[llvm] [SimplifyCFG] Fix hoisting problem in SimplifyCFG (PR #78615)

[Quentin Dian via llvm-commits]

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

Thanks. LGTM. Even though the code here has become more complex, I didn't find any significant problems.
I'll merge in the following days. That way, others may have time to come and review it.

BTW, when I have time, I'll try to simplify the code here.

https://github.com/llvm/llvm-project/pull/78615