sys::Path Tool::OutFilename(const sys::Path& In,
                            const sys::Path& TempDir,
                            bool StopCompilation,
                            const char* OutputSuffix) const {
  sys::Path Out;

  if (StopCompilation) {
    if (!OutputFilename.empty()) {
      Out.set(OutputFilename);
    }
    else if (IsJoin()) {
      Out.set("a");
      Out.appendSuffix(OutputSuffix);
    }
    else {
      Out.set(In.getBasename());
      Out.appendSuffix(OutputSuffix);
    }
  }
  else {
    if (IsJoin())
      Out = MakeTempFile(TempDir, "tmp", OutputSuffix);
    else
      Out = MakeTempFile(TempDir, In.getBasename(), OutputSuffix);
  }
  return Out;
}

// recurseDirectories - Implements the "R" modifier. This function scans through
// the Paths vector (built by buildPaths, below) and replaces any directories it
// finds with all the files in that directory (recursively). It uses the
// sys::Path::getDirectoryContent method to perform the actual directory scans.
bool
recurseDirectories(const sys::Path& path,
                   std::set<sys::Path>& result, std::string* ErrMsg) {
    result.clear();
    if (RecurseDirectories) {
        std::set<sys::Path> content;
        if (path.getDirectoryContents(content, ErrMsg))
            return true;

        for (std::set<sys::Path>::iterator I = content.begin(), E = content.end();
                I != E; ++I) {
            // Make sure it exists and is a directory
            sys::PathWithStatus PwS(*I);
            const sys::FileStatus *Status = PwS.getFileStatus(false, ErrMsg);
            if (!Status)
                return true;
            if (Status->isDir) {
                std::set<sys::Path> moreResults;
                if (recurseDirectories(*I, moreResults, ErrMsg))
                    return true;
                result.insert(moreResults.begin(), moreResults.end());
            } else {
                result.insert(*I);
            }
        }
    }
    return false;
}

bool LTOCodeGenerator::assemble(const std::string& asmPath, 
                                const std::string& objPath, std::string& errMsg)
{
    // find compiler driver
    const sys::Path gcc = sys::Program::FindProgramByName("gcc");
    if ( gcc.isEmpty() ) {
        errMsg = "can't locate gcc";
        return true;
    }

    // build argument list
    std::vector<const char*> args;
    std::string targetTriple = _linker.getModule()->getTargetTriple();
    args.push_back(gcc.c_str());
    if ( targetTriple.find("darwin") != targetTriple.size() ) {
        if (strncmp(targetTriple.c_str(), "i686-apple-", 11) == 0) {
            args.push_back("-arch");
            args.push_back("i386");
        }
        else if (strncmp(targetTriple.c_str(), "x86_64-apple-", 13) == 0) {
            args.push_back("-arch");
            args.push_back("x86_64");
        }
        else if (strncmp(targetTriple.c_str(), "powerpc-apple-", 14) == 0) {
            args.push_back("-arch");
            args.push_back("ppc");
        }
        else if (strncmp(targetTriple.c_str(), "powerpc64-apple-", 16) == 0) {
            args.push_back("-arch");
            args.push_back("ppc64");
        }
    }
    args.push_back("-c");
    args.push_back("-x");
    args.push_back("assembler");
    args.push_back("-o");
    args.push_back(objPath.c_str());
    args.push_back(asmPath.c_str());
    args.push_back(0);

    // invoke assembler
    if ( sys::Program::ExecuteAndWait(gcc, &args[0], 0, 0, 0, 0, &errMsg) ) {
        errMsg = "error in assembly";    
        return true;
    }
    return false; // success
}

// Execute the graph viewer. Return true if successful.
static bool LLVM_ATTRIBUTE_UNUSED
ExecGraphViewer(const sys::Path &ExecPath, std::vector<const char*> &args,
                const sys::Path &Filename, bool wait, std::string &ErrMsg) {
  if (wait) {
    if (sys::Program::ExecuteAndWait(ExecPath, &args[0],0,0,0,0,&ErrMsg)) {
      errs() << "Error: " << ErrMsg << "\n";
      return false;
    }
    Filename.eraseFromDisk();
    errs() << " done. \n";
  }
  else {
    sys::Program::ExecuteNoWait(ExecPath, &args[0],0,0,0,&ErrMsg);
    errs() << "Remember to erase graph file: " << Filename.str() << "\n";
  }
  return true;
}

