case loong64.LSX:
			arng_type, ok = loong64LsxArngExtMap[ext]
			if !ok {
				return errors.New("Loong64 extension: invalid LSX arrangement type: " + ext)
			}

		case loong64.LASX:
			arng_type, ok = loong64LasxArngExtMap[ext]
			if !ok {
				return errors.New("Loong64 extension: invalid LASX arrangement type: " + ext)
			}
		}

		a.Reg = loong64.REG_ARNG
		a.Reg += ((reg & loong64.EXT_REG_MASK) << loong64.EXT_REG_SHIFT)