Re: signalling NaNs on i386 and x86_64

[Paul Eggert]

On 2023-10-16 16:09, Bruno Haible wrote:
> In my tests so far, they seem to be reliable except on x86 and sh4 CPUs. 
> (For sh4, because of a gcc bug.)

I am partly relying on the GCC manual which contains the delicious 
sentence "This option is experimental and does not currently guarantee 
to disable all GCC optimizations that affect signaling NaN behavior."[1]

I translate this to "If you compile with -fsignaling-nans you should get 
behavior that works for signaling NaNs, but this area is buggy so don't 
count on it (and anyway why are you wasting your precious time worrying 
about signaling NaNs?)." (Admittedly the parenthesized part is my 
editorializing. :-)

[1]: 
<https://gcc.gnu.org/onlinedocs/gcc-13.2.0/gcc/Optimize-Options.html#index-fsignaling-nans>