RFR: 8357258: x86: Improve receiver type profiling reliability [v10]

[Aleksey Shipilev]

On Mon, 5 Jan 2026 06:38:07 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> See the bug for discussion what issues current machinery has. 
>> 
>> This PR executes the plan outlined in the bug:
>>  1. Common the receiver type profiling code in interpreter and C1
>>  2. Rewrite receiver type profiling code to only do atomic receiver slot installations
>>  3. Trim `C1OptimizeVirtualCallProfiling` to only claim slots when receiver is installed 
>> 
>> This PR does _not_ do atomic counter updates themselves, as it may have much wider performance implications, including regressions. This PR should be at least performance neutral.
>> 
>> Additional testing:
>>   - [x] Linux x86_64 server fastdebug, `compiler/`
>>   - [x] Linux x86_64 server fastdebug, `all`
>
> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 23 commits:
> 
>  - Merge branch 'master' into JDK-8357258-x86-c1-optimize-virt-calls
>  - Merge branch 'master' into JDK-8357258-x86-c1-optimize-virt-calls
>  - Merge branch 'master' into JDK-8357258-x86-c1-optimize-virt-calls
>  - More comments
>  - Tighten up the comments
>  - Simplify third case: no need to loop, just restart the search
>  - Actually have a second "fast" case: receiver is not found in the table, and the table is full
>  - Pushing/popping for rare CAS path is counter-productive
>  - Merge branch 'master' into JDK-8357258-x86-c1-optimize-virt-calls
>  - Tighten up some more
>  - ... and 13 more: https://git.openjdk.org/jdk/compare/6eaabed5...e4a4719f

Remerged from master, re-ran `tier1` and `hotspot_compiler` tests on Linux x86_64, all clean. There is an unrelated GHA infra failure (https://github.com/openjdk/jdk/pull/29030), which IMO does not block the integration, as at least Windows x86_64 passed in GHA, and Linux x86_64 passes locally.

Here goes.

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PR Comment: https://git.openjdk.org/jdk/pull/25305#issuecomment-3709622490
PR Comment: https://git.openjdk.org/jdk/pull/25305#issuecomment-3709623137