return 0, errors.New("invalid register for shift operation")
	}
	return int64(reg&31)<<16 | int64(op)<<22 | int64(uint16(count)), nil
}

// ARM64RegisterArrangement constructs an ARM64 vector register arrangement.
func ARM64RegisterArrangement(reg int16, name, arng string) (int64, error) {
	var curQ, curSize uint16
	if name[0] != 'V' {
		return 0, errors.New("expect V0 through V31; found: " + name)
	}

			if !ok {
				p.errorf("invalid register: %s", name)
			}
			reg := r - p.arch.Register["V0"]
			p.get('.')
			tok := p.next()
			ext := tok.String()
			curArrangement, err := arch.ARM64RegisterArrangement(reg, name, ext)
			if err != nil {
				p.errorf("%v", err)
			}
			if firstReg == -1 {
				// only record the first register and arrangement
				firstReg = int(reg)
				nextReg = firstReg