RFR: 8304245: Speed up CharacterData.of by avoiding bit shifting in the latin1 fast-path test [v2]
Eirik Bjorsnos
duke at openjdk.org
Wed Mar 15 14:31:03 UTC 2023
> By avoiding a bit shift operation for the latin1 fast-path test, we can speed up the `java.lang.CharacterData.of` method by ~25% for latin1 code points.
>
> The latin1 test is currently implemented as `ch >>> 8 == 0`. We can replace this with `ch >= 0 && ch <= 0xFF` for a noticable performance gain (especially for Latin1 code points):
>
> This method is called frequently by various property-determining methods in `java.lang.Character` like `isLowerCase`, `isDigit` etc, so one should expect improvements for all these methods.
>
> Performance is tested using the `Characters.isDigit` benchmark using the digits '0' (decimal 48, in CharacterDataLatin1) and '\u0660' (decimal 1632, in CharacterData00):
>
> Baseline:
>
>
> Benchmark (codePoint) Mode Cnt Score Error Units
> Characters.isDigit 48 avgt 15 0.870 ± 0.011 ns/op
> Characters.isDigit 1632 avgt 15 2.168 ± 0.017 ns/op
>
> PR:
>
>
> Benchmark (codePoint) Mode Cnt Score Error Units
> Characters.isDigit 48 avgt 15 0.654 ± 0.007 ns/op
> Characters.isDigit 1632 avgt 15 2.032 ± 0.019 ns/op
Eirik Bjorsnos has updated the pull request incrementally with one additional commit since the last revision:
Update StringLatin1.canEncode to sync with same test in CharacterData.of
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/13040/files
- new: https://git.openjdk.org/jdk/pull/13040/files/0174440e..0baf690e
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=13040&range=01
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=13040&range=00-01
Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
Patch: https://git.openjdk.org/jdk/pull/13040.diff
Fetch: git fetch https://git.openjdk.org/jdk pull/13040/head:pull/13040
PR: https://git.openjdk.org/jdk/pull/13040
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