| //===- ScalarEvolutionExpander.cpp - Scalar Evolution Analysis --*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains the implementation of the scalar evolution expander, |
| // which is used to generate the code corresponding to a given scalar evolution |
| // expression. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Analysis/ScalarEvolutionExpander.h" |
| #include "llvm/Analysis/LoopInfo.h" |
| #include "llvm/Target/TargetData.h" |
| using namespace llvm; |
| |
| /// InsertCastOfTo - Insert a cast of V to the specified type, doing what |
| /// we can to share the casts. |
| Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V, |
| const Type *Ty) { |
| // Short-circuit unnecessary bitcasts. |
| if (opcode == Instruction::BitCast && V->getType() == Ty) |
| return V; |
| |
| // Short-circuit unnecessary inttoptr<->ptrtoint casts. |
| if ((opcode == Instruction::PtrToInt || opcode == Instruction::IntToPtr) && |
| SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) { |
| if (CastInst *CI = dyn_cast<CastInst>(V)) |
| if ((CI->getOpcode() == Instruction::PtrToInt || |
| CI->getOpcode() == Instruction::IntToPtr) && |
| SE.getTypeSizeInBits(CI->getType()) == |
| SE.getTypeSizeInBits(CI->getOperand(0)->getType())) |
| return CI->getOperand(0); |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) |
| if ((CE->getOpcode() == Instruction::PtrToInt || |
| CE->getOpcode() == Instruction::IntToPtr) && |
| SE.getTypeSizeInBits(CE->getType()) == |
| SE.getTypeSizeInBits(CE->getOperand(0)->getType())) |
| return CE->getOperand(0); |
| } |
| |
| // FIXME: keep track of the cast instruction. |
| if (Constant *C = dyn_cast<Constant>(V)) |
| return ConstantExpr::getCast(opcode, C, Ty); |
| |
| if (Argument *A = dyn_cast<Argument>(V)) { |
| // Check to see if there is already a cast! |
| for (Value::use_iterator UI = A->use_begin(), E = A->use_end(); |
| UI != E; ++UI) { |
| if ((*UI)->getType() == Ty) |
| if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) |
| if (CI->getOpcode() == opcode) { |
| // If the cast isn't the first instruction of the function, move it. |
| if (BasicBlock::iterator(CI) != |
| A->getParent()->getEntryBlock().begin()) { |
| // If the CastInst is the insert point, change the insert point. |
| if (CI == InsertPt) ++InsertPt; |
| // Splice the cast at the beginning of the entry block. |
| CI->moveBefore(A->getParent()->getEntryBlock().begin()); |
| } |
| return CI; |
| } |
| } |
| Instruction *I = CastInst::Create(opcode, V, Ty, V->getName(), |
| A->getParent()->getEntryBlock().begin()); |
| InsertedValues.insert(I); |
| return I; |
| } |
| |
| Instruction *I = cast<Instruction>(V); |
| |
| // Check to see if there is already a cast. If there is, use it. |
| for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); |
| UI != E; ++UI) { |
| if ((*UI)->getType() == Ty) |
| if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) |
| if (CI->getOpcode() == opcode) { |
| BasicBlock::iterator It = I; ++It; |
| if (isa<InvokeInst>(I)) |
| It = cast<InvokeInst>(I)->getNormalDest()->begin(); |
| while (isa<PHINode>(It)) ++It; |
| if (It != BasicBlock::iterator(CI)) { |
| // If the CastInst is the insert point, change the insert point. |
| if (CI == InsertPt) ++InsertPt; |
| // Splice the cast immediately after the operand in question. |
| CI->moveBefore(It); |
| } |
| return CI; |
| } |
| } |
| BasicBlock::iterator IP = I; ++IP; |
| if (InvokeInst *II = dyn_cast<InvokeInst>(I)) |
| IP = II->getNormalDest()->begin(); |
| while (isa<PHINode>(IP)) ++IP; |
| Instruction *CI = CastInst::Create(opcode, V, Ty, V->getName(), IP); |
| InsertedValues.insert(CI); |
| return CI; |
| } |
| |
| /// InsertNoopCastOfTo - Insert a cast of V to the specified type, |
| /// which must be possible with a noop cast. |
| Value *SCEVExpander::InsertNoopCastOfTo(Value *V, const Type *Ty) { |
