RFR: 8372285: G1: Micro-optimize x86 barrier code [v4]

[Aleksey Shipilev]

On Fri, 21 Nov 2025 18:29:57 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 10 additional commits since the last revision:
>> 
>>  - Adjust label name
>>  - Merge branch 'master' into JDK-8372285-g1-barrier-micro
>>  - Make some backward branches explicitly short
>>  - Comment
>>  - Shorten a few more branches
>>  - Also reflow generate_pre_barrier_slow_path, so it is obvious the branches are short
>>  - More touchups
>>  - Also optimize queue insertion
>>  - Touchups
>>  - WIP
>
> Comments.

@vnkozlov, are you happy with this version?

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PR Comment: https://git.openjdk.org/jdk/pull/28446#issuecomment-3576335343