RFR: 8370196: C2: Improve (U)MulHiLNode::MulHiValue [v6]

[Zihao Lin]

> If nodes both are constant, support constant folding.

Zihao Lin has updated the pull request incrementally with one additional commit since the last revision:

  Fix

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/28097/files
  - new: https://git.openjdk.org/jdk/pull/28097/files/db57746d..053966a1

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28097&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28097&range=04-05

  Stats: 138 lines in 4 files changed: 110 ins; 13 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/28097.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28097/head:pull/28097

PR: https://git.openjdk.org/jdk/pull/28097