[llvm] [SimplifyCFG] Hoist out implied conditions from successor (PR #158773)

[Nikita Popov via llvm-commits]

https://github.com/nikic requested changes to this pull request.

It looks like currently you are just looking for any icmp inside the block and hoisting it. This is not correct: It needs to be connected to the control flow in a specific way. Hoisting the condition means that the branch is executed in fewer cases, and you need to make sure that's fine.

(As a trivial counter example, consider the case where the block just contains a completely unused icmp.)

https://github.com/llvm/llvm-project/pull/158773