}
10908	}
10909	}
10910
10911	// Temporarily override This, in case there's a CXXDefaultInitExpr in here.
10912	ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
10913	isa<CXXDefaultInitExpr>(Val: Init));
10914
10915	APValue &FieldVal = Result.getStructField(i: Field->getFieldIndex());
10916	if (!EvaluateInPlace(Result&: FieldVal, Info, This: Subobject, E: Init) ||
10917	(Field->isBitField() && !truncateBitfieldValue(Info, E: Init,
10918	Value&: FieldVal, FD: Field))) {
10919	if (!Info.noteFailure())
10920	return false;
10921	Success = false;
10922	}
10923	}
10924
10925	EvalObj.finishedConstructingFields();
10926
10927	return Success;
10928	}
10929
10930	bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
10931	QualType T) {
10932	// Note that E's type is not necessarily the type of our class here; we might
10933	// be initializing an array element instead.
10934	const CXXConstructorDecl *FD = E->getConstructor();
10935	if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false;
10936
10937	bool ZeroInit = E->requiresZeroInitialization();
10938	if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) {
10939	// If we've already performed zero-initialization, we're already done.
10940	if (Result.hasValue())
10941	return true;
10942
10943	if (ZeroInit)
10944	return ZeroInitialization(E, T);
10945
10946	return handleDefaultInitValue(T, Result);
10947	}
10948
10949	const FunctionDecl *Definition = nullptr;
10950	auto Body = FD->getBody(Definition);
10951
10952	if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
10953	return false;
10954
10955	// Avoid materializing a temporary for an elidable copy/move constructor.
10956	if (E->isElidable() && !ZeroInit) {
10957	// FIXME: This only handles the simplest case, where the source object
10958	// is passed directly as the first argument to the constructor.
10959	// This should also handle stepping though implicit casts and
10960	// and conversion sequences which involve two steps, with a
10961	// conversion operator followed by a converting constructor.
10962	const Expr *SrcObj = E->getArg(Arg: 0);
10963	assert(SrcObj->isTemporaryObject(Info.Ctx, FD->getParent()));
10964	assert(Info.Ctx.hasSameUnqualifiedType(E->getType(), SrcObj->getType()));
10965	if (const MaterializeTemporaryExpr *ME =
10966	dyn_cast<MaterializeTemporaryExpr>(Val: SrcObj))
10967	return Visit(ME->getSubExpr());
10968	}
10969
10970	if (ZeroInit && !ZeroInitialization(E, T))
10971	return false;
10972
10973	auto Args = llvm::ArrayRef(E->getArgs(), E->getNumArgs());
10974	return HandleConstructorCall(E, This, Args,
10975	cast<CXXConstructorDecl>(Val: Definition), Info,
10976	Result);
10977	}
10978
10979	bool RecordExprEvaluator::VisitCXXInheritedCtorInitExpr(
10980	const CXXInheritedCtorInitExpr *E) {
10981	if (!Info.CurrentCall) {
10982	assert(Info.checkingPotentialConstantExpression());
10983	return false;
10984	}
10985
10986	const CXXConstructorDecl *FD = E->getConstructor();
10987	if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl())
10988	return false;
10989
10990	const FunctionDecl *Definition = nullptr;
10991	auto Body = FD->getBody(Definition);
10992
10993	if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
10994	return false;
10995
10996	return HandleConstructorCall(E, This, Info.CurrentCall->Arguments,
10997	cast<CXXConstructorDecl>(Val: Definition), Info,
10998	Result);
10999	}
11000
11001	bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
11002	const CXXStdInitializerListExpr *E) {
11003	const ConstantArrayType *ArrayType =
11004	Info.Ctx.getAsConstantArrayType(T: E->getSubExpr()->getType());
11005
11006	LValue Array;
11007	if (!EvaluateLValue(E: E->getSubExpr(), Result&: Array, Info))
11008	return false;
11009
11010	assert(ArrayType && "unexpected type for array initializer");
11011
11012	// Get a pointer to the first element of the array.
11013	Array.addArray(Info, E, ArrayType);
11014
11015	// FIXME: What if the initializer_list type has base classes, etc?
11016	Result = APValue(APValue::UninitStruct(), 0, 2);
11017	Array.moveInto(V&: Result.getStructField(i: 0));
11018
11019	RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
11020	RecordDecl::field_iterator Field = Record->field_begin();
11021	assert(Field != Record->field_end() &&
11022	Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
11023	ArrayType->getElementType()) &&
11024	"Expected std::initializer_list first field to be const E *");
11025	++Field;
11026	assert(Field != Record->field_end() &&
11027	"Expected std::initializer_list to have two fields");
11028
11029	if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType())) {
11030	// Length.
11031	Result.getStructField(i: 1) = APValue(APSInt(ArrayType->getSize()));
11032	} else {
11033	// End pointer.
11034	assert(Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
11035	ArrayType->getElementType()) &&
11036	"Expected std::initializer_list second field to be const E *");
11037	if (!HandleLValueArrayAdjustment(Info, E, Array,
11038	ArrayType->getElementType(),
11039	ArrayType->getZExtSize()))
11040	return false;
11041	Array.moveInto(V&: Result.getStructField(i: 1));
11042	}
11043
11044	assert(++Field == Record->field_end() &&
11045	"Expected std::initializer_list to only have two fields");
11046
11047	return true;
11048	}
11049
11050	bool RecordExprEvaluator::VisitLambdaExpr(const LambdaExpr *E) {
11051	const CXXRecordDecl *ClosureClass = E->getLambdaClass();
11052	if (ClosureClass->isInvalidDecl())
11053	return false;
11054
11055	const size_t NumFields =
11056	std::distance(ClosureClass->field_begin(), ClosureClass->field_end());
11057
11058	assert(NumFields == (size_t)std::distance(E->capture_init_begin(),
11059	E->capture_init_end()) &&
11060	"The number of lambda capture initializers should equal the number of "
11061	"fields within the closure type");
11062
11063	Result = APValue(APValue::UninitStruct(), /*NumBases*/0, NumFields);
11064	// Iterate through all the lambda's closure object's fields and initialize
11065	// them.
11066	auto *CaptureInitIt = E->capture_init_begin();
11067	bool Success = true;
11068	const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(ClosureClass);
11069	for (const auto *Field : ClosureClass->fields()) {
11070	assert(CaptureInitIt != E->capture_init_end());
11071	// Get the initializer for this field
11072	Expr *const CurFieldInit = *CaptureInitIt++;
11073
11074	// If there is no initializer, either this is a VLA or an error has
11075	// occurred.
11076	if (!CurFieldInit || CurFieldInit->containsErrors())
11077	return Error(E);
11078
11079	LValue Subobject = This;
11080
11081	if (!HandleLValueMember(Info, E, Subobject, Field, &Layout))
11082	return false;
11083
11084	APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
11085	if (!EvaluateInPlace(FieldVal, Info, Subobject, CurFieldInit)) {
11086	if (!Info.keepEvaluatingAfterFailure())
11087	return false;
11088	Success = false;
11089	}
11090	}
11091	return Success;
11092	}
11093
11094	static bool EvaluateRecord(const Expr *E, const LValue &This,
11095	APValue &Result, EvalInfo &Info) {
11096	assert(!E->isValueDependent());
11097	assert(E->isPRValue() && E->getType()->isRecordType() &&
11098	"can't evaluate expression as a record rvalue");
11099	return RecordExprEvaluator(Info, This, Result).Visit(E);
11100	}
11101
11102	//===----------------------------------------------------------------------===//
11103	// Temporary Evaluation
11104	//
11105	// Temporaries are represented in the AST as rvalues, but generally behave like
11106	// lvalues. The full-object of which the temporary is a subobject is implicitly
11107	// materialized so that a reference can bind to it.
11108	//===----------------------------------------------------------------------===//
11109	namespace {
11110	class TemporaryExprEvaluator
11111	: public LValueExprEvaluatorBase<TemporaryExprEvaluator> {
11112	public:
11113	TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) :
11114	LValueExprEvaluatorBaseTy(Info, Result, false) {}
11115
11116	/// Visit an expression which constructs the value of this temporary.
11117	bool VisitConstructExpr(const Expr *E) {
11118	APValue &Value = Info.CurrentCall->createTemporary(
11119	Key: E, T: E->getType(), Scope: ScopeKind::FullExpression, LV&: Result);
11120	return EvaluateInPlace(Result&: Value, Info, This: Result, E);
11121	}
11122
11123	bool VisitCastExpr(const CastExpr *E) {
11124	switch (E->getCastKind()) {
11125	default:
11126	return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
11127
11128	case CK_ConstructorConversion:
11129	return VisitConstructExpr(E: E->getSubExpr());
11130	}
11131	}
11132	bool VisitInitListExpr(const InitListExpr *E) {
11133	return VisitConstructExpr(E);
11134	}
11135	bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
11136	return VisitConstructExpr(E);
11137	}
11138	bool VisitCallExpr(const CallExpr *E) {
11139	return VisitConstructExpr(E);
11140	}
11141	bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) {
11142	return VisitConstructExpr(E);
11143	}
11144	bool VisitLambdaExpr(const LambdaExpr *E) {
11145	return VisitConstructExpr(E);
11146	}
11147	};
11148	} // end anonymous namespace
11149
11150	/// Evaluate an expression of record type as a temporary.
11151	static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) {
11152	assert(!E->isValueDependent());
11153	assert(E->isPRValue() && E->getType()->isRecordType());
11154	return TemporaryExprEvaluator(Info, Result).Visit(E);
11155	}
11156
11157	//===----------------------------------------------------------------------===//
11158	// Vector Evaluation
11159	//===----------------------------------------------------------------------===//
11160
11161	namespace {
11162	class VectorExprEvaluator
11163	: public ExprEvaluatorBase<VectorExprEvaluator> {
11164	APValue &Result;
11165	public:
11166
11167	VectorExprEvaluator(EvalInfo &info, APValue &Result)
11168	: ExprEvaluatorBaseTy(info), Result(Result) {}
11169
11170	bool Success(ArrayRef<APValue> V, const Expr *E) {
11171	assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements());
11172	// FIXME: remove this APValue copy.
11173	Result = APValue(V.data(), V.size());
11174	return true;
11175	}
11176	bool Success(const APValue &V, const Expr *E) {
11177	assert(V.isVector());
11178	Result = V;
11179	return true;
11180	}
11181	bool ZeroInitialization(const Expr *E);
11182
11183	bool VisitUnaryReal(const UnaryOperator *E)
11184	{ return Visit(E->getSubExpr()); }
11185	bool VisitCastExpr(const CastExpr* E);
11186	bool VisitInitListExpr(const InitListExpr *E);
11187	bool VisitUnaryImag(const UnaryOperator *E);
11188	bool VisitBinaryOperator(const BinaryOperator *E);
11189	bool VisitUnaryOperator(const UnaryOperator *E);
11190	bool VisitCallExpr(const CallExpr *E);
11191	bool VisitConvertVectorExpr(const ConvertVectorExpr *E);
11192	bool VisitShuffleVectorExpr(const ShuffleVectorExpr *E);
11193
11194	// FIXME: Missing: conditional operator (for GNU
11195	// conditional select), ExtVectorElementExpr
11196	};
11197	} // end anonymous namespace
11198
11199	static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) {
11200	assert(E->isPRValue() && E->getType()->isVectorType() &&
11201	"not a vector prvalue");
11202	return VectorExprEvaluator(Info, Result).Visit(E);
11203	}
11204
11205	bool VectorExprEvaluator::VisitCastExpr(const CastExpr *E) {
11206	const VectorType *VTy = E->getType()->castAs<VectorType>();
11207	unsigned NElts = VTy->getNumElements();
11208
11209	const Expr *SE = E->getSubExpr();
11210	QualType SETy = SE->getType();
11211
11212	switch (E->getCastKind()) {
11213	case CK_VectorSplat: {
11214	APValue Val = APValue();
11215	if (SETy->isIntegerType()) {
11216	APSInt IntResult;
11217	if (!EvaluateInteger(E: SE, Result&: IntResult, Info))
11218	return false;
11219	Val = APValue(std::move(IntResult));
11220	} else if (SETy->isRealFloatingType()) {
11221	APFloat FloatResult(0.0);
11222	if (!EvaluateFloat(E: SE, Result&: FloatResult, Info))
11223	return false;
11224	Val = APValue(std::move(FloatResult));
11225	} else {
11226	return Error(E);
11227	}
11228
11229	// Splat and create vector APValue.
11230	SmallVector<APValue, 4> Elts(NElts, Val);
11231	return Success(Elts, E);
11232	}
11233	case CK_BitCast: {
11234	APValue SVal;
11235	if (!Evaluate(Result&: SVal, Info, E: SE))
11236	return false;
11237
11238	if (!SVal.isInt() && !SVal.isFloat() && !SVal.isVector()) {
11239	// Give up if the input isn't an int, float, or vector. For example, we
11240	// reject "(v4i16)(intptr_t)&a".
11241	Info.FFDiag(E, diag::note_constexpr_invalid_cast)
11242	<< diag::ConstexprInvalidCastKind::ThisConversionOrReinterpret
11243	<< Info.Ctx.getLangOpts().CPlusPlus;
11244	return false;
11245	}
11246
11247	if (!handleRValueToRValueBitCast(Info, DestValue&: Result, SourceRValue: SVal, BCE: E))
11248	return false;
11249
11250	return true;
11251	}
11252	case CK_HLSLVectorTruncation: {
11253	APValue Val;
11254	SmallVector<APValue, 4> Elements;
11255	if (!EvaluateVector(E: SE, Result&: Val, Info))
11256	return Error(E);
11257	for (unsigned I = 0; I < NElts; I++)
11258	Elements.push_back(Elt: Val.getVectorElt(I));
11259	return Success(Elements, E);
11260	}
11261	default:
11262	return ExprEvaluatorBaseTy::VisitCastExpr(E);
11263	}
11264	}
11265
11266	bool
11267	VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
11268	const VectorType *VT = E->getType()->castAs<VectorType>();
11269	unsigned NumInits = E->getNumInits();
11270	unsigned NumElements = VT->getNumElements();
11271
11272	QualType EltTy = VT->getElementType();
11273	SmallVector<APValue, 4> Elements;
11274
11275	// MFloat8 type doesn't have constants and thus constant folding
11276	// is impossible.
11277	if (EltTy->isMFloat8Type())
11278	return false;
11279
11280	// The number of initializers can be less than the number of
11281	// vector elements. For OpenCL, this can be due to nested vector
11282	// initialization. For GCC compatibility, missing trailing elements
11283	// should be initialized with zeroes.
11284	unsigned CountInits = 0, CountElts = 0;
11285	while (CountElts < NumElements) {
11286	// Handle nested vector initialization.
11287	if (CountInits < NumInits
11288	&& E->getInit(Init: CountInits)->getType()->isVectorType()) {
11289	APValue v;
11290	if (!EvaluateVector(E: E->getInit(Init: CountInits), Result&: v, Info))
11291	return Error(E);
11292	unsigned vlen = v.getVectorLength();
11293	for (unsigned j = 0; j < vlen; j++)
11294	Elements.push_back(Elt: v.getVectorElt(I: j));
11295	CountElts += vlen;
11296	} else if (EltTy->isIntegerType()) {
11297	llvm::APSInt sInt(32);
11298	if (CountInits < NumInits) {
11299	if (!EvaluateInteger(E: E->getInit(Init: CountInits), Result&: sInt, Info))
11300	return false;
11301	} else // trailing integer zero.
11302	sInt = Info.Ctx.MakeIntValue(Value: 0, Type: EltTy);
11303	Elements.push_back(Elt: APValue(sInt));
11304	CountElts++;
11305	} else {
11306	llvm::APFloat f(0.0);
11307	if (CountInits < NumInits) {
11308	if (!EvaluateFloat(E: E->getInit(Init: CountInits), Result&: f, Info))
11309	return false;
11310	} else // trailing float zero.
11311	f = APFloat::getZero(Sem: Info.Ctx.getFloatTypeSemantics(T: EltTy));
11312	Elements.push_back(Elt: APValue(f));
11313	CountElts++;
11314	}
11315	CountInits++;
11316	}
11317	return Success(Elements, E);
11318	}
11319
11320	bool
11321	VectorExprEvaluator::ZeroInitialization(const Expr *E) {
11322	const auto *VT = E->getType()->castAs<VectorType>();
11323	QualType EltTy = VT->getElementType();
11324	APValue ZeroElement;
11325	if (EltTy->isIntegerType())
11326	ZeroElement = APValue(Info.Ctx.MakeIntValue(Value: 0, Type: EltTy));
11327	else
11328	ZeroElement =
11329	APValue(APFloat::getZero(Sem: Info.Ctx.getFloatTypeSemantics(T: EltTy)));
11330
11331	SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement);
11332	return Success(V: Elements, E);
11333	}
11334
11335	bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
11336	VisitIgnoredValue(E: E->getSubExpr());
11337	return ZeroInitialization(E);
11338	}
11339
11340	bool VectorExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
11341	BinaryOperatorKind Op = E->getOpcode();
11342	assert(Op != BO_PtrMemD && Op != BO_PtrMemI && Op != BO_Cmp &&
11343	"Operation not supported on vector types");
11344
11345	if (Op == BO_Comma)
11346	return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
11347
11348	Expr *LHS = E->getLHS();
11349	Expr *RHS = E->getRHS();
11350
11351	assert(LHS->getType()->isVectorType() && RHS->getType()->isVectorType() &&
11352	"Must both be vector types");
11353	// Checking JUST the types are the same would be fine, except shifts don't
11354	// need to have their types be the same (since you always shift by an int).
11355	assert(LHS->getType()->castAs<VectorType>()->getNumElements() ==
11356	E->getType()->castAs<VectorType>()->getNumElements() &&
11357	RHS->getType()->castAs<VectorType>()->getNumElements() ==
11358	E->getType()->castAs<VectorType>()->getNumElements() &&
11359	"All operands must be the same size.");
11360
11361	APValue LHSValue;
11362	APValue RHSValue;
11363	bool LHSOK = Evaluate(Result&: LHSValue, Info, E: LHS);
11364	if (!LHSOK && !Info.noteFailure())
11365	return false;
11366	if (!Evaluate(Result&: RHSValue, Info, E: RHS) || !LHSOK)
11367	return false;
11368
11369	if (!handleVectorVectorBinOp(Info, E, Opcode: Op, LHSValue, RHSValue))
11370	return false;
11371
11372	return Success(LHSValue, E);
11373	}
11374
11375	static std::optional<APValue> handleVectorUnaryOperator(ASTContext &Ctx,
11376	QualType ResultTy,
11377	UnaryOperatorKind Op,
11378	APValue Elt) {
11379	switch (Op) {
11380	case UO_Plus:
11381	// Nothing to do here.
11382	return Elt;
11383	case UO_Minus:
11384	if (Elt.getKind() == APValue::Int) {
11385	Elt.getInt().negate();
11386	} else {
11387	assert(Elt.getKind() == APValue::Float &&
11388	"Vector can only be int or float type");
11389	Elt.getFloat().changeSign();
11390	}
11391	return Elt;
11392	case UO_Not:
11393	// This is only valid for integral types anyway, so we don't have to handle
11394	// float here.
11395	assert(Elt.getKind() == APValue::Int &&
11396	"Vector operator ~ can only be int");
11397	Elt.getInt().flipAllBits();
11398	return Elt;
11399	case UO_LNot: {
11400	if (Elt.getKind() == APValue::Int) {
11401	Elt.getInt() = !Elt.getInt();
11402	// operator ! on vectors returns -1 for 'truth', so negate it.
11403	Elt.getInt().negate();
11404	return Elt;
11405	}
11406	assert(Elt.getKind() == APValue::Float &&
11407	"Vector can only be int or float type");
11408	// Float types result in an int of the same size, but -1 for true, or 0 for
11409	// false.
11410	APSInt EltResult{Ctx.getIntWidth(T: ResultTy),
11411	ResultTy->isUnsignedIntegerType()};
11412	if (Elt.getFloat().isZero())
11413	EltResult.setAllBits();
11414	else
11415	EltResult.clearAllBits();
11416
11417	return APValue{EltResult};
11418	}
11419	default:
11420	// FIXME: Implement the rest of the unary operators.
11421	return std::nullopt;
11422	}
11423	}
11424
11425	bool VectorExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
11426	Expr *SubExpr = E->getSubExpr();
11427	const auto *VD = SubExpr->getType()->castAs<VectorType>();
11428	// This result element type differs in the case of negating a floating point
11429	// vector, since the result type is the a vector of the equivilant sized
11430	// integer.
11431	const QualType ResultEltTy = VD->getElementType();
11432	UnaryOperatorKind Op = E->getOpcode();
11433
11434	APValue SubExprValue;
11435	if (!Evaluate(Result&: SubExprValue, Info, E: SubExpr))
11436	return false;
11437
11438	// FIXME: This vector evaluator someday needs to be changed to be LValue
11439	// aware/keep LValue information around, rather than dealing with just vector
11440	// types directly. Until then, we cannot handle cases where the operand to
11441	// these unary operators is an LValue. The only case I've been able to see
11442	// cause this is operator++ assigning to a member expression (only valid in
11443	// altivec compilations) in C mode, so this shouldn't limit us too much.
11444	if (SubExprValue.isLValue())
11445	return false;
11446
11447	assert(SubExprValue.getVectorLength() == VD->getNumElements() &&
11448	"Vector length doesn't match type?");
11449
11450	SmallVector<APValue, 4> ResultElements;
11451	for (unsigned EltNum = 0; EltNum < VD->getNumElements(); ++EltNum) {
11452	std::optional<APValue> Elt = handleVectorUnaryOperator(
11453	Ctx&: Info.Ctx, ResultTy: ResultEltTy, Op, Elt: SubExprValue.getVectorElt(I: EltNum));
11454	if (!Elt)
11455	return false;
11456	ResultElements.push_back(Elt: *Elt);
11457	}
11458	return Success(APValue(ResultElements.data(), ResultElements.size()), E);
11459	}
11460
11461	static bool handleVectorElementCast(EvalInfo &Info, const FPOptions FPO,
11462	const Expr *E, QualType SourceTy,
11463	QualType DestTy, APValue const &Original,
11464	APValue &Result) {
11465	if (SourceTy->isIntegerType()) {
11466	if (DestTy->isRealFloatingType()) {
11467	Result = APValue(APFloat(0.0));
11468	return HandleIntToFloatCast(Info, E, FPO, SrcType: SourceTy, Value: Original.getInt(),
11469	DestType: DestTy, Result&: Result.getFloat());
11470	}
11471	if (DestTy->isIntegerType()) {
11472	Result = APValue(
11473	HandleIntToIntCast(Info, E, DestType: DestTy, SrcType: SourceTy, Value: Original.getInt()));
11474	return true;
11475	}
11476	} else if (SourceTy->isRealFloatingType()) {
11477	if (DestTy->isRealFloatingType()) {
11478	Result = Original;
11479	return HandleFloatToFloatCast(Info, E, SrcType: SourceTy, DestType: DestTy,
11480	Result&: Result.getFloat());
11481	}
11482	if (DestTy->isIntegerType()) {
11483	Result = APValue(APSInt());
11484	return HandleFloatToIntCast(Info, E, SrcType: SourceTy, Value: Original.getFloat(),
11485	DestType: DestTy, Result&: Result.getInt());
11486	}
11487	}
11488
11489	Info.FFDiag(E, diag::err_convertvector_constexpr_unsupported_vector_cast)
11490	<< SourceTy << DestTy;
11491	return false;
11492	}
11493
11494	bool VectorExprEvaluator::VisitCallExpr(const CallExpr *E) {
11495	if (!IsConstantEvaluatedBuiltinCall(E))
11496	return ExprEvaluatorBaseTy::VisitCallExpr(E);
11497
11498	switch (E->getBuiltinCallee()) {
11499	default:
11500	return false;
11501	case Builtin::BI__builtin_elementwise_popcount:
11502	case Builtin::BI__builtin_elementwise_bitreverse: {
11503	APValue Source;
11504	if (!EvaluateAsRValue(Info, E: E->getArg(Arg: 0), Result&: Source))
11505	return false;
11506
11507	QualType DestEltTy = E->getType()->castAs<VectorType>()->getElementType();
11508	unsigned SourceLen = Source.getVectorLength();
11509	SmallVector<APValue, 4> ResultElements;
11510	ResultElements.reserve(N: SourceLen);
11511
11512	for (unsigned EltNum = 0; EltNum < SourceLen; ++EltNum) {
11513	APSInt Elt = Source.getVectorElt(I: EltNum).getInt();
11514	switch (E->getBuiltinCallee()) {
11515	case Builtin::BI__builtin_elementwise_popcount:
11516	ResultElements.push_back(Elt: APValue(
11517	APSInt(APInt(Info.Ctx.getIntWidth(T: DestEltTy), Elt.popcount()),
11518	DestEltTy->isUnsignedIntegerOrEnumerationType())));
11519	break;
11520	case Builtin::BI__builtin_elementwise_bitreverse:
11521	ResultElements.push_back(
11522	Elt: APValue(APSInt(Elt.reverseBits(),
11523	DestEltTy->isUnsignedIntegerOrEnumerationType())));
11524	break;
11525	}
11526	}
11527
11528	return Success(APValue(ResultElements.data(), ResultElements.size()), E);
11529	}
11530	case Builtin::BI__builtin_elementwise_add_sat:
11531	case Builtin::BI__builtin_elementwise_sub_sat: {
11532	APValue SourceLHS, SourceRHS;
11533	if (!EvaluateAsRValue(Info, E: E->getArg(Arg: 0), Result&: SourceLHS) ||
11534	!EvaluateAsRValue(Info, E: E->getArg(Arg: 1), Result&: SourceRHS))
11535	return false;
11536
11537	QualType DestEltTy = E->getType()->castAs<VectorType>()->getElementType();
11538	unsigned SourceLen = SourceLHS.getVectorLength();
11539	SmallVector<APValue, 4> ResultElements;
11540	ResultElements.reserve(N: SourceLen);
11541
11542	for (unsigned EltNum = 0; EltNum < SourceLen; ++EltNum) {
11543	APSInt LHS = SourceLHS.getVectorElt(I: EltNum).getInt();
11544	APSInt RHS = SourceRHS.getVectorElt(I: EltNum).getInt();
11545	switch (E->getBuiltinCallee()) {
11546	case Builtin::BI__builtin_elementwise_add_sat:
11547	ResultElements.push_back(Elt: APValue(
11548	APSInt(LHS.isSigned() ? LHS.sadd_sat(RHS) : RHS.uadd_sat(RHS),
11549	DestEltTy->isUnsignedIntegerOrEnumerationType())));
11550	break;
11551	case Builtin::BI__builtin_elementwise_sub_sat:
11552	ResultElements.push_back(Elt: APValue(
11553	APSInt(LHS.isSigned() ? LHS.ssub_sat(RHS) : RHS.usub_sat(RHS),
11554	DestEltTy->isUnsignedIntegerOrEnumerationType())));
11555	break;
11556	}
11557	}
11558
11559	return Success(APValue(ResultElements.data(), ResultElements.size()), E);
11560	}
11561	}
11562	}
11563
11564	bool VectorExprEvaluator::VisitConvertVectorExpr(const ConvertVectorExpr *E) {
11565	APValue Source;
11566	QualType SourceVecType = E->getSrcExpr()->getType();
11567	if (!EvaluateAsRValue(Info, E: E->getSrcExpr(), Result&: Source))
11568	return false;
11569
11570	QualType DestTy = E->getType()->castAs<VectorType>()->getElementType();
11571	QualType SourceTy = SourceVecType->castAs<VectorType>()->getElementType();
11572
11573	const FPOptions FPO = E->getFPFeaturesInEffect(LO: Info.Ctx.getLangOpts());
11574
11575	auto SourceLen = Source.getVectorLength();
11576	SmallVector<APValue, 4> ResultElements;
11577	ResultElements.reserve(N: SourceLen);
11578	for (unsigned EltNum = 0; EltNum < SourceLen; ++EltNum) {
11579	APValue Elt;
11580	if (!handleVectorElementCast(Info, FPO, E, SourceTy, DestTy,
11581	Source.getVectorElt(I: EltNum), Elt))
11582	return false;
11583	ResultElements.push_back(Elt: std::move(Elt));
11584	}
11585
11586	return Success(APValue(ResultElements.data(), ResultElements.size()), E);
11587	}
11588
11589	static bool handleVectorShuffle(EvalInfo &Info, const ShuffleVectorExpr *E,
11590	QualType ElemType, APValue const &VecVal1,
11591	APValue const &VecVal2, unsigned EltNum,
11592	APValue &Result) {
11593	unsigned const TotalElementsInInputVector1 = VecVal1.getVectorLength();
11594	unsigned const TotalElementsInInputVector2 = VecVal2.getVectorLength();
11595
11596	APSInt IndexVal = E->getShuffleMaskIdx(N: EltNum);
11597	int64_t index = IndexVal.getExtValue();
11598	// The spec says that -1 should be treated as undef for optimizations,
11599	// but in constexpr we'd have to produce an APValue::Indeterminate,
11600	// which is prohibited from being a top-level constant value. Emit a
11601	// diagnostic instead.
11602	if (index == -1) {
11603	Info.FFDiag(
11604	E, diag::err_shufflevector_minus_one_is_undefined_behavior_constexpr)
11605	<< EltNum;
11606	return false;
11607	}
11608
11609	if (index < 0 ||
11610	index >= TotalElementsInInputVector1 + TotalElementsInInputVector2)
11611	llvm_unreachable("Out of bounds shuffle index");
11612
11613	if (index >= TotalElementsInInputVector1)
11614	Result = VecVal2.getVectorElt(I: index - TotalElementsInInputVector1);
11615	else
11616	Result = VecVal1.getVectorElt(I: index);
11617	return true;
11618	}
11619
11620	bool VectorExprEvaluator::VisitShuffleVectorExpr(const ShuffleVectorExpr *E) {
11621	APValue VecVal1;
11622	const Expr *Vec1 = E->getExpr(Index: 0);
11623	if (!EvaluateAsRValue(Info, E: Vec1, Result&: VecVal1))
11624	return false;
11625	APValue VecVal2;
11626	const Expr *Vec2 = E->getExpr(Index: 1);
11627	if (!EvaluateAsRValue(Info, E: Vec2, Result&: VecVal2))
11628	return false;
11629
11630	VectorType const *DestVecTy = E->getType()->castAs<VectorType>();
11631	QualType DestElTy = DestVecTy->getElementType();
11632
11633	auto TotalElementsInOutputVector = DestVecTy->getNumElements();
11634
11635	SmallVector<APValue, 4> ResultElements;
11636	ResultElements.reserve(N: TotalElementsInOutputVector);
11637	for (unsigned EltNum = 0; EltNum < TotalElementsInOutputVector; ++EltNum) {
11638	APValue Elt;
11639	if (!handleVectorShuffle(Info, E, ElemType: DestElTy, VecVal1, VecVal2, EltNum, Result&: Elt))
11640	return false;
11641	ResultElements.push_back(Elt: std::move(Elt));
11642	}
11643
11644	return Success(APValue(ResultElements.data(), ResultElements.size()), E);
11645	}
11646
11647	//===----------------------------------------------------------------------===//
11648	// Array Evaluation
11649	//===----------------------------------------------------------------------===//
11650
11651	namespace {
11652	class ArrayExprEvaluator
11653	: public ExprEvaluatorBase<ArrayExprEvaluator> {
11654	const LValue &This;
11655	APValue &Result;
11656	public:
11657
11658	ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result)
11659	: ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
11660
11661	bool Success(const APValue &V, const Expr *E) {
11662	assert(V.isArray() && "expected array");
11663	Result = V;
11664	return true;
11665	}
11666
11667	bool ZeroInitialization(const Expr *E) {
11668	const ConstantArrayType *CAT =
11669	Info.Ctx.getAsConstantArrayType(T: E->getType());
11670	if (!CAT) {
11671	if (E->getType()->isIncompleteArrayType()) {
11672	// We can be asked to zero-initialize a flexible array member; this
11673	// is represented as an ImplicitValueInitExpr of incomplete array
11674	// type. In this case, the array has zero elements.
11675	Result = APValue(APValue::UninitArray(), 0, 0);
11676	return true;
11677	}
11678	// FIXME: We could handle VLAs here.
11679	return Error(E);
11680	}
11681
11682	Result = APValue(APValue::UninitArray(), 0, CAT->getZExtSize());
11683	if (!Result.hasArrayFiller())
11684	return true;
11685
11686	// Zero-initialize all elements.
11687	LValue Subobject = This;
11688	Subobject.addArray(Info, E, CAT);
11689	ImplicitValueInitExpr VIE(CAT->getElementType());
11690	return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE);
11691	}
11692
11693	bool VisitCallExpr(const CallExpr *E) {
11694	return handleCallExpr(E, Result, ResultSlot: &This);
11695	}
11696	bool VisitInitListExpr(const InitListExpr *E,
11697	QualType AllocType = QualType());
11698	bool VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E);
11699	bool VisitCXXConstructExpr(const CXXConstructExpr *E);
11700	bool VisitCXXConstructExpr(const CXXConstructExpr *E,
11701	const LValue &Subobject,
11702	APValue *Value, QualType Type);
11703	bool VisitStringLiteral(const StringLiteral *E,
11704	QualType AllocType = QualType()) {
11705	expandStringLiteral(Info, S: E, Result, AllocType);
11706	return true;
11707	}
11708	bool VisitCXXParenListInitExpr(const CXXParenListInitExpr *E);
11709	bool VisitCXXParenListOrInitListExpr(const Expr *ExprToVisit,
11710	ArrayRef<Expr *> Args,
11711	const Expr *ArrayFiller,
11712	QualType AllocType = QualType());
11713	};
11714	} // end anonymous namespace
11715
11716	static bool EvaluateArray(const Expr *E, const LValue &This,
11717	APValue &Result, EvalInfo &Info) {
11718	assert(!E->isValueDependent());
11719	assert(E->isPRValue() && E->getType()->isArrayType() &&
11720	"not an array prvalue");
11721	return ArrayExprEvaluator(Info, This, Result).Visit(E);
11722	}
11723
11724	static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This,
11725	APValue &Result, const InitListExpr *ILE,
11726	QualType AllocType) {
11727	assert(!ILE->isValueDependent());
11728	assert(ILE->isPRValue() && ILE->getType()->isArrayType() &&
11729	"not an array prvalue");
11730	return ArrayExprEvaluator(Info, This, Result)
11731	.VisitInitListExpr(E: ILE, AllocType);
11732	}
11733
11734	static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This,
11735	APValue &Result,
11736	const CXXConstructExpr *CCE,
11737	QualType AllocType) {
11738	assert(!CCE->isValueDependent());
11739	assert(CCE->isPRValue() && CCE->getType()->isArrayType() &&
11740	"not an array prvalue");
11741	return ArrayExprEvaluator(Info, This, Result)
11742	.VisitCXXConstructExpr(E: CCE, Subobject: This, Value: &Result, Type: AllocType);
11743	}
11744
11745	// Return true iff the given array filler may depend on the element index.
11746	static bool MaybeElementDependentArrayFiller(const Expr *FillerExpr) {
11747	// For now, just allow non-class value-initialization and initialization
11748	// lists comprised of them.
11749	if (isa<ImplicitValueInitExpr>(Val: FillerExpr))
11750	return false;
11751	if (const InitListExpr *ILE = dyn_cast<InitListExpr>(Val: FillerExpr)) {
11752	for (unsigned I = 0, E = ILE->getNumInits(); I != E; ++I) {
11753	if (MaybeElementDependentArrayFiller(FillerExpr: ILE->getInit(Init: I)))
11754	return true;
11755	}
11756
11757	if (ILE->hasArrayFiller() &&
11758	MaybeElementDependentArrayFiller(FillerExpr: ILE->getArrayFiller()))
11759	return true;
11760
11761	return false;
11762	}
11763	return true;
11764	}
11765
11766	bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E,
11767	QualType AllocType) {
11768	const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
11769	T: AllocType.isNull() ? E->getType() : AllocType);
11770	if (!CAT)
11771	return Error(E);
11772
11773	// C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...]
11774	// an appropriately-typed string literal enclosed in braces.
11775	if (E->isStringLiteralInit()) {
11776	auto *SL = dyn_cast<StringLiteral>(Val: E->getInit(Init: 0)->IgnoreParenImpCasts());
11777	// FIXME: Support ObjCEncodeExpr here once we support it in
11778	// ArrayExprEvaluator generally.
11779	if (!SL)
11780	return Error(E);
11781	return VisitStringLiteral(E: SL, AllocType);
11782	}
11783	// Any other transparent list init will need proper handling of the
11784	// AllocType; we can't just recurse to the inner initializer.
11785	assert(!E->isTransparent() &&
11786	"transparent array list initialization is not string literal init?");
11787
11788	return VisitCXXParenListOrInitListExpr(E, E->inits(), E->getArrayFiller(),
11789	AllocType);
11790	}
11791
11792	bool ArrayExprEvaluator::VisitCXXParenListOrInitListExpr(
11793	const Expr *ExprToVisit, ArrayRef<Expr *> Args, const Expr *ArrayFiller,
11794	QualType AllocType) {
11795	const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
11796	T: AllocType.isNull() ? ExprToVisit->getType() : AllocType);
11797
11798	bool Success = true;
11799
11800	assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) &&
11801	"zero-initialized array shouldn't have any initialized elts");
11802	APValue Filler;
11803	if (Result.isArray() && Result.hasArrayFiller())
11804	Filler = Result.getArrayFiller();
11805
11806	unsigned NumEltsToInit = Args.size();
11807	unsigned NumElts = CAT->getZExtSize();
11808
11809	// If the initializer might depend on the array index, run it for each
11810	// array element.
11811	if (NumEltsToInit != NumElts &&
11812	MaybeElementDependentArrayFiller(FillerExpr: ArrayFiller)) {
11813	NumEltsToInit = NumElts;
11814	} else {
11815	for (auto *Init : Args) {
11816	if (auto *EmbedS = dyn_cast<EmbedExpr>(Val: Init->IgnoreParenImpCasts()))
11817	NumEltsToInit += EmbedS->getDataElementCount() - 1;
11818	}
11819	if (NumEltsToInit > NumElts)
11820	NumEltsToInit = NumElts;
11821	}
11822
11823	LLVM_DEBUG(llvm::dbgs() << "The number of elements to initialize: "
11824	<< NumEltsToInit << ".\n");
11825
11826	Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts);
11827
11828	// If the array was previously zero-initialized, preserve the
11829	// zero-initialized values.
