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			375 lines
		
	
	
		
			16 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			375 lines
		
	
	
		
			16 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| //===- InstCombine.h - Main InstCombine pass definition -------------------===//
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| //
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| //                     The LLVM Compiler Infrastructure
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| //
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| // This file is distributed under the University of Illinois Open Source
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| // License. See LICENSE.TXT for details.
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| //
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| //===----------------------------------------------------------------------===//
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| 
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| #ifndef INSTCOMBINE_INSTCOMBINE_H
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| #define INSTCOMBINE_INSTCOMBINE_H
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| 
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| #include "InstCombineWorklist.h"
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| #include "llvm/IntrinsicInst.h"
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| #include "llvm/Operator.h"
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| #include "llvm/Pass.h"
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| #include "llvm/Analysis/ValueTracking.h"
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| #include "llvm/Support/IRBuilder.h"
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| #include "llvm/Support/InstVisitor.h"
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| #include "llvm/Support/TargetFolder.h"
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| 
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| namespace llvm {
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|   class CallSite;
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|   class TargetData;
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|   class TargetLibraryInfo;
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|   class DbgDeclareInst;
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|   class MemIntrinsic;
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|   class MemSetInst;
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|   
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| /// SelectPatternFlavor - We can match a variety of different patterns for
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| /// select operations.
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| enum SelectPatternFlavor {
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|   SPF_UNKNOWN = 0,
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|   SPF_SMIN, SPF_UMIN,
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|   SPF_SMAX, SPF_UMAX
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|   //SPF_ABS - TODO.
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| };
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|   
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| /// getComplexity:  Assign a complexity or rank value to LLVM Values...
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| ///   0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
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| static inline unsigned getComplexity(Value *V) {
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|   if (isa<Instruction>(V)) {
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|     if (BinaryOperator::isNeg(V) ||
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|         BinaryOperator::isFNeg(V) ||
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|         BinaryOperator::isNot(V))
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|       return 3;
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|     return 4;
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|   }
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|   if (isa<Argument>(V)) return 3;
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|   return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
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| }
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| 
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|   
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| /// InstCombineIRInserter - This is an IRBuilder insertion helper that works
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| /// just like the normal insertion helper, but also adds any new instructions
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| /// to the instcombine worklist.
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| class LLVM_LIBRARY_VISIBILITY InstCombineIRInserter 
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|     : public IRBuilderDefaultInserter<true> {
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|   InstCombineWorklist &Worklist;
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| public:
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|   InstCombineIRInserter(InstCombineWorklist &WL) : Worklist(WL) {}
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|   
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|   void InsertHelper(Instruction *I, const Twine &Name,
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|                     BasicBlock *BB, BasicBlock::iterator InsertPt) const {
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|     IRBuilderDefaultInserter<true>::InsertHelper(I, Name, BB, InsertPt);
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|     Worklist.Add(I);
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|   }
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| };
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|   
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| /// InstCombiner - The -instcombine pass.
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| class LLVM_LIBRARY_VISIBILITY InstCombiner
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|                              : public FunctionPass,
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|                                public InstVisitor<InstCombiner, Instruction*> {
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|   TargetData *TD;
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|   TargetLibraryInfo *TLI;
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|   bool MadeIRChange;
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| public:
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|   /// Worklist - All of the instructions that need to be simplified.
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|   InstCombineWorklist Worklist;
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| 
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|   /// Builder - This is an IRBuilder that automatically inserts new
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|   /// instructions into the worklist when they are created.
