register["R18_PLATFORM"] = register["R18"]
	delete(register, "R18")
	for i := arm64.REG_F0; i <= arm64.REG_F31; i++ {
		register[obj.Rconv(i)] = int16(i)
	}
	for i := arm64.REG_V0; i <= arm64.REG_V31; i++ {
		register[obj.Rconv(i)] = int16(i)
	}

	// System registers.
	for i := 0; i < len(arm64.SystemReg); i++ {
		register[arm64.SystemReg[i].Name] = arm64.SystemReg[i].Reg
	}

				a.Reg = arm64.REG_SXTX + Rnum
			}
		case "LSL":
			a.Index = arm64.REG_LSL + Rnum
		default:
			return errors.New("unsupported general register extension type: " + ext)

		}
	} else if reg <= arm64.REG_V31 && reg >= arm64.REG_V0 {
		switch ext {
		case "B8":
			if isIndex {
				return errors.New("invalid register extension")
			}
			a.Reg = arm64.REG_ARNG + (reg & 31) + ((arm64.ARNG_8B & 15) << 5)
		case "B16":