RFR: 8377713: Shenandoah: Convert ShenandoahReferenceProcessor to use Atomic<T>

[Aleksey Shipilev]

On Tue, 17 Feb 2026 19:29:29 GMT, Ben Taylor <btaylor at openjdk.org> wrote:

> Modernizes the code as has been done in other areas of Shenandoah and G1 GCs.
> 
> The same tier1 tests pass before and after this change on x86_64 and aarch64 linux when run with -XX:+UseShenandoahGC

src/hotspot/share/gc/shenandoah/shenandoahReferenceProcessor.cpp line 522:

> 520:   // Process discovered references
> 521:   uint max_workers = ShenandoahHeap::heap()->max_workers();
> 522:   uint worker_id = _iterate_discovered_list_id.add_then_fetch(1U, memory_order_relaxed) - 1;

Here and later: use `fetch_then_add`, and drop `-1`?

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PR Review Comment: https://git.openjdk.org/jdk/pull/29767#discussion_r2820973819