RFR: 8349582: APX NDD code generation for OpenJDK [v14]

[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:

  add comments for encoding and UCF

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23501/files
  - new: https://git.openjdk.org/jdk/pull/23501/files/a12598b1..e9369a40

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23501&range=13
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23501&range=12-13

  Stats: 3 lines in 2 files changed: 3 ins; 0 del; 0 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