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Fix ScalarEvolutionExpander when creating a PHI in a block with duplicate predecessors

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It seems that when I fixed this, almost exactly a year ago, I did not quite do
it correctly. When we have duplicate block predecessors, we can indeed not have
different incoming values for the same block, but we *must* have duplicate
entries. So, instead of skipping the duplicates, we explicitly add the
duplicate incoming values.

Fixes PR20442.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214423 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel
2014-07-31 19:13:38 +00:00
parent 94f7c7aeaa
commit 50c05c91f9
2 changed files with 84 additions and 1 deletions
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6
lib/Analysis/ScalarEvolutionExpander.cpp
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@ -1443,8 +1443,12 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
Constant *One = ConstantInt::get(Ty, 1);
for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
BasicBlock *HP = *HPI;
if (!PredSeen.insert(HP))
if (!PredSeen.insert(HP)) {
// There must be an incoming value for each predecessor, even the
// duplicates!
CanonicalIV->addIncoming(CanonicalIV->getIncomingValueForBlock(HP), HP);
continue;
}
if (L->contains(HP)) {
// Insert a unit add instruction right before the terminator