RFR: 8339643: Port JEP 404 to RISC-V

[William Kemper]

On Fri, 6 Sep 2024 11:18:35 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)

Looks good to me. Thank you!

Requesting another reviewer for platform specific code.

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

Marked as reviewed by wkemper (Committer).

PR Review: https://git.openjdk.org/shenandoah/pull/493#pullrequestreview-2301393337
PR Comment: https://git.openjdk.org/shenandoah/pull/493#issuecomment-2347219496