https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90248
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Yeah, all those look quite questionable, -fno-signed-zeros doesn't mean 0.0 or -0.0 won't appear, just that it shouldn't matter if 0.0 or -0.0 appears. So the > 0.0 and <= 0.0 cases look completely bogus and the rest too, >= 0.0 or < 0.0 works regardless of what sign the zero has, while if copysign is used, then it is significant, and not just in the sign of some zero, but actually whether the result is -1.0 or 1.0.
