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LoopVectorize: Handle single edge PHIs

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We might encouter single edge PHIs - handle them with an identity select.

Fixes PR15990.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182199 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Arnold Schwaighofer
2013-05-18 18:38:34 +00:00
parent edc399aceb
commit 688b5103eb
2 changed files with 26 additions and 4 deletions
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8
lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -2105,7 +2105,6 @@ InnerLoopVectorizer::vectorizeBlockInLoop(LoopVectorizationLegality *Legal,
// optimizations will clean it up.
unsigned NumIncoming = P->getNumIncomingValues();
assert(NumIncoming > 1 && "Invalid PHI");
// Generate a sequence of selects of the form:
// SELECT(Mask3, In3,
@ -2117,10 +2116,11 @@ InnerLoopVectorizer::vectorizeBlockInLoop(LoopVectorizationLegality *Legal,
VectorParts &In0 = getVectorValue(P->getIncomingValue(In));
for (unsigned part = 0; part < UF; ++part) {
// We don't need to 'select' the first PHI operand because it is
// the default value if all of the other masks don't match.
// We might have single edge PHIs (blocks) - use an identity
// 'select' for the first PHI operand.
if (In == 0)
Entry[part] = In0[part];
Entry[part] = Builder.CreateSelect(Cond[part], In0[part],
In0[part]);
else
// Select between the current value and the previous incoming edge
// based on the incoming mask.