// LoadObject - Read in and parse the bitcode file named by FN and return the
// module it contains (wrapped in an auto_ptr), or auto_ptr<Module>() and set
// Error if an error occurs.
std::auto_ptr<Module>
Linker::LoadObject(const sys::Path &FN) {
  std::string ParseErrorMessage;
  Module *Result = 0;

  OwningPtr<MemoryBuffer> Buffer;
  if (error_code ec = MemoryBuffer::getFileOrSTDIN(FN.c_str(), Buffer))
    ParseErrorMessage = "Error reading file '" + FN.str() + "'" + ": "
                      + ec.message();
  else
    Result = ParseBitcodeFile(Buffer.get(), Context, &ParseErrorMessage);

  if (Result)
    return std::auto_ptr<Module>(Result);
  Error = "Bitcode file '" + FN.str() + "' could not be loaded";
  if (ParseErrorMessage.size())
    Error += ": " + ParseErrorMessage;
  return std::auto_ptr<Module>();
}

// LoadObject - Read in and parse the bitcode file named by FN and return the
// module it contains (wrapped in an auto_ptr), or auto_ptr<Module>() and set
// Error if an error occurs.
std::auto_ptr<Module>
Linker::LoadObject(const sys::Path &FN) {
  std::string ParseErrorMessage;
  Module *Result = 0;
  
  const std::string &FNS = FN.toString();
  std::auto_ptr<MemoryBuffer> Buffer(MemoryBuffer::getFileOrSTDIN(FNS.c_str()));
  if (Buffer.get())
    Result = ParseBitcodeFile(Buffer.get(), &ParseErrorMessage);
  else
    ParseErrorMessage = "Error reading file '" + FNS + "'";
    
  if (Result)
    return std::auto_ptr<Module>(Result);
  Error = "Bitcode file '" + FN.toString() + "' could not be loaded";
  if (ParseErrorMessage.size())
    Error += ": " + ParseErrorMessage;
  return std::auto_ptr<Module>();
}

// Insert a file into the archive before some other member. This also takes care
// of extracting the necessary flags and information from the file.
bool
Archive::addFileBefore(const sys::Path& filePath, iterator where,
                        std::string* ErrMsg) {
  bool Exists;
  if (sys::fs::exists(filePath.str(), Exists) || !Exists) {
    if (ErrMsg)
      *ErrMsg = "Can not add a non-existent file to archive";
    return true;
  }

  ArchiveMember* mbr = new ArchiveMember(this);

  mbr->data = 0;
  mbr->path = filePath;
  const sys::FileStatus *FSInfo = mbr->path.getFileStatus(false, ErrMsg);
  if (!FSInfo) {
    delete mbr;
    return true;
  }
  mbr->info = *FSInfo;

  unsigned flags = 0;
  bool hasSlash = filePath.str().find('/') != std::string::npos;
  if (hasSlash)
    flags |= ArchiveMember::HasPathFlag;
  if (hasSlash || filePath.str().length() > 15)
    flags |= ArchiveMember::HasLongFilenameFlag;

  sys::fs::file_magic type;
  if (sys::fs::identify_magic(mbr->path.str(), type))
    type = sys::fs::file_magic::unknown;
  switch (type) {
    case sys::fs::file_magic::bitcode:
      flags |= ArchiveMember::BitcodeFlag;
      break;
    default:
      break;
  }
  mbr->flags = flags;
  members.insert(where,mbr);
  return false;
}

// Get just the externally visible defined symbols from the bitcode
bool llvm::GetBitcodeSymbols(const sys::Path& fName,
                             LLVMContext& Context,
                             std::vector<std::string>& symbols,
                             std::string* ErrMsg) {
  OwningPtr<MemoryBuffer> Buffer;
  if (error_code ec = MemoryBuffer::getFileOrSTDIN(fName.c_str(), Buffer)) {
    if (ErrMsg) *ErrMsg = "Could not open file '" + fName.str() + "'" + ": "
                        + ec.message();
    return true;
  }

  Module *M = ParseBitcodeFile(Buffer.get(), Context, ErrMsg);
  if (!M)
    return true;

  // Get the symbols
  getSymbols(M, symbols);

  // Done with the module.
  delete M;
  return true;
}

// Insert a file into the archive before some other member. This also takes care
// of extracting the necessary flags and information from the file.
bool
Archive::addFileBefore(const sys::Path& filePath, iterator where, 
                        std::string* ErrMsg) {
  if (!filePath.exists()) {
    if (ErrMsg)
      *ErrMsg = "Can not add a non-existent file to archive";
    return true;
  }

