On Wed, 29 Nov 2023 15:01:32 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 incrementally with one additional
> commit since the last revision:
>
> Only use optimization when EnableX86ECoreOpts is true
src/hotspot/cpu/x86/stubGenerator_x86_64_string.cpp line 42:
> 40: // 2. Broadcast the last byte of the needle to a different ymm register
> 41: // 3. Compare the first-byte ymm register to the first 32 bytes of the
> haystack
> 42: // 4. Compare the last-byte register to the 32 bytes of the haystack at
> the (k-1)st position
It would be good to mention that k is the length of the needle.
src/hotspot/cpu/x86/stubGenerator_x86_64_string.cpp line 117:
> 115:
> /******************************************************************************/
> 116:
> 117: void StubGenerator::loop_helper(int size, Label& bailout, Label&
> loop_top) {
Let us name this method as string_indexof_loop_helper() instead of just
loop_helper().
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1409626570
PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1409623608
