RFR: 8376119: G1: Convert volatiles in G1CMMarkStack to Atomic<T>

[Kim Barrett]

On Thu, 22 Jan 2026 15:35:05 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   please review this conversion of volatiles that do not use any `AtomicAccess` method in `G1CMMarkStack` but are marked as such to indicate potential concurrency when accessing them. Typically we do some phased access, i.e. one (single-threaded) phase writes them, another only reads from them.
> 
> Testing: gha
> 
> Thanks,
>   Thomas

Looks good.

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Marked as reviewed by kbarrett (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/29365#pullrequestreview-3699153144