RFR: 8339643: Port JEP 404 to RISC-V [v2]

[Kelvin Nilsen]

On Fri, 13 Sep 2024 03:47:46 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> The riscv64 implementation of [JDK-8337511](https://bugs.openjdk.org/browse/JDK-8337511) Implement JEP-404: Generational Shenandoah (Experimental).
>> This is mainly adapted from the changes in aarch64.
>> 
>> Testing
>> - [x] Gtest (release & fastdebug)
>> - [x] hotspot_gc_shenandoah (release & fastdebug)
>
> Fei Yang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Review

Marked as reviewed by kdnilsen (Committer).

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

PR Review: https://git.openjdk.org/shenandoah/pull/493#pullrequestreview-2303934044