RFR: 8315856: RISC-V: Use Zacas extension for cmpxchg [v6]

[Fei Yang]

On Fri, 15 Dec 2023 14:51:06 GMT, Ludovic Henry <luhenry at openjdk.org> wrote:

>> 8315856: RISC-V: Use Zacas extension for cmpxchg
>
> Ludovic Henry has updated the pull request incrementally with one additional commit since the last revision:
> 
>   review

Thanks for the update. Seems fine given that it is an experimental feature for now. We will need more thorough tests (jcstress, benchmark, etc.) on real hardware when turning this into a product option.

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Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16910#pullrequestreview-1788143980