[llvm] [LoopInterchange] Check all inner-exit LCSSA PHIs (PR #200860)

[Ryotaro Kasuga via llvm-commits]

https://github.com/kasuga-fj approved this pull request.

LGTM, but I'd prefer replacing `[100 x [100 x i32]]` with `[100 x i32]`, since the former is simply a bit confusing, I think.

https://github.com/llvm/llvm-project/pull/200860