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|   typedef IRBuilder<true, TargetFolder, InstCombineIRInserter> BuilderTy;
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|   BuilderTy *Builder;
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|       
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|   static char ID; // Pass identification, replacement for typeid
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|   InstCombiner() : FunctionPass(ID), TD(0), Builder(0) {
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|     initializeInstCombinerPass(*PassRegistry::getPassRegistry());
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|   }
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| 
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| public:
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|   virtual bool runOnFunction(Function &F);
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|   
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|   bool DoOneIteration(Function &F, unsigned ItNum);
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| 
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|   virtual void getAnalysisUsage(AnalysisUsage &AU) const;
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| 
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|   TargetData *getTargetData() const { return TD; }
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| 
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|   TargetLibraryInfo *getTargetLibraryInfo() const { return TLI; }
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| 
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|   // Visitation implementation - Implement instruction combining for different
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|   // instruction types.  The semantics are as follows:
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|   // Return Value:
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|   //    null        - No change was made
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|   //     I          - Change was made, I is still valid, I may be dead though
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|   //   otherwise    - Change was made, replace I with returned instruction
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|   //
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|   Instruction *visitAdd(BinaryOperator &I);
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|   Instruction *visitFAdd(BinaryOperator &I);
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|   Value *OptimizePointerDifference(Value *LHS, Value *RHS, Type *Ty);
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|   Instruction *visitSub(BinaryOperator &I);
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|   Instruction *visitFSub(BinaryOperator &I);
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|   Instruction *visitMul(BinaryOperator &I);
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|   Instruction *visitFMul(BinaryOperator &I);
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|   Instruction *visitURem(BinaryOperator &I);
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|   Instruction *visitSRem(BinaryOperator &I);
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|   Instruction *visitFRem(BinaryOperator &I);
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|   bool SimplifyDivRemOfSelect(BinaryOperator &I);
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|   Instruction *commonRemTransforms(BinaryOperator &I);
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|   Instruction *commonIRemTransforms(BinaryOperator &I);
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|   Instruction *commonDivTransforms(BinaryOperator &I);
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|   Instruction *commonIDivTransforms(BinaryOperator &I);
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|   Instruction *visitUDiv(BinaryOperator &I);
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|   Instruction *visitSDiv(BinaryOperator &I);
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|   Instruction *visitFDiv(BinaryOperator &I);
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|   Value *FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS);
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|   Value *FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
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|   Instruction *visitAnd(BinaryOperator &I);
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|   Value *FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS);
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|   Value *FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS);
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|   Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op,
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|                                    Value *A, Value *B, Value *C);
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|   Instruction *visitOr (BinaryOperator &I);
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|   Instruction *visitXor(BinaryOperator &I);
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|   Instruction *visitShl(BinaryOperator &I);
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|   Instruction *visitAShr(BinaryOperator &I);
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|   Instruction *visitLShr(BinaryOperator &I);
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|   Instruction *commonShiftTransforms(BinaryOperator &I);
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|   Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
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|                                     Constant *RHSC);
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|   Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
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|                                             GlobalVariable *GV, CmpInst &ICI,
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|                                             ConstantInt *AndCst = 0);
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|   Instruction *visitFCmpInst(FCmpInst &I);
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|   Instruction *visitICmpInst(ICmpInst &I);
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|   Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
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|   Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
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|                                               Instruction *LHS,
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|                                               ConstantInt *RHS);
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|   Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
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|                               ConstantInt *DivRHS);
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|   Instruction *FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *DivI,
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|                               ConstantInt *DivRHS);
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|   Instruction *FoldICmpAddOpCst(ICmpInst &ICI, Value *X, ConstantInt *CI,
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|                                 ICmpInst::Predicate Pred, Value *TheAdd);
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|   Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
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|                            ICmpInst::Predicate Cond, Instruction &I);
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|   Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
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|                                    BinaryOperator &I);
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|   Instruction *commonCastTransforms(CastInst &CI);
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|   Instruction *commonPointerCastTransforms(CastInst &CI);
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|   Instruction *visitTrunc(TruncInst &CI);
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|   Instruction *visitZExt(ZExtInst &CI);
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|   Instruction *visitSExt(SExtInst &CI);
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|   Instruction *visitFPTrunc(FPTruncInst &CI);
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|   Instruction *visitFPExt(CastInst &CI);
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|   Instruction *visitFPToUI(FPToUIInst &FI);
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|   Instruction *visitFPToSI(FPToSIInst &FI);
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|   Instruction *visitUIToFP(CastInst &CI);
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|   Instruction *visitSIToFP(CastInst &CI);
