1 //===- InstCombineInternal.h - InstCombine pass internals -------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 /// \file 10 /// 11 /// This file provides internal interfaces used to implement the InstCombine. 12 /// 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEINTERNAL_H 16 #define LLVM_LIB_TRANSFORMS_INSTCOMBINE_INSTCOMBINEINTERNAL_H 17 18 #include "llvm/Analysis/AliasAnalysis.h" 19 #include "llvm/Analysis/AssumptionCache.h" 20 #include "llvm/Analysis/LoopInfo.h" 21 #include "llvm/Analysis/TargetFolder.h" 22 #include "llvm/Analysis/ValueTracking.h" 23 #include "llvm/IR/Dominators.h" 24 #include "llvm/IR/IRBuilder.h" 25 #include "llvm/IR/InstVisitor.h" 26 #include "llvm/IR/IntrinsicInst.h" 27 #include "llvm/IR/Operator.h" 28 #include "llvm/IR/PatternMatch.h" 29 #include "llvm/Pass.h" 30 #include "llvm/Transforms/InstCombine/InstCombineWorklist.h" 31 32 #define DEBUG_TYPE "instcombine" 33 34 namespace llvm { 35 class CallSite; 36 class DataLayout; 37 class DominatorTree; 38 class TargetLibraryInfo; 39 class DbgDeclareInst; 40 class MemIntrinsic; 41 class MemSetInst; 42 43 /// \brief Assign a complexity or rank value to LLVM Values. 44 /// 45 /// This routine maps IR values to various complexity ranks: 46 /// 0 -> undef 47 /// 1 -> Constants 48 /// 2 -> Other non-instructions 49 /// 3 -> Arguments 50 /// 3 -> Unary operations 51 /// 4 -> Other instructions 52 static inline unsigned getComplexity(Value *V) { 53 if (isa<Instruction>(V)) { 54 if (BinaryOperator::isNeg(V) || BinaryOperator::isFNeg(V) || 55 BinaryOperator::isNot(V)) 56 return 3; 57 return 4; 58 } 59 if (isa<Argument>(V)) 60 return 3; 61 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2; 62 } 63 64 /// \brief Add one to a Constant 65 static inline Constant *AddOne(Constant *C) { 66 return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1)); 67 } 68 /// \brief Subtract one from a Constant 69 static inline Constant *SubOne(Constant *C) { 70 return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1)); 71 } 72 73 /// \brief Return true if the specified value is free to invert (apply ~ to). 74 /// This happens in cases where the ~ can be eliminated. If WillInvertAllUses 75 /// is true, work under the assumption that the caller intends to remove all 76 /// uses of V and only keep uses of ~V. 77 /// 78 static inline bool IsFreeToInvert(Value *V, bool WillInvertAllUses) { 79 // ~(~(X)) -> X. 80 if (BinaryOperator::isNot(V)) 81 return true; 82 83 // Constants can be considered to be not'ed values. 84 if (isa<ConstantInt>(V)) 85 return true; 86 87 // Compares can be inverted if all of their uses are being modified to use the 88 // ~V. 89 if (isa<CmpInst>(V)) 90 return WillInvertAllUses; 91 92 // If `V` is of the form `A + Constant` then `-1 - V` can be folded into `(-1 93 // - Constant) - A` if we are willing to invert all of the uses. 94 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V)) 95 if (BO->getOpcode() == Instruction::Add || 96 BO->getOpcode() == Instruction::Sub) 97 if (isa<Constant>(BO->getOperand(0)) || isa<Constant>(BO->getOperand(1))) 98 return WillInvertAllUses; 99 100 return false; 101 } 102 103 104 /// \brief Specific patterns of overflow check idioms that we match. 105 enum OverflowCheckFlavor { 106 OCF_UNSIGNED_ADD, 107 OCF_SIGNED_ADD, 108 OCF_UNSIGNED_SUB, 109 OCF_SIGNED_SUB, 110 OCF_UNSIGNED_MUL, 111 OCF_SIGNED_MUL, 112 113 OCF_INVALID 114 }; 115 116 /// \brief Returns the OverflowCheckFlavor corresponding to a overflow_with_op 117 /// intrinsic. 118 static inline OverflowCheckFlavor 119 IntrinsicIDToOverflowCheckFlavor(unsigned ID) { 120 switch (ID) { 121 default: 122 return OCF_INVALID; 123 case Intrinsic::uadd_with_overflow: 124 return OCF_UNSIGNED_ADD; 125 case Intrinsic::sadd_with_overflow: 126 return OCF_SIGNED_ADD; 127 case Intrinsic::usub_with_overflow: 128 return OCF_UNSIGNED_SUB; 129 case Intrinsic::ssub_with_overflow: 130 return OCF_SIGNED_SUB; 131 case Intrinsic::umul_with_overflow: 132 return OCF_UNSIGNED_MUL; 133 case Intrinsic::smul_with_overflow: 134 return OCF_SIGNED_MUL; 135 } 136 } 137 138 /// \brief An IRBuilder inserter that adds new instructions to the instcombine 139 /// worklist. 