RFR: JDK-8216437 : PPC64: Add intrinsic for GHASH algorithm

[Amit Kumar]

On Thu, 18 Jul 2024 14:31:57 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.

src/hotspot/cpu/ppc/vm_version_ppc.cpp line 309:

> 307:   }
> 308: 
> 309:   if (FLAG_IS_DEFAULT(UseGHASHIntrinsics)) {

Just a passing comment: I guess there should be a check about whether underlying architecture supports vector instruction or not. If it does then only enable intrinsic.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20235#discussion_r1890514646