RFR: 8342382: Implement JEP 522: G1 GC: Improve Throughput by Reducing Synchronization [v59]

[Thomas Schatzl]

On Tue, 16 Sep 2025 07:38:56 GMT, Fei Yang <fyang at openjdk.org> wrote:

>>> @tschatzl : Hi, would you mind adding a small cleanup change for riscv? This also adds back the assertion about the registers. Still test good on linux-riscv64 platform. [riscv-addon.diff.txt](https://github.com/user-attachments/files/22356611/riscv-addon.diff.txt)
>> 
>> This is the `end` -> `count` transformation in the barrier I suggested earlier for RISC-V, isn't it? Thanks for contributing that, but would you mind me holding off this until @theRealAph acks that similar change for aarch64? It would be unfortunate imo if the implementations diverge too much.
>
>> > @tschatzl : Hi, would you mind adding a small cleanup change for riscv? This also adds back the assertion about the registers. Still test good on linux-riscv64 platform. [riscv-addon.diff.txt](https://github.com/user-attachments/files/22356611/riscv-addon.diff.txt)
>> 
>> This is the `end` -> `count` transformation in the barrier I suggested earlier for RISC-V, isn't it? Thanks for contributing that, but would you mind me holding off this until @theRealAph acks that similar change for aarch64? It would be unfortunate imo if the implementations diverge too much.
> 
> Yes, sure! The purpose is to minimize the difference to avoid possible issues in the future.

@RealFYang : going to wait for the response of @theRealAph about the `end->count` matter until early next week, otherwise I'll move this change to cleanups/further enhancements like (JDK-8352069)[https://bugs.openjdk.org/browse/JDK-8352069] already planned.
Just want to be "done" at some point with this change :)

-------------

PR Comment: https://git.openjdk.org/jdk/pull/23739#issuecomment-3305851845