RFR: 8333893: Optimization for StringBuilder append boolean & null [v4]

[Claes Redestad]

On Tue, 11 Jun 2024 11:35:28 GMT, Shaojin Wen <duke at openjdk.org> wrote:

>> After PR https://github.com/openjdk/jdk/pull/16245, C2 optimizes stores into primitive arrays by combining values ​​into larger stores.
>> 
>> This PR rewrites the code of appendNull and append(boolean) methods so that these two methods can be optimized by C2.
>
> Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:
> 
>   revert

And what happens when you run that last thing with `-XX:+UnlockDiagnosticVMOptions -XX:DisableIntrinsic=_putCharStringU`?  I believe the intrinsic is basically a handcrafted merge optimization, and might very well be obsolete with the MergeStores optimization in place.

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PR Comment: https://git.openjdk.org/jdk/pull/19626#issuecomment-2162893168