RFR: 8374328: Convert simple AtomicAccess uses in gc/shared to use Atomic<T> [v2]

[David Holmes]

On Fri, 2 Jan 2026 10:11:58 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 incrementally with one additional commit since the last revision:
> 
>   update copyrights

This all looks fine to me. Thanks.

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Marked as reviewed by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28987#pullrequestreview-3629738175