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[LoopUnroll] Unroll loops which have exit blocks to EH pads

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We were overly cautious in our analysis of loops which have invokes
which unwind to EH pads.  The loop unroll transform is safe because it
only clones blocks in the loop body, it does not try to split critical
edges involving EH pads.  Instead, move the necessary safety check to
LoopUnswitch.

N.B. The safety check for loop unswitch is covered by an existing test
which fails without it.

llvm-svn: 268357
This commit is contained in:
David Majnemer
2016-05-03 03:57:40 +00:00
parent 2a4c00f243
commit 3d90bb79c4
4 changed files with 56 additions and 16 deletions
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19
llvm/lib/Analysis/LoopInfo.cpp
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@@ -195,23 +195,10 @@ bool Loop::isSafeToClone() const {
if (isa<IndirectBrInst>(BB->getTerminator()))
return false;
if (const InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
if (II->cannotDuplicate())
return false;
// Return false if any loop blocks contain invokes to EH-pads other than
// landingpads; we don't know how to split those edges yet.
auto *FirstNonPHI = II->getUnwindDest()->getFirstNonPHI();
if (FirstNonPHI->isEHPad() && !isa<LandingPadInst>(FirstNonPHI))
return false;
}
for (Instruction &I : *BB) {
if (const CallInst *CI = dyn_cast<CallInst>(&I)) {
if (CI->cannotDuplicate())
for (Instruction &I : *BB)
if (auto CS = CallSite(&I))
if (CS.cannotDuplicate())
return false;
}
if (I.getType()->isTokenTy() && I.isUsedOutsideOfBlock(BB))
return false;
}
}
return true;
}