  ArchiveMember* mbr = new ArchiveMember(this);

  mbr->data = 0;
  mbr->path = filePath;
  const sys::FileStatus *FSInfo = mbr->path.getFileStatus(false, ErrMsg);
  if (!FSInfo) {
    delete mbr;
    return true;
  }
  mbr->info = *FSInfo;

  unsigned flags = 0;
  bool hasSlash = filePath.str().find('/') != std::string::npos;
  if (hasSlash)
    flags |= ArchiveMember::HasPathFlag;
  if (hasSlash || filePath.str().length() > 15)
    flags |= ArchiveMember::HasLongFilenameFlag;
  std::string magic;
  mbr->path.getMagicNumber(magic,4);
  switch (sys::IdentifyFileType(magic.c_str(),4)) {
    case sys::Bitcode_FileType:
      flags |= ArchiveMember::BitcodeFlag;
      break;
    default:
      break;
  }
  mbr->flags = flags;
  members.insert(where,mbr);
  return false;
}

/// RunProgramRemotelyWithTimeout - This function runs the given program
/// remotely using the given remote client and the sys::Program::ExecuteAndWait.
/// Returns the remote program exit code or reports a remote client error if it
/// fails. Remote client is required to return 255 if it failed or program exit
/// code otherwise.
/// @see sys::Program::ExecuteAndWait
static int RunProgramRemotelyWithTimeout(const sys::Path &RemoteClientPath,
                                         const char **Args,
                                         const sys::Path &StdInFile,
                                         const sys::Path &StdOutFile,
                                         const sys::Path &StdErrFile,
                                         unsigned NumSeconds = 0,
                                         unsigned MemoryLimit = 0) {
  const sys::Path* redirects[3];
  redirects[0] = &StdInFile;
  redirects[1] = &StdOutFile;
  redirects[2] = &StdErrFile;

#if 0 // For debug purposes
  {
    errs() << "RUN:";
    for (unsigned i = 0; Args[i]; ++i)
      errs() << " " << Args[i];
    errs() << "\n";
  }
#endif

  // Run the program remotely with the remote client
  int ReturnCode = sys::Program::ExecuteAndWait(RemoteClientPath, Args,
                                 0, redirects, NumSeconds, MemoryLimit);

  // Has the remote client fail?
  if (255 == ReturnCode) {
    std::ostringstream OS;
    OS << "\nError running remote client:\n ";
    for (const char **Arg = Args; *Arg; ++Arg)
      OS << " " << *Arg;
    OS << "\n";

    // The error message is in the output file, let's print it out from there.
    std::ifstream ErrorFile(StdOutFile.c_str());
    if (ErrorFile) {
      std::copy(std::istreambuf_iterator<char>(ErrorFile),
                std::istreambuf_iterator<char>(),
                std::ostreambuf_iterator<char>(OS));
      ErrorFile.close();
    }

    errs() << OS.str();
  }

  return ReturnCode;
}

/// GenerateAssembly - generates a native assembly language source file from the
/// specified bytecode file.
///
/// Inputs:
///  InputFilename  - The name of the input bytecode file.
///  OutputFilename - The name of the file to generate.
///  llc            - The pathname to use for LLC.
///  envp           - The environment to use when running LLC.
///
/// Return non-zero value on error.
///
static int GenerateAssembly(const std::string &OutputFilename,
                            const std::string &InputFilename,
                            const sys::Path &llc,
                            std::string &ErrMsg ) {
  // Run LLC to convert the bytecode file into assembly code.
  std::vector<const char*> args;
  args.push_back(llc.c_str());
  args.push_back("-f");
  args.push_back("-o");
  args.push_back(OutputFilename.c_str());
  args.push_back(InputFilename.c_str());
  args.push_back(0);

  if (Verbose) {
    cout << "Generating Assembly With: \n";
    PrintCommand(args);
  }

  return sys::Program::ExecuteAndWait(llc, &args[0], 0, 0, 0, 0, &ErrMsg);
}

/// GenerateCFile - generates a C source file from the specified bitcode file.
static int GenerateCFile(const std::string &OutputFile,
                         const std::string &InputFile,
                         const sys::Path &llc,
                         std::string& ErrMsg) {
  // Run LLC to convert the bitcode file into C.
  std::vector<const char*> args;
  args.push_back(llc.c_str());
  args.push_back("-march=c");
  args.push_back("-o");
  args.push_back(OutputFile.c_str());
  args.push_back(InputFile.c_str());
  args.push_back(0);

  if (Verbose) {
    errs() << "Generating C Source With: \n";
    PrintCommand(args);
  }