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|   Instruction *visitPtrToInt(PtrToIntInst &CI);
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|   Instruction *visitIntToPtr(IntToPtrInst &CI);
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|   Instruction *visitBitCast(BitCastInst &CI);
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|   Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
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|                               Instruction *FI);
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|   Instruction *FoldSelectIntoOp(SelectInst &SI, Value*, Value*);
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|   Instruction *FoldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
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|                             Value *A, Value *B, Instruction &Outer,
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|                             SelectPatternFlavor SPF2, Value *C);
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|   Instruction *visitSelectInst(SelectInst &SI);
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|   Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
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|   Instruction *visitCallInst(CallInst &CI);
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|   Instruction *visitInvokeInst(InvokeInst &II);
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| 
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|   Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
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|   Instruction *visitPHINode(PHINode &PN);
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|   Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
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|   Instruction *visitAllocaInst(AllocaInst &AI);
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|   Instruction *visitMalloc(Instruction &FI);
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|   Instruction *visitFree(CallInst &FI);
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|   Instruction *visitLoadInst(LoadInst &LI);
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|   Instruction *visitStoreInst(StoreInst &SI);
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|   Instruction *visitBranchInst(BranchInst &BI);
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|   Instruction *visitSwitchInst(SwitchInst &SI);
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|   Instruction *visitInsertElementInst(InsertElementInst &IE);
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|   Instruction *visitExtractElementInst(ExtractElementInst &EI);
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|   Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
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|   Instruction *visitExtractValueInst(ExtractValueInst &EV);
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|   Instruction *visitLandingPadInst(LandingPadInst &LI);
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| 
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|   // visitInstruction - Specify what to return for unhandled instructions...
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|   Instruction *visitInstruction(Instruction &I) { return 0; }
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| 
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| private:
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|   bool ShouldChangeType(Type *From, Type *To) const;
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|   Value *dyn_castNegVal(Value *V) const;
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|   Value *dyn_castFNegVal(Value *V) const;
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|   Type *FindElementAtOffset(Type *Ty, int64_t Offset, 
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|                                   SmallVectorImpl<Value*> &NewIndices);
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|   Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI);
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|                                  
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|   /// ShouldOptimizeCast - Return true if the cast from "V to Ty" actually
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|   /// results in any code being generated and is interesting to optimize out. If
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|   /// the cast can be eliminated by some other simple transformation, we prefer
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|   /// to do the simplification first.
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|   bool ShouldOptimizeCast(Instruction::CastOps opcode,const Value *V,
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|                           Type *Ty);
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| 
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|   Instruction *visitCallSite(CallSite CS);
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|   Instruction *tryOptimizeCall(CallInst *CI, const TargetData *TD);
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|   bool transformConstExprCastCall(CallSite CS);
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|   Instruction *transformCallThroughTrampoline(CallSite CS,
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|                                               IntrinsicInst *Tramp);
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|   Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
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|                                  bool DoXform = true);
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|   Instruction *transformSExtICmp(ICmpInst *ICI, Instruction &CI);
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|   bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
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|   Value *EmitGEPOffset(User *GEP);
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| 
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| public:
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|   // InsertNewInstBefore - insert an instruction New before instruction Old
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|   // in the program.  Add the new instruction to the worklist.
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|   //
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|   Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
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|     assert(New && New->getParent() == 0 &&
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|            "New instruction already inserted into a basic block!");
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|     BasicBlock *BB = Old.getParent();
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|     BB->getInstList().insert(&Old, New);  // Insert inst
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|     Worklist.Add(New);
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|     return New;
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|   }
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| 
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|   // InsertNewInstWith - same as InsertNewInstBefore, but also sets the 
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|   // debug loc.
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|   //
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|   Instruction *InsertNewInstWith(Instruction *New, Instruction &Old) {
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|     New->setDebugLoc(Old.getDebugLoc());
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|     return InsertNewInstBefore(New, Old);
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|   }
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| 
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|   // ReplaceInstUsesWith - This method is to be used when an instruction is
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|   // found to be dead, replacable with another preexisting expression.  Here
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|   // we add all uses of I to the worklist, replace all uses of I with the new
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|   // value, then return I, so that the inst combiner will know that I was
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|   // modified.
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|   //
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|   Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
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|     Worklist.AddUsersToWorkList(I);   // Add all modified instrs to worklist.
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|     
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|     // If we are replacing the instruction with itself, this must be in a
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|     // segment of unreachable code, so just clobber the instruction.
