RFR: 8377126: Shenandoah: Convert ShenandoahVerifier related code to use Atomic<T> [v2]

[duke]

On Thu, 5 Feb 2026 16:54:34 GMT, Ben Taylor <btaylor at openjdk.org> wrote:

>> Modernizes ShenandoahVerifier code by replacing `AtomicAccess` methods with `Atomic<T>` types.
>> 
>> Tier1 test results on x86_64 linux are the same before and after this change when running with `TEST_VM_OPTS=-XX:+UseShenandoahGC`.
>
> Ben Taylor has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Restore dropped  in shenandoahVerifier

@benty-amzn 
Your change (at version 87229bad6ec3d50bce64794c80b08c211a60613e) is now ready to be sponsored by a Committer.

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PR Comment: https://git.openjdk.org/jdk/pull/29576#issuecomment-3856264690