140 class LLVM_LIBRARY_VISIBILITY InstCombineIRInserter 141 : public IRBuilderDefaultInserter<true> { 142 InstCombineWorklist &Worklist; 143 AssumptionCache *AC; 144 145 public: 146 InstCombineIRInserter(InstCombineWorklist &WL, AssumptionCache *AC) 147 : Worklist(WL), AC(AC) {} 148 149 void InsertHelper(Instruction *I, const Twine &Name, BasicBlock *BB, 150 BasicBlock::iterator InsertPt) const { 151 IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt); 152 Worklist.Add(I); 153 154 using namespace llvm::PatternMatch; 155 if (match(I, m_Intrinsic<Intrinsic::assume>())) 156 AC->registerAssumption(cast<CallInst>(I)); 157 } 158 }; 159 160 /// \brief The core instruction combiner logic. 161 /// 162 /// This class provides both the logic to recursively visit instructions and 163 /// combine them, as well as the pass infrastructure for running this as part 164 /// of the LLVM pass pipeline. 165 class LLVM_LIBRARY_VISIBILITY InstCombiner 166 : public InstVisitor<InstCombiner, Instruction *> { 167 // FIXME: These members shouldn't be public. 168 public: 169 /// \brief A worklist of the instructions that need to be simplified. 170 InstCombineWorklist &Worklist; 171 172 /// \brief An IRBuilder that automatically inserts new instructions into the 173 /// worklist. 174 typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy; 175 BuilderTy *Builder; 176 177 private: 178 // Mode in which we are running the combiner. 179 const bool MinimizeSize; 180 181 AliasAnalysis *AA; 182 183 // Required analyses. 184 // FIXME: These can never be null and should be references. 185 AssumptionCache *AC; 186 TargetLibraryInfo *TLI; 187 DominatorTree *DT; 188 const DataLayout &DL; 189 190 // Optional analyses. When non-null, these can both be used to do better 191 // combining and will be updated to reflect any changes. 192 LoopInfo *LI; 193 194 bool MadeIRChange; 195 196 public: 197 InstCombiner(InstCombineWorklist &Worklist, BuilderTy *Builder, 198 bool MinimizeSize, AliasAnalysis *AA, 199 AssumptionCache *AC, TargetLibraryInfo *TLI, 200 DominatorTree *DT, const DataLayout &DL, LoopInfo *LI) 201 : Worklist(Worklist), Builder(Builder), MinimizeSize(MinimizeSize), 202 AA(AA), AC(AC), TLI(TLI), DT(DT), DL(DL), LI(LI), MadeIRChange(false) {} 203 204 /// \brief Run the combiner over the entire worklist until it is empty. 205 /// 206 /// \returns true if the IR is changed. 207 bool run(); 208 209 AssumptionCache *getAssumptionCache() const { return AC; } 210 211 const DataLayout &getDataLayout() const { return DL; } 212 213 DominatorTree *getDominatorTree() const { return DT; } 214 215 LoopInfo *getLoopInfo() const { return LI; } 216 217 TargetLibraryInfo *getTargetLibraryInfo() const { return TLI; } 218 219 // Visitation implementation - Implement instruction combining for different 220 // instruction types. The semantics are as follows: 221 // Return Value: 222 // null - No change was made 223 // I - Change was made, I is still valid, I may be dead though 224 // otherwise - Change was made, replace I with returned instruction 225 // 226 Instruction *visitAdd(BinaryOperator &I); 227 Instruction *visitFAdd(BinaryOperator &I); 228 Value *OptimizePointerDifference(Value *LHS, Value *RHS, Type *Ty); 229 Instruction *visitSub(BinaryOperator &I); 230 Instruction *visitFSub(BinaryOperator &I); 231 Instruction *visitMul(BinaryOperator &I); 232 Value *foldFMulConst(Instruction *FMulOrDiv, Constant *C, 233 Instruction *InsertBefore); 234 Instruction *visitFMul(BinaryOperator &I); 235 Instruction *visitURem(BinaryOperator &I); 236 Instruction *visitSRem(BinaryOperator &I); 237 Instruction *visitFRem(BinaryOperator &I); 238 bool SimplifyDivRemOfSelect(BinaryOperator &I); 239 Instruction *commonRemTransforms(BinaryOperator &I); 240 Instruction *commonIRemTransforms(BinaryOperator &I); 241 Instruction *commonDivTransforms(BinaryOperator &I); 242 Instruction *commonIDivTransforms(BinaryOperator &I); 243 Instruction *visitUDiv(BinaryOperator &I); 244 Instruction *visitSDiv(BinaryOperator &I); 245 Instruction *visitFDiv(BinaryOperator &I); 246 Value *simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1, bool Inverted); 247 Value *FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS); 248 Value *FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS); 249 Instruction *visitAnd(BinaryOperator &I); 250 Value *FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction *CxtI); 251 Value *FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS); 252 Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op, Value *A, 253 Value *B, Value *C); 254 Instruction *FoldXorWithConstants(BinaryOperator &I, Value *Op, Value *A, 255 Value *B, Value *C); 256 Instruction *visitOr(BinaryOperator &I); 257 Instruction *visitXor(BinaryOperator &I); 258 Instruction *visitShl(BinaryOperator &I); 259 Instruction *visitAShr(BinaryOperator &I); 260 Instruction *visitLShr(BinaryOperator &I); 261 Instruction *commonShiftTransforms(BinaryOperator &I); 262 Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI, 263 Constant *RHSC); 264 Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, 265 GlobalVariable *GV, CmpInst &ICI, 266 ConstantInt *AndCst = nullptr); 267 Instruction *visitFCmpInst(FCmpInst &I); 268 Instruction *visitICmpInst(ICmpInst &I); 269 Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI); 270 Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI, Instruction *LHS, 271 ConstantInt *RHS); 272 Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI, 273 ConstantInt *DivRHS); 274 Instruction *FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *DivI, 275 ConstantInt *DivRHS); 276 Instruction *FoldICmpCstShrCst(ICmpInst &I, Value *Op, Value *A, 277 ConstantInt *CI1, ConstantInt *CI2); 278 Instruction *FoldICmpCstShlCst(ICmpInst &I, Value *Op, Value *A, 279 ConstantInt *CI1, ConstantInt *CI2); 280 Instruction *FoldICmpAddOpCst(Instruction &ICI, Value *X, ConstantInt *CI, 281 ICmpInst::Predicate Pred); 282 Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, 283 ICmpInst::Predicate Cond, Instruction &I); 284 Instruction *FoldAllocaCmp(ICmpInst &ICI, AllocaInst *Alloca, Value *Other); 285 Instruction *FoldShiftByConstant(Value *Op0, Constant *Op1, 286 BinaryOperator &I); 287 Instruction *commonCastTransforms(CastInst &CI); 288 Instruction *commonPointerCastTransforms(CastInst &CI); 289 Instruction *visitTrunc(TruncInst &CI); 290 Instruction *visitZExt(ZExtInst &CI); 291 Instruction *visitSExt(SExtInst &CI); 292 Instruction *visitFPTrunc(FPTruncInst &CI); 293 Instruction *visitFPExt(CastInst &CI); 294 Instruction *visitFPToUI(FPToUIInst &FI); 295 Instruction *visitFPToSI(FPToSIInst &FI); 296 Instruction *visitUIToFP(CastInst &CI); 297 Instruction *visitSIToFP(CastInst &CI); 298 Instruction *visitPtrToInt(PtrToIntInst &CI); 299 Instruction *visitIntToPtr(IntToPtrInst &CI); 300 Instruction *visitBitCast(BitCastInst &CI); 301 Instruction *visitAddrSpaceCast(AddrSpaceCastInst &CI); 302 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI, Instruction *FI); 303 Instruction *FoldSelectIntoOp(SelectInst &SI, Value *, Value *); 304 Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1, 305 Value *A, Value *B, Instruction &Outer, 306 SelectPatternFlavor SPF2, Value *C); 307 Instruction *FoldItoFPtoI(Instruction &FI); 308 Instruction *visitSelectInst(SelectInst &SI); 309 Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI); 310 Instruction *visitCallInst(CallInst &CI); 311 Instruction *visitInvokeInst(InvokeInst &II); 312 313 Instruction *SliceUpIllegalIntegerPHI(PHINode &PN); 314 Instruction *visitPHINode(PHINode &PN); 315 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP); 316 Instruction *visitAllocaInst(AllocaInst &AI); 317 Instruction *visitAllocSite(Instruction &FI); 318 Instruction *visitFree(CallInst &FI); 319 Instruction *visitLoadInst(LoadInst &LI); 320 Instruction *visitStoreInst(StoreInst &SI); 321 Instruction *visitBranchInst(BranchInst &BI); 322 Instruction *visitSwitchInst(SwitchInst &SI); 323 Instruction *visitReturnInst(ReturnInst &RI); 324 Instruction *visitInsertValueInst(InsertValueInst &IV); 325 Instruction *visitInsertElementInst(InsertElementInst &IE); 326 Instruction *visitExtractElementInst(ExtractElementInst &EI); 327 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI); 328 Instruction *visitExtractValueInst(ExtractValueInst &EV); 329 Instruction *visitLandingPadInst(LandingPadInst &LI); 330 331 // visitInstruction - Specify what to return for unhandled instructions... 332 Instruction *visitInstruction(Instruction &I) { return nullptr; } 333 334 // True when DB dominates all uses of DI execpt UI. 335 // UI must be in the same block as DI. 336 // The routine checks that the DI parent and DB are different. 337 bool dominatesAllUses(const Instruction *DI, const Instruction *UI, 338 const BasicBlock *DB) const; 339 340 // Replace select with select operand SIOpd in SI-ICmp sequence when possible 341 bool replacedSelectWithOperand(SelectInst *SI, const ICmpInst *Icmp, 342 const unsigned SIOpd); 343 344 private: 345 bool ShouldChangeType(unsigned FromBitWidth, unsigned ToBitWidth) const; 346 bool ShouldChangeType(Type *From, Type *To) const; 347 Value *dyn_castNegVal(Value *V) const; 348 Value *dyn_castFNegVal(Value *V, bool NoSignedZero = false) const; 349 Type *FindElementAtOffset(PointerType *PtrTy, int64_t Offset, 350 SmallVectorImpl<Value *> &NewIndices); 351 Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI); 352 353 /// \brief Classify whether a cast is worth optimizing. 354 /// 355 /// Returns true if the cast from "V to Ty" actually results in any code 356 /// being generated and is interesting to optimize out. If the cast can be 357 /// eliminated by some other simple transformation, we prefer to do the 358 /// simplification first. 359 bool ShouldOptimizeCast(Instruction::CastOps opcode, const Value *V, 360 Type *Ty); 361 362 /// \brief Try to optimize a sequence of instructions checking if an operation 363 /// on LHS and RHS overflows. 364 /// 365 /// If this overflow check is done via one of the overflow check intrinsics, 366 /// then CtxI has to be the call instruction calling that intrinsic. If this 367 /// overflow check is done by arithmetic followed by a compare, then CtxI has 368 /// to be the arithmetic instruction. 369 /// 370 /// If a simplification is possible, stores the simplified result of the 371 /// operation in OperationResult and result of the overflow check in 372 /// OverflowResult, and return true. If no simplification is possible, 373 /// returns false. 374 bool OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS, Value *RHS, 375 Instruction &CtxI, Value *&OperationResult, 376 Constant *&OverflowResult); 377 378 Instruction *visitCallSite(CallSite CS); 379 Instruction *tryOptimizeCall(CallInst *CI); 380 bool transformConstExprCastCall(CallSite CS); 381 Instruction *transformCallThroughTrampoline(CallSite CS, 382 IntrinsicInst *Tramp); 383 Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI, 384 bool DoXform = true); 385 Instruction *transformSExtICmp(ICmpInst *ICI, Instruction &CI); 386 bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS, Instruction &CxtI); 387 bool WillNotOverflowSignedSub(Value *LHS, Value *RHS, Instruction &CxtI); 388 bool WillNotOverflowUnsignedSub(Value *LHS, Value *RHS, Instruction &CxtI); 389 bool WillNotOverflowSignedMul(Value *LHS, Value *RHS, Instruction &CxtI); 390 Value *EmitGEPOffset(User *GEP); 391 Instruction *scalarizePHI(ExtractElementInst &EI, PHINode *PN); 392 Value *EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask); 393 394 public: 395 /// \brief Inserts an instruction \p New before instruction \p Old 396 /// 397 /// Also adds the new instruction to the worklist and returns \p New so that 398 /// it is suitable for use as the return from the visitation patterns. 