https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64130
--- Comment #6 from Marc Glisse <glisse at gcc dot gnu.org> --- (In reply to kugan from comment #5) > I think it should be in from front-end? ? > Tried fixing it in VRP like: You don't seem to use ranges at all. This might be the right place to implement the suggestion from comment #2 (though if it does not use ranges, match.pd would be better), but for the original optimization, what you want to improve is the computation of the range of a division. When a has range [0, 4294967295] we compute for 2305843009213693951 / a the range [0, 2305843009213693951] which is not optimal, the left bound should be 536870912 not 0. If the good interval is computed, VRP will automatically fold == 0 to false without extra code. We already get this right when a has range [1, 4294967295].
