RFR: 8352248: Check if CMoveX is supported [v2]

[Hamlin Li]

> Hi,
> Can you help to review this patch?
> 
> Currenlty, seems CMoveX are fully supported on most platforms, except of riscv64.
> On riscv64, there is no efficient way to implement CMoveF/D as other CMoveX (e.g. CMoveI), but it will still bring benefit by just supporting CMoveX without CMoveF/D. This patch is to supply such option.
> 
> As other platforms already supported CMoveX, this patch should not impact them, as `!CMoveNode::supported(_igvn.type(phi))` should always be false.
> 
> BTW, in a subsequent pr for riscv, I'll implement CMoveX except of CMoveF/D, and also return false for CMoveF/D in Matcher::match_rule_supported.
> 
> Thanks!

Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:

  minor

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24095/files
  - new: https://git.openjdk.org/jdk/pull/24095/files/6cfbe221..5a92aa07

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24095&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24095&range=00-01

  Stats: 6 lines in 1 file changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/24095.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24095/head:pull/24095

PR: https://git.openjdk.org/jdk/pull/24095