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Implement a small optimization to handling of GEP's that are equivalent to casts.

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This results in substantially reduced collapsing for some testcases


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10002 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-11-14 17:09:46 +00:00
parent db9546e324
commit 179bc7dcb1
1 changed files with 18 additions and 0 deletions
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18
lib/Analysis/DataStructure/Local.cpp
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@ -308,6 +308,24 @@ void GraphBuilder::visitGetElementPtrInst(User &GEP) {
DSNodeHandle Value = getValueDest(*GEP.getOperand(0));
if (Value.getNode() == 0) return;
// As a special case, if all of the index operands of GEP are constant zeros,
// handle this just like we handle casts (ie, don't do much).
bool AllZeros = true;
for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i)
if (GEP.getOperand(i) !=
Constant::getNullValue(GEP.getOperand(i)->getType())) {
AllZeros = false;
break;
}
// If all of the indices are zero, the result points to the operand without
// applying the type.
if (AllZeros) {
setDestTo(GEP, Value);
return;
}
const PointerType *PTy = cast<PointerType>(GEP.getOperand(0)->getType());
const Type *CurTy = PTy->getElementType();