RFR: 8327794: RISC-V: enable extension features based on impid (Rivos specific change) [v2]

[Hamlin Li]

> Hi,
> Can you review the patch? it enables extension features based on impid.
> Thanks!

Hamlin Li 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 two additional commits since the last revision:

 - Merge branch 'master' into march-mimp-ids
 - Initial commit

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18191/files
  - new: https://git.openjdk.org/jdk/pull/18191/files/b455de44..471a0718

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18191&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18191&range=00-01

  Stats: 94074 lines in 1996 files changed: 12858 ins; 75441 del; 5775 mod
  Patch: https://git.openjdk.org/jdk/pull/18191.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18191/head:pull/18191

PR: https://git.openjdk.org/jdk/pull/18191