  return sys::Program::ExecuteAndWait(llc, &args[0], 0, 0, 0, 0, &ErrMsg);
}

/// GenerateAssembly - generates a native assembly language source file from the
/// specified bitcode file.
///
/// Inputs:
///  InputFilename  - The name of the input bitcode file.
///  OutputFilename - The name of the file to generate.
///  llc            - The pathname to use for LLC.
///  envp           - The environment to use when running LLC.
///
/// Return non-zero value on error.
///
static int GenerateAssembly(const std::string &OutputFilename,
                            const std::string &InputFilename,
                            const sys::Path &llc,
                            std::string &ErrMsg ) {
  // Run LLC to convert the bitcode file into assembly code.
  std::vector<const char*> args;
  args.push_back(llc.c_str());
  // We will use GCC to assemble the program so set the assembly syntax to AT&T,
  // regardless of what the target in the bitcode file is.
  args.push_back("-x86-asm-syntax=att");
  args.push_back("-o");
  args.push_back(OutputFilename.c_str());
  args.push_back(InputFilename.c_str());
  args.push_back(0);

  if (Verbose) {
    errs() << "Generating Assembly With: \n";
    PrintCommand(args);
  }

  return sys::Program::ExecuteAndWait(llc, &args[0], 0, 0, 0, 0, &ErrMsg);
}

void llvm::DisplayGraph(const sys::Path &Filename) {
  std::string ErrMsg;
#if HAVE_GRAPHVIZ
  sys::Path Graphviz(LLVM_PATH_GRAPHVIZ);

  std::vector<const char*> args;
  args.push_back(Graphviz.c_str());
  args.push_back(Filename.c_str());
  args.push_back(0);
  
  cerr << "Running 'Graphviz' program... " << std::flush;
  if (sys::Program::ExecuteAndWait(Graphviz, &args[0],0,0,0,0,&ErrMsg)) {
    cerr << "Error viewing graph: " << ErrMsg << "\n";
  }
#elif (HAVE_GV && HAVE_DOT)
  sys::Path PSFilename = Filename;
  PSFilename.appendSuffix("ps");
  
  sys::Path dot(LLVM_PATH_DOT);

  std::vector<const char*> args;
  args.push_back(dot.c_str());
  args.push_back("-Tps");
  args.push_back("-Nfontname=Courier");
  args.push_back("-Gsize=7.5,10");
  args.push_back(Filename.c_str());
  args.push_back("-o");
  args.push_back(PSFilename.c_str());
  args.push_back(0);
  
  cerr << "Running 'dot' program... " << std::flush;
  if (sys::Program::ExecuteAndWait(dot, &args[0],0,0,0,0,&ErrMsg)) {
    cerr << "Error viewing graph: '" << ErrMsg << "\n";
  } else {
    cerr << " done. \n";

    sys::Path gv(LLVM_PATH_GV);
    args.clear();
    args.push_back(gv.c_str());
    args.push_back(PSFilename.c_str());
    args.push_back(0);
    
    ErrMsg.clear();
    if (sys::Program::ExecuteAndWait(gv, &args[0],0,0,0,0,&ErrMsg)) {
      cerr << "Error viewing graph: " << ErrMsg << "\n";
    }
  }
  PSFilename.eraseFromDisk();
#elif HAVE_DOTTY
  sys::Path dotty(LLVM_PATH_DOTTY);

  std::vector<const char*> args;
  args.push_back(dotty.c_str());
  args.push_back(Filename.c_str());
  args.push_back(0);
  
  cerr << "Running 'dotty' program... " << std::flush;
  if (sys::Program::ExecuteAndWait(dotty, &args[0],0,0,0,0,&ErrMsg)) {
    cerr << "Error viewing graph: " << ErrMsg << "\n";
  } else {
#ifdef __MINGW32__ // Dotty spawns another app and doesn't wait until it returns
    return;
#endif
  }
#endif
  
  Filename.eraseFromDisk();
}

/// LinkInFile - opens a bitcode file and links in all objects which
/// provide symbols that are currently undefined.
///
/// Inputs:
///  File - The pathname of the bitcode file.
///
/// Outputs:
///  ErrorMessage - A C++ string detailing what error occurred, if any.
///
/// Return Value:
///  TRUE  - An error occurred.
///  FALSE - No errors.
///
bool Linker::LinkInFile(const sys::Path &File, bool &is_native) {
  is_native = false;
  
