text: //===--- Driver.cpp - Clang GCC Compatible Driver -------------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  
  #include "clang/Driver/Driver.h"
  #include "InputInfo.h"
  #include "ToolChains.h"
  #include "clang/Basic/Version.h"
  #include "clang/Config/config.h"
  #include "clang/Driver/Action.h"
  #include "clang/Driver/Compilation.h"
  #include "clang/Driver/DriverDiagnostic.h"
  #include "clang/Driver/Job.h"
  #include "clang/Driver/Options.h"
  #include "clang/Driver/Tool.h"
  #include "clang/Driver/ToolChain.h"
  #include "llvm/ADT/ArrayRef.h"
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ADT/StringExtras.h"
  #include "llvm/ADT/StringSet.h"
  #include "llvm/ADT/StringSwitch.h"
  #include "llvm/Option/Arg.h"
  #include "llvm/Option/ArgList.h"
  #include "llvm/Option/OptSpecifier.h"
  #include "llvm/Option/OptTable.h"
  #include "llvm/Option/Option.h"
  #include "llvm/Support/Debug.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/FileSystem.h"
  #include "llvm/Support/Path.h"
  #include "llvm/Support/PrettyStackTrace.h"
  #include "llvm/Support/Process.h"
  #include "llvm/Support/Program.h"
  #include "llvm/Support/raw_ostream.h"
  #include <map>
  #include <memory>
  
  using namespace clang::driver;
  using namespace clang;
  using namespace llvm::opt;
  
  Driver::Driver(StringRef ClangExecutable,
                 StringRef DefaultTargetTriple,
                 DiagnosticsEngine &Diags)
    : Opts(createDriverOptTable()), Diags(Diags), Mode(GCCMode),
      ClangExecutable(ClangExecutable), SysRoot(DEFAULT_SYSROOT),
      UseStdLib(true), DefaultTargetTriple(DefaultTargetTriple),
      DefaultImageName("a.out"),
      DriverTitle("clang LLVM compiler"),
      CCPrintOptionsFilename(nullptr), CCPrintHeadersFilename(nullptr),
      CCLogDiagnosticsFilename(nullptr),
      CCCPrintBindings(false),
      CCPrintHeaders(false), CCLogDiagnostics(false),
      CCGenDiagnostics(false), CCCGenericGCCName(""), CheckInputsExist(true),
      CCCUsePCH(true), SuppressMissingInputWarning(false) {
  
    Name = llvm::sys::path::stem(ClangExecutable);
    Dir  = llvm::sys::path::parent_path(ClangExecutable);
  
    // Compute the path to the resource directory.
    StringRef ClangResourceDir(CLANG_RESOURCE_DIR);
    SmallString<128> P(Dir);
    if (ClangResourceDir != "")
      llvm::sys::path::append(P, ClangResourceDir);
    else
      llvm::sys::path::append(P, "..", "lib", "clang", CLANG_VERSION_STRING);
    ResourceDir = P.str();
  }
  
  Driver::~Driver() {
    delete Opts;
  
    llvm::DeleteContainerSeconds(ToolChains);
  }
  
  void Driver::ParseDriverMode(ArrayRef<const char *> Args) {
    const std::string OptName =
      getOpts().getOption(options::OPT_driver_mode).getPrefixedName();
  
    for (size_t I = 0, E = Args.size(); I != E; ++I) {
      // Ingore nullptrs, they are response file's EOL markers
      if (Args[I] == nullptr)
        continue;
      const StringRef Arg = Args[I];
      if (!Arg.startswith(OptName))
        continue;
  
      const StringRef Value = Arg.drop_front(OptName.size());
      const unsigned M = llvm::StringSwitch<unsigned>(Value)
          .Case("gcc", GCCMode)
          .Case("g++", GXXMode)
          .Case("cpp", CPPMode)
          .Case("cl",  CLMode)
          .Default(~0U);
  
      if (M != ~0U)
        Mode = static_cast<DriverMode>(M);
      else
        Diag(diag::err_drv_unsupported_option_argument) << OptName << Value;
    }
  }
  
  InputArgList *Driver::ParseArgStrings(ArrayRef<const char *> ArgStrings) {
    llvm::PrettyStackTraceString CrashInfo("Command line argument parsing");
  
    unsigned IncludedFlagsBitmask;
    unsigned ExcludedFlagsBitmask;
    std::tie(IncludedFlagsBitmask, ExcludedFlagsBitmask) =
      getIncludeExcludeOptionFlagMasks();
  
    unsigned MissingArgIndex, MissingArgCount;
    InputArgList *Args = getOpts().ParseArgs(ArgStrings.begin(), ArgStrings.end(),
                                             MissingArgIndex, MissingArgCount,
                                             IncludedFlagsBitmask,
                                             ExcludedFlagsBitmask);
  
