[lworld] RFR: 8376171: [lworld] Enable storing the hash code in the mark word of value objects [v3]

[Tobias Hartmann]

On Tue, 27 Jan 2026 14:00:54 GMT, Paul Hübner <phubner at openjdk.org> wrote:

>>> how can we guarantee that between the CAS L806 and this cast L809 another thread hasn't updated the hash? Or do we not care if that's the case and up to the application to handle?
>> 
>> But the same value object always has the same hash, right? So it does not matter if another thread already updated the hash.
>
> Right, I totally forgot we were in a Valhalla-path. That rationale makes sense to me. Thanks!

FTR: This only holds once [PR1987](git.openjdk.org/valhalla/pull/1987) is in.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1954#discussion_r2735194893