[llvm] [CodeGen] Use shared RegClassInfo in basic, greedy and fast allocators (PR #226523)

[Nikhil Kotikalapudi via llvm-commits]

https://github.com/nkotikal commented:

Thanks for the ping. I would like to migrate all four RAs to the shared analysis including PBQP simultaneously rather than just 3 for this PR. I do have some PBQP work in the other PR but it probably makes sense to put the shared analysis here for that one too (the PBQP work on #222450 isn't even in the state we want anyway). 

I'll take a closer look at the diff when I have more time tomorrow, but it makes sense so far. 

https://github.com/llvm/llvm-project/pull/226523