RFR: 8349582: APX NDD code generation for OpenJDK [v12]

[Srinivas Vamsi Parasa]

> The goal of this PR is to generate x86 code using Intel Advanced Performance Extensions (APX) instructions which doubles the number of general-purpose registers, from 16 to 32. Intel APX adds nondestructive destination (NDD) and no flags (NF) flavor for the scalar instructions through EVEX encoding.
> 
> For more information about APX, see https://www.intel.com/content/www/us/en/developer/articles/technical/advanced-performance-extensions-apx.html.

Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:

  undo changes to testing implementation

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/23501/files
  - new: https://git.openjdk.org/jdk/pull/23501/files/126dd779..51d0e0d4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23501&range=11
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23501&range=10-11

  Stats: 1381 lines in 2 files changed: 198 ins; 213 del; 970 mod
  Patch: https://git.openjdk.org/jdk/pull/23501.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23501/head:pull/23501

PR: https://git.openjdk.org/jdk/pull/23501