[PATCH] D30633: [BPI] Reduce the probability of unreachable edge to minimal value greater than 0

[Xinliang David Li via llvm-commits]

It is the BFI that does that.
See BlockFrequencyInfoImpl<BT>::propagateMassToSuccessors, and addToDist
method which turns 0 weight from BP into 1.

Clang FE  does this indirectly for FE based PGO -- all weights after
scaling will be added with 1.    User profile annotation will remain
unchanged.

David


On Tue, May 16, 2017 at 11:01 PM, Serguei Katkov via Phabricator <
reviews at reviews.llvm.org> wrote:

> skatkov added a comment.
>
> Hello guys,
>
> you are saying that BFI bumps the zero probability but I still see in
> MachineBlockPlacement pass that it actively uses branch probabilities and
> it seems that they are original ones. At least I see the zero probability
> if I set it in metadata.
>
> Could you please point me to the place where it is bumped?
>
> Thank you,
> Serguei.
>
>
> https://reviews.llvm.org/D30633
>
>
>
>
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