https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118297
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> --- The messages unfortunately cobble up for the different variants of vectorization we try. The 'unsupported outerloop form' is when trying to vectorize the outer loop, for the inner loop the issue is similar: t.C:28:9: missed: not vectorized: could not determine main exit from loop with multiple exits. t.C:28:9: missed: bad loop form. t.C:28:9: missed: couldn't vectorize loop which is because the loop doesn't have a simple incrementing IV, so we can't symbolically compute its number of iterations.
