[llvm] [SimplifyCFG] Avoid branch threading of divergent conditionals (PR #141867)

[Nikita Popov via llvm-commits]

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

We definitely cannot use UniformityInfo inside SimplifyCFG as things are right now. And we will most likely *never* be able to use it in SimplifyCFG and JumpThreading -- passes which perform CFG modifications so invasive, that just keeping an up-to-date dominator tree, let alone a complex derived analysis, is a non-starter.

https://github.com/llvm/llvm-project/pull/141867