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indvars should hoist [sz]ext because licm is not rerun.

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llvm-svn: 140670
This commit is contained in:
Andrew Trick 2011-09-28 01:35:36 +00:00
parent f4f4a75d2b
commit 97b40d3aff
1 changed files with 27 additions and 17 deletions
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44
lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -834,6 +834,9 @@ public:
PHINode *CreateWideIV(SCEVExpander &Rewriter);
protected:
Value *getExtend(Value *NarrowOper, Type *WideType, bool IsSigned,
Instruction *Use);
Instruction *CloneIVUser(NarrowIVDefUse DU);
const SCEVAddRecExpr *GetWideRecurrence(Instruction *NarrowUse);
@ -846,8 +849,27 @@ protected:
};
} // anonymous namespace
static Value *getExtend( Value *NarrowOper, Type *WideType,
bool IsSigned, IRBuilder<> &Builder) {
/// isLoopInvariant - Perform a quick domtree based check for loop invariance
/// assuming that V is used within the loop. LoopInfo::isLoopInvariant() seems
/// gratuitous for this purpose.
static bool isLoopInvariant(Value *V, const Loop *L, const DominatorTree *DT) {
Instruction *Inst = dyn_cast<Instruction>(V);
if (!Inst)
return true;
return DT->properlyDominates(Inst->getParent(), L->getHeader());
}
Value *WidenIV::getExtend(Value *NarrowOper, Type *WideType, bool IsSigned,
Instruction *Use) {
// Set the debug location and conservative insertion point.
IRBuilder<> Builder(Use);
// Hoist the insertion point into loop preheaders as far as possible.
for (const Loop *L = LI->getLoopFor(Use->getParent());
L && L->getLoopPreheader() && isLoopInvariant(NarrowOper, L, DT);
L = L->getParentLoop())
Builder.SetInsertPoint(L->getLoopPreheader()->getTerminator());
return IsSigned ? Builder.CreateSExt(NarrowOper, WideType) :
Builder.CreateZExt(NarrowOper, WideType);
}
@ -872,22 +894,21 @@ Instruction *WidenIV::CloneIVUser(NarrowIVDefUse DU) {
case Instruction::AShr:
DEBUG(dbgs() << "Cloning IVUser: " << *DU.NarrowUse << "\n");
IRBuilder<> Builder(DU.NarrowUse);
// Replace NarrowDef operands with WideDef. Otherwise, we don't know
// anything about the narrow operand yet so must insert a [sz]ext. It is
// probably loop invariant and will be folded or hoisted. If it actually
// comes from a widened IV, it should be removed during a future call to
// WidenIVUse.
Value *LHS = (DU.NarrowUse->getOperand(0) == DU.NarrowDef) ? DU.WideDef :
getExtend(DU.NarrowUse->getOperand(0), WideType, IsSigned, Builder);
getExtend(DU.NarrowUse->getOperand(0), WideType, IsSigned, DU.NarrowUse);
Value *RHS = (DU.NarrowUse->getOperand(1) == DU.NarrowDef) ? DU.WideDef :
getExtend(DU.NarrowUse->getOperand(1), WideType, IsSigned, Builder);
getExtend(DU.NarrowUse->getOperand(1), WideType, IsSigned, DU.NarrowUse);
BinaryOperator *NarrowBO = cast<BinaryOperator>(DU.NarrowUse);
BinaryOperator *WideBO = BinaryOperator::Create(NarrowBO->getOpcode(),
LHS, RHS,
NarrowBO->getName());
IRBuilder<> Builder(DU.NarrowUse);
Builder.Insert(WideBO);
if (const OverflowingBinaryOperator *OBO =
dyn_cast<OverflowingBinaryOperator>(NarrowBO)) {
@ -1391,17 +1412,6 @@ static Type *getBackedgeIVType(Loop *L) {
return Ty;
}
/// isLoopInvariant - Perform a quick domtree based check for loop invariance
/// assuming that V is used within the loop. LoopInfo::isLoopInvariant() seems
/// gratuitous for this purpose.
static bool isLoopInvariant(Value *V, Loop *L, DominatorTree *DT) {
Instruction *Inst = dyn_cast<Instruction>(V);
if (!Inst)
return true;
return DT->properlyDominates(Inst->getParent(), L->getHeader());
}
/// getLoopPhiForCounter - Return the loop header phi IFF IncV adds a loop
/// invariant value to the phi.
static PHINode *getLoopPhiForCounter(Value *IncV, Loop *L, DominatorTree *DT) {