RFR: JDK-8216437 : PPC64: Add intrinsic for GHASH algorithm [v22]

[Martin Doerr]

On Tue, 11 Feb 2025 07:15:27 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 two additional commits since the last revision:
> 
>  - common code function
>  - common code function

src/hotspot/cpu/ppc/stubGenerator_ppc.cpp line 571:

> 569:     masm->vxor(vTmp10, vTmp10, vTmp6);     // Combine reduced Low & High products
> 570:     masm->vxor(vState, vTmp4, vTmp10);
> 571:     masm->addi(data, data, 16);

I think incrementing the data pointer fits better into the loop instead of this helper function.
Don't forget that hotspot uses 2 spaces indentation!

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PR Review Comment: https://git.openjdk.org/jdk/pull/20235#discussion_r1952418392