11830	if (Filler.hasValue()) {
11831	for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I)
11832	Result.getArrayInitializedElt(I) = Filler;
11833	if (Result.hasArrayFiller())
11834	Result.getArrayFiller() = Filler;
11835	}
11836
11837	LValue Subobject = This;
11838	Subobject.addArray(Info, E: ExprToVisit, CAT);
11839	auto Eval = [&](const Expr *Init, unsigned ArrayIndex) {
11840	if (Init->isValueDependent())
11841	return EvaluateDependentExpr(E: Init, Info);
11842
11843	if (!EvaluateInPlace(Result&: Result.getArrayInitializedElt(I: ArrayIndex), Info,
11844	This: Subobject, E: Init) ||
11845	!HandleLValueArrayAdjustment(Info, Init, Subobject,
11846	CAT->getElementType(), 1)) {
11847	if (!Info.noteFailure())
11848	return false;
11849	Success = false;
11850	}
11851	return true;
11852	};
11853	unsigned ArrayIndex = 0;
11854	QualType DestTy = CAT->getElementType();
11855	APSInt Value(Info.Ctx.getTypeSize(T: DestTy), DestTy->isUnsignedIntegerType());
11856	for (unsigned Index = 0; Index != NumEltsToInit; ++Index) {
11857	const Expr *Init = Index < Args.size() ? Args[Index] : ArrayFiller;
11858	if (ArrayIndex >= NumEltsToInit)
11859	break;
11860	if (auto *EmbedS = dyn_cast<EmbedExpr>(Val: Init->IgnoreParenImpCasts())) {
11861	StringLiteral *SL = EmbedS->getDataStringLiteral();
11862	for (unsigned I = EmbedS->getStartingElementPos(),
11863	N = EmbedS->getDataElementCount();
11864	I != EmbedS->getStartingElementPos() + N; ++I) {
11865	Value = SL->getCodeUnit(i: I);
11866	if (DestTy->isIntegerType()) {
11867	Result.getArrayInitializedElt(I: ArrayIndex) = APValue(Value);
11868	} else {
11869	assert(DestTy->isFloatingType() && "unexpected type");
11870	const FPOptions FPO =
11871	Init->getFPFeaturesInEffect(LO: Info.Ctx.getLangOpts());
11872	APFloat FValue(0.0);
11873	if (!HandleIntToFloatCast(Info, Init, FPO, EmbedS->getType(), Value,
11874	DestTy, FValue))
11875	return false;
11876	Result.getArrayInitializedElt(I: ArrayIndex) = APValue(FValue);
11877	}
11878	ArrayIndex++;
11879	}
11880	} else {
11881	if (!Eval(Init, ArrayIndex))
11882	return false;
11883	++ArrayIndex;
11884	}
11885	}
11886
11887	if (!Result.hasArrayFiller())
11888	return Success;
11889
11890	// If we get here, we have a trivial filler, which we can just evaluate
11891	// once and splat over the rest of the array elements.
11892	assert(ArrayFiller && "no array filler for incomplete init list");
11893	return EvaluateInPlace(Result&: Result.getArrayFiller(), Info, This: Subobject,
11894	E: ArrayFiller) &&
11895	Success;
11896	}
11897
11898	bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) {
11899	LValue CommonLV;
11900	if (E->getCommonExpr() &&
11901	!Evaluate(Result&: Info.CurrentCall->createTemporary(
11902	Key: E->getCommonExpr(),
11903	T: getStorageType(Info.Ctx, E->getCommonExpr()),
11904	Scope: ScopeKind::FullExpression, LV&: CommonLV),
11905	Info, E: E->getCommonExpr()->getSourceExpr()))
11906	return false;
11907
11908	auto *CAT = cast<ConstantArrayType>(E->getType()->castAsArrayTypeUnsafe());
11909
11910	uint64_t Elements = CAT->getZExtSize();
11911	Result = APValue(APValue::UninitArray(), Elements, Elements);
11912
11913	LValue Subobject = This;
11914	Subobject.addArray(Info, E, CAT: CAT);
11915
11916	bool Success = true;
11917	for (EvalInfo::ArrayInitLoopIndex Index(Info); Index != Elements; ++Index) {
11918	// C++ [class.temporary]/5
11919	// There are four contexts in which temporaries are destroyed at a different
11920	// point than the end of the full-expression. [...] The second context is
11921	// when a copy constructor is called to copy an element of an array while
11922	// the entire array is copied [...]. In either case, if the constructor has
11923	// one or more default arguments, the destruction of every temporary created
11924	// in a default argument is sequenced before the construction of the next
11925	// array element, if any.
11926	FullExpressionRAII Scope(Info);
11927
11928	if (!EvaluateInPlace(Result&: Result.getArrayInitializedElt(I: Index),
11929	Info, This: Subobject, E: E->getSubExpr()) ||
11930	!HandleLValueArrayAdjustment(Info, E, Subobject,
11931	CAT->getElementType(), 1)) {
11932	if (!Info.noteFailure())
11933	return false;
11934	Success = false;
11935	}
11936
11937	// Make sure we run the destructors too.
11938	Scope.destroy();
11939	}
11940
11941	return Success;
11942	}
11943
11944	bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) {
11945	return VisitCXXConstructExpr(E, This, &Result, E->getType());
11946	}
11947
11948	bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
11949	const LValue &Subobject,
11950	APValue *Value,
11951	QualType Type) {
11952	bool HadZeroInit = Value->hasValue();
11953
11954	if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T: Type)) {
11955	unsigned FinalSize = CAT->getZExtSize();
11956
11957	// Preserve the array filler if we had prior zero-initialization.
11958	APValue Filler =
11959	HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller()
11960	: APValue();
11961
11962	*Value = APValue(APValue::UninitArray(), 0, FinalSize);
11963	if (FinalSize == 0)
11964	return true;
11965
11966	bool HasTrivialConstructor = CheckTrivialDefaultConstructor(
11967	Info, E->getExprLoc(), E->getConstructor(),
11968	E->requiresZeroInitialization());
11969	LValue ArrayElt = Subobject;
11970	ArrayElt.addArray(Info, E, CAT);
11971	// We do the whole initialization in two passes, first for just one element,
11972	// then for the whole array. It's possible we may find out we can't do const
11973	// init in the first pass, in which case we avoid allocating a potentially
11974	// large array. We don't do more passes because expanding array requires
11975	// copying the data, which is wasteful.
11976	for (const unsigned N : {1u, FinalSize}) {
11977	unsigned OldElts = Value->getArrayInitializedElts();
11978	if (OldElts == N)
11979	break;
11980
11981	// Expand the array to appropriate size.
11982	APValue NewValue(APValue::UninitArray(), N, FinalSize);
11983	for (unsigned I = 0; I < OldElts; ++I)
11984	NewValue.getArrayInitializedElt(I).swap(
11985	RHS&: Value->getArrayInitializedElt(I));
11986	Value->swap(RHS&: NewValue);
11987
11988	if (HadZeroInit)
11989	for (unsigned I = OldElts; I < N; ++I)
11990	Value->getArrayInitializedElt(I) = Filler;
11991
11992	if (HasTrivialConstructor && N == FinalSize && FinalSize != 1) {
11993	// If we have a trivial constructor, only evaluate it once and copy
11994	// the result into all the array elements.
11995	APValue &FirstResult = Value->getArrayInitializedElt(I: 0);
11996	for (unsigned I = OldElts; I < FinalSize; ++I)
11997	Value->getArrayInitializedElt(I) = FirstResult;
11998	} else {
11999	for (unsigned I = OldElts; I < N; ++I) {
12000	if (!VisitCXXConstructExpr(E, ArrayElt,
12001	&Value->getArrayInitializedElt(I),
12002	CAT->getElementType()) ||
12003	!HandleLValueArrayAdjustment(Info, E, ArrayElt,
12004	CAT->getElementType(), 1))
12005	return false;
12006	// When checking for const initilization any diagnostic is considered
12007	// an error.
12008	if (Info.EvalStatus.Diag && !Info.EvalStatus.Diag->empty() &&
12009	!Info.keepEvaluatingAfterFailure())
12010	return false;
12011	}
12012	}
12013	}
12014
12015	return true;
12016	}
12017
12018	if (!Type->isRecordType())
12019	return Error(E);
12020
12021	return RecordExprEvaluator(Info, Subobject, *Value)
12022	.VisitCXXConstructExpr(E, T: Type);
12023	}
12024
12025	bool ArrayExprEvaluator::VisitCXXParenListInitExpr(
12026	const CXXParenListInitExpr *E) {
12027	assert(E->getType()->isConstantArrayType() &&
12028	"Expression result is not a constant array type");
12029
12030	return VisitCXXParenListOrInitListExpr(E, E->getInitExprs(),
12031	E->getArrayFiller());
12032	}
12033
12034	//===----------------------------------------------------------------------===//
12035	// Integer Evaluation
12036	//
12037	// As a GNU extension, we support casting pointers to sufficiently-wide integer
12038	// types and back in constant folding. Integer values are thus represented
12039	// either as an integer-valued APValue, or as an lvalue-valued APValue.
12040	//===----------------------------------------------------------------------===//
12041
12042	namespace {
12043	class IntExprEvaluator
12044	: public ExprEvaluatorBase<IntExprEvaluator> {
12045	APValue &Result;
12046	public:
12047	IntExprEvaluator(EvalInfo &info, APValue &result)
12048	: ExprEvaluatorBaseTy(info), Result(result) {}
12049
12050	bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) {
12051	assert(E->getType()->isIntegralOrEnumerationType() &&
12052	"Invalid evaluation result.");
12053	assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() &&
12054	"Invalid evaluation result.");
12055	assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
12056	"Invalid evaluation result.");
12057	Result = APValue(SI);
12058	return true;
12059	}
12060	bool Success(const llvm::APSInt &SI, const Expr *E) {
12061	return Success(SI, E, Result);
12062	}
12063
12064	bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) {
12065	assert(E->getType()->isIntegralOrEnumerationType() &&
12066	"Invalid evaluation result.");
12067	assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
12068	"Invalid evaluation result.");
12069	Result = APValue(APSInt(I));
12070	Result.getInt().setIsUnsigned(
12071	E->getType()->isUnsignedIntegerOrEnumerationType());
12072	return true;
12073	}
12074	bool Success(const llvm::APInt &I, const Expr *E) {
12075	return Success(I, E, Result);
12076	}
12077
12078	bool Success(uint64_t Value, const Expr *E, APValue &Result) {
12079	assert(E->getType()->isIntegralOrEnumerationType() &&
12080	"Invalid evaluation result.");
12081	Result = APValue(Info.Ctx.MakeIntValue(Value, Type: E->getType()));
12082	return true;
12083	}
12084	bool Success(uint64_t Value, const Expr *E) {
12085	return Success(Value, E, Result);
12086	}
12087
12088	bool Success(CharUnits Size, const Expr *E) {
12089	return Success(Value: Size.getQuantity(), E);
12090	}
12091
12092	bool Success(const APValue &V, const Expr *E) {
12093	// C++23 [expr.const]p8 If we have a variable that is unknown reference or
12094	// pointer allow further evaluation of the value.
12095	if (V.isLValue() || V.isAddrLabelDiff() || V.isIndeterminate() ||
12096	V.allowConstexprUnknown()) {
12097	Result = V;
12098	return true;
12099	}
12100	return Success(SI: V.getInt(), E);
12101	}
12102
12103	bool ZeroInitialization(const Expr *E) { return Success(Value: 0, E); }
12104
12105	friend std::optional<bool> EvaluateBuiltinIsWithinLifetime(IntExprEvaluator &,
12106	const CallExpr *);
12107
12108	//===--------------------------------------------------------------------===//
12109	// Visitor Methods
12110	//===--------------------------------------------------------------------===//
12111
12112	bool VisitIntegerLiteral(const IntegerLiteral *E) {
12113	return Success(E->getValue(), E);
12114	}
12115	bool VisitCharacterLiteral(const CharacterLiteral *E) {
12116	return Success(E->getValue(), E);
12117	}
12118
12119	bool CheckReferencedDecl(const Expr *E, const Decl *D);
12120	bool VisitDeclRefExpr(const DeclRefExpr *E) {
12121	if (CheckReferencedDecl(E, E->getDecl()))
12122	return true;
12123
12124	return ExprEvaluatorBaseTy::VisitDeclRefExpr(E);
12125	}
12126	bool VisitMemberExpr(const MemberExpr *E) {
12127	if (CheckReferencedDecl(E, E->getMemberDecl())) {
12128	VisitIgnoredBaseExpression(E: E->getBase());
12129	return true;
12130	}
12131
12132	return ExprEvaluatorBaseTy::VisitMemberExpr(E);
12133	}
12134
12135	bool VisitCallExpr(const CallExpr *E);
12136	bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
12137	bool VisitBinaryOperator(const BinaryOperator *E);
12138	bool VisitOffsetOfExpr(const OffsetOfExpr *E);
12139	bool VisitUnaryOperator(const UnaryOperator *E);
12140
12141	bool VisitCastExpr(const CastExpr* E);
12142	bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E);
12143
12144	bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
12145	return Success(E->getValue(), E);
12146	}
12147
12148	bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) {
12149	return Success(E->getValue(), E);
12150	}
12151
12152	bool VisitArrayInitIndexExpr(const ArrayInitIndexExpr *E) {
12153	if (Info.ArrayInitIndex == uint64_t(-1)) {
12154	// We were asked to evaluate this subexpression independent of the
12155	// enclosing ArrayInitLoopExpr. We can't do that.
12156	Info.FFDiag(E);
12157	return false;
12158	}
12159	return Success(Info.ArrayInitIndex, E);
12160	}
12161
12162	// Note, GNU defines __null as an integer, not a pointer.
12163	bool VisitGNUNullExpr(const GNUNullExpr *E) {
12164	return ZeroInitialization(E);
12165	}
12166
12167	bool VisitTypeTraitExpr(const TypeTraitExpr *E) {
12168	if (E->isStoredAsBoolean())
12169	return Success(E->getBoolValue(), E);
12170	if (E->getAPValue().isAbsent())
12171	return false;
12172	assert(E->getAPValue().isInt() && "APValue type not supported");
12173	return Success(E->getAPValue().getInt(), E);
12174	}
12175
12176	bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) {
12177	return Success(E->getValue(), E);
12178	}
12179
12180	bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) {
12181	return Success(E->getValue(), E);
12182	}
12183
12184	bool VisitOpenACCAsteriskSizeExpr(const OpenACCAsteriskSizeExpr *E) {
12185	// This should not be evaluated during constant expr evaluation, as it
12186	// should always be in an unevaluated context (the args list of a 'gang' or
12187	// 'tile' clause).
12188	return Error(E);
12189	}
12190
12191	bool VisitUnaryReal(const UnaryOperator *E);
12192	bool VisitUnaryImag(const UnaryOperator *E);
12193
12194	bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E);
12195	bool VisitSizeOfPackExpr(const SizeOfPackExpr *E);
12196	bool VisitSourceLocExpr(const SourceLocExpr *E);
12197	bool VisitConceptSpecializationExpr(const ConceptSpecializationExpr *E);
12198	bool VisitRequiresExpr(const RequiresExpr *E);
12199	// FIXME: Missing: array subscript of vector, member of vector
12200	};
12201
12202	class FixedPointExprEvaluator
12203	: public ExprEvaluatorBase<FixedPointExprEvaluator> {
12204	APValue &Result;
12205
12206	public:
12207	FixedPointExprEvaluator(EvalInfo &info, APValue &result)
12208	: ExprEvaluatorBaseTy(info), Result(result) {}
12209
12210	bool Success(const llvm::APInt &I, const Expr *E) {
12211	return Success(
12212	V: APFixedPoint(I, Info.Ctx.getFixedPointSemantics(Ty: E->getType())), E);
12213	}
12214
12215	bool Success(uint64_t Value, const Expr *E) {
12216	return Success(
12217	V: APFixedPoint(Value, Info.Ctx.getFixedPointSemantics(Ty: E->getType())), E);
12218	}
12219
12220	bool Success(const APValue &V, const Expr *E) {
12221	return Success(V: V.getFixedPoint(), E);
12222	}
12223
12224	bool Success(const APFixedPoint &V, const Expr *E) {
12225	assert(E->getType()->isFixedPointType() && "Invalid evaluation result.");
12226	assert(V.getWidth() == Info.Ctx.getIntWidth(E->getType()) &&
12227	"Invalid evaluation result.");
12228	Result = APValue(V);
12229	return true;
12230	}
12231
12232	bool ZeroInitialization(const Expr *E) {
12233	return Success(Value: 0, E);
12234	}
12235
12236	//===--------------------------------------------------------------------===//
12237	// Visitor Methods
12238	//===--------------------------------------------------------------------===//
12239
12240	bool VisitFixedPointLiteral(const FixedPointLiteral *E) {
12241	return Success(E->getValue(), E);
12242	}
12243
12244	bool VisitCastExpr(const CastExpr *E);
12245	bool VisitUnaryOperator(const UnaryOperator *E);
12246	bool VisitBinaryOperator(const BinaryOperator *E);
12247	};
12248	} // end anonymous namespace
12249
12250	/// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and
12251	/// produce either the integer value or a pointer.
12252	///
12253	/// GCC has a heinous extension which folds casts between pointer types and
12254	/// pointer-sized integral types. We support this by allowing the evaluation of
12255	/// an integer rvalue to produce a pointer (represented as an lvalue) instead.
12256	/// Some simple arithmetic on such values is supported (they are treated much
12257	/// like char*).
12258	static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
12259	EvalInfo &Info) {
12260	assert(!E->isValueDependent());
12261	assert(E->isPRValue() && E->getType()->isIntegralOrEnumerationType());
12262	return IntExprEvaluator(Info, Result).Visit(E);
12263	}
12264
12265	static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) {
12266	assert(!E->isValueDependent());
12267	APValue Val;
12268	if (!EvaluateIntegerOrLValue(E, Result&: Val, Info))
12269	return false;
12270	if (!Val.isInt()) {
12271	// FIXME: It would be better to produce the diagnostic for casting
12272	// a pointer to an integer.
12273	Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
12274	return false;
12275	}
12276	Result = Val.getInt();
12277	return true;
12278	}
12279
12280	bool IntExprEvaluator::VisitSourceLocExpr(const SourceLocExpr *E) {
12281	APValue Evaluated = E->EvaluateInContext(
12282	Ctx: Info.Ctx, DefaultExpr: Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr());
12283	return Success(Evaluated, E);
12284	}
12285
12286	static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
12287	EvalInfo &Info) {
12288	assert(!E->isValueDependent());
12289	if (E->getType()->isFixedPointType()) {
12290	APValue Val;
12291	if (!FixedPointExprEvaluator(Info, Val).Visit(E))
12292	return false;
12293	if (!Val.isFixedPoint())
12294	return false;
12295
12296	Result = Val.getFixedPoint();
12297	return true;
12298	}
12299	return false;
12300	}
12301
12302	static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
12303	EvalInfo &Info) {
12304	assert(!E->isValueDependent());
12305	if (E->getType()->isIntegerType()) {
12306	auto FXSema = Info.Ctx.getFixedPointSemantics(Ty: E->getType());
12307	APSInt Val;
12308	if (!EvaluateInteger(E, Result&: Val, Info))
12309	return false;
12310	Result = APFixedPoint(Val, FXSema);
12311	return true;
12312	} else if (E->getType()->isFixedPointType()) {
12313	return EvaluateFixedPoint(E, Result, Info);
12314	}
12315	return false;
12316	}
12317
12318	/// Check whether the given declaration can be directly converted to an integral
12319	/// rvalue. If not, no diagnostic is produced; there are other things we can
12320	/// try.
12321	bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) {
12322	// Enums are integer constant exprs.
12323	if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(Val: D)) {
12324	// Check for signedness/width mismatches between E type and ECD value.
12325	bool SameSign = (ECD->getInitVal().isSigned()
12326	== E->getType()->isSignedIntegerOrEnumerationType());
12327	bool SameWidth = (ECD->getInitVal().getBitWidth()
12328	== Info.Ctx.getIntWidth(T: E->getType()));
12329	if (SameSign && SameWidth)
12330	return Success(SI: ECD->getInitVal(), E);
12331	else {
12332	// Get rid of mismatch (otherwise Success assertions will fail)
12333	// by computing a new value matching the type of E.
12334	llvm::APSInt Val = ECD->getInitVal();
12335	if (!SameSign)
12336	Val.setIsSigned(!ECD->getInitVal().isSigned());
12337	if (!SameWidth)
12338	Val = Val.extOrTrunc(width: Info.Ctx.getIntWidth(T: E->getType()));
12339	return Success(SI: Val, E);
12340	}
12341	}
12342	return false;
12343	}
12344
12345	/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
12346	/// as GCC.
12347	GCCTypeClass EvaluateBuiltinClassifyType(QualType T,
12348	const LangOptions &LangOpts) {
12349	assert(!T->isDependentType() && "unexpected dependent type");
12350
12351	QualType CanTy = T.getCanonicalType();
12352
12353	switch (CanTy->getTypeClass()) {
12354	#define TYPE(ID, BASE)
12355	#define DEPENDENT_TYPE(ID, BASE) case Type::ID:
12356	#define NON_CANONICAL_TYPE(ID, BASE) case Type::ID:
12357	#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(ID, BASE) case Type::ID:
12358	#include "clang/AST/TypeNodes.inc"
12359	case Type::Auto:
12360	case Type::DeducedTemplateSpecialization:
12361	llvm_unreachable("unexpected non-canonical or dependent type");
12362
12363	case Type::Builtin:
12364	switch (cast<BuiltinType>(CanTy)->getKind()) {
12365	#define BUILTIN_TYPE(ID, SINGLETON_ID)
12366	#define SIGNED_TYPE(ID, SINGLETON_ID) \
12367	case BuiltinType::ID: return GCCTypeClass::Integer;
12368	#define FLOATING_TYPE(ID, SINGLETON_ID) \
12369	case BuiltinType::ID: return GCCTypeClass::RealFloat;
12370	#define PLACEHOLDER_TYPE(ID, SINGLETON_ID) \
12371	case BuiltinType::ID: break;
12372	#include "clang/AST/BuiltinTypes.def"
12373	case BuiltinType::Void:
12374	return GCCTypeClass::Void;
12375
12376	case BuiltinType::Bool:
12377	return GCCTypeClass::Bool;
12378
12379	case BuiltinType::Char_U:
12380	case BuiltinType::UChar:
12381	case BuiltinType::WChar_U:
12382	case BuiltinType::Char8:
12383	case BuiltinType::Char16:
12384	case BuiltinType::Char32:
12385	case BuiltinType::UShort:
12386	case BuiltinType::UInt:
12387	case BuiltinType::ULong:
12388	case BuiltinType::ULongLong:
12389	case BuiltinType::UInt128:
12390	return GCCTypeClass::Integer;
12391
12392	case BuiltinType::UShortAccum:
12393	case BuiltinType::UAccum:
12394	case BuiltinType::ULongAccum:
12395	case BuiltinType::UShortFract:
12396	case BuiltinType::UFract:
12397	case BuiltinType::ULongFract:
12398	case BuiltinType::SatUShortAccum:
12399	case BuiltinType::SatUAccum:
12400	case BuiltinType::SatULongAccum:
12401	case BuiltinType::SatUShortFract:
12402	case BuiltinType::SatUFract:
12403	case BuiltinType::SatULongFract:
12404	return GCCTypeClass::None;
12405
12406	case BuiltinType::NullPtr:
12407
12408	case BuiltinType::ObjCId:
12409	case BuiltinType::ObjCClass:
12410	case BuiltinType::ObjCSel:
12411	#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
12412	case BuiltinType::Id:
12413	#include "clang/Basic/OpenCLImageTypes.def"
12414	#define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
12415	case BuiltinType::Id:
12416	#include "clang/Basic/OpenCLExtensionTypes.def"
12417	case BuiltinType::OCLSampler:
12418	case BuiltinType::OCLEvent:
12419	case BuiltinType::OCLClkEvent:
12420	case BuiltinType::OCLQueue:
12421	case BuiltinType::OCLReserveID:
12422	#define SVE_TYPE(Name, Id, SingletonId) \
12423	case BuiltinType::Id:
12424	#include "clang/Basic/AArch64ACLETypes.def"
12425	#define PPC_VECTOR_TYPE(Name, Id, Size) \
12426	case BuiltinType::Id:
12427	#include "clang/Basic/PPCTypes.def"
12428	#define RVV_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
12429	#include "clang/Basic/RISCVVTypes.def"
12430	#define WASM_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
12431	#include "clang/Basic/WebAssemblyReferenceTypes.def"
12432	#define AMDGPU_TYPE(Name, Id, SingletonId, Width, Align) case BuiltinType::Id:
12433	#include "clang/Basic/AMDGPUTypes.def"
12434	#define HLSL_INTANGIBLE_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
12435	#include "clang/Basic/HLSLIntangibleTypes.def"
12436	return GCCTypeClass::None;
12437
12438	case BuiltinType::Dependent:
12439	llvm_unreachable("unexpected dependent type");
12440	};
12441	llvm_unreachable("unexpected placeholder type");
12442
12443	case Type::Enum:
12444	return LangOpts.CPlusPlus ? GCCTypeClass::Enum : GCCTypeClass::Integer;
12445
12446	case Type::Pointer:
12447	case Type::ConstantArray:
12448	case Type::VariableArray:
12449	case Type::IncompleteArray:
12450	case Type::FunctionNoProto:
12451	case Type::FunctionProto:
12452	case Type::ArrayParameter:
12453	return GCCTypeClass::Pointer;
12454
12455	case Type::MemberPointer:
12456	return CanTy->isMemberDataPointerType()
12457	? GCCTypeClass::PointerToDataMember
12458	: GCCTypeClass::PointerToMemberFunction;
12459
12460	case Type::Complex:
12461	return GCCTypeClass::Complex;
12462
12463	case Type::Record:
12464	return CanTy->isUnionType() ? GCCTypeClass::Union
12465	: GCCTypeClass::ClassOrStruct;
12466
12467	case Type::Atomic:
12468	// GCC classifies _Atomic T the same as T.
12469	return EvaluateBuiltinClassifyType(
12470	CanTy->castAs<AtomicType>()->getValueType(), LangOpts);
12471
12472	case Type::Vector:
12473	case Type::ExtVector:
12474	return GCCTypeClass::Vector;
12475
12476	case Type::BlockPointer:
12477	case Type::ConstantMatrix:
12478	case Type::ObjCObject:
12479	case Type::ObjCInterface:
12480	case Type::ObjCObjectPointer:
12481	case Type::Pipe:
12482	case Type::HLSLAttributedResource:
12483	case Type::HLSLInlineSpirv:
12484	// Classify all other types that don't fit into the regular
12485	// classification the same way.
12486	return GCCTypeClass::None;
12487
12488	case Type::BitInt:
12489	return GCCTypeClass::BitInt;
12490
12491	case Type::LValueReference:
12492	case Type::RValueReference:
12493	llvm_unreachable("invalid type for expression");
12494	}
12495
12496	llvm_unreachable("unexpected type class");
12497	}
12498
12499	/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
12500	/// as GCC.
12501	static GCCTypeClass
12502	EvaluateBuiltinClassifyType(const CallExpr *E, const LangOptions &LangOpts) {
12503	// If no argument was supplied, default to None. This isn't
12504	// ideal, however it is what gcc does.
12505	if (E->getNumArgs() == 0)
12506	return GCCTypeClass::None;
12507
12508	// FIXME: Bizarrely, GCC treats a call with more than one argument as not
12509	// being an ICE, but still folds it to a constant using the type of the first
12510	// argument.
12511	return EvaluateBuiltinClassifyType(T: E->getArg(Arg: 0)->getType(), LangOpts);
12512	}
12513
12514	/// EvaluateBuiltinConstantPForLValue - Determine the result of
12515	/// __builtin_constant_p when applied to the given pointer.
12516	///
12517	/// A pointer is only "constant" if it is null (or a pointer cast to integer)
12518	/// or it points to the first character of a string literal.
12519	static bool EvaluateBuiltinConstantPForLValue(const APValue &LV) {
12520	APValue::LValueBase Base = LV.getLValueBase();
12521	if (Base.isNull()) {
12522	// A null base is acceptable.
12523	return true;
12524	} else if (const Expr *E = Base.dyn_cast<const Expr *>()) {
12525	if (!isa<StringLiteral>(Val: E))
12526	return false;
12527	return LV.getLValueOffset().isZero();
12528	} else if (Base.is<TypeInfoLValue>()) {
12529	// Surprisingly, GCC considers __builtin_constant_p(&typeid(int)) to
12530	// evaluate to true.
12531	return true;
12532	} else {
12533	// Any other base is not constant enough for GCC.
12534	return false;
12535	}
12536	}
12537
12538	/// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to
12539	/// GCC as we can manage.
12540	static bool EvaluateBuiltinConstantP(EvalInfo &Info, const Expr *Arg) {
12541	// This evaluation is not permitted to have side-effects, so evaluate it in
12542	// a speculative evaluation context.
12543	SpeculativeEvaluationRAII SpeculativeEval(Info);
12544
12545	// Constant-folding is always enabled for the operand of __builtin_constant_p
12546	// (even when the enclosing evaluation context otherwise requires a strict
12547	// language-specific constant expression).
12548	FoldConstant Fold(Info, true);
12549
12550	QualType ArgType = Arg->getType();
12551
12552	// __builtin_constant_p always has one operand. The rules which gcc follows
12553	// are not precisely documented, but are as follows:
12554	//
12555	// - If the operand is of integral, floating, complex or enumeration type,
12556	// and can be folded to a known value of that type, it returns 1.
12557	// - If the operand can be folded to a pointer to the first character
12558	// of a string literal (or such a pointer cast to an integral type)
12559	// or to a null pointer or an integer cast to a pointer, it returns 1.
12560	//
12561	// Otherwise, it returns 0.
12562	//
12563	// FIXME: GCC also intends to return 1 for literals of aggregate types, but
12564	// its support for this did not work prior to GCC 9 and is not yet well
12565	// understood.
12566	if (ArgType->isIntegralOrEnumerationType() || ArgType->isFloatingType() ||
12567	ArgType->isAnyComplexType() || ArgType->isPointerType() ||
12568	ArgType->isNullPtrType()) {
12569	APValue V;
12570	if (!::EvaluateAsRValue(Info, E: Arg, Result&: V) || Info.EvalStatus.HasSideEffects) {
12571	Fold.keepDiagnostics();
12572	return false;
12573	}
12574
12575	// For a pointer (possibly cast to integer), there are special rules.
12576	if (V.getKind() == APValue::LValue)
12577	return EvaluateBuiltinConstantPForLValue(LV: V);
12578
12579	// Otherwise, any constant value is good enough.
12580	return V.hasValue();
12581	}
12582
12583	// Anything else isn't considered to be sufficiently constant.
12584	return false;
12585	}
12586
12587	/// Retrieves the "underlying object type" of the given expression,
12588	/// as used by __builtin_object_size.
12589	static QualType getObjectType(APValue::LValueBase B) {
12590	if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
12591	if (const VarDecl *VD = dyn_cast<VarDecl>(Val: D))
12592	return VD->getType();
12593	} else if (const Expr *E = B.dyn_cast<const Expr*>()) {
12594	if (isa<CompoundLiteralExpr>(Val: E))
12595	return E->getType();
12596	} else if (B.is<TypeInfoLValue>()) {
12597	return B.getTypeInfoType();
12598	} else if (B.is<DynamicAllocLValue>()) {
12599	return B.getDynamicAllocType();
12600	}
12601
12602	return QualType();
12603	}
12604
12605	/// A more selective version of E->IgnoreParenCasts for
12606	/// tryEvaluateBuiltinObjectSize. This ignores some casts/parens that serve only
12607	/// to change the type of E.
12608	/// Ex. For E = `(short*)((char*)(&foo))`, returns `&foo`
12609	///
12610	/// Always returns an RValue with a pointer representation.
12611	static const Expr *ignorePointerCastsAndParens(const Expr *E) {
12612	assert(E->isPRValue() && E->getType()->hasPointerRepresentation());
12613
12614	const Expr *NoParens = E->IgnoreParens();
12615	const auto *Cast = dyn_cast<CastExpr>(Val: NoParens);
12616	if (Cast == nullptr)
12617	return NoParens;
12618
12619	// We only conservatively allow a few kinds of casts, because this code is
12620	// inherently a simple solution that seeks to support the common case.
12621	auto CastKind = Cast->getCastKind();
12622	if (CastKind != CK_NoOp && CastKind != CK_BitCast &&
12623	CastKind != CK_AddressSpaceConversion)
12624	return NoParens;
12625
12626	const auto *SubExpr = Cast->getSubExpr();
12627	if (!SubExpr->getType()->hasPointerRepresentation() || !SubExpr->isPRValue())
12628	return NoParens;
12629	return ignorePointerCastsAndParens(E: SubExpr);
12630	}
12631
12632	/// Checks to see if the given LValue's Designator is at the end of the LValue's
12633	/// record layout. e.g.
12634	/// struct { struct { int a, b; } fst, snd; } obj;
12635	/// obj.fst // no
12636	/// obj.snd // yes
12637	/// obj.fst.a // no
12638	/// obj.fst.b // no
12639	/// obj.snd.a // no
12640	/// obj.snd.b // yes
12641	///
12642	/// Please note: this function is specialized for how __builtin_object_size
12643	/// views "objects".
12644	///
12645	/// If this encounters an invalid RecordDecl or otherwise cannot determine the
12646	/// correct result, it will always return true.
12647	static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
12648	assert(!LVal.Designator.Invalid);
12649
12650	auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD) {
12651	const RecordDecl *Parent = FD->getParent();
12652	if (Parent->isInvalidDecl() || Parent->isUnion())
12653	return true;
12654	const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(D: Parent);
12655	return FD->getFieldIndex() + 1 == Layout.getFieldCount();
12656	};
12657
12658	auto &Base = LVal.getLValueBase();
12659	if (auto *ME = dyn_cast_or_null<MemberExpr>(Val: Base.dyn_cast<const Expr *>())) {
12660	if (auto *FD = dyn_cast<FieldDecl>(Val: ME->getMemberDecl())) {
12661	if (!IsLastOrInvalidFieldDecl(FD))
12662	return false;
12663	} else if (auto *IFD = dyn_cast<IndirectFieldDecl>(Val: ME->getMemberDecl())) {
12664	for (auto *FD : IFD->chain()) {
12665	if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(Val: FD)))
12666	return false;
12667	}
12668	}
12669	}
12670
12671	unsigned I = 0;
12672	QualType BaseType = getType(B: Base);
12673	if (LVal.Designator.FirstEntryIsAnUnsizedArray) {
12674	// If we don't know the array bound, conservatively assume we're looking at
12675	// the final array element.
12676	++I;
12677	if (BaseType->isIncompleteArrayType())
12678	BaseType = Ctx.getAsArrayType(T: BaseType)->getElementType();
12679	else
12680	BaseType = BaseType->castAs<PointerType>()->getPointeeType();
12681	}
12682
12683	for (unsigned E = LVal.Designator.Entries.size(); I != E; ++I) {
12684	const auto &Entry = LVal.Designator.Entries[I];
12685	if (BaseType->isArrayType()) {
12686	// Because __builtin_object_size treats arrays as objects, we can ignore
12687	// the index iff this is the last array in the Designator.
12688	if (I + 1 == E)
12689	return true;
12690	const auto *CAT = cast<ConstantArrayType>(Val: Ctx.getAsArrayType(T: BaseType));
12691	uint64_t Index = Entry.getAsArrayIndex();
12692	if (Index + 1 != CAT->getZExtSize())
12693	return false;
12694	BaseType = CAT->getElementType();
12695	} else if (BaseType->isAnyComplexType()) {
12696	const auto *CT = BaseType->castAs<ComplexType>();
12697	uint64_t Index = Entry.getAsArrayIndex();
12698	if (Index != 1)
12699	return false;
12700	BaseType = CT->getElementType();
12701	} else if (auto *FD = getAsField(Entry)) {
12702	if (!IsLastOrInvalidFieldDecl(FD))
12703	return false;
12704	BaseType = FD->getType();
12705	} else {
12706	assert(getAsBaseClass(Entry) && "Expecting cast to a base class");
12707	return false;
12708	}
12709	}
12710	return true;
12711	}
12712
12713	/// Tests to see if the LValue has a user-specified designator (that isn't
12714	/// necessarily valid). Note that this always returns 'true' if the LValue has
12715	/// an unsized array as its first designator entry, because there's currently no
12716	/// way to tell if the user typed *foo or foo[0].
12717	static bool refersToCompleteObject(const LValue &LVal) {
12718	if (LVal.Designator.Invalid)
12719	return false;
12720
12721	if (!LVal.Designator.Entries.empty())
12722	return LVal.Designator.isMostDerivedAnUnsizedArray();
12723
12724	if (!LVal.InvalidBase)
12725	return true;
12726
12727	// If `E` is a MemberExpr, then the first part of the designator is hiding in
12728	// the LValueBase.
12729	const auto *E = LVal.Base.dyn_cast<const Expr *>();
12730	return !E || !isa<MemberExpr>(Val: E);
12731	}
12732
12733	/// Attempts to detect a user writing into a piece of memory that's impossible
12734	/// to figure out the size of by just using types.
12735	static bool isUserWritingOffTheEnd(const ASTContext &Ctx, const LValue &LVal) {
12736	const SubobjectDesignator &Designator = LVal.Designator;
12737	// Notes:
12738	// - Users can only write off of the end when we have an invalid base. Invalid
12739	// bases imply we don't know where the memory came from.
12740	// - We used to be a bit more aggressive here; we'd only be conservative if
12741	// the array at the end was flexible, or if it had 0 or 1 elements. This
12742	// broke some common standard library extensions (PR30346), but was
12743	// otherwise seemingly fine. It may be useful to reintroduce this behavior
12744	// with some sort of list. OTOH, it seems that GCC is always
12745	// conservative with the last element in structs (if it's an array), so our
12746	// current behavior is more compatible than an explicit list approach would
12747	// be.
