isunordered
#define isunordered(x, y) __builtin_isunordered((x), (y))
#define isunordered(x, y) (isnan(x) || isnan(y))
#undef isunordered
#define isunordered(x, y) __builtin_isunordered(x, y)
#undef isunordered
#define isunordered(x, y) ((x) __builtin_isunordered(y))