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

[Nikita Popov via llvm-commits]

nikic wrote:

My general concern with not preserving LoopInfo is that we still continue using LoopInfo even after it has been invalidated. Let's say we have two candidates for DFA jump threading in a function. When we process the first one, we modify the CFG without (fully) updating LoopInfo. Then for the second one, we query LoopInfo -- but the LoopInfo is broken now. Can this cause any issues? I find it hard to tell...

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