| Instruction::CastOps Op = CastInst::getCastOpcode(V, false, Ty, false); |
| assert((Op == Instruction::BitCast || |
| Op == Instruction::PtrToInt || |
| Op == Instruction::IntToPtr) && |
| "InsertNoopCastOfTo cannot perform non-noop casts!"); |
| assert(SE.getTypeSizeInBits(V->getType()) == SE.getTypeSizeInBits(Ty) && |
| "InsertNoopCastOfTo cannot change sizes!"); |
| return InsertCastOfTo(Op, V, Ty); |
| } |
| |
| /// InsertBinop - Insert the specified binary operator, doing a small amount |
| /// of work to avoid inserting an obviously redundant operation. |
| Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, |
| Value *RHS, BasicBlock::iterator InsertPt) { |
| // Fold a binop with constant operands. |
| if (Constant *CLHS = dyn_cast<Constant>(LHS)) |
| if (Constant *CRHS = dyn_cast<Constant>(RHS)) |
| return ConstantExpr::get(Opcode, CLHS, CRHS); |
| |
| // Do a quick scan to see if we have this binop nearby. If so, reuse it. |
| unsigned ScanLimit = 6; |
| BasicBlock::iterator BlockBegin = InsertPt->getParent()->begin(); |
| if (InsertPt != BlockBegin) { |
| // Scanning starts from the last instruction before InsertPt. |
| BasicBlock::iterator IP = InsertPt; |
| --IP; |
| for (; ScanLimit; --IP, --ScanLimit) { |
| if (IP->getOpcode() == (unsigned)Opcode && IP->getOperand(0) == LHS && |
| IP->getOperand(1) == RHS) |
| return IP; |
| if (IP == BlockBegin) break; |
| } |
| } |
| |
| // If we haven't found this binop, insert it. |
| Instruction *BO = BinaryOperator::Create(Opcode, LHS, RHS, "tmp", InsertPt); |
| InsertedValues.insert(BO); |
| return BO; |
| } |
| |
| /// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP |
| /// instead of using ptrtoint+arithmetic+inttoptr. |
| Value *SCEVExpander::expandAddToGEP(const SCEVAddExpr *S, |
| const PointerType *PTy, |
| const Type *Ty, |
| Value *V) { |
| const Type *ElTy = PTy->getElementType(); |
| SmallVector<Value *, 4> GepIndices; |
| std::vector<SCEVHandle> Ops = S->getOperands(); |
| bool AnyNonZeroIndices = false; |
| Ops.pop_back(); |
| |
| // Decend down the pointer's type and attempt to convert the other |
| // operands into GEP indices, at each level. The first index in a GEP |
| // indexes into the array implied by the pointer operand; the rest of |
| // the indices index into the element or field type selected by the |
| // preceding index. |
| for (;;) { |
| APInt ElSize = APInt(SE.getTypeSizeInBits(Ty), |
| ElTy->isSized() ? SE.TD->getTypeAllocSize(ElTy) : 0); |
| std::vector<SCEVHandle> NewOps; |
| std::vector<SCEVHandle> ScaledOps; |
| for (unsigned i = 0, e = Ops.size(); i != e; ++i) { |
| if (ElSize != 0) { |
| if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) |
| if (!C->getValue()->getValue().srem(ElSize)) { |
| ConstantInt *CI = |
| ConstantInt::get(C->getValue()->getValue().sdiv(ElSize)); |
| SCEVHandle Div = SE.getConstant(CI); |
| ScaledOps.push_back(Div); |
| continue; |
| } |
| if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) |
| if (const SCEVConstant *C = dyn_cast<SCEVConstant>(M->getOperand(0))) |
| if (C->getValue()->getValue() == ElSize) { |
| for (unsigned j = 1, f = M->getNumOperands(); j != f; ++j) |
| ScaledOps.push_back(M->getOperand(j)); |
| continue; |
| } |
| if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Ops[i])) |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U->getValue())) |
| if (BO->getOpcode() == Instruction::Mul) |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1))) |
| if (CI->getValue() == ElSize) { |
| ScaledOps.push_back(SE.getUnknown(BO->getOperand(0))); |
| continue; |
| } |
| if (ElSize == 1) { |
| ScaledOps.push_back(Ops[i]); |
| continue; |
| } |
| } |
| NewOps.push_back(Ops[i]); |
| } |
| Ops = NewOps; |
| AnyNonZeroIndices |= !ScaledOps.empty(); |
| Value *Scaled = ScaledOps.empty() ? |
| Constant::getNullValue(Ty) : |
| expandCodeFor(SE.getAddExpr(ScaledOps), Ty); |
