[jdk21u-dev] Withdrawn: 8311220: Optimization for StringLatin UpperLower

[duke]

On Thu, 17 Jul 2025 12:01:12 GMT, Roman Marchenko <rmarchenko at openjdk.org> wrote:

> This is backport of "[JDK-8311220](https://bugs.openjdk.org/browse/JDK-8311220) Optimization for StringLatin UpperLower"
> 
> It seems good to have it backported as I see improvements even locally on my i7-12700H (benchmarks command line was taken from original PR):
> 
> sh make/devkit/createJMHBundle.sh
> bash configure --with-jmh=build/jmh/jars
> make test TEST="micro:java.lang.StringUpperLower.*"
> 
> ----- Baseline JDK21
> Benchmark                      Mode  Cnt   Score   Error  Units
> StringUpperLower.lowerToLower  avgt   15  24.146 ± 0.216  ns/op
> StringUpperLower.lowerToUpper  avgt   15  43.720 ± 2.689  ns/op
> StringUpperLower.mixedToLower  avgt   15  27.335 ± 1.120  ns/op
> StringUpperLower.mixedToUpper  avgt   15  43.239 ± 3.731  ns/op
> StringUpperLower.upperToLower  avgt   15  28.310 ± 1.557  ns/op
> StringUpperLower.upperToUpper  avgt   15  35.032 ± 1.840  ns/op
> 
> ----- Backported
> Benchmark                      Mode  Cnt   Score   Error  Units
> StringUpperLower.lowerToLower  avgt   15  13.890 ± 0.786  ns/op
> StringUpperLower.lowerToUpper  avgt   15  38.636 ± 2.103  ns/op
> StringUpperLower.mixedToLower  avgt   15  28.087 ± 1.639  ns/op
> StringUpperLower.mixedToUpper  avgt   15  33.970 ± 0.502  ns/op
> StringUpperLower.upperToLower  avgt   15  28.394 ± 1.443  ns/op
> StringUpperLower.upperToUpper  avgt   15  17.347 ± 0.578  ns/op

This pull request has been closed without being integrated.

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PR: https://git.openjdk.org/jdk21u-dev/pull/1988