1//===-- InstructionSimplify.h - Fold instrs into simpler forms --*- C++ -*-===//
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 declares routines for folding instructions into simpler forms
10// that do not require creating new instructions. This does constant folding
11// ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
12// returning a constant ("and i32 %x, 0" -> "0") or an already existing value
13// ("and i32 %x, %x" -> "%x"). If the simplification is also an instruction
14// then it dominates the original instruction.
15//
16// These routines implicitly resolve undef uses. The easiest way to be safe when
17// using these routines to obtain simplified values for existing instructions is
18// to always replace all uses of the instructions with the resulting simplified
19// values. This will prevent other code from seeing the same undef uses and
20// resolving them to different values.
21//
22// They require that all the IR that they encounter be valid and inserted into a
23// parent function.
24//
25// Additionally, these routines can't simplify to the instructions that are not
26// def-reachable, meaning we can't just scan the basic block for instructions
27// to simplify to.
28//
29//===----------------------------------------------------------------------===//
30
31#ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
32#define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
33
34#include "llvm/Analysis/SimplifyQuery.h"
35#include "llvm/IR/FPEnv.h"
36
37namespace llvm {
38
39template <typename T, typename... TArgs> class AnalysisManager;
40template <class T> class ArrayRef;
41class AssumptionCache;
42class BinaryOperator;
43class CallBase;
44class DataLayout;
45class DominatorTree;
46class Function;
47class Instruction;
48class LoadInst;
49struct LoopStandardAnalysisResults;
50class Pass;
51template <class T, unsigned n> class SmallSetVector;
52class TargetLibraryInfo;
53class Type;
54class Value;
55
56// NOTE: the explicit multiple argument versions of these functions are
57// deprecated.
58// Please use the SimplifyQuery versions in new code.
59
60/// Given operands for an Add, fold the result or return null.
61Value *simplifyAddInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW,
62 const SimplifyQuery &Q);
63
64/// Given operands for a Sub, fold the result or return null.
65Value *simplifySubInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW,
66 const SimplifyQuery &Q);
67
68/// Given operands for a Mul, fold the result or return null.
69Value *simplifyMulInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW,
70 const SimplifyQuery &Q);
71
72/// Given operands for an SDiv, fold the result or return null.
73Value *simplifySDivInst(Value *LHS, Value *RHS, bool IsExact,
74 const SimplifyQuery &Q);
75
76/// Given operands for a UDiv, fold the result or return null.
77Value *simplifyUDivInst(Value *LHS, Value *RHS, bool IsExact,
78 const SimplifyQuery &Q);
79
80/// Given operands for an SRem, fold the result or return null.
81Value *simplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
82
83/// Given operands for a URem, fold the result or return null.
84Value *simplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
85
86/// Given operand for an FNeg, fold the result or return null.
87Value *simplifyFNegInst(Value *Op, FastMathFlags FMF, const SimplifyQuery &Q);
88
89
90/// Given operands for an FAdd, fold the result or return null.
91Value *
92simplifyFAddInst(Value *LHS, Value *RHS, FastMathFlags FMF,
93 const SimplifyQuery &Q,
94 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
95 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
96
97/// Given operands for an FSub, fold the result or return null.
98Value *
99simplifyFSubInst(Value *LHS, Value *RHS, FastMathFlags FMF,
100 const SimplifyQuery &Q,
101 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
102 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
103
104/// Given operands for an FMul, fold the result or return null.
105Value *
106simplifyFMulInst(Value *LHS, Value *RHS, FastMathFlags FMF,
107 const SimplifyQuery &Q,
108 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
109 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
110
111/// Given operands for the multiplication of a FMA, fold the result or return
112/// null. In contrast to simplifyFMulInst, this function will not perform
113/// simplifications whose unrounded results differ when rounded to the argument
114/// type.
115Value *simplifyFMAFMul(Value *LHS, Value *RHS, FastMathFlags FMF,
116 const SimplifyQuery &Q,
117 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
118 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
119
120/// Given operands for an FDiv, fold the result or return null.
121Value *
122simplifyFDivInst(Value *LHS, Value *RHS, FastMathFlags FMF,
123 const SimplifyQuery &Q,
124 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
125 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
126
127/// Given operands for an FRem, fold the result or return null.
128Value *
129simplifyFRemInst(Value *LHS, Value *RHS, FastMathFlags FMF,
130 const SimplifyQuery &Q,
131 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
132 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
133
134/// Given operands for a Shl, fold the result or return null.
135Value *simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
136 const SimplifyQuery &Q);
137
138/// Given operands for a LShr, fold the result or return null.
139Value *simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact,
140 const SimplifyQuery &Q);
141
142/// Given operands for a AShr, fold the result or return nulll.
143Value *simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact,
144 const SimplifyQuery &Q);
145
146/// Given operands for an And, fold the result or return null.
147Value *simplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
148
149/// Given operands for an Or, fold the result or return null.
150Value *simplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
151
152/// Given operands for an Xor, fold the result or return null.
153Value *simplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
154
155/// Given operands for an ICmpInst, fold the result or return null.
156Value *simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
157 const SimplifyQuery &Q);
158
159/// Given operands for an FCmpInst, fold the result or return null.
160Value *simplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
161 FastMathFlags FMF, const SimplifyQuery &Q);
162
163/// Given operands for a SelectInst, fold the result or return null.
164Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
165 const SimplifyQuery &Q);
166
167/// Given operands for a GetElementPtrInst, fold the result or return null.
