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// These routines are designed to tolerate moderately incomplete IR, such as 23// instructions that are not connected to basic blocks yet. However, they do 24// require that all the IR that they encounter be valid. In particular, they 25// require that all non-constant values be defined in the same function, and the 26// same call context of that function (and not split between caller and callee 27// contexts of a directly recursive call, for example). 28// 29//===----------------------------------------------------------------------===// 30 31#ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H 32#define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H 33 34#include "llvm/IR/Instruction.h" 35#include "llvm/IR/Operator.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; 47struct LoopStandardAnalysisResults; 48class MDNode; 49class OptimizationRemarkEmitter; 50class Pass; 51template <class T, unsigned n> class SmallSetVector; 52class TargetLibraryInfo; 53class Type; 54class Value; 55 56/// InstrInfoQuery provides an interface to query additional information for 57/// instructions like metadata or keywords like nsw, which provides conservative 58/// results if the users specified it is safe to use. 59struct InstrInfoQuery { 60 InstrInfoQuery(bool UMD) : UseInstrInfo(UMD) {} 61 InstrInfoQuery() : UseInstrInfo(true) {} 62 bool UseInstrInfo = true; 63 64 MDNode *getMetadata(const Instruction *I, unsigned KindID) const { 65 if (UseInstrInfo) 66 return I->getMetadata(KindID); 67 return nullptr; 68 } 69 70 template <class InstT> bool hasNoUnsignedWrap(const InstT *Op) const { 71 if (UseInstrInfo) 72 return Op->hasNoUnsignedWrap(); 73 return false; 74 } 75 76 template <class InstT> bool hasNoSignedWrap(const InstT *Op) const { 77 if (UseInstrInfo) 78 return Op->hasNoSignedWrap(); 79 return false; 80 } 81 82 bool isExact(const BinaryOperator *Op) const { 83 if (UseInstrInfo && isa<PossiblyExactOperator>(Op)) 84 return cast<PossiblyExactOperator>(Op)->isExact(); 85 return false; 86 } 87}; 88 89struct SimplifyQuery { 90 const DataLayout &DL; 91 const TargetLibraryInfo *TLI = nullptr; 92 const DominatorTree *DT = nullptr; 93 AssumptionCache *AC = nullptr; 94 const Instruction *CxtI = nullptr; 95 96 // Wrapper to query additional information for instructions like metadata or 97 // keywords like nsw, which provides conservative results if those cannot 98 // be safely used. 99 const InstrInfoQuery IIQ; 100 101 SimplifyQuery(const DataLayout &DL, const Instruction *CXTI = nullptr) 102 : DL(DL), CxtI(CXTI) {} 103 104 SimplifyQuery(const DataLayout &DL, const TargetLibraryInfo *TLI, 105 const DominatorTree *DT = nullptr, 106 AssumptionCache *AC = nullptr, 107 const Instruction *CXTI = nullptr, bool UseInstrInfo = true) 108 : DL(DL), TLI(TLI), DT(DT), AC(AC), CxtI(CXTI), IIQ(UseInstrInfo) {} 109 SimplifyQuery getWithInstruction(Instruction *I) const { 110 SimplifyQuery Copy(*this); 111 Copy.CxtI = I; 112 return Copy; 113 } 114}; 115 116// NOTE: the explicit multiple argument versions of these functions are 117// deprecated. 118// Please use the SimplifyQuery versions in new code. 119 120/// Given operand for an FNeg, fold the result or return null. 121Value *SimplifyFNegInst(Value *Op, FastMathFlags FMF, 122 const SimplifyQuery &Q); 123 124/// Given operands for an Add, fold the result or return null. 125Value *SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW, 126 const SimplifyQuery &Q); 127 128/// Given operands for a Sub, fold the result or return null. 129Value *SimplifySubInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW, 130 const SimplifyQuery &Q); 131 132/// Given operands for an FAdd, fold the result or return null. 133Value *SimplifyFAddInst(Value *LHS, Value *RHS, FastMathFlags FMF, 134 const SimplifyQuery &Q); 135 136/// Given operands for an FSub, fold the result or return null. 137Value *SimplifyFSubInst(Value *LHS, Value *RHS, FastMathFlags FMF, 138 const SimplifyQuery &Q); 139 140/// Given operands for an FMul, fold the result or return null. 141Value *SimplifyFMulInst(Value *LHS, Value *RHS, FastMathFlags FMF, 142 const SimplifyQuery &Q); 143 144/// Given operands for the multiplication of a FMA, fold the result or return 145/// null. In contrast to SimplifyFMulInst, this function will not perform 146/// simplifications whose unrounded results differ when rounded to the argument 147/// type. 148Value *SimplifyFMAFMul(Value *LHS, Value *RHS, FastMathFlags FMF, 149 const SimplifyQuery &Q); 150 151/// Given operands for a Mul, fold the result or return null. 152Value *SimplifyMulInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 153 154/// Given operands for an SDiv, fold the result or return null. 155Value *SimplifySDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 156 157/// Given operands for a UDiv, fold the result or return null. 158Value *SimplifyUDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 159 160/// Given operands for an FDiv, fold the result or return null. 161Value *SimplifyFDivInst(Value *LHS, Value *RHS, FastMathFlags FMF, 162 const SimplifyQuery &Q); 163 164/// Given operands for an SRem, fold the result or return null. 165Value *SimplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 166 167/// Given operands for a URem, fold the result or return null. 168Value *SimplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 169 170/// Given operands for an FRem, fold the result or return null. 171Value *SimplifyFRemInst(Value *LHS, Value *RHS, FastMathFlags FMF, 172 const SimplifyQuery &Q); 173 174/// Given operands for a Shl, fold the result or return null. 175Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 176 const SimplifyQuery &Q); 177 178/// Given operands for a LShr, fold the result or return null. 179Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 180 const SimplifyQuery &Q); 181 182/// Given operands for a AShr, fold the result or return nulll. 183Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 184 const SimplifyQuery &Q); 185 186/// Given operands for an And, fold the result or return null. 187Value *SimplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 188 189/// Given operands for an Or, fold the result or return null. 190Value *SimplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 191 192/// Given operands for an Xor, fold the result or return null. 193Value *SimplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 194 195/// Given operands for an ICmpInst, fold the result or return null. 196Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 197 const SimplifyQuery &Q); 198 199/// Given operands for an FCmpInst, fold the result or return null. 200Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 201 FastMathFlags FMF, const SimplifyQuery &Q); 202 203/// Given operands for a SelectInst, fold the result or return null. 204Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 205 const SimplifyQuery &Q); 206 207/// Given operands for a GetElementPtrInst, fold the result or return null. 208Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops, 209 const SimplifyQuery &Q); 210 211/// Given operands for an InsertValueInst, fold the result or return null. 212Value *SimplifyInsertValueInst(Value *Agg, Value *Val, ArrayRef<unsigned> Idxs, 213 const SimplifyQuery &Q); 214 215/// Given operands for an InsertElement, fold the result or return null. 216Value *SimplifyInsertElementInst(Value *Vec, Value *Elt, Value *Idx, 217 const SimplifyQuery &Q); 218 219/// Given operands for an ExtractValueInst, fold the result or return null. 220Value *SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 221 const SimplifyQuery &Q); 222 223/// Given operands for an ExtractElementInst, fold the result or return null. 224Value *SimplifyExtractElementInst(Value *Vec, Value *Idx, 225 const SimplifyQuery &Q); 226 227/// Given operands for a CastInst, fold the result or return null. 228Value *SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 229 const SimplifyQuery &Q); 230 231/// Given operands for a ShuffleVectorInst, fold the result or return null. 232/// See class ShuffleVectorInst for a description of the mask representation. 233Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, ArrayRef<int> Mask, 234 Type *RetTy, const SimplifyQuery &Q); 235 236//=== Helper functions for higher up the class hierarchy. 237 238/// Given operands for a CmpInst, fold the result or return null. 239Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 240 const SimplifyQuery &Q); 241 242/// Given operand for a UnaryOperator, fold the result or return null. 243Value *SimplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q); 244 245/// Given operand for a UnaryOperator, fold the result or return null. 246/// Try to use FastMathFlags when folding the result. 247Value *SimplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF, 248 const SimplifyQuery &Q); 249 250/// Given operands for a BinaryOperator, fold the result or return null. 251Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 252 const SimplifyQuery &Q); 253 254/// Given operands for a BinaryOperator, fold the result or return null. 255/// Try to use FastMathFlags when folding the result. 256Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 257 FastMathFlags FMF, const SimplifyQuery &Q); 258 259/// Given a callsite, fold the result or return null. 260Value *SimplifyCall(CallBase *Call, const SimplifyQuery &Q); 261 262/// Given an operand for a Freeze, see if we can fold the result. 263/// If not, this returns null. 264Value *SimplifyFreezeInst(Value *Op, const SimplifyQuery &Q); 265 266/// See if we can compute a simplified version of this instruction. If not, 267/// return null. 268Value *SimplifyInstruction(Instruction *I, const SimplifyQuery &Q, 269 OptimizationRemarkEmitter *ORE = nullptr); 270 271/// See if V simplifies when its operand Op is replaced with RepOp. 272/// AllowRefinement specifies whether the simplification can be a refinement, 273/// or whether it needs to be strictly identical. 274Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, 275 const SimplifyQuery &Q, bool AllowRefinement); 276 277/// Replace all uses of 'I' with 'SimpleV' and simplify the uses recursively. 278/// 279/// This first performs a normal RAUW of I with SimpleV. It then recursively 280/// attempts to simplify those users updated by the operation. The 'I' 281/// instruction must not be equal to the simplified value 'SimpleV'. 282/// If UnsimplifiedUsers is provided, instructions that could not be simplified 283/// are added to it. 284/// 285/// The function returns true if any simplifications were performed. 286bool replaceAndRecursivelySimplify( 287 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI = nullptr, 288 const DominatorTree *DT = nullptr, AssumptionCache *AC = nullptr, 289 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr); 290 291/// Recursively attempt to simplify an instruction. 292/// 293/// This routine uses SimplifyInstruction to simplify 'I', and if successful 294/// replaces uses of 'I' with the simplified value. It then recurses on each 295/// of the users impacted. It returns true if any simplifications were 296/// performed. 297bool recursivelySimplifyInstruction(Instruction *I, 298 const TargetLibraryInfo *TLI = nullptr, 299 const DominatorTree *DT = nullptr, 300 AssumptionCache *AC = nullptr); 301 302// These helper functions return a SimplifyQuery structure that contains as 303// many of the optional analysis we use as are currently valid. This is the 304// strongly preferred way of constructing SimplifyQuery in passes. 305const SimplifyQuery getBestSimplifyQuery(Pass &, Function &); 306template <class T, class... TArgs> 307const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &, 308 Function &); 309const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &, 310 const DataLayout &); 311} // end namespace llvm 312 313#endif 314 315