[llvm] [SimplifyCFG] Rebuild loop headers to account for stale changes (PR #155093)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

Can you please clarify which transform(s) end up invalidating the loop headers? Is it possible to incrementally update them? Or at least do more targeted invalidation?

https://github.com/llvm/llvm-project/pull/155093