RFR: 8333893: Optimization for StringBuilder append boolean & null [v17]

[Shaojin Wen]

On Sun, 22 Sep 2024 02:03:02 GMT, Chen Liang <liach at openjdk.org> wrote:

> We should declare `count` before `ensureCapacitiyInternal`. Same for append boolean.

Declaring count before ensureCapacityInternal will cause performance regression under x64. It took a lot of time to find this, but the underlying reason is still unclear.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19626#discussion_r1770587530