RFR: 8257498: Remove useless skeleton predicates [v5]

[Tobias Hartmann]

On Mon, 25 Jan 2021 09:45:52 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> This enhancement removes useless skeleton predicates in the same way as we already remove normal useless predicates in `PhaseIdealLoop::eliminate_useless_predicates()`.
>> 
>> Thanks,
>> Christian
>
> Christian Hagedorn has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:
> 
>  - Merge master due to conflict
>  - Revert get_skeleton_predicates again
>  - Fix removal from global list and update get_skeleton_predicates
>  - Add handling of Deoptimization::Reason_profile_predicate
>  - 8257498: Remove useless skeleton predicates

Looks good to me.

src/hotspot/share/opto/loopnode.cpp line 3597:

> 3595: 
> 3596:   for (int i = C->skeleton_predicate_count(); i > 0; i--) {
> 3597:     const int idx = i - 1;

Could be removed for consistency with above code.

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Marked as reviewed by thartmann (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/2075