RFR: JDK-8216437 : PPC64: Add intrinsic for GHASH algorithm [v29]

[Amit Kumar]

On Wed, 19 Mar 2025 08:26:55 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 three additional commits since the last revision:
> 
>  - comments
>  - comments
>  -  comments

Just a minor tweak, other than this it looks good to me.

src/hotspot/cpu/ppc/stubGenerator_ppc.cpp line 556:

> 554:   // The multiplication results are reduced using `vConstC2` to stay within GF(2^128).
> 555:   // The final computed value is stored back into `vState`.
> 556:   static void computeGCMProduct(MacroAssembler* masm,

Suggestion:

  static void computeGCMProduct(MacroAssembler* _masm,


This way you don't have to use `masm->` in this method, you can just use `__` as usual.

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Marked as reviewed by amitkumar (Committer).

PR Review: https://git.openjdk.org/jdk/pull/20235#pullrequestreview-2789506275
PR Review Comment: https://git.openjdk.org/jdk/pull/20235#discussion_r2057430605