RFR: 8364936: Shenandoah: Switch nmethod entry barriers to conc_instruction_and_data_patch [v3]

Fri Sep 5 17:27:12 UTC 2025

On Wed, 3 Sep 2025 00:37:59 GMT, Cesar Soares Lucas <cslucas at openjdk.org> wrote:

>> Please, review this patch to make nmethod entry barriers use `conc-instruction-and-data-patch` fence mechanics when ShenandoahGC is being used on AArch64. The patch also removes (including from JVMCI interface) the old constant that was being used only by Shenandoah on AArch64.
>> 
>> The patch has been tested with functional and performance benchmarks on AArch64. Improvements in DaCapo and Renaissance benchmarks can be as high as 30%. Maximum critical Jops in SPEC improved by ~10%.
>
> Cesar Soares Lucas has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Make PPC backend to also use concurrent code patching.

@dbriemann - do you have access to a PPC machine that you can use to test this patch? TIA.

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PR Comment: https://git.openjdk.org/jdk/pull/26999#issuecomment-3259209337