RFR: 8266332: Adler32 intrinsic for x86 64-bit platforms [v10]

[Vladimir Kozlov]

On Mon, 17 May 2021 18:57:28 GMT, Xubo Zhang <github.com+58006833+xbzhang99 at openjdk.org> wrote:

>> Implement Adler32 intrinsic for x86 64-bit platform using vector instructions.
>> 
>> The benchmark test/micro/org/openjdk/bench/java/util/TestAdler32.java is contributed by Pengfei Li (pli, Pengfei.Li at arm.com).
>> 
>> For this benchmark,  the optimization shows ~5x improvement.
>> 
>> Base:
>> Benchmark (count) Mode Cnt Score Error Units
>> TestAdler32Perf.testAdler32Update 64 avgt 25 0.084 ± 0.001 us/op
>> TestAdler32Perf.testAdler32Update 128 avgt 25 0.104 ± 0.001 us/op
>> TestAdler32Perf.testAdler32Update 256 avgt 25 0.146 ± 0.002 us/op
>> TestAdler32Perf.testAdler32Update 512 avgt 25 0.226 ± 0.002 us/op
>> TestAdler32Perf.testAdler32Update 1024 avgt 25 0.390 ± 0.005 us/op
>> TestAdler32Perf.testAdler32Update 2048 avgt 25 0.714 ± 0.007 us/op
>> TestAdler32Perf.testAdler32Update 4096 avgt 25 1.359 ± 0.014 us/op
>> TestAdler32Perf.testAdler32Update 8192 avgt 25 2.751 ± 0.023 us/op
>> TestAdler32Perf.testAdler32Update 16384 avgt 25 5.494 ± 0.077 us/op
>> TestAdler32Perf.testAdler32Update 32768 avgt 25 11.058 ± 0.160 us/op
>> TestAdler32Perf.testAdler32Update 65536 avgt 25 22.198 ± 0.319 us/op
>> 
>> 
>> With patch:
>> Benchmark (count) Mode Cnt Score Error Units
>> TestAdler32Perf.testAdler32Update 64 avgt 25 0.020 ± 0.001 us/op
>> TestAdler32Perf.testAdler32Update 128 avgt 25 0.025 ± 0.001 us/op
>> TestAdler32Perf.testAdler32Update 256 avgt 25 0.031 ± 0.001 us/op
>> TestAdler32Perf.testAdler32Update 512 avgt 25 0.048 ± 0.001 us/op
>> TestAdler32Perf.testAdler32Update 1024 avgt 25 0.078 ± 0.001 us/op
>> TestAdler32Perf.testAdler32Update 2048 avgt 25 0.139 ± 0.002 us/op
>> TestAdler32Perf.testAdler32Update 4096 avgt 25 0.262 ± 0.004 us/op
>> TestAdler32Perf.testAdler32Update 8192 avgt 25 0.524 ± 0.010 us/op
>> TestAdler32Perf.testAdler32Update 16384 avgt 25 1.017 ± 0.022 us/op
>> TestAdler32Perf.testAdler32Update 32768 avgt 25 2.058 ± 0.052 us/op
>> TestAdler32Perf.testAdler32Update 65536 avgt 25 3.994 ± 0.013 us/op
>
> Xubo Zhang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove -XX:+UseAdler32Intrinsics, as it will fail on non-supported platforms

I have 2 comments.

src/hotspot/cpu/x86/macroAssembler_x86.hpp line 1322:

> 1320:     Assembler::vpmulld(dst, nds, src, vector_len);
> 1321:   }
> 1322:   void vpmulld(XMMRegister dst, XMMRegister nds, AddressLiteral src, int vector_len, Register scratch_reg = rscratch1);

Looks like my comment was lost.
I see only last version of method is used in stub. Why you need additional 2 wrapper methods?
Also the code always pass `scratch_reg` - you don't need to set default value.

src/hotspot/cpu/x86/vm_version_x86.cpp line 907:

> 905:     }
> 906:   } else if (UseAdler32Intrinsics) {
> 907:     if (!FLAG_IS_DEFAULT(UseAdler32Intrinsics))

Add `{}`.

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

Changes requested by kvn (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/3806