12748	auto isFlexibleArrayMember = [&] {
12749	using FAMKind = LangOptions::StrictFlexArraysLevelKind;
12750	FAMKind StrictFlexArraysLevel =
12751	Ctx.getLangOpts().getStrictFlexArraysLevel();
12752
12753	if (Designator.isMostDerivedAnUnsizedArray())
12754	return true;
12755
12756	if (StrictFlexArraysLevel == FAMKind::Default)
12757	return true;
12758
12759	if (Designator.getMostDerivedArraySize() == 0 &&
12760	StrictFlexArraysLevel != FAMKind::IncompleteOnly)
12761	return true;
12762
12763	if (Designator.getMostDerivedArraySize() == 1 &&
12764	StrictFlexArraysLevel == FAMKind::OneZeroOrIncomplete)
12765	return true;
12766
12767	return false;
12768	};
12769
12770	return LVal.InvalidBase &&
12771	Designator.Entries.size() == Designator.MostDerivedPathLength &&
12772	Designator.MostDerivedIsArrayElement && isFlexibleArrayMember() &&
12773	isDesignatorAtObjectEnd(Ctx, LVal);
12774	}
12775
12776	/// Converts the given APInt to CharUnits, assuming the APInt is unsigned.
12777	/// Fails if the conversion would cause loss of precision.
12778	static bool convertUnsignedAPIntToCharUnits(const llvm::APInt &Int,
12779	CharUnits &Result) {
12780	auto CharUnitsMax = std::numeric_limits<CharUnits::QuantityType>::max();
12781	if (Int.ugt(RHS: CharUnitsMax))
12782	return false;
12783	Result = CharUnits::fromQuantity(Quantity: Int.getZExtValue());
12784	return true;
12785	}
12786
12787	/// If we're evaluating the object size of an instance of a struct that
12788	/// contains a flexible array member, add the size of the initializer.
12789	static void addFlexibleArrayMemberInitSize(EvalInfo &Info, const QualType &T,
12790	const LValue &LV, CharUnits &Size) {
12791	if (!T.isNull() && T->isStructureType() &&
12792	T->getAsStructureType()->getDecl()->hasFlexibleArrayMember())
12793	if (const auto *V = LV.getLValueBase().dyn_cast<const ValueDecl *>())
12794	if (const auto *VD = dyn_cast<VarDecl>(Val: V))
12795	if (VD->hasInit())
12796	Size += VD->getFlexibleArrayInitChars(Ctx: Info.Ctx);
12797	}
12798
12799	/// Helper for tryEvaluateBuiltinObjectSize -- Given an LValue, this will
12800	/// determine how many bytes exist from the beginning of the object to either
12801	/// the end of the current subobject, or the end of the object itself, depending
12802	/// on what the LValue looks like + the value of Type.
12803	///
12804	/// If this returns false, the value of Result is undefined.
12805	static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc,
12806	unsigned Type, const LValue &LVal,
12807	CharUnits &EndOffset) {
12808	bool DetermineForCompleteObject = refersToCompleteObject(LVal);
12809
12810	auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) {
12811	if (Ty.isNull())
12812	return false;
12813
12814	Ty = Ty.getNonReferenceType();
12815
12816	if (Ty->isIncompleteType() || Ty->isFunctionType())
12817	return false;
12818
12819	return HandleSizeof(Info, Loc: ExprLoc, Type: Ty, Size&: Result);
12820	};
12821
12822	// We want to evaluate the size of the entire object. This is a valid fallback
12823	// for when Type=1 and the designator is invalid, because we're asked for an
12824	// upper-bound.
12825	if (!(Type & 1) || LVal.Designator.Invalid || DetermineForCompleteObject) {
12826	// Type=3 wants a lower bound, so we can't fall back to this.
12827	if (Type == 3 && !DetermineForCompleteObject)
12828	return false;
12829
12830	llvm::APInt APEndOffset;
12831	if (isBaseAnAllocSizeCall(Base: LVal.getLValueBase()) &&
12832	getBytesReturnedByAllocSizeCall(Ctx: Info.Ctx, LVal, Result&: APEndOffset))
12833	return convertUnsignedAPIntToCharUnits(Int: APEndOffset, Result&: EndOffset);
12834
12835	if (LVal.InvalidBase)
12836	return false;
12837
12838	QualType BaseTy = getObjectType(B: LVal.getLValueBase());
12839	const bool Ret = CheckedHandleSizeof(BaseTy, EndOffset);
12840	addFlexibleArrayMemberInitSize(Info, T: BaseTy, LV: LVal, Size&: EndOffset);
12841	return Ret;
12842	}
12843
12844	// We want to evaluate the size of a subobject.
12845	const SubobjectDesignator &Designator = LVal.Designator;
12846
12847	// The following is a moderately common idiom in C:
12848	//
12849	// struct Foo { int a; char c[1]; };
12850	// struct Foo *F = (struct Foo *)malloc(sizeof(struct Foo) + strlen(Bar));
12851	// strcpy(&F->c[0], Bar);
12852	//
12853	// In order to not break too much legacy code, we need to support it.
12854	if (isUserWritingOffTheEnd(Ctx: Info.Ctx, LVal)) {
12855	// If we can resolve this to an alloc_size call, we can hand that back,
12856	// because we know for certain how many bytes there are to write to.
12857	llvm::APInt APEndOffset;
12858	if (isBaseAnAllocSizeCall(Base: LVal.getLValueBase()) &&
12859	getBytesReturnedByAllocSizeCall(Ctx: Info.Ctx, LVal, Result&: APEndOffset))
12860	return convertUnsignedAPIntToCharUnits(Int: APEndOffset, Result&: EndOffset);
12861
12862	// If we cannot determine the size of the initial allocation, then we can't
12863	// given an accurate upper-bound. However, we are still able to give
12864	// conservative lower-bounds for Type=3.
12865	if (Type == 1)
12866	return false;
12867	}
12868
12869	CharUnits BytesPerElem;
12870	if (!CheckedHandleSizeof(Designator.MostDerivedType, BytesPerElem))
12871	return false;
12872
12873	// According to the GCC documentation, we want the size of the subobject
12874	// denoted by the pointer. But that's not quite right -- what we actually
12875	// want is the size of the immediately-enclosing array, if there is one.
12876	int64_t ElemsRemaining;
12877	if (Designator.MostDerivedIsArrayElement &&
12878	Designator.Entries.size() == Designator.MostDerivedPathLength) {
12879	uint64_t ArraySize = Designator.getMostDerivedArraySize();
12880	uint64_t ArrayIndex = Designator.Entries.back().getAsArrayIndex();
12881	ElemsRemaining = ArraySize <= ArrayIndex ? 0 : ArraySize - ArrayIndex;
12882	} else {
12883	ElemsRemaining = Designator.isOnePastTheEnd() ? 0 : 1;
12884	}
12885
12886	EndOffset = LVal.getLValueOffset() + BytesPerElem * ElemsRemaining;
12887	return true;
12888	}
12889
12890	/// Tries to evaluate the __builtin_object_size for @p E. If successful,
12891	/// returns true and stores the result in @p Size.
12892	///
12893	/// If @p WasError is non-null, this will report whether the failure to evaluate
12894	/// is to be treated as an Error in IntExprEvaluator.
12895	static bool tryEvaluateBuiltinObjectSize(const Expr *E, unsigned Type,
12896	EvalInfo &Info, uint64_t &Size) {
12897	// Determine the denoted object.
12898	LValue LVal;
12899	{
12900	// The operand of __builtin_object_size is never evaluated for side-effects.
12901	// If there are any, but we can determine the pointed-to object anyway, then
12902	// ignore the side-effects.
12903	SpeculativeEvaluationRAII SpeculativeEval(Info);
12904	IgnoreSideEffectsRAII Fold(Info);
12905
12906	if (E->isGLValue()) {
12907	// It's possible for us to be given GLValues if we're called via
12908	// Expr::tryEvaluateObjectSize.
12909	APValue RVal;
12910	if (!EvaluateAsRValue(Info, E, Result&: RVal))
12911	return false;
12912	LVal.setFrom(Ctx&: Info.Ctx, V: RVal);
12913	} else if (!EvaluatePointer(E: ignorePointerCastsAndParens(E), Result&: LVal, Info,
12914	/*InvalidBaseOK=*/true))
12915	return false;
12916	}
12917
12918	// If we point to before the start of the object, there are no accessible
12919	// bytes.
12920	if (LVal.getLValueOffset().isNegative()) {
12921	Size = 0;
12922	return true;
12923	}
12924
12925	CharUnits EndOffset;
12926	if (!determineEndOffset(Info, ExprLoc: E->getExprLoc(), Type, LVal, EndOffset))
12927	return false;
12928
12929	// If we've fallen outside of the end offset, just pretend there's nothing to
12930	// write to/read from.
12931	if (EndOffset <= LVal.getLValueOffset())
12932	Size = 0;
12933	else
12934	Size = (EndOffset - LVal.getLValueOffset()).getQuantity();
12935	return true;
12936	}
12937
12938	bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
12939	if (!IsConstantEvaluatedBuiltinCall(E))
12940	return ExprEvaluatorBaseTy::VisitCallExpr(E);
12941	return VisitBuiltinCallExpr(E, BuiltinOp: E->getBuiltinCallee());
12942	}
12943
12944	static bool getBuiltinAlignArguments(const CallExpr *E, EvalInfo &Info,
12945	APValue &Val, APSInt &Alignment) {
12946	QualType SrcTy = E->getArg(Arg: 0)->getType();
12947	if (!getAlignmentArgument(E: E->getArg(Arg: 1), ForType: SrcTy, Info, Alignment))
12948	return false;
12949	// Even though we are evaluating integer expressions we could get a pointer
12950	// argument for the __builtin_is_aligned() case.
12951	if (SrcTy->isPointerType()) {
12952	LValue Ptr;
12953	if (!EvaluatePointer(E: E->getArg(Arg: 0), Result&: Ptr, Info))
12954	return false;
12955	Ptr.moveInto(V&: Val);
12956	} else if (!SrcTy->isIntegralOrEnumerationType()) {
12957	Info.FFDiag(E: E->getArg(Arg: 0));
12958	return false;
12959	} else {
12960	APSInt SrcInt;
12961	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: SrcInt, Info))
12962	return false;
12963	assert(SrcInt.getBitWidth() >= Alignment.getBitWidth() &&
12964	"Bit widths must be the same");
12965	Val = APValue(SrcInt);
12966	}
12967	assert(Val.hasValue());
12968	return true;
12969	}
12970
12971	bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
12972	unsigned BuiltinOp) {
12973	switch (BuiltinOp) {
12974	default:
12975	return false;
12976
12977	case Builtin::BI__builtin_dynamic_object_size:
12978	case Builtin::BI__builtin_object_size: {
12979	// The type was checked when we built the expression.
12980	unsigned Type =
12981	E->getArg(Arg: 1)->EvaluateKnownConstInt(Ctx: Info.Ctx).getZExtValue();
12982	assert(Type <= 3 && "unexpected type");
12983
12984	uint64_t Size;
12985	if (tryEvaluateBuiltinObjectSize(E: E->getArg(Arg: 0), Type, Info, Size))
12986	return Success(Size, E);
12987
12988	if (E->getArg(Arg: 0)->HasSideEffects(Ctx: Info.Ctx))
12989	return Success((Type & 2) ? 0 : -1, E);
12990
12991	// Expression had no side effects, but we couldn't statically determine the
12992	// size of the referenced object.
12993	switch (Info.EvalMode) {
12994	case EvalInfo::EM_ConstantExpression:
12995	case EvalInfo::EM_ConstantFold:
12996	case EvalInfo::EM_IgnoreSideEffects:
12997	// Leave it to IR generation.
12998	return Error(E);
12999	case EvalInfo::EM_ConstantExpressionUnevaluated:
13000	// Reduce it to a constant now.
13001	return Success((Type & 2) ? 0 : -1, E);
13002	}
13003
13004	llvm_unreachable("unexpected EvalMode");
13005	}
13006
13007	case Builtin::BI__builtin_os_log_format_buffer_size: {
13008	analyze_os_log::OSLogBufferLayout Layout;
13009	analyze_os_log::computeOSLogBufferLayout(Ctx&: Info.Ctx, E, layout&: Layout);
13010	return Success(Layout.size().getQuantity(), E);
13011	}
13012
13013	case Builtin::BI__builtin_is_aligned: {
13014	APValue Src;
13015	APSInt Alignment;
13016	if (!getBuiltinAlignArguments(E, Info, Val&: Src, Alignment))
13017	return false;
13018	if (Src.isLValue()) {
13019	// If we evaluated a pointer, check the minimum known alignment.
13020	LValue Ptr;
13021	Ptr.setFrom(Ctx&: Info.Ctx, V: Src);
13022	CharUnits BaseAlignment = getBaseAlignment(Info, Value: Ptr);
13023	CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(offset: Ptr.Offset);
13024	// We can return true if the known alignment at the computed offset is
13025	// greater than the requested alignment.
13026	assert(PtrAlign.isPowerOfTwo());
13027	assert(Alignment.isPowerOf2());
13028	if (PtrAlign.getQuantity() >= Alignment)
13029	return Success(1, E);
13030	// If the alignment is not known to be sufficient, some cases could still
13031	// be aligned at run time. However, if the requested alignment is less or
13032	// equal to the base alignment and the offset is not aligned, we know that
13033	// the run-time value can never be aligned.
13034	if (BaseAlignment.getQuantity() >= Alignment &&
13035	PtrAlign.getQuantity() < Alignment)
13036	return Success(0, E);
13037	// Otherwise we can't infer whether the value is sufficiently aligned.
13038	// TODO: __builtin_is_aligned(__builtin_align_{down,up{(expr, N), N)
13039	// in cases where we can't fully evaluate the pointer.
13040	Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_compute)
13041	<< Alignment;
13042	return false;
13043	}
13044	assert(Src.isInt());
13045	return Success((Src.getInt() & (Alignment - 1)) == 0 ? 1 : 0, E);
13046	}
13047	case Builtin::BI__builtin_align_up: {
13048	APValue Src;
13049	APSInt Alignment;
13050	if (!getBuiltinAlignArguments(E, Info, Val&: Src, Alignment))
13051	return false;
13052	if (!Src.isInt())
13053	return Error(E);
13054	APSInt AlignedVal =
13055	APSInt((Src.getInt() + (Alignment - 1)) & ~(Alignment - 1),
13056	Src.getInt().isUnsigned());
13057	assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth());
13058	return Success(AlignedVal, E);
13059	}
13060	case Builtin::BI__builtin_align_down: {
13061	APValue Src;
13062	APSInt Alignment;
13063	if (!getBuiltinAlignArguments(E, Info, Val&: Src, Alignment))
13064	return false;
13065	if (!Src.isInt())
13066	return Error(E);
13067	APSInt AlignedVal =
13068	APSInt(Src.getInt() & ~(Alignment - 1), Src.getInt().isUnsigned());
13069	assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth());
13070	return Success(AlignedVal, E);
13071	}
13072
13073	case Builtin::BI__builtin_bitreverse8:
13074	case Builtin::BI__builtin_bitreverse16:
13075	case Builtin::BI__builtin_bitreverse32:
13076	case Builtin::BI__builtin_bitreverse64:
13077	case Builtin::BI__builtin_elementwise_bitreverse: {
13078	APSInt Val;
13079	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13080	return false;
13081
13082	return Success(Val.reverseBits(), E);
13083	}
13084
13085	case Builtin::BI__builtin_bswap16:
13086	case Builtin::BI__builtin_bswap32:
13087	case Builtin::BI__builtin_bswap64: {
13088	APSInt Val;
13089	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13090	return false;
13091
13092	return Success(Val.byteSwap(), E);
13093	}
13094
13095	case Builtin::BI__builtin_classify_type:
13096	return Success((int)EvaluateBuiltinClassifyType(E, LangOpts: Info.getLangOpts()), E);
13097
13098	case Builtin::BI__builtin_clrsb:
13099	case Builtin::BI__builtin_clrsbl:
13100	case Builtin::BI__builtin_clrsbll: {
13101	APSInt Val;
13102	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13103	return false;
13104
13105	return Success(Val.getBitWidth() - Val.getSignificantBits(), E);
13106	}
13107
13108	case Builtin::BI__builtin_clz:
13109	case Builtin::BI__builtin_clzl:
13110	case Builtin::BI__builtin_clzll:
13111	case Builtin::BI__builtin_clzs:
13112	case Builtin::BI__builtin_clzg:
13113	case Builtin::BI__lzcnt16: // Microsoft variants of count leading-zeroes
13114	case Builtin::BI__lzcnt:
13115	case Builtin::BI__lzcnt64: {
13116	APSInt Val;
13117	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13118	return false;
13119
13120	std::optional<APSInt> Fallback;
13121	if (BuiltinOp == Builtin::BI__builtin_clzg && E->getNumArgs() > 1) {
13122	APSInt FallbackTemp;
13123	if (!EvaluateInteger(E: E->getArg(Arg: 1), Result&: FallbackTemp, Info))
13124	return false;
13125	Fallback = FallbackTemp;
13126	}
13127
13128	if (!Val) {
13129	if (Fallback)
13130	return Success(*Fallback, E);
13131
13132	// When the argument is 0, the result of GCC builtins is undefined,
13133	// whereas for Microsoft intrinsics, the result is the bit-width of the
13134	// argument.
13135	bool ZeroIsUndefined = BuiltinOp != Builtin::BI__lzcnt16 &&
13136	BuiltinOp != Builtin::BI__lzcnt &&
13137	BuiltinOp != Builtin::BI__lzcnt64;
13138
13139	if (ZeroIsUndefined)
13140	return Error(E);
13141	}
13142
13143	return Success(Val.countl_zero(), E);
13144	}
13145
13146	case Builtin::BI__builtin_constant_p: {
13147	const Expr *Arg = E->getArg(Arg: 0);
13148	if (EvaluateBuiltinConstantP(Info, Arg))
13149	return Success(true, E);
13150	if (Info.InConstantContext || Arg->HasSideEffects(Ctx: Info.Ctx)) {
13151	// Outside a constant context, eagerly evaluate to false in the presence
13152	// of side-effects in order to avoid -Wunsequenced false-positives in
13153	// a branch on __builtin_constant_p(expr).
13154	return Success(false, E);
13155	}
13156	Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
13157	return false;
13158	}
13159
13160	case Builtin::BI__noop:
13161	// __noop always evaluates successfully and returns 0.
13162	return Success(0, E);
13163
13164	case Builtin::BI__builtin_is_constant_evaluated: {
13165	const auto *Callee = Info.CurrentCall->getCallee();
13166	if (Info.InConstantContext && !Info.CheckingPotentialConstantExpression &&
13167	(Info.CallStackDepth == 1 ||
13168	(Info.CallStackDepth == 2 && Callee->isInStdNamespace() &&
13169	Callee->getIdentifier() &&
13170	Callee->getIdentifier()->isStr("is_constant_evaluated")))) {
13171	// FIXME: Find a better way to avoid duplicated diagnostics.
13172	if (Info.EvalStatus.Diag)
13173	Info.report((Info.CallStackDepth == 1)
13174	? E->getExprLoc()
13175	: Info.CurrentCall->getCallRange().getBegin(),
13176	diag::warn_is_constant_evaluated_always_true_constexpr)
13177	<< (Info.CallStackDepth == 1 ? "__builtin_is_constant_evaluated"
13178	: "std::is_constant_evaluated");
13179	}
13180
13181	return Success(Info.InConstantContext, E);
13182	}
13183
13184	case Builtin::BI__builtin_is_within_lifetime:
13185	if (auto result = EvaluateBuiltinIsWithinLifetime(*this, E))
13186	return Success(*result, E);
13187	return false;
13188
13189	case Builtin::BI__builtin_ctz:
13190	case Builtin::BI__builtin_ctzl:
13191	case Builtin::BI__builtin_ctzll:
13192	case Builtin::BI__builtin_ctzs:
13193	case Builtin::BI__builtin_ctzg: {
13194	APSInt Val;
13195	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13196	return false;
13197
13198	std::optional<APSInt> Fallback;
13199	if (BuiltinOp == Builtin::BI__builtin_ctzg && E->getNumArgs() > 1) {
13200	APSInt FallbackTemp;
13201	if (!EvaluateInteger(E: E->getArg(Arg: 1), Result&: FallbackTemp, Info))
13202	return false;
13203	Fallback = FallbackTemp;
13204	}
13205
13206	if (!Val) {
13207	if (Fallback)
13208	return Success(*Fallback, E);
13209
13210	return Error(E);
13211	}
13212
13213	return Success(Val.countr_zero(), E);
13214	}
13215
13216	case Builtin::BI__builtin_eh_return_data_regno: {
13217	int Operand = E->getArg(Arg: 0)->EvaluateKnownConstInt(Ctx: Info.Ctx).getZExtValue();
13218	Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(RegNo: Operand);
13219	return Success(Operand, E);
13220	}
13221
13222	case Builtin::BI__builtin_expect:
13223	case Builtin::BI__builtin_expect_with_probability:
13224	return Visit(E->getArg(Arg: 0));
13225
13226	case Builtin::BI__builtin_ptrauth_string_discriminator: {
13227	const auto *Literal =
13228	cast<StringLiteral>(Val: E->getArg(Arg: 0)->IgnoreParenImpCasts());
13229	uint64_t Result = getPointerAuthStableSipHash(S: Literal->getString());
13230	return Success(Result, E);
13231	}
13232
13233	case Builtin::BI__builtin_ffs:
13234	case Builtin::BI__builtin_ffsl:
13235	case Builtin::BI__builtin_ffsll: {
13236	APSInt Val;
13237	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13238	return false;
13239
13240	unsigned N = Val.countr_zero();
13241	return Success(N == Val.getBitWidth() ? 0 : N + 1, E);
13242	}
13243
13244	case Builtin::BI__builtin_fpclassify: {
13245	APFloat Val(0.0);
13246	if (!EvaluateFloat(E: E->getArg(Arg: 5), Result&: Val, Info))
13247	return false;
13248	unsigned Arg;
13249	switch (Val.getCategory()) {
13250	case APFloat::fcNaN: Arg = 0; break;
13251	case APFloat::fcInfinity: Arg = 1; break;
13252	case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break;
13253	case APFloat::fcZero: Arg = 4; break;
13254	}
13255	return Visit(E->getArg(Arg));
13256	}
13257
13258	case Builtin::BI__builtin_isinf_sign: {
13259	APFloat Val(0.0);
13260	return EvaluateFloat(E: E->getArg(Arg: 0), Result&: Val, Info) &&
13261	Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E);
13262	}
13263
13264	case Builtin::BI__builtin_isinf: {
13265	APFloat Val(0.0);
13266	return EvaluateFloat(E: E->getArg(Arg: 0), Result&: Val, Info) &&
13267	Success(Val.isInfinity() ? 1 : 0, E);
13268	}
13269
13270	case Builtin::BI__builtin_isfinite: {
13271	APFloat Val(0.0);
13272	return EvaluateFloat(E: E->getArg(Arg: 0), Result&: Val, Info) &&
13273	Success(Val.isFinite() ? 1 : 0, E);
13274	}
13275
13276	case Builtin::BI__builtin_isnan: {
13277	APFloat Val(0.0);
13278	return EvaluateFloat(E: E->getArg(Arg: 0), Result&: Val, Info) &&
13279	Success(Val.isNaN() ? 1 : 0, E);
13280	}
13281
13282	case Builtin::BI__builtin_isnormal: {
13283	APFloat Val(0.0);
13284	return EvaluateFloat(E: E->getArg(Arg: 0), Result&: Val, Info) &&
13285	Success(Val.isNormal() ? 1 : 0, E);
13286	}
13287
13288	case Builtin::BI__builtin_issubnormal: {
13289	APFloat Val(0.0);
13290	return EvaluateFloat(E: E->getArg(Arg: 0), Result&: Val, Info) &&
13291	Success(Val.isDenormal() ? 1 : 0, E);
13292	}
13293
13294	case Builtin::BI__builtin_iszero: {
13295	APFloat Val(0.0);
13296	return EvaluateFloat(E: E->getArg(Arg: 0), Result&: Val, Info) &&
13297	Success(Val.isZero() ? 1 : 0, E);
13298	}
13299
13300	case Builtin::BI__builtin_signbit:
13301	case Builtin::BI__builtin_signbitf:
13302	case Builtin::BI__builtin_signbitl: {
13303	APFloat Val(0.0);
13304	return EvaluateFloat(E: E->getArg(Arg: 0), Result&: Val, Info) &&
13305	Success(Val.isNegative() ? 1 : 0, E);
13306	}
13307
13308	case Builtin::BI__builtin_isgreater:
13309	case Builtin::BI__builtin_isgreaterequal:
13310	case Builtin::BI__builtin_isless:
13311	case Builtin::BI__builtin_islessequal:
13312	case Builtin::BI__builtin_islessgreater:
13313	case Builtin::BI__builtin_isunordered: {
13314	APFloat LHS(0.0);
13315	APFloat RHS(0.0);
13316	if (!EvaluateFloat(E: E->getArg(Arg: 0), Result&: LHS, Info) ||
13317	!EvaluateFloat(E: E->getArg(Arg: 1), Result&: RHS, Info))
13318	return false;
13319
13320	return Success(
13321	[&] {
13322	switch (BuiltinOp) {
13323	case Builtin::BI__builtin_isgreater:
13324	return LHS > RHS;
13325	case Builtin::BI__builtin_isgreaterequal:
13326	return LHS >= RHS;
13327	case Builtin::BI__builtin_isless:
13328	return LHS < RHS;
13329	case Builtin::BI__builtin_islessequal:
13330	return LHS <= RHS;
13331	case Builtin::BI__builtin_islessgreater: {
13332	APFloat::cmpResult cmp = LHS.compare(RHS);
13333	return cmp == APFloat::cmpResult::cmpLessThan ||
13334	cmp == APFloat::cmpResult::cmpGreaterThan;
13335	}
13336	case Builtin::BI__builtin_isunordered:
13337	return LHS.compare(RHS) == APFloat::cmpResult::cmpUnordered;
13338	default:
13339	llvm_unreachable("Unexpected builtin ID: Should be a floating "
13340	"point comparison function");
13341	}
13342	}()
13343	? 1
13344	: 0,
13345	E);
13346	}
13347
13348	case Builtin::BI__builtin_issignaling: {
13349	APFloat Val(0.0);
13350	return EvaluateFloat(E: E->getArg(Arg: 0), Result&: Val, Info) &&
13351	Success(Val.isSignaling() ? 1 : 0, E);
13352	}
13353
13354	case Builtin::BI__builtin_isfpclass: {
13355	APSInt MaskVal;
13356	if (!EvaluateInteger(E: E->getArg(Arg: 1), Result&: MaskVal, Info))
13357	return false;
13358	unsigned Test = static_cast<llvm::FPClassTest>(MaskVal.getZExtValue());
13359	APFloat Val(0.0);
13360	return EvaluateFloat(E: E->getArg(Arg: 0), Result&: Val, Info) &&
13361	Success((Val.classify() & Test) ? 1 : 0, E);
13362	}
13363
13364	case Builtin::BI__builtin_parity:
13365	case Builtin::BI__builtin_parityl:
13366	case Builtin::BI__builtin_parityll: {
13367	APSInt Val;
13368	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13369	return false;
13370
13371	return Success(Val.popcount() % 2, E);
13372	}
13373
13374	case Builtin::BI__builtin_abs:
13375	case Builtin::BI__builtin_labs:
13376	case Builtin::BI__builtin_llabs: {
13377	APSInt Val;
13378	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13379	return false;
13380	if (Val == APSInt(APInt::getSignedMinValue(numBits: Val.getBitWidth()),
13381	/*IsUnsigned=*/false))
13382	return false;
13383	if (Val.isNegative())
13384	Val.negate();
13385	return Success(Val, E);
13386	}
13387
13388	case Builtin::BI__builtin_popcount:
13389	case Builtin::BI__builtin_popcountl:
13390	case Builtin::BI__builtin_popcountll:
13391	case Builtin::BI__builtin_popcountg:
13392	case Builtin::BI__builtin_elementwise_popcount:
13393	case Builtin::BI__popcnt16: // Microsoft variants of popcount
13394	case Builtin::BI__popcnt:
13395	case Builtin::BI__popcnt64: {
13396	APSInt Val;
13397	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13398	return false;
13399
13400	return Success(Val.popcount(), E);
13401	}
13402
13403	case Builtin::BI__builtin_rotateleft8:
13404	case Builtin::BI__builtin_rotateleft16:
13405	case Builtin::BI__builtin_rotateleft32:
13406	case Builtin::BI__builtin_rotateleft64:
13407	case Builtin::BI_rotl8: // Microsoft variants of rotate right
13408	case Builtin::BI_rotl16:
13409	case Builtin::BI_rotl:
13410	case Builtin::BI_lrotl:
13411	case Builtin::BI_rotl64: {
13412	APSInt Val, Amt;
13413	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info) ||
13414	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: Amt, Info))
13415	return false;
13416
13417	return Success(Val.rotl(rotateAmt: Amt.urem(RHS: Val.getBitWidth())), E);
13418	}
13419
13420	case Builtin::BI__builtin_rotateright8:
13421	case Builtin::BI__builtin_rotateright16:
13422	case Builtin::BI__builtin_rotateright32:
13423	case Builtin::BI__builtin_rotateright64:
13424	case Builtin::BI_rotr8: // Microsoft variants of rotate right
13425	case Builtin::BI_rotr16:
13426	case Builtin::BI_rotr:
13427	case Builtin::BI_lrotr:
13428	case Builtin::BI_rotr64: {
13429	APSInt Val, Amt;
13430	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info) ||
13431	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: Amt, Info))
13432	return false;
13433
13434	return Success(Val.rotr(rotateAmt: Amt.urem(RHS: Val.getBitWidth())), E);
13435	}
13436
13437	case Builtin::BI__builtin_elementwise_add_sat: {
13438	APSInt LHS, RHS;
13439	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: LHS, Info) ||
13440	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: RHS, Info))
13441	return false;
13442
13443	APInt Result = LHS.isSigned() ? LHS.sadd_sat(RHS) : LHS.uadd_sat(RHS);
13444	return Success(APSInt(Result, !LHS.isSigned()), E);
13445	}
13446	case Builtin::BI__builtin_elementwise_sub_sat: {
13447	APSInt LHS, RHS;
13448	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: LHS, Info) ||
13449	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: RHS, Info))
13450	return false;
13451
13452	APInt Result = LHS.isSigned() ? LHS.ssub_sat(RHS) : LHS.usub_sat(RHS);
13453	return Success(APSInt(Result, !LHS.isSigned()), E);
13454	}
13455
13456	case Builtin::BIstrlen:
13457	case Builtin::BIwcslen:
13458	// A call to strlen is not a constant expression.
13459	if (Info.getLangOpts().CPlusPlus11)
13460	Info.CCEDiag(E, diag::note_constexpr_invalid_function)
13461	<< /*isConstexpr*/ 0 << /*isConstructor*/ 0
13462	<< Info.Ctx.BuiltinInfo.getQuotedName(BuiltinOp);
13463	else
13464	Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
13465	[[fallthrough]];
13466	case Builtin::BI__builtin_strlen:
13467	case Builtin::BI__builtin_wcslen: {
13468	// As an extension, we support __builtin_strlen() as a constant expression,
13469	// and support folding strlen() to a constant.
13470	uint64_t StrLen;
13471	if (EvaluateBuiltinStrLen(E: E->getArg(Arg: 0), Result&: StrLen, Info))
13472	return Success(StrLen, E);
13473	return false;
13474	}
13475
13476	case Builtin::BIstrcmp:
13477	case Builtin::BIwcscmp:
13478	case Builtin::BIstrncmp:
13479	case Builtin::BIwcsncmp:
13480	case Builtin::BImemcmp:
13481	case Builtin::BIbcmp:
13482	case Builtin::BIwmemcmp:
13483	// A call to strlen is not a constant expression.
13484	if (Info.getLangOpts().CPlusPlus11)
13485	Info.CCEDiag(E, diag::note_constexpr_invalid_function)
13486	<< /*isConstexpr*/ 0 << /*isConstructor*/ 0
13487	<< Info.Ctx.BuiltinInfo.getQuotedName(BuiltinOp);
13488	else
13489	Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
13490	[[fallthrough]];
13491	case Builtin::BI__builtin_strcmp:
13492	case Builtin::BI__builtin_wcscmp:
13493	case Builtin::BI__builtin_strncmp:
13494	case Builtin::BI__builtin_wcsncmp:
13495	case Builtin::BI__builtin_memcmp:
13496	case Builtin::BI__builtin_bcmp:
13497	case Builtin::BI__builtin_wmemcmp: {
13498	LValue String1, String2;
13499	if (!EvaluatePointer(E: E->getArg(Arg: 0), Result&: String1, Info) ||
13500	!EvaluatePointer(E: E->getArg(Arg: 1), Result&: String2, Info))
13501	return false;
13502
13503	uint64_t MaxLength = uint64_t(-1);
13504	if (BuiltinOp != Builtin::BIstrcmp &&
13505	BuiltinOp != Builtin::BIwcscmp &&
13506	BuiltinOp != Builtin::BI__builtin_strcmp &&
13507	BuiltinOp != Builtin::BI__builtin_wcscmp) {
13508	APSInt N;
13509	if (!EvaluateInteger(E: E->getArg(Arg: 2), Result&: N, Info))
13510	return false;
13511	MaxLength = N.getZExtValue();
13512	}
13513
13514	// Empty substrings compare equal by definition.
13515	if (MaxLength == 0u)
13516	return Success(0, E);
13517
13518	if (!String1.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
13519	!String2.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
13520	String1.Designator.Invalid || String2.Designator.Invalid)
13521	return false;
13522
13523	QualType CharTy1 = String1.Designator.getType(Info.Ctx);
13524	QualType CharTy2 = String2.Designator.getType(Info.Ctx);
13525
13526	bool IsRawByte = BuiltinOp == Builtin::BImemcmp ||
13527	BuiltinOp == Builtin::BIbcmp ||
13528	BuiltinOp == Builtin::BI__builtin_memcmp ||
13529	BuiltinOp == Builtin::BI__builtin_bcmp;
13530
13531	assert(IsRawByte ||
13532	(Info.Ctx.hasSameUnqualifiedType(
13533	CharTy1, E->getArg(0)->getType()->getPointeeType()) &&
13534	Info.Ctx.hasSameUnqualifiedType(CharTy1, CharTy2)));
13535
13536	// For memcmp, allow comparing any arrays of '[[un]signed] char' or
13537	// 'char8_t', but no other types.
13538	if (IsRawByte &&
13539	!(isOneByteCharacterType(T: CharTy1) && isOneByteCharacterType(T: CharTy2))) {
13540	// FIXME: Consider using our bit_cast implementation to support this.
13541	Info.FFDiag(E, diag::note_constexpr_memcmp_unsupported)
13542	<< Info.Ctx.BuiltinInfo.getQuotedName(BuiltinOp) << CharTy1
13543	<< CharTy2;
13544	return false;
13545	}
13546
13547	const auto &ReadCurElems = [&](APValue &Char1, APValue &Char2) {
13548	return handleLValueToRValueConversion(Info, E, CharTy1, String1, Char1) &&
13549	handleLValueToRValueConversion(Info, E, CharTy2, String2, Char2) &&
13550	Char1.isInt() && Char2.isInt();
13551	};
13552	const auto &AdvanceElems = [&] {
13553	return HandleLValueArrayAdjustment(Info, E, String1, CharTy1, 1) &&
13554	HandleLValueArrayAdjustment(Info, E, String2, CharTy2, 1);
13555	};
13556
13557	bool StopAtNull =
13558	(BuiltinOp != Builtin::BImemcmp && BuiltinOp != Builtin::BIbcmp &&
13559	BuiltinOp != Builtin::BIwmemcmp &&
13560	BuiltinOp != Builtin::BI__builtin_memcmp &&
13561	BuiltinOp != Builtin::BI__builtin_bcmp &&
13562	BuiltinOp != Builtin::BI__builtin_wmemcmp);
13563	bool IsWide = BuiltinOp == Builtin::BIwcscmp ||
13564	BuiltinOp == Builtin::BIwcsncmp ||
13565	BuiltinOp == Builtin::BIwmemcmp ||
13566	BuiltinOp == Builtin::BI__builtin_wcscmp ||
13567	BuiltinOp == Builtin::BI__builtin_wcsncmp ||
13568	BuiltinOp == Builtin::BI__builtin_wmemcmp;
13569
13570	for (; MaxLength; --MaxLength) {
13571	APValue Char1, Char2;
13572	if (!ReadCurElems(Char1, Char2))
13573	return false;
13574	if (Char1.getInt().ne(RHS: Char2.getInt())) {
13575	if (IsWide) // wmemcmp compares with wchar_t signedness.
13576	return Success(Char1.getInt() < Char2.getInt() ? -1 : 1, E);
13577	// memcmp always compares unsigned chars.
13578	return Success(Char1.getInt().ult(RHS: Char2.getInt()) ? -1 : 1, E);
13579	}
13580	if (StopAtNull && !Char1.getInt())
13581	return Success(0, E);
13582	assert(!(StopAtNull && !Char2.getInt()));
13583	if (!AdvanceElems())
13584	return false;
13585	}
13586	// We hit the strncmp / memcmp limit.
13587	return Success(0, E);
13588	}
13589
13590	case Builtin::BI__atomic_always_lock_free:
13591	case Builtin::BI__atomic_is_lock_free:
13592	case Builtin::BI__c11_atomic_is_lock_free: {
13593	APSInt SizeVal;
13594	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: SizeVal, Info))
13595	return false;
13596
13597	// For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power
13598	// of two less than or equal to the maximum inline atomic width, we know it
13599	// is lock-free. If the size isn't a power of two, or greater than the
13600	// maximum alignment where we promote atomics, we know it is not lock-free
13601	// (at least not in the sense of atomic_is_lock_free). Otherwise,
13602	// the answer can only be determined at runtime; for example, 16-byte
13603	// atomics have lock-free implementations on some, but not all,
13604	// x86-64 processors.
13605
13606	// Check power-of-two.
13607	CharUnits Size = CharUnits::fromQuantity(Quantity: SizeVal.getZExtValue());
13608	if (Size.isPowerOfTwo()) {
13609	// Check against inlining width.
13610	unsigned InlineWidthBits =
13611	Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth();
13612	if (Size <= Info.Ctx.toCharUnitsFromBits(BitSize: InlineWidthBits)) {
13613	if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free ||
13614	Size == CharUnits::One())
13615	return Success(1, E);
13616
13617	// If the pointer argument can be evaluated to a compile-time constant
13618	// integer (or nullptr), check if that value is appropriately aligned.
