[llvm] [CodeGen] Use BasicBlock numbers to map to MBBs (PR #101883)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM

There seems to be a mix of assign and resize uses -- I'd normalize to one or the other. (Unless I'm missing something and the assigns can actually overwrite something?)

https://github.com/llvm/llvm-project/pull/101883