| GepIndices.push_back(Scaled); |
| |
| // Collect struct field index operands. |
| if (!Ops.empty()) |
| while (const StructType *STy = dyn_cast<StructType>(ElTy)) { |
| if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[0])) |
| if (SE.getTypeSizeInBits(C->getType()) <= 64) { |
| const StructLayout &SL = *SE.TD->getStructLayout(STy); |
| uint64_t FullOffset = C->getValue()->getZExtValue(); |
| if (FullOffset < SL.getSizeInBytes()) { |
| unsigned ElIdx = SL.getElementContainingOffset(FullOffset); |
| GepIndices.push_back(ConstantInt::get(Type::Int32Ty, ElIdx)); |
| ElTy = STy->getTypeAtIndex(ElIdx); |
| Ops[0] = |
| SE.getConstant(ConstantInt::get(Ty, |
| FullOffset - |
| SL.getElementOffset(ElIdx))); |
| AnyNonZeroIndices = true; |
| continue; |
| } |
| } |
| break; |
| } |
| |
| if (const ArrayType *ATy = dyn_cast<ArrayType>(ElTy)) { |
| ElTy = ATy->getElementType(); |
| continue; |
| } |
| break; |
| } |
| |
| // If none of the operands were convertable to proper GEP indices, cast |
| // the base to i8* and do an ugly getelementptr with that. It's still |
| // better than ptrtoint+arithmetic+inttoptr at least. |
| if (!AnyNonZeroIndices) { |
| V = InsertNoopCastOfTo(V, |
| Type::Int8Ty->getPointerTo(PTy->getAddressSpace())); |
| Value *Idx = expand(SE.getAddExpr(Ops)); |
| Idx = InsertNoopCastOfTo(Idx, Ty); |
| |
| // Fold a GEP with constant operands. |
| if (Constant *CLHS = dyn_cast<Constant>(V)) |
| if (Constant *CRHS = dyn_cast<Constant>(Idx)) |
| return ConstantExpr::get(Instruction::GetElementPtr, CLHS, CRHS); |
| |
| // Do a quick scan to see if we have this GEP nearby. If so, reuse it. |
| unsigned ScanLimit = 6; |
| BasicBlock::iterator BlockBegin = InsertPt->getParent()->begin(); |
| if (InsertPt != BlockBegin) { |
| // Scanning starts from the last instruction before InsertPt. |
| BasicBlock::iterator IP = InsertPt; |
| --IP; |
| for (; ScanLimit; --IP, --ScanLimit) { |
| if (IP->getOpcode() == Instruction::GetElementPtr && |
| IP->getOperand(0) == V && IP->getOperand(1) == Idx) |
| return IP; |
| if (IP == BlockBegin) break; |
| } |
| } |
| |
| Value *GEP = GetElementPtrInst::Create(V, Idx, "scevgep", InsertPt); |
| InsertedValues.insert(GEP); |
| return GEP; |
| } |
| |
| // Insert a pretty getelementptr. |
| Value *GEP = GetElementPtrInst::Create(V, |
| GepIndices.begin(), |
| GepIndices.end(), |
| "scevgep", InsertPt); |
| Ops.push_back(SE.getUnknown(GEP)); |
| InsertedValues.insert(GEP); |
| return expand(SE.getAddExpr(Ops)); |
| } |
| |
| Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) { |
| const Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| Value *V = expand(S->getOperand(S->getNumOperands()-1)); |
| |
| // Turn things like ptrtoint+arithmetic+inttoptr into GEP. This helps |
| // BasicAliasAnalysis analyze the result. However, it suffers from the |
| // underlying bug described in PR2831. Addition in LLVM currently always |
| // has two's complement wrapping guaranteed. However, the semantics for |
| // getelementptr overflow are ambiguous. In the common case though, this |
| // expansion gets used when a GEP in the original code has been converted |
| // into integer arithmetic, in which case the resulting code will be no |
| // more undefined than it was originally. |
| if (SE.TD) |
| if (const PointerType *PTy = dyn_cast<PointerType>(V->getType())) |
| return expandAddToGEP(S, PTy, Ty, V); |
| |
| V = InsertNoopCastOfTo(V, Ty); |
| |
| // Emit a bunch of add instructions |
| for (int i = S->getNumOperands()-2; i >= 0; --i) { |
| Value *W = expand(S->getOperand(i)); |
| W = InsertNoopCastOfTo(W, Ty); |
| V = InsertBinop(Instruction::Add, V, W, InsertPt); |
| } |
| return V; |
| } |
| |
| Value *SCEVExpander::visitMulExpr(const SCEVMulExpr *S) { |
| const Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| int FirstOp = 0; // Set if we should emit a subtract. |
