RFR: 8311220: Optimization for StringLatin UpperLower [v8]

[Claes Redestad]

On Mon, 18 Sep 2023 03:00:25 GMT, Chen Liang <liach at openjdk.org> wrote:

>> 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 ten additional commits since the last revision:
>> 
>>  - Merge remote-tracking branch 'upstream/master' into optimization_for_string_latin1_upper_lower
>>  - Merge branch 'master' into optimization_for_string_latin1_upper_lower
>>  - 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/CharacterDataLatin1.java.template line 93:
> 
>> 91:     }
>> 92: 
>> 93:     boolean hasUpperCaseMapping(int ch) {
> 
> This method is incorrectly named; it actually tests that a char has no upper case mapping. I recommend fixing this by keeping the method name while removing the double `!` at this return and at the if down below to simplify the logic.

I'd have preferred @liach's solution (remove the double negative and keeping the method with name unchanged) but this is OK too.

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PR Review Comment: https://git.openjdk.org/jdk/pull/14751#discussion_r1328567080