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

[Nikita Popov via llvm-commits]

nikic wrote:

> Can you please add something like `if (VerifyLoopInfo) LI->verify(DT)` and add `-verify-loop-info` to all the DFAJumpThreading tests? Can also mark the analysis as preserved.

Or maybe better, just add the verify call to https://github.com/llvm/llvm-project/blob/dbbdee2ea2156170062813fb3d7f2c023d65e02d/llvm/lib/Transforms/Scalar/DFAJumpThreading.cpp#L1312 and then run it locally once with EXPENSIVE_CHECKS replaced by 1.

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