13619	const Expr *PtrArg = E->getArg(Arg: 1);
13620	Expr::EvalResult ExprResult;
13621	APSInt IntResult;
13622	if (PtrArg->EvaluateAsRValue(Result&: ExprResult, Ctx: Info.Ctx) &&
13623	ExprResult.Val.toIntegralConstant(Result&: IntResult, SrcTy: PtrArg->getType(),
13624	Ctx: Info.Ctx) &&
13625	IntResult.isAligned(A: Size.getAsAlign()))
13626	return Success(1, E);
13627
13628	// Otherwise, check if the type's alignment against Size.
13629	if (auto *ICE = dyn_cast<ImplicitCastExpr>(Val: PtrArg)) {
13630	// Drop the potential implicit-cast to 'const volatile void*', getting
13631	// the underlying type.
13632	if (ICE->getCastKind() == CK_BitCast)
13633	PtrArg = ICE->getSubExpr();
13634	}
13635
13636	if (auto PtrTy = PtrArg->getType()->getAs<PointerType>()) {
13637	QualType PointeeType = PtrTy->getPointeeType();
13638	if (!PointeeType->isIncompleteType() &&
13639	Info.Ctx.getTypeAlignInChars(T: PointeeType) >= Size) {
13640	// OK, we will inline operations on this object.
13641	return Success(1, E);
13642	}
13643	}
13644	}
13645	}
13646
13647	return BuiltinOp == Builtin::BI__atomic_always_lock_free ?
13648	Success(0, E) : Error(E);
13649	}
13650	case Builtin::BI__builtin_addcb:
13651	case Builtin::BI__builtin_addcs:
13652	case Builtin::BI__builtin_addc:
13653	case Builtin::BI__builtin_addcl:
13654	case Builtin::BI__builtin_addcll:
13655	case Builtin::BI__builtin_subcb:
13656	case Builtin::BI__builtin_subcs:
13657	case Builtin::BI__builtin_subc:
13658	case Builtin::BI__builtin_subcl:
13659	case Builtin::BI__builtin_subcll: {
13660	LValue CarryOutLValue;
13661	APSInt LHS, RHS, CarryIn, CarryOut, Result;
13662	QualType ResultType = E->getArg(Arg: 0)->getType();
13663	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: LHS, Info) ||
13664	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: RHS, Info) ||
13665	!EvaluateInteger(E: E->getArg(Arg: 2), Result&: CarryIn, Info) ||
13666	!EvaluatePointer(E: E->getArg(Arg: 3), Result&: CarryOutLValue, Info))
13667	return false;
13668	// Copy the number of bits and sign.
13669	Result = LHS;
13670	CarryOut = LHS;
13671
13672	bool FirstOverflowed = false;
13673	bool SecondOverflowed = false;
13674	switch (BuiltinOp) {
13675	default:
13676	llvm_unreachable("Invalid value for BuiltinOp");
13677	case Builtin::BI__builtin_addcb:
13678	case Builtin::BI__builtin_addcs:
13679	case Builtin::BI__builtin_addc:
13680	case Builtin::BI__builtin_addcl:
13681	case Builtin::BI__builtin_addcll:
13682	Result =
13683	LHS.uadd_ov(RHS, Overflow&: FirstOverflowed).uadd_ov(RHS: CarryIn, Overflow&: SecondOverflowed);
13684	break;
13685	case Builtin::BI__builtin_subcb:
13686	case Builtin::BI__builtin_subcs:
13687	case Builtin::BI__builtin_subc:
13688	case Builtin::BI__builtin_subcl:
13689	case Builtin::BI__builtin_subcll:
13690	Result =
13691	LHS.usub_ov(RHS, Overflow&: FirstOverflowed).usub_ov(RHS: CarryIn, Overflow&: SecondOverflowed);
13692	break;
13693	}
13694
13695	// It is possible for both overflows to happen but CGBuiltin uses an OR so
13696	// this is consistent.
13697	CarryOut = (uint64_t)(FirstOverflowed | SecondOverflowed);
13698	APValue APV{CarryOut};
13699	if (!handleAssignment(Info, E, CarryOutLValue, ResultType, APV))
13700	return false;
13701	return Success(Result, E);
13702	}
13703	case Builtin::BI__builtin_add_overflow:
13704	case Builtin::BI__builtin_sub_overflow:
13705	case Builtin::BI__builtin_mul_overflow:
13706	case Builtin::BI__builtin_sadd_overflow:
13707	case Builtin::BI__builtin_uadd_overflow:
13708	case Builtin::BI__builtin_uaddl_overflow:
13709	case Builtin::BI__builtin_uaddll_overflow:
13710	case Builtin::BI__builtin_usub_overflow:
13711	case Builtin::BI__builtin_usubl_overflow:
13712	case Builtin::BI__builtin_usubll_overflow:
13713	case Builtin::BI__builtin_umul_overflow:
13714	case Builtin::BI__builtin_umull_overflow:
13715	case Builtin::BI__builtin_umulll_overflow:
13716	case Builtin::BI__builtin_saddl_overflow:
13717	case Builtin::BI__builtin_saddll_overflow:
13718	case Builtin::BI__builtin_ssub_overflow:
13719	case Builtin::BI__builtin_ssubl_overflow:
13720	case Builtin::BI__builtin_ssubll_overflow:
13721	case Builtin::BI__builtin_smul_overflow:
13722	case Builtin::BI__builtin_smull_overflow:
13723	case Builtin::BI__builtin_smulll_overflow: {
13724	LValue ResultLValue;
13725	APSInt LHS, RHS;
13726
13727	QualType ResultType = E->getArg(Arg: 2)->getType()->getPointeeType();
13728	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: LHS, Info) ||
13729	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: RHS, Info) ||
13730	!EvaluatePointer(E: E->getArg(Arg: 2), Result&: ResultLValue, Info))
13731	return false;
13732
13733	APSInt Result;
13734	bool DidOverflow = false;
13735
13736	// If the types don't have to match, enlarge all 3 to the largest of them.
13737	if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
13738	BuiltinOp == Builtin::BI__builtin_sub_overflow ||
13739	BuiltinOp == Builtin::BI__builtin_mul_overflow) {
13740	bool IsSigned = LHS.isSigned() || RHS.isSigned() ||
13741	ResultType->isSignedIntegerOrEnumerationType();
13742	bool AllSigned = LHS.isSigned() && RHS.isSigned() &&
13743	ResultType->isSignedIntegerOrEnumerationType();
13744	uint64_t LHSSize = LHS.getBitWidth();
13745	uint64_t RHSSize = RHS.getBitWidth();
13746	uint64_t ResultSize = Info.Ctx.getTypeSize(T: ResultType);
13747	uint64_t MaxBits = std::max(a: std::max(a: LHSSize, b: RHSSize), b: ResultSize);
13748
13749	// Add an additional bit if the signedness isn't uniformly agreed to. We
13750	// could do this ONLY if there is a signed and an unsigned that both have
13751	// MaxBits, but the code to check that is pretty nasty. The issue will be
13752	// caught in the shrink-to-result later anyway.
13753	if (IsSigned && !AllSigned)
13754	++MaxBits;
13755
13756	LHS = APSInt(LHS.extOrTrunc(width: MaxBits), !IsSigned);
13757	RHS = APSInt(RHS.extOrTrunc(width: MaxBits), !IsSigned);
13758	Result = APSInt(MaxBits, !IsSigned);
13759	}
13760
13761	// Find largest int.
13762	switch (BuiltinOp) {
13763	default:
13764	llvm_unreachable("Invalid value for BuiltinOp");
13765	case Builtin::BI__builtin_add_overflow:
13766	case Builtin::BI__builtin_sadd_overflow:
13767	case Builtin::BI__builtin_saddl_overflow:
13768	case Builtin::BI__builtin_saddll_overflow:
13769	case Builtin::BI__builtin_uadd_overflow:
13770	case Builtin::BI__builtin_uaddl_overflow:
13771	case Builtin::BI__builtin_uaddll_overflow:
13772	Result = LHS.isSigned() ? LHS.sadd_ov(RHS, Overflow&: DidOverflow)
13773	: LHS.uadd_ov(RHS, Overflow&: DidOverflow);
13774	break;
13775	case Builtin::BI__builtin_sub_overflow:
13776	case Builtin::BI__builtin_ssub_overflow:
13777	case Builtin::BI__builtin_ssubl_overflow:
13778	case Builtin::BI__builtin_ssubll_overflow:
13779	case Builtin::BI__builtin_usub_overflow:
13780	case Builtin::BI__builtin_usubl_overflow:
13781	case Builtin::BI__builtin_usubll_overflow:
13782	Result = LHS.isSigned() ? LHS.ssub_ov(RHS, Overflow&: DidOverflow)
13783	: LHS.usub_ov(RHS, Overflow&: DidOverflow);
13784	break;
13785	case Builtin::BI__builtin_mul_overflow:
13786	case Builtin::BI__builtin_smul_overflow:
13787	case Builtin::BI__builtin_smull_overflow:
13788	case Builtin::BI__builtin_smulll_overflow:
13789	case Builtin::BI__builtin_umul_overflow:
13790	case Builtin::BI__builtin_umull_overflow:
13791	case Builtin::BI__builtin_umulll_overflow:
13792	Result = LHS.isSigned() ? LHS.smul_ov(RHS, Overflow&: DidOverflow)
13793	: LHS.umul_ov(RHS, Overflow&: DidOverflow);
13794	break;
13795	}
13796
13797	// In the case where multiple sizes are allowed, truncate and see if
13798	// the values are the same.
13799	if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
13800	BuiltinOp == Builtin::BI__builtin_sub_overflow ||
13801	BuiltinOp == Builtin::BI__builtin_mul_overflow) {
13802	// APSInt doesn't have a TruncOrSelf, so we use extOrTrunc instead,
13803	// since it will give us the behavior of a TruncOrSelf in the case where
13804	// its parameter <= its size. We previously set Result to be at least the
13805	// type-size of the result, so getTypeSize(ResultType) <= Result.BitWidth
13806	// will work exactly like TruncOrSelf.
13807	APSInt Temp = Result.extOrTrunc(width: Info.Ctx.getTypeSize(T: ResultType));
13808	Temp.setIsSigned(ResultType->isSignedIntegerOrEnumerationType());
13809
13810	if (!APSInt::isSameValue(I1: Temp, I2: Result))
13811	DidOverflow = true;
13812	Result = Temp;
13813	}
13814
13815	APValue APV{Result};
13816	if (!handleAssignment(Info, E, ResultLValue, ResultType, APV))
13817	return false;
13818	return Success(DidOverflow, E);
13819	}
13820
13821	case Builtin::BI__builtin_reduce_add:
13822	case Builtin::BI__builtin_reduce_mul:
13823	case Builtin::BI__builtin_reduce_and:
13824	case Builtin::BI__builtin_reduce_or:
13825	case Builtin::BI__builtin_reduce_xor:
13826	case Builtin::BI__builtin_reduce_min:
13827	case Builtin::BI__builtin_reduce_max: {
13828	APValue Source;
13829	if (!EvaluateAsRValue(Info, E: E->getArg(Arg: 0), Result&: Source))
13830	return false;
13831
13832	unsigned SourceLen = Source.getVectorLength();
13833	APSInt Reduced = Source.getVectorElt(I: 0).getInt();
13834	for (unsigned EltNum = 1; EltNum < SourceLen; ++EltNum) {
13835	switch (BuiltinOp) {
13836	default:
13837	return false;
13838	case Builtin::BI__builtin_reduce_add: {
13839	if (!CheckedIntArithmetic(
13840	Info, E, Reduced, Source.getVectorElt(I: EltNum).getInt(),
13841	Reduced.getBitWidth() + 1, std::plus<APSInt>(), Reduced))
13842	return false;
13843	break;
13844	}
13845	case Builtin::BI__builtin_reduce_mul: {
13846	if (!CheckedIntArithmetic(
13847	Info, E, Reduced, Source.getVectorElt(I: EltNum).getInt(),
13848	Reduced.getBitWidth() * 2, std::multiplies<APSInt>(), Reduced))
13849	return false;
13850	break;
13851	}
13852	case Builtin::BI__builtin_reduce_and: {
13853	Reduced &= Source.getVectorElt(I: EltNum).getInt();
13854	break;
13855	}
13856	case Builtin::BI__builtin_reduce_or: {
13857	Reduced |= Source.getVectorElt(I: EltNum).getInt();
13858	break;
13859	}
13860	case Builtin::BI__builtin_reduce_xor: {
13861	Reduced ^= Source.getVectorElt(I: EltNum).getInt();
13862	break;
13863	}
13864	case Builtin::BI__builtin_reduce_min: {
13865	Reduced = std::min(a: Reduced, b: Source.getVectorElt(I: EltNum).getInt());
13866	break;
13867	}
13868	case Builtin::BI__builtin_reduce_max: {
13869	Reduced = std::max(a: Reduced, b: Source.getVectorElt(I: EltNum).getInt());
13870	break;
13871	}
13872	}
13873	}
13874
13875	return Success(Reduced, E);
13876	}
13877
13878	case clang::X86::BI__builtin_ia32_addcarryx_u32:
13879	case clang::X86::BI__builtin_ia32_addcarryx_u64:
13880	case clang::X86::BI__builtin_ia32_subborrow_u32:
13881	case clang::X86::BI__builtin_ia32_subborrow_u64: {
13882	LValue ResultLValue;
13883	APSInt CarryIn, LHS, RHS;
13884	QualType ResultType = E->getArg(Arg: 3)->getType()->getPointeeType();
13885	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: CarryIn, Info) ||
13886	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: LHS, Info) ||
13887	!EvaluateInteger(E: E->getArg(Arg: 2), Result&: RHS, Info) ||
13888	!EvaluatePointer(E: E->getArg(Arg: 3), Result&: ResultLValue, Info))
13889	return false;
13890
13891	bool IsAdd = BuiltinOp == clang::X86::BI__builtin_ia32_addcarryx_u32 ||
13892	BuiltinOp == clang::X86::BI__builtin_ia32_addcarryx_u64;
13893
13894	unsigned BitWidth = LHS.getBitWidth();
13895	unsigned CarryInBit = CarryIn.ugt(RHS: 0) ? 1 : 0;
13896	APInt ExResult =
13897	IsAdd
13898	? (LHS.zext(width: BitWidth + 1) + (RHS.zext(width: BitWidth + 1) + CarryInBit))
13899	: (LHS.zext(width: BitWidth + 1) - (RHS.zext(width: BitWidth + 1) + CarryInBit));
13900
13901	APInt Result = ExResult.extractBits(numBits: BitWidth, bitPosition: 0);
13902	uint64_t CarryOut = ExResult.extractBitsAsZExtValue(numBits: 1, bitPosition: BitWidth);
13903
13904	APValue APV{APSInt(Result, /*isUnsigned=*/true)};
13905	if (!handleAssignment(Info, E, ResultLValue, ResultType, APV))
13906	return false;
13907	return Success(CarryOut, E);
13908	}
13909
13910	case clang::X86::BI__builtin_ia32_bextr_u32:
13911	case clang::X86::BI__builtin_ia32_bextr_u64:
13912	case clang::X86::BI__builtin_ia32_bextri_u32:
13913	case clang::X86::BI__builtin_ia32_bextri_u64: {
13914	APSInt Val, Idx;
13915	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info) ||
13916	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: Idx, Info))
13917	return false;
13918
13919	unsigned BitWidth = Val.getBitWidth();
13920	uint64_t Shift = Idx.extractBitsAsZExtValue(numBits: 8, bitPosition: 0);
13921	uint64_t Length = Idx.extractBitsAsZExtValue(numBits: 8, bitPosition: 8);
13922	Length = Length > BitWidth ? BitWidth : Length;
13923
13924	// Handle out of bounds cases.
13925	if (Length == 0 || Shift >= BitWidth)
13926	return Success(0, E);
13927
13928	uint64_t Result = Val.getZExtValue() >> Shift;
13929	Result &= llvm::maskTrailingOnes<uint64_t>(N: Length);
13930	return Success(Result, E);
13931	}
13932
13933	case clang::X86::BI__builtin_ia32_bzhi_si:
13934	case clang::X86::BI__builtin_ia32_bzhi_di: {
13935	APSInt Val, Idx;
13936	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info) ||
13937	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: Idx, Info))
13938	return false;
13939
13940	unsigned BitWidth = Val.getBitWidth();
13941	unsigned Index = Idx.extractBitsAsZExtValue(numBits: 8, bitPosition: 0);
13942	if (Index < BitWidth)
13943	Val.clearHighBits(hiBits: BitWidth - Index);
13944	return Success(Val, E);
13945	}
13946
13947	case clang::X86::BI__builtin_ia32_lzcnt_u16:
13948	case clang::X86::BI__builtin_ia32_lzcnt_u32:
13949	case clang::X86::BI__builtin_ia32_lzcnt_u64: {
13950	APSInt Val;
13951	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13952	return false;
13953	return Success(Val.countLeadingZeros(), E);
13954	}
13955
13956	case clang::X86::BI__builtin_ia32_tzcnt_u16:
13957	case clang::X86::BI__builtin_ia32_tzcnt_u32:
13958	case clang::X86::BI__builtin_ia32_tzcnt_u64: {
13959	APSInt Val;
13960	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info))
13961	return false;
13962	return Success(Val.countTrailingZeros(), E);
13963	}
13964
13965	case clang::X86::BI__builtin_ia32_pdep_si:
13966	case clang::X86::BI__builtin_ia32_pdep_di: {
13967	APSInt Val, Msk;
13968	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info) ||
13969	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: Msk, Info))
13970	return false;
13971
13972	unsigned BitWidth = Val.getBitWidth();
13973	APInt Result = APInt::getZero(numBits: BitWidth);
13974	for (unsigned I = 0, P = 0; I != BitWidth; ++I)
13975	if (Msk[I])
13976	Result.setBitVal(BitPosition: I, BitValue: Val[P++]);
13977	return Success(Result, E);
13978	}
13979
13980	case clang::X86::BI__builtin_ia32_pext_si:
13981	case clang::X86::BI__builtin_ia32_pext_di: {
13982	APSInt Val, Msk;
13983	if (!EvaluateInteger(E: E->getArg(Arg: 0), Result&: Val, Info) ||
13984	!EvaluateInteger(E: E->getArg(Arg: 1), Result&: Msk, Info))
13985	return false;
13986
13987	unsigned BitWidth = Val.getBitWidth();
13988	APInt Result = APInt::getZero(numBits: BitWidth);
13989	for (unsigned I = 0, P = 0; I != BitWidth; ++I)
13990	if (Msk[I])
13991	Result.setBitVal(BitPosition: P++, BitValue: Val[I]);
13992	return Success(Result, E);
13993	}
13994	}
13995	}
13996
13997	/// Determine whether this is a pointer past the end of the complete
13998	/// object referred to by the lvalue.
13999	static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx,
14000	const LValue &LV) {
14001	// A null pointer can be viewed as being "past the end" but we don't
14002	// choose to look at it that way here.
14003	if (!LV.getLValueBase())
14004	return false;
14005
14006	// If the designator is valid and refers to a subobject, we're not pointing
14007	// past the end.
14008	if (!LV.getLValueDesignator().Invalid &&
14009	!LV.getLValueDesignator().isOnePastTheEnd())
14010	return false;
14011
14012	// A pointer to an incomplete type might be past-the-end if the type's size is
14013	// zero. We cannot tell because the type is incomplete.
14014	QualType Ty = getType(B: LV.getLValueBase());
14015	if (Ty->isIncompleteType())
14016	return true;
14017
14018	// Can't be past the end of an invalid object.
14019	if (LV.getLValueDesignator().Invalid)
14020	return false;
14021
14022	// We're a past-the-end pointer if we point to the byte after the object,
14023	// no matter what our type or path is.
14024	auto Size = Ctx.getTypeSizeInChars(T: Ty);
14025	return LV.getLValueOffset() == Size;
14026	}
14027
14028	namespace {
14029
14030	/// Data recursive integer evaluator of certain binary operators.
14031	///
14032	/// We use a data recursive algorithm for binary operators so that we are able
14033	/// to handle extreme cases of chained binary operators without causing stack
14034	/// overflow.
14035	class DataRecursiveIntBinOpEvaluator {
14036	struct EvalResult {
14037	APValue Val;
14038	bool Failed = false;
14039
14040	EvalResult() = default;
14041
14042	void swap(EvalResult &RHS) {
14043	Val.swap(RHS&: RHS.Val);
14044	Failed = RHS.Failed;
14045	RHS.Failed = false;
14046	}
14047	};
14048
14049	struct Job {
14050	const Expr *E;
14051	EvalResult LHSResult; // meaningful only for binary operator expression.
14052	enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind;
14053
14054	Job() = default;
14055	Job(Job &&) = default;
14056
14057	void startSpeculativeEval(EvalInfo &Info) {
14058	SpecEvalRAII = SpeculativeEvaluationRAII(Info);
14059	}
14060
14061	private:
14062	SpeculativeEvaluationRAII SpecEvalRAII;
14063	};
14064
14065	SmallVector<Job, 16> Queue;
14066
14067	IntExprEvaluator &IntEval;
14068	EvalInfo &Info;
14069	APValue &FinalResult;
14070
14071	public:
14072	DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result)
14073	: IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { }
14074
14075	/// True if \param E is a binary operator that we are going to handle
14076	/// data recursively.
14077	/// We handle binary operators that are comma, logical, or that have operands
14078	/// with integral or enumeration type.
14079	static bool shouldEnqueue(const BinaryOperator *E) {
14080	return E->getOpcode() == BO_Comma || E->isLogicalOp() ||
14081	(E->isPRValue() && E->getType()->isIntegralOrEnumerationType() &&
14082	E->getLHS()->getType()->isIntegralOrEnumerationType() &&
14083	E->getRHS()->getType()->isIntegralOrEnumerationType());
14084	}
14085
14086	bool Traverse(const BinaryOperator *E) {
14087	enqueue(E);
14088	EvalResult PrevResult;
14089	while (!Queue.empty())
14090	process(Result&: PrevResult);
14091
14092	if (PrevResult.Failed) return false;
14093
14094	FinalResult.swap(RHS&: PrevResult.Val);
14095	return true;
14096	}
14097
14098	private:
14099	bool Success(uint64_t Value, const Expr *E, APValue &Result) {
14100	return IntEval.Success(Value, E, Result);
14101	}
14102	bool Success(const APSInt &Value, const Expr *E, APValue &Result) {
14103	return IntEval.Success(SI: Value, E, Result);
14104	}
14105	bool Error(const Expr *E) {
14106	return IntEval.Error(E);
14107	}
14108	bool Error(const Expr *E, diag::kind D) {
14109	return IntEval.Error(E, D);
14110	}
14111
14112	OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
14113	return Info.CCEDiag(E, DiagId: D);
14114	}
14115
14116	// Returns true if visiting the RHS is necessary, false otherwise.
14117	bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
14118	bool &SuppressRHSDiags);
14119
14120	bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
14121	const BinaryOperator *E, APValue &Result);
14122
14123	void EvaluateExpr(const Expr *E, EvalResult &Result) {
14124	Result.Failed = !Evaluate(Result&: Result.Val, Info, E);
14125	if (Result.Failed)
14126	Result.Val = APValue();
14127	}
14128
14129	void process(EvalResult &Result);
14130
14131	void enqueue(const Expr *E) {
14132	E = E->IgnoreParens();
14133	Queue.resize(N: Queue.size()+1);
14134	Queue.back().E = E;
14135	Queue.back().Kind = Job::AnyExprKind;
14136	}
14137	};
14138
14139	}
14140
14141	bool DataRecursiveIntBinOpEvaluator::
14142	VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
14143	bool &SuppressRHSDiags) {
14144	if (E->getOpcode() == BO_Comma) {
14145	// Ignore LHS but note if we could not evaluate it.
14146	if (LHSResult.Failed)
14147	return Info.noteSideEffect();
14148	return true;
14149	}
14150
14151	if (E->isLogicalOp()) {
14152	bool LHSAsBool;
14153	if (!LHSResult.Failed && HandleConversionToBool(Val: LHSResult.Val, Result&: LHSAsBool)) {
14154	// We were able to evaluate the LHS, see if we can get away with not
14155	// evaluating the RHS: 0 && X -> 0, 1 || X -> 1
14156	if (LHSAsBool == (E->getOpcode() == BO_LOr)) {
14157	Success(LHSAsBool, E, LHSResult.Val);
14158	return false; // Ignore RHS
14159	}
14160	} else {
14161	LHSResult.Failed = true;
14162
14163	// Since we weren't able to evaluate the left hand side, it
14164	// might have had side effects.
14165	if (!Info.noteSideEffect())
14166	return false;
14167
14168	// We can't evaluate the LHS; however, sometimes the result
14169	// is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
14170	// Don't ignore RHS and suppress diagnostics from this arm.
14171	SuppressRHSDiags = true;
14172	}
14173
14174	return true;
14175	}
14176
14177	assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
14178	E->getRHS()->getType()->isIntegralOrEnumerationType());
14179
14180	if (LHSResult.Failed && !Info.noteFailure())
14181	return false; // Ignore RHS;
14182
14183	return true;
14184	}
14185
14186	static void addOrSubLValueAsInteger(APValue &LVal, const APSInt &Index,
14187	bool IsSub) {
14188	// Compute the new offset in the appropriate width, wrapping at 64 bits.
14189	// FIXME: When compiling for a 32-bit target, we should use 32-bit
14190	// offsets.
14191	assert(!LVal.hasLValuePath() && "have designator for integer lvalue");
14192	CharUnits &Offset = LVal.getLValueOffset();
14193	uint64_t Offset64 = Offset.getQuantity();
14194	uint64_t Index64 = Index.extOrTrunc(width: 64).getZExtValue();
14195	Offset = CharUnits::fromQuantity(Quantity: IsSub ? Offset64 - Index64
14196	: Offset64 + Index64);
14197	}
14198
14199	bool DataRecursiveIntBinOpEvaluator::
14200	VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
14201	const BinaryOperator *E, APValue &Result) {
14202	if (E->getOpcode() == BO_Comma) {
14203	if (RHSResult.Failed)
14204	return false;
14205	Result = RHSResult.Val;
14206	return true;
14207	}
14208
14209	if (E->isLogicalOp()) {
14210	bool lhsResult, rhsResult;
14211	bool LHSIsOK = HandleConversionToBool(Val: LHSResult.Val, Result&: lhsResult);
14212	bool RHSIsOK = HandleConversionToBool(Val: RHSResult.Val, Result&: rhsResult);
14213
14214	if (LHSIsOK) {
14215	if (RHSIsOK) {
14216	if (E->getOpcode() == BO_LOr)
14217	return Success(lhsResult || rhsResult, E, Result);
14218	else
14219	return Success(lhsResult && rhsResult, E, Result);
14220	}
14221	} else {
14222	if (RHSIsOK) {
14223	// We can't evaluate the LHS; however, sometimes the result
14224	// is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
14225	if (rhsResult == (E->getOpcode() == BO_LOr))
14226	return Success(rhsResult, E, Result);
14227	}
14228	}
14229
14230	return false;
14231	}
14232
14233	assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
14234	E->getRHS()->getType()->isIntegralOrEnumerationType());
14235
14236	if (LHSResult.Failed || RHSResult.Failed)
14237	return false;
14238
14239	const APValue &LHSVal = LHSResult.Val;
14240	const APValue &RHSVal = RHSResult.Val;
14241
14242	// Handle cases like (unsigned long)&a + 4.
14243	if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) {
14244	Result = LHSVal;
14245	addOrSubLValueAsInteger(LVal&: Result, Index: RHSVal.getInt(), IsSub: E->getOpcode() == BO_Sub);
14246	return true;
14247	}
14248
14249	// Handle cases like 4 + (unsigned long)&a
14250	if (E->getOpcode() == BO_Add &&
14251	RHSVal.isLValue() && LHSVal.isInt()) {
14252	Result = RHSVal;
14253	addOrSubLValueAsInteger(LVal&: Result, Index: LHSVal.getInt(), /*IsSub*/false);
14254	return true;
14255	}
14256
14257	if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) {
14258	// Handle (intptr_t)&&A - (intptr_t)&&B.
14259	if (!LHSVal.getLValueOffset().isZero() ||
14260	!RHSVal.getLValueOffset().isZero())
14261	return false;
14262	const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>();
14263	const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>();
14264	if (!LHSExpr || !RHSExpr)
14265	return false;
14266	const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(Val: LHSExpr);
14267	const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(Val: RHSExpr);
14268	if (!LHSAddrExpr || !RHSAddrExpr)
14269	return false;
14270	// Make sure both labels come from the same function.
14271	if (LHSAddrExpr->getLabel()->getDeclContext() !=
14272	RHSAddrExpr->getLabel()->getDeclContext())
14273	return false;
14274	Result = APValue(LHSAddrExpr, RHSAddrExpr);
14275	return true;
14276	}
14277
14278	// All the remaining cases expect both operands to be an integer
14279	if (!LHSVal.isInt() || !RHSVal.isInt())
14280	return Error(E);
14281
14282	// Set up the width and signedness manually, in case it can't be deduced
14283	// from the operation we're performing.
14284	// FIXME: Don't do this in the cases where we can deduce it.
14285	APSInt Value(Info.Ctx.getIntWidth(T: E->getType()),
14286	E->getType()->isUnsignedIntegerOrEnumerationType());
14287	if (!handleIntIntBinOp(Info, E, LHS: LHSVal.getInt(), Opcode: E->getOpcode(),
14288	RHS: RHSVal.getInt(), Result&: Value))
14289	return false;
14290	return Success(Value, E, Result);
14291	}
14292
14293	void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) {
14294	Job &job = Queue.back();
14295
14296	switch (job.Kind) {
14297	case Job::AnyExprKind: {
14298	if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(Val: job.E)) {
14299	if (shouldEnqueue(E: Bop)) {
14300	job.Kind = Job::BinOpKind;
14301	enqueue(E: Bop->getLHS());
14302	return;
14303	}
14304	}
14305
14306	EvaluateExpr(E: job.E, Result);
14307	Queue.pop_back();
14308	return;
14309	}
14310
14311	case Job::BinOpKind: {
14312	const BinaryOperator *Bop = cast<BinaryOperator>(Val: job.E);
14313	bool SuppressRHSDiags = false;
14314	if (!VisitBinOpLHSOnly(LHSResult&: Result, E: Bop, SuppressRHSDiags)) {
14315	Queue.pop_back();
14316	return;
14317	}
14318	if (SuppressRHSDiags)
14319	job.startSpeculativeEval(Info);
14320	job.LHSResult.swap(RHS&: Result);
14321	job.Kind = Job::BinOpVisitedLHSKind;
14322	enqueue(E: Bop->getRHS());
14323	return;
14324	}
14325
14326	case Job::BinOpVisitedLHSKind: {
14327	const BinaryOperator *Bop = cast<BinaryOperator>(Val: job.E);
14328	EvalResult RHS;
14329	RHS.swap(RHS&: Result);
14330	Result.Failed = !VisitBinOp(LHSResult: job.LHSResult, RHSResult: RHS, E: Bop, Result&: Result.Val);
14331	Queue.pop_back();
14332	return;
14333	}
14334	}
14335
14336	llvm_unreachable("Invalid Job::Kind!");
14337	}
14338
14339	namespace {
14340	enum class CmpResult {
14341	Unequal,
14342	Less,
14343	Equal,
14344	Greater,
14345	Unordered,
14346	};
14347	}
14348
14349	template <class SuccessCB, class AfterCB>
14350	static bool
14351	EvaluateComparisonBinaryOperator(EvalInfo &Info, const BinaryOperator *E,
14352	SuccessCB &&Success, AfterCB &&DoAfter) {
14353	assert(!E->isValueDependent());
14354	assert(E->isComparisonOp() && "expected comparison operator");
14355	assert((E->getOpcode() == BO_Cmp ||
14356	E->getType()->isIntegralOrEnumerationType()) &&
14357	"unsupported binary expression evaluation");
14358	auto Error = [&](const Expr *E) {
14359	Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
14360	return false;
14361	};
14362
14363	bool IsRelational = E->isRelationalOp() || E->getOpcode() == BO_Cmp;
14364	bool IsEquality = E->isEqualityOp();
14365
14366	QualType LHSTy = E->getLHS()->getType();
14367	QualType RHSTy = E->getRHS()->getType();
14368
14369	if (LHSTy->isIntegralOrEnumerationType() &&
14370	RHSTy->isIntegralOrEnumerationType()) {
14371	APSInt LHS, RHS;
14372	bool LHSOK = EvaluateInteger(E: E->getLHS(), Result&: LHS, Info);
14373	if (!LHSOK && !Info.noteFailure())
14374	return false;
14375	if (!EvaluateInteger(E: E->getRHS(), Result&: RHS, Info) || !LHSOK)
14376	return false;
14377	if (LHS < RHS)
14378	return Success(CmpResult::Less, E);
14379	if (LHS > RHS)
14380	return Success(CmpResult::Greater, E);
14381	return Success(CmpResult::Equal, E);
14382	}
14383
14384	if (LHSTy->isFixedPointType() || RHSTy->isFixedPointType()) {
14385	APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(Ty: LHSTy));
14386	APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(Ty: RHSTy));
14387
14388	bool LHSOK = EvaluateFixedPointOrInteger(E: E->getLHS(), Result&: LHSFX, Info);
14389	if (!LHSOK && !Info.noteFailure())
14390	return false;
14391	if (!EvaluateFixedPointOrInteger(E: E->getRHS(), Result&: RHSFX, Info) || !LHSOK)
14392	return false;
14393	if (LHSFX < RHSFX)
14394	return Success(CmpResult::Less, E);
14395	if (LHSFX > RHSFX)
14396	return Success(CmpResult::Greater, E);
14397	return Success(CmpResult::Equal, E);
14398	}
14399
14400	if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) {
14401	ComplexValue LHS, RHS;
14402	bool LHSOK;
14403	if (E->isAssignmentOp()) {
14404	LValue LV;
14405	EvaluateLValue(E: E->getLHS(), Result&: LV, Info);
14406	LHSOK = false;
14407	} else if (LHSTy->isRealFloatingType()) {
14408	LHSOK = EvaluateFloat(E: E->getLHS(), Result&: LHS.FloatReal, Info);
14409	if (LHSOK) {
14410	LHS.makeComplexFloat();
14411	LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics());
14412	}
14413	} else {
14414	LHSOK = EvaluateComplex(E: E->getLHS(), Res&: LHS, Info);
14415	}
14416	if (!LHSOK && !Info.noteFailure())
14417	return false;
14418
14419	if (E->getRHS()->getType()->isRealFloatingType()) {
14420	if (!EvaluateFloat(E: E->getRHS(), Result&: RHS.FloatReal, Info) || !LHSOK)
14421	return false;
14422	RHS.makeComplexFloat();
14423	RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics());
14424	} else if (!EvaluateComplex(E: E->getRHS(), Res&: RHS, Info) || !LHSOK)
14425	return false;
14426
14427	if (LHS.isComplexFloat()) {
14428	APFloat::cmpResult CR_r =
14429	LHS.getComplexFloatReal().compare(RHS: RHS.getComplexFloatReal());
14430	APFloat::cmpResult CR_i =
14431	LHS.getComplexFloatImag().compare(RHS: RHS.getComplexFloatImag());
14432	bool IsEqual = CR_r == APFloat::cmpEqual && CR_i == APFloat::cmpEqual;
14433	return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E);
14434	} else {
14435	assert(IsEquality && "invalid complex comparison");
14436	bool IsEqual = LHS.getComplexIntReal() == RHS.getComplexIntReal() &&
14437	LHS.getComplexIntImag() == RHS.getComplexIntImag();
14438	return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E);
14439	}
14440	}
14441
14442	if (LHSTy->isRealFloatingType() &&
14443	RHSTy->isRealFloatingType()) {
14444	APFloat RHS(0.0), LHS(0.0);
14445
14446	bool LHSOK = EvaluateFloat(E: E->getRHS(), Result&: RHS, Info);
14447	if (!LHSOK && !Info.noteFailure())
14448	return false;
14449
14450	if (!EvaluateFloat(E: E->getLHS(), Result&: LHS, Info) || !LHSOK)
14451	return false;
14452
14453	assert(E->isComparisonOp() && "Invalid binary operator!");
14454	llvm::APFloatBase::cmpResult APFloatCmpResult = LHS.compare(RHS);
14455	if (!Info.InConstantContext &&
14456	APFloatCmpResult == APFloat::cmpUnordered &&
14457	E->getFPFeaturesInEffect(LO: Info.Ctx.getLangOpts()).isFPConstrained()) {
14458	// Note: Compares may raise invalid in some cases involving NaN or sNaN.
14459	Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
14460	return false;
14461	}
14462	auto GetCmpRes = [&]() {
14463	switch (APFloatCmpResult) {
14464	case APFloat::cmpEqual:
14465	return CmpResult::Equal;
14466	case APFloat::cmpLessThan:
14467	return CmpResult::Less;
14468	case APFloat::cmpGreaterThan:
14469	return CmpResult::Greater;
14470	case APFloat::cmpUnordered:
14471	return CmpResult::Unordered;
14472	}
14473	llvm_unreachable("Unrecognised APFloat::cmpResult enum");
14474	};
14475	return Success(GetCmpRes(), E);
14476	}
14477
14478	if (LHSTy->isPointerType() && RHSTy->isPointerType()) {
14479	LValue LHSValue, RHSValue;
14480
14481	bool LHSOK = EvaluatePointer(E: E->getLHS(), Result&: LHSValue, Info);
14482	if (!LHSOK && !Info.noteFailure())
14483	return false;
14484
14485	if (!EvaluatePointer(E: E->getRHS(), Result&: RHSValue, Info) || !LHSOK)
14486	return false;
14487
14488	// If we have Unknown pointers we should fail if they are not global values.
14489	if (!(IsGlobalLValue(B: LHSValue.getLValueBase()) &&
14490	IsGlobalLValue(B: RHSValue.getLValueBase())) &&
14491	(LHSValue.AllowConstexprUnknown || RHSValue.AllowConstexprUnknown))
14492	return false;
14493
14494	// Reject differing bases from the normal codepath; we special-case
14495	// comparisons to null.
14496	if (!HasSameBase(A: LHSValue, B: RHSValue)) {
14497	auto DiagComparison = [&] (unsigned DiagID, bool Reversed = false) {
14498	std::string LHS = LHSValue.toString(Ctx&: Info.Ctx, T: E->getLHS()->getType());
14499	std::string RHS = RHSValue.toString(Ctx&: Info.Ctx, T: E->getRHS()->getType());
14500	Info.FFDiag(E, DiagID)
14501	<< (Reversed ? RHS : LHS) << (Reversed ? LHS : RHS);
14502	return false;
14503	};
14504	// Inequalities and subtractions between unrelated pointers have
14505	// unspecified or undefined behavior.
