[llvm-branch-commits] [llvm] AMDGPU: Reduce 64-bit add width if low bits are known 0 (PR #122049)

[Matt Arsenault via llvm-branch-commits]

arsenm wrote:

### Merge activity

* **Jan 8, 10:24 AM EST**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/122049).


https://github.com/llvm/llvm-project/pull/122049