[llvm] [DFAJumpThreading] Avoid exploring the paths that never come back (PR #85505)

[Nikita Popov via llvm-commits]

nikic wrote:

Okay, I think I missed a key piece here: https://github.com/llvm/llvm-project/blob/156ab4d4fb06be93b0cfce675e4cf86d330d879c/llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp#L1313-L1317

We only allow one DFA jump thread per invocation of the pass. If that's the case, then not preserving loop info is indeed okay. I'd update that comment though to say that we'd have to handle LoopInfo invalidation if we wanted to change that.

https://github.com/llvm/llvm-project/pull/85505