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 37 namespace llvm { 38 39 template <typename T, typename... TArgs> class AnalysisManager; 40 template <class T> class ArrayRef; 41 class AssumptionCache; 42 class BinaryOperator; 43 class CallBase; 44 class DataLayout; 45 class DominatorTree; 46 class Function; 47 struct LoopStandardAnalysisResults; 48 class MDNode; 49 class OptimizationRemarkEmitter; 50 class Pass; 51 template <class T, unsigned n> class SmallSetVector; 52 class TargetLibraryInfo; 53 class Type; 54 class 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. 59 struct InstrInfoQuery { InstrInfoQueryInstrInfoQuery60 InstrInfoQuery(bool UMD) : UseInstrInfo(UMD) {} InstrInfoQueryInstrInfoQuery61 InstrInfoQuery() : UseInstrInfo(true) {} 62 bool UseInstrInfo = true; 63 getMetadataInstrInfoQuery64 MDNode *getMetadata(const Instruction *I, unsigned KindID) const { 65 if (UseInstrInfo) 66 return I->getMetadata(KindID); 67 return nullptr; 68 } 69 hasNoUnsignedWrapInstrInfoQuery70 template <class InstT> bool hasNoUnsignedWrap(const InstT *Op) const { 71 if (UseInstrInfo) 72 return Op->hasNoUnsignedWrap(); 73 return false; 74 } 75 hasNoSignedWrapInstrInfoQuery76 template <class InstT> bool hasNoSignedWrap(const InstT *Op) const { 77 if (UseInstrInfo) 78 return Op->hasNoSignedWrap(); 79 return false; 80 } 81 isExactInstrInfoQuery82 bool isExact(const BinaryOperator *Op) const { 83 if (UseInstrInfo && isa<PossiblyExactOperator>(Op)) 84 return cast<PossiblyExactOperator>(Op)->isExact(); 85 return false; 86 } 87 }; 88 89 struct 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) DLSimplifyQuery102 : 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) DLSimplifyQuery108 : DL(DL), TLI(TLI), DT(DT), AC(AC), CxtI(CXTI), IIQ(UseInstrInfo) {} getWithInstructionSimplifyQuery109 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. 121 Value *SimplifyFNegInst(Value *Op, FastMathFlags FMF, 122 const SimplifyQuery &Q); 123 124 /// Given operands for an Add, fold the result or return null. 125 Value *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. 129 Value *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. 133 Value *SimplifyFAddInst(Value *LHS, Value *RHS, FastMathFlags FMF, 134 const SimplifyQuery &Q); 135 136 /// Given operands for an FSub, fold the result or return null. 137 Value *SimplifyFSubInst(Value *LHS, Value *RHS, FastMathFlags FMF, 138 const SimplifyQuery &Q); 139 140 /// Given operands for an FMul, fold the result or return null. 141 Value *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. 148 Value *SimplifyFMAFMul(Value *LHS, Value *RHS, FastMathFlags FMF, 149 const SimplifyQuery &Q); 150 151 /// Given operands for a Mul, fold the result or return null. 152 Value *SimplifyMulInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 153 154 /// Given operands for an SDiv, fold the result or return null. 155 Value *SimplifySDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 156 157 /// Given operands for a UDiv, fold the result or return null. 158 Value *SimplifyUDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 159 160 /// Given operands for an FDiv, fold the result or return null. 161 Value *SimplifyFDivInst(Value *LHS, Value *RHS, FastMathFlags FMF, 162 const SimplifyQuery &Q); 163 164 /// Given operands for an SRem, fold the result or return null. 165 Value *SimplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 166 167 /// Given operands for a URem, fold the result or return null. 168 Value *SimplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 169 170 /// Given operands for an FRem, fold the result or return null. 171 Value *SimplifyFRemInst(Value *LHS, Value *RHS, FastMathFlags FMF, 172 const SimplifyQuery &Q); 173 174 /// Given operands for a Shl, fold the result or return null. 175 Value *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. 179 Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact, 180 const SimplifyQuery &Q); 181 182 /// Given operands for a AShr, fold the result or return nulll. 183 Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact, 184 const SimplifyQuery &Q); 185 186 /// Given operands for an And, fold the result or return null. 187 Value *SimplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 188 189 /// Given operands for an Or, fold the result or return null. 190 Value *SimplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 191 192 /// Given operands for an Xor, fold the result or return null. 193 Value *SimplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 194 195 /// Given operands for an ICmpInst, fold the result or return null. 196 Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 197 const SimplifyQuery &Q); 198 199 /// Given operands for an FCmpInst, fold the result or return null. 200 Value *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. 204 Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 205 const SimplifyQuery &Q); 206 207 /// Given operands for a GetElementPtrInst, fold the result or return null. 208 Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops, 209 const SimplifyQuery &Q); 210 211 /// Given operands for an InsertValueInst, fold the result or return null. 212 Value *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. 216 Value *SimplifyInsertElementInst(Value *Vec, Value *Elt, Value *Idx, 217 const SimplifyQuery &Q); 218 219 /// Given operands for an ExtractValueInst, fold the result or return null. 220 Value *SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 221 const SimplifyQuery &Q); 222 223 /// Given operands for an ExtractElementInst, fold the result or return null. 224 Value *SimplifyExtractElementInst(Value *Vec, Value *Idx, 225 const SimplifyQuery &Q); 226 227 /// Given operands for a CastInst, fold the result or return null. 228 Value *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. 233 Value *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. 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 /// Return the underlying Value*, stripping all GEP, pointer cast and 297 /// setoffset/setaddr intrinsics (i.e. everything that keeps the non-address 298 /// bits of CHERI capabilities the same) 299 Value *getBasePtrIgnoringCapabilityAddressManipulation(Value *V, 300 const DataLayout &DL); 301 /// Similar to getBasePtrIgnoringCapabilityAddressManipulation but also strips 302 /// intrinsics that modify the capability metadata (including sealing and 303 /// cleartag) 304 Value *getBasePtrIgnoringCapabilityManipulation(Value *V, const DataLayout &DL); 305 306 // These helper functions return a SimplifyQuery structure that contains as 307 // many of the optional analysis we use as are currently valid. This is the 308 // strongly preferred way of constructing SimplifyQuery in passes. 309 const SimplifyQuery getBestSimplifyQuery(Pass &, Function &); 310 template <class T, class... TArgs> 311 const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &, 312 Function &); 313 const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &, 314 const DataLayout &); 315 } // end namespace llvm 316 317 #endif 318 319