https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71034
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- I think this is the optimizations that should be done: abs(x) < 0 -> x != x abs(x) >= 0 -> x u== x abs(x) == 0 -> x == 0 abs(x) <= 0 -> x == 0 (since this is an ordered comparison) abs(x) u< 0 -> false abs(x) u>= 0 -> false abs(x) u== 0 -> x == 0 I Hope I did not mess this up and got the unordered comparisons correct.