1 //===- InstCombine.h - Main InstCombine pass definition -------------------===// 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 10 #ifndef INSTCOMBINE_INSTCOMBINE_H 11 #define INSTCOMBINE_INSTCOMBINE_H 12 13 #include "InstCombineWorklist.h" 14 #include "llvm/IntrinsicInst.h" 15 #include "llvm/Operator.h" 16 #include "llvm/Pass.h" 17 #include "llvm/Analysis/ValueTracking.h" 18 #include "llvm/Support/IRBuilder.h" 19 #include "llvm/Support/InstVisitor.h" 20 #include "llvm/Support/TargetFolder.h" 21 22 namespace llvm { 23 class CallSite; 24 class TargetData; 25 class DbgDeclareInst; 26 class MemIntrinsic; 27 class MemSetInst; 28 29 /// SelectPatternFlavor - We can match a variety of different patterns for 30 /// select operations. 31 enum SelectPatternFlavor { 32 SPF_UNKNOWN = 0, 33 SPF_SMIN, SPF_UMIN, 34 SPF_SMAX, SPF_UMAX 35 //SPF_ABS - TODO. 36 }; 37 38 /// getComplexity: Assign a complexity or rank value to LLVM Values... 39 /// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst 40 static inline unsigned getComplexity(Value *V) { 41 if (isa<Instruction>(V)) { 42 if (BinaryOperator::isNeg(V) || 43 BinaryOperator::isFNeg(V) || 44 BinaryOperator::isNot(V)) 45 return 3; 46 return 4; 47 } 48 if (isa<Argument>(V)) return 3; 49 return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2; 50 } 51 52 53 /// InstCombineIRInserter - This is an IRBuilder insertion helper that works 54 /// just like the normal insertion helper, but also adds any new instructions 55 /// to the instcombine worklist. 56 class LLVM_LIBRARY_VISIBILITY InstCombineIRInserter 57 : public IRBuilderDefaultInserter<true> { 58 InstCombineWorklist &Worklist; 59 public: 60 InstCombineIRInserter(InstCombineWorklist &WL) : Worklist(WL) {} 61 62 void InsertHelper(Instruction *I, const Twine &Name, 63 BasicBlock *BB, BasicBlock::iterator InsertPt) const { 64 IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt); 65 Worklist.Add(I); 66 } 67 }; 68 69 /// InstCombiner - The -instcombine pass. 70 class LLVM_LIBRARY_VISIBILITY InstCombiner 71 : public FunctionPass, 72 public InstVisitor<InstCombiner, Instruction*> { 73 TargetData *TD; 74 bool MadeIRChange; 75 public: 76 /// Worklist - All of the instructions that need to be simplified. 77 InstCombineWorklist Worklist; 78 79 /// Builder - This is an IRBuilder that automatically inserts new 80 /// instructions into the worklist when they are created. 81 typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy; 82 BuilderTy *Builder; 83 84 static char ID; // Pass identification, replacement for typeid 85 InstCombiner() : FunctionPass(ID), TD(0), Builder(0) { 86 initializeInstCombinerPass(*PassRegistry::getPassRegistry()); 87 } 88 89 public: 90 virtual bool runOnFunction(Function &F); 91 92 bool DoOneIteration(Function &F, unsigned ItNum); 93 94 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 95 96 TargetData *getTargetData() const { return TD; } 97 98 // Visitation implementation - Implement instruction combining for different 99 // instruction types. The semantics are as follows: 100 // Return Value: 101 // null - No change was made 102 // I - Change was made, I is still valid, I may be dead though 103 // otherwise - Change was made, replace I with returned instruction 104 // 105 Instruction *visitAdd(BinaryOperator &I); 106 Instruction *visitFAdd(BinaryOperator &I); 107 Value *OptimizePointerDifference(Value *LHS, Value *RHS, Type *Ty); 108 Instruction *visitSub(BinaryOperator &I); 109 Instruction *visitFSub(BinaryOperator &I); 110 Instruction *visitMul(BinaryOperator &I); 111 Instruction *visitFMul(BinaryOperator &I); 112 Instruction *visitURem(BinaryOperator &I); 113 Instruction *visitSRem(BinaryOperator &I); 114 Instruction *visitFRem(BinaryOperator &I); 115 bool SimplifyDivRemOfSelect(BinaryOperator &I); 116 Instruction *commonRemTransforms(BinaryOperator &I); 117 Instruction *commonIRemTransforms(BinaryOperator &I); 118 Instruction *commonDivTransforms(BinaryOperator &I); 119 Instruction *commonIDivTransforms(BinaryOperator &I); 120 Instruction *visitUDiv(BinaryOperator &I); 121 Instruction *visitSDiv(BinaryOperator &I); 122 Instruction *visitFDiv(BinaryOperator &I); 123 Value *FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS); 124 Value *FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS); 125 Instruction *visitAnd(BinaryOperator &I); 126 Value *FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS); 127 Value *FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS); 128 Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op, 129 Value *A, Value *B, Value *C); 130 Instruction *visitOr (BinaryOperator &I); 131 Instruction *visitXor(BinaryOperator &I); 132 Instruction *visitShl(BinaryOperator &I); 133 Instruction *visitAShr(BinaryOperator &I); 134 Instruction *visitLShr(BinaryOperator &I); 135 Instruction *commonShiftTransforms(BinaryOperator &I); 136 Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI, 137 Constant *RHSC); 138 Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, 139 GlobalVariable *GV, CmpInst &ICI, 140 ConstantInt *AndCst = 0); 141 Instruction *visitFCmpInst(FCmpInst &I); 142 Instruction *visitICmpInst(ICmpInst &I); 143 Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI); 144 Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI, 145 Instruction *LHS, 146 ConstantInt *RHS); 147 Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI, 148 ConstantInt *DivRHS); 149 Instruction *FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *DivI, 150 ConstantInt *DivRHS); 151 Instruction *FoldICmpAddOpCst(ICmpInst &ICI, Value *X, ConstantInt *CI, 152 ICmpInst::Predicate Pred, Value *TheAdd); 153 Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, 154 ICmpInst::Predicate Cond, Instruction &I); 155 Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1, 156 BinaryOperator &I); 157 Instruction *commonCastTransforms(CastInst &CI); 158 Instruction *commonPointerCastTransforms(CastInst &CI); 159 Instruction *visitTrunc(TruncInst &CI); 160 Instruction *visitZExt(ZExtInst &CI); 161 Instruction *visitSExt(SExtInst &CI); 162 Instruction *visitFPTrunc(FPTruncInst &CI); 163 Instruction *visitFPExt(CastInst &CI); 164 Instruction *visitFPToUI(FPToUIInst &FI); 165 Instruction *visitFPToSI(FPToSIInst &FI); 166 Instruction *visitUIToFP(CastInst &CI); 167 Instruction *visitSIToFP(CastInst &CI); 168 Instruction *visitPtrToInt(PtrToIntInst &CI); 169 Instruction *visitIntToPtr(IntToPtrInst &CI); 170 Instruction *visitBitCast(BitCastInst &CI); 171 Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI, 172 Instruction *FI); 173 Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*); 174 Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1, 175 Value *A, Value *B, Instruction &Outer, 176 SelectPatternFlavor SPF2, Value *C); 177 Instruction *visitSelectInst(SelectInst &SI); 178 Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI); 179 Instruction *visitCallInst(CallInst &CI); 180 Instruction *visitInvokeInst(InvokeInst &II); 181 182 Instruction *SliceUpIllegalIntegerPHI(PHINode &PN); 183 Instruction *visitPHINode(PHINode &PN); 184 Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP); 185 Instruction *visitAllocaInst(AllocaInst &AI); 186 Instruction *visitMalloc(Instruction &FI); 187 Instruction *visitFree(CallInst &FI); 188 Instruction *visitLoadInst(LoadInst &LI); 189 Instruction *visitStoreInst(StoreInst &SI); 190 Instruction *visitBranchInst(BranchInst &BI); 191 Instruction *visitSwitchInst(SwitchInst &SI); 192 Instruction *visitInsertElementInst(InsertElementInst &IE); 193 Instruction *visitExtractElementInst(ExtractElementInst &EI); 194 Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI); 195 Instruction *visitExtractValueInst(ExtractValueInst &EV); 196 Instruction *visitLandingPadInst(LandingPadInst &LI); 197 198 // visitInstruction - Specify what to return for unhandled instructions... 199 Instruction *visitInstruction(Instruction &I) { return 0; } 200 201 private: 202 bool ShouldChangeType(Type *From, Type *To) const; 203 Value *dyn_castNegVal(Value *V) const; 204 Value *dyn_castFNegVal(Value *V) const; 205 Type *FindElementAtOffset(Type *Ty, int64_t Offset, 206 SmallVectorImpl<Value*> &NewIndices); 207 Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI); 208 209 /// ShouldOptimizeCast - Return true if the cast from "V to Ty" actually 210 /// results in any code being generated and is interesting to optimize out. If 211 /// the cast can be eliminated by some other simple transformation, we prefer 212 /// to do the simplification first. 213 bool ShouldOptimizeCast(Instruction::CastOps opcode,const Value *V, 214 Type *Ty); 215 216 Instruction *visitCallSite(CallSite CS); 217 Instruction *tryOptimizeCall(CallInst *CI, const TargetData *TD); 218 bool transformConstExprCastCall(CallSite CS); 219 Instruction *transformCallThroughTrampoline(CallSite CS, 220 IntrinsicInst *Tramp); 221 Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI, 222 bool DoXform = true); 223 Instruction *transformSExtICmp(ICmpInst *ICI, Instruction &CI); 224 bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS); 225 Value *EmitGEPOffset(User *GEP); 226 227 public: 228 // InsertNewInstBefore - insert an instruction New before instruction Old 229 // in the program. Add the new instruction to the worklist. 230 // 231 Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) { 232 assert(New && New->getParent() == 0 && 233 "New instruction already inserted into a basic block!"); 234 BasicBlock *BB = Old.getParent(); 235 BB->getInstList().insert(&Old, New); // Insert inst 236 Worklist.Add(New); 237 return New; 238 } 239 240 // InsertNewInstWith - same as InsertNewInstBefore, but also sets the 241 // debug loc. 242 // 243 Instruction *InsertNewInstWith(Instruction *New, Instruction &Old) { 244 New->setDebugLoc(Old.getDebugLoc()); 245 return InsertNewInstBefore(New, Old); 246 } 247 248 // ReplaceInstUsesWith - This method is to be used when an instruction is 249 // found to be dead, replacable with another preexisting expression. Here 250 // we add all uses of I to the worklist, replace all uses of I with the new 251 // value, then return I, so that the inst combiner will know that I was 252 // modified. 