llvm-6502/include/llvm/Analysis/ScalarEvolutionExpander.h
2006-02-04 09:51:33 +00:00

156 lines
5.4 KiB
C++

//===---- llvm/Analysis/ScalarEvolutionExpander.h - SCEV Exprs --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and 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/BasicBlock.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Support/CFG.h"
namespace llvm {
/// SCEVExpander - This class uses information about analyze scalars to
/// rewrite expressions in canonical form.
///
/// Clients should create an instance of this class when rewriting is needed,
/// and destroying it when finished to allow the release of the associated
/// memory.
struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
ScalarEvolution &SE;
LoopInfo &LI;
std::map<SCEVHandle, Value*> InsertedExpressions;
std::set<Instruction*> InsertedInstructions;
Instruction *InsertPt;
friend struct SCEVVisitor<SCEVExpander, Value*>;
public:
SCEVExpander(ScalarEvolution &se, LoopInfo &li) : SE(se), LI(li) {}
LoopInfo &getLoopInfo() const { return LI; }
/// clear - Erase the contents of the InsertedExpressions map so that users
/// trying to expand the same expression into multiple BasicBlocks or
/// different places within the same BasicBlock can do so.
void clear() { InsertedExpressions.clear(); }
/// isInsertedInstruction - Return true if the specified instruction was
/// inserted by the code rewriter. If so, the client should not modify the
/// instruction.
bool isInsertedInstruction(Instruction *I) const {
return InsertedInstructions.count(I);
}
/// getOrInsertCanonicalInductionVariable - This method returns the
/// canonical induction variable of the specified type for the specified
/// loop (inserting one if there is none). A canonical induction variable
/// starts at zero and steps by one on each iteration.
Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty){
assert((Ty->isInteger() || Ty->isFloatingPoint()) &&
"Can only insert integer or floating point induction variables!");
SCEVHandle H = SCEVAddRecExpr::get(SCEVUnknown::getIntegerSCEV(0, Ty),
SCEVUnknown::getIntegerSCEV(1, Ty), L);
return expand(H);
}
/// addInsertedValue - Remember the specified instruction as being the
/// canonical form for the specified SCEV.
void addInsertedValue(Instruction *I, SCEV *S) {
InsertedExpressions[S] = (Value*)I;
InsertedInstructions.insert(I);
}
/// expandCodeFor - Insert code to directly compute the specified SCEV
/// expression into the program. The inserted code is inserted into the
/// specified block.
///
/// If a particular value sign is required, a type may be specified for the
/// result.
Value *expandCodeFor(SCEVHandle SH, Instruction *IP, const Type *Ty = 0) {
// Expand the code for this SCEV.
this->InsertPt = IP;
return expandInTy(SH, Ty);
}
/// InsertCastOfTo - Insert a cast of V to the specified type, doing what
/// we can to share the casts.
static Value *InsertCastOfTo(Value *V, const Type *Ty);
protected:
Value *expand(SCEV *S) {
// Check to see if we already expanded this.
std::map<SCEVHandle, Value*>::iterator I = InsertedExpressions.find(S);
if (I != InsertedExpressions.end())
return I->second;
Value *V = visit(S);
InsertedExpressions[S] = V;
return V;
}
Value *expandInTy(SCEV *S, const Type *Ty) {
Value *V = expand(S);
if (Ty && V->getType() != Ty)
return InsertCastOfTo(V, Ty);
return V;
}
Value *visitConstant(SCEVConstant *S) {
return S->getValue();
}
Value *visitTruncateExpr(SCEVTruncateExpr *S) {
Value *V = expand(S->getOperand());
return new CastInst(V, S->getType(), "tmp.", InsertPt);
}
Value *visitZeroExtendExpr(SCEVZeroExtendExpr *S) {
Value *V = expandInTy(S->getOperand(),S->getType()->getUnsignedVersion());
return new CastInst(V, S->getType(), "tmp.", InsertPt);
}
Value *visitAddExpr(SCEVAddExpr *S) {
const Type *Ty = S->getType();
Value *V = expandInTy(S->getOperand(S->getNumOperands()-1), Ty);
// Emit a bunch of add instructions
for (int i = S->getNumOperands()-2; i >= 0; --i)
V = BinaryOperator::createAdd(V, expandInTy(S->getOperand(i), Ty),
"tmp.", InsertPt);
return V;
}
Value *visitMulExpr(SCEVMulExpr *S);
Value *visitUDivExpr(SCEVUDivExpr *S) {
const Type *Ty = S->getType();
Value *LHS = expandInTy(S->getLHS(), Ty);
Value *RHS = expandInTy(S->getRHS(), Ty);
return BinaryOperator::createDiv(LHS, RHS, "tmp.", InsertPt);
}
Value *visitAddRecExpr(SCEVAddRecExpr *S);
Value *visitUnknown(SCEVUnknown *S) {
return S->getValue();
}
};
}
#endif