// Create maps for easy lookup of instruction names etc.
	// Note that there is no list of names as there is for 386 and amd64.
	register[obj.Rconv(arm64.REGSP)] = int16(arm64.REGSP)
	for i := arm64.REG_R0; i <= arm64.REG_R31; i++ {
		register[obj.Rconv(i)] = int16(i)
	}
	// Rename R18 to R18_PLATFORM to avoid accidental use.
	register["R18_PLATFORM"] = register["R18"]
	delete(register, "R18")

// ARM64RegisterShift constructs an ARM64 register with shift operation.
func ARM64RegisterShift(reg, op, count int16) (int64, error) {
	// the base register of shift operations must be general register.
	if reg > arm64.REG_R31 || reg < arm64.REG_R0 {
		return 0, errors.New("invalid register for shift operation")
	}
	return int64(reg&31)<<16 | int64(op)<<22 | int64(uint16(count)), nil
}