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#include "llvm/Support/Compiler.h"
37
38namespace llvm {
39
40template <typename T, typename... TArgs> class AnalysisManager;
41template <class T> class ArrayRef;
42class AssumptionCache;
43class CallBase;
44class DataLayout;
45class DominatorTree;
46class Function;
47class Instruction;
48class CmpPredicate;
49class LoadInst;
50struct LoopStandardAnalysisResults;
51class Pass;
52template <class T, unsigned n> class SmallSetVector;
53class TargetLibraryInfo;
54class Type;
55class Value;
56
57// NOTE: the explicit multiple argument versions of these functions are
58// deprecated.
59// Please use the SimplifyQuery versions in new code.
60
61/// Given operands for an Add, fold the result or return null.
62LLVM_ABI Value *simplifyAddInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW,
63 const SimplifyQuery &Q);
64
65/// Given operands for a Sub, fold the result or return null.
66LLVM_ABI Value *simplifySubInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW,
67 const SimplifyQuery &Q);
68
69/// Given operands for a Mul, fold the result or return null.
70LLVM_ABI Value *simplifyMulInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW,
71 const SimplifyQuery &Q);
72
73/// Given operands for an SDiv, fold the result or return null.
74LLVM_ABI Value *simplifySDivInst(Value *LHS, Value *RHS, bool IsExact,
75 const SimplifyQuery &Q);
76
77/// Given operands for a UDiv, fold the result or return null.
78LLVM_ABI Value *simplifyUDivInst(Value *LHS, Value *RHS, bool IsExact,
79 const SimplifyQuery &Q);
80
81/// Given operands for an SRem, fold the result or return null.
82LLVM_ABI Value *simplifySRemInst(Value *LHS, Value *RHS,
83 const SimplifyQuery &Q);
84
85/// Given operands for a URem, fold the result or return null.
86LLVM_ABI Value *simplifyURemInst(Value *LHS, Value *RHS,
87 const SimplifyQuery &Q);
88
89/// Given operand for an FNeg, fold the result or return null.
90LLVM_ABI Value *simplifyFNegInst(Value *Op, FastMathFlags FMF,
91 const SimplifyQuery &Q);
92
93/// Given operands for an FAdd, fold the result or return null.
94LLVM_ABI Value *
95simplifyFAddInst(Value *LHS, Value *RHS, FastMathFlags FMF,
96 const SimplifyQuery &Q,
97 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
98 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
99
100/// Given operands for an FSub, fold the result or return null.
101LLVM_ABI Value *
102simplifyFSubInst(Value *LHS, Value *RHS, FastMathFlags FMF,
103 const SimplifyQuery &Q,
104 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
105 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
106
107/// Given operands for an FMul, fold the result or return null.
108LLVM_ABI Value *
109simplifyFMulInst(Value *LHS, Value *RHS, FastMathFlags FMF,
110 const SimplifyQuery &Q,
111 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
112 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
113
114/// Given operands for the multiplication of a FMA, fold the result or return
115/// null. In contrast to simplifyFMulInst, this function will not perform
116/// simplifications whose unrounded results differ when rounded to the argument
117/// type.
118LLVM_ABI Value *
119simplifyFMAFMul(Value *LHS, Value *RHS, FastMathFlags FMF,
120 const SimplifyQuery &Q,
121 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
122 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
123
124/// Given operands for an FDiv, fold the result or return null.
125LLVM_ABI Value *
126simplifyFDivInst(Value *LHS, Value *RHS, FastMathFlags FMF,
127 const SimplifyQuery &Q,
128 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
129 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
130
131/// Given operands for an FRem, fold the result or return null.
132LLVM_ABI Value *
133simplifyFRemInst(Value *LHS, Value *RHS, FastMathFlags FMF,
134 const SimplifyQuery &Q,
135 fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
136 RoundingMode Rounding = RoundingMode::NearestTiesToEven);
137
138/// Given operands for a Shl, fold the result or return null.