    // Check for missing argument error.
    if (MissingArgCount)
      Diag(clang::diag::err_drv_missing_argument)
        << Args->getArgString(MissingArgIndex) << MissingArgCount;
  
    // Check for unsupported options.
    for (ArgList::const_iterator it = Args->begin(), ie = Args->end();
         it != ie; ++it) {
      Arg *A = *it;
      if (A->getOption().hasFlag(options::Unsupported)) {
        Diag(clang::diag::err_drv_unsupported_opt) << A->getAsString(*Args);
        continue;
      }
  
      // Warn about -mcpu= without an argument.
      if (A->getOption().matches(options::OPT_mcpu_EQ) &&
          A->containsValue("")) {
        Diag(clang::diag::warn_drv_empty_joined_argument) <<
          A->getAsString(*Args);
      }
    }
  
    for (arg_iterator it = Args->filtered_begin(options::OPT_UNKNOWN),
           ie = Args->filtered_end(); it != ie; ++it) {
      Diags.Report(diag::err_drv_unknown_argument) << (*it) ->getAsString(*Args);
    }
  
    return Args;
  }
  
  // Determine which compilation mode we are in. We look for options which
  // affect the phase, starting with the earliest phases, and record which
  // option we used to determine the final phase.
  phases::ID Driver::getFinalPhase(const DerivedArgList &DAL, Arg **FinalPhaseArg)
  const {
    Arg *PhaseArg = nullptr;
    phases::ID FinalPhase;
  
    // -{E,EP,P,M,MM} only run the preprocessor.
    if (CCCIsCPP() ||
        (PhaseArg = DAL.getLastArg(options::OPT_E)) ||
        (PhaseArg = DAL.getLastArg(options::OPT__SLASH_EP)) ||
        (PhaseArg = DAL.getLastArg(options::OPT_M, options::OPT_MM)) ||
        (PhaseArg = DAL.getLastArg(options::OPT__SLASH_P))) {
      FinalPhase = phases::Preprocess;
  
      // -{fsyntax-only,-analyze,emit-ast,S} only run up to the compiler.
    } else if ((PhaseArg = DAL.getLastArg(options::OPT_fsyntax_only)) ||
               (PhaseArg = DAL.getLastArg(options::OPT_module_file_info)) ||
               (PhaseArg = DAL.getLastArg(options::OPT_verify_pch)) ||
               (PhaseArg = DAL.getLastArg(options::OPT_rewrite_objc)) ||
               (PhaseArg = DAL.getLastArg(options::OPT_rewrite_legacy_objc)) ||
               (PhaseArg = DAL.getLastArg(options::OPT__migrate)) ||
               (PhaseArg = DAL.getLastArg(options::OPT__analyze,
                                          options::OPT__analyze_auto)) ||
               (PhaseArg = DAL.getLastArg(options::OPT_emit_ast)) ||
               (PhaseArg = DAL.getLastArg(options::OPT_S))) {
      FinalPhase = phases::Compile;
  
      // -c only runs up to the assembler.
    } else if ((PhaseArg = DAL.getLastArg(options::OPT_c))) {
      FinalPhase = phases::Assemble;
  
      // Otherwise do everything.
    } else
      FinalPhase = phases::Link;
  
    if (FinalPhaseArg)
      *FinalPhaseArg = PhaseArg;
  
    return FinalPhase;
  }
  
  static Arg* MakeInputArg(DerivedArgList &Args, OptTable *Opts,
                           StringRef Value) {
    Arg *A = new Arg(Opts->getOption(options::OPT_INPUT), Value,
                     Args.getBaseArgs().MakeIndex(Value), Value.data());
    Args.AddSynthesizedArg(A);
    A->claim();
    return A;
  }
  
  DerivedArgList *Driver::TranslateInputArgs(const InputArgList &Args) const {
    DerivedArgList *DAL = new DerivedArgList(Args);
  
    bool HasNostdlib = Args.hasArg(options::OPT_nostdlib);
    for (ArgList::const_iterator it = Args.begin(),
           ie = Args.end(); it != ie; ++it) {
      const Arg *A = *it;
  
      // Unfortunately, we have to parse some forwarding options (-Xassembler,
      // -Xlinker, -Xpreprocessor) because we either integrate their functionality
      // (assembler and preprocessor), or bypass a previous driver ('collect2').
  
