https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89501
--- Comment #3 from Jeffrey A. Law <law at redhat dot com> --- Yup. It's the same as 18501. We meet UNDEFINED and [0,0] resulting in [0,0] and nothing ever causes reevaluation of the PHI. Things are working as "expected". My approach from 2005 would almost certainly address this instance since we'd see the uninitialized use in the early uninit pass, and later see it went away. It'd ultimately generate indicating there was an uninitialized use of "ret" that was optimized away. But I'm not inclined to rip the scabs of those old wounds and reopen that discussion (for the umpteenth time)
