[llvm] [CodeGen] Add MachineRegisterClassInfo analysis pass (PR #164877)

[Jay Foad via llvm-commits]

jayfoad wrote:

For AMDGPU it still seems like we are running the analysis too many times. I would expect one initial run plus maybe another one after the wwm alloc pass. Most other passes should preserve this.

https://github.com/llvm/llvm-project/pull/164877