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/ADT/SetVector.h" 35 #include "llvm/IR/Instruction.h" 36 #include "llvm/IR/Operator.h" 37 #include "llvm/IR/User.h" 38 39 namespace llvm { 40 class Function; 41 template <typename T, typename... TArgs> class AnalysisManager; 42 template <class T> class ArrayRef; 43 class AssumptionCache; 44 class CallBase; 45 class DominatorTree; 46 class DataLayout; 47 class FastMathFlags; 48 struct LoopStandardAnalysisResults; 49 class OptimizationRemarkEmitter; 50 class Pass; 51 class TargetLibraryInfo; 52 class Type; 53 class Value; 54 class MDNode; 55 class BinaryOperator; 56 57 /// InstrInfoQuery provides an interface to query additional information for 58 /// instructions like metadata or keywords like nsw, which provides conservative 59 /// results if the users specified it is safe to use. 60 struct InstrInfoQuery { InstrInfoQueryInstrInfoQuery61 InstrInfoQuery(bool UMD) : UseInstrInfo(UMD) {} InstrInfoQueryInstrInfoQuery62 InstrInfoQuery() : UseInstrInfo(true) {} 63 bool UseInstrInfo = true; 64 getMetadataInstrInfoQuery65 MDNode *getMetadata(const Instruction *I, unsigned KindID) const { 66 if (UseInstrInfo) 67 return I->getMetadata(KindID); 68 return nullptr; 69 } 70 hasNoUnsignedWrapInstrInfoQuery71 template <class InstT> bool hasNoUnsignedWrap(const InstT *Op) const { 72 if (UseInstrInfo) 73 return Op->hasNoUnsignedWrap(); 74 return false; 75 } 76 hasNoSignedWrapInstrInfoQuery77 template <class InstT> bool hasNoSignedWrap(const InstT *Op) const { 78 if (UseInstrInfo) 79 return Op->hasNoSignedWrap(); 80 return false; 81 } 82 isExactInstrInfoQuery83 bool isExact(const BinaryOperator *Op) const { 84 if (UseInstrInfo && isa<PossiblyExactOperator>(Op)) 85 return cast<PossiblyExactOperator>(Op)->isExact(); 86 return false; 87 } 88 }; 89 90 struct SimplifyQuery { 91 const DataLayout &DL; 92 const TargetLibraryInfo *TLI = nullptr; 93 const DominatorTree *DT = nullptr; 94 AssumptionCache *AC = nullptr; 95 const Instruction *CxtI = nullptr; 96 97 // Wrapper to query additional information for instructions like metadata or 98 // keywords like nsw, which provides conservative results if those cannot 99 // be safely used. 100 const InstrInfoQuery IIQ; 101 102 SimplifyQuery(const DataLayout &DL, const Instruction *CXTI = nullptr) DLSimplifyQuery103 : DL(DL), CxtI(CXTI) {} 104 105 SimplifyQuery(const DataLayout &DL, const TargetLibraryInfo *TLI, 106 const DominatorTree *DT = nullptr, 107 AssumptionCache *AC = nullptr, 108 const Instruction *CXTI = nullptr, bool UseInstrInfo = true) DLSimplifyQuery109 : DL(DL), TLI(TLI), DT(DT), AC(AC), CxtI(CXTI), IIQ(UseInstrInfo) {} getWithInstructionSimplifyQuery110 SimplifyQuery getWithInstruction(Instruction *I) const { 111 SimplifyQuery Copy(*this); 112 Copy.CxtI = I; 113 return Copy; 114 } 115 }; 116 117 // NOTE: the explicit multiple argument versions of these functions are 118 // deprecated. 119 // Please use the SimplifyQuery versions in new code. 120 121 /// Given operand for an FNeg, fold the result or return null. 122 Value *SimplifyFNegInst(Value *Op, FastMathFlags FMF, 123 const SimplifyQuery &Q); 124 125 /// Given operands for an Add, fold the result or return null. 126 Value *SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW, 127 const SimplifyQuery &Q); 128 129 /// Given operands for a Sub, fold the result or return null. 130 Value *SimplifySubInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW, 131 const SimplifyQuery &Q); 132 133 /// Given operands for an FAdd, fold the result or return null. 134 Value *SimplifyFAddInst(Value *LHS, Value *RHS, FastMathFlags FMF, 135 const SimplifyQuery &Q); 136 137 /// Given operands for an FSub, fold the result or return null. 138 Value *SimplifyFSubInst(Value *LHS, Value *RHS, FastMathFlags FMF, 139 const SimplifyQuery &Q); 140 141 /// Given operands for an FMul, fold the result or return null. 142 Value *SimplifyFMulInst(Value *LHS, Value *RHS, FastMathFlags FMF, 143 const SimplifyQuery &Q); 144 145 /// Given operands for the multiplication of a FMA, fold the result or return 146 /// null. In contrast to SimplifyFMulInst, this function will not perform 147 /// simplifications whose unrounded results differ when rounded to the argument 148 /// type. 149 Value *SimplifyFMAFMul(Value *LHS, Value *RHS, FastMathFlags FMF, 150 const SimplifyQuery &Q); 151 152 /// Given operands for a Mul, fold the result or return null. 153 Value *SimplifyMulInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 154 155 /// Given operands for an SDiv, fold the result or return null. 156 Value *SimplifySDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 157 158 /// Given operands for a UDiv, fold the result or return null. 159 Value *SimplifyUDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 160 161 /// Given operands for an FDiv, fold the result or return null. 162 Value *SimplifyFDivInst(Value *LHS, Value *RHS, FastMathFlags FMF, 163 const SimplifyQuery &Q); 164 165 /// Given operands for an SRem, fold the result or return null. 166 Value *SimplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 167 168 /// Given operands for a URem, fold the result or return null. 169 Value *SimplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 170 171 /// Given operands for an FRem, fold the result or return null. 172 Value *SimplifyFRemInst(Value *LHS, Value *RHS, FastMathFlags FMF, 173 const SimplifyQuery &Q); 174 175 /// Given operands for a Shl, fold the result or return null. 176 Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, 177 const SimplifyQuery &Q); 178 179 /// Given operands for a LShr, fold the result or return null. 180 Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 181 const SimplifyQuery &Q); 182 183 /// Given operands for a AShr, fold the result or return nulll. 