CommandLine.cpp

    GetOptionInfo(PositionalOpts, SinkOpts, OptMap);

    // Copy Options into a vector so we can sort them as we like...
    std::vector<std::pair<std::string, Option*> > Opts;
    copy(OptMap.begin(), OptMap.end(), std::back_inserter(Opts));

    // Eliminate Hidden or ReallyHidden arguments, depending on ShowHidden
    Opts.erase(std::remove_if(Opts.begin(), Opts.end(),
                          std::ptr_fun(ShowHidden ? isReallyHidden : isHidden)),
               Opts.end());

    // Eliminate duplicate entries in table (from enum flags options, f.e.)
    {  // Give OptionSet a scope
      std::set<Option*> OptionSet;
      for (unsigned i = 0; i != Opts.size(); ++i)
        if (OptionSet.count(Opts[i].second) == 0)
          OptionSet.insert(Opts[i].second);   // Add new entry to set
        else
          Opts.erase(Opts.begin()+i--);    // Erase duplicate
    }

    if (ProgramOverview)
      cout << "OVERVIEW: " << ProgramOverview << "\n";

    cout << "USAGE: " << ProgramName << " [options]";

    // Print out the positional options.
    Option *CAOpt = 0;   // The cl::ConsumeAfter option, if it exists...
    if (!PositionalOpts.empty() &&
        PositionalOpts[0]->getNumOccurrencesFlag() == ConsumeAfter)
      CAOpt = PositionalOpts[0];

    for (size_t i = CAOpt != 0, e = PositionalOpts.size(); i != e; ++i) {
      if (PositionalOpts[i]->ArgStr[0])
        cout << " --" << PositionalOpts[i]->ArgStr;
      cout << " " << PositionalOpts[i]->HelpStr;
    }

    // Print the consume after option info if it exists...
    if (CAOpt) cout << " " << CAOpt->HelpStr;

    cout << "\n\n";

    // Compute the maximum argument length...
    MaxArgLen = 0;
    for (size_t i = 0, e = Opts.size(); i != e; ++i)
      MaxArgLen = std::max(MaxArgLen, Opts[i].second->getOptionWidth());

    cout << "OPTIONS:\n";
    for (size_t i = 0, e = Opts.size(); i != e; ++i)
      Opts[i].second->printOptionInfo(MaxArgLen);

    // Print any extra help the user has declared.
    for (std::vector<const char *>::iterator I = MoreHelp->begin(),
          E = MoreHelp->end(); I != E; ++I)
      cout << *I;
    MoreHelp->clear();

    // Halt the program since help information was printed
    exit(1);
  }
};
} // End anonymous namespace

// Define the two HelpPrinter instances that are used to print out help, or
// help-hidden...
//
static HelpPrinter NormalPrinter(false);
static HelpPrinter HiddenPrinter(true);

static cl::opt<HelpPrinter, true, parser<bool> >
HOp("help", cl::desc("Display available options (--help-hidden for more)"),
    cl::location(NormalPrinter), cl::ValueDisallowed);

static cl::opt<HelpPrinter, true, parser<bool> >
HHOp("help-hidden", cl::desc("Display all available options"),
     cl::location(HiddenPrinter), cl::Hidden, cl::ValueDisallowed);

static void (*OverrideVersionPrinter)() = 0;

namespace {
class VersionPrinter {
public:
  void print() {
        cout << "Low Level Virtual Machine (http://llvm.org/):\n";
        cout << "  " << PACKAGE_NAME << " version " << PACKAGE_VERSION;
#ifdef LLVM_VERSION_INFO
        cout << LLVM_VERSION_INFO;
#endif
        cout << "\n  ";
#ifndef __OPTIMIZE__
        cout << "DEBUG build";
#else
        cout << "Optimized build";
#endif
#ifndef NDEBUG
        cout << " with assertions";
#endif
        cout << ".\n";
  }
  void operator=(bool OptionWasSpecified) {
    if (OptionWasSpecified) {
      if (OverrideVersionPrinter == 0) {
        print();
        exit(1);
      } else {
        (*OverrideVersionPrinter)();
        exit(1);
      }
    }
  }
};
} // End anonymous namespace


// Define the --version option that prints out the LLVM version for the tool
static VersionPrinter VersionPrinterInstance;

static cl::opt<VersionPrinter, true, parser<bool> >
VersOp("version", cl::desc("Display the version of this program"),
    cl::location(VersionPrinterInstance), cl::ValueDisallowed);

// Utility function for printing the help message.
void cl::PrintHelpMessage() {
  // This looks weird, but it actually prints the help message. The
  // NormalPrinter variable is a HelpPrinter and the help gets printed when
  // its operator= is invoked. That's because the "normal" usages of the
  // help printer is to be assigned true/false depending on whether the
  // --help option was given or not. Since we're circumventing that we have
  // to make it look like --help was given, so we assign true.
  NormalPrinter = true;
}

/// Utility function for printing version number.
void cl::PrintVersionMessage() {
  VersionPrinterInstance.print();
}

void cl::SetVersionPrinter(void (*func)()) {
  OverrideVersionPrinter = func;
}