RFR: 8351565: Implement JEP 502: Stable Values (Preview) [v53]

[Per Minborg]

On Thu, 10 Apr 2025 10:26:36 GMT, Per Minborg <pminborg at openjdk.org> wrote:

>> Implement JEP 502.
>> 
>> The PR passes tier1-tier3 tests.
>
> Per Minborg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Improve docs as per comments

> > ```
> > 
> > I will take a look at it.
> > ```
> 
> As i said in another mail to core-lib this morning, it seems that the field storing the hashcode of String is not marked with @stable. That's may be the issue.

Yes. I can confirm that this is the root cause of the problem:


Benchmark                         Mode  Cnt    Score    Error  Units
Tmp.confinedStableFunctionLoop    avgt    5  153.522 ±  6.707  ns/op
Tmp.confinedStableMapElementLoop  avgt    5  142.780 ±  4.077  ns/op
Tmp.confinedStableMapLoop         avgt    5  157.815 ± 17.250  ns/op
Tmp.confinedStableValueLoop       avgt    5  142.940 ±  2.721  ns/op
Tmp.confinedUnmodifiableMapLoop   avgt    5  142.542 ± 10.049  ns/op

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PR Comment: https://git.openjdk.org/jdk/pull/23972#issuecomment-2793199126