RFR: JDK-8216437 : PPC64: Add intrinsic for GHASH algorithm [v19]

[Suchismith Roy]

On Wed, 5 Feb 2025 14:42:17 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> Suchismith Roy has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   adapt Condition registers
>
> src/hotspot/cpu/ppc/stubGenerator_ppc.cpp line 655:
> 
>> 653:   // https://web.archive.org/web/20110609115824/https://software.intel.com/file/24918
>> 654:   //
>> 655:   Label loop;
> 
> Please try if aligning the loop entry improves performance. I'd insert `__ align(32);` here.

This is not improving performance @TheRealMDoerr

> src/hotspot/cpu/ppc/stubGenerator_ppc.cpp line 658:
> 
>> 656:   __ bind(loop);
>> 657:     __ vspltisb(vZero, 0);
>> 658:     __ li(temp1, 0);
> 
> I don't think these instructions should be inside of the loop.

vspltisb(vZero,0) is needed. 
    __ vsldoi(vTmp8, vTmp5, vZero, 8);          // mL : Extract the lower 64 bits of M
    __ vsldoi(vTmp9, vZero, vTmp5, 8);          // mH : Extract the higher 64 bits of M
    We need to extract appropriate bits and for that vZero needs to be initialised to 0 always.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20235#discussion_r1946858131
PR Review Comment: https://git.openjdk.org/jdk/pull/20235#discussion_r1946859665