Optimization bug with floating-point?

[Steve Kargl]

On Tue, Mar 12, 2019 at 07:45:41PM -0700, Steve Kargl wrote:
> 
> gcc8 --version
> gcc8 (FreeBSD Ports Collection) 8.3.0
> 
> gcc8 -fno-builtin -o z a.c -lm && ./z
> gcc8 -O -fno-builtin -o z a.c -lm && ./z
> gcc8 -O2 -fno-builtin -o z a.c -lm && ./z
> gcc8 -O3 -fno-builtin -o z a.c -lm && ./z
> 
> Max ULP: 2.297073
> Count: 0           (# of ULP that exceed 21)
> 

clang agrees with gcc8 if one changes ...

> int
> main(void)
> {
>    double re, im, u, ur, ui;
>    float complex f;
>    float x, y;

this line to "volatile float x, y".

-- 
Steve