RFR: 8360654: AArch64: Remove redundant dmb from C1 compareAndSet [v5]

[Andrew Haley]

On Thu, 20 Nov 2025 14:17:52 GMT, Ruben <duke at openjdk.org> wrote:

> > It would be best to concentrate on eliminating trailing DMB from C1
> 
> Sure, I will consider the C2 to be outside the scope.
> 
> Similarly, there are references for `atomic_addal` and `atomic_addalw` in the C2. I initially expected these to be used in codegen for the above test, however it doesn't happen - apparently because the function isn't an intrinsic candidate.
> 
> https://github.com/openjdk/jdk/blob/f125c76f5b53d90a09f58c22d6def7d843feaa50/src/java.base/share/classes/jdk/internal/misc/Unsafe.java#L2503-L2511

Mmm, perhaps.

> > because there are a few cases that should be handled.
> 
> I haven't yet looked in details into other cases in C1 - presumably, an optimization similar to #26748 should be possible for stores; this would need further investigation.
> 
> However, is there anything else that should be handled within this pull request?

I don't think so.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/26000#discussion_r2546525113