r = REGZERO
		} else if r == obj.REG_NONE {
			r = rt
		}
		o1 |= (uint32(r&31) << 5) | uint32(rt&31)

	case 4: /* mov $addcon, R; mov $recon, R; mov $racon, R; mov $addcon2, R */
		rt, r := p.To.Reg, o.param
		if r == obj.REG_NONE {
			r = REGZERO
		} else if r == REGFROM {
			r = p.From.Reg
		}
		if r == obj.REG_NONE {
			r = REGSP
		}