      // Rewrite linker options, to replace --no-demangle with a custom internal
      // option.
      if ((A->getOption().matches(options::OPT_Wl_COMMA) ||
           A->getOption().matches(options::OPT_Xlinker)) &&
          A->containsValue("--no-demangle")) {
        // Add the rewritten no-demangle argument.
        DAL->AddFlagArg(A, Opts->getOption(options::OPT_Z_Xlinker__no_demangle));
  
        // Add the remaining values as Xlinker arguments.
        for (unsigned i = 0, e = A->getNumValues(); i != e; ++i)
          if (StringRef(A->getValue(i)) != "--no-demangle")
            DAL->AddSeparateArg(A, Opts->getOption(options::OPT_Xlinker),
                                A->getValue(i));
  
        continue;
      }
  
      // Rewrite preprocessor options, to replace -Wp,-MD,FOO which is used by
      // some build systems. We don't try to be complete here because we don't
      // care to encourage this usage model.
      if (A->getOption().matches(options::OPT_Wp_COMMA) &&
          (A->getValue(0) == StringRef("-MD") ||
           A->getValue(0) == StringRef("-MMD"))) {
        // Rewrite to -MD/-MMD along with -MF.
        if (A->getValue(0) == StringRef("-MD"))
          DAL->AddFlagArg(A, Opts->getOption(options::OPT_MD));
        else
          DAL->AddFlagArg(A, Opts->getOption(options::OPT_MMD));
        if (A->getNumValues() == 2)
          DAL->AddSeparateArg(A, Opts->getOption(options::OPT_MF),
                              A->getValue(1));
        continue;
      }
  
      // Rewrite reserved library names.
      if (A->getOption().matches(options::OPT_l)) {
        StringRef Value = A->getValue();
  
        // Rewrite unless -nostdlib is present.
        if (!HasNostdlib && Value == "stdc++") {
          DAL->AddFlagArg(A, Opts->getOption(
                                options::OPT_Z_reserved_lib_stdcxx));
          continue;
        }
  
        // Rewrite unconditionally.
        if (Value == "cc_kext") {
          DAL->AddFlagArg(A, Opts->getOption(
                                options::OPT_Z_reserved_lib_cckext));
          continue;
        }
      }
  
      // Pick up inputs via the -- option.
      if (A->getOption().matches(options::OPT__DASH_DASH)) {
        A->claim();
        for (unsigned i = 0, e = A->getNumValues(); i != e; ++i)
          DAL->append(MakeInputArg(*DAL, Opts, A->getValue(i)));
        continue;
      }
  
      DAL->append(*it);
    }
  
    // Add a default value of -mlinker-version=, if one was given and the user
    // didn't specify one.
  #if defined(HOST_LINK_VERSION)
    if (!Args.hasArg(options::OPT_mlinker_version_EQ)) {
      DAL->AddJoinedArg(0, Opts->getOption(options::OPT_mlinker_version_EQ),
                        HOST_LINK_VERSION);
      DAL->getLastArg(options::OPT_mlinker_version_EQ)->claim();
    }
  #endif
  
    return DAL;
  }
  
  Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
    llvm::PrettyStackTraceString CrashInfo("Compilation construction");
  
    // FIXME: Handle environment options which affect driver behavior, somewhere
    // (client?). GCC_EXEC_PREFIX, LPATH, CC_PRINT_OPTIONS.
  
    if (char *env = ::getenv("COMPILER_PATH")) {
      StringRef CompilerPath = env;
      while (!CompilerPath.empty()) {
        std::pair<StringRef, StringRef> Split
          = CompilerPath.split(llvm::sys::EnvPathSeparator);
        PrefixDirs.push_back(Split.first);
        CompilerPath = Split.second;
      }
    }
  
    // We look for the driver mode option early, because the mode can affect
    // how other options are parsed.
    ParseDriverMode(ArgList.slice(1));
  
    // FIXME: What are we going to do with -V and -b?
  