184 Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 185 const SimplifyQuery &Q); 186 187 /// Given operands for an And, fold the result or return null. 188 Value *SimplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 189 190 /// Given operands for an Or, fold the result or return null. 191 Value *SimplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 192 193 /// Given operands for an Xor, fold the result or return null. 194 Value *SimplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 195 196 /// Given operands for an ICmpInst, fold the result or return null. 197 Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 198 const SimplifyQuery &Q); 199 200 /// Given operands for an FCmpInst, fold the result or return null. 201 Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 202 FastMathFlags FMF, const SimplifyQuery &Q); 203 204 /// Given operands for a SelectInst, fold the result or return null. 205 Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 206 const SimplifyQuery &Q); 207 208 /// Given operands for a GetElementPtrInst, fold the result or return null. 209 Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops, 210 const SimplifyQuery &Q); 211 212 /// Given operands for an InsertValueInst, fold the result or return null. 213 Value *SimplifyInsertValueInst(Value *Agg, Value *Val, ArrayRef<unsigned> Idxs, 214 const SimplifyQuery &Q); 215 216 /// Given operands for an InsertElement, fold the result or return null. 217 Value *SimplifyInsertElementInst(Value *Vec, Value *Elt, Value *Idx, 218 const SimplifyQuery &Q); 219 220 /// Given operands for an ExtractValueInst, fold the result or return null. 221 Value *SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 222 const SimplifyQuery &Q); 223 224 /// Given operands for an ExtractElementInst, fold the result or return null. 225 Value *SimplifyExtractElementInst(Value *Vec, Value *Idx, 226 const SimplifyQuery &Q); 227 228 /// Given operands for a CastInst, fold the result or return null. 229 Value *SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 230 const SimplifyQuery &Q); 231 232 /// Given operands for a ShuffleVectorInst, fold the result or return null. 233 Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, Constant *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. 239 Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 240 const SimplifyQuery &Q); 241 242 /// Given operand for a UnaryOperator, fold the result or return null. 243 Value *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. 247 Value *SimplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF, 248 const SimplifyQuery &Q); 249 250 /// Given operands for a BinaryOperator, fold the result or return null. 251 Value *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. 256 Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, 257 FastMathFlags FMF, const SimplifyQuery &Q); 258 259 /// Given a callsite, fold the result or return null. 260 Value *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. 264 Value *SimplifyFreezeInst(Value *Op, const SimplifyQuery &Q); 265 266 /// See if we can compute a simplified version of this instruction. If not, 267 /// return null. 268 Value *SimplifyInstruction(Instruction *I, const SimplifyQuery &Q, 269 OptimizationRemarkEmitter *ORE = nullptr); 270 271 /// Replace all uses of 'I' with 'SimpleV' and simplify the uses recursively. 272 /// 273 /// This first performs a normal RAUW of I with SimpleV. It then recursively 274 /// attempts to simplify those users updated by the operation. The 'I' 275 /// instruction must not be equal to the simplified value 'SimpleV'. 276 /// If UnsimplifiedUsers is provided, instructions that could not be simplified 277 /// are added to it. 278 /// 279 /// The function returns true if any simplifications were performed. 280 bool replaceAndRecursivelySimplify( 281 Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI = nullptr, 282 const DominatorTree *DT = nullptr, AssumptionCache *AC = nullptr, 283 SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr); 284 285 /// Recursively attempt to simplify an instruction. 286 /// 287 /// This routine uses SimplifyInstruction to simplify 'I', and if successful 288 /// replaces uses of 'I' with the simplified value. It then recurses on each 289 /// of the users impacted. It returns true if any simplifications were 290 /// performed. 291 bool recursivelySimplifyInstruction(Instruction *I, 292 const TargetLibraryInfo *TLI = nullptr, 293 const DominatorTree *DT = nullptr, 294 AssumptionCache *AC = nullptr); 295 296 // These helper functions return a SimplifyQuery structure that contains as 297 // many of the optional analysis we use as are currently valid. This is the 298 // strongly preferred way of constructing SimplifyQuery in passes. 299 const SimplifyQuery getBestSimplifyQuery(Pass &, Function &); 300 template <class T, class... TArgs> 301 const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &, 302 Function &); 303 const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &, 304 const DataLayout &); 305 } // end namespace llvm 306 307 #endif 308 309