Compares the lower double-precision, floating-point value of a and b for a equal to b.
int _mm_comieq_sd (__m128d a, __m128d b); COMISD
If a and b are equal, 1 is returned. Otherwise, 0 is returned. If a and b is a NaN, 1 is returned.
r := (a0 == b0) ? 0x1 : 0x0
END Microsoft Specific