399 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) { 400 assert(New && !New->getParent() && 401 "New instruction already inserted into a basic block!"); 402 BasicBlock *BB = Old.getParent(); 403 BB->getInstList().insert(Old.getIterator(), New); // Insert inst 404 Worklist.Add(New); 405 return New; 406 } 407 408 /// \brief Same as InsertNewInstBefore, but also sets the debug loc. 409 Instruction *InsertNewInstWith(Instruction *New, Instruction &Old) { 410 New->setDebugLoc(Old.getDebugLoc()); 411 return InsertNewInstBefore(New, Old); 412 } 413 414 /// \brief A combiner-aware RAUW-like routine. 415 /// 416 /// This method is to be used when an instruction is found to be dead, 417 /// replacable with another preexisting expression. Here we add all uses of 418 /// I to the worklist, replace all uses of I with the new value, then return 419 /// I, so that the inst combiner will know that I was modified. 420 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) { 421 // If there are no uses to replace, then we return nullptr to indicate that 422 // no changes were made to the program. 423 if (I.use_empty()) return nullptr; 424 425 Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist. 426 427 // If we are replacing the instruction with itself, this must be in a 428 // segment of unreachable code, so just clobber the instruction. 429 if (&I == V) 430 V = UndefValue::get(I.getType()); 431 432 DEBUG(dbgs() << "IC: Replacing " << I << "\n" 433 << " with " << *V << '\n'); 434 435 I.replaceAllUsesWith(V); 436 return &I; 437 } 438 439 /// Creates a result tuple for an overflow intrinsic \p II with a given 440 /// \p Result and a constant \p Overflow value. 441 Instruction *CreateOverflowTuple(IntrinsicInst *II, Value *Result, 442 Constant *Overflow) { 443 Constant *V[] = {UndefValue::get(Result->getType()), Overflow}; 444 StructType *ST = cast<StructType>(II->getType()); 445 Constant *Struct = ConstantStruct::get(ST, V); 446 return InsertValueInst::Create(Struct, Result, 0); 447 } 448 449 /// \brief Combiner aware instruction erasure. 450 /// 451 /// When dealing with an instruction that has side effects or produces a void 452 /// value, we can't rely on DCE to delete the instruction. Instead, visit 453 /// methods should return the value returned by this function. 454 Instruction *EraseInstFromFunction(Instruction &I) { 455 DEBUG(dbgs() << "IC: ERASE " << I << '\n'); 456 457 assert(I.use_empty() && "Cannot erase instruction that is used!"); 458 // Make sure that we reprocess all operands now that we reduced their 459 // use counts. 460 if (I.getNumOperands() < 8) { 461 for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i) 462 if (Instruction *Op = dyn_cast<Instruction>(*i)) 463 Worklist.Add(Op); 464 } 465 Worklist.Remove(&I); 466 I.eraseFromParent(); 467 MadeIRChange = true; 468 return nullptr; // Don't do anything with FI 469 } 470 471 void computeKnownBits(Value *V, APInt &KnownZero, APInt &KnownOne, 472 unsigned Depth, Instruction *CxtI) const { 473 return llvm::computeKnownBits(V, KnownZero, KnownOne, DL, Depth, AC, CxtI, 474 DT); 475 } 476 477 bool MaskedValueIsZero(Value *V, const APInt &Mask, unsigned Depth = 0, 478 Instruction *CxtI = nullptr) const { 479 return llvm::MaskedValueIsZero(V, Mask, DL, Depth, AC, CxtI, DT); 480 } 481 unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0, 482 Instruction *CxtI = nullptr) const { 483 return llvm::ComputeNumSignBits(Op, DL, Depth, AC, CxtI, DT); 484 } 485 void ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne, 