<i18n dev> RFR: 8302871: Speed up StringLatin1.regionMatchesCI [v4]

[Eirik Bjorsnos]

On Mon, 20 Feb 2023 15:40:09 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> Eirik Bjorsnos has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Add @bug tag to EqualsIgnoreCase test for correct issue JDK-8302871
>>  - Add @bug tag to EqualsIgnoreCase test for JDK-8302877
>
> src/java.base/share/classes/java/lang/CharacterDataLatin1.java.template line 170:
> 
>> 168:      * @return true if the two bytes are considered equals ignoring case in latin1
>> 169:      */
>> 170:      static boolean equalsIgnoreCase(byte b1, byte b2) {
> 
> Perhaps put this in `CharacterDataLatin1`, keeping it close to toLowerCase/toUpperCase that you're changing to use similar logic with #12623 
> 
> If you apply #12623 first - how much difference does this make on the micro you're adding with this PR?

Is it not already in CharacterDataLatin1?

Here is a comparison of relying on improvements in `CharacterDataLatin1.toUpperCase/toLowerCase` only vs. using `CharacterDataLatin1.equalsIgnoreCase`:

Character.toUpperCase/toLowerCase only:


Benchmark                                  (codePoints)  (size)  Mode  Cnt     Score    Error  Units
RegionMatchesIC.Latin1.regionMatchesIC      ascii-match    1024  avgt   15  1310.582 ± 84.777  ns/op
RegionMatchesIC.Latin1.regionMatchesIC   ascii-mismatch    1024  avgt   15     4.547 ±  0.545  ns/op
RegionMatchesIC.Latin1.regionMatchesIC     number-match    1024  avgt   15   686.947 ± 11.850  ns/op
RegionMatchesIC.Latin1.regionMatchesIC  number-mismatch    1024  avgt   15     3.836 ±  0.634  ns/op
RegionMatchesIC.Latin1.regionMatchesIC       lat1-match    1024  avgt   15  2107.219 ± 17.662  ns/op
RegionMatchesIC.Latin1.regionMatchesIC    lat1-mismatch    1024  avgt   15     4.924 ±  0.829  ns/op


CharacterDataLatin1.equalsIgnoreCase:


Benchmark                                  (codePoints)  (size)  Mode  Cnt     Score    Error  Units
RegionMatchesIC.Latin1.regionMatchesIC      ascii-match    1024  avgt   15   742.467 ± 34.490  ns/op
RegionMatchesIC.Latin1.regionMatchesIC   ascii-mismatch    1024  avgt   15     3.960 ±  0.046  ns/op
RegionMatchesIC.Latin1.regionMatchesIC     number-match    1024  avgt   15   361.158 ± 37.096  ns/op
RegionMatchesIC.Latin1.regionMatchesIC  number-mismatch    1024  avgt   15     4.039 ±  0.521  ns/op
RegionMatchesIC.Latin1.regionMatchesIC       lat1-match    1024  avgt   15  1158.091 ± 41.617  ns/op
RegionMatchesIC.Latin1.regionMatchesIC    lat1-mismatch    1024  avgt   15     4.358 ±  0.123  ns/op

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PR: https://git.openjdk.org/jdk/pull/12632