https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67089
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Created attachment 36830 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36830&action=edit gcc6-pr67089.patch Untested patch for matching hand written unsigned addition/subtraction overflow checks as {ADD,SUB}_OVERFLOW if target has u{add,sub}v4 optabs.
