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019104459d
llvm-svn: 22565
181 lines
6.7 KiB
C++
181 lines
6.7 KiB
C++
//===---- llvm/Analysis/ScalarEvolutionExpander.h - SCEV Exprs --*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the classes used to generate code from scalar expressions.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
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#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
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#include "llvm/BasicBlock.h"
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#include "llvm/Constants.h"
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#include "llvm/Instructions.h"
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#include "llvm/Type.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Analysis/ScalarEvolutionExpressions.h"
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#include "llvm/Support/CFG.h"
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namespace llvm {
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/// SCEVExpander - This class uses information about analyze scalars to
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/// rewrite expressions in canonical form.
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///
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/// Clients should create an instance of this class when rewriting is needed,
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/// and destroying it when finished to allow the release of the associated
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/// memory.
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struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
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ScalarEvolution &SE;
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LoopInfo &LI;
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std::map<SCEVHandle, Value*> InsertedExpressions;
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std::set<Instruction*> InsertedInstructions;
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Instruction *InsertPt;
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friend struct SCEVVisitor<SCEVExpander, Value*>;
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public:
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SCEVExpander(ScalarEvolution &se, LoopInfo &li) : SE(se), LI(li) {}
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/// clear - Erase the contents of the InsertedExpressions map so that users
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/// trying to expand the same expression into multiple BasicBlocks or
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/// different places within the same BasicBlock can do so.
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void clear() { InsertedExpressions.clear(); }
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/// isInsertedInstruction - Return true if the specified instruction was
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/// inserted by the code rewriter. If so, the client should not modify the
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/// instruction.
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bool isInsertedInstruction(Instruction *I) const {
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return InsertedInstructions.count(I);
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}
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/// getOrInsertCanonicalInductionVariable - This method returns the
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/// canonical induction variable of the specified type for the specified
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/// loop (inserting one if there is none). A canonical induction variable
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/// starts at zero and steps by one on each iteration.
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Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty){
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assert((Ty->isInteger() || Ty->isFloatingPoint()) &&
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"Can only insert integer or floating point induction variables!");
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SCEVHandle H = SCEVAddRecExpr::get(SCEVUnknown::getIntegerSCEV(0, Ty),
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SCEVUnknown::getIntegerSCEV(1, Ty), L);
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return expand(H);
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}
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/// addInsertedValue - Remember the specified instruction as being the
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/// canonical form for the specified SCEV.
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void addInsertedValue(Instruction *I, SCEV *S) {
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InsertedExpressions[S] = (Value*)I;
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InsertedInstructions.insert(I);
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}
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/// expandCodeFor - Insert code to directly compute the specified SCEV
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/// expression into the program. The inserted code is inserted into the
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/// specified block.
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///
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/// If a particular value sign is required, a type may be specified for the
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/// result.
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Value *expandCodeFor(SCEVHandle SH, Instruction *IP, const Type *Ty = 0) {
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// Expand the code for this SCEV.
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this->InsertPt = IP;
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return expandInTy(SH, Ty);
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}
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protected:
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Value *expand(SCEV *S) {
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// Check to see if we already expanded this.
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std::map<SCEVHandle, Value*>::iterator I = InsertedExpressions.find(S);
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if (I != InsertedExpressions.end())
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return I->second;
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Value *V = visit(S);
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InsertedExpressions[S] = V;
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return V;
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}
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Value *expandInTy(SCEV *S, const Type *Ty) {
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Value *V = expand(S);
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if (Ty && V->getType() != Ty) {
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// FIXME: keep track of the cast instruction.
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if (Constant *C = dyn_cast<Constant>(V))
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return ConstantExpr::getCast(C, Ty);
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else if (Instruction *I = dyn_cast<Instruction>(V)) {
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// Check to see if there is already a cast. If there is, use it.
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for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
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UI != E; ++UI) {
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if ((*UI)->getType() == Ty)
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if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) {
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BasicBlock::iterator It = I; ++It;
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if (isa<InvokeInst>(I))
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It = cast<InvokeInst>(I)->getNormalDest()->begin();
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while (isa<PHINode>(It)) ++It;
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if (It != BasicBlock::iterator(CI)) {
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// Splice the cast immediately after the operand in question.
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BasicBlock::InstListType &InstList =
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It->getParent()->getInstList();
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InstList.splice(It, CI->getParent()->getInstList(), CI);
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}
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return CI;
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}
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}
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BasicBlock::iterator IP = I; ++IP;
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if (InvokeInst *II = dyn_cast<InvokeInst>(I))
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IP = II->getNormalDest()->begin();
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while (isa<PHINode>(IP)) ++IP;
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return new CastInst(V, Ty, V->getName(), IP);
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} else {
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// FIXME: check to see if there is already a cast!
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return new CastInst(V, Ty, V->getName(), InsertPt);
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}
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}
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return V;
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}
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Value *visitConstant(SCEVConstant *S) {
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return S->getValue();
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}
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Value *visitTruncateExpr(SCEVTruncateExpr *S) {
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Value *V = expand(S->getOperand());
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return new CastInst(V, S->getType(), "tmp.", InsertPt);
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}
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Value *visitZeroExtendExpr(SCEVZeroExtendExpr *S) {
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Value *V = expandInTy(S->getOperand(),S->getType()->getUnsignedVersion());
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return new CastInst(V, S->getType(), "tmp.", InsertPt);
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}
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Value *visitAddExpr(SCEVAddExpr *S) {
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const Type *Ty = S->getType();
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Value *V = expandInTy(S->getOperand(S->getNumOperands()-1), Ty);
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// Emit a bunch of add instructions
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for (int i = S->getNumOperands()-2; i >= 0; --i)
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V = BinaryOperator::createAdd(V, expandInTy(S->getOperand(i), Ty),
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"tmp.", InsertPt);
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return V;
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}
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Value *visitMulExpr(SCEVMulExpr *S);
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Value *visitUDivExpr(SCEVUDivExpr *S) {
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const Type *Ty = S->getType();
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Value *LHS = expandInTy(S->getLHS(), Ty);
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Value *RHS = expandInTy(S->getRHS(), Ty);
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return BinaryOperator::createDiv(LHS, RHS, "tmp.", InsertPt);
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}
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Value *visitAddRecExpr(SCEVAddRecExpr *S);
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Value *visitUnknown(SCEVUnknown *S) {
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return S->getValue();
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}
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};
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}
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#endif
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