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

[Dmitry Mikushin via llvm-commits]

dmikushin wrote:

@jrbyrnes , is it possible to make the patch to choose the default value of `ExcessVGPRWeight` such that the original behavior of unpatched code could be preserved? It should initially minimize unexpected effects in the high-level code and the chance of this code being blamed. Then, you could tune the parameter in a separate update.

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