[PATCH] D65310: [JumpThreading] In updatePredecessorProfileMetadata, stop searching predecessor when the current bb is an unreachable single bb loop

[Wei Mi via llvm-commits]

On Fri, Jul 26, 2019 at 11:34 AM Eli Friedman via Phabricator <
reviews at reviews.llvm.org> wrote:

> efriedma added subscribers: NutshellySima, brzycki.
> efriedma added a comment.
>
> Please rebase against trunk.
>
>
>
> ================
> Comment at: llvm/lib/Transforms/Scalar/JumpThreading.cpp:1214
>      if (PN->getParent() == BB && isa<BranchInst>(BB->getTerminator()))
> -      updatePredecessorProfileMetadata(PN, BB);
> +      updatePredecessorProfileMetadata(PN, BB, DTU->getDomTree());
>
> ----------------
> Calling getDomTree() here is expensive; it flushes all updates in the
> DomTreeUpdater.
>
>
Or I can detect loop using a set keeping nodes which have been visited.
Whenever SinglePredBB is seen in the set, stop searching.


>
> Repository:
>   rL LLVM
>
> CHANGES SINCE LAST ACTION
>   https://reviews.llvm.org/D65310/new/
>
> https://reviews.llvm.org/D65310
>
>
>
>
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