  // Check for a file of name "-", which means "read standard input"
  if (File.toString() == "-") {
    std::auto_ptr<Module> M;
    if (MemoryBuffer *Buffer = MemoryBuffer::getSTDIN()) {
      M.reset(ParseBitcodeFile(Buffer, Context, &Error));
      delete Buffer;
      if (M.get())
        if (!LinkInModule(M.get(), &Error))
          return false;
    } else 
      Error = "standard input is empty";
    return error("Cannot link stdin: " + Error);
  }

  // Make sure we can at least read the file
  if (!File.canRead())
    return error("Cannot find linker input '" + File.toString() + "'");

  // If its an archive, try to link it in
  std::string Magic;
  File.getMagicNumber(Magic, 64);
  switch (sys::IdentifyFileType(Magic.c_str(), 64)) {
    default: llvm_unreachable("Bad file type identification");
    case sys::Unknown_FileType:
      return warning("Ignoring file '" + File.toString() + 
                   "' because does not contain bitcode.");

    case sys::Archive_FileType:
      // A user may specify an ar archive without -l, perhaps because it
      // is not installed as a library. Detect that and link the archive.
      verbose("Linking archive file '" + File.toString() + "'");
      if (LinkInArchive(File, is_native))
        return true;
      break;

    case sys::Bitcode_FileType: {
      verbose("Linking bitcode file '" + File.toString() + "'");
      std::auto_ptr<Module> M(LoadObject(File));
      if (M.get() == 0)
        return error("Cannot load file '" + File.toString() + "': " + Error);
      if (LinkInModule(M.get(), &Error))
        return error("Cannot link file '" + File.toString() + "': " + Error);

      verbose("Linked in file '" + File.toString() + "'");
      break;
    }

    case sys::ELF_Relocatable_FileType:
    case sys::ELF_SharedObject_FileType:
    case sys::Mach_O_Object_FileType:
    case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
    case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
    case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
    case sys::COFF_FileType:
      is_native = true;
      break;
  }
  return false;
}

void llvm::DisplayGraph(const sys::Path &Filename, bool wait,
                        GraphProgram::Name program) {
  std::string ErrMsg;
#if HAVE_GRAPHVIZ
  sys::Path Graphviz(LLVM_PATH_GRAPHVIZ);

  std::vector<const char*> args;
  args.push_back(Graphviz.c_str());
  args.push_back(Filename.c_str());
  args.push_back(0);
  
  errs() << "Running 'Graphviz' program... ";
  if (sys::Program::ExecuteAndWait(Graphviz, &args[0],0,0,0,0,&ErrMsg))
    errs() << "Error viewing graph " << Filename.str() << ": " << ErrMsg
           << "\n";
  else
    Filename.eraseFromDisk();

#elif (HAVE_GV && (HAVE_DOT || HAVE_FDP || HAVE_NEATO || \
                   HAVE_TWOPI || HAVE_CIRCO))
  sys::Path PSFilename = Filename;
  PSFilename.appendSuffix("ps");

  sys::Path prog;

  // Set default grapher
#if HAVE_CIRCO
  prog = sys::Path(LLVM_PATH_CIRCO);
#endif
#if HAVE_TWOPI
  prog = sys::Path(LLVM_PATH_TWOPI);
#endif
#if HAVE_NEATO
  prog = sys::Path(LLVM_PATH_NEATO);
#endif
#if HAVE_FDP
  prog = sys::Path(LLVM_PATH_FDP);
#endif
#if HAVE_DOT
  prog = sys::Path(LLVM_PATH_DOT);
#endif

  // Find which program the user wants
#if HAVE_DOT
  if (program == GraphProgram::DOT)
    prog = sys::Path(LLVM_PATH_DOT);
#endif
#if (HAVE_FDP)
  if (program == GraphProgram::FDP)
    prog = sys::Path(LLVM_PATH_FDP);
#endif
#if (HAVE_NEATO)
  if (program == GraphProgram::NEATO)
    prog = sys::Path(LLVM_PATH_NEATO);
#endif
#if (HAVE_TWOPI)
  if (program == GraphProgram::TWOPI)
    prog = sys::Path(LLVM_PATH_TWOPI);
#endif
#if (HAVE_CIRCO)
  if (program == GraphProgram::CIRCO)
    prog = sys::Path(LLVM_PATH_CIRCO);
#endif

  std::vector<const char*> args;
  args.push_back(prog.c_str());
  args.push_back("-Tps");
  args.push_back("-Nfontname=Courier");
  args.push_back("-Gsize=7.5,10");
  args.push_back(Filename.c_str());
  args.push_back("-o");
  args.push_back(PSFilename.c_str());
  args.push_back(0);
  
  errs() << "Running '" << prog.str() << "' program... ";

  if (sys::Program::ExecuteAndWait(prog, &args[0], 0, 0, 0, 0, &ErrMsg)) {
     errs() << "Error viewing graph " << Filename.str() << ": '"
            << ErrMsg << "\n";
  } else {
    errs() << " done. \n";

    sys::Path gv(LLVM_PATH_GV);
    args.clear();
    args.push_back(gv.c_str());
    args.push_back(PSFilename.c_str());
    args.push_back("--spartan");
    args.push_back(0);
    
