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Omit extracting a loop if one of the exits is a landing pad. 

The landing pad must accompany the invoke when it's extracted. However, if it
does, then the loop isn't properly extracted. I.e., the resulting extraction has
a loop in it. The extracted function is then extracted, etc. resulting in an
infinite loop.

llvm-svn: 140193
This commit is contained in:
Bill Wendling 2011-09-20 22:23:09 +00:00
parent 7c2b28a16f
commit 0058520770
1 changed files with 11 additions and 5 deletions
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16
llvm/lib/Transforms/IPO/LoopExtractor.cpp
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@ -101,19 +101,25 @@ bool LoopExtractor::runOnLoop(Loop *L, LPPassManager &LPM) {
L->getHeader()->getParent()->getEntryBlock().getTerminator();
if (!isa<BranchInst>(EntryTI) ||
!cast<BranchInst>(EntryTI)->isUnconditional() ||
EntryTI->getSuccessor(0) != L->getHeader())
EntryTI->getSuccessor(0) != L->getHeader()) {
ShouldExtractLoop = true;
else {
} else {
// Check to see if any exits from the loop are more than just return
// blocks.
// blocks. We also must omit landing pads. Landing pads must accompany the
// invoke instruction. But this would result in a loop in the extracted
// function. An infinite cycle occurs when it tries to extract that loop as
// well.
SmallVector<BasicBlock*, 8> ExitBlocks;
L->getExitBlocks(ExitBlocks);
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
if (!isa<ReturnInst>(ExitBlocks[i]->getTerminator())) {
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
if (!isa<ReturnInst>(ExitBlocks[i]->getTerminator()))
ShouldExtractLoop = true;
if (ExitBlocks[i]->isLandingPad()) {
ShouldExtractLoop = false;
break;
}
}
}
if (ShouldExtractLoop) {
if (NumLoops == 0) return Changed;
--NumLoops;