139LLVM_ABI Value *simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
140 const SimplifyQuery &Q);
141
142/// Given operands for a LShr, fold the result or return null.
143LLVM_ABI Value *simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact,
144 const SimplifyQuery &Q);
145
146/// Given operands for a AShr, fold the result or return nulll.
147LLVM_ABI Value *simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact,
148 const SimplifyQuery &Q);
149
150/// Given operands for an And, fold the result or return null.
151LLVM_ABI Value *simplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
152
153/// Given operands for an Or, fold the result or return null.
154LLVM_ABI Value *simplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
155
156/// Given operands for an Xor, fold the result or return null.
157LLVM_ABI Value *simplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
158
159/// Given operands for an ICmpInst, fold the result or return null.
160LLVM_ABI Value *simplifyICmpInst(CmpPredicate Pred, Value *LHS, Value *RHS,
161 const SimplifyQuery &Q);
162
163/// Given operands for an FCmpInst, fold the result or return null.
164LLVM_ABI Value *simplifyFCmpInst(CmpPredicate Predicate, Value *LHS, Value *RHS,
165 FastMathFlags FMF, const SimplifyQuery &Q);
166
167/// Given operands for a SelectInst, fold the result or return null.
168LLVM_ABI Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
169 const SimplifyQuery &Q);
170
171/// Given operands for a GetElementPtrInst, fold the result or return null.
172LLVM_ABI Value *simplifyGEPInst(Type *SrcTy, Value *Ptr,
173 ArrayRef<Value *> Indices, GEPNoWrapFlags NW,
174 const SimplifyQuery &Q);
175
176/// Given operands for an InsertValueInst, fold the result or return null.
177LLVM_ABI Value *simplifyInsertValueInst(Value *Agg, Value *Val,
178 ArrayRef<unsigned> Idxs,
179 const SimplifyQuery &Q);
180
181/// Given operands for an InsertElement, fold the result or return null.
182LLVM_ABI Value *simplifyInsertElementInst(Value *Vec, Value *Elt, Value *Idx,
183 const SimplifyQuery &Q);
184
185/// Given operands for an ExtractValueInst, fold the result or return null.
186LLVM_ABI Value *simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs,
187 const SimplifyQuery &Q);
188
189/// Given operands for an ExtractElementInst, fold the result or return null.
190LLVM_ABI Value *simplifyExtractElementInst(Value *Vec, Value *Idx,
191 const SimplifyQuery &Q);
192
193/// Given operands for a CastInst, fold the result or return null.
194LLVM_ABI Value *simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
195 const SimplifyQuery &Q);
196
197/// Given operands for a BinaryIntrinsic, fold the result or return null.
198LLVM_ABI Value *simplifyBinaryIntrinsic(Intrinsic::ID IID, Type *ReturnType,
199 Value *Op0, Value *Op1,
200 const SimplifyQuery &Q,
201 const CallBase *Call);
202
203/// Given operands for a ShuffleVectorInst, fold the result or return null.
204/// See class ShuffleVectorInst for a description of the mask representation.
205LLVM_ABI Value *simplifyShuffleVectorInst(Value *Op0, Value *Op1,
206 ArrayRef<int> Mask, Type *RetTy,
207 const SimplifyQuery &Q);
208
209//=== Helper functions for higher up the class hierarchy.
210
211/// Given operands for a CmpInst, fold the result or return null.
212LLVM_ABI Value *simplifyCmpInst(CmpPredicate Predicate, Value *LHS, Value *RHS,
213 const SimplifyQuery &Q);
214
215/// Given operand for a UnaryOperator, fold the result or return null.
216LLVM_ABI Value *simplifyUnOp(unsigned Opcode, Value *Op,
217 const SimplifyQuery &Q);
218
219/// Given operand for a UnaryOperator, fold the result or return null.
220/// Try to use FastMathFlags when folding the result.
