[15] RFR(M): 8245512: CRC32 optimization using AVX512 instructions

[Rukmannagari, Shravya]

Hi Vladimir,
The compiler/cpuflags/TestSSE4Disabled.java jtreg test was failing without the check. 
This test is run with SSE=3 as:
run main/othervm -Xcomp -XX:UseSSE=3 compiler.cpuflags.TestSSE4Disabled
Without the UseSSE > 3 check, the JVM tries to generate the new AVX512 CRC32 stub.

Thanks,
Shravya.

-----Original Message-----
From: Vladimir Kozlov <vladimir.kozlov at oracle.com> 
Sent: Tuesday, June 2, 2020 5:00 PM
To: Rukmannagari, Shravya <shravya.rukmannagari at intel.com>; 'hotspot compiler' <hotspot-compiler-dev at openjdk.java.net>
Cc: Tucker, Greg B <greg.b.tucker at intel.com>
Subject: Re: [15] RFR(M): 8245512: CRC32 optimization using AVX512 instructions

On 6/2/20 3:56 PM, Rukmannagari, Shravya wrote:
> Hi Vladimir,
> Thanks a lot for the review. I have modified the patch as per your comments. The CRC32 code is now in macroAssembler_x86.cpp.
> http://cr.openjdk.java.net/~srukmannagar/CRC32/webrev.02/

Why you added UseSSE check in stubGenerator_x86_64.cpp?

+    if (UseSSE > 3 && VM_Version::supports_avx512_vpclmulqdq() &&

> 
> The stubGenerator_x86_64.cpp would be verified only for 64-bit builds. I have verified the 32-bit builds and also ran the test cases to ensure no issues or failures.

You are right about this.

Thanks,
Vladimir

> Please let me know if you have questions or comments.
> 
> Thanks,
> Shravya.
> 
> -----Original Message-----
> From: Vladimir Kozlov <vladimir.kozlov at oracle.com>
> Sent: Monday, June 1, 2020 2:36 PM
> To: Rukmannagari, Shravya <shravya.rukmannagari at intel.com>; 'hotspot compiler' <hotspot-compiler-dev at openjdk.java.net>
> Cc: Tucker, Greg B <greg.b.tucker at intel.com>
> Subject: Re: [15] RFR(M): 8245512: CRC32 optimization using AVX512 instructions
> 
> Hi Shravya,
> 
> Why you put new CRC32 avx512 code into macroAssembler_x86_aes.cpp file?
> This file is used only for AES intrinsic code - nothing else should be there.
> 
> If you think CRC32 code is too large for macroAssembler_x86.cpp I would suggest to move all CRC32 code, old and new, into new macroAssembler_x86_crc32.cpp file.
> 
> I see that you want to implement new code only for 64 bit which is fine and you guarded it correctly wiht #ifrdef _LP64.
> But you forgot guard in stubGenerator_x86_64.cpp which will cause build failure for 32-bit.
> 
> It is difficult to judge the implementation code. I hope you ran all tests for it.
> 
> Thanks,
> Vladimir
> 
> On 5/20/20 4:01 PM, Rukmannagari, Shravya wrote:
>> Hi All,
>>
>> We would like to contribute optimizations for CRC32 algorithm for upcoming Intel x86_64 platforms.
>>
>>
>>
>> Contributors:
>>
>> Shravya Rukmannagari(shravya.rukmannagari at intel.com)
>>
>> Greg B Tucker(greg.b.tucker at intel.com)
>>
>>
>>
>> I have tested the patch to confirm correctness and performance. The patch also passes compiler/jtreg tests.
>>
>>
>>
>> Please take a look and let me know if you have any questions or comments.
>>
>>
>>
>> Bug Id: https://bugs.openjdk.java.net/browse/JDK-8245512
>>
>> https://cr.openjdk.java.net/~srukmannagar/CRC32/webrev.01/
>>
>>
>>
>> Regards,
>>
>> Shravya Rukmannagari
>>