    // FIXME: This stuff needs to go into the Compilation, not the driver.
    bool CCCPrintActions;
  
    InputArgList *Args = ParseArgStrings(ArgList.slice(1));
  
    // -no-canonical-prefixes is used very early in main.
    Args->ClaimAllArgs(options::OPT_no_canonical_prefixes);
  
    // Ignore -pipe.
    Args->ClaimAllArgs(options::OPT_pipe);
  
    // Extract -ccc args.
    //
    // FIXME: We need to figure out where this behavior should live. Most of it
    // should be outside in the client; the parts that aren't should have proper
    // options, either by introducing new ones or by overloading gcc ones like -V
    // or -b.
    CCCPrintActions = Args->hasArg(options::OPT_ccc_print_phases);
    CCCPrintBindings = Args->hasArg(options::OPT_ccc_print_bindings);
    if (const Arg *A = Args->getLastArg(options::OPT_ccc_gcc_name))
      CCCGenericGCCName = A->getValue();
    CCCUsePCH = Args->hasFlag(options::OPT_ccc_pch_is_pch,
                              options::OPT_ccc_pch_is_pth);
    // FIXME: DefaultTargetTriple is used by the target-prefixed calls to as/ld
    // and getToolChain is const.
    if (IsCLMode()) {
      // clang-cl targets MSVC-style Win32.
      llvm::Triple T(DefaultTargetTriple);
      T.setOS(llvm::Triple::Win32);
      T.setEnvironment(llvm::Triple::MSVC);
      DefaultTargetTriple = T.str();
    }
    if (const Arg *A = Args->getLastArg(options::OPT_target))
      DefaultTargetTriple = A->getValue();
    if (const Arg *A = Args->getLastArg(options::OPT_ccc_install_dir))
      Dir = InstalledDir = A->getValue();
    for (arg_iterator it = Args->filtered_begin(options::OPT_B),
           ie = Args->filtered_end(); it != ie; ++it) {
      const Arg *A = *it;
      A->claim();
      PrefixDirs.push_back(A->getValue(0));
    }
    if (const Arg *A = Args->getLastArg(options::OPT__sysroot_EQ))
      SysRoot = A->getValue();
    if (const Arg *A = Args->getLastArg(options::OPT__dyld_prefix_EQ))
      DyldPrefix = A->getValue();
    if (Args->hasArg(options::OPT_nostdlib))
      UseStdLib = false;
  
    if (const Arg *A = Args->getLastArg(options::OPT_resource_dir))
      ResourceDir = A->getValue();
  
    // Perform the default argument translations.
    DerivedArgList *TranslatedArgs = TranslateInputArgs(*Args);
  
    // Owned by the host.
    const ToolChain &TC = getToolChain(*Args);
  
    // The compilation takes ownership of Args.
    Compilation *C = new Compilation(*this, TC, Args, TranslatedArgs);
  
    if (!HandleImmediateArgs(*C))
      return C;
  
    // Construct the list of inputs.
    InputList Inputs;
    BuildInputs(C->getDefaultToolChain(), *TranslatedArgs, Inputs);
  
    // Construct the list of abstract actions to perform for this compilation. On
    // MachO targets this uses the driver-driver and universal actions.
    if (TC.getTriple().isOSBinFormatMachO())
      BuildUniversalActions(C->getDefaultToolChain(), C->getArgs(),
                            Inputs, C->getActions());
    else
      BuildActions(C->getDefaultToolChain(), C->getArgs(), Inputs,
                   C->getActions());
  
    if (CCCPrintActions) {
      PrintActions(*C);
      return C;
    }
  
    BuildJobs(*C);
  
    return C;
  }
  
  // When clang crashes, produce diagnostic information including the fully
  // preprocessed source file(s).  Request that the developer attach the
  // diagnostic information to a bug report.
  void Driver::generateCompilationDiagnostics(Compilation &C,
                                              const Command &FailingCommand) {
    if (C.getArgs().hasArg(options::OPT_fno_crash_diagnostics))
      return;
  
    // Don't try to generate diagnostics for link or dsymutil jobs.
    if (FailingCommand.getCreator().isLinkJob() ||
        FailingCommand.getCreator().isDsymutilJob())
      return;
  
    // Print the version of the compiler.
    PrintVersion(C, llvm::errs());
  
    Diag(clang::diag::note_drv_command_failed_diag_msg)
      << "PLEASE submit a bug report to " BUG_REPORT_URL " and include the "
      "crash backtrace, preprocessed source, and associated run script.";
  
    // Suppress driver output and emit preprocessor output to temp file.
    Mode = CPPMode;
    CCGenDiagnostics = true;
  
    // Save the original job command(s).
    Command Cmd = FailingCommand;
  
    // Keep track of whether we produce any errors while trying to produce
    // preprocessed sources.
    DiagnosticErrorTrap Trap(Diags);
  