486 unsigned Depth = 0, Instruction *CxtI = nullptr) const { 487 return llvm::ComputeSignBit(V, KnownZero, KnownOne, DL, Depth, AC, CxtI, 488 DT); 489 } 490 OverflowResult computeOverflowForUnsignedMul(Value *LHS, Value *RHS, 491 const Instruction *CxtI) { 492 return llvm::computeOverflowForUnsignedMul(LHS, RHS, DL, AC, CxtI, DT); 493 } 494 OverflowResult computeOverflowForUnsignedAdd(Value *LHS, Value *RHS, 495 const Instruction *CxtI) { 496 return llvm::computeOverflowForUnsignedAdd(LHS, RHS, DL, AC, CxtI, DT); 497 } 498 499 private: 500 /// \brief Performs a few simplifications for operators which are associative 501 /// or commutative. 502 bool SimplifyAssociativeOrCommutative(BinaryOperator &I); 503 504 /// \brief Tries to simplify binary operations which some other binary 505 /// operation distributes over. 506 /// 507 /// It does this by either by factorizing out common terms (eg "(A*B)+(A*C)" 508 /// -> "A*(B+C)") or expanding out if this results in simplifications (eg: "A 509 /// & (B | C) -> (A&B) | (A&C)" if this is a win). Returns the simplified 510 /// value, or null if it didn't simplify. 511 Value *SimplifyUsingDistributiveLaws(BinaryOperator &I); 512 513 /// \brief Attempts to replace V with a simpler value based on the demanded 514 /// bits. 515 Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask, APInt &KnownZero, 516 APInt &KnownOne, unsigned Depth, 517 Instruction *CxtI); 518 bool SimplifyDemandedBits(Use &U, APInt DemandedMask, APInt &KnownZero, 519 APInt &KnownOne, unsigned Depth = 0); 520 /// Helper routine of SimplifyDemandedUseBits. It tries to simplify demanded 521 /// bit for "r1 = shr x, c1; r2 = shl r1, c2" instruction sequence. 522 Value *SimplifyShrShlDemandedBits(Instruction *Lsr, Instruction *Sftl, 523 APInt DemandedMask, APInt &KnownZero, 524 APInt &KnownOne); 525 526 /// \brief Tries to simplify operands to an integer instruction based on its 527 /// demanded bits. 528 bool SimplifyDemandedInstructionBits(Instruction &Inst); 529 530 Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts, 531 APInt &UndefElts, unsigned Depth = 0); 532 533 Value *SimplifyVectorOp(BinaryOperator &Inst); 534 Value *SimplifyBSwap(BinaryOperator &Inst); 535 536 // FoldOpIntoPhi - Given a binary operator, cast instruction, or select 537 // which has a PHI node as operand #0, see if we can fold the instruction 538 // into the PHI (which is only possible if all operands to the PHI are 539 // constants). 540 // 541 Instruction *FoldOpIntoPhi(Instruction &I); 542 543 /// \brief Try to rotate an operation below a PHI node, using PHI nodes for 544 /// its operands. 545 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN); 546 Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN); 547 Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN); 548 Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN); 549 Instruction *FoldPHIArgZextsIntoPHI(PHINode &PN); 550 551 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS, 552 ConstantInt *AndRHS, BinaryOperator &TheAnd); 553 554 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask, 555 bool isSub, Instruction &I); 556 Value *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, bool isSigned, 557 bool Inside); 558 Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI); 559 Instruction *MatchBSwapOrBitReverse(BinaryOperator &I); 560 bool SimplifyStoreAtEndOfBlock(StoreInst &SI); 561 Instruction *SimplifyMemTransfer(MemIntrinsic *MI); 562 Instruction *SimplifyMemSet(MemSetInst *MI); 563 564 Value *EvaluateInDifferentType(Value *V, Type *Ty, bool isSigned); 565 566 /// \brief Returns a value X such that Val = X * Scale, or null if none. 567 /// 568 /// If the multiplication is known not to overflow then NoSignedWrap is set. 569 Value *Descale(Value *Val, APInt Scale, bool &NoSignedWrap); 570 }; 571 572 } // end namespace llvm. 573 574 #undef DEBUG_TYPE 575 576 #endif 577
