if (shift > 2 || shift < 0) && (isADDop(p.As) || isADDWop(p.As) || isNEGop(p.As)) {
			c.ctxt.Diag("unsupported shift operator: %v", p)
		}
		o1 |= uint32(p.From.Offset) /* includes reg, op, etc */
		rt := int(p.To.Reg)
		if p.To.Type == obj.TYPE_NONE {
			rt = REGZERO
		}
		r := int(p.Reg)
		if p.As == AMVN || p.As == AMVNW || isNEGop(p.As) {
			r = REGZERO
		} else if r == obj.REG_NONE {
			r = rt