[jdk17u-dev] RFR: 8290322: Optimize Vector.rearrange over byte vectors for AVX512BW targets. [v3]

[Jatin Bhateja]

> Clean backport of [JDK-8290322](https://bugs.openjdk.org/browse/JDK-8290322), due to merge conflicts original patch could not be applied directly by bot.
> 
> Patch enables wide vector byte level permutation for AVX512BW targets and benefits multiple generations of Intel's Xeon servers (SKX, CLX, CPX) prior to Ice lake which provides a direct HW instruction (VPERMB). JIT instruction sequence emitted in this case is specific to Vector.rearrange API, hence the scope of the patch is limited to VectorAPIs which is an incubating module currently.
> 
> Vector API jtreg test suite contains multiple tests cases for ByteVector.SPECIES_512 to extensively tests the patch.
> 
> Original patch review was done with [PR 9498](https://github.com/openjdk/jdk/pull/9498)

Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:

  Backport 38a81913d33c856d64b7c26f934026815a482e43

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

Changes:
  - all: https://git.openjdk.org/jdk17u-dev/pull/917/files
  - new: https://git.openjdk.org/jdk17u-dev/pull/917/files/697699eb..ac9e9db9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=917&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=917&range=01-02

  Stats: 93 lines in 2 files changed: 47 ins; 46 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/917.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev pull/917/head:pull/917

PR: https://git.openjdk.org/jdk17u-dev/pull/917