RFR: JDK-8320448 Accelerate IndexOf using AVX2 [v14]

[Francesco Nigro]

On Sat, 23 Mar 2024 02:16:57 GMT, Scott Gibbons <sgibbons at 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

Sure thing: https://github.com/netty/netty/pull/13534#issuecomment-1685247165

It's the comparison with String::indexOf while the impl is: https://github.com/netty/netty/blob/3a3f9d13b129555802de5652667ca0af662f554e/buffer/src/main/java/io/netty/buffer/ByteBufUtil.java#L590

-------------

PR Comment: https://git.openjdk.org/jdk/pull/16753#issuecomment-2016576139