RFR: 8336831: Optimize StringConcatHelper.simpleConcat

[Shaojin Wen]

On Fri, 19 Jul 2024 13:10:43 GMT, Shaojin Wen <duke at openjdk.org> wrote:

> Currently simpleConcat is implemented using mix and prepend, but in this simple scenario, it can be implemented in a simpler way and can improve performance.

Below are the performance numbers running on a MacBook M1 Pro, which is 8.71% faster

-Benchmark                             (intValue)  Mode  Cnt  Score   Error  Units
-StringConcat.concatMethodConstString        4711  avgt   15  5.499 ? 0.046  ns/op

+Benchmark                             (intValue)  Mode  Cnt  Score   Error  Units
+StringConcat.concatMethodConstString        4711  avgt   15  5.058 ? 0.012  ns/op +8.71%

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PR Comment: https://git.openjdk.org/jdk/pull/20253#issuecomment-2239120831