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//===---- 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 destroy 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() && "Can only insert integer 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(Instruction::CastOps opcode, Value *V,
const Type *Ty);
/// InsertBinop - Insert the specified binary operator, doing a small amount
/// of work to avoid inserting an obviously redundant operation.
static Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS,
Value *RHS, Instruction *&InsertPt);
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) {
if (isa<PointerType>(Ty) && V->getType()->isInteger())
return InsertCastOfTo(Instruction::IntToPtr, V, Ty);
else if (Ty->isInteger() && isa<PointerType>(V->getType()))
return InsertCastOfTo(Instruction::PtrToInt, V, Ty);
else if (Ty->getPrimitiveSizeInBits() ==
V->getType()->getPrimitiveSizeInBits())
return InsertCastOfTo(Instruction::BitCast, V, Ty);
else if (Ty->getPrimitiveSizeInBits() >
V->getType()->getPrimitiveSizeInBits())
return InsertCastOfTo(Instruction::ZExt, V, Ty);
else
return InsertCastOfTo(Instruction::Trunc, V, Ty);
}
return V;
}
Value *visitConstant(SCEVConstant *S) {
return S->getValue();
}
Value *visitTruncateExpr(SCEVTruncateExpr *S) {
Value *V = expand(S->getOperand());
return CastInst::createTruncOrBitCast(V, S->getType(), "tmp.", InsertPt);
}
Value *visitZeroExtendExpr(SCEVZeroExtendExpr *S) {
Value *V = expandInTy(S->getOperand(), S->getType());
return CastInst::createZExtOrBitCast(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 = InsertBinop(Instruction::Add, V, expandInTy(S->getOperand(i), Ty),
InsertPt);
return V;
}
Value *visitMulExpr(SCEVMulExpr *S);
Value *visitSDivExpr(SCEVSDivExpr *S) {
const Type *Ty = S->getType();
Value *LHS = expandInTy(S->getLHS(), Ty);
Value *RHS = expandInTy(S->getRHS(), Ty);
return InsertBinop(Instruction::SDiv, LHS, RHS, InsertPt);
}
Value *visitAddRecExpr(SCEVAddRecExpr *S);
Value *visitUnknown(SCEVUnknown *S) {
return S->getValue();
}
};
}
#endif
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