RFR: 8311220: Optimization for StringLatin UpperLower [v7]

[Roger Riggs]

On Mon, 4 Sep 2023 06:50:18 GMT, 温绍锦 <duke at openjdk.org> wrote:

>> # Benchmark Result
>> 
>> 
>> sh make/devkit/createJMHBundle.sh
>> bash configure --with-jmh=build/jmh/jars
>> make test TEST="micro:java.lang.StringUpperLower.*"
>> 
>> 
>> 
>> ## 1. [aliyun_ecs_c8i.xlarge](https://help.aliyun.com/document_detail/25378.html#c8i)
>> * cpu : intel xeon sapphire rapids (x64)
>> 
>> ``` diff
>> -Benchmark                      Mode  Cnt   Score   Error  Units (baseline)
>> -StringUpperLower.lowerToLower  avgt   15  27.180 ± 0.017  ns/op
>> -StringUpperLower.lowerToUpper  avgt   15  47.196 ± 0.066  ns/op
>> -StringUpperLower.mixedToLower  avgt   15  32.307 ± 0.072  ns/op
>> -StringUpperLower.mixedToUpper  avgt   15  44.005 ± 0.414  ns/op
>> -StringUpperLower.upperToLower  avgt   15  32.310 ± 0.033  ns/op
>> -StringUpperLower.upperToUpper  avgt   15  42.053 ± 0.341  ns/op
>> 
>> +Benchmark                      Mode  Cnt   Score   Error  Units (Update 01)
>> +StringUpperLower.lowerToLower  avgt   15  16.964 ± 0.021  ns/op (+60.96%)
>> +StringUpperLower.lowerToUpper  avgt   15  46.491 ± 0.036  ns/op (+1.51%)
>> +StringUpperLower.mixedToLower  avgt   15  35.947 ± 0.254  ns/op (-10.12%)
>> +StringUpperLower.mixedToUpper  avgt   15  41.976 ± 0.326  ns/op (+4.83%)
>> +StringUpperLower.upperToLower  avgt   15  33.466 ± 4.036  ns/op (-3.45%)
>> +StringUpperLower.upperToUpper  avgt   15  17.446 ± 1.036  ns/op (+141.04%)
>> 
>> +Benchmark                      Mode  Cnt   Score   Error  Units (Update 00)
>> +StringUpperLower.lowerToLower  avgt   15  16.976 ± 0.043  ns/op (+60.160)
>> +StringUpperLower.lowerToUpper  avgt   15  46.373 ± 0.086  ns/op (+1.77%)
>> +StringUpperLower.mixedToLower  avgt   15  32.018 ± 0.061  ns/op (+0.9%)
>> +StringUpperLower.mixedToUpper  avgt   15  42.019 ± 0.473  ns/op (+4.72%)
>> +StringUpperLower.upperToLower  avgt   15  32.052 ± 0.051  ns/op (+0.8%)
>> +StringUpperLower.upperToUpper  avgt   15  16.978 ± 0.190  ns/op (+147.69%)
>> 
>> 
>> ## 2. [aliyun_ecs_c8a.xlarge](https://help.aliyun.com/document_detail/25378.html#c8a)
>> * cpu : amd epc genoa (x64)
>> 
>> ``` diff
>> -Benchmark                      Mode  Cnt   Score   Error  Units (baseline)
>> -StringUpperLower.lowerToLower  avgt   15  22.164 ± 0.021  ns/op
>> -StringUpperLower.lowerToUpper  avgt   15  46.113 ± 0.047  ns/op
>> -StringUpperLower.mixedToLower  avgt   15  28.501 ± 0.037  ns/op
>> -StringUpperLower.mixedToUpper  avgt   15  38.782 ± 0.038  ns/op
>> -StringUpperLower.upperToLower  avgt   15  28.625 ± 0.162  ns/op
>> -StringUpperLower.upperToUpper  avgt   15  27.960 ± 0.038  ns/op
>> 
>> +B...
>
> 温绍锦 has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:
> 
>  - Merge branch 'master' of github.com:wenshao/jdk into optimization_for_string_latin1_upper_lower
>  - rename hasNotUpperCaseEx to hasUpperCaseMapping
>  - rename isLowerCaseEx to hasNotUpperCaseEx
>  - use hex literal
>  - add method CharacterDataLatin1#isLowerCaseEx
>  - remove unnecessary code
>  - optimization for StringLatin1 UpperLower

src/java.base/share/classes/java/lang/StringLatin1.java line 423:

> 421:         int first;
> 422:         final int len = value.length;
> 423:         // Now check if there are any characters that need to be changed, or are surrogate

Pre-existing: `, or are surrogate` the mention of surrogate is misleading; this is a latin1 string and cannot contain a surrogate.
Here and in the toLowerCaseEx method.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/14751#discussion_r1317681978