[llvm-branch-commits] [llvm] release/18.x: [SystemZ] Fix overflow flag for i128 USUBO (PR #86491)

[Ulrich Weigand via llvm-branch-commits]

uweigand wrote:

> Hi @uweigand (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix.

This fix is for a regression that only came in with LLVM 18 due to the rework of i128 support (which is already called out in the LLVM 18 release notes).  So I don't think there's really any strong need to add another release note.  If we did want to call this out specifically, I'd say something like:
- Fix a `llvm.usub.with.overflow.i128` wrong code generation regression that was introduced with LLVM 18.1.0.


https://github.com/llvm/llvm-project/pull/86491