// so that the reader can tell the size of memory operand.
		// up with the same arguments
		dst, _ := inst.Args[0].(Reg)
		src, _ := inst.Args[1].(Reg)
		if ES <= src && src <= GS && isMem(inst.Args[0]) || ES <= dst && dst <= GS && isMem(inst.Args[1]) {
			unmarkImplicit(&inst, PrefixDataSize)
		}

	case MOVDQU:
		if countPrefix(&inst, 0xF3) > 1 {
			unmarkImplicit(&inst, 0xF3)
			markLastImplicit(&inst, 0xF3)
		}

	}
	return buf.String()
}

func isReg(a Arg) bool {
	_, ok := a.(Reg)
	return ok
}

func isSegReg(a Arg) bool {
	r, ok := a.(Reg)
	return ok && ES <= r && r <= GS
}

func isMem(a Arg) bool {
	_, ok := a.(Mem)
	return ok
}

func isImm(a Arg) bool {
	_, ok := a.(Imm)
	return ok
}

func regBytes(a Arg) int {
	r, ok := a.(Reg)
	if !ok {
		return 0
	}

		switch inst.Op {
		// TODO(rsc): Perhaps this instruction class should be derived from the CSV.
		case ADD, ADC, AND, BTC, BTR, BTS, CMPXCHG, CMPXCHG8B, CMPXCHG16B, DEC, INC, NEG, NOT, OR, SBB, SUB, XOR, XADD, XCHG:
			if isMem(inst.Args[0]) {
				hasLock = true
				break
			}
			fallthrough
		default:
			inst.Prefix[lockIndex] |= PrefixInvalid
		}
	}