| if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getOperand(0))) |
| if (SC->getValue()->isAllOnesValue()) |
| FirstOp = 1; |
| |
| int i = S->getNumOperands()-2; |
| Value *V = expand(S->getOperand(i+1)); |
| V = InsertNoopCastOfTo(V, Ty); |
| |
| // Emit a bunch of multiply instructions |
| for (; i >= FirstOp; --i) { |
| Value *W = expand(S->getOperand(i)); |
| W = InsertNoopCastOfTo(W, Ty); |
| V = InsertBinop(Instruction::Mul, V, W, InsertPt); |
| } |
| |
| // -1 * ... ---> 0 - ... |
| if (FirstOp == 1) |
| V = InsertBinop(Instruction::Sub, Constant::getNullValue(Ty), V, InsertPt); |
| return V; |
| } |
| |
| Value *SCEVExpander::visitUDivExpr(const SCEVUDivExpr *S) { |
| const Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| |
| Value *LHS = expand(S->getLHS()); |
| LHS = InsertNoopCastOfTo(LHS, Ty); |
| if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(S->getRHS())) { |
| const APInt &RHS = SC->getValue()->getValue(); |
| if (RHS.isPowerOf2()) |
| return InsertBinop(Instruction::LShr, LHS, |
| ConstantInt::get(Ty, RHS.logBase2()), |
| InsertPt); |
| } |
| |
| Value *RHS = expand(S->getRHS()); |
| RHS = InsertNoopCastOfTo(RHS, Ty); |
| return InsertBinop(Instruction::UDiv, LHS, RHS, InsertPt); |
| } |
| |
| Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) { |
| const Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| const Loop *L = S->getLoop(); |
| |
| // {X,+,F} --> X + {0,+,F} |
| if (!S->getStart()->isZero()) { |
| std::vector<SCEVHandle> NewOps(S->getOperands()); |
| NewOps[0] = SE.getIntegerSCEV(0, Ty); |
| Value *Rest = expand(SE.getAddRecExpr(NewOps, L)); |
| return expand(SE.getAddExpr(S->getStart(), SE.getUnknown(Rest))); |
| } |
| |
| // {0,+,1} --> Insert a canonical induction variable into the loop! |
| if (S->isAffine() && |
| S->getOperand(1) == SE.getIntegerSCEV(1, Ty)) { |
| // Create and insert the PHI node for the induction variable in the |
| // specified loop. |
| BasicBlock *Header = L->getHeader(); |
| PHINode *PN = PHINode::Create(Ty, "indvar", Header->begin()); |
| InsertedValues.insert(PN); |
| PN->addIncoming(Constant::getNullValue(Ty), L->getLoopPreheader()); |
| |
| pred_iterator HPI = pred_begin(Header); |
| assert(HPI != pred_end(Header) && "Loop with zero preds???"); |
| if (!L->contains(*HPI)) ++HPI; |
| assert(HPI != pred_end(Header) && L->contains(*HPI) && |
| "No backedge in loop?"); |
| |
| // Insert a unit add instruction right before the terminator corresponding |
| // to the back-edge. |
| Constant *One = ConstantInt::get(Ty, 1); |
| Instruction *Add = BinaryOperator::CreateAdd(PN, One, "indvar.next", |
| (*HPI)->getTerminator()); |
| InsertedValues.insert(Add); |
| |
| pred_iterator PI = pred_begin(Header); |
| if (*PI == L->getLoopPreheader()) |
| ++PI; |
| PN->addIncoming(Add, *PI); |
| return PN; |
| } |
| |
| // Get the canonical induction variable I for this loop. |
| Value *I = getOrInsertCanonicalInductionVariable(L, Ty); |
| |
| // If this is a simple linear addrec, emit it now as a special case. |
| if (S->isAffine()) { // {0,+,F} --> i*F |
| Value *F = expand(S->getOperand(1)); |
| F = InsertNoopCastOfTo(F, Ty); |
| |
| // IF the step is by one, just return the inserted IV. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(F)) |
| if (CI->getValue() == 1) |
| return I; |
| |
| // If the insert point is directly inside of the loop, emit the multiply at |
| // the insert point. Otherwise, L is a loop that is a parent of the insert |
| // point loop. If we can, move the multiply to the outer most loop that it |
| // is safe to be in. |
| BasicBlock::iterator MulInsertPt = getInsertionPoint(); |
| Loop *InsertPtLoop = SE.LI->getLoopFor(MulInsertPt->getParent()); |
| if (InsertPtLoop != L && InsertPtLoop && |
| L->contains(InsertPtLoop->getHeader())) { |
| do { |
