On Sat, 23 Mar 2024 02:16:57 GMT, Scott Gibbons <sgibb...@openjdk.org> wrote:
>> Re-write the IndexOf code without the use of the pcmpestri instruction, only >> using AVX2 instructions. This change accelerates String.IndexOf on average >> 1.3x for AVX2. The benchmark numbers: >> >> >> Benchmark Score >> Latest >> StringIndexOf.advancedWithMediumSub 343.573 317.934 >> 0.925375393x >> StringIndexOf.advancedWithShortSub1 1039.081 1053.96 >> 1.014319384x >> StringIndexOf.advancedWithShortSub2 55.828 110.541 >> 1.980027943x >> StringIndexOf.constantPattern 9.361 11.906 >> 1.271872663x >> StringIndexOf.searchCharLongSuccess 4.216 4.218 >> 1.000474383x >> StringIndexOf.searchCharMediumSuccess 3.133 3.216 >> 1.02649218x >> StringIndexOf.searchCharShortSuccess 3.76 3.761 >> 1.000265957x >> StringIndexOf.success 9.186 >> 9.713 1.057369911x >> StringIndexOf.successBig 14.341 46.343 >> 3.231504079x >> StringIndexOfChar.latin1_AVX2_String 6220.918 12154.52 >> 1.953814533x >> StringIndexOfChar.latin1_AVX2_char 5503.556 5540.044 >> 1.006629895x >> StringIndexOfChar.latin1_SSE4_String 6978.854 6818.689 >> 0.977049957x >> StringIndexOfChar.latin1_SSE4_char 5657.499 5474.624 >> 0.967675646x >> StringIndexOfChar.latin1_Short_String 7132.541 >> 6863.359 0.962260014x >> StringIndexOfChar.latin1_Short_char 16013.389 16162.437 >> 1.009307711x >> StringIndexOfChar.latin1_mixed_String 7386.123 14771.622 >> 1.999915517x >> StringIndexOfChar.latin1_mixed_char 9901.671 9782.245 >> 0.987938803 > > Scott Gibbons has updated the pull request with a new target base due to a > merge or a rebase. The pull request now contains 46 commits: > > - Merge branch 'openjdk:master' into indexof > - Cleaned up, ready for review > - Pre-cleanup code > - Add JMH. Add 16-byte compares to arrays_equals > - Better method for mask creation > - Merge branch 'openjdk:master' into indexof > - Most cleanup done. > - Remove header dependency > - Works - needs cleanup > - Passes tests. > - ... and 36 more: https://git.openjdk.org/jdk/compare/bc739639...e079fc12 Hi, in Netty, we have our own AsciiString::indexOf based on SWAR techniques, which is manually loop unrolling the head processing (first < 8 bytes) to artificially make sure the branch predictor got different branches to care AND JIT won't make it wrong. We have measured (I can provide a link of the benchmark and results, If you are interested) that it delivers a much better performance on tiny strings and makes a smoother degradation vs perfectly aligned string length as well. Clearly this tends to be much visible if the input strings have shuffled delimiter positions, to make the branch prediction misses more relevant. ------------- PR Comment: https://git.openjdk.org/jdk/pull/16753#issuecomment-2016432345