    ErrMsg.clear();
    if (wait) {
       if (sys::Program::ExecuteAndWait(gv, &args[0],0,0,0,0,&ErrMsg))
          errs() << "Error viewing graph: " << ErrMsg << "\n";
       Filename.eraseFromDisk();
       PSFilename.eraseFromDisk();
    }
    else {
       sys::Program::ExecuteNoWait(gv, &args[0],0,0,0,&ErrMsg);
       errs() << "Remember to erase graph files: " << Filename.str() << " "
              << PSFilename.str() << "\n";
//.........这里部分代码省略.........

/// GenerateNative - generates a native object file from the
/// specified bitcode file.
///
/// Inputs:
///  InputFilename   - The name of the input bitcode file.
///  OutputFilename  - The name of the file to generate.
///  NativeLinkItems - The native libraries, files, code with which to link
///  LibPaths        - The list of directories in which to find libraries.
///  FrameworksPaths - The list of directories in which to find frameworks.
///  Frameworks      - The list of frameworks (dynamic libraries)
///  gcc             - The pathname to use for GGC.
///  envp            - A copy of the process's current environment.
///
/// Outputs:
///  None.
///
/// Returns non-zero value on error.
///
static int GenerateNative(const std::string &OutputFilename,
                          const std::string &InputFilename,
                          const Linker::ItemList &LinkItems,
                          const sys::Path &gcc, char ** const envp,
                          std::string& ErrMsg) {
  // Remove these environment variables from the environment of the
  // programs that we will execute.  It appears that GCC sets these
  // environment variables so that the programs it uses can configure
  // themselves identically.
  //
  // However, when we invoke GCC below, we want it to use its normal
  // configuration.  Hence, we must sanitize its environment.
  char ** clean_env = CopyEnv(envp);
  if (clean_env == NULL)
    return 1;
  RemoveEnv("LIBRARY_PATH", clean_env);
  RemoveEnv("COLLECT_GCC_OPTIONS", clean_env);
  RemoveEnv("GCC_EXEC_PREFIX", clean_env);
  RemoveEnv("COMPILER_PATH", clean_env);
  RemoveEnv("COLLECT_GCC", clean_env);


  // Run GCC to assemble and link the program into native code.
  //
  // Note:
  //  We can't just assemble and link the file with the system assembler
  //  and linker because we don't know where to put the _start symbol.
  //  GCC mysteriously knows how to do it.
  std::vector<std::string> args;
  args.push_back(gcc.c_str());
  args.push_back("-fno-strict-aliasing");
  args.push_back("-O3");
  args.push_back("-o");
  args.push_back(OutputFilename);
  args.push_back(InputFilename);

  // Add in the library and framework paths
  for (unsigned index = 0; index < LibPaths.size(); index++) {
    args.push_back("-L" + LibPaths[index]);
  }
  for (unsigned index = 0; index < FrameworkPaths.size(); index++) {
    args.push_back("-F" + FrameworkPaths[index]);
  }

  // Add the requested options
  for (unsigned index = 0; index < XLinker.size(); index++)
    args.push_back(XLinker[index]);

  // Add in the libraries to link.
  for (unsigned index = 0; index < LinkItems.size(); index++)
    if (LinkItems[index].first != "crtend") {
      if (LinkItems[index].second)
        args.push_back("-l" + LinkItems[index].first);
      else
        args.push_back(LinkItems[index].first);
    }

  // Add in frameworks to link.
  for (unsigned index = 0; index < Frameworks.size(); index++) {
    args.push_back("-framework");
    args.push_back(Frameworks[index]);
  }

  // Now that "args" owns all the std::strings for the arguments, call the c_str
  // method to get the underlying string array.  We do this game so that the
  // std::string array is guaranteed to outlive the const char* array.
  std::vector<const char *> Args;
  for (unsigned i = 0, e = args.size(); i != e; ++i)
    Args.push_back(args[i].c_str());
  Args.push_back(0);

  if (Verbose) {
    errs() << "Generating Native Executable With:\n";
    PrintCommand(Args);
  }