14506	if (!IsEquality)
14507	return DiagComparison(
14508	diag::note_constexpr_pointer_comparison_unspecified);
14509	// A constant address may compare equal to the address of a symbol.
14510	// The one exception is that address of an object cannot compare equal
14511	// to a null pointer constant.
14512	// TODO: Should we restrict this to actual null pointers, and exclude the
14513	// case of zero cast to pointer type?
14514	if ((!LHSValue.Base && !LHSValue.Offset.isZero()) ||
14515	(!RHSValue.Base && !RHSValue.Offset.isZero()))
14516	return DiagComparison(diag::note_constexpr_pointer_constant_comparison,
14517	!RHSValue.Base);
14518	// C++2c [intro.object]/10:
14519	// Two objects [...] may have the same address if [...] they are both
14520	// potentially non-unique objects.
14521	// C++2c [intro.object]/9:
14522	// An object is potentially non-unique if it is a string literal object,
14523	// the backing array of an initializer list, or a subobject thereof.
14524	//
14525	// This makes the comparison result unspecified, so it's not a constant
14526	// expression.
14527	//
14528	// TODO: Do we need to handle the initializer list case here?
14529	if (ArePotentiallyOverlappingStringLiterals(Info, LHSValue, RHSValue))
14530	return DiagComparison(diag::note_constexpr_literal_comparison);
14531	if (IsOpaqueConstantCall(LHSValue) || IsOpaqueConstantCall(RHSValue))
14532	return DiagComparison(diag::note_constexpr_opaque_call_comparison,
14533	!IsOpaqueConstantCall(LHSValue));
14534	// We can't tell whether weak symbols will end up pointing to the same
14535	// object.
14536	if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue))
14537	return DiagComparison(diag::note_constexpr_pointer_weak_comparison,
14538	!IsWeakLValue(LHSValue));
14539	// We can't compare the address of the start of one object with the
14540	// past-the-end address of another object, per C++ DR1652.
14541	if (LHSValue.Base && LHSValue.Offset.isZero() &&
14542	isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue))
14543	return DiagComparison(diag::note_constexpr_pointer_comparison_past_end,
14544	true);
14545	if (RHSValue.Base && RHSValue.Offset.isZero() &&
14546	isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue))
14547	return DiagComparison(diag::note_constexpr_pointer_comparison_past_end,
14548	false);
14549	// We can't tell whether an object is at the same address as another
14550	// zero sized object.
14551	if ((RHSValue.Base && isZeroSized(LHSValue)) ||
14552	(LHSValue.Base && isZeroSized(RHSValue)))
14553	return DiagComparison(
14554	diag::note_constexpr_pointer_comparison_zero_sized);
14555	return Success(CmpResult::Unequal, E);
14556	}
14557
14558	const CharUnits &LHSOffset = LHSValue.getLValueOffset();
14559	const CharUnits &RHSOffset = RHSValue.getLValueOffset();
14560
14561	SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
14562	SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
14563
14564	// C++11 [expr.rel]p2:
14565	// - If two pointers point to non-static data members of the same object,
14566	// or to subobjects or array elements fo such members, recursively, the
14567	// pointer to the later declared member compares greater provided the
14568	// two members have the same access control and provided their class is
14569	// not a union.
14570	// [...]
14571	// - Otherwise pointer comparisons are unspecified.
14572	if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && IsRelational) {
14573	bool WasArrayIndex;
14574	unsigned Mismatch = FindDesignatorMismatch(
14575	ObjType: getType(B: LHSValue.Base), A: LHSDesignator, B: RHSDesignator, WasArrayIndex);
14576	// At the point where the designators diverge, the comparison has a
14577	// specified value if:
14578	// - we are comparing array indices
14579	// - we are comparing fields of a union, or fields with the same access
14580	// Otherwise, the result is unspecified and thus the comparison is not a
14581	// constant expression.
14582	if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() &&
14583	Mismatch < RHSDesignator.Entries.size()) {
14584	const FieldDecl *LF = getAsField(E: LHSDesignator.Entries[Mismatch]);
14585	const FieldDecl *RF = getAsField(E: RHSDesignator.Entries[Mismatch]);
14586	if (!LF && !RF)
14587	Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes);
14588	else if (!LF)
14589	Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
14590	<< getAsBaseClass(LHSDesignator.Entries[Mismatch])
14591	<< RF->getParent() << RF;
14592	else if (!RF)
14593	Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
14594	<< getAsBaseClass(RHSDesignator.Entries[Mismatch])
14595	<< LF->getParent() << LF;
14596	else if (!LF->getParent()->isUnion() &&
14597	LF->getAccess() != RF->getAccess())
14598	Info.CCEDiag(E,
14599	diag::note_constexpr_pointer_comparison_differing_access)
14600	<< LF << LF->getAccess() << RF << RF->getAccess()
14601	<< LF->getParent();
14602	}
14603	}
14604
14605	// The comparison here must be unsigned, and performed with the same
14606	// width as the pointer.
14607	unsigned PtrSize = Info.Ctx.getTypeSize(T: LHSTy);
14608	uint64_t CompareLHS = LHSOffset.getQuantity();
14609	uint64_t CompareRHS = RHSOffset.getQuantity();
14610	assert(PtrSize <= 64 && "Unexpected pointer width");
14611	uint64_t Mask = ~0ULL >> (64 - PtrSize);
14612	CompareLHS &= Mask;
14613	CompareRHS &= Mask;
14614
14615	// If there is a base and this is a relational operator, we can only
14616	// compare pointers within the object in question; otherwise, the result
14617	// depends on where the object is located in memory.
14618	if (!LHSValue.Base.isNull() && IsRelational) {
14619	QualType BaseTy = getType(B: LHSValue.Base);
14620	if (BaseTy->isIncompleteType())
14621	return Error(E);
14622	CharUnits Size = Info.Ctx.getTypeSizeInChars(T: BaseTy);
14623	uint64_t OffsetLimit = Size.getQuantity();
14624	if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit)
14625	return Error(E);
14626	}
14627
14628	if (CompareLHS < CompareRHS)
14629	return Success(CmpResult::Less, E);
14630	if (CompareLHS > CompareRHS)
14631	return Success(CmpResult::Greater, E);
14632	return Success(CmpResult::Equal, E);
14633	}
14634
14635	if (LHSTy->isMemberPointerType()) {
14636	assert(IsEquality && "unexpected member pointer operation");
14637	assert(RHSTy->isMemberPointerType() && "invalid comparison");
14638
14639	MemberPtr LHSValue, RHSValue;
14640
14641	bool LHSOK = EvaluateMemberPointer(E: E->getLHS(), Result&: LHSValue, Info);
14642	if (!LHSOK && !Info.noteFailure())
14643	return false;
14644
14645	if (!EvaluateMemberPointer(E: E->getRHS(), Result&: RHSValue, Info) || !LHSOK)
14646	return false;
14647
14648	// If either operand is a pointer to a weak function, the comparison is not
14649	// constant.
14650	if (LHSValue.getDecl() && LHSValue.getDecl()->isWeak()) {
14651	Info.FFDiag(E, diag::note_constexpr_mem_pointer_weak_comparison)
14652	<< LHSValue.getDecl();
14653	return false;
14654	}
14655	if (RHSValue.getDecl() && RHSValue.getDecl()->isWeak()) {
14656	Info.FFDiag(E, diag::note_constexpr_mem_pointer_weak_comparison)
14657	<< RHSValue.getDecl();
14658	return false;
14659	}
14660
14661	// C++11 [expr.eq]p2:
14662	// If both operands are null, they compare equal. Otherwise if only one is
14663	// null, they compare unequal.
14664	if (!LHSValue.getDecl() || !RHSValue.getDecl()) {
14665	bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl();
14666	return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E);
14667	}
14668
14669	// Otherwise if either is a pointer to a virtual member function, the
14670	// result is unspecified.
14671	if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl()))
14672	if (MD->isVirtual())
14673	Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
14674	if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl()))
14675	if (MD->isVirtual())
14676	Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
14677
14678	// Otherwise they compare equal if and only if they would refer to the
14679	// same member of the same most derived object or the same subobject if
14680	// they were dereferenced with a hypothetical object of the associated
14681	// class type.
14682	bool Equal = LHSValue == RHSValue;
14683	return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E);
14684	}
14685
14686	if (LHSTy->isNullPtrType()) {
14687	assert(E->isComparisonOp() && "unexpected nullptr operation");
14688	assert(RHSTy->isNullPtrType() && "missing pointer conversion");
14689	// C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t
14690	// are compared, the result is true of the operator is <=, >= or ==, and
14691	// false otherwise.
14692	LValue Res;
14693	if (!EvaluatePointer(E: E->getLHS(), Result&: Res, Info) ||
14694	!EvaluatePointer(E: E->getRHS(), Result&: Res, Info))
14695	return false;
14696	return Success(CmpResult::Equal, E);
14697	}
14698
14699	return DoAfter();
14700	}
14701
14702	bool RecordExprEvaluator::VisitBinCmp(const BinaryOperator *E) {
14703	if (!CheckLiteralType(Info, E))
14704	return false;
14705
14706	auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) {
14707	ComparisonCategoryResult CCR;
14708	switch (CR) {
14709	case CmpResult::Unequal:
14710	llvm_unreachable("should never produce Unequal for three-way comparison");
14711	case CmpResult::Less:
14712	CCR = ComparisonCategoryResult::Less;
14713	break;
14714	case CmpResult::Equal:
14715	CCR = ComparisonCategoryResult::Equal;
14716	break;
14717	case CmpResult::Greater:
14718	CCR = ComparisonCategoryResult::Greater;
14719	break;
14720	case CmpResult::Unordered:
14721	CCR = ComparisonCategoryResult::Unordered;
14722	break;
14723	}
14724	// Evaluation succeeded. Lookup the information for the comparison category
14725	// type and fetch the VarDecl for the result.
14726	const ComparisonCategoryInfo &CmpInfo =
14727	Info.Ctx.CompCategories.getInfoForType(Ty: E->getType());
14728	const VarDecl *VD = CmpInfo.getValueInfo(ValueKind: CmpInfo.makeWeakResult(Res: CCR))->VD;
14729	// Check and evaluate the result as a constant expression.
14730	LValue LV;
14731	LV.set(VD);
14732	if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
14733	return false;
14734	return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result,
14735	ConstantExprKind::Normal);
14736	};
14737	return EvaluateComparisonBinaryOperator(Info, E, Success&: OnSuccess, DoAfter: [&]() {
14738	return ExprEvaluatorBaseTy::VisitBinCmp(E);
14739	});
14740	}
14741
14742	bool RecordExprEvaluator::VisitCXXParenListInitExpr(
14743	const CXXParenListInitExpr *E) {
14744	return VisitCXXParenListOrInitListExpr(E, E->getInitExprs());
14745	}
14746
14747	bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
14748	// We don't support assignment in C. C++ assignments don't get here because
14749	// assignment is an lvalue in C++.
14750	if (E->isAssignmentOp()) {
14751	Error(E);
14752	if (!Info.noteFailure())
14753	return false;
14754	}
14755
14756	if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E))
14757	return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E);
14758
14759	assert((!E->getLHS()->getType()->isIntegralOrEnumerationType() ||
14760	!E->getRHS()->getType()->isIntegralOrEnumerationType()) &&
14761	"DataRecursiveIntBinOpEvaluator should have handled integral types");
14762
14763	if (E->isComparisonOp()) {
14764	// Evaluate builtin binary comparisons by evaluating them as three-way
14765	// comparisons and then translating the result.
14766	auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) {
14767	assert((CR != CmpResult::Unequal || E->isEqualityOp()) &&
14768	"should only produce Unequal for equality comparisons");
14769	bool IsEqual = CR == CmpResult::Equal,
14770	IsLess = CR == CmpResult::Less,
14771	IsGreater = CR == CmpResult::Greater;
14772	auto Op = E->getOpcode();
14773	switch (Op) {
14774	default:
14775	llvm_unreachable("unsupported binary operator");
14776	case BO_EQ:
14777	case BO_NE:
14778	return Success(IsEqual == (Op == BO_EQ), E);
14779	case BO_LT:
14780	return Success(IsLess, E);
14781	case BO_GT:
14782	return Success(IsGreater, E);
14783	case BO_LE:
14784	return Success(IsEqual || IsLess, E);
14785	case BO_GE:
14786	return Success(IsEqual || IsGreater, E);
14787	}
14788	};
14789	return EvaluateComparisonBinaryOperator(Info, E, Success&: OnSuccess, DoAfter: [&]() {
14790	return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
14791	});
14792	}
14793
14794	QualType LHSTy = E->getLHS()->getType();
14795	QualType RHSTy = E->getRHS()->getType();
14796
14797	if (LHSTy->isPointerType() && RHSTy->isPointerType() &&
14798	E->getOpcode() == BO_Sub) {
14799	LValue LHSValue, RHSValue;
14800
14801	bool LHSOK = EvaluatePointer(E: E->getLHS(), Result&: LHSValue, Info);
14802	if (!LHSOK && !Info.noteFailure())
14803	return false;
14804
14805	if (!EvaluatePointer(E: E->getRHS(), Result&: RHSValue, Info) || !LHSOK)
14806	return false;
14807
14808	// Reject differing bases from the normal codepath; we special-case
14809	// comparisons to null.
14810	if (!HasSameBase(A: LHSValue, B: RHSValue)) {
14811	const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr *>();
14812	const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr *>();
14813
14814	auto DiagArith = [&](unsigned DiagID) {
14815	std::string LHS = LHSValue.toString(Ctx&: Info.Ctx, T: E->getLHS()->getType());
14816	std::string RHS = RHSValue.toString(Ctx&: Info.Ctx, T: E->getRHS()->getType());
14817	Info.FFDiag(E, DiagID) << LHS << RHS;
14818	if (LHSExpr && LHSExpr == RHSExpr)
14819	Info.Note(LHSExpr->getExprLoc(),
14820	diag::note_constexpr_repeated_literal_eval)
14821	<< LHSExpr->getSourceRange();
14822	return false;
14823	};
14824
14825	if (!LHSExpr || !RHSExpr)
14826	return DiagArith(diag::note_constexpr_pointer_arith_unspecified);
14827
14828	if (ArePotentiallyOverlappingStringLiterals(Info, LHSValue, RHSValue))
14829	return DiagArith(diag::note_constexpr_literal_arith);
14830
14831	const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(Val: LHSExpr);
14832	const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(Val: RHSExpr);
14833	if (!LHSAddrExpr || !RHSAddrExpr)
14834	return Error(E);
14835	// Make sure both labels come from the same function.
14836	if (LHSAddrExpr->getLabel()->getDeclContext() !=
14837	RHSAddrExpr->getLabel()->getDeclContext())
14838	return Error(E);
14839	return Success(APValue(LHSAddrExpr, RHSAddrExpr), E);
14840	}
14841	const CharUnits &LHSOffset = LHSValue.getLValueOffset();
14842	const CharUnits &RHSOffset = RHSValue.getLValueOffset();
14843
14844	SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
14845	SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
14846
14847	// C++11 [expr.add]p6:
14848	// Unless both pointers point to elements of the same array object, or
14849	// one past the last element of the array object, the behavior is
14850	// undefined.
14851	if (!LHSDesignator.Invalid && !RHSDesignator.Invalid &&
14852	!AreElementsOfSameArray(getType(LHSValue.Base), LHSDesignator,
14853	RHSDesignator))
14854	Info.CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array);
14855
14856	QualType Type = E->getLHS()->getType();
14857	QualType ElementType = Type->castAs<PointerType>()->getPointeeType();
14858
14859	CharUnits ElementSize;
14860	if (!HandleSizeof(Info, Loc: E->getExprLoc(), Type: ElementType, Size&: ElementSize))
14861	return false;
14862
14863	// As an extension, a type may have zero size (empty struct or union in
14864	// C, array of zero length). Pointer subtraction in such cases has
14865	// undefined behavior, so is not constant.
14866	if (ElementSize.isZero()) {
14867	Info.FFDiag(E, diag::note_constexpr_pointer_subtraction_zero_size)
14868	<< ElementType;
14869	return false;
14870	}
14871
14872	// FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime,
14873	// and produce incorrect results when it overflows. Such behavior
14874	// appears to be non-conforming, but is common, so perhaps we should
14875	// assume the standard intended for such cases to be undefined behavior
14876	// and check for them.
14877
14878	// Compute (LHSOffset - RHSOffset) / Size carefully, checking for
14879	// overflow in the final conversion to ptrdiff_t.
14880	APSInt LHS(llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false);
14881	APSInt RHS(llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false);
14882	APSInt ElemSize(llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true),
14883	false);
14884	APSInt TrueResult = (LHS - RHS) / ElemSize;
14885	APSInt Result = TrueResult.trunc(width: Info.Ctx.getIntWidth(T: E->getType()));
14886
14887	if (Result.extend(width: 65) != TrueResult &&
14888	!HandleOverflow(Info, E, TrueResult, E->getType()))
14889	return false;
14890	return Success(Result, E);
14891	}
14892
14893	return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
14894	}
14895
14896	/// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with
14897	/// a result as the expression's type.
14898	bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr(
14899	const UnaryExprOrTypeTraitExpr *E) {
14900	switch(E->getKind()) {
14901	case UETT_PreferredAlignOf:
14902	case UETT_AlignOf: {
14903	if (E->isArgumentType())
14904	return Success(
14905	GetAlignOfType(Ctx: Info.Ctx, T: E->getArgumentType(), ExprKind: E->getKind()), E);
14906	else
14907	return Success(
14908	GetAlignOfExpr(Ctx: Info.Ctx, E: E->getArgumentExpr(), ExprKind: E->getKind()), E);
14909	}
14910
14911	case UETT_PtrAuthTypeDiscriminator: {
14912	if (E->getArgumentType()->isDependentType())
14913	return false;
14914	return Success(
14915	Info.Ctx.getPointerAuthTypeDiscriminator(T: E->getArgumentType()), E);
14916	}
14917	case UETT_VecStep: {
14918	QualType Ty = E->getTypeOfArgument();
14919
14920	if (Ty->isVectorType()) {
14921	unsigned n = Ty->castAs<VectorType>()->getNumElements();
14922
14923	// The vec_step built-in functions that take a 3-component
14924	// vector return 4. (OpenCL 1.1 spec 6.11.12)
14925	if (n == 3)
14926	n = 4;
14927
14928	return Success(n, E);
14929	} else
14930	return Success(1, E);
14931	}
14932
14933	case UETT_DataSizeOf:
14934	case UETT_SizeOf: {
14935	QualType SrcTy = E->getTypeOfArgument();
14936	// C++ [expr.sizeof]p2: "When applied to a reference or a reference type,
14937	// the result is the size of the referenced type."
14938	if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>())
14939	SrcTy = Ref->getPointeeType();
14940
14941	CharUnits Sizeof;
14942	if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof,
14943	E->getKind() == UETT_DataSizeOf ? SizeOfType::DataSizeOf
14944	: SizeOfType::SizeOf)) {
14945	return false;
14946	}
14947	return Success(Sizeof, E);
14948	}
14949	case UETT_OpenMPRequiredSimdAlign:
14950	assert(E->isArgumentType());
14951	return Success(
14952	Info.Ctx.toCharUnitsFromBits(
14953	BitSize: Info.Ctx.getOpenMPDefaultSimdAlign(T: E->getArgumentType()))
14954	.getQuantity(),
14955	E);
14956	case UETT_VectorElements: {
14957	QualType Ty = E->getTypeOfArgument();
14958	// If the vector has a fixed size, we can determine the number of elements
14959	// at compile time.
14960	if (const auto *VT = Ty->getAs<VectorType>())
14961	return Success(VT->getNumElements(), E);
14962
14963	assert(Ty->isSizelessVectorType());
14964	if (Info.InConstantContext)
14965	Info.CCEDiag(E, diag::note_constexpr_non_const_vectorelements)
14966	<< E->getSourceRange();
14967
14968	return false;
14969	}
14970	case UETT_CountOf: {
14971	QualType Ty = E->getTypeOfArgument();
14972	assert(Ty->isArrayType());
14973
14974	// We don't need to worry about array element qualifiers, so getting the
14975	// unsafe array type is fine.
14976	if (const auto *CAT =
14977	dyn_cast<ConstantArrayType>(Ty->getAsArrayTypeUnsafe())) {
14978	return Success(CAT->getSize(), E);
14979	}
14980
14981	assert(!Ty->isConstantSizeType());
14982
14983	// If it's a variable-length array type, we need to check whether it is a
14984	// multidimensional array. If so, we need to check the size expression of
14985	// the VLA to see if it's a constant size. If so, we can return that value.
14986	const auto *VAT = Info.Ctx.getAsVariableArrayType(T: Ty);
14987	assert(VAT);
14988	if (VAT->getElementType()->isArrayType()) {
14989	std::optional<APSInt> Res =
14990	VAT->getSizeExpr()->getIntegerConstantExpr(Ctx: Info.Ctx);
14991	if (Res) {
14992	// The resulting value always has type size_t, so we need to make the
14993	// returned APInt have the correct sign and bit-width.
14994	APInt Val{
14995	static_cast<unsigned>(Info.Ctx.getTypeSize(T: Info.Ctx.getSizeType())),
14996	Res->getZExtValue()};
14997	return Success(Val, E);
14998	}
14999	}
15000
15001	// Definitely a variable-length type, which is not an ICE.
15002	// FIXME: Better diagnostic.
15003	Info.FFDiag(Loc: E->getBeginLoc());
15004	return false;
15005	}
15006	}
15007
15008	llvm_unreachable("unknown expr/type trait");
15009	}
15010
15011	bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) {
15012	CharUnits Result;
15013	unsigned n = OOE->getNumComponents();
15014	if (n == 0)
15015	return Error(OOE);
15016	QualType CurrentType = OOE->getTypeSourceInfo()->getType();
15017	for (unsigned i = 0; i != n; ++i) {
15018	OffsetOfNode ON = OOE->getComponent(Idx: i);
15019	switch (ON.getKind()) {
15020	case OffsetOfNode::Array: {
15021	const Expr *Idx = OOE->getIndexExpr(Idx: ON.getArrayExprIndex());
15022	APSInt IdxResult;
15023	if (!EvaluateInteger(E: Idx, Result&: IdxResult, Info))
15024	return false;
15025	const ArrayType *AT = Info.Ctx.getAsArrayType(T: CurrentType);
15026	if (!AT)
15027	return Error(OOE);
15028	CurrentType = AT->getElementType();
15029	CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(T: CurrentType);
15030	Result += IdxResult.getSExtValue() * ElementSize;
15031	break;
15032	}
15033
15034	case OffsetOfNode::Field: {
15035	FieldDecl *MemberDecl = ON.getField();
15036	const RecordType *RT = CurrentType->getAs<RecordType>();
15037	if (!RT)
15038	return Error(OOE);
15039	RecordDecl *RD = RT->getDecl();
15040	if (RD->isInvalidDecl()) return false;
15041	const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(D: RD);
15042	unsigned i = MemberDecl->getFieldIndex();
15043	assert(i < RL.getFieldCount() && "offsetof field in wrong type");
15044	Result += Info.Ctx.toCharUnitsFromBits(BitSize: RL.getFieldOffset(FieldNo: i));
15045	CurrentType = MemberDecl->getType().getNonReferenceType();
15046	break;
15047	}
15048
15049	case OffsetOfNode::Identifier:
15050	llvm_unreachable("dependent __builtin_offsetof");
15051
15052	case OffsetOfNode::Base: {
15053	CXXBaseSpecifier *BaseSpec = ON.getBase();
15054	if (BaseSpec->isVirtual())
15055	return Error(OOE);
15056
15057	// Find the layout of the class whose base we are looking into.
15058	const RecordType *RT = CurrentType->getAs<RecordType>();
15059	if (!RT)
15060	return Error(OOE);
15061	RecordDecl *RD = RT->getDecl();
15062	if (RD->isInvalidDecl()) return false;
15063	const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(D: RD);
15064
15065	// Find the base class itself.
15066	CurrentType = BaseSpec->getType();
15067	const RecordType *BaseRT = CurrentType->getAs<RecordType>();
15068	if (!BaseRT)
15069	return Error(OOE);
15070
15071	// Add the offset to the base.
15072	Result += RL.getBaseClassOffset(Base: cast<CXXRecordDecl>(Val: BaseRT->getDecl()));
15073	break;
15074	}
15075	}
15076	}
15077	return Success(Result, OOE);
15078	}
15079
15080	bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
15081	switch (E->getOpcode()) {
15082	default:
15083	// Address, indirect, pre/post inc/dec, etc are not valid constant exprs.
15084	// See C99 6.6p3.
15085	return Error(E);
15086	case UO_Extension:
15087	// FIXME: Should extension allow i-c-e extension expressions in its scope?
15088	// If so, we could clear the diagnostic ID.
15089	return Visit(E->getSubExpr());
15090	case UO_Plus:
15091	// The result is just the value.
15092	return Visit(E->getSubExpr());
15093	case UO_Minus: {
15094	if (!Visit(E->getSubExpr()))
15095	return false;
15096	if (!Result.isInt()) return Error(E);
15097	const APSInt &Value = Result.getInt();
15098	if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow()) {
15099	if (Info.checkingForUndefinedBehavior())
15100	Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
15101	diag::warn_integer_constant_overflow)
15102	<< toString(Value, 10, Value.isSigned(), /*formatAsCLiteral=*/false,
15103	/*UpperCase=*/true, /*InsertSeparators=*/true)
15104	<< E->getType() << E->getSourceRange();
15105
15106	if (!HandleOverflow(Info, E, -Value.extend(width: Value.getBitWidth() + 1),
15107	E->getType()))
15108	return false;
15109	}
15110	return Success(-Value, E);
15111	}
15112	case UO_Not: {
15113	if (!Visit(E->getSubExpr()))
15114	return false;
15115	if (!Result.isInt()) return Error(E);
15116	return Success(~Result.getInt(), E);
15117	}
15118	case UO_LNot: {
15119	bool bres;
15120	if (!EvaluateAsBooleanCondition(E: E->getSubExpr(), Result&: bres, Info))
15121	return false;
15122	return Success(!bres, E);
15123	}
15124	}
15125	}
15126
15127	/// HandleCast - This is used to evaluate implicit or explicit casts where the
15128	/// result type is integer.
15129	bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
15130	const Expr *SubExpr = E->getSubExpr();
15131	QualType DestType = E->getType();
15132	QualType SrcType = SubExpr->getType();
15133
15134	switch (E->getCastKind()) {
15135	case CK_BaseToDerived:
15136	case CK_DerivedToBase:
15137	case CK_UncheckedDerivedToBase:
15138	case CK_Dynamic:
15139	case CK_ToUnion:
15140	case CK_ArrayToPointerDecay:
15141	case CK_FunctionToPointerDecay:
15142	case CK_NullToPointer:
15143	case CK_NullToMemberPointer:
15144	case CK_BaseToDerivedMemberPointer:
15145	case CK_DerivedToBaseMemberPointer:
15146	case CK_ReinterpretMemberPointer:
15147	case CK_ConstructorConversion:
15148	case CK_IntegralToPointer:
15149	case CK_ToVoid:
15150	case CK_VectorSplat:
15151	case CK_IntegralToFloating:
15152	case CK_FloatingCast:
15153	case CK_CPointerToObjCPointerCast:
15154	case CK_BlockPointerToObjCPointerCast:
15155	case CK_AnyPointerToBlockPointerCast:
15156	case CK_ObjCObjectLValueCast:
15157	case CK_FloatingRealToComplex:
15158	case CK_FloatingComplexToReal:
15159	case CK_FloatingComplexCast:
15160	case CK_FloatingComplexToIntegralComplex:
15161	case CK_IntegralRealToComplex:
15162	case CK_IntegralComplexCast:
15163	case CK_IntegralComplexToFloatingComplex:
15164	case CK_BuiltinFnToFnPtr:
15165	case CK_ZeroToOCLOpaqueType:
15166	case CK_NonAtomicToAtomic:
15167	case CK_AddressSpaceConversion:
15168	case CK_IntToOCLSampler:
15169	case CK_FloatingToFixedPoint:
15170	case CK_FixedPointToFloating:
15171	case CK_FixedPointCast:
15172	case CK_IntegralToFixedPoint:
15173	case CK_MatrixCast:
15174	case CK_HLSLAggregateSplatCast:
15175	llvm_unreachable("invalid cast kind for integral value");
15176
15177	case CK_BitCast:
15178	case CK_Dependent:
15179	case CK_LValueBitCast:
15180	case CK_ARCProduceObject:
15181	case CK_ARCConsumeObject:
15182	case CK_ARCReclaimReturnedObject:
15183	case CK_ARCExtendBlockObject:
15184	case CK_CopyAndAutoreleaseBlockObject:
15185	return Error(E);
15186
15187	case CK_UserDefinedConversion:
15188	case CK_LValueToRValue:
15189	case CK_AtomicToNonAtomic:
15190	case CK_NoOp:
15191	case CK_LValueToRValueBitCast:
15192	case CK_HLSLArrayRValue:
15193	case CK_HLSLElementwiseCast:
15194	return ExprEvaluatorBaseTy::VisitCastExpr(E);
15195
15196	case CK_MemberPointerToBoolean:
15197	case CK_PointerToBoolean:
15198	case CK_IntegralToBoolean:
15199	case CK_FloatingToBoolean:
15200	case CK_BooleanToSignedIntegral:
15201	case CK_FloatingComplexToBoolean:
15202	case CK_IntegralComplexToBoolean: {
15203	bool BoolResult;
15204	if (!EvaluateAsBooleanCondition(E: SubExpr, Result&: BoolResult, Info))
15205	return false;
15206	uint64_t IntResult = BoolResult;
15207	if (BoolResult && E->getCastKind() == CK_BooleanToSignedIntegral)
15208	IntResult = (uint64_t)-1;
15209	return Success(IntResult, E);
15210	}
15211
15212	case CK_FixedPointToIntegral: {
15213	APFixedPoint Src(Info.Ctx.getFixedPointSemantics(Ty: SrcType));
15214	if (!EvaluateFixedPoint(E: SubExpr, Result&: Src, Info))
15215	return false;
15216	bool Overflowed;
15217	llvm::APSInt Result = Src.convertToInt(
15218	DstWidth: Info.Ctx.getIntWidth(T: DestType),
15219	DstSign: DestType->isSignedIntegerOrEnumerationType(), Overflow: &Overflowed);
15220	if (Overflowed && !HandleOverflow(Info, E, Result, DestType))
15221	return false;
15222	return Success(Result, E);
15223	}
15224
15225	case CK_FixedPointToBoolean: {
15226	// Unsigned padding does not affect this.
15227	APValue Val;
15228	if (!Evaluate(Result&: Val, Info, E: SubExpr))
15229	return false;
15230	return Success(Val.getFixedPoint().getBoolValue(), E);
15231	}
15232
15233	case CK_IntegralCast: {
15234	if (!Visit(SubExpr))
15235	return false;
15236
15237	if (!Result.isInt()) {
15238	// Allow casts of address-of-label differences if they are no-ops
15239	// or narrowing. (The narrowing case isn't actually guaranteed to
15240	// be constant-evaluatable except in some narrow cases which are hard
15241	// to detect here. We let it through on the assumption the user knows
15242	// what they are doing.)
15243	if (Result.isAddrLabelDiff())
15244	return Info.Ctx.getTypeSize(T: DestType) <= Info.Ctx.getTypeSize(T: SrcType);
15245	// Only allow casts of lvalues if they are lossless.
15246	return Info.Ctx.getTypeSize(T: DestType) == Info.Ctx.getTypeSize(T: SrcType);
15247	}
15248
15249	if (Info.Ctx.getLangOpts().CPlusPlus && DestType->isEnumeralType()) {
15250	const EnumType *ET = dyn_cast<EnumType>(Val: DestType.getCanonicalType());
15251	const EnumDecl *ED = ET->getDecl();
15252	// Check that the value is within the range of the enumeration values.
15253	//
15254	// This corressponds to [expr.static.cast]p10 which says:
15255	// A value of integral or enumeration type can be explicitly converted
15256	// to a complete enumeration type ... If the enumeration type does not
15257	// have a fixed underlying type, the value is unchanged if the original
15258	// value is within the range of the enumeration values ([dcl.enum]), and
15259	// otherwise, the behavior is undefined.
15260	//
15261	// This was resolved as part of DR2338 which has CD5 status.
15262	if (!ED->isFixed()) {
15263	llvm::APInt Min;
15264	llvm::APInt Max;
15265
15266	ED->getValueRange(Max, Min);
15267	--Max;
15268
15269	if (ED->getNumNegativeBits() &&
15270	(Max.slt(Result.getInt().getSExtValue()) ||
15271	Min.sgt(Result.getInt().getSExtValue())))
15272	Info.CCEDiag(E, diag::note_constexpr_unscoped_enum_out_of_range)
15273	<< llvm::toString(Result.getInt(), 10) << Min.getSExtValue()
15274	<< Max.getSExtValue() << ED;
15275	else if (!ED->getNumNegativeBits() &&
15276	Max.ult(Result.getInt().getZExtValue()))
15277	Info.CCEDiag(E, diag::note_constexpr_unscoped_enum_out_of_range)
15278	<< llvm::toString(Result.getInt(), 10) << Min.getZExtValue()
15279	<< Max.getZExtValue() << ED;
15280	}
15281	}
15282
15283	return Success(HandleIntToIntCast(Info, E, DestType, SrcType,
15284	Result.getInt()), E);
15285	}
15286
15287	case CK_PointerToIntegral: {
15288	CCEDiag(E, diag::note_constexpr_invalid_cast)
15289	<< diag::ConstexprInvalidCastKind::ThisConversionOrReinterpret
15290	<< Info.Ctx.getLangOpts().CPlusPlus << E->getSourceRange();
15291
15292	LValue LV;
15293	if (!EvaluatePointer(E: SubExpr, Result&: LV, Info))
15294	return false;
15295
15296	if (LV.getLValueBase()) {
15297	// Only allow based lvalue casts if they are lossless.
15298	// FIXME: Allow a larger integer size than the pointer size, and allow
15299	// narrowing back down to pointer width in subsequent integral casts.
15300	// FIXME: Check integer type's active bits, not its type size.
15301	if (Info.Ctx.getTypeSize(T: DestType) != Info.Ctx.getTypeSize(T: SrcType))
15302	return Error(E);
15303
15304	LV.Designator.setInvalid();
15305	LV.moveInto(V&: Result);
15306	return true;
15307	}
15308
15309	APSInt AsInt;
15310	APValue V;
15311	LV.moveInto(V);
15312	if (!V.toIntegralConstant(Result&: AsInt, SrcTy: SrcType, Ctx: Info.Ctx))
15313	llvm_unreachable("Can't cast this!");
15314
15315	return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E);
15316	}
15317
15318	case CK_IntegralComplexToReal: {
15319	ComplexValue C;
15320	if (!EvaluateComplex(E: SubExpr, Res&: C, Info))
15321	return false;
15322	return Success(C.getComplexIntReal(), E);
15323	}
15324
15325	case CK_FloatingToIntegral: {
15326	APFloat F(0.0);
15327	if (!EvaluateFloat(E: SubExpr, Result&: F, Info))
15328	return false;
15329
15330	APSInt Value;
15331	if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value))
15332	return false;
15333	return Success(Value, E);
15334	}
15335	case CK_HLSLVectorTruncation: {
15336	APValue Val;
15337	if (!EvaluateVector(E: SubExpr, Result&: Val, Info))
15338	return Error(E);
15339	return Success(Val.getVectorElt(I: 0), E);
15340	}
15341	}
15342
15343	llvm_unreachable("unknown cast resulting in integral value");
15344	}
15345
15346	bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
15347	if (E->getSubExpr()->getType()->isAnyComplexType()) {
15348	ComplexValue LV;
15349	if (!EvaluateComplex(E: E->getSubExpr(), Res&: LV, Info))
15350	return false;
15351	if (!LV.isComplexInt())
15352	return Error(E);
15353	return Success(LV.getComplexIntReal(), E);
15354	}
15355
15356	return Visit(E->getSubExpr());
15357	}
15358
15359	bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
15360	if (E->getSubExpr()->getType()->isComplexIntegerType()) {
15361	ComplexValue LV;
15362	if (!EvaluateComplex(E: E->getSubExpr(), Res&: LV, Info))
15363	return false;
15364	if (!LV.isComplexInt())
15365	return Error(E);
15366	return Success(LV.getComplexIntImag(), E);
15367	}
15368
15369	VisitIgnoredValue(E: E->getSubExpr());
15370	return Success(0, E);
15371	}
15372
15373	bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) {
15374	return Success(E->getPackLength(), E);
15375	}
15376
15377	bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) {
15378	return Success(E->getValue(), E);
15379	}
15380
15381	bool IntExprEvaluator::VisitConceptSpecializationExpr(
15382	const ConceptSpecializationExpr *E) {
15383	return Success(E->isSatisfied(), E);
15384	}
15385
15386	bool IntExprEvaluator::VisitRequiresExpr(const RequiresExpr *E) {
15387	return Success(E->isSatisfied(), E);
15388	}
15389
15390	bool FixedPointExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
15391	switch (E->getOpcode()) {
15392	default:
15393	// Invalid unary operators
15394	return Error(E);
15395	case UO_Plus:
15396	// The result is just the value.
