[jdk26] RFR: 8375653: C2: CmpUNode::sub is not monotonic [v2]

[Quan Anh Mai]

> Hi all,
> 
> This pull request contains a backport of commit [30675faa](https://github.com/openjdk/jdk/commit/30675faa67d1bbb4acc729a841493bb8311416af) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.
> 
> The commit being backported was authored by Quan Anh Mai on 26 Jan 2026 and was reviewed by Christian Hagedorn and Marc Chevalier.
> 
> Thanks!

Quan Anh Mai has updated the pull request incrementally with one additional commit since the last revision:

  Fix test

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/29412/files
  - new: https://git.openjdk.org/jdk/pull/29412/files/806a2feb..40fc3ff2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29412&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29412&range=00-01

  Stats: 8 lines in 1 file changed: 0 ins; 2 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/29412.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29412/head:pull/29412

PR: https://git.openjdk.org/jdk/pull/29412