I think the diagram must be slightly incorrect, else there are some odd bits. * 20 is copied into 22 unchanged * 20 = min(min(14, 15), 14) - min(14, 15), which

I think the diagram must be slightly incorrect, else there are some odd bits. * 20 is copied into 22 unchanged * 20 = min(min(14, 15), 14) - min(14, 15), which all simplifies to 0