15397	return Visit(E->getSubExpr());
15398	case UO_Minus: {
15399	if (!Visit(E->getSubExpr())) return false;
15400	if (!Result.isFixedPoint())
15401	return Error(E);
15402	bool Overflowed;
15403	APFixedPoint Negated = Result.getFixedPoint().negate(Overflow: &Overflowed);
15404	if (Overflowed && !HandleOverflow(Info, E, Negated, E->getType()))
15405	return false;
15406	return Success(Negated, E);
15407	}
15408	case UO_LNot: {
15409	bool bres;
15410	if (!EvaluateAsBooleanCondition(E: E->getSubExpr(), Result&: bres, Info))
15411	return false;
15412	return Success(!bres, E);
15413	}
15414	}
15415	}
15416
15417	bool FixedPointExprEvaluator::VisitCastExpr(const CastExpr *E) {
15418	const Expr *SubExpr = E->getSubExpr();
15419	QualType DestType = E->getType();
15420	assert(DestType->isFixedPointType() &&
15421	"Expected destination type to be a fixed point type");
15422	auto DestFXSema = Info.Ctx.getFixedPointSemantics(Ty: DestType);
15423
15424	switch (E->getCastKind()) {
15425	case CK_FixedPointCast: {
15426	APFixedPoint Src(Info.Ctx.getFixedPointSemantics(Ty: SubExpr->getType()));
15427	if (!EvaluateFixedPoint(E: SubExpr, Result&: Src, Info))
15428	return false;
15429	bool Overflowed;
15430	APFixedPoint Result = Src.convert(DstSema: DestFXSema, Overflow: &Overflowed);
15431	if (Overflowed) {
15432	if (Info.checkingForUndefinedBehavior())
15433	Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
15434	diag::warn_fixedpoint_constant_overflow)
15435	<< Result.toString() << E->getType();
15436	if (!HandleOverflow(Info, E, Result, E->getType()))
15437	return false;
15438	}
15439	return Success(Result, E);
15440	}
15441	case CK_IntegralToFixedPoint: {
15442	APSInt Src;
15443	if (!EvaluateInteger(E: SubExpr, Result&: Src, Info))
15444	return false;
15445
15446	bool Overflowed;
15447	APFixedPoint IntResult = APFixedPoint::getFromIntValue(
15448	Value: Src, DstFXSema: Info.Ctx.getFixedPointSemantics(Ty: DestType), Overflow: &Overflowed);
15449
15450	if (Overflowed) {
15451	if (Info.checkingForUndefinedBehavior())
15452	Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
15453	diag::warn_fixedpoint_constant_overflow)
15454	<< IntResult.toString() << E->getType();
15455	if (!HandleOverflow(Info, E, IntResult, E->getType()))
15456	return false;
15457	}
15458
15459	return Success(IntResult, E);
15460	}
15461	case CK_FloatingToFixedPoint: {
15462	APFloat Src(0.0);
15463	if (!EvaluateFloat(E: SubExpr, Result&: Src, Info))
15464	return false;
15465
15466	bool Overflowed;
15467	APFixedPoint Result = APFixedPoint::getFromFloatValue(
15468	Value: Src, DstFXSema: Info.Ctx.getFixedPointSemantics(Ty: DestType), Overflow: &Overflowed);
15469
15470	if (Overflowed) {
15471	if (Info.checkingForUndefinedBehavior())
15472	Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
15473	diag::warn_fixedpoint_constant_overflow)
15474	<< Result.toString() << E->getType();
15475	if (!HandleOverflow(Info, E, Result, E->getType()))
15476	return false;
15477	}
15478
15479	return Success(Result, E);
15480	}
15481	case CK_NoOp:
15482	case CK_LValueToRValue:
15483	return ExprEvaluatorBaseTy::VisitCastExpr(E);
15484	default:
15485	return Error(E);
15486	}
15487	}
15488
15489	bool FixedPointExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
15490	if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
15491	return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
15492
15493	const Expr *LHS = E->getLHS();
15494	const Expr *RHS = E->getRHS();
15495	FixedPointSemantics ResultFXSema =
15496	Info.Ctx.getFixedPointSemantics(Ty: E->getType());
15497
15498	APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(Ty: LHS->getType()));
15499	if (!EvaluateFixedPointOrInteger(E: LHS, Result&: LHSFX, Info))
15500	return false;
15501	APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(Ty: RHS->getType()));
15502	if (!EvaluateFixedPointOrInteger(E: RHS, Result&: RHSFX, Info))
15503	return false;
15504
15505	bool OpOverflow = false, ConversionOverflow = false;
15506	APFixedPoint Result(LHSFX.getSemantics());
15507	switch (E->getOpcode()) {
15508	case BO_Add: {
15509	Result = LHSFX.add(Other: RHSFX, Overflow: &OpOverflow)
15510	.convert(DstSema: ResultFXSema, Overflow: &ConversionOverflow);
15511	break;
15512	}
15513	case BO_Sub: {
15514	Result = LHSFX.sub(Other: RHSFX, Overflow: &OpOverflow)
15515	.convert(DstSema: ResultFXSema, Overflow: &ConversionOverflow);
15516	break;
15517	}
15518	case BO_Mul: {
15519	Result = LHSFX.mul(Other: RHSFX, Overflow: &OpOverflow)
15520	.convert(DstSema: ResultFXSema, Overflow: &ConversionOverflow);
15521	break;
15522	}
15523	case BO_Div: {
15524	if (RHSFX.getValue() == 0) {
15525	Info.FFDiag(E, diag::note_expr_divide_by_zero);
15526	return false;
15527	}
15528	Result = LHSFX.div(Other: RHSFX, Overflow: &OpOverflow)
15529	.convert(DstSema: ResultFXSema, Overflow: &ConversionOverflow);
15530	break;
15531	}
15532	case BO_Shl:
15533	case BO_Shr: {
15534	FixedPointSemantics LHSSema = LHSFX.getSemantics();
15535	llvm::APSInt RHSVal = RHSFX.getValue();
15536
15537	unsigned ShiftBW =
15538	LHSSema.getWidth() - (unsigned)LHSSema.hasUnsignedPadding();
15539	unsigned Amt = RHSVal.getLimitedValue(Limit: ShiftBW - 1);
15540	// Embedded-C 4.1.6.2.2:
15541	// The right operand must be nonnegative and less than the total number
15542	// of (nonpadding) bits of the fixed-point operand ...
15543	if (RHSVal.isNegative())
15544	Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHSVal;
15545	else if (Amt != RHSVal)
15546	Info.CCEDiag(E, diag::note_constexpr_large_shift)
15547	<< RHSVal << E->getType() << ShiftBW;
15548
15549	if (E->getOpcode() == BO_Shl)
15550	Result = LHSFX.shl(Amt, Overflow: &OpOverflow);
15551	else
15552	Result = LHSFX.shr(Amt, Overflow: &OpOverflow);
15553	break;
15554	}
15555	default:
15556	return false;
15557	}
15558	if (OpOverflow || ConversionOverflow) {
15559	if (Info.checkingForUndefinedBehavior())
15560	Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
15561	diag::warn_fixedpoint_constant_overflow)
15562	<< Result.toString() << E->getType();
15563	if (!HandleOverflow(Info, E, Result, E->getType()))
15564	return false;
15565	}
15566	return Success(Result, E);
15567	}
15568
15569	//===----------------------------------------------------------------------===//
15570	// Float Evaluation
15571	//===----------------------------------------------------------------------===//
15572
15573	namespace {
15574	class FloatExprEvaluator
15575	: public ExprEvaluatorBase<FloatExprEvaluator> {
15576	APFloat &Result;
15577	public:
15578	FloatExprEvaluator(EvalInfo &info, APFloat &result)
15579	: ExprEvaluatorBaseTy(info), Result(result) {}
15580
15581	bool Success(const APValue &V, const Expr *e) {
15582	Result = V.getFloat();
15583	return true;
15584	}
15585
15586	bool ZeroInitialization(const Expr *E) {
15587	Result = APFloat::getZero(Sem: Info.Ctx.getFloatTypeSemantics(T: E->getType()));
15588	return true;
15589	}
15590
15591	bool VisitCallExpr(const CallExpr *E);
15592
15593	bool VisitUnaryOperator(const UnaryOperator *E);
15594	bool VisitBinaryOperator(const BinaryOperator *E);
15595	bool VisitFloatingLiteral(const FloatingLiteral *E);
15596	bool VisitCastExpr(const CastExpr *E);
15597
15598	bool VisitUnaryReal(const UnaryOperator *E);
15599	bool VisitUnaryImag(const UnaryOperator *E);
15600
15601	// FIXME: Missing: array subscript of vector, member of vector
15602	};
15603	} // end anonymous namespace
15604
15605	static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) {
15606	assert(!E->isValueDependent());
15607	assert(E->isPRValue() && E->getType()->isRealFloatingType());
15608	return FloatExprEvaluator(Info, Result).Visit(E);
15609	}
15610
15611	static bool TryEvaluateBuiltinNaN(const ASTContext &Context,
15612	QualType ResultTy,
15613	const Expr *Arg,
15614	bool SNaN,
15615	llvm::APFloat &Result) {
15616	const StringLiteral *S = dyn_cast<StringLiteral>(Val: Arg->IgnoreParenCasts());
15617	if (!S) return false;
15618
15619	const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(T: ResultTy);
15620
15621	llvm::APInt fill;
15622
15623	// Treat empty strings as if they were zero.
15624	if (S->getString().empty())
15625	fill = llvm::APInt(32, 0);
15626	else if (S->getString().getAsInteger(Radix: 0, Result&: fill))
15627	return false;
15628
15629	if (Context.getTargetInfo().isNan2008()) {
15630	if (SNaN)
15631	Result = llvm::APFloat::getSNaN(Sem, Negative: false, payload: &fill);
15632	else
15633	Result = llvm::APFloat::getQNaN(Sem, Negative: false, payload: &fill);
15634	} else {
15635	// Prior to IEEE 754-2008, architectures were allowed to choose whether
15636	// the first bit of their significand was set for qNaN or sNaN. MIPS chose
15637	// a different encoding to what became a standard in 2008, and for pre-
15638	// 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as
15639	// sNaN. This is now known as "legacy NaN" encoding.
15640	if (SNaN)
15641	Result = llvm::APFloat::getQNaN(Sem, Negative: false, payload: &fill);
15642	else
15643	Result = llvm::APFloat::getSNaN(Sem, Negative: false, payload: &fill);
15644	}
15645
15646	return true;
15647	}
15648
15649	bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
15650	if (!IsConstantEvaluatedBuiltinCall(E))
15651	return ExprEvaluatorBaseTy::VisitCallExpr(E);
15652
15653	switch (E->getBuiltinCallee()) {
15654	default:
15655	return false;
15656
15657	case Builtin::BI__builtin_huge_val:
15658	case Builtin::BI__builtin_huge_valf:
15659	case Builtin::BI__builtin_huge_vall:
15660	case Builtin::BI__builtin_huge_valf16:
15661	case Builtin::BI__builtin_huge_valf128:
15662	case Builtin::BI__builtin_inf:
15663	case Builtin::BI__builtin_inff:
15664	case Builtin::BI__builtin_infl:
15665	case Builtin::BI__builtin_inff16:
15666	case Builtin::BI__builtin_inff128: {
15667	const llvm::fltSemantics &Sem =
15668	Info.Ctx.getFloatTypeSemantics(T: E->getType());
15669	Result = llvm::APFloat::getInf(Sem);
15670	return true;
15671	}
15672
15673	case Builtin::BI__builtin_nans:
15674	case Builtin::BI__builtin_nansf:
15675	case Builtin::BI__builtin_nansl:
15676	case Builtin::BI__builtin_nansf16:
15677	case Builtin::BI__builtin_nansf128:
15678	if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(Arg: 0),
15679	true, Result))
15680	return Error(E);
15681	return true;
15682
15683	case Builtin::BI__builtin_nan:
15684	case Builtin::BI__builtin_nanf:
15685	case Builtin::BI__builtin_nanl:
15686	case Builtin::BI__builtin_nanf16:
15687	case Builtin::BI__builtin_nanf128:
15688	// If this is __builtin_nan() turn this into a nan, otherwise we
15689	// can't constant fold it.
15690	if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(Arg: 0),
15691	false, Result))
15692	return Error(E);
15693	return true;
15694
15695	case Builtin::BI__builtin_fabs:
15696	case Builtin::BI__builtin_fabsf:
15697	case Builtin::BI__builtin_fabsl:
15698	case Builtin::BI__builtin_fabsf128:
15699	// The C standard says "fabs raises no floating-point exceptions,
15700	// even if x is a signaling NaN. The returned value is independent of
15701	// the current rounding direction mode." Therefore constant folding can
15702	// proceed without regard to the floating point settings.
15703	// Reference, WG14 N2478 F.10.4.3
15704	if (!EvaluateFloat(E: E->getArg(Arg: 0), Result, Info))
15705	return false;
15706
15707	if (Result.isNegative())
15708	Result.changeSign();
15709	return true;
15710
15711	case Builtin::BI__arithmetic_fence:
15712	return EvaluateFloat(E: E->getArg(Arg: 0), Result, Info);
15713
15714	// FIXME: Builtin::BI__builtin_powi
15715	// FIXME: Builtin::BI__builtin_powif
15716	// FIXME: Builtin::BI__builtin_powil
15717
15718	case Builtin::BI__builtin_copysign:
15719	case Builtin::BI__builtin_copysignf:
15720	case Builtin::BI__builtin_copysignl:
15721	case Builtin::BI__builtin_copysignf128: {
15722	APFloat RHS(0.);
15723	if (!EvaluateFloat(E: E->getArg(Arg: 0), Result, Info) ||
15724	!EvaluateFloat(E: E->getArg(Arg: 1), Result&: RHS, Info))
15725	return false;
15726	Result.copySign(RHS);
15727	return true;
15728	}
15729
15730	case Builtin::BI__builtin_fmax:
15731	case Builtin::BI__builtin_fmaxf:
15732	case Builtin::BI__builtin_fmaxl:
15733	case Builtin::BI__builtin_fmaxf16:
15734	case Builtin::BI__builtin_fmaxf128: {
15735	APFloat RHS(0.);
15736	if (!EvaluateFloat(E: E->getArg(Arg: 0), Result, Info) ||
15737	!EvaluateFloat(E: E->getArg(Arg: 1), Result&: RHS, Info))
15738	return false;
15739	Result = maxnum(A: Result, B: RHS);
15740	return true;
15741	}
15742
15743	case Builtin::BI__builtin_fmin:
15744	case Builtin::BI__builtin_fminf:
15745	case Builtin::BI__builtin_fminl:
15746	case Builtin::BI__builtin_fminf16:
15747	case Builtin::BI__builtin_fminf128: {
15748	APFloat RHS(0.);
15749	if (!EvaluateFloat(E: E->getArg(Arg: 0), Result, Info) ||
15750	!EvaluateFloat(E: E->getArg(Arg: 1), Result&: RHS, Info))
15751	return false;
15752	Result = minnum(A: Result, B: RHS);
15753	return true;
15754	}
15755
15756	case Builtin::BI__builtin_fmaximum_num:
15757	case Builtin::BI__builtin_fmaximum_numf:
15758	case Builtin::BI__builtin_fmaximum_numl:
15759	case Builtin::BI__builtin_fmaximum_numf16:
15760	case Builtin::BI__builtin_fmaximum_numf128: {
15761	APFloat RHS(0.);
15762	if (!EvaluateFloat(E: E->getArg(Arg: 0), Result, Info) ||
15763	!EvaluateFloat(E: E->getArg(Arg: 1), Result&: RHS, Info))
15764	return false;
15765	Result = maximumnum(A: Result, B: RHS);
15766	return true;
15767	}
15768
15769	case Builtin::BI__builtin_fminimum_num:
15770	case Builtin::BI__builtin_fminimum_numf:
15771	case Builtin::BI__builtin_fminimum_numl:
15772	case Builtin::BI__builtin_fminimum_numf16:
15773	case Builtin::BI__builtin_fminimum_numf128: {
15774	APFloat RHS(0.);
15775	if (!EvaluateFloat(E: E->getArg(Arg: 0), Result, Info) ||
15776	!EvaluateFloat(E: E->getArg(Arg: 1), Result&: RHS, Info))
15777	return false;
15778	Result = minimumnum(A: Result, B: RHS);
15779	return true;
15780	}
15781	}
15782	}
15783
15784	bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
15785	if (E->getSubExpr()->getType()->isAnyComplexType()) {
15786	ComplexValue CV;
15787	if (!EvaluateComplex(E: E->getSubExpr(), Res&: CV, Info))
15788	return false;
15789	Result = CV.FloatReal;
15790	return true;
15791	}
15792
15793	return Visit(E->getSubExpr());
15794	}
15795
15796	bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
15797	if (E->getSubExpr()->getType()->isAnyComplexType()) {
15798	ComplexValue CV;
15799	if (!EvaluateComplex(E: E->getSubExpr(), Res&: CV, Info))
15800	return false;
15801	Result = CV.FloatImag;
15802	return true;
15803	}
15804
15805	VisitIgnoredValue(E: E->getSubExpr());
15806	const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(T: E->getType());
15807	Result = llvm::APFloat::getZero(Sem);
15808	return true;
15809	}
15810
15811	bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
15812	switch (E->getOpcode()) {
15813	default: return Error(E);
15814	case UO_Plus:
15815	return EvaluateFloat(E: E->getSubExpr(), Result, Info);
15816	case UO_Minus:
15817	// In C standard, WG14 N2478 F.3 p4
15818	// "the unary - raises no floating point exceptions,
15819	// even if the operand is signalling."
15820	if (!EvaluateFloat(E: E->getSubExpr(), Result, Info))
15821	return false;
15822	Result.changeSign();
15823	return true;
15824	}
15825	}
15826
15827	bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
15828	if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
15829	return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
15830
15831	APFloat RHS(0.0);
15832	bool LHSOK = EvaluateFloat(E: E->getLHS(), Result, Info);
15833	if (!LHSOK && !Info.noteFailure())
15834	return false;
15835	return EvaluateFloat(E: E->getRHS(), Result&: RHS, Info) && LHSOK &&
15836	handleFloatFloatBinOp(Info, E, LHS&: Result, Opcode: E->getOpcode(), RHS);
15837	}
15838
15839	bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) {
15840	Result = E->getValue();
15841	return true;
15842	}
15843
15844	bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) {
15845	const Expr* SubExpr = E->getSubExpr();
15846
15847	switch (E->getCastKind()) {
15848	default:
15849	return ExprEvaluatorBaseTy::VisitCastExpr(E);
15850
15851	case CK_IntegralToFloating: {
15852	APSInt IntResult;
15853	const FPOptions FPO = E->getFPFeaturesInEffect(
15854	LO: Info.Ctx.getLangOpts());
15855	return EvaluateInteger(E: SubExpr, Result&: IntResult, Info) &&
15856	HandleIntToFloatCast(Info, E, FPO, SubExpr->getType(),
15857	IntResult, E->getType(), Result);
15858	}
15859
15860	case CK_FixedPointToFloating: {
15861	APFixedPoint FixResult(Info.Ctx.getFixedPointSemantics(Ty: SubExpr->getType()));
15862	if (!EvaluateFixedPoint(E: SubExpr, Result&: FixResult, Info))
15863	return false;
15864	Result =
15865	FixResult.convertToFloat(FloatSema: Info.Ctx.getFloatTypeSemantics(T: E->getType()));
15866	return true;
15867	}
15868
15869	case CK_FloatingCast: {
15870	if (!Visit(SubExpr))
15871	return false;
15872	return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(),
15873	Result);
15874	}
15875
15876	case CK_FloatingComplexToReal: {
15877	ComplexValue V;
15878	if (!EvaluateComplex(E: SubExpr, Res&: V, Info))
15879	return false;
15880	Result = V.getComplexFloatReal();
15881	return true;
15882	}
15883	case CK_HLSLVectorTruncation: {
15884	APValue Val;
15885	if (!EvaluateVector(E: SubExpr, Result&: Val, Info))
15886	return Error(E);
15887	return Success(Val.getVectorElt(I: 0), E);
15888	}
15889	}
15890	}
15891
15892	//===----------------------------------------------------------------------===//
15893	// Complex Evaluation (for float and integer)
15894	//===----------------------------------------------------------------------===//
15895
15896	namespace {
15897	class ComplexExprEvaluator
15898	: public ExprEvaluatorBase<ComplexExprEvaluator> {
15899	ComplexValue &Result;
15900
15901	public:
15902	ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result)
15903	: ExprEvaluatorBaseTy(info), Result(Result) {}
15904
15905	bool Success(const APValue &V, const Expr *e) {
15906	Result.setFrom(V);
15907	return true;
15908	}
15909
15910	bool ZeroInitialization(const Expr *E);
15911
15912	//===--------------------------------------------------------------------===//
15913	// Visitor Methods
15914	//===--------------------------------------------------------------------===//
15915
15916	bool VisitImaginaryLiteral(const ImaginaryLiteral *E);
15917	bool VisitCastExpr(const CastExpr *E);
15918	bool VisitBinaryOperator(const BinaryOperator *E);
15919	bool VisitUnaryOperator(const UnaryOperator *E);
15920	bool VisitInitListExpr(const InitListExpr *E);
15921	bool VisitCallExpr(const CallExpr *E);
15922	};
15923	} // end anonymous namespace
15924
15925	static bool EvaluateComplex(const Expr *E, ComplexValue &Result,
15926	EvalInfo &Info) {
15927	assert(!E->isValueDependent());
15928	assert(E->isPRValue() && E->getType()->isAnyComplexType());
15929	return ComplexExprEvaluator(Info, Result).Visit(E);
15930	}
15931
15932	bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) {
15933	QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType();
15934	if (ElemTy->isRealFloatingType()) {
15935	Result.makeComplexFloat();
15936	APFloat Zero = APFloat::getZero(Sem: Info.Ctx.getFloatTypeSemantics(T: ElemTy));
15937	Result.FloatReal = Zero;
15938	Result.FloatImag = Zero;
15939	} else {
15940	Result.makeComplexInt();
15941	APSInt Zero = Info.Ctx.MakeIntValue(Value: 0, Type: ElemTy);
15942	Result.IntReal = Zero;
15943	Result.IntImag = Zero;
15944	}
15945	return true;
15946	}
15947
15948	bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) {
15949	const Expr* SubExpr = E->getSubExpr();
15950
15951	if (SubExpr->getType()->isRealFloatingType()) {
15952	Result.makeComplexFloat();
15953	APFloat &Imag = Result.FloatImag;
15954	if (!EvaluateFloat(E: SubExpr, Result&: Imag, Info))
15955	return false;
15956
15957	Result.FloatReal = APFloat(Imag.getSemantics());
15958	return true;
15959	} else {
15960	assert(SubExpr->getType()->isIntegerType() &&
15961	"Unexpected imaginary literal.");
15962
15963	Result.makeComplexInt();
15964	APSInt &Imag = Result.IntImag;
15965	if (!EvaluateInteger(E: SubExpr, Result&: Imag, Info))
15966	return false;
15967
15968	Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned());
15969	return true;
15970	}
15971	}
15972
15973	bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
15974
15975	switch (E->getCastKind()) {
15976	case CK_BitCast:
15977	case CK_BaseToDerived:
15978	case CK_DerivedToBase:
15979	case CK_UncheckedDerivedToBase:
15980	case CK_Dynamic:
15981	case CK_ToUnion:
15982	case CK_ArrayToPointerDecay:
15983	case CK_FunctionToPointerDecay:
15984	case CK_NullToPointer:
15985	case CK_NullToMemberPointer:
15986	case CK_BaseToDerivedMemberPointer:
15987	case CK_DerivedToBaseMemberPointer:
15988	case CK_MemberPointerToBoolean:
15989	case CK_ReinterpretMemberPointer:
15990	case CK_ConstructorConversion:
15991	case CK_IntegralToPointer:
15992	case CK_PointerToIntegral:
15993	case CK_PointerToBoolean:
15994	case CK_ToVoid:
15995	case CK_VectorSplat:
15996	case CK_IntegralCast:
15997	case CK_BooleanToSignedIntegral:
15998	case CK_IntegralToBoolean:
15999	case CK_IntegralToFloating:
16000	case CK_FloatingToIntegral:
16001	case CK_FloatingToBoolean:
16002	case CK_FloatingCast:
16003	case CK_CPointerToObjCPointerCast:
16004	case CK_BlockPointerToObjCPointerCast:
16005	case CK_AnyPointerToBlockPointerCast:
16006	case CK_ObjCObjectLValueCast:
16007	case CK_FloatingComplexToReal:
16008	case CK_FloatingComplexToBoolean:
16009	case CK_IntegralComplexToReal:
16010	case CK_IntegralComplexToBoolean:
16011	case CK_ARCProduceObject:
16012	case CK_ARCConsumeObject:
16013	case CK_ARCReclaimReturnedObject:
16014	case CK_ARCExtendBlockObject:
16015	case CK_CopyAndAutoreleaseBlockObject:
16016	case CK_BuiltinFnToFnPtr:
16017	case CK_ZeroToOCLOpaqueType:
16018	case CK_NonAtomicToAtomic:
16019	case CK_AddressSpaceConversion:
16020	case CK_IntToOCLSampler:
16021	case CK_FloatingToFixedPoint:
16022	case CK_FixedPointToFloating:
16023	case CK_FixedPointCast:
16024	case CK_FixedPointToBoolean:
16025	case CK_FixedPointToIntegral:
16026	case CK_IntegralToFixedPoint:
16027	case CK_MatrixCast:
16028	case CK_HLSLVectorTruncation:
16029	case CK_HLSLElementwiseCast:
16030	case CK_HLSLAggregateSplatCast:
16031	llvm_unreachable("invalid cast kind for complex value");
16032
16033	case CK_LValueToRValue:
16034	case CK_AtomicToNonAtomic:
16035	case CK_NoOp:
16036	case CK_LValueToRValueBitCast:
16037	case CK_HLSLArrayRValue:
16038	return ExprEvaluatorBaseTy::VisitCastExpr(E);
16039
16040	case CK_Dependent:
16041	case CK_LValueBitCast:
16042	case CK_UserDefinedConversion:
16043	return Error(E);
16044
16045	case CK_FloatingRealToComplex: {
16046	APFloat &Real = Result.FloatReal;
16047	if (!EvaluateFloat(E: E->getSubExpr(), Result&: Real, Info))
16048	return false;
16049
16050	Result.makeComplexFloat();
16051	Result.FloatImag = APFloat(Real.getSemantics());
16052	return true;
16053	}
16054
16055	case CK_FloatingComplexCast: {
16056	if (!Visit(E->getSubExpr()))
16057	return false;
16058
16059	QualType To = E->getType()->castAs<ComplexType>()->getElementType();
16060	QualType From
16061	= E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
16062
16063	return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) &&
16064	HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag);
16065	}
16066
16067	case CK_FloatingComplexToIntegralComplex: {
16068	if (!Visit(E->getSubExpr()))
16069	return false;
16070
16071	QualType To = E->getType()->castAs<ComplexType>()->getElementType();
16072	QualType From
16073	= E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
16074	Result.makeComplexInt();
16075	return HandleFloatToIntCast(Info, E, From, Result.FloatReal,
16076	To, Result.IntReal) &&
16077	HandleFloatToIntCast(Info, E, From, Result.FloatImag,
16078	To, Result.IntImag);
16079	}
16080
16081	case CK_IntegralRealToComplex: {
16082	APSInt &Real = Result.IntReal;
16083	if (!EvaluateInteger(E: E->getSubExpr(), Result&: Real, Info))
16084	return false;
16085
16086	Result.makeComplexInt();
16087	Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned());
16088	return true;
16089	}
16090
16091	case CK_IntegralComplexCast: {
16092	if (!Visit(E->getSubExpr()))
16093	return false;
16094
16095	QualType To = E->getType()->castAs<ComplexType>()->getElementType();
16096	QualType From
16097	= E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
16098
16099	Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal);
16100	Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag);
16101	return true;
16102	}
16103
16104	case CK_IntegralComplexToFloatingComplex: {
16105	if (!Visit(E->getSubExpr()))
16106	return false;
16107
16108	const FPOptions FPO = E->getFPFeaturesInEffect(
16109	LO: Info.Ctx.getLangOpts());
16110	QualType To = E->getType()->castAs<ComplexType>()->getElementType();
16111	QualType From
16112	= E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
16113	Result.makeComplexFloat();
16114	return HandleIntToFloatCast(Info, E, FPO, From, Result.IntReal,
16115	To, Result.FloatReal) &&
16116	HandleIntToFloatCast(Info, E, FPO, From, Result.IntImag,
16117	To, Result.FloatImag);
16118	}
16119	}
16120
16121	llvm_unreachable("unknown cast resulting in complex value");
16122	}
16123
16124	void HandleComplexComplexMul(APFloat A, APFloat B, APFloat C, APFloat D,
16125	APFloat &ResR, APFloat &ResI) {
16126	// This is an implementation of complex multiplication according to the
16127	// constraints laid out in C11 Annex G. The implementation uses the
16128	// following naming scheme:
16129	// (a + ib) * (c + id)
16130
16131	APFloat AC = A * C;
16132	APFloat BD = B * D;
16133	APFloat AD = A * D;
16134	APFloat BC = B * C;
16135	ResR = AC - BD;
16136	ResI = AD + BC;
16137	if (ResR.isNaN() && ResI.isNaN()) {
16138	bool Recalc = false;
16139	if (A.isInfinity() || B.isInfinity()) {
16140	A = APFloat::copySign(Value: APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0),
16141	Sign: A);
16142	B = APFloat::copySign(Value: APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0),
16143	Sign: B);
16144	if (C.isNaN())
16145	C = APFloat::copySign(Value: APFloat(C.getSemantics()), Sign: C);
16146	if (D.isNaN())
16147	D = APFloat::copySign(Value: APFloat(D.getSemantics()), Sign: D);
16148	Recalc = true;
16149	}
16150	if (C.isInfinity() || D.isInfinity()) {
16151	C = APFloat::copySign(Value: APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0),
16152	Sign: C);
16153	D = APFloat::copySign(Value: APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0),
16154	Sign: D);
16155	if (A.isNaN())
16156	A = APFloat::copySign(Value: APFloat(A.getSemantics()), Sign: A);
16157	if (B.isNaN())
16158	B = APFloat::copySign(Value: APFloat(B.getSemantics()), Sign: B);
16159	Recalc = true;
16160	}
16161	if (!Recalc && (AC.isInfinity() || BD.isInfinity() || AD.isInfinity() ||
16162	BC.isInfinity())) {
16163	if (A.isNaN())
16164	A = APFloat::copySign(Value: APFloat(A.getSemantics()), Sign: A);
16165	if (B.isNaN())
16166	B = APFloat::copySign(Value: APFloat(B.getSemantics()), Sign: B);
16167	if (C.isNaN())
16168	C = APFloat::copySign(Value: APFloat(C.getSemantics()), Sign: C);
16169	if (D.isNaN())
16170	D = APFloat::copySign(Value: APFloat(D.getSemantics()), Sign: D);
16171	Recalc = true;
16172	}
16173	if (Recalc) {
16174	ResR = APFloat::getInf(Sem: A.getSemantics()) * (A * C - B * D);
16175	ResI = APFloat::getInf(Sem: A.getSemantics()) * (A * D + B * C);
16176	}
16177	}
16178	}
16179
16180	void HandleComplexComplexDiv(APFloat A, APFloat B, APFloat C, APFloat D,
16181	APFloat &ResR, APFloat &ResI) {
16182	// This is an implementation of complex division according to the
16183	// constraints laid out in C11 Annex G. The implementation uses the
16184	// following naming scheme:
16185	// (a + ib) / (c + id)
16186
16187	int DenomLogB = 0;
16188	APFloat MaxCD = maxnum(A: abs(X: C), B: abs(X: D));
16189	if (MaxCD.isFinite()) {
16190	DenomLogB = ilogb(Arg: MaxCD);
16191	C = scalbn(X: C, Exp: -DenomLogB, RM: APFloat::rmNearestTiesToEven);
16192	D = scalbn(X: D, Exp: -DenomLogB, RM: APFloat::rmNearestTiesToEven);
16193	}
16194	APFloat Denom = C * C + D * D;
16195	ResR =
16196	scalbn(X: (A * C + B * D) / Denom, Exp: -DenomLogB, RM: APFloat::rmNearestTiesToEven);
16197	ResI =
16198	scalbn(X: (B * C - A * D) / Denom, Exp: -DenomLogB, RM: APFloat::rmNearestTiesToEven);
16199	if (ResR.isNaN() && ResI.isNaN()) {
16200	if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) {
16201	ResR = APFloat::getInf(Sem: ResR.getSemantics(), Negative: C.isNegative()) * A;
16202	ResI = APFloat::getInf(Sem: ResR.getSemantics(), Negative: C.isNegative()) * B;
16203	} else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() &&
16204	D.isFinite()) {
16205	A = APFloat::copySign(Value: APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0),
16206	Sign: A);
16207	B = APFloat::copySign(Value: APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0),
16208	Sign: B);
16209	ResR = APFloat::getInf(Sem: ResR.getSemantics()) * (A * C + B * D);
16210	ResI = APFloat::getInf(Sem: ResI.getSemantics()) * (B * C - A * D);
16211	} else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) {
16212	C = APFloat::copySign(Value: APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0),
16213	Sign: C);
16214	D = APFloat::copySign(Value: APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0),
16215	Sign: D);
16216	ResR = APFloat::getZero(Sem: ResR.getSemantics()) * (A * C + B * D);
16217	ResI = APFloat::getZero(Sem: ResI.getSemantics()) * (B * C - A * D);
16218	}
16219	}
16220	}
16221
16222	bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
16223	if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
16224	return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
16225
16226	// Track whether the LHS or RHS is real at the type system level. When this is
16227	// the case we can simplify our evaluation strategy.
16228	bool LHSReal = false, RHSReal = false;
16229
16230	bool LHSOK;
16231	if (E->getLHS()->getType()->isRealFloatingType()) {
16232	LHSReal = true;
16233	APFloat &Real = Result.FloatReal;
16234	LHSOK = EvaluateFloat(E: E->getLHS(), Result&: Real, Info);
16235	if (LHSOK) {
16236	Result.makeComplexFloat();
16237	Result.FloatImag = APFloat(Real.getSemantics());
16238	}
16239	} else {
16240	LHSOK = Visit(E->getLHS());
16241	}
16242	if (!LHSOK && !Info.noteFailure())
16243	return false;
16244
16245	ComplexValue RHS;
16246	if (E->getRHS()->getType()->isRealFloatingType()) {
16247	RHSReal = true;
16248	APFloat &Real = RHS.FloatReal;
16249	if (!EvaluateFloat(E: E->getRHS(), Result&: Real, Info) || !LHSOK)
16250	return false;
16251	RHS.makeComplexFloat();
16252	RHS.FloatImag = APFloat(Real.getSemantics());
16253	} else if (!EvaluateComplex(E: E->getRHS(), Result&: RHS, Info) || !LHSOK)
16254	return false;
16255
16256	assert(!(LHSReal && RHSReal) &&
16257	"Cannot have both operands of a complex operation be real.");
16258	switch (E->getOpcode()) {
16259	default: return Error(E);
16260	case BO_Add:
16261	if (Result.isComplexFloat()) {
16262	Result.getComplexFloatReal().add(RHS: RHS.getComplexFloatReal(),
16263	RM: APFloat::rmNearestTiesToEven);
16264	if (LHSReal)
16265	Result.getComplexFloatImag() = RHS.getComplexFloatImag();
16266	else if (!RHSReal)
16267	Result.getComplexFloatImag().add(RHS: RHS.getComplexFloatImag(),
16268	RM: APFloat::rmNearestTiesToEven);
16269	} else {
16270	Result.getComplexIntReal() += RHS.getComplexIntReal();
16271	Result.getComplexIntImag() += RHS.getComplexIntImag();
16272	}
16273	break;
16274	case BO_Sub:
16275	if (Result.isComplexFloat()) {
16276	Result.getComplexFloatReal().subtract(RHS: RHS.getComplexFloatReal(),
16277	RM: APFloat::rmNearestTiesToEven);
16278	if (LHSReal) {
16279	Result.getComplexFloatImag() = RHS.getComplexFloatImag();
16280	Result.getComplexFloatImag().changeSign();
16281	} else if (!RHSReal) {
16282	Result.getComplexFloatImag().subtract(RHS: RHS.getComplexFloatImag(),
16283	RM: APFloat::rmNearestTiesToEven);
16284	}
16285	} else {
16286	Result.getComplexIntReal() -= RHS.getComplexIntReal();
16287	Result.getComplexIntImag() -= RHS.getComplexIntImag();
16288	}
16289	break;
16290	case BO_Mul:
16291	if (Result.isComplexFloat()) {
16292	// This is an implementation of complex multiplication according to the
16293	// constraints laid out in C11 Annex G. The implementation uses the
16294	// following naming scheme:
16295	// (a + ib) * (c + id)
16296	ComplexValue LHS = Result;
16297	APFloat &A = LHS.getComplexFloatReal();
16298	APFloat &B = LHS.getComplexFloatImag();
16299	APFloat &C = RHS.getComplexFloatReal();
16300	APFloat &D = RHS.getComplexFloatImag();
16301	APFloat &ResR = Result.getComplexFloatReal();
16302	APFloat &ResI = Result.getComplexFloatImag();
16303	if (LHSReal) {
16304	assert(!RHSReal && "Cannot have two real operands for a complex op!");
16305	ResR = A;
16306	ResI = A;
16307	// ResR = A * C;
16308	// ResI = A * D;
16309	if (!handleFloatFloatBinOp(Info, E, LHS&: ResR, Opcode: BO_Mul, RHS: C) ||
16310	!handleFloatFloatBinOp(Info, E, LHS&: ResI, Opcode: BO_Mul, RHS: D))
16311	return false;
16312	} else if (RHSReal) {
16313	// ResR = C * A;
16314	// ResI = C * B;
16315	ResR = C;
16316	ResI = C;
16317	if (!handleFloatFloatBinOp(Info, E, LHS&: ResR, Opcode: BO_Mul, RHS: A) ||
16318	!handleFloatFloatBinOp(Info, E, LHS&: ResI, Opcode: BO_Mul, RHS: B))
16319	return false;
16320	} else {
16321	HandleComplexComplexMul(A, B, C, D, ResR, ResI);
16322	}
16323	} else {
16324	ComplexValue LHS = Result;
16325	Result.getComplexIntReal() =
16326	(LHS.getComplexIntReal() * RHS.getComplexIntReal() -
16327	LHS.getComplexIntImag() * RHS.getComplexIntImag());
16328	Result.getComplexIntImag() =
16329	(LHS.getComplexIntReal() * RHS.getComplexIntImag() +
16330	LHS.getComplexIntImag() * RHS.getComplexIntReal());
16331	}
16332	break;
16333	case BO_Div:
16334	if (Result.isComplexFloat()) {
16335	// This is an implementation of complex division according to the
16336	// constraints laid out in C11 Annex G. The implementation uses the
16337	// following naming scheme:
16338	// (a + ib) / (c + id)
16339	ComplexValue LHS = Result;
16340	APFloat &A = LHS.getComplexFloatReal();
16341	APFloat &B = LHS.getComplexFloatImag();
16342	APFloat &C = RHS.getComplexFloatReal();
16343	APFloat &D = RHS.getComplexFloatImag();
16344	APFloat &ResR = Result.getComplexFloatReal();
16345	APFloat &ResI = Result.getComplexFloatImag();
16346	if (RHSReal) {
16347	ResR = A;
16348	ResI = B;
16349	// ResR = A / C;
16350	// ResI = B / C;
16351	if (!handleFloatFloatBinOp(Info, E, LHS&: ResR, Opcode: BO_Div, RHS: C) ||
16352	!handleFloatFloatBinOp(Info, E, LHS&: ResI, Opcode: BO_Div, RHS: C))
16353	return false;
16354	} else {
16355	if (LHSReal) {
16356	// No real optimizations we can do here, stub out with zero.
