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

[Jatin Bhateja]

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

-------------

Commit messages:
 - 8290322: Optimize Vector.rearrange over byte vectors for AVX512BW targets.

Changes: https://git.openjdk.org/jdk/pull/9498/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9498&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8290322
  Stats: 197 lines in 4 files changed: 193 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/9498.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9498/head:pull/9498

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