RFR: JDK-8216437 : PPC64: Add intrinsic for GHASH algorithm [v23]

[Martin Doerr]

On Mon, 17 Feb 2025 14:05:12 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:
> 
>   Single load inside loop

src/hotspot/cpu/ppc/stubGenerator_ppc.cpp line 562:

> 560:                               VectorRegister vTmp4, VectorRegister vTmp5, VectorRegister vTmp6,
> 561:                               VectorRegister vTmp7, VectorRegister vTmp8, VectorRegister vTmp9,
> 562:                               VectorRegister vTmp10, VectorRegister vTmp11, Register data) {

`data` is no longer needed.

src/hotspot/cpu/ppc/stubGenerator_ppc.cpp line 714:

> 712:       __ vec_perm(vTmp5, vLow, vLow, loadOrder);
> 713:       __ vec_perm(vH, vTmp5, vTmp4, vPerm);
> 714:       __ subi(data, data, 16);

sub and add below are no longer needed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20235#discussion_r1959533373
PR Review Comment: https://git.openjdk.org/jdk/pull/20235#discussion_r1959533794