RFR: 8329254: optimize integral reverse operations on x86 GFNI target. [v2]

[Sandhya Viswanathan]

On Wed, 10 Apr 2024 19:01:35 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> - Efficient GFNI based instruction sequence to compute integral reverse operation was added along with JEP-426 (VectorAPI 4th Incubation). https://bugs.openjdk.org/browse/JDK-8284960
>> 
>> - However, the CPUID based feature detection for GFNI was incorrectly performed under AVX512 check, fixing it shows roughly 2X performance improvement for Integer/Long.reverse APIs on E-core targets (MTL+).
>> 
>> 
>> BaseLine:
>> Benchmark              (size)  Mode  Cnt  Score   Error  Units
>> Integers.reverse          500  avgt    2  0.120          us/op
>> Longs.reverse             500  avgt    2  0.221          us/op
>> 
>> Withopt:
>> Benchmark              (size)  Mode  Cnt  Score   Error  Units
>> Integers.reverse          500  avgt    2  0.050          us/op
>> Longs.reverse             500  avgt    2  0.086          us/op
>> 
>> 
>> Kindly review.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Review comment resolution.

Looks good to me.

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Marked as reviewed by sviswanathan (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18530#pullrequestreview-1992595041