[Bug middle-end/84996] Adding or substracting 0.0 could be optimized away even without -ffast-math

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84996

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Iirc it can't due to signaling nans.