RFR: 8333893: Optimization for StringBuilder append boolean & null [v8]

[Shaojin Wen]

On Thu, 13 Jun 2024 02:06:42 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 two additional commits since the last revision:
> 
>  - rename benchmark
>  - code format & use long address

I also found that the `StringBuilders.appendWithBool8Latin1` case has performance regression on Intel® Xeon® Emerald Rapids and AMD EPYCTM Genoa.

I haven't found the reason yet

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PR Comment: https://git.openjdk.org/jdk/pull/19626#issuecomment-2165434407