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LoopVectorizer: Fix an endless loop in the code that looks for reductions.

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The bug was in the code that detects PHIs in if-then-else block sequence.

PR14701.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171008 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem
2012-12-24 01:22:06 +00:00
parent a048c237e6
commit 470ea9b72f
2 changed files with 52 additions and 7 deletions
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15
lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -1737,10 +1737,9 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
Instruction *ExitInstruction = 0;
// Iter is our iterator. We start with the PHI node and scan for all of the
// users of this instruction. All users must be instructions which can be
// users of this instruction. All users must be instructions that can be
// used as reduction variables (such as ADD). We may have a single
// out-of-block user. They cycle must end with the original PHI.
// Also, we can't have multiple block-local users.
// out-of-block user. The cycle must end with the original PHI.
Instruction *Iter = Phi;
while (true) {
// If the instruction has no users then this is a broken
@ -1752,9 +1751,9 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
if (!isReductionInstr(Iter, Kind))
return false;
// Did we find a user inside this block ?
// Did we find a user inside this loop already ?
bool FoundInBlockUser = false;
// Did we reach the initial PHI node ?
// Did we reach the initial PHI node already ?
bool FoundStartPHI = false;
// For each of the *users* of iter.
@ -1779,8 +1778,10 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
// We allow in-loop PHINodes which are not the original reduction PHI
// node. If this PHI is the only user of Iter (happens in IF w/ no ELSE
// structure) then don't skip this PHI.
if (isa<PHINode>(U) && U->getParent() != TheLoop->getHeader() &&
TheLoop->contains(U) && Iter->getNumUses() > 1)
if (isa<PHINode>(Iter) && isa<PHINode>(U) &&
U->getParent() != TheLoop->getHeader() &&
TheLoop->contains(U) &&
Iter->getNumUses() > 1)
continue;
// We can't have multiple inside users.