221LLVM_ABI Value *simplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF,
222 const SimplifyQuery &Q);
223
224/// Given operands for a BinaryOperator, fold the result or return null.
225LLVM_ABI Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
226 const SimplifyQuery &Q);
227
228/// Given operands for a BinaryOperator, fold the result or return null.
229/// Try to use FastMathFlags when folding the result.
230LLVM_ABI Value *simplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
231 FastMathFlags FMF, const SimplifyQuery &Q);
232
233/// Given a callsite, callee, and arguments, fold the result or return null.
234LLVM_ABI Value *simplifyCall(CallBase *Call, Value *Callee,
235 ArrayRef<Value *> Args, const SimplifyQuery &Q);
236
237/// Given a constrained FP intrinsic call, tries to compute its simplified
238/// version. Returns a simplified result or null.
239///
240/// This function provides an additional contract: it guarantees that if
241/// simplification succeeds that the intrinsic is side effect free. As a result,
242/// successful simplification can be used to delete the intrinsic not just
243/// replace its result.
244LLVM_ABI Value *simplifyConstrainedFPCall(CallBase *Call,
245 const SimplifyQuery &Q);
246
247/// Given an operand for a Freeze, see if we can fold the result.
248/// If not, this returns null.
249LLVM_ABI Value *simplifyFreezeInst(Value *Op, const SimplifyQuery &Q);
250
251/// Given a load instruction and its pointer operand, fold the result or return
252/// null.
253LLVM_ABI Value *simplifyLoadInst(LoadInst *LI, Value *PtrOp,
254 const SimplifyQuery &Q);
255
256/// See if we can compute a simplified version of this instruction. If not,
257/// return null.
258LLVM_ABI Value *simplifyInstruction(Instruction *I, const SimplifyQuery &Q);
259
260/// Like \p simplifyInstruction but the operands of \p I are replaced with
261/// \p NewOps. Returns a simplified value, or null if none was found.
262LLVM_ABI Value *simplifyInstructionWithOperands(Instruction *I,
263 ArrayRef<Value *> NewOps,
264 const SimplifyQuery &Q);
265
266/// See if V simplifies when its operand Op is replaced with RepOp. If not,
267/// return null.
268/// AllowRefinement specifies whether the simplification can be a refinement
269/// (e.g. 0 instead of poison), or whether it needs to be strictly identical.
270/// Op and RepOp can be assumed to not be poison when determining refinement.
271///
272/// If DropFlags is passed, then the replacement result is only valid if
273/// poison-generating flags/metadata on those instructions are dropped. This
274/// is only useful in conjunction with AllowRefinement=false.
275LLVM_ABI Value *
276simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
277 const SimplifyQuery &Q, bool AllowRefinement,
278 SmallVectorImpl<Instruction *> *DropFlags = nullptr);
279
280/// Replace all uses of 'I' with 'SimpleV' and simplify the uses recursively.
281///
282/// This first performs a normal RAUW of I with SimpleV. It then recursively
283/// attempts to simplify those users updated by the operation. The 'I'
284/// instruction must not be equal to the simplified value 'SimpleV'.
285/// If UnsimplifiedUsers is provided, instructions that could not be simplified
286/// are added to it.
287///
288/// The function returns true if any simplifications were performed.
289LLVM_ABI bool replaceAndRecursivelySimplify(
290 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI = nullptr,
291 const DominatorTree *DT = nullptr, AssumptionCache *AC = nullptr,
292 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr);
293
294// These helper functions return a SimplifyQuery structure that contains as
295// many of the optional analysis we use as are currently valid. This is the
296// strongly preferred way of constructing SimplifyQuery in passes.
297LLVM_ABI const SimplifyQuery getBestSimplifyQuery(Pass &, Function &);
298template <class T, class... TArgs>
299const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &,
300 Function &);
301LLVM_ABI const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &,
302 const DataLayout &);
303} // end namespace llvm
304
305#endif
306

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