[11u] RFR 8245512: CRC32 optimization using AVX512 instructions

[Viswanathan, Sandhya]

Thanks a lot Vladimir for review and link to the process. I requested the backport in JBS.

Best Regards,
Sandhya

-----Original Message-----
From: Vladimir Kozlov <vladimir.kozlov at oracle.com> 
Sent: Thursday, December 10, 2020 3:07 PM
To: Viswanathan, Sandhya <sandhya.viswanathan at intel.com>; jdk-updates-dev at openjdk.java.net; hotspot-compiler-dev at openjdk.java.net
Subject: Re: [11u] RFR 8245512: CRC32 optimization using AVX512 instructions

Changes are fine but you need to follow process:

http://openjdk.java.net/projects/jdk-updates/approval.html

Also it is performance improvement which may not be accepted.

Regards,
Vladimi

On 12/10/20 1:00 PM, Viswanathan, Sandhya wrote:
> I would like to backport the CRC32 optimization using AVX512 instructions to JDK 11u.
> This optimization was introduced in JDK 15.
> 
> JBS: https://bugs.openjdk.java.net/browse/JDK-8245512
> Webrev: http://cr.openjdk.java.net/~sviswanathan/8245512/webrev.00/
> 
> Only one change was needed to the original patch in src/hotspot/cpu/x86/assembler_x86.cpp.
> 
> The following in Assembler::blendvpb(), line 7908:
> 
>   emit_int24(0x4C, (0xC0 | encode), (0xF0 & src2_enc << 4)); was 
> replaced by equivalent:
>    emit_int8((unsigned char)0x4C);
> emit_int8((unsigned char)(0xC0 | encode)); emit_int8((unsigned 
> char)(0xF0 & src2_enc<<4));
> 
> The patch applies cleanly otherwise.
> 
> Please review this backport to 11u.
> 
> Best Regards,
> Sandhya
>