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 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 class Instruction; 48 class LoadInst; 49 struct LoopStandardAnalysisResults; 50 class Pass; 51 template <class T, unsigned n> class SmallSetVector; 52 class TargetLibraryInfo; 53 class Type; 54 class 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. 61 Value *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. 65 Value *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. 69 Value *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. 73 Value *simplifySDivInst(Value *LHS, Value *RHS, bool IsExact, 74 const SimplifyQuery &Q); 75 76 /// Given operands for a UDiv, fold the result or return null. 77 Value *simplifyUDivInst(Value *LHS, Value *RHS, bool IsExact, 78 const SimplifyQuery &Q); 79 80 /// Given operands for an SRem, fold the result or return null. 81 Value *simplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 82 83 /// Given operands for a URem, fold the result or return null. 84 Value *simplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 85 86 /// Given operand for an FNeg, fold the result or return null. 87 Value *simplifyFNegInst(Value *Op, FastMathFlags FMF, const SimplifyQuery &Q); 88 89 90 /// Given operands for an FAdd, fold the result or return null. 91 Value * 92 simplifyFAddInst(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. 98 Value * 99 simplifyFSubInst(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. 105 Value * 106 simplifyFMulInst(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. 115 Value *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. 121 Value * 122 simplifyFDivInst(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. 128 Value * 129 simplifyFRemInst(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. 135 Value *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. 139 Value *simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact, 140 const SimplifyQuery &Q); 141 142 /// Given operands for a AShr, fold the result or return nulll. 143 Value *simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact, 144 const SimplifyQuery &Q); 145 146 /// Given operands for an And, fold the result or return null. 147 Value *simplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 148 149 /// Given operands for an Or, fold the result or return null. 150 Value *simplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 151 152 /// Given operands for an Xor, fold the result or return null. 153 Value *simplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q); 154 155 /// Given operands for an ICmpInst, fold the result or return null. 156 Value *simplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, 157 const SimplifyQuery &Q); 158 159 /// Given operands for an FCmpInst, fold the result or return null. 160 Value *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. 164 Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, 165 const SimplifyQuery &Q); 166 167 /// Given operands for a GetElementPtrInst, fold the result or return null. 168 Value *simplifyGEPInst(Type *SrcTy, Value *Ptr, ArrayRef<Value *> Indices, 169 GEPNoWrapFlags NW, const SimplifyQuery &Q); 170 171 /// Given operands for an InsertValueInst, fold the result or return null. 172 Value *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. 176 Value *simplifyInsertElementInst(Value *Vec, Value *Elt, Value *Idx, 177 const SimplifyQuery &Q); 178 179 /// Given operands for an ExtractValueInst, fold the result or return null. 180 Value *simplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs, 181 const SimplifyQuery &Q); 182 183 /// Given operands for an ExtractElementInst, fold the result or return null. 184 Value *simplifyExtractElementInst(Value *Vec, Value *Idx, 185 const SimplifyQuery &Q); 186 187 /// Given operands for a CastInst, fold the result or return null. 188 Value *simplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty, 189 const SimplifyQuery &Q); 190 191 /// Given operands for a BinaryIntrinsic, fold the result or return null. 192 Value *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. 198 Value *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. 204 Value *simplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, 205 const SimplifyQuery &Q); 206 207 /// Given operand for a UnaryOperator, fold the result or return null. 208 Value *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. 212 Value *simplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF, 213 const SimplifyQuery &Q); 214 215 /// Given operands for a BinaryOperator, fold the result or return null. 216 Value *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. 221 Value *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. 225 Value *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. 235 Value *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. 239 Value *simplifyFreezeInst(Value *Op, const SimplifyQuery &Q); 240 241 /// Given a load instruction and its pointer operand, fold the result or return 242 /// null. 243 Value *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. 247 Value *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. 251 Value * 252 simplifyInstructionWithOperands(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. 264 Value * 265 simplifyWithOpReplaced(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. 278 bool 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. 286 const SimplifyQuery getBestSimplifyQuery(Pass &, Function &); 287 template <class T, class... TArgs> 288 const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &, 289 Function &); 290 const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &, 291 const DataLayout &); 292 } // end namespace llvm 293 294 #endif 295