  // Run the compiler to assembly and link together the program.
  int R = sys::Program::ExecuteAndWait(
    gcc, &Args[0], const_cast<const char **>(clean_env), 0, 0, 0, &ErrMsg);
  delete [] clean_env;
  return R;
}

void llvm::DisplayGraph(const sys::Path &Filename, bool wait,
                        GraphProgram::Name program) {
  wait &= !ViewBackground;
  std::string ErrMsg;
#if HAVE_GRAPHVIZ
  sys::Path Graphviz(LLVM_PATH_GRAPHVIZ);

  std::vector<const char*> args;
  args.push_back(Graphviz.c_str());
  args.push_back(Filename.c_str());
  args.push_back(0);

  errs() << "Running 'Graphviz' program... ";
  if (!ExecGraphViewer(Graphviz, args, Filename, wait, ErrMsg))
    return;

#elif HAVE_XDOT_PY
  std::vector<const char*> args;
  args.push_back(LLVM_PATH_XDOT_PY);
  args.push_back(Filename.c_str());

  switch (program) {
  case GraphProgram::DOT:   args.push_back("-f"); args.push_back("dot"); break;
  case GraphProgram::FDP:   args.push_back("-f"); args.push_back("fdp"); break;
  case GraphProgram::NEATO: args.push_back("-f"); args.push_back("neato");break;
  case GraphProgram::TWOPI: args.push_back("-f"); args.push_back("twopi");break;
  case GraphProgram::CIRCO: args.push_back("-f"); args.push_back("circo");break;
  }

  args.push_back(0);

  errs() << "Running 'xdot.py' program... ";
  if (!ExecGraphViewer(sys::Path(LLVM_PATH_XDOT_PY), args, Filename, wait, ErrMsg))
    return;

#elif (HAVE_GV && (HAVE_DOT || HAVE_FDP || HAVE_NEATO || \
                   HAVE_TWOPI || HAVE_CIRCO))
  sys::Path PSFilename = Filename;
  PSFilename.appendSuffix("ps");

  sys::Path prog;

  // Set default grapher
#if HAVE_CIRCO
  prog = sys::Path(LLVM_PATH_CIRCO);
#endif
#if HAVE_TWOPI
  prog = sys::Path(LLVM_PATH_TWOPI);
#endif
#if HAVE_NEATO
  prog = sys::Path(LLVM_PATH_NEATO);
#endif
#if HAVE_FDP
  prog = sys::Path(LLVM_PATH_FDP);
#endif
#if HAVE_DOT
  prog = sys::Path(LLVM_PATH_DOT);
#endif

  // Find which program the user wants
#if HAVE_DOT
  if (program == GraphProgram::DOT)
    prog = sys::Path(LLVM_PATH_DOT);
#endif
#if (HAVE_FDP)
  if (program == GraphProgram::FDP)
    prog = sys::Path(LLVM_PATH_FDP);
#endif
#if (HAVE_NEATO)
  if (program == GraphProgram::NEATO)
    prog = sys::Path(LLVM_PATH_NEATO);
#endif
#if (HAVE_TWOPI)
  if (program == GraphProgram::TWOPI)
    prog = sys::Path(LLVM_PATH_TWOPI);
#endif
#if (HAVE_CIRCO)
  if (program == GraphProgram::CIRCO)
    prog = sys::Path(LLVM_PATH_CIRCO);
#endif

  std::vector<const char*> args;
  args.push_back(prog.c_str());
  args.push_back("-Tps");
  args.push_back("-Nfontname=Courier");
  args.push_back("-Gsize=7.5,10");
  args.push_back(Filename.c_str());
  args.push_back("-o");
  args.push_back(PSFilename.c_str());
  args.push_back(0);

  errs() << "Running '" << prog.str() << "' program... ";

  if (!ExecGraphViewer(prog, args, Filename, wait, ErrMsg))
    return;

  sys::Path gv(LLVM_PATH_GV);
  args.clear();
  args.push_back(gv.c_str());
  args.push_back(PSFilename.c_str());
//.........这里部分代码省略.........

