RFR: JDK-8216437 : PPC64: Add intrinsic for GHASH algorithm [v31]

[Andrew Haley]

On Thu, 24 Apr 2025 14:13:50 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:
> 
>   masm

Please run AESGCMByteBuffer.encrypt and provide some before and after figures.

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PR Comment: https://git.openjdk.org/jdk/pull/20235#issuecomment-2827844821