RFR: 8374328: Convert simple AtomicAccess uses in gc/shared to use Atomic<T> [v3]

[David Holmes]

On Wed, 7 Jan 2026 14:24:37 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Please review these fairly simple changes to code in gc/shared to use
>> `Atomic<T>` instead of directly using `AtomicAccess`.
>> 
>> This change doesn't eliminate all remaining direct uses of `AtomicAccess` in
>> that directory; there are still a few uses that seem less simple, and maybe
>> some that should stay with direct `AtomicAccess`.
>> 
>> The changes are grouped into a series of commits, as a potential aid to reviewers.
>> 
>> Testing: mach5 tier1-5
>
> Kim Barrett has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains eight additional commits since the last revision:
> 
>  - Merge branch 'master' into simple-gc-shared-atomic
>  - update copyrights
>  - pretouch
>  - WorkerThread control
>  - SuspendibleThreadSet control
>  - GCLocker control
>  - ConcurrentGCThread termination protocol
>  - DeoptimizeNMethodBarriersALot gating counter

Marked as reviewed by dholmes (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/28987#pullrequestreview-3638113084