253 // 254 Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) { 255 Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist. 256 257 // If we are replacing the instruction with itself, this must be in a 258 // segment of unreachable code, so just clobber the instruction. 259 if (&I == V) 260 V = UndefValue::get(I.getType()); 261 262 DEBUG(errs() << "IC: Replacing " << I << "\n" 263 " with " << *V << '\n'); 264 265 I.replaceAllUsesWith(V); 266 return &I; 267 } 268 269 // EraseInstFromFunction - When dealing with an instruction that has side 270 // effects or produces a void value, we can't rely on DCE to delete the 271 // instruction. Instead, visit methods should return the value returned by 272 // this function. 273 Instruction *EraseInstFromFunction(Instruction &I) { 274 DEBUG(errs() << "IC: ERASE " << I << '\n'); 275 276 assert(I.use_empty() && "Cannot erase instruction that is used!"); 277 // Make sure that we reprocess all operands now that we reduced their 278 // use counts. 279 if (I.getNumOperands() < 8) { 280 for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i) 281 if (Instruction *Op = dyn_cast<Instruction>(*i)) 282 Worklist.Add(Op); 283 } 284 Worklist.Remove(&I); 285 I.eraseFromParent(); 286 MadeIRChange = true; 287 return 0; // Don't do anything with FI 288 } 289 290 void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero, 291 APInt &KnownOne, unsigned Depth = 0) const { 292 return llvm::ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth); 293 } 294 295 bool MaskedValueIsZero(Value *V, const APInt &Mask, 296 unsigned Depth = 0) const { 297 return llvm::MaskedValueIsZero(V, Mask, TD, Depth); 298 } 299 unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const { 300 return llvm::ComputeNumSignBits(Op, TD, Depth); 301 } 302 303 private: 304 305 /// SimplifyAssociativeOrCommutative - This performs a few simplifications for 306 /// operators which are associative or commutative. 307 bool SimplifyAssociativeOrCommutative(BinaryOperator &I); 308 309 /// SimplifyUsingDistributiveLaws - This tries to simplify binary operations 310 /// which some other binary operation distributes over either by factorizing 311 /// out common terms (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this 312 /// results in simplifications (eg: "A & (B | C) -> (A&B) | (A&C)" if this is 313 /// a win). Returns the simplified value, or null if it didn't simplify. 314 Value *SimplifyUsingDistributiveLaws(BinaryOperator &I); 315 316 /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value 317 /// based on the demanded bits. 318 Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask, 319 APInt& KnownZero, APInt& KnownOne, 320 unsigned Depth); 321 bool SimplifyDemandedBits(Use &U, APInt DemandedMask, 322 APInt& KnownZero, APInt& KnownOne, 323 unsigned Depth=0); 324 325 /// SimplifyDemandedInstructionBits - Inst is an integer instruction that 326 /// SimplifyDemandedBits knows about. See if the instruction has any 327 /// properties that allow us to simplify its operands. 328 bool SimplifyDemandedInstructionBits(Instruction &Inst); 329 330 Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts, 331 APInt& UndefElts, unsigned Depth = 0); 332 333 // FoldOpIntoPhi - Given a binary operator, cast instruction, or select 334 // which has a PHI node as operand #0, see if we can fold the instruction 335 // into the PHI (which is only possible if all operands to the PHI are 336 // constants). 337 // 338 Instruction *FoldOpIntoPhi(Instruction &I); 339 340 // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary" 341 // operator and they all are only used by the PHI, PHI together their 342 // inputs, and do the operation once, to the result of the PHI. 343 Instruction *FoldPHIArgOpIntoPHI(PHINode &PN); 344 Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN); 345 Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN); 346 Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN); 347 348 349 Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS, 350 ConstantInt *AndRHS, BinaryOperator &TheAnd); 351 352 Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask, 353 bool isSub, Instruction &I); 354 Value *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, 355 bool isSigned, bool Inside); 356 Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI); 357 Instruction *MatchBSwap(BinaryOperator &I); 358 bool SimplifyStoreAtEndOfBlock(StoreInst &SI); 359 Instruction *SimplifyMemTransfer(MemIntrinsic *MI); 360 Instruction *SimplifyMemSet(MemSetInst *MI); 361 362 363 Value *EvaluateInDifferentType(Value *V, Type *Ty, bool isSigned); 364 }; 365 366 367 368 } // end namespace llvm. 369 370 #endif 371