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|     if (&I == V) 
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|       V = UndefValue::get(I.getType());
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| 
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|     DEBUG(errs() << "IC: Replacing " << I << "\n"
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|                     "    with " << *V << '\n');
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| 
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|     I.replaceAllUsesWith(V);
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|     return &I;
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|   }
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| 
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|   // EraseInstFromFunction - When dealing with an instruction that has side
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|   // effects or produces a void value, we can't rely on DCE to delete the
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|   // instruction.  Instead, visit methods should return the value returned by
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|   // this function.
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|   Instruction *EraseInstFromFunction(Instruction &I) {
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|     DEBUG(errs() << "IC: ERASE " << I << '\n');
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| 
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|     assert(I.use_empty() && "Cannot erase instruction that is used!");
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|     // Make sure that we reprocess all operands now that we reduced their
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|     // use counts.
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|     if (I.getNumOperands() < 8) {
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|       for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
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|         if (Instruction *Op = dyn_cast<Instruction>(*i))
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|           Worklist.Add(Op);
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|     }
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|     Worklist.Remove(&I);
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|     I.eraseFromParent();
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|     MadeIRChange = true;
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|     return 0;  // Don't do anything with FI
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|   }
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|       
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|   void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
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|                          APInt &KnownOne, unsigned Depth = 0) const {
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|     return llvm::ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth);
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|   }
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|   
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|   bool MaskedValueIsZero(Value *V, const APInt &Mask, 
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|                          unsigned Depth = 0) const {
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|     return llvm::MaskedValueIsZero(V, Mask, TD, Depth);
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|   }
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|   unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const {
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|     return llvm::ComputeNumSignBits(Op, TD, Depth);
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|   }
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| 
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| private:
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| 
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|   /// SimplifyAssociativeOrCommutative - This performs a few simplifications for
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|   /// operators which are associative or commutative.
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|   bool SimplifyAssociativeOrCommutative(BinaryOperator &I);
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| 
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|   /// SimplifyUsingDistributiveLaws - This tries to simplify binary operations
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|   /// which some other binary operation distributes over either by factorizing
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|   /// out common terms (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this
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|   /// results in simplifications (eg: "A & (B | C) -> (A&B) | (A&C)" if this is
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|   /// a win).  Returns the simplified value, or null if it didn't simplify.
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|   Value *SimplifyUsingDistributiveLaws(BinaryOperator &I);
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| 
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|   /// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
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|   /// based on the demanded bits.
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|   Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask, 
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|                                  APInt& KnownZero, APInt& KnownOne,
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|                                  unsigned Depth);
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|   bool SimplifyDemandedBits(Use &U, APInt DemandedMask, 
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|                             APInt& KnownZero, APInt& KnownOne,
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|                             unsigned Depth=0);
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|       
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|   /// SimplifyDemandedInstructionBits - Inst is an integer instruction that
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|   /// SimplifyDemandedBits knows about.  See if the instruction has any
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|   /// properties that allow us to simplify its operands.
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|   bool SimplifyDemandedInstructionBits(Instruction &Inst);
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|       
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|   Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
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|                                     APInt& UndefElts, unsigned Depth = 0);
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|     
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|   // FoldOpIntoPhi - Given a binary operator, cast instruction, or select
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|   // which has a PHI node as operand #0, see if we can fold the instruction
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|   // into the PHI (which is only possible if all operands to the PHI are
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|   // constants).
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|   //
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|   Instruction *FoldOpIntoPhi(Instruction &I);
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| 
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|   // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
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|   // operator and they all are only used by the PHI, PHI together their
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|   // inputs, and do the operation once, to the result of the PHI.
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|   Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
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|   Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
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|   Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
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|   Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
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| 
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|   
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|   Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
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|                         ConstantInt *AndRHS, BinaryOperator &TheAnd);
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|   
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|   Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
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|                             bool isSub, Instruction &I);
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|   Value *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
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|                          bool isSigned, bool Inside);
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|   Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
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|   Instruction *MatchBSwap(BinaryOperator &I);
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|   bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
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|   Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
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|   Instruction *SimplifyMemSet(MemSetInst *MI);
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| 
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| 
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|   Value *EvaluateInDifferentType(Value *V, Type *Ty, bool isSigned);
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| };
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| 
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|       
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|   
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| } // end namespace llvm.
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| 
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| #endif
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