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Enhance hasConstantValue to ignore undef values in phi nodes. This allows it

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to think that PHI[4, undef] == 4.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17096 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-10-17 21:23:26 +00:00
parent c30bda7540
commit 8143c2bc0d
1 changed files with 3 additions and 2 deletions
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5
lib/Transforms/Utils/Local.cpp
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@ -353,7 +353,8 @@ Value *llvm::hasConstantValue(PHINode *PN) {
//
Value *InVal = 0;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) != PN) // Not the PHI node itself...
if (PN->getIncomingValue(i) != PN && // Not the PHI node itself...
!isa<UndefValue>(PN->getIncomingValue(i)))
if (InVal && PN->getIncomingValue(i) != InVal)
return 0; // Not the same, bail out.
else
@ -363,7 +364,7 @@ Value *llvm::hasConstantValue(PHINode *PN) {
// that only has entries for itself. In this case, there is no entry into the
// loop, so kill the PHI.
//
if (InVal == 0) InVal = Constant::getNullValue(PN->getType());
if (InVal == 0) InVal = UndefValue::get(PN->getType());
// All of the incoming values are the same, return the value now.
return InVal;