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

[Dmitry Mikushin via llvm-commits]

dmikushin wrote:

@jrbyrnes , since SGPR spills to VGPR, the value of 32 makes sense, as well as 64 for wave64. But why the max value of ExcessVGPRWeight is 2048?

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