ScalarEvolutionExpander.h

//===---- llvm/Analysis/ScalarEvolutionExpander.h - SCEV Exprs --*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the classes used to generate code from scalar expressions.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H

#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/Support/TargetFolder.h"
#include <set>

namespace llvm {
  class SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
    ScalarEvolution &SE;
    std::map<std::pair<const SCEV *, Instruction *>, AssertingVH<Value> >
      InsertedExpressions;
    std::set<Value*> InsertedValues;

    const Loop *PostIncLoop;

    const Loop *IVIncInsertLoop;

    Instruction *IVIncInsertPos;

    bool CanonicalMode;

    typedef IRBuilder<true, TargetFolder> BuilderType;
    BuilderType Builder;

    friend struct SCEVVisitor<SCEVExpander, Value*>;

  public:
    explicit SCEVExpander(ScalarEvolution &se)
      : SE(se), PostIncLoop(0), IVIncInsertLoop(0), CanonicalMode(true),
        Builder(se.getContext(), TargetFolder(se.TD)) {}

    void clear() { InsertedExpressions.clear(); }

    Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty);

    Value *expandCodeFor(const SCEV *SH, const Type *Ty, Instruction *I) {
      BasicBlock::iterator IP = I;
      while (isInsertedInstruction(IP)) ++IP;
      Builder.SetInsertPoint(IP->getParent(), IP);
      return expandCodeFor(SH, Ty);
    }

    void setIVIncInsertPos(const Loop *L, Instruction *Pos) {
      assert(!CanonicalMode &&
             "IV increment positions are not supported in CanonicalMode");
      IVIncInsertLoop = L;
      IVIncInsertPos = Pos;
    }

    void setPostInc(const Loop *L) {
      assert(!CanonicalMode &&
             "Post-inc expansion is not supported in CanonicalMode");
      PostIncLoop = L;
    }

    void disableCanonicalMode() { CanonicalMode = false; }

  private:
    LLVMContext &getContext() const { return SE.getContext(); }

    Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS);

    Value *InsertNoopCastOfTo(Value *V, const Type *Ty);

    Value *expandAddToGEP(const SCEV *const *op_begin,
                          const SCEV *const *op_end,
                          const PointerType *PTy, const Type *Ty, Value *V);

    Value *expand(const SCEV *S);

    Value *expandCodeFor(const SCEV *SH, const Type *Ty = 0);

    bool isInsertedInstruction(Instruction *I) const {
      return InsertedValues.count(I);
    }

    Value *visitConstant(const SCEVConstant *S) {
      return S->getValue();
    }

    Value *visitTruncateExpr(const SCEVTruncateExpr *S);

    Value *visitZeroExtendExpr(const SCEVZeroExtendExpr *S);

    Value *visitSignExtendExpr(const SCEVSignExtendExpr *S);

    Value *visitAddExpr(const SCEVAddExpr *S);

    Value *visitMulExpr(const SCEVMulExpr *S);

    Value *visitUDivExpr(const SCEVUDivExpr *S);

    Value *visitAddRecExpr(const SCEVAddRecExpr *S);

    Value *visitSMaxExpr(const SCEVSMaxExpr *S);

    Value *visitUMaxExpr(const SCEVUMaxExpr *S);

    Value *visitUnknown(const SCEVUnknown *S) {
      return S->getValue();
    }

    void rememberInstruction(Value *I);

    void restoreInsertPoint(BasicBlock *BB, BasicBlock::iterator I);

    Value *expandAddRecExprLiterally(const SCEVAddRecExpr *);
    PHINode *getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
                                       const Loop *L,
                                       const Type *ExpandTy,
                                       const Type *IntTy);
  };
}

#endif

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