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[LPM] Fix a logic error in LICM spotted by inspection.

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We completely skipped promotion in LICM if the loop has a preheader or
dedicated exits, but not *both*. We hoist if there is a preheader, and
sink if there are dedicated exits, but either hoisting or sinking can
move loop invariant code out of the loop!

I have no idea if this has a practical consequence. If anyone has ideas
for a test case, let me know.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199966 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2014-01-24 02:24:47 +00:00
parent 5950c6fa48
commit 4296ce5662
1 changed files with 1 additions and 1 deletions
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2
lib/Transforms/Scalar/LICM.cpp
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@ -273,7 +273,7 @@ bool LICM::runOnLoop(Loop *L, LPPassManager &LPM) {
// Now that all loop invariants have been removed from the loop, promote any
// memory references to scalars that we can.
if (!DisablePromotion && Preheader && L->hasDedicatedExits()) {
if (!DisablePromotion && (Preheader || L->hasDedicatedExits())) {
SmallVector<BasicBlock *, 8> ExitBlocks;
SmallVector<Instruction *, 8> InsertPts;