[Bug tree-optimization/56286] vectorizer does not keep loop-closed SSA up-to-date

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56286

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Note the ??? is now moved to tree-vectorizer.c:

  if (num_vectorized_loops > 0)
    {
      /* If we vectorized any loop only virtual SSA form needs to be updated.
         ???  Also while we try hard to update loop-closed SSA form we fail
         to properly do this in some corner-cases (see PR56286).  */
      rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa_only_virtuals);
      return TODO_cleanup_cfg;