RFR: 8320448: Accelerate IndexOf using AVX2 [v34]

[Vladimir Kozlov]

On Thu, 23 May 2024 19:54:39 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 incrementally with one additional commit since the last revision:
> 
>   Addressing review comments

Few suggestions

src/hotspot/cpu/x86/stubGenerator_x86_64.cpp line 4250:

> 4248:   generate_chacha_stubs();
> 4249: 
> 4250:   if ((UseAVX == 2) && EnableX86ECoreOpts && VM_Version::supports_avx2()) {

`#ifdef COMPILER2` around this code to exclude JVMCI only case.

src/hotspot/cpu/x86/stubGenerator_x86_64.hpp line 582:

> 580: 
> 581: #ifdef COMPILER2
> 582:   void generate_string_indexof_stubs(address *fnptrs, StrIntrinsicNode::ArgEncoding ae);

Is it possible to make `generate_string_indexof_stubs()` as local static method in `stubGenerator_x86_64_string.cpp` and pass `StubGenerator*` as argument?
Then you don't to include "opto/intrinsicnode.hpp" here.

src/hotspot/cpu/x86/stubGenerator_x86_64_string.cpp line 2:

> 1: /*
> 2:  * Copyright (c) 2023, Intel Corporation. All rights reserved.

2024 year

src/hotspot/cpu/x86/stubGenerator_x86_64_string.cpp line 27:

> 25: 
> 26: #include "precompiled.hpp"
> 27: #ifdef COMPILER2

You can exclude this file completely from compilation without this `#ifdef` if you prefix the name with `c2_`.
There is code in make files to exclude such files: [JvmFeatures.gmk#L38](https://github.com/openjdk/jdk/blob/master/make/hotspot/lib/JvmFeatures.gmk#L38)

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

PR Review: https://git.openjdk.org/jdk/pull/16753#pullrequestreview-2075150606
PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1612352891
PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1612383969
PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1612365050
PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1612375730