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

[Patrick Simmons via llvm-commits]

linuxrocks123 wrote:

@jayfoad yes all I've been doing is keeping this up-to-date with master.  I think the right way to do this is to force this analysis to be preserved except when explicitly invalidated by a pass, but I am not sure how to do that.  If you or @arsenm happen to know what hook makes that happen off the top of your head, that may save me some research time.

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