[jdk17] RFR: 8269825: [TESTBUG] Missing testing for x86 KNL platforms [v2]

[Vladimir Kozlov]

> Knights family of X86 Intel CPU (KNL) does not support some of avx512 features (AVX512VL/BW) and have other restrictions. We may not have such kind of machines in our testing environment and may miss bugs as JBS history shows (look recent fixes for KNL).
> On other hand we have some Windows VM instances which seem emulate KNL configuration and limit avx512 instructions on CPU which supports full set. Recent bug JDK-8269775 shows such example.
> I suggest to add -XX:+UseKNLSetting x86 diagnostic flag to emulate KNL settings in HotSpot VM to test such configuration.

Vladimir Kozlov has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Exclude more CPU features to emulate KNL cpu
 - Merge branch 'master' into JDK-8269825
 - 8269825: [TESTBUG] Missing testing for x86 KNL platforms

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

Changes:
  - all: https://git.openjdk.java.net/jdk17/pull/205/files
  - new: https://git.openjdk.java.net/jdk17/pull/205/files/9466fb97..4117946a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk17&pr=205&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk17&pr=205&range=00-01

  Stats: 3695 lines in 52 files changed: 2834 ins; 359 del; 502 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/205.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/205/head:pull/205

PR: https://git.openjdk.java.net/jdk17/pull/205