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Preserve dominance frontier while trivially unswitching loop.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52438 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Devang Patel
2008-06-18 02:16:38 +00:00
parent 6d0cc55ef3
commit 64cd658223
2 changed files with 39 additions and 0 deletions
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17
lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -610,6 +610,23 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
DT->changeImmediateDominator(NewExit, OrigPH);
DT->changeImmediateDominator(NewPH, OrigPH);
}
if (DF) {
// NewExit is now part of NewPH and Loop Header's dominance
// frontier.
DominanceFrontier::iterator DFI = DF->find(NewPH);
if (DFI != DF->end())
DF->addToFrontier(DFI, NewExit);
DFI = DF->find(L->getHeader());
DF->addToFrontier(DFI, NewExit);
// ExitBlock does not have successors then NewExit is part of
// its dominance frontier.
if (succ_begin(ExitBlock) == succ_end(ExitBlock)) {
DFI = DF->find(ExitBlock);
DF->addToFrontier(DFI, NewExit);
}
}
LPM->deleteSimpleAnalysisValue(OrigPH->getTerminator(), L);
OrigPH->getTerminator()->eraseFromParent();