RFR: 8372650: Convert GenericWaitBarrier to use Atomic<T>

[Kim Barrett]

On Thu, 27 Nov 2025 10:28:26 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Please review this change to GenericWaitBarrier to use Atomic rather than
>> directly applying AtomicAccess to volatile members.
>> 
>> Testing: mach5 tier1-5
>
> src/hotspot/share/utilities/waitBarrier_generic.cpp line 199:
> 
>> 197:     }
>> 198:   }
>> 199:   assert(_outstanding_wakeups.load_acquire() == 0, "Post disarm: Should not have outstanding wakeups");
> 
> Does not have to be `_acquire`, original load is relaxed.

Oops. Will fix.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28527#discussion_r2570824516