RFR: 8290322: Optimize Vector.rearrange over byte vectors for AVX512BW targets.

[Joshua Zhu]

On Thu, 14 Jul 2022 18:23:51 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

> Hi All,
> 
> Currently re-arrange over 512bit bytevector is optimized for targets supporting AVX512_VBMI feature, this patch generates efficient JIT sequence to handle it for AVX512BW targets.  Following performance results with newly added benchmark shows
> significant speedup.
> 
> System:  Intel(R) Xeon(R) Platinum 8280 CPU @ 2.70GHz (CascadeLake 28C 2S)
> 
> 
> Baseline:
> =========
> Benchmark                                     (size)   Mode  Cnt      Score   Error   Units
> RearrangeBytesBenchmark.testRearrangeBytes16     512  thrpt    2  16350.330          ops/ms
> RearrangeBytesBenchmark.testRearrangeBytes32     512  thrpt    2  15991.346          ops/ms
> RearrangeBytesBenchmark.testRearrangeBytes64     512  thrpt    2     34.423          ops/ms
> RearrangeBytesBenchmark.testRearrangeBytes8      512  thrpt    2  10873.348          ops/ms
> 
> 
> With-opt:
> =========
> Benchmark                                     (size)   Mode  Cnt      Score   Error   Units
> RearrangeBytesBenchmark.testRearrangeBytes16     512  thrpt    2  16062.624          ops/ms
> RearrangeBytesBenchmark.testRearrangeBytes32     512  thrpt    2  16028.494          ops/ms
> RearrangeBytesBenchmark.testRearrangeBytes64     512  thrpt    2   8741.901          ops/ms
> RearrangeBytesBenchmark.testRearrangeBytes8      512  thrpt    2  10983.226          ops/ms
> 
> 
> Kindly review and share your feedback.
> 
> Best Regards,
> Jatin

Looks good to me. My Cascade Lake server benefits from this change.

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PR: https://git.openjdk.org/jdk/pull/9498