[llvm] [MachineSink] Extend loop sinking capability (PR #117247)

[Philip Reames via llvm-commits]

preames wrote:

@jrbyrnes - Can I ask your plans here?  I've seen cases where something like this would be useful for the RISCV backend.  Are you going to move this towards a per backend enable?  Aside from https://github.com/llvm/llvm-project/pull/127133, are you otherwise happy with the heuristics here?

https://github.com/llvm/llvm-project/pull/117247