[Bug middle-end/88575] gcc got confused by different comparison operators

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88575

--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
On Sat, 22 Dec 2018, bugzilla@poradnik-webmastera.com wrote:

> In test() gcc is not able to determine that for a==b it does not have to
> evaluate 2nd comparison and can use value of a if 1st comparison is true. When
> operators are swapped like in test2() or are the same, code is optimized.
> 
> [code]
> double test(double a, double b)
> {
>     if (a <= b)
>         return a < b ? a : b;
>     return 0.0;
> }

You didn't give compilation options, but if a and b are +0 and -0 in some 
order, the first comparison is true but b must be returned instead of a 
(in the absence of -fno-signed-zeros or an option implying it).