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Fix PR2496, a really nasty bug which involved sinking volatile loads

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into phis.  This is actually the same bug as PR2262 /
2008-04-29-VolatileLoadDontMerge.ll, but I missed checking the first 
predecessor for multiple successors.  Testcase here:
InstCombine/2008-07-08-VolatileLoadMerge.ll



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53240 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-07-08 17:18:32 +00:00
parent 895860e27b
commit 710429645a
1 changed files with 11 additions and 3 deletions
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14
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -9354,6 +9354,14 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
if (LI->getParent() != PN.getIncomingBlock(0) ||
!isSafeToSinkLoad(LI))
return 0;
// If the PHI is of volatile loads and the load block has multiple
// successors, sinking it would remove a load of the volatile value from
// the path through the other successor.
if (isVolatile &&
LI->getParent()->getTerminator()->getNumSuccessors() != 1)
return 0;
} else if (isa<GetElementPtrInst>(FirstInst)) {
if (FirstInst->getNumOperands() == 2)
return FoldPHIArgBinOpIntoPHI(PN);
@ -9380,9 +9388,9 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
!isSafeToSinkLoad(LI))
return 0;
// If the PHI is volatile and its block has multiple successors, sinking
// it would remove a load of the volatile value from the path through the
// other successor.
// If the PHI is of volatile loads and the load block has multiple
// successors, sinking it would remove a load of the volatile value from
// the path through the other successor.
if (isVolatile &&
LI->getParent()->getTerminator()->getNumSuccessors() != 1)
return 0;