extern void abort (void);

double
__attribute__ ((noinline))
not_fabs (double x)
{
  return x >= 0.0 ? x : -x;
}

int main()
{
  double x = -0.0;
  double y;

  y = not_fabs (x);

  if (!__builtin_signbit (y))
    abort();

  return 0;
}