16357	B = APFloat::getZero(Sem: A.getSemantics());
16358	}
16359	HandleComplexComplexDiv(A, B, C, D, ResR, ResI);
16360	}
16361	} else {
16362	ComplexValue LHS = Result;
16363	APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() +
16364	RHS.getComplexIntImag() * RHS.getComplexIntImag();
16365	if (Den.isZero())
16366	return Error(E, diag::note_expr_divide_by_zero);
16367
16368	Result.getComplexIntReal() =
16369	(LHS.getComplexIntReal() * RHS.getComplexIntReal() +
16370	LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den;
16371	Result.getComplexIntImag() =
16372	(LHS.getComplexIntImag() * RHS.getComplexIntReal() -
16373	LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den;
16374	}
16375	break;
16376	}
16377
16378	return true;
16379	}
16380
16381	bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
16382	// Get the operand value into 'Result'.
16383	if (!Visit(E->getSubExpr()))
16384	return false;
16385
16386	switch (E->getOpcode()) {
16387	default:
16388	return Error(E);
16389	case UO_Extension:
16390	return true;
16391	case UO_Plus:
16392	// The result is always just the subexpr.
16393	return true;
16394	case UO_Minus:
16395	if (Result.isComplexFloat()) {
16396	Result.getComplexFloatReal().changeSign();
16397	Result.getComplexFloatImag().changeSign();
16398	}
16399	else {
16400	Result.getComplexIntReal() = -Result.getComplexIntReal();
16401	Result.getComplexIntImag() = -Result.getComplexIntImag();
16402	}
16403	return true;
16404	case UO_Not:
16405	if (Result.isComplexFloat())
16406	Result.getComplexFloatImag().changeSign();
16407	else
16408	Result.getComplexIntImag() = -Result.getComplexIntImag();
16409	return true;
16410	}
16411	}
16412
16413	bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
16414	if (E->getNumInits() == 2) {
16415	if (E->getType()->isComplexType()) {
16416	Result.makeComplexFloat();
16417	if (!EvaluateFloat(E: E->getInit(Init: 0), Result&: Result.FloatReal, Info))
16418	return false;
16419	if (!EvaluateFloat(E: E->getInit(Init: 1), Result&: Result.FloatImag, Info))
16420	return false;
16421	} else {
16422	Result.makeComplexInt();
16423	if (!EvaluateInteger(E: E->getInit(Init: 0), Result&: Result.IntReal, Info))
16424	return false;
16425	if (!EvaluateInteger(E: E->getInit(Init: 1), Result&: Result.IntImag, Info))
16426	return false;
16427	}
16428	return true;
16429	}
16430	return ExprEvaluatorBaseTy::VisitInitListExpr(E);
16431	}
16432
16433	bool ComplexExprEvaluator::VisitCallExpr(const CallExpr *E) {
16434	if (!IsConstantEvaluatedBuiltinCall(E))
16435	return ExprEvaluatorBaseTy::VisitCallExpr(E);
16436
16437	switch (E->getBuiltinCallee()) {
16438	case Builtin::BI__builtin_complex:
16439	Result.makeComplexFloat();
16440	if (!EvaluateFloat(E: E->getArg(Arg: 0), Result&: Result.FloatReal, Info))
16441	return false;
16442	if (!EvaluateFloat(E: E->getArg(Arg: 1), Result&: Result.FloatImag, Info))
16443	return false;
16444	return true;
16445
16446	default:
16447	return false;
16448	}
16449	}
16450
16451	//===----------------------------------------------------------------------===//
16452	// Atomic expression evaluation, essentially just handling the NonAtomicToAtomic
16453	// implicit conversion.
16454	//===----------------------------------------------------------------------===//
16455
16456	namespace {
16457	class AtomicExprEvaluator :
16458	public ExprEvaluatorBase<AtomicExprEvaluator> {
16459	const LValue *This;
16460	APValue &Result;
16461	public:
16462	AtomicExprEvaluator(EvalInfo &Info, const LValue *This, APValue &Result)
16463	: ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
16464
16465	bool Success(const APValue &V, const Expr *E) {
16466	Result = V;
16467	return true;
16468	}
16469
16470	bool ZeroInitialization(const Expr *E) {
16471	ImplicitValueInitExpr VIE(
16472	E->getType()->castAs<AtomicType>()->getValueType());
16473	// For atomic-qualified class (and array) types in C++, initialize the
16474	// _Atomic-wrapped subobject directly, in-place.
16475	return This ? EvaluateInPlace(Result, Info, *This, &VIE)
16476	: Evaluate(Result, Info, &VIE);
16477	}
16478
16479	bool VisitCastExpr(const CastExpr *E) {
16480	switch (E->getCastKind()) {
16481	default:
16482	return ExprEvaluatorBaseTy::VisitCastExpr(E);
16483	case CK_NullToPointer:
16484	VisitIgnoredValue(E: E->getSubExpr());
16485	return ZeroInitialization(E);
16486	case CK_NonAtomicToAtomic:
16487	return This ? EvaluateInPlace(Result, Info, This: *This, E: E->getSubExpr())
16488	: Evaluate(Result, Info, E: E->getSubExpr());
16489	}
16490	}
16491	};
16492	} // end anonymous namespace
16493
16494	static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
16495	EvalInfo &Info) {
16496	assert(!E->isValueDependent());
16497	assert(E->isPRValue() && E->getType()->isAtomicType());
16498	return AtomicExprEvaluator(Info, This, Result).Visit(E);
16499	}
16500
16501	//===----------------------------------------------------------------------===//
16502	// Void expression evaluation, primarily for a cast to void on the LHS of a
16503	// comma operator
16504	//===----------------------------------------------------------------------===//
16505
16506	namespace {
16507	class VoidExprEvaluator
16508	: public ExprEvaluatorBase<VoidExprEvaluator> {
16509	public:
16510	VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {}
16511
16512	bool Success(const APValue &V, const Expr *e) { return true; }
16513
16514	bool ZeroInitialization(const Expr *E) { return true; }
16515
16516	bool VisitCastExpr(const CastExpr *E) {
16517	switch (E->getCastKind()) {
16518	default:
16519	return ExprEvaluatorBaseTy::VisitCastExpr(E);
16520	case CK_ToVoid:
16521	VisitIgnoredValue(E: E->getSubExpr());
16522	return true;
16523	}
16524	}
16525
16526	bool VisitCallExpr(const CallExpr *E) {
16527	if (!IsConstantEvaluatedBuiltinCall(E))
16528	return ExprEvaluatorBaseTy::VisitCallExpr(E);
16529
16530	switch (E->getBuiltinCallee()) {
16531	case Builtin::BI__assume:
16532	case Builtin::BI__builtin_assume:
16533	// The argument is not evaluated!
16534	return true;
16535
16536	case Builtin::BI__builtin_operator_delete:
16537	return HandleOperatorDeleteCall(Info, E);
16538
16539	default:
16540	return false;
16541	}
16542	}
16543
16544	bool VisitCXXDeleteExpr(const CXXDeleteExpr *E);
16545	};
16546	} // end anonymous namespace
16547
16548	bool VoidExprEvaluator::VisitCXXDeleteExpr(const CXXDeleteExpr *E) {
16549	// We cannot speculatively evaluate a delete expression.
16550	if (Info.SpeculativeEvaluationDepth)
16551	return false;
16552
16553	FunctionDecl *OperatorDelete = E->getOperatorDelete();
16554	if (!OperatorDelete
16555	->isUsableAsGlobalAllocationFunctionInConstantEvaluation()) {
16556	Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
16557	<< isa<CXXMethodDecl>(OperatorDelete) << OperatorDelete;
16558	return false;
16559	}
16560
16561	const Expr *Arg = E->getArgument();
16562
16563	LValue Pointer;
16564	if (!EvaluatePointer(E: Arg, Result&: Pointer, Info))
16565	return false;
16566	if (Pointer.Designator.Invalid)
16567	return false;
16568
16569	// Deleting a null pointer has no effect.
16570	if (Pointer.isNullPointer()) {
16571	// This is the only case where we need to produce an extension warning:
16572	// the only other way we can succeed is if we find a dynamic allocation,
16573	// and we will have warned when we allocated it in that case.
16574	if (!Info.getLangOpts().CPlusPlus20)
16575	Info.CCEDiag(E, diag::note_constexpr_new);
16576	return true;
16577	}
16578
16579	std::optional<DynAlloc *> Alloc = CheckDeleteKind(
16580	Info, E, Pointer, E->isArrayForm() ? DynAlloc::ArrayNew : DynAlloc::New);
16581	if (!Alloc)
16582	return false;
16583	QualType AllocType = Pointer.Base.getDynamicAllocType();
16584
16585	// For the non-array case, the designator must be empty if the static type
16586	// does not have a virtual destructor.
16587	if (!E->isArrayForm() && Pointer.Designator.Entries.size() != 0 &&
16588	!hasVirtualDestructor(T: Arg->getType()->getPointeeType())) {
16589	Info.FFDiag(E, diag::note_constexpr_delete_base_nonvirt_dtor)
16590	<< Arg->getType()->getPointeeType() << AllocType;
16591	return false;
16592	}
16593
16594	// For a class type with a virtual destructor, the selected operator delete
16595	// is the one looked up when building the destructor.
16596	if (!E->isArrayForm() && !E->isGlobalDelete()) {
16597	const FunctionDecl *VirtualDelete = getVirtualOperatorDelete(T: AllocType);
16598	if (VirtualDelete &&
16599	!VirtualDelete
16600	->isUsableAsGlobalAllocationFunctionInConstantEvaluation()) {
16601	Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
16602	<< isa<CXXMethodDecl>(VirtualDelete) << VirtualDelete;
16603	return false;
16604	}
16605	}
16606
16607	if (!HandleDestruction(Info, E->getExprLoc(), Pointer.getLValueBase(),
16608	(*Alloc)->Value, AllocType))
16609	return false;
16610
16611	if (!Info.HeapAllocs.erase(x: Pointer.Base.dyn_cast<DynamicAllocLValue>())) {
16612	// The element was already erased. This means the destructor call also
16613	// deleted the object.
16614	// FIXME: This probably results in undefined behavior before we get this
16615	// far, and should be diagnosed elsewhere first.
16616	Info.FFDiag(E, diag::note_constexpr_double_delete);
16617	return false;
16618	}
16619
16620	return true;
16621	}
16622
16623	static bool EvaluateVoid(const Expr *E, EvalInfo &Info) {
16624	assert(!E->isValueDependent());
16625	assert(E->isPRValue() && E->getType()->isVoidType());
16626	return VoidExprEvaluator(Info).Visit(E);
16627	}
16628
16629	//===----------------------------------------------------------------------===//
16630	// Top level Expr::EvaluateAsRValue method.
16631	//===----------------------------------------------------------------------===//
16632
16633	static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
16634	assert(!E->isValueDependent());
16635	// In C, function designators are not lvalues, but we evaluate them as if they
16636	// are.
16637	QualType T = E->getType();
16638	if (E->isGLValue() || T->isFunctionType()) {
16639	LValue LV;
16640	if (!EvaluateLValue(E, Result&: LV, Info))
16641	return false;
16642	LV.moveInto(V&: Result);
16643	} else if (T->isVectorType()) {
16644	if (!EvaluateVector(E, Result, Info))
16645	return false;
16646	} else if (T->isIntegralOrEnumerationType()) {
16647	if (!IntExprEvaluator(Info, Result).Visit(E))
16648	return false;
16649	} else if (T->hasPointerRepresentation()) {
16650	LValue LV;
16651	if (!EvaluatePointer(E, Result&: LV, Info))
16652	return false;
16653	LV.moveInto(V&: Result);
16654	} else if (T->isRealFloatingType()) {
16655	llvm::APFloat F(0.0);
16656	if (!EvaluateFloat(E, Result&: F, Info))
16657	return false;
16658	Result = APValue(F);
16659	} else if (T->isAnyComplexType()) {
16660	ComplexValue C;
16661	if (!EvaluateComplex(E, Result&: C, Info))
16662	return false;
16663	C.moveInto(v&: Result);
16664	} else if (T->isFixedPointType()) {
16665	if (!FixedPointExprEvaluator(Info, Result).Visit(E)) return false;
16666	} else if (T->isMemberPointerType()) {
16667	MemberPtr P;
16668	if (!EvaluateMemberPointer(E, Result&: P, Info))
16669	return false;
16670	P.moveInto(V&: Result);
16671	return true;
16672	} else if (T->isArrayType()) {
16673	LValue LV;
16674	APValue &Value =
16675	Info.CurrentCall->createTemporary(Key: E, T, Scope: ScopeKind::FullExpression, LV);
16676	if (!EvaluateArray(E, This: LV, Result&: Value, Info))
16677	return false;
16678	Result = Value;
16679	} else if (T->isRecordType()) {
16680	LValue LV;
16681	APValue &Value =
16682	Info.CurrentCall->createTemporary(Key: E, T, Scope: ScopeKind::FullExpression, LV);
16683	if (!EvaluateRecord(E, This: LV, Result&: Value, Info))
16684	return false;
16685	Result = Value;
16686	} else if (T->isVoidType()) {
16687	if (!Info.getLangOpts().CPlusPlus11)
16688	Info.CCEDiag(E, diag::note_constexpr_nonliteral)
16689	<< E->getType();
16690	if (!EvaluateVoid(E, Info))
16691	return false;
16692	} else if (T->isAtomicType()) {
16693	QualType Unqual = T.getAtomicUnqualifiedType();
16694	if (Unqual->isArrayType() || Unqual->isRecordType()) {
16695	LValue LV;
16696	APValue &Value = Info.CurrentCall->createTemporary(
16697	Key: E, T: Unqual, Scope: ScopeKind::FullExpression, LV);
16698	if (!EvaluateAtomic(E, This: &LV, Result&: Value, Info))
16699	return false;
16700	Result = Value;
16701	} else {
16702	if (!EvaluateAtomic(E, This: nullptr, Result, Info))
16703	return false;
16704	}
16705	} else if (Info.getLangOpts().CPlusPlus11) {
16706	Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType();
16707	return false;
16708	} else {
16709	Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
16710	return false;
16711	}
16712
16713	return true;
16714	}
16715
16716	/// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some
16717	/// cases, the in-place evaluation is essential, since later initializers for
16718	/// an object can indirectly refer to subobjects which were initialized earlier.
16719	static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This,
16720	const Expr *E, bool AllowNonLiteralTypes) {
16721	assert(!E->isValueDependent());
16722
16723	if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, This: &This))
16724	return false;
16725
16726	if (E->isPRValue()) {
16727	// Evaluate arrays and record types in-place, so that later initializers can
16728	// refer to earlier-initialized members of the object.
16729	QualType T = E->getType();
16730	if (T->isArrayType())
16731	return EvaluateArray(E, This, Result, Info);
16732	else if (T->isRecordType())
16733	return EvaluateRecord(E, This, Result, Info);
16734	else if (T->isAtomicType()) {
16735	QualType Unqual = T.getAtomicUnqualifiedType();
16736	if (Unqual->isArrayType() || Unqual->isRecordType())
16737	return EvaluateAtomic(E, This: &This, Result, Info);
16738	}
16739	}
16740
16741	// For any other type, in-place evaluation is unimportant.
16742	return Evaluate(Result, Info, E);
16743	}
16744
16745	/// EvaluateAsRValue - Try to evaluate this expression, performing an implicit
16746	/// lvalue-to-rvalue cast if it is an lvalue.
16747	static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) {
16748	assert(!E->isValueDependent());
16749
16750	if (E->getType().isNull())
16751	return false;
16752
16753	if (!CheckLiteralType(Info, E))
16754	return false;
16755
16756	if (Info.EnableNewConstInterp) {
16757	if (!Info.Ctx.getInterpContext().evaluateAsRValue(Parent&: Info, E, Result))
16758	return false;
16759	return CheckConstantExpression(Info, DiagLoc: E->getExprLoc(), Type: E->getType(), Value: Result,
16760	Kind: ConstantExprKind::Normal);
16761	}
16762
16763	if (!::Evaluate(Result, Info, E))
16764	return false;
16765
16766	// Implicit lvalue-to-rvalue cast.
16767	if (E->isGLValue()) {
16768	LValue LV;
16769	LV.setFrom(Ctx&: Info.Ctx, V: Result);
16770	if (!handleLValueToRValueConversion(Info, Conv: E, Type: E->getType(), LVal: LV, RVal&: Result))
16771	return false;
16772	}
16773
16774	// Check this core constant expression is a constant expression.
16775	return CheckConstantExpression(Info, DiagLoc: E->getExprLoc(), Type: E->getType(), Value: Result,
16776	Kind: ConstantExprKind::Normal) &&
16777	CheckMemoryLeaks(Info);
16778	}
16779
16780	static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result,
16781	const ASTContext &Ctx, bool &IsConst) {
16782	// Fast-path evaluations of integer literals, since we sometimes see files
16783	// containing vast quantities of these.
16784	if (const auto *L = dyn_cast<IntegerLiteral>(Val: Exp)) {
16785	Result.Val = APValue(APSInt(L->getValue(),
16786	L->getType()->isUnsignedIntegerType()));
16787	IsConst = true;
16788	return true;
16789	}
16790
16791	if (const auto *L = dyn_cast<CXXBoolLiteralExpr>(Val: Exp)) {
16792	Result.Val = APValue(APSInt(APInt(1, L->getValue())));
16793	IsConst = true;
16794	return true;
16795	}
16796
16797	if (const auto *FL = dyn_cast<FloatingLiteral>(Val: Exp)) {
16798	Result.Val = APValue(FL->getValue());
16799	IsConst = true;
16800	return true;
16801	}
16802
16803	if (const auto *L = dyn_cast<CharacterLiteral>(Val: Exp)) {
16804	Result.Val = APValue(Ctx.MakeIntValue(Value: L->getValue(), Type: L->getType()));
16805	IsConst = true;
16806	return true;
16807	}
16808
16809	if (const auto *CE = dyn_cast<ConstantExpr>(Val: Exp)) {
16810	if (CE->hasAPValueResult()) {
16811	APValue APV = CE->getAPValueResult();
16812	if (!APV.isLValue()) {
16813	Result.Val = std::move(APV);
16814	IsConst = true;
16815	return true;
16816	}
16817	}
16818
16819	// The SubExpr is usually just an IntegerLiteral.
16820	return FastEvaluateAsRValue(CE->getSubExpr(), Result, Ctx, IsConst);
16821	}
16822
16823	// This case should be rare, but we need to check it before we check on
16824	// the type below.
16825	if (Exp->getType().isNull()) {
16826	IsConst = false;
16827	return true;
16828	}
16829
16830	return false;
16831	}
16832
16833	static bool hasUnacceptableSideEffect(Expr::EvalStatus &Result,
16834	Expr::SideEffectsKind SEK) {
16835	return (SEK < Expr::SE_AllowSideEffects && Result.HasSideEffects) ||
16836	(SEK < Expr::SE_AllowUndefinedBehavior && Result.HasUndefinedBehavior);
16837	}
16838
16839	static bool EvaluateAsRValue(const Expr *E, Expr::EvalResult &Result,
16840	const ASTContext &Ctx, EvalInfo &Info) {
16841	assert(!E->isValueDependent());
16842	bool IsConst;
16843	if (FastEvaluateAsRValue(Exp: E, Result, Ctx, IsConst))
16844	return IsConst;
16845
16846	return EvaluateAsRValue(Info, E, Result&: Result.Val);
16847	}
16848
16849	static bool EvaluateAsInt(const Expr *E, Expr::EvalResult &ExprResult,
16850	const ASTContext &Ctx,
16851	Expr::SideEffectsKind AllowSideEffects,
16852	EvalInfo &Info) {
16853	assert(!E->isValueDependent());
16854	if (!E->getType()->isIntegralOrEnumerationType())
16855	return false;
16856
16857	if (!::EvaluateAsRValue(E, Result&: ExprResult, Ctx, Info) ||
16858	!ExprResult.Val.isInt() ||
16859	hasUnacceptableSideEffect(Result&: ExprResult, SEK: AllowSideEffects))
16860	return false;
16861
16862	return true;
16863	}
16864
16865	static bool EvaluateAsFixedPoint(const Expr *E, Expr::EvalResult &ExprResult,
16866	const ASTContext &Ctx,
16867	Expr::SideEffectsKind AllowSideEffects,
16868	EvalInfo &Info) {
16869	assert(!E->isValueDependent());
16870	if (!E->getType()->isFixedPointType())
16871	return false;
16872
16873	if (!::EvaluateAsRValue(E, Result&: ExprResult, Ctx, Info))
16874	return false;
16875
16876	if (!ExprResult.Val.isFixedPoint() ||
16877	hasUnacceptableSideEffect(Result&: ExprResult, SEK: AllowSideEffects))
16878	return false;
16879
16880	return true;
16881	}
16882
16883	/// EvaluateAsRValue - Return true if this is a constant which we can fold using
16884	/// any crazy technique (that has nothing to do with language standards) that
16885	/// we want to. If this function returns true, it returns the folded constant
16886	/// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion
16887	/// will be applied to the result.
16888	bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx,
16889	bool InConstantContext) const {
16890	assert(!isValueDependent() &&
16891	"Expression evaluator can't be called on a dependent expression.");
16892	ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsRValue");
16893	EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
16894	Info.InConstantContext = InConstantContext;
16895	return ::EvaluateAsRValue(E: this, Result, Ctx, Info);
16896	}
16897
16898	bool Expr::EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx,
16899	bool InConstantContext) const {
16900	assert(!isValueDependent() &&
16901	"Expression evaluator can't be called on a dependent expression.");
16902	ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsBooleanCondition");
16903	EvalResult Scratch;
16904	return EvaluateAsRValue(Result&: Scratch, Ctx, InConstantContext) &&
16905	HandleConversionToBool(Val: Scratch.Val, Result);
16906	}
16907
16908	bool Expr::EvaluateAsInt(EvalResult &Result, const ASTContext &Ctx,
16909	SideEffectsKind AllowSideEffects,
16910	bool InConstantContext) const {
16911	assert(!isValueDependent() &&
16912	"Expression evaluator can't be called on a dependent expression.");
16913	ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsInt");
16914	EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
16915	Info.InConstantContext = InConstantContext;
16916	return ::EvaluateAsInt(E: this, ExprResult&: Result, Ctx, AllowSideEffects, Info);
16917	}
16918
16919	bool Expr::EvaluateAsFixedPoint(EvalResult &Result, const ASTContext &Ctx,
16920	SideEffectsKind AllowSideEffects,
16921	bool InConstantContext) const {
16922	assert(!isValueDependent() &&
16923	"Expression evaluator can't be called on a dependent expression.");
16924	ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsFixedPoint");
16925	EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
16926	Info.InConstantContext = InConstantContext;
16927	return ::EvaluateAsFixedPoint(E: this, ExprResult&: Result, Ctx, AllowSideEffects, Info);
16928	}
16929
16930	bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx,
16931	SideEffectsKind AllowSideEffects,
16932	bool InConstantContext) const {
16933	assert(!isValueDependent() &&
16934	"Expression evaluator can't be called on a dependent expression.");
16935
16936	if (!getType()->isRealFloatingType())
16937	return false;
16938
16939	ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsFloat");
16940	EvalResult ExprResult;
16941	if (!EvaluateAsRValue(Result&: ExprResult, Ctx, InConstantContext) ||
16942	!ExprResult.Val.isFloat() ||
16943	hasUnacceptableSideEffect(Result&: ExprResult, SEK: AllowSideEffects))
16944	return false;
16945
16946	Result = ExprResult.Val.getFloat();
16947	return true;
16948	}
16949
16950	bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx,
16951	bool InConstantContext) const {
16952	assert(!isValueDependent() &&
16953	"Expression evaluator can't be called on a dependent expression.");
16954
16955	ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsLValue");
16956	EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold);
16957	Info.InConstantContext = InConstantContext;
16958	LValue LV;
16959	CheckedTemporaries CheckedTemps;
16960	if (!EvaluateLValue(E: this, Result&: LV, Info) || !Info.discardCleanups() ||
16961	Result.HasSideEffects ||
16962	!CheckLValueConstantExpression(Info, Loc: getExprLoc(),
16963	Type: Ctx.getLValueReferenceType(T: getType()), LVal: LV,
16964	Kind: ConstantExprKind::Normal, CheckedTemps))
16965	return false;
16966
16967	LV.moveInto(V&: Result.Val);
16968	return true;
16969	}
16970
16971	static bool EvaluateDestruction(const ASTContext &Ctx, APValue::LValueBase Base,
16972	APValue DestroyedValue, QualType Type,
16973	SourceLocation Loc, Expr::EvalStatus &EStatus,
16974	bool IsConstantDestruction) {
16975	EvalInfo Info(Ctx, EStatus,
16976	IsConstantDestruction ? EvalInfo::EM_ConstantExpression
16977	: EvalInfo::EM_ConstantFold);
16978	Info.setEvaluatingDecl(Base, Value&: DestroyedValue,
16979	EDK: EvalInfo::EvaluatingDeclKind::Dtor);
16980	Info.InConstantContext = IsConstantDestruction;
16981
16982	LValue LVal;
16983	LVal.set(B: Base);
16984
16985	if (!HandleDestruction(Info, Loc, LVBase: Base, Value&: DestroyedValue, T: Type) ||
16986	EStatus.HasSideEffects)
16987	return false;
16988
16989	if (!Info.discardCleanups())
16990	llvm_unreachable("Unhandled cleanup; missing full expression marker?");
16991
16992	return true;
16993	}
16994
16995	bool Expr::EvaluateAsConstantExpr(EvalResult &Result, const ASTContext &Ctx,
16996	ConstantExprKind Kind) const {
16997	assert(!isValueDependent() &&
16998	"Expression evaluator can't be called on a dependent expression.");
16999	bool IsConst;
17000	if (FastEvaluateAsRValue(Exp: this, Result, Ctx, IsConst) && Result.Val.hasValue())
17001	return true;
17002
17003	ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateAsConstantExpr");
17004	EvalInfo::EvaluationMode EM = EvalInfo::EM_ConstantExpression;
17005	EvalInfo Info(Ctx, Result, EM);
17006	Info.InConstantContext = true;
17007
17008	if (Info.EnableNewConstInterp) {
17009	if (!Info.Ctx.getInterpContext().evaluate(Parent&: Info, E: this, Result&: Result.Val, Kind))
17010	return false;
17011	return CheckConstantExpression(Info, DiagLoc: getExprLoc(),
17012	Type: getStorageType(Ctx, E: this), Value: Result.Val, Kind);
17013	}
17014
17015	// The type of the object we're initializing is 'const T' for a class NTTP.
17016	QualType T = getType();
17017	if (Kind == ConstantExprKind::ClassTemplateArgument)
17018	T.addConst();
17019
17020	// If we're evaluating a prvalue, fake up a MaterializeTemporaryExpr to
17021	// represent the result of the evaluation. CheckConstantExpression ensures
17022	// this doesn't escape.
17023	MaterializeTemporaryExpr BaseMTE(T, const_cast<Expr*>(this), true);
17024	APValue::LValueBase Base(&BaseMTE);
17025	Info.setEvaluatingDecl(Base, Value&: Result.Val);
17026
17027	LValue LVal;
17028	LVal.set(B: Base);
17029	// C++23 [intro.execution]/p5
17030	// A full-expression is [...] a constant-expression
17031	// So we need to make sure temporary objects are destroyed after having
17032	// evaluating the expression (per C++23 [class.temporary]/p4).
17033	FullExpressionRAII Scope(Info);
17034	if (!::EvaluateInPlace(Result&: Result.Val, Info, This: LVal, E: this) ||
17035	Result.HasSideEffects || !Scope.destroy())
17036	return false;
17037
17038	if (!Info.discardCleanups())
17039	llvm_unreachable("Unhandled cleanup; missing full expression marker?");
17040
17041	if (!CheckConstantExpression(Info, DiagLoc: getExprLoc(), Type: getStorageType(Ctx, E: this),
17042	Value: Result.Val, Kind))
17043	return false;
17044	if (!CheckMemoryLeaks(Info))
17045	return false;
17046
17047	// If this is a class template argument, it's required to have constant
17048	// destruction too.
17049	if (Kind == ConstantExprKind::ClassTemplateArgument &&
17050	(!EvaluateDestruction(Ctx, Base, Result.Val, T, getBeginLoc(), Result,
17051	true) ||
17052	Result.HasSideEffects)) {
17053	// FIXME: Prefix a note to indicate that the problem is lack of constant
17054	// destruction.
17055	return false;
17056	}
17057
17058	return true;
17059	}
17060
17061	bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx,
17062	const VarDecl *VD,
17063	SmallVectorImpl<PartialDiagnosticAt> &Notes,
17064	bool IsConstantInitialization) const {
17065	assert(!isValueDependent() &&
17066	"Expression evaluator can't be called on a dependent expression.");
17067
17068	llvm::TimeTraceScope TimeScope("EvaluateAsInitializer", [&] {
17069	std::string Name;
17070	llvm::raw_string_ostream OS(Name);
17071	VD->printQualifiedName(OS);
17072	return Name;
17073	});
17074
17075	Expr::EvalStatus EStatus;
17076	EStatus.Diag = &Notes;
17077
17078	EvalInfo Info(Ctx, EStatus,
17079	(IsConstantInitialization &&
17080	(Ctx.getLangOpts().CPlusPlus || Ctx.getLangOpts().C23))
17081	? EvalInfo::EM_ConstantExpression
17082	: EvalInfo::EM_ConstantFold);
17083	Info.setEvaluatingDecl(VD, Value);
17084	Info.InConstantContext = IsConstantInitialization;
17085
17086	SourceLocation DeclLoc = VD->getLocation();
17087	QualType DeclTy = VD->getType();
17088
17089	if (Info.EnableNewConstInterp) {
17090	auto &InterpCtx = const_cast<ASTContext &>(Ctx).getInterpContext();
17091	if (!InterpCtx.evaluateAsInitializer(Parent&: Info, VD, Result&: Value))
17092	return false;
17093
17094	return CheckConstantExpression(Info, DiagLoc: DeclLoc, Type: DeclTy, Value,
17095	Kind: ConstantExprKind::Normal);
17096	} else {
17097	LValue LVal;
17098	LVal.set(VD);
17099
17100	{
17101	// C++23 [intro.execution]/p5
17102	// A full-expression is ... an init-declarator ([dcl.decl]) or a
17103	// mem-initializer.
17104	// So we need to make sure temporary objects are destroyed after having
17105	// evaluated the expression (per C++23 [class.temporary]/p4).
17106	//
17107	// FIXME: Otherwise this may break test/Modules/pr68702.cpp because the
17108	// serialization code calls ParmVarDecl::getDefaultArg() which strips the
17109	// outermost FullExpr, such as ExprWithCleanups.
17110	FullExpressionRAII Scope(Info);
17111	if (!EvaluateInPlace(Result&: Value, Info, This: LVal, E: this,
17112	/*AllowNonLiteralTypes=*/true) ||
17113	EStatus.HasSideEffects)
17114	return false;
17115	}
17116
17117	// At this point, any lifetime-extended temporaries are completely
17118	// initialized.
17119	Info.performLifetimeExtension();
17120
17121	if (!Info.discardCleanups())
17122	llvm_unreachable("Unhandled cleanup; missing full expression marker?");
17123	}
17124
17125	return CheckConstantExpression(Info, DiagLoc: DeclLoc, Type: DeclTy, Value,
17126	Kind: ConstantExprKind::Normal) &&
17127	CheckMemoryLeaks(Info);
17128	}
17129
17130	bool VarDecl::evaluateDestruction(
17131	SmallVectorImpl<PartialDiagnosticAt> &Notes) const {
17132	Expr::EvalStatus EStatus;
17133	EStatus.Diag = &Notes;
17134
17135	// Only treat the destruction as constant destruction if we formally have
17136	// constant initialization (or are usable in a constant expression).
17137	bool IsConstantDestruction = hasConstantInitialization();
17138
17139	// Make a copy of the value for the destructor to mutate, if we know it.
17140	// Otherwise, treat the value as default-initialized; if the destructor works
17141	// anyway, then the destruction is constant (and must be essentially empty).
17142	APValue DestroyedValue;
17143	if (getEvaluatedValue() && !getEvaluatedValue()->isAbsent())
17144	DestroyedValue = *getEvaluatedValue();
17145	else if (!handleDefaultInitValue(getType(), DestroyedValue))
17146	return false;
17147
17148	if (!EvaluateDestruction(getASTContext(), this, std::move(DestroyedValue),
17149	getType(), getLocation(), EStatus,
17150	IsConstantDestruction) ||
17151	EStatus.HasSideEffects)
17152	return false;
17153
17154	ensureEvaluatedStmt()->HasConstantDestruction = true;
17155	return true;
17156	}
17157
17158	/// isEvaluatable - Call EvaluateAsRValue to see if this expression can be
17159	/// constant folded, but discard the result.
17160	bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const {
17161	assert(!isValueDependent() &&
17162	"Expression evaluator can't be called on a dependent expression.");
17163
17164	EvalResult Result;
17165	return EvaluateAsRValue(Result, Ctx, /* in constant context */ InConstantContext: true) &&
17166	!hasUnacceptableSideEffect(Result, SEK);
17167	}
17168
17169	APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx,
17170	SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
17171	assert(!isValueDependent() &&
17172	"Expression evaluator can't be called on a dependent expression.");
17173
17174	ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateKnownConstInt");
17175	EvalResult EVResult;
17176	EVResult.Diag = Diag;
17177	EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
17178	Info.InConstantContext = true;
17179
17180	bool Result = ::EvaluateAsRValue(E: this, Result&: EVResult, Ctx, Info);
17181	(void)Result;
17182	assert(Result && "Could not evaluate expression");
17183	assert(EVResult.Val.isInt() && "Expression did not evaluate to integer");
17184
17185	return EVResult.Val.getInt();
17186	}
17187
17188	APSInt Expr::EvaluateKnownConstIntCheckOverflow(
17189	const ASTContext &Ctx, SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
17190	assert(!isValueDependent() &&
17191	"Expression evaluator can't be called on a dependent expression.");
17192
17193	ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateKnownConstIntCheckOverflow");
17194	EvalResult EVResult;
17195	EVResult.Diag = Diag;
17196	EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
17197	Info.InConstantContext = true;
17198	Info.CheckingForUndefinedBehavior = true;
17199
17200	bool Result = ::EvaluateAsRValue(Info, E: this, Result&: EVResult.Val);
17201	(void)Result;
17202	assert(Result && "Could not evaluate expression");
17203	assert(EVResult.Val.isInt() && "Expression did not evaluate to integer");
17204
17205	return EVResult.Val.getInt();
17206	}
17207
17208	void Expr::EvaluateForOverflow(const ASTContext &Ctx) const {
17209	assert(!isValueDependent() &&
17210	"Expression evaluator can't be called on a dependent expression.");
17211
17212	ExprTimeTraceScope TimeScope(this, Ctx, "EvaluateForOverflow");
17213	bool IsConst;
17214	EvalResult EVResult;
17215	if (!FastEvaluateAsRValue(Exp: this, Result&: EVResult, Ctx, IsConst)) {
17216	EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
17217	Info.CheckingForUndefinedBehavior = true;
17218	(void)::EvaluateAsRValue(Info, E: this, Result&: EVResult.Val);
17219	}
17220	}
17221
17222	bool Expr::EvalResult::isGlobalLValue() const {
17223	assert(Val.isLValue());
17224	return IsGlobalLValue(B: Val.getLValueBase());
17225	}
17226
17227	/// isIntegerConstantExpr - this recursive routine will test if an expression is
17228	/// an integer constant expression.
17229
17230	/// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero,
17231	/// comma, etc
17232
17233	// CheckICE - This function does the fundamental ICE checking: the returned
17234	// ICEDiag contains an ICEKind indicating whether the expression is an ICE,
17235	// and a (possibly null) SourceLocation indicating the location of the problem.
17236	//
17237	// Note that to reduce code duplication, this helper does no evaluation
17238	// itself; the caller checks whether the expression is evaluatable, and
17239	// in the rare cases where CheckICE actually cares about the evaluated
17240	// value, it calls into Evaluate.
17241
17242	namespace {
17243
17244	enum ICEKind {
17245	/// This expression is an ICE.
17246	IK_ICE,
17247	/// This expression is not an ICE, but if it isn't evaluated, it's
17248	/// a legal subexpression for an ICE. This return value is used to handle
17249	/// the comma operator in C99 mode, and non-constant subexpressions.
17250	IK_ICEIfUnevaluated,
17251	/// This expression is not an ICE, and is not a legal subexpression for one.