| // If we cannot hoist the multiply out of this loop, don't. |
| if (!InsertPtLoop->isLoopInvariant(F)) break; |
| |
| BasicBlock *InsertPtLoopPH = InsertPtLoop->getLoopPreheader(); |
| |
| // If this loop hasn't got a preheader, we aren't able to hoist the |
| // multiply. |
| if (!InsertPtLoopPH) |
| break; |
| |
| // Otherwise, move the insert point to the preheader. |
| MulInsertPt = InsertPtLoopPH->getTerminator(); |
| InsertPtLoop = InsertPtLoop->getParentLoop(); |
| } while (InsertPtLoop != L); |
| } |
| |
| return InsertBinop(Instruction::Mul, I, F, MulInsertPt); |
| } |
| |
| // If this is a chain of recurrences, turn it into a closed form, using the |
| // folders, then expandCodeFor the closed form. This allows the folders to |
| // simplify the expression without having to build a bunch of special code |
| // into this folder. |
| SCEVHandle IH = SE.getUnknown(I); // Get I as a "symbolic" SCEV. |
| |
| SCEVHandle V = S->evaluateAtIteration(IH, SE); |
| //cerr << "Evaluated: " << *this << "\n to: " << *V << "\n"; |
| |
| return expand(V); |
| } |
| |
| Value *SCEVExpander::visitTruncateExpr(const SCEVTruncateExpr *S) { |
| const Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| Value *V = expand(S->getOperand()); |
| V = InsertNoopCastOfTo(V, SE.getEffectiveSCEVType(V->getType())); |
| Instruction *I = new TruncInst(V, Ty, "tmp.", InsertPt); |
| InsertedValues.insert(I); |
| return I; |
| } |
| |
| Value *SCEVExpander::visitZeroExtendExpr(const SCEVZeroExtendExpr *S) { |
| const Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| Value *V = expand(S->getOperand()); |
| V = InsertNoopCastOfTo(V, SE.getEffectiveSCEVType(V->getType())); |
| Instruction *I = new ZExtInst(V, Ty, "tmp.", InsertPt); |
| InsertedValues.insert(I); |
| return I; |
| } |
| |
| Value *SCEVExpander::visitSignExtendExpr(const SCEVSignExtendExpr *S) { |
| const Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| Value *V = expand(S->getOperand()); |
| V = InsertNoopCastOfTo(V, SE.getEffectiveSCEVType(V->getType())); |
| Instruction *I = new SExtInst(V, Ty, "tmp.", InsertPt); |
| InsertedValues.insert(I); |
| return I; |
| } |
| |
| Value *SCEVExpander::visitSMaxExpr(const SCEVSMaxExpr *S) { |
| const Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| Value *LHS = expand(S->getOperand(0)); |
| LHS = InsertNoopCastOfTo(LHS, Ty); |
| for (unsigned i = 1; i < S->getNumOperands(); ++i) { |
| Value *RHS = expand(S->getOperand(i)); |
| RHS = InsertNoopCastOfTo(RHS, Ty); |
| Instruction *ICmp = |
| new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS, "tmp", InsertPt); |
| InsertedValues.insert(ICmp); |
| Instruction *Sel = SelectInst::Create(ICmp, LHS, RHS, "smax", InsertPt); |
| InsertedValues.insert(Sel); |
| LHS = Sel; |
| } |
| return LHS; |
| } |
| |
| Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) { |
| const Type *Ty = SE.getEffectiveSCEVType(S->getType()); |
| Value *LHS = expand(S->getOperand(0)); |
| LHS = InsertNoopCastOfTo(LHS, Ty); |
| for (unsigned i = 1; i < S->getNumOperands(); ++i) { |
| Value *RHS = expand(S->getOperand(i)); |
| RHS = InsertNoopCastOfTo(RHS, Ty); |
| Instruction *ICmp = |
| new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS, "tmp", InsertPt); |
| InsertedValues.insert(ICmp); |
| Instruction *Sel = SelectInst::Create(ICmp, LHS, RHS, "umax", InsertPt); |
| InsertedValues.insert(Sel); |
| LHS = Sel; |
| } |
| return LHS; |
| } |
| |
| Value *SCEVExpander::expandCodeFor(SCEVHandle SH, const Type *Ty) { |
| // Expand the code for this SCEV. |
| Value *V = expand(SH); |
| if (Ty) { |
| assert(SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(SH->getType()) && |
| "non-trivial casts should be done with the SCEVs directly!"); |
| V = InsertNoopCastOfTo(V, Ty); |
| } |
| return V; |
| } |
| |
| Value *SCEVExpander::expand(const 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; |
| } |