if err != nil {
			p.errorf("parsing element index: %s", err)
		}
		isIndex = true
		isAmount = false
		num = int16(index)
	}

	switch p.arch.Family {
	case sys.ARM64:
		err := arm64.EncodeRegisterExtension(a, ext, reg, num, isAmount, isIndex)
		if err != nil {
			p.errorf("%v", err)
		}
	case sys.Loong64:
		err := arch.Loong64RegisterExtension(a, ext, reg, num, isAmount, isIndex)
		if err != nil {