RFR: 8302818: Optimize wrapper sets and immutable sets of Enums [v5]

[Tingjun Yuan]

On Tue, 21 Mar 2023 23:41:44 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> Tingjun Yuan has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Set.copyOf: need defensive copy
>
> If this level of complexity is indeed needed to get whatever improvement you're after then I don't see how this can be worth its weight. Microbenchmarking might help support your case here, but assessing the potential performance costs from gradually increasing the number of classes floating around at various call sites in arbitrary applications is hard. Thus it is something we need to be very careful not to do without solid evidence.

@cl4es @stuart-marks Thanks for reviewing and commenting. I'm converting this PR to draft until I finish evaluating whether these changes are necessary or not.

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PR Comment: https://git.openjdk.org/jdk/pull/12498#issuecomment-1479891838