// This method allows an ArchiveMember to be replaced with the data for a
// different file, presumably as an update to the member. It also makes sure
// the flags are reset correctly.
bool ArchiveMember::replaceWith(const sys::Path& newFile, std::string* ErrMsg) {
  bool Exists;
  if (sys::fs::exists(newFile.str(), Exists) || !Exists) {
    if (ErrMsg)
      *ErrMsg = "Can not replace an archive member with a non-existent file";
    return true;
  }

  data = 0;
  path = newFile;

  // SVR4 symbol tables have an empty name
  if (path.str() == ARFILE_SVR4_SYMTAB_NAME)
    flags |= SVR4SymbolTableFlag;
  else
    flags &= ~SVR4SymbolTableFlag;

  // BSD4.4 symbol tables have a special name
  if (path.str() == ARFILE_BSD4_SYMTAB_NAME)
    flags |= BSD4SymbolTableFlag;
  else
    flags &= ~BSD4SymbolTableFlag;

  // LLVM symbol tables have a very specific name
  if (path.str() == ARFILE_LLVM_SYMTAB_NAME)
    flags |= LLVMSymbolTableFlag;
  else
    flags &= ~LLVMSymbolTableFlag;

  // String table name
  if (path.str() == ARFILE_STRTAB_NAME)
    flags |= StringTableFlag;
  else
    flags &= ~StringTableFlag;

  // If it has a slash then it has a path
  bool hasSlash = path.str().find('/') != std::string::npos;
  if (hasSlash)
    flags |= HasPathFlag;
  else
    flags &= ~HasPathFlag;

  // If it has a slash or its over 15 chars then its a long filename format
  if (hasSlash || path.str().length() > 15)
    flags |= HasLongFilenameFlag;
  else
    flags &= ~HasLongFilenameFlag;

  // Get the signature and status info
  const char* signature = (const char*) data;
  SmallString<4> magic;
  if (!signature) {
    sys::fs::get_magic(path.str(), magic.capacity(), magic);
    signature = magic.c_str();
    const sys::FileStatus *FSinfo = path.getFileStatus(false, ErrMsg);
    if (FSinfo)
      info = *FSinfo;
    else
      return true;
  }

  // Determine what kind of file it is.
  switch (sys::IdentifyFileType(signature,4)) {
    case sys::Bitcode_FileType:
      flags |= BitcodeFlag;
      break;
    default:
      flags &= ~BitcodeFlag;
      break;
  }
  return false;
}

/// LinkInFile - opens a bitcode file and links in all objects which
/// provide symbols that are currently undefined.
///
/// Inputs:
///  File - The pathname of the bitcode file.
///
/// Outputs:
///  ErrorMessage - A C++ string detailing what error occurred, if any.
///
/// Return Value:
///  TRUE  - An error occurred.
///  FALSE - No errors.
///
bool Linker::LinkInFile(const sys::Path &File, bool &is_native) {
  is_native = false;
  
  // Check for a file of name "-", which means "read standard input"
  if (File.str() == "-") {
    std::auto_ptr<Module> M;
    OwningPtr<MemoryBuffer> Buffer;
    error_code ec;
    if (!(ec = MemoryBuffer::getSTDIN(Buffer))) {
      if (!Buffer->getBufferSize()) {
        Error = "standard input is empty";
      } else {
        M.reset(ParseBitcodeFile(Buffer.get(), Context, &Error));
        if (M.get())
          if (!LinkInModule(M.get(), &Error))
            return false;
      }
    }
    return error("Cannot link stdin: " + ec.message());
  }

  // Determine what variety of file it is.
  std::string Magic;
  if (!File.getMagicNumber(Magic, 512))
    return error("Cannot find linker input '" + File.str() + "'");

  switch (sys::IdentifyFileType(Magic.c_str(), 512)) {
    default: llvm_unreachable("Bad file type identification");
    case sys::Unknown_FileType:
      return warning("Ignoring file '" + File.str() + 
                   "' because does not contain bitcode.");

    case sys::Archive_FileType:
      // A user may specify an ar archive without -l, perhaps because it
      // is not installed as a library. Detect that and link the archive.
      if (LinkInArchive(File, is_native))
        return true;
      break;

    case sys::Bitcode_FileType: {
      verbose("Linking bitcode file '" + File.str() + "'");
      std::auto_ptr<Module> M(LoadObject(File));
      if (M.get() == 0)
        return error("Cannot load file '" + File.str() + "': " + Error);
      if (LinkInModule(M.get(), &Error))
        return error("Cannot link file '" + File.str() + "': " + Error);

      verbose("Linked in file '" + File.str() + "'");
      break;
    }

    case sys::ELF_Relocatable_FileType:
    case sys::ELF_SharedObject_FileType:
    case sys::Mach_O_Object_FileType:
    case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
    case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
    case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
    case sys::COFF_FileType:
      is_native = true;
      break;
  }
  return false;
}