RFR: 8316645: RISC-V: Remove dependency on libatomic by adding cmpxchg 1b

[Fei Yang]

On Tue, 26 Sep 2023 12:04:49 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

> Hi all, please consider.
> 
> latomic is used for non native atomic operation which causes problems with extra dependency.
> This have been fixed in recent gcc, so latomic is no longer needed.
> 
> Added new gtest, passes t1 on vf2/qemu.

That looks great. Thanks.

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Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/15919#pullrequestreview-1649995903