https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92936
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- In full generality it would require inspecting all possible program paths (and then decide which ones are "impossible" to take). We're not doing that. Still we should have n = [3, 5] and yes, no info for p (just walking defs isn't appropriate and too simple, consider a p += i; inbetween)
