ScalarEvolutionExpander.h revision 6177fd4fcee4d82692c47e33754ffe285c38cc69
1//===---- llvm/Analysis/ScalarEvolutionExpander.h - SCEV Exprs --*- 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// 10// This file defines the classes used to generate code from scalar expressions. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H 15#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H 16 17#include "llvm/Instructions.h" 18#include "llvm/Type.h" 19#include "llvm/Analysis/ScalarEvolution.h" 20#include "llvm/Analysis/ScalarEvolutionExpressions.h" 21 22namespace llvm { 23 /// SCEVExpander - This class uses information about analyze scalars to 24 /// rewrite expressions in canonical form. 25 /// 26 /// Clients should create an instance of this class when rewriting is needed, 27 /// and destroy it when finished to allow the release of the associated 28 /// memory. 29 struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> { 30 ScalarEvolution &SE; 31 LoopInfo &LI; 32 std::map<SCEVHandle, Value*> InsertedExpressions; 33 std::set<Instruction*> InsertedInstructions; 34 35 Instruction *InsertPt; 36 37 friend struct SCEVVisitor<SCEVExpander, Value*>; 38 public: 39 SCEVExpander(ScalarEvolution &se, LoopInfo &li) : SE(se), LI(li) {} 40 41 LoopInfo &getLoopInfo() const { return LI; } 42 43 /// clear - Erase the contents of the InsertedExpressions map so that users 44 /// trying to expand the same expression into multiple BasicBlocks or 45 /// different places within the same BasicBlock can do so. 46 void clear() { InsertedExpressions.clear(); } 47 48 /// isInsertedInstruction - Return true if the specified instruction was 49 /// inserted by the code rewriter. If so, the client should not modify the 50 /// instruction. 51 bool isInsertedInstruction(Instruction *I) const { 52 return InsertedInstructions.count(I); 53 } 54 55 /// getOrInsertCanonicalInductionVariable - This method returns the 56 /// canonical induction variable of the specified type for the specified 57 /// loop (inserting one if there is none). A canonical induction variable 58 /// starts at zero and steps by one on each iteration. 59 Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty){ 60 assert(Ty->isInteger() && "Can only insert integer induction variables!"); 61 SCEVHandle H = SE.getAddRecExpr(SE.getIntegerSCEV(0, Ty), 62 SE.getIntegerSCEV(1, Ty), L); 63 return expand(H); 64 } 65 66 /// addInsertedValue - Remember the specified instruction as being the 67 /// canonical form for the specified SCEV. 68 void addInsertedValue(Instruction *I, SCEV *S) { 69 InsertedExpressions[S] = (Value*)I; 70 InsertedInstructions.insert(I); 71 } 72 73 Instruction *getInsertionPoint() const { return InsertPt; } 74 75 /// expandCodeFor - Insert code to directly compute the specified SCEV 76 /// expression into the program. The inserted code is inserted into the 77 /// specified block. 78 Value *expandCodeFor(SCEVHandle SH, Instruction *IP); 79 80 /// InsertCastOfTo - Insert a cast of V to the specified type, doing what 81 /// we can to share the casts. 82 static Value *InsertCastOfTo(Instruction::CastOps opcode, Value *V, 83 const Type *Ty); 84 /// InsertBinop - Insert the specified binary operator, doing a small amount 85 /// of work to avoid inserting an obviously redundant operation. 86 static Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, 87 Value *RHS, Instruction *InsertPt); 88 protected: 89 Value *expand(SCEV *S); 90 91 Value *visitConstant(SCEVConstant *S) { 92 return S->getValue(); 93 } 94 95 Value *visitTruncateExpr(SCEVTruncateExpr *S); 96 97 Value *visitZeroExtendExpr(SCEVZeroExtendExpr *S); 98 99 Value *visitSignExtendExpr(SCEVSignExtendExpr *S); 100 101 Value *visitAddExpr(SCEVAddExpr *S); 102 103 Value *visitMulExpr(SCEVMulExpr *S); 104 105 Value *visitUDivExpr(SCEVUDivExpr *S); 106 107 Value *visitAddRecExpr(SCEVAddRecExpr *S); 108 109 Value *visitSMaxExpr(SCEVSMaxExpr *S); 110 111 Value *visitUMaxExpr(SCEVUMaxExpr *S); 112 113 Value *visitUnknown(SCEVUnknown *S) { 114 return S->getValue(); 115 } 116 }; 117} 118 119#endif 120 121