On Fri, 24 May 2024 20:47:23 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:
> 
>   Review comments.

src/hotspot/cpu/x86/c2_stubGenerator_x86_64_string.cpp line 1122:

> 1120: // eq_mask - The bit mask returned that holds the result of the 
> comparison
> 1121: // rTmp - a temporary register
> 1122: // rTmp2 - a temporary register

There is no rtmp, rtmp2 here.

src/hotspot/cpu/x86/c2_stubGenerator_x86_64_string.cpp line 1129:

> 1127: // _masm - Current MacroAssembler instance pointer
> 1128: //
> 1129: // If (n - k) < 32, need to handle reading past end of haystack

Don't see (n-k) < 32 being handled in this function.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1614091336
PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1614092828

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