fmt.Fprintf(os.Stderr, "Flags:\n")
	flag.PrintDefaults()
	os.Exit(2)
}

func Parse() {
	objabi.Flagparse(Usage)
	if flag.NArg() == 0 {
		flag.Usage()
	}

	// Flag refinement.
	if *OutputFile == "" {
		if flag.NArg() != 1 {
			flag.Usage()
		}
		input := filepath.Base(flag.Arg(0))
		input = strings.TrimSuffix(input, ".s")
		*OutputFile = fmt.Sprintf("%s.o", input)
	}