[Bug middle-end/93806] Wrong optimization: instability of floating-point results with -funsafe-math-optimizations leads to nonsense

[vincent-gcc at vinc17 dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93806

--- Comment #37 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
(In reply to rguenther@suse.de from comment #36)
> We're actually careful about the sign of zero here when recording
> requivalences for propagation.

But shouldn't the use of -fno-signed-zeros imply that the sign of zero never
matches (i.e. the actual sign is unknown, because unsafe optimizations could
have modified it in an inconsistent way)?