[llvm] [SimplifyCFG] Simplify conditional branches on const icmp eq's (PR #73334)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

What is the broader motivation for this? That is, why is it important to handle this within a single SimplifyCFG invocation? We'd probably want to have a PhaseOrdering test for that.

I'm not entirely sure whether this is the best approach. A possible alternative would be to instead perform additional simplification when removing the unreachable block and simplifying the phi to a constant. We could try to simplify all instructions that used the phi at that point.

https://github.com/llvm/llvm-project/pull/73334