[llvm-branch-commits] [llvm] AMDGPU: Delete spills of undef values (PR #119684)

[Matt Arsenault via llvm-branch-commits]

arsenm wrote:

> Currently, regalloc won't do subreg spilling. But it will be fixed in the foreseeable future. What will happen if you write a test that spills the `undef` subreg of a tuple? Do you want to cover it anyway?

There's no change in interpretation of an undef use with subregisters. The register is just unused, it doesn't matter what the subregister index is.

https://github.com/llvm/llvm-project/pull/119684