RFR: 8349183: [BACKOUT] Optimization for StringBuilder append boolean & null [v2]

[Claes Redestad]

On Mon, 3 Feb 2025 17:04:33 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> Jaikiran Pai has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains two new commits since the last revision:
>> 
>>  - Revert "8333893: Optimization for StringBuilder append boolean & null"
>>    
>>    This reverts commit 5890d9438bbde88b89070052926a2eafe13d7b42.
>>  - Revert "8343650: Reuse StringLatin1::putCharsAt and StringUTF16::putCharsAt"
>>    
>>    This reverts commit 74ae3c688b37e693e20eb4e17c631897c5464400.
>
> This concurrency problem also exists in the UTF16 scenario, so why only change to Latin1 here?

@wenshao this re-instates the `checkBoundsBeginEnd(i, end, value);` in the UTF16 case that was removed by the issue being backed out, so we get back to a state where we have appropriate bounds checks on all array accesses.

An alternative to this backout would be to add `checkBoundsBeginEnd(i, end, value);` to all the `putCharsAt` methods, though it's unclear if that would undo the performance advantage. Better then to backout and - if possible - redo with a closer examination of the performance with a safer construct.

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PR Comment: https://git.openjdk.org/jdk/pull/23420#issuecomment-2631644364