17252	IK_NotICE
17253	};
17254
17255	struct ICEDiag {
17256	ICEKind Kind;
17257	SourceLocation Loc;
17258
17259	ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {}
17260	};
17261
17262	}
17263
17264	static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); }
17265
17266	static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; }
17267
17268	static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) {
17269	Expr::EvalResult EVResult;
17270	Expr::EvalStatus Status;
17271	EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
17272
17273	Info.InConstantContext = true;
17274	if (!::EvaluateAsRValue(E, Result&: EVResult, Ctx, Info) || EVResult.HasSideEffects ||
17275	!EVResult.Val.isInt())
17276	return ICEDiag(IK_NotICE, E->getBeginLoc());
17277
17278	return NoDiag();
17279	}
17280
17281	static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
17282	assert(!E->isValueDependent() && "Should not see value dependent exprs!");
17283	if (!E->getType()->isIntegralOrEnumerationType())
17284	return ICEDiag(IK_NotICE, E->getBeginLoc());
17285
17286	switch (E->getStmtClass()) {
17287	#define ABSTRACT_STMT(Node)
17288	#define STMT(Node, Base) case Expr::Node##Class:
17289	#define EXPR(Node, Base)
17290	#include "clang/AST/StmtNodes.inc"
17291	case Expr::PredefinedExprClass:
17292	case Expr::FloatingLiteralClass:
17293	case Expr::ImaginaryLiteralClass:
17294	case Expr::StringLiteralClass:
17295	case Expr::ArraySubscriptExprClass:
17296	case Expr::MatrixSubscriptExprClass:
17297	case Expr::ArraySectionExprClass:
17298	case Expr::OMPArrayShapingExprClass:
17299	case Expr::OMPIteratorExprClass:
17300	case Expr::MemberExprClass:
17301	case Expr::CompoundAssignOperatorClass:
17302	case Expr::CompoundLiteralExprClass:
17303	case Expr::ExtVectorElementExprClass:
17304	case Expr::DesignatedInitExprClass:
17305	case Expr::ArrayInitLoopExprClass:
17306	case Expr::ArrayInitIndexExprClass:
17307	case Expr::NoInitExprClass:
17308	case Expr::DesignatedInitUpdateExprClass:
17309	case Expr::ImplicitValueInitExprClass:
17310	case Expr::ParenListExprClass:
17311	case Expr::VAArgExprClass:
17312	case Expr::AddrLabelExprClass:
17313	case Expr::StmtExprClass:
17314	case Expr::CXXMemberCallExprClass:
17315	case Expr::CUDAKernelCallExprClass:
17316	case Expr::CXXAddrspaceCastExprClass:
17317	case Expr::CXXDynamicCastExprClass:
17318	case Expr::CXXTypeidExprClass:
17319	case Expr::CXXUuidofExprClass:
17320	case Expr::MSPropertyRefExprClass:
17321	case Expr::MSPropertySubscriptExprClass:
17322	case Expr::CXXNullPtrLiteralExprClass:
17323	case Expr::UserDefinedLiteralClass:
17324	case Expr::CXXThisExprClass:
17325	case Expr::CXXThrowExprClass:
17326	case Expr::CXXNewExprClass:
17327	case Expr::CXXDeleteExprClass:
17328	case Expr::CXXPseudoDestructorExprClass:
17329	case Expr::UnresolvedLookupExprClass:
17330	case Expr::TypoExprClass:
17331	case Expr::RecoveryExprClass:
17332	case Expr::DependentScopeDeclRefExprClass:
17333	case Expr::CXXConstructExprClass:
17334	case Expr::CXXInheritedCtorInitExprClass:
17335	case Expr::CXXStdInitializerListExprClass:
17336	case Expr::CXXBindTemporaryExprClass:
17337	case Expr::ExprWithCleanupsClass:
17338	case Expr::CXXTemporaryObjectExprClass:
17339	case Expr::CXXUnresolvedConstructExprClass:
17340	case Expr::CXXDependentScopeMemberExprClass:
17341	case Expr::UnresolvedMemberExprClass:
17342	case Expr::ObjCStringLiteralClass:
17343	case Expr::ObjCBoxedExprClass:
17344	case Expr::ObjCArrayLiteralClass:
17345	case Expr::ObjCDictionaryLiteralClass:
17346	case Expr::ObjCEncodeExprClass:
17347	case Expr::ObjCMessageExprClass:
17348	case Expr::ObjCSelectorExprClass:
17349	case Expr::ObjCProtocolExprClass:
17350	case Expr::ObjCIvarRefExprClass:
17351	case Expr::ObjCPropertyRefExprClass:
17352	case Expr::ObjCSubscriptRefExprClass:
17353	case Expr::ObjCIsaExprClass:
17354	case Expr::ObjCAvailabilityCheckExprClass:
17355	case Expr::ShuffleVectorExprClass:
17356	case Expr::ConvertVectorExprClass:
17357	case Expr::BlockExprClass:
17358	case Expr::NoStmtClass:
17359	case Expr::OpaqueValueExprClass:
17360	case Expr::PackExpansionExprClass:
17361	case Expr::SubstNonTypeTemplateParmPackExprClass:
17362	case Expr::FunctionParmPackExprClass:
17363	case Expr::AsTypeExprClass:
17364	case Expr::ObjCIndirectCopyRestoreExprClass:
17365	case Expr::MaterializeTemporaryExprClass:
17366	case Expr::PseudoObjectExprClass:
17367	case Expr::AtomicExprClass:
17368	case Expr::LambdaExprClass:
17369	case Expr::CXXFoldExprClass:
17370	case Expr::CoawaitExprClass:
17371	case Expr::DependentCoawaitExprClass:
17372	case Expr::CoyieldExprClass:
17373	case Expr::SYCLUniqueStableNameExprClass:
17374	case Expr::CXXParenListInitExprClass:
17375	case Expr::HLSLOutArgExprClass:
17376	return ICEDiag(IK_NotICE, E->getBeginLoc());
17377
17378	case Expr::InitListExprClass: {
17379	// C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the
17380	// form "T x = { a };" is equivalent to "T x = a;".
17381	// Unless we're initializing a reference, T is a scalar as it is known to be
17382	// of integral or enumeration type.
17383	if (E->isPRValue())
17384	if (cast<InitListExpr>(E)->getNumInits() == 1)
17385	return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx);
17386	return ICEDiag(IK_NotICE, E->getBeginLoc());
17387	}
17388
17389	case Expr::SizeOfPackExprClass:
17390	case Expr::GNUNullExprClass:
17391	case Expr::SourceLocExprClass:
17392	case Expr::EmbedExprClass:
17393	case Expr::OpenACCAsteriskSizeExprClass:
17394	return NoDiag();
17395
17396	case Expr::PackIndexingExprClass:
17397	return CheckICE(cast<PackIndexingExpr>(E)->getSelectedExpr(), Ctx);
17398
17399	case Expr::SubstNonTypeTemplateParmExprClass:
17400	return
17401	CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx);
17402
17403	case Expr::ConstantExprClass:
17404	return CheckICE(cast<ConstantExpr>(E)->getSubExpr(), Ctx);
17405
17406	case Expr::ParenExprClass:
17407	return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx);
17408	case Expr::GenericSelectionExprClass:
17409	return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx);
17410	case Expr::IntegerLiteralClass:
17411	case Expr::FixedPointLiteralClass:
17412	case Expr::CharacterLiteralClass:
17413	case Expr::ObjCBoolLiteralExprClass:
17414	case Expr::CXXBoolLiteralExprClass:
17415	case Expr::CXXScalarValueInitExprClass:
17416	case Expr::TypeTraitExprClass:
17417	case Expr::ConceptSpecializationExprClass:
17418	case Expr::RequiresExprClass:
17419	case Expr::ArrayTypeTraitExprClass:
17420	case Expr::ExpressionTraitExprClass:
17421	case Expr::CXXNoexceptExprClass:
17422	return NoDiag();
17423	case Expr::CallExprClass:
17424	case Expr::CXXOperatorCallExprClass: {
17425	// C99 6.6/3 allows function calls within unevaluated subexpressions of
17426	// constant expressions, but they can never be ICEs because an ICE cannot
17427	// contain an operand of (pointer to) function type.
17428	const CallExpr *CE = cast<CallExpr>(E);
17429	if (CE->getBuiltinCallee())
17430	return CheckEvalInICE(E, Ctx);
17431	return ICEDiag(IK_NotICE, E->getBeginLoc());
17432	}
17433	case Expr::CXXRewrittenBinaryOperatorClass:
17434	return CheckICE(cast<CXXRewrittenBinaryOperator>(E)->getSemanticForm(),
17435	Ctx);
17436	case Expr::DeclRefExprClass: {
17437	const NamedDecl *D = cast<DeclRefExpr>(E)->getDecl();
17438	if (isa<EnumConstantDecl>(D))
17439	return NoDiag();
17440
17441	// C++ and OpenCL (FIXME: spec reference?) allow reading const-qualified
17442	// integer variables in constant expressions:
17443	//
17444	// C++ 7.1.5.1p2
17445	// A variable of non-volatile const-qualified integral or enumeration
17446	// type initialized by an ICE can be used in ICEs.
17447	//
17448	// We sometimes use CheckICE to check the C++98 rules in C++11 mode. In
17449	// that mode, use of reference variables should not be allowed.
17450	const VarDecl *VD = dyn_cast<VarDecl>(D);
17451	if (VD && VD->isUsableInConstantExpressions(C: Ctx) &&
17452	!VD->getType()->isReferenceType())
17453	return NoDiag();
17454
17455	return ICEDiag(IK_NotICE, E->getBeginLoc());
17456	}
17457	case Expr::UnaryOperatorClass: {
17458	const UnaryOperator *Exp = cast<UnaryOperator>(E);
17459	switch (Exp->getOpcode()) {
17460	case UO_PostInc:
17461	case UO_PostDec:
17462	case UO_PreInc:
17463	case UO_PreDec:
17464	case UO_AddrOf:
17465	case UO_Deref:
17466	case UO_Coawait:
17467	// C99 6.6/3 allows increment and decrement within unevaluated
17468	// subexpressions of constant expressions, but they can never be ICEs
17469	// because an ICE cannot contain an lvalue operand.
17470	return ICEDiag(IK_NotICE, E->getBeginLoc());
17471	case UO_Extension:
17472	case UO_LNot:
17473	case UO_Plus:
17474	case UO_Minus:
17475	case UO_Not:
17476	case UO_Real:
17477	case UO_Imag:
17478	return CheckICE(E: Exp->getSubExpr(), Ctx);
17479	}
17480	llvm_unreachable("invalid unary operator class");
17481	}
17482	case Expr::OffsetOfExprClass: {
17483	// Note that per C99, offsetof must be an ICE. And AFAIK, using
17484	// EvaluateAsRValue matches the proposed gcc behavior for cases like
17485	// "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect
17486	// compliance: we should warn earlier for offsetof expressions with
17487	// array subscripts that aren't ICEs, and if the array subscripts
17488	// are ICEs, the value of the offsetof must be an integer constant.
17489	return CheckEvalInICE(E, Ctx);
17490	}
17491	case Expr::UnaryExprOrTypeTraitExprClass: {
17492	const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E);
17493	if ((Exp->getKind() == UETT_SizeOf) &&
17494	Exp->getTypeOfArgument()->isVariableArrayType())
17495	return ICEDiag(IK_NotICE, E->getBeginLoc());
17496	if (Exp->getKind() == UETT_CountOf) {
17497	QualType ArgTy = Exp->getTypeOfArgument();
17498	if (ArgTy->isVariableArrayType()) {
17499	// We need to look whether the array is multidimensional. If it is,
17500	// then we want to check the size expression manually to see whether
17501	// it is an ICE or not.
17502	const auto *VAT = Ctx.getAsVariableArrayType(T: ArgTy);
17503	if (VAT->getElementType()->isArrayType())
17504	return CheckICE(VAT->getSizeExpr(), Ctx);
17505
17506	// Otherwise, this is a regular VLA, which is definitely not an ICE.
17507	return ICEDiag(IK_NotICE, E->getBeginLoc());
17508	}
17509	}
17510	return NoDiag();
17511	}
17512	case Expr::BinaryOperatorClass: {
17513	const BinaryOperator *Exp = cast<BinaryOperator>(E);
17514	switch (Exp->getOpcode()) {
17515	case BO_PtrMemD:
17516	case BO_PtrMemI:
17517	case BO_Assign:
17518	case BO_MulAssign:
17519	case BO_DivAssign:
17520	case BO_RemAssign:
17521	case BO_AddAssign:
17522	case BO_SubAssign:
17523	case BO_ShlAssign:
17524	case BO_ShrAssign:
17525	case BO_AndAssign:
17526	case BO_XorAssign:
17527	case BO_OrAssign:
17528	// C99 6.6/3 allows assignments within unevaluated subexpressions of
17529	// constant expressions, but they can never be ICEs because an ICE cannot
17530	// contain an lvalue operand.
17531	return ICEDiag(IK_NotICE, E->getBeginLoc());
17532
17533	case BO_Mul:
17534	case BO_Div:
17535	case BO_Rem:
17536	case BO_Add:
17537	case BO_Sub:
17538	case BO_Shl:
17539	case BO_Shr:
17540	case BO_LT:
17541	case BO_GT:
17542	case BO_LE:
17543	case BO_GE:
17544	case BO_EQ:
17545	case BO_NE:
17546	case BO_And:
17547	case BO_Xor:
17548	case BO_Or:
17549	case BO_Comma:
17550	case BO_Cmp: {
17551	ICEDiag LHSResult = CheckICE(E: Exp->getLHS(), Ctx);
17552	ICEDiag RHSResult = CheckICE(E: Exp->getRHS(), Ctx);
17553	if (Exp->getOpcode() == BO_Div ||
17554	Exp->getOpcode() == BO_Rem) {
17555	// EvaluateAsRValue gives an error for undefined Div/Rem, so make sure
17556	// we don't evaluate one.
17557	if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) {
17558	llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx);
17559	if (REval == 0)
17560	return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
17561	if (REval.isSigned() && REval.isAllOnes()) {
17562	llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx);
17563	if (LEval.isMinSignedValue())
17564	return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
17565	}
17566	}
17567	}
17568	if (Exp->getOpcode() == BO_Comma) {
17569	if (Ctx.getLangOpts().C99) {
17570	// C99 6.6p3 introduces a strange edge case: comma can be in an ICE
17571	// if it isn't evaluated.
17572	if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE)
17573	return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
17574	} else {
17575	// In both C89 and C++, commas in ICEs are illegal.
17576	return ICEDiag(IK_NotICE, E->getBeginLoc());
17577	}
17578	}
17579	return Worst(A: LHSResult, B: RHSResult);
17580	}
17581	case BO_LAnd:
17582	case BO_LOr: {
17583	ICEDiag LHSResult = CheckICE(E: Exp->getLHS(), Ctx);
17584	ICEDiag RHSResult = CheckICE(E: Exp->getRHS(), Ctx);
17585	if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) {
17586	// Rare case where the RHS has a comma "side-effect"; we need
17587	// to actually check the condition to see whether the side
17588	// with the comma is evaluated.
17589	if ((Exp->getOpcode() == BO_LAnd) !=
17590	(Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0))
17591	return RHSResult;
17592	return NoDiag();
17593	}
17594
17595	return Worst(A: LHSResult, B: RHSResult);
17596	}
17597	}
17598	llvm_unreachable("invalid binary operator kind");
17599	}
17600	case Expr::ImplicitCastExprClass:
17601	case Expr::CStyleCastExprClass:
17602	case Expr::CXXFunctionalCastExprClass:
17603	case Expr::CXXStaticCastExprClass:
17604	case Expr::CXXReinterpretCastExprClass:
17605	case Expr::CXXConstCastExprClass:
17606	case Expr::ObjCBridgedCastExprClass: {
17607	const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr();
17608	if (isa<ExplicitCastExpr>(E)) {
17609	if (const FloatingLiteral *FL
17610	= dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) {
17611	unsigned DestWidth = Ctx.getIntWidth(T: E->getType());
17612	bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType();
17613	APSInt IgnoredVal(DestWidth, !DestSigned);
17614	bool Ignored;
17615	// If the value does not fit in the destination type, the behavior is
17616	// undefined, so we are not required to treat it as a constant
17617	// expression.
17618	if (FL->getValue().convertToInteger(Result&: IgnoredVal,
17619	RM: llvm::APFloat::rmTowardZero,
17620	IsExact: &Ignored) & APFloat::opInvalidOp)
17621	return ICEDiag(IK_NotICE, E->getBeginLoc());
17622	return NoDiag();
17623	}
17624	}
17625	switch (cast<CastExpr>(E)->getCastKind()) {
17626	case CK_LValueToRValue:
17627	case CK_AtomicToNonAtomic:
17628	case CK_NonAtomicToAtomic:
17629	case CK_NoOp:
17630	case CK_IntegralToBoolean:
17631	case CK_IntegralCast:
17632	return CheckICE(E: SubExpr, Ctx);
17633	default:
17634	return ICEDiag(IK_NotICE, E->getBeginLoc());
17635	}
17636	}
17637	case Expr::BinaryConditionalOperatorClass: {
17638	const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E);
17639	ICEDiag CommonResult = CheckICE(E: Exp->getCommon(), Ctx);
17640	if (CommonResult.Kind == IK_NotICE) return CommonResult;
17641	ICEDiag FalseResult = CheckICE(E: Exp->getFalseExpr(), Ctx);
17642	if (FalseResult.Kind == IK_NotICE) return FalseResult;
17643	if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult;
17644	if (FalseResult.Kind == IK_ICEIfUnevaluated &&
17645	Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag();
17646	return FalseResult;
17647	}
17648	case Expr::ConditionalOperatorClass: {
17649	const ConditionalOperator *Exp = cast<ConditionalOperator>(E);
17650	// If the condition (ignoring parens) is a __builtin_constant_p call,
17651	// then only the true side is actually considered in an integer constant
17652	// expression, and it is fully evaluated. This is an important GNU
17653	// extension. See GCC PR38377 for discussion.
17654	if (const CallExpr *CallCE
17655	= dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts()))
17656	if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
17657	return CheckEvalInICE(E, Ctx);
17658	ICEDiag CondResult = CheckICE(E: Exp->getCond(), Ctx);
17659	if (CondResult.Kind == IK_NotICE)
17660	return CondResult;
17661
17662	ICEDiag TrueResult = CheckICE(E: Exp->getTrueExpr(), Ctx);
17663	ICEDiag FalseResult = CheckICE(E: Exp->getFalseExpr(), Ctx);
17664
17665	if (TrueResult.Kind == IK_NotICE)
17666	return TrueResult;
17667	if (FalseResult.Kind == IK_NotICE)
17668	return FalseResult;
17669	if (CondResult.Kind == IK_ICEIfUnevaluated)
17670	return CondResult;
17671	if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE)
17672	return NoDiag();
17673	// Rare case where the diagnostics depend on which side is evaluated
17674	// Note that if we get here, CondResult is 0, and at least one of
17675	// TrueResult and FalseResult is non-zero.
17676	if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0)
17677	return FalseResult;
17678	return TrueResult;
17679	}
17680	case Expr::CXXDefaultArgExprClass:
17681	return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx);
17682	case Expr::CXXDefaultInitExprClass:
17683	return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx);
17684	case Expr::ChooseExprClass: {
17685	return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx);
17686	}
17687	case Expr::BuiltinBitCastExprClass: {
17688	if (!checkBitCastConstexprEligibility(nullptr, Ctx, cast<CastExpr>(E)))
17689	return ICEDiag(IK_NotICE, E->getBeginLoc());
17690	return CheckICE(cast<CastExpr>(E)->getSubExpr(), Ctx);
17691	}
17692	}
17693
17694	llvm_unreachable("Invalid StmtClass!");
17695	}
17696
17697	/// Evaluate an expression as a C++11 integral constant expression.
17698	static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx,
17699	const Expr *E,
17700	llvm::APSInt *Value,
17701	SourceLocation *Loc) {
17702	if (!E->getType()->isIntegralOrUnscopedEnumerationType()) {
17703	if (Loc) *Loc = E->getExprLoc();
17704	return false;
17705	}
17706
17707	APValue Result;
17708	if (!E->isCXX11ConstantExpr(Ctx, Result: &Result, Loc))
17709	return false;
17710
17711	if (!Result.isInt()) {
17712	if (Loc) *Loc = E->getExprLoc();
17713	return false;
17714	}
17715
17716	if (Value) *Value = Result.getInt();
17717	return true;
17718	}
17719
17720	bool Expr::isIntegerConstantExpr(const ASTContext &Ctx,
17721	SourceLocation *Loc) const {
17722	assert(!isValueDependent() &&
17723	"Expression evaluator can't be called on a dependent expression.");
17724
17725	ExprTimeTraceScope TimeScope(this, Ctx, "isIntegerConstantExpr");
17726
17727	if (Ctx.getLangOpts().CPlusPlus11)
17728	return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, E: this, Value: nullptr, Loc);
17729
17730	ICEDiag D = CheckICE(E: this, Ctx);
17731	if (D.Kind != IK_ICE) {
17732	if (Loc) *Loc = D.Loc;
17733	return false;
17734	}
17735	return true;
17736	}
17737
17738	std::optional<llvm::APSInt>
17739	Expr::getIntegerConstantExpr(const ASTContext &Ctx, SourceLocation *Loc) const {
17740	if (isValueDependent()) {
17741	// Expression evaluator can't succeed on a dependent expression.
17742	return std::nullopt;
17743	}
17744
17745	APSInt Value;
17746
17747	if (Ctx.getLangOpts().CPlusPlus11) {
17748	if (EvaluateCPlusPlus11IntegralConstantExpr(Ctx, E: this, Value: &Value, Loc))
17749	return Value;
17750	return std::nullopt;
17751	}
17752
17753	if (!isIntegerConstantExpr(Ctx, Loc))
17754	return std::nullopt;
17755
17756	// The only possible side-effects here are due to UB discovered in the
17757	// evaluation (for instance, INT_MAX + 1). In such a case, we are still
17758	// required to treat the expression as an ICE, so we produce the folded
17759	// value.
17760	EvalResult ExprResult;
17761	Expr::EvalStatus Status;
17762	EvalInfo Info(Ctx, Status, EvalInfo::EM_IgnoreSideEffects);
17763	Info.InConstantContext = true;
17764
17765	if (!::EvaluateAsInt(E: this, ExprResult, Ctx, AllowSideEffects: SE_AllowSideEffects, Info))
17766	llvm_unreachable("ICE cannot be evaluated!");
17767
17768	return ExprResult.Val.getInt();
17769	}
17770
17771	bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const {
17772	assert(!isValueDependent() &&
17773	"Expression evaluator can't be called on a dependent expression.");
17774
17775	return CheckICE(E: this, Ctx).Kind == IK_ICE;
17776	}
17777
17778	bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result,
17779	SourceLocation *Loc) const {
17780	assert(!isValueDependent() &&
17781	"Expression evaluator can't be called on a dependent expression.");
17782
17783	// We support this checking in C++98 mode in order to diagnose compatibility
17784	// issues.
17785	assert(Ctx.getLangOpts().CPlusPlus);
17786
17787	// Build evaluation settings.
17788	Expr::EvalStatus Status;
17789	SmallVector<PartialDiagnosticAt, 8> Diags;
17790	Status.Diag = &Diags;
17791	EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
17792
17793	APValue Scratch;
17794	bool IsConstExpr =
17795	::EvaluateAsRValue(Info, E: this, Result&: Result ? *Result : Scratch) &&
17796	// FIXME: We don't produce a diagnostic for this, but the callers that
17797	// call us on arbitrary full-expressions should generally not care.
17798	Info.discardCleanups() && !Status.HasSideEffects;
17799
17800	if (!Diags.empty()) {
17801	IsConstExpr = false;
17802	if (Loc) *Loc = Diags[0].first;
17803	} else if (!IsConstExpr) {
17804	// FIXME: This shouldn't happen.
17805	if (Loc) *Loc = getExprLoc();
17806	}
17807
17808	return IsConstExpr;
17809	}
17810
17811	bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
17812	const FunctionDecl *Callee,
17813	ArrayRef<const Expr*> Args,
17814	const Expr *This) const {
17815	assert(!isValueDependent() &&
17816	"Expression evaluator can't be called on a dependent expression.");
17817
17818	llvm::TimeTraceScope TimeScope("EvaluateWithSubstitution", [&] {
17819	std::string Name;
17820	llvm::raw_string_ostream OS(Name);
17821	Callee->getNameForDiagnostic(OS, Policy: Ctx.getPrintingPolicy(),
17822	/*Qualified=*/true);
17823	return Name;
17824	});
17825
17826	Expr::EvalStatus Status;
17827	EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated);
17828	Info.InConstantContext = true;
17829
17830	LValue ThisVal;
17831	const LValue *ThisPtr = nullptr;
17832	if (This) {
17833	#ifndef NDEBUG
17834	auto *MD = dyn_cast<CXXMethodDecl>(Val: Callee);
17835	assert(MD && "Don't provide `this` for non-methods.");
17836	assert(MD->isImplicitObjectMemberFunction() &&
17837	"Don't provide `this` for methods without an implicit object.");
17838	#endif
17839	if (!This->isValueDependent() &&
17840	EvaluateObjectArgument(Info, Object: This, This&: ThisVal) &&
17841	!Info.EvalStatus.HasSideEffects)
17842	ThisPtr = &ThisVal;
17843
17844	// Ignore any side-effects from a failed evaluation. This is safe because
17845	// they can't interfere with any other argument evaluation.
17846	Info.EvalStatus.HasSideEffects = false;
17847	}
17848
17849	CallRef Call = Info.CurrentCall->createCall(Callee);
17850	for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
17851	I != E; ++I) {
17852	unsigned Idx = I - Args.begin();
17853	if (Idx >= Callee->getNumParams())
17854	break;
17855	const ParmVarDecl *PVD = Callee->getParamDecl(i: Idx);
17856	if ((*I)->isValueDependent() ||
17857	!EvaluateCallArg(PVD, Arg: *I, Call, Info) ||
17858	Info.EvalStatus.HasSideEffects) {
17859	// If evaluation fails, throw away the argument entirely.
17860	if (APValue *Slot = Info.getParamSlot(Call, PVD))
17861	*Slot = APValue();
17862	}
17863
17864	// Ignore any side-effects from a failed evaluation. This is safe because
17865	// they can't interfere with any other argument evaluation.
17866	Info.EvalStatus.HasSideEffects = false;
17867	}
17868
17869	// Parameter cleanups happen in the caller and are not part of this
17870	// evaluation.
17871	Info.discardCleanups();
17872	Info.EvalStatus.HasSideEffects = false;
17873
17874	// Build fake call to Callee.
17875	CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr, This,
17876	Call);
17877	// FIXME: Missing ExprWithCleanups in enable_if conditions?
17878	FullExpressionRAII Scope(Info);
17879	return Evaluate(Result&: Value, Info, E: this) && Scope.destroy() &&
17880	!Info.EvalStatus.HasSideEffects;
17881	}
17882
17883	bool Expr::isPotentialConstantExpr(const FunctionDecl *FD,
17884	SmallVectorImpl<
17885	PartialDiagnosticAt> &Diags) {
17886	// FIXME: It would be useful to check constexpr function templates, but at the
17887	// moment the constant expression evaluator cannot cope with the non-rigorous
17888	// ASTs which we build for dependent expressions.
17889	if (FD->isDependentContext())
17890	return true;
17891
17892	llvm::TimeTraceScope TimeScope("isPotentialConstantExpr", [&] {
17893	std::string Name;
17894	llvm::raw_string_ostream OS(Name);
17895	FD->getNameForDiagnostic(OS, Policy: FD->getASTContext().getPrintingPolicy(),
17896	/*Qualified=*/true);
17897	return Name;
17898	});
17899
17900	Expr::EvalStatus Status;
17901	Status.Diag = &Diags;
17902
17903	EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_ConstantExpression);
17904	Info.InConstantContext = true;
17905	Info.CheckingPotentialConstantExpression = true;
17906
17907	// The constexpr VM attempts to compile all methods to bytecode here.
17908	if (Info.EnableNewConstInterp) {
17909	Info.Ctx.getInterpContext().isPotentialConstantExpr(Parent&: Info, FnDecl: FD);
17910	return Diags.empty();
17911	}
17912
17913	const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Val: FD);
17914	const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr;
17915
17916	// Fabricate an arbitrary expression on the stack and pretend that it
17917	// is a temporary being used as the 'this' pointer.
17918	LValue This;
17919	ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy);
17920	This.set({&VIE, Info.CurrentCall->Index});
17921
17922	ArrayRef<const Expr*> Args;
17923
17924	APValue Scratch;
17925	if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(Val: FD)) {
17926	// Evaluate the call as a constant initializer, to allow the construction
17927	// of objects of non-literal types.
17928	Info.setEvaluatingDecl(Base: This.getLValueBase(), Value&: Scratch);
17929	HandleConstructorCall(&VIE, This, Args, CD, Info, Scratch);
17930	} else {
17931	SourceLocation Loc = FD->getLocation();
17932	HandleFunctionCall(
17933	Loc, FD, (MD && MD->isImplicitObjectMemberFunction()) ? &This : nullptr,
17934	&VIE, Args, CallRef(), FD->getBody(), Info, Scratch,
17935	/*ResultSlot=*/nullptr);
17936	}
17937
17938	return Diags.empty();
17939	}
17940
17941	bool Expr::isPotentialConstantExprUnevaluated(Expr *E,
17942	const FunctionDecl *FD,
17943	SmallVectorImpl<
17944	PartialDiagnosticAt> &Diags) {
17945	assert(!E->isValueDependent() &&
17946	"Expression evaluator can't be called on a dependent expression.");
17947
17948	Expr::EvalStatus Status;
17949	Status.Diag = &Diags;
17950
17951	EvalInfo Info(FD->getASTContext(), Status,
17952	EvalInfo::EM_ConstantExpressionUnevaluated);
17953	Info.InConstantContext = true;
17954	Info.CheckingPotentialConstantExpression = true;
17955
17956	// Fabricate a call stack frame to give the arguments a plausible cover story.
17957	CallStackFrame Frame(Info, SourceLocation(), FD, /*This=*/nullptr,
17958	/*CallExpr=*/nullptr, CallRef());
17959
17960	APValue ResultScratch;
17961	Evaluate(Result&: ResultScratch, Info, E);
17962	return Diags.empty();
17963	}
17964
17965	bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx,
17966	unsigned Type) const {
17967	if (!getType()->isPointerType())
17968	return false;
17969
17970	Expr::EvalStatus Status;
17971	EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
17972	return tryEvaluateBuiltinObjectSize(E: this, Type, Info, Size&: Result);
17973	}
17974
17975	static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
17976	EvalInfo &Info, std::string *StringResult) {
17977	if (!E->getType()->hasPointerRepresentation() || !E->isPRValue())
17978	return false;
17979
17980	LValue String;
17981
17982	if (!EvaluatePointer(E, Result&: String, Info))
17983	return false;
17984
17985	QualType CharTy = E->getType()->getPointeeType();
17986
17987	// Fast path: if it's a string literal, search the string value.
17988	if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>(
17989	Val: String.getLValueBase().dyn_cast<const Expr *>())) {
17990	StringRef Str = S->getBytes();
17991	int64_t Off = String.Offset.getQuantity();
17992	if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() &&
17993	S->getCharByteWidth() == 1 &&
17994	// FIXME: Add fast-path for wchar_t too.
17995	Info.Ctx.hasSameUnqualifiedType(T1: CharTy, T2: Info.Ctx.CharTy)) {
17996	Str = Str.substr(Start: Off);
17997
17998	StringRef::size_type Pos = Str.find(C: 0);
17999	if (Pos != StringRef::npos)
18000	Str = Str.substr(Start: 0, N: Pos);
18001
18002	Result = Str.size();
18003	if (StringResult)
18004	*StringResult = Str;
18005	return true;
18006	}
18007
18008	// Fall through to slow path.
18009	}
18010
18011	// Slow path: scan the bytes of the string looking for the terminating 0.
18012	for (uint64_t Strlen = 0; /**/; ++Strlen) {
18013	APValue Char;
18014	if (!handleLValueToRValueConversion(Info, Conv: E, Type: CharTy, LVal: String, RVal&: Char) ||
18015	!Char.isInt())
18016	return false;
18017	if (!Char.getInt()) {
18018	Result = Strlen;
18019	return true;
18020	} else if (StringResult)
18021	StringResult->push_back(c: Char.getInt().getExtValue());
18022	if (!HandleLValueArrayAdjustment(Info, E, LVal&: String, EltTy: CharTy, Adjustment: 1))
18023	return false;
18024	}
18025	}
18026
18027	std::optional<std::string> Expr::tryEvaluateString(ASTContext &Ctx) const {
18028	Expr::EvalStatus Status;
18029	EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
18030	uint64_t Result;
18031	std::string StringResult;
18032
18033	if (EvaluateBuiltinStrLen(E: this, Result, Info, StringResult: &StringResult))
18034	return StringResult;
18035	return {};
18036	}
18037
18038	template <typename T>
18039	static bool EvaluateCharRangeAsStringImpl(const Expr *, T &Result,
18040	const Expr *SizeExpression,
18041	const Expr *PtrExpression,
18042	ASTContext &Ctx,
18043	Expr::EvalResult &Status) {
18044	EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
18045	Info.InConstantContext = true;
18046
18047	if (Info.EnableNewConstInterp)
18048	return Info.Ctx.getInterpContext().evaluateCharRange(Info, SizeExpression,
18049	PtrExpression, Result);
18050
18051	LValue String;
18052	FullExpressionRAII Scope(Info);
18053	APSInt SizeValue;
18054	if (!::EvaluateInteger(E: SizeExpression, Result&: SizeValue, Info))
18055	return false;
18056
18057	uint64_t Size = SizeValue.getZExtValue();
18058
18059	// FIXME: better protect against invalid or excessive sizes
18060	if constexpr (std::is_same_v<APValue, T>)
18061	Result = APValue(APValue::UninitArray{}, Size, Size);
18062	else {
18063	if (Size < Result.max_size())
18064	Result.reserve(Size);
18065	}
18066	if (!::EvaluatePointer(E: PtrExpression, Result&: String, Info))
18067	return false;
18068
18069	QualType CharTy = PtrExpression->getType()->getPointeeType();
18070	for (uint64_t I = 0; I < Size; ++I) {
18071	APValue Char;
18072	if (!handleLValueToRValueConversion(Info, Conv: PtrExpression, Type: CharTy, LVal: String,
18073	RVal&: Char))
18074	return false;
18075
18076	if constexpr (std::is_same_v<APValue, T>) {
18077	Result.getArrayInitializedElt(I) = std::move(Char);
18078	} else {
18079	APSInt C = Char.getInt();
18080
18081	assert(C.getBitWidth() <= 8 &&
18082	"string element not representable in char");
18083
18084	Result.push_back(static_cast<char>(C.getExtValue()));
18085	}
18086
18087	if (!HandleLValueArrayAdjustment(Info, E: PtrExpression, LVal&: String, EltTy: CharTy, Adjustment: 1))
18088	return false;
18089	}
18090
18091	return Scope.destroy() && CheckMemoryLeaks(Info);
18092	}
18093
18094	bool Expr::EvaluateCharRangeAsString(std::string &Result,
18095	const Expr *SizeExpression,
18096	const Expr *PtrExpression, ASTContext &Ctx,
18097	EvalResult &Status) const {
18098	return EvaluateCharRangeAsStringImpl(this, Result, SizeExpression,
18099	PtrExpression, Ctx, Status);
18100	}
18101
18102	bool Expr::EvaluateCharRangeAsString(APValue &Result,
18103	const Expr *SizeExpression,
18104	const Expr *PtrExpression, ASTContext &Ctx,
18105	EvalResult &Status) const {
18106	return EvaluateCharRangeAsStringImpl(this, Result, SizeExpression,
18107	PtrExpression, Ctx, Status);
18108	}
18109
18110	bool Expr::tryEvaluateStrLen(uint64_t &Result, ASTContext &Ctx) const {
18111	Expr::EvalStatus Status;
18112	EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
18113	return EvaluateBuiltinStrLen(E: this, Result, Info);
18114	}
18115
18116	namespace {
18117	struct IsWithinLifetimeHandler {
18118	EvalInfo &Info;
18119	static constexpr AccessKinds AccessKind = AccessKinds::AK_IsWithinLifetime;
18120	using result_type = std::optional<bool>;
18121	std::optional<bool> failed() { return std::nullopt; }
18122	template <typename T>
18123	std::optional<bool> found(T &Subobj, QualType SubobjType) {
18124	return true;
18125	}
18126	};
18127
18128	std::optional<bool> EvaluateBuiltinIsWithinLifetime(IntExprEvaluator &IEE,
18129	const CallExpr *E) {
18130	EvalInfo &Info = IEE.Info;
18131	// Sometimes this is called during some sorts of constant folding / early
18132	// evaluation. These are meant for non-constant expressions and are not
18133	// necessary since this consteval builtin will never be evaluated at runtime.
18134	// Just fail to evaluate when not in a constant context.
18135	if (!Info.InConstantContext)
18136	return std::nullopt;
18137	assert(E->getBuiltinCallee() == Builtin::BI__builtin_is_within_lifetime);
18138	const Expr *Arg = E->getArg(Arg: 0);
18139	if (Arg->isValueDependent())
18140	return std::nullopt;
18141	LValue Val;
18142	if (!EvaluatePointer(E: Arg, Result&: Val, Info))
18143	return std::nullopt;
18144
18145	if (Val.allowConstexprUnknown())
18146	return true;
18147
18148	auto Error = [&](int Diag) {
18149	bool CalledFromStd = false;
18150	const auto *Callee = Info.CurrentCall->getCallee();
18151	if (Callee && Callee->isInStdNamespace()) {
18152	const IdentifierInfo *Identifier = Callee->getIdentifier();
18153	CalledFromStd = Identifier && Identifier->isStr(Str: "is_within_lifetime");
18154	}
18155	Info.CCEDiag(CalledFromStd ? Info.CurrentCall->getCallRange().getBegin()
18156	: E->getExprLoc(),
18157	diag::err_invalid_is_within_lifetime)
18158	<< (CalledFromStd ? "std::is_within_lifetime"
18159	: "__builtin_is_within_lifetime")
18160	<< Diag;
18161	return std::nullopt;
18162	};
18163	// C++2c [meta.const.eval]p4:
18164	// During the evaluation of an expression E as a core constant expression, a
18165	// call to this function is ill-formed unless p points to an object that is
18166	// usable in constant expressions or whose complete object's lifetime began
18167	// within E.
18168
18169	// Make sure it points to an object
18170	// nullptr does not point to an object
18171	if (Val.isNullPointer() || Val.getLValueBase().isNull())
18172	return Error(0);
18173	QualType T = Val.getLValueBase().getType();
18174	assert(!T->isFunctionType() &&
18175	"Pointers to functions should have been typed as function pointers "
18176	"which would have been rejected earlier");
18177	assert(T->isObjectType());
18178	// Hypothetical array element is not an object
18179	if (Val.getLValueDesignator().isOnePastTheEnd())
18180	return Error(1);
18181	assert(Val.getLValueDesignator().isValidSubobject() &&
18182	"Unchecked case for valid subobject");
18183	// All other ill-formed values should have failed EvaluatePointer, so the
18184	// object should be a pointer to an object that is usable in a constant
18185	// expression or whose complete lifetime began within the expression
18186	CompleteObject CO =
18187	findCompleteObject(Info, E, AccessKinds::AK_IsWithinLifetime, Val, T);
18188	// The lifetime hasn't begun yet if we are still evaluating the
18189	// initializer ([basic.life]p(1.2))
18190	if (Info.EvaluatingDeclValue && CO.Value == Info.EvaluatingDeclValue)
18191	return Error(2);
18192
18193	if (!CO)
18194	return false;
18195	IsWithinLifetimeHandler handler{.Info: Info};
18196	return findSubobject(Info, E, CO, Val.getLValueDesignator(), handler);
18197	}
18198	} // namespace
18199