[llvm] [AMDGPU] Prefer lower total register usage in regions with spilling (PR #71882)

[Jeffrey Byrnes via llvm-commits]

jrbyrnes wrote:

This work now builds on top of another patch "Improve ExcessRP flagging". That patch alone has functional changes to the scheduler so I will begin to work on putting out a PR for that work, unless there is reason to not do so. 



https://github.com/llvm/llvm-project/pull/71882