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[LoopUnswitch] Require DominatorTree info. 

Summary:
We should either require the DT info to be available, or check if it's
available in every place we use DT (and we already miss such check in
one place, which causes failures in some cases). As other loop passes
preserve DT and it's usually available, it makes sense to just require
it here.

There is no regression test, because the bug only shows up if pass
manager decides to clean DT info right before LoopUnswitch. If
loop-unswitch is run separately, DT is available, so bug isn't exposed.

Reviewers: chandlerc, hfinkel

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D13036

llvm-svn: 248230
This commit is contained in:
Michael Zolotukhin 2015-09-22 00:22:47 +00:00
parent 7167585c94
commit 9f3aea6e1f
1 changed files with 7 additions and 11 deletions
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12
llvm/lib/Transforms/Scalar/LoopUnswitch.cpp
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@ -193,6 +193,7 @@ namespace {
AU.addPreserved<LoopInfoWrapperPass>();
AU.addRequiredID(LCSSAID);
AU.addPreservedID(LCSSAID);
AU.addRequired<DominatorTreeWrapperPass>();
AU.addPreserved<DominatorTreeWrapperPass>();
AU.addPreserved<ScalarEvolutionWrapperPass>();
AU.addRequired<TargetTransformInfoWrapperPass>();
@ -412,23 +413,19 @@ bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) {
*L->getHeader()->getParent());
LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
LPM = &LPM_Ref;
DominatorTreeWrapperPass *DTWP =
getAnalysisIfAvailable<DominatorTreeWrapperPass>();
DT = DTWP ? &DTWP->getDomTree() : nullptr;
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
currentLoop = L;
Function *F = currentLoop->getHeader()->getParent();
bool Changed = false;
do {
assert(!DT || currentLoop->isLCSSAForm(*DT));
assert(currentLoop->isLCSSAForm(*DT));
redoLoop = false;
Changed |= processCurrentLoop();
} while(redoLoop);
if (Changed) {
// FIXME: Reconstruct dom info, because it is not preserved properly.
if (DT)
if (Changed)
DT->recalculate(*F);
}
return Changed;
}
@ -1196,7 +1193,6 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
// domtree here -- instead we force it to do a full recomputation
// after the pass is complete -- but we do need to inform it of
// new blocks.
if (DT)
DT->addNewBlock(Abort, NewSISucc);
}