168Value *simplifyGEPInst(Type *SrcTy, Value *Ptr, ArrayRef<Value *> Indices,
169 bool InBounds, const SimplifyQuery &Q);
170
171/// Given operands for an InsertValueInst, fold the result or return null.
172Value *simplifyInsertValueInst(Value *Agg, Value *Val, ArrayRef<unsigned> Idxs,
173 const SimplifyQuery &Q);
174
175/// Given operands for an InsertElement, fold the result or return null.
176Value *simplifyInsertElementInst(Value *Vec, Value *Elt, Value *Idx,
177 const SimplifyQuery &Q);
178
179/// Given operands for an ExtractValueInst, fold the result or return null.
180Value *simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs,
181 const SimplifyQuery &Q);
182
183/// Given operands for an ExtractElementInst, fold the result or return null.
184Value *simplifyExtractElementInst(Value *Vec, Value *Idx,
185 const SimplifyQuery &Q);
186
187/// Given operands for a CastInst, fold the result or return null.
188Value *simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
189 const SimplifyQuery &Q);
190
191/// Given operands for a BinaryIntrinsic, fold the result or return null.
192Value *simplifyBinaryIntrinsic(Intrinsic::ID IID, Type *ReturnType, Value *Op0,
193 Value *Op1, const SimplifyQuery &Q,
194 const CallBase *Call);
195
196/// Given operands for a ShuffleVectorInst, fold the result or return null.
197/// See class ShuffleVectorInst for a description of the mask representation.
198Value *simplifyShuffleVectorInst(Value *Op0, Value *Op1, ArrayRef<int> Mask,
199 Type *RetTy, const SimplifyQuery &Q);
200
201//=== Helper functions for higher up the class hierarchy.
202
203/// Given operands for a CmpInst, fold the result or return null.
204Value *simplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
205 const SimplifyQuery &Q);
206
207/// Given operand for a UnaryOperator, fold the result or return null.
208Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q);
209
210/// Given operand for a UnaryOperator, fold the result or return null.
211/// Try to use FastMathFlags when folding the result.
212Value *simplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF,
213 const SimplifyQuery &Q);
214
215/// Given operands for a BinaryOperator, fold the result or return null.
216Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
217 const SimplifyQuery &Q);
218
219/// Given operands for a BinaryOperator, fold the result or return null.
220/// Try to use FastMathFlags when folding the result.
221Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, FastMathFlags FMF,
222 const SimplifyQuery &Q);
223
224/// Given a callsite, callee, and arguments, fold the result or return null.
225Value *simplifyCall(CallBase *Call, Value *Callee, ArrayRef<Value *> Args,
226 const SimplifyQuery &Q);
227
228/// Given a constrained FP intrinsic call, tries to compute its simplified
229/// version. Returns a simplified result or null.
230///
231/// This function provides an additional contract: it guarantees that if
232/// simplification succeeds that the intrinsic is side effect free. As a result,
233/// successful simplification can be used to delete the intrinsic not just
234/// replace its result.
235Value *simplifyConstrainedFPCall(CallBase *Call, const SimplifyQuery &Q);
236
237/// Given an operand for a Freeze, see if we can fold the result.
238/// If not, this returns null.
239Value *simplifyFreezeInst(Value *Op, const SimplifyQuery &Q);
240
241/// Given a load instruction and its pointer operand, fold the result or return
242/// null.
243Value *simplifyLoadInst(LoadInst *LI, Value *PtrOp, const SimplifyQuery &Q);
244
245/// See if we can compute a simplified version of this instruction. If not,
246/// return null.
247Value *simplifyInstruction(Instruction *I, const SimplifyQuery &Q);
248
249/// Like \p simplifyInstruction but the operands of \p I are replaced with
250/// \p NewOps. Returns a simplified value, or null if none was found.
251Value *
252simplifyInstructionWithOperands(Instruction *I, ArrayRef<Value *> NewOps,
253 const SimplifyQuery &Q);
254
255/// See if V simplifies when its operand Op is replaced with RepOp. If not,
256/// return null.
257/// AllowRefinement specifies whether the simplification can be a refinement
258/// (e.g. 0 instead of poison), or whether it needs to be strictly identical.
259/// Op and RepOp can be assumed to not be poison when determining refinement.
260///
261/// If DropFlags is passed, then the replacement result is only valid if
262/// poison-generating flags/metadata on those instructions are dropped. This
263/// is only useful in conjunction with AllowRefinement=false.
264Value *
265simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
266 const SimplifyQuery &Q, bool AllowRefinement,
267 SmallVectorImpl<Instruction *> *DropFlags = nullptr);
268
269/// Replace all uses of 'I' with 'SimpleV' and simplify the uses recursively.
270///
271/// This first performs a normal RAUW of I with SimpleV. It then recursively
272/// attempts to simplify those users updated by the operation. The 'I'
273/// instruction must not be equal to the simplified value 'SimpleV'.
274/// If UnsimplifiedUsers is provided, instructions that could not be simplified
275/// are added to it.
276///
277/// The function returns true if any simplifications were performed.
278bool replaceAndRecursivelySimplify(
279 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI = nullptr,
280 const DominatorTree *DT = nullptr, AssumptionCache *AC = nullptr,
281 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr);
282
283// These helper functions return a SimplifyQuery structure that contains as
284// many of the optional analysis we use as are currently valid. This is the
285// strongly preferred way of constructing SimplifyQuery in passes.
286const SimplifyQuery getBestSimplifyQuery(Pass &, Function &);
287template <class T, class... TArgs>
288const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &,
289 Function &);
290const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &,
291 const DataLayout &);
292} // end namespace llvm
293
294#endif
295

source code of llvm/include/llvm/Analysis/InstructionSimplify.h