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