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reenable factoring of GEP expressions, being more precise about the 

case that it bad to do.

llvm-svn: 31563
This commit is contained in:
Chris Lattner 2006-11-08 19:42:28 +00:00
parent cd62f11227
commit 4f218d56f5
1 changed files with 10 additions and 5 deletions
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15
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -6788,12 +6788,17 @@ Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
if (I->getOperand(1) != RHSVal) RHSVal = 0;
}
// Otherwise, this is safe and profitable to transform. Create up to two phi
// nodes.
PHINode *NewLHS = 0, *NewRHS = 0;
// Otherwise, this is safe to transform, determine if it is profitable.
// If this is a GEP, and if the index (not the pointer) needs a PHI, bail out.
// Indexes are often folded into load/store instructions, so we don't want to
// hide them behind a phi.
if (isa<GetElementPtrInst>(FirstInst) && RHSVal == 0)
return 0;
Value *InLHS = FirstInst->getOperand(0);
Value *InRHS = FirstInst->getOperand(1);
PHINode *NewLHS = 0, *NewRHS = 0;
if (LHSVal == 0) {
NewLHS = new PHINode(LHSType, FirstInst->getOperand(0)->getName()+".pn");
NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
@ -6875,7 +6880,7 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
!isSafeToSinkLoad(LI))
return 0;
} else if (isa<GetElementPtrInst>(FirstInst)) {
if (0 && FirstInst->getNumOperands() == 2)
if (FirstInst->getNumOperands() == 2)
return FoldPHIArgBinOpIntoPHI(PN);
// Can't handle general GEPs yet.
return 0;