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

[Martin Doerr]

On Wed, 5 Feb 2025 08:38:58 GMT, Suchismith Roy <sroy at openjdk.org> wrote:

>> JBS Issue : [JDK-8216437](https://bugs.openjdk.org/browse/JDK-8216437)
>> 
>> Currently acceleration code for GHASH is missing for PPC64. 
>> 
>> The current implementation utlilises SIMD instructions on Power and uses Karatsuba multiplication for obtaining the final result.
>
> 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 658:

> 656:   __ bind(loop);
> 657:     __ vspltisb(vZero, 0);
> 658:     __ li(temp1, 0);

I don't think these instructions should be inside of the loop.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20235#discussion_r1945125696