    // Suppress tool output.
    C.initCompilationForDiagnostics();
  
    // Construct the list of inputs.
    InputList Inputs;
    BuildInputs(C.getDefaultToolChain(), C.getArgs(), Inputs);
  
    for (InputList::iterator it = Inputs.begin(), ie = Inputs.end(); it != ie;) {
      bool IgnoreInput = false;
  
      // Ignore input from stdin or any inputs that cannot be preprocessed.
      // Check type first as not all linker inputs have a value.
     if (types::getPreprocessedType(it->first) == types::TY_INVALID) {
        IgnoreInput = true;
      } else if (!strcmp(it->second->getValue(), "-")) {
        Diag(clang::diag::note_drv_command_failed_diag_msg)
          << "Error generating preprocessed source(s) - ignoring input from stdin"
          ".";
        IgnoreInput = true;
      }
  
      if (IgnoreInput) {
        it = Inputs.erase(it);
        ie = Inputs.end();
      } else {
        ++it;
      }
    }
  
    if (Inputs.empty()) {
      Diag(clang::diag::note_drv_command_failed_diag_msg)
        << "Error generating preprocessed source(s) - no preprocessable inputs.";
      return;
    }
  
    // Don't attempt to generate preprocessed files if multiple -arch options are
    // used, unless they're all duplicates.
    llvm::StringSet<> ArchNames;
    for (ArgList::const_iterator it = C.getArgs().begin(), ie = C.getArgs().end();
         it != ie; ++it) {
      Arg *A = *it;
      if (A->getOption().matches(options::OPT_arch)) {
        StringRef ArchName = A->getValue();
        ArchNames.insert(ArchName);
      }
    }
    if (ArchNames.size() > 1) {
      Diag(clang::diag::note_drv_command_failed_diag_msg)
        << "Error generating preprocessed source(s) - cannot generate "
        "preprocessed source with multiple -arch options.";
      return;
    }
  
    // Construct the list of abstract actions to perform for this compilation. On
    // Darwin OSes this uses the driver-driver and builds universal actions.
    const ToolChain &TC = C.getDefaultToolChain();
    if (TC.getTriple().isOSBinFormatMachO())
      BuildUniversalActions(TC, C.getArgs(), Inputs, C.getActions());
    else
      BuildActions(TC, C.getArgs(), Inputs, C.getActions());
  
    BuildJobs(C);
  
    // If there were errors building the compilation, quit now.
    if (Trap.hasErrorOccurred()) {
      Diag(clang::diag::note_drv_command_failed_diag_msg)
        << "Error generating preprocessed source(s).";
      return;
    }
  
    // Generate preprocessed output.
    SmallVector<std::pair<int, const Command *>, 4> FailingCommands;
    C.ExecuteJob(C.getJobs(), FailingCommands);
  
    // If any of the preprocessing commands failed, clean up and exit.
    if (!FailingCommands.empty()) {
      if (!C.getArgs().hasArg(options::OPT_save_temps))
        C.CleanupFileList(C.getTempFiles(), true);
  
      Diag(clang::diag::note_drv_command_failed_diag_msg)
        << "Error generating preprocessed source(s).";
      return;
    }
  
    const ArgStringList &TempFiles = C.getTempFiles();
    if (TempFiles.empty()) {
      Diag(clang::diag::note_drv_command_failed_diag_msg)
        << "Error generating preprocessed source(s).";
      return;
    }
  
    Diag(clang::diag::note_drv_command_failed_diag_msg)
        << "\n********************\n\n"
           "PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:\n"
           "Preprocessed source(s) and associated run script(s) are located at:";
  
    SmallString<128> VFS;
    for (const char *TempFile : TempFiles) {
      Diag(clang::diag::note_drv_command_failed_diag_msg) << TempFile;
      if (StringRef(TempFile).endswith(".cache")) {
        // In some cases (modules) we'll dump extra data to help with reproducing
        // the crash into a directory next to the output.
        VFS = llvm::sys::path::filename(TempFile);
        llvm::sys::path::append(VFS, "vfs", "vfs.yaml");
      }
    }
  
    // Assume associated files are based off of the first temporary file.
    CrashReportInfo CrashInfo(TempFiles[0], VFS);
  
    std::string Script = CrashInfo.Filename.rsplit('.').first.str() + ".sh";
    std::error_code EC;
    llvm::raw_fd_ostream ScriptOS(Script, EC, llvm::sys::fs::F_Excl);
    if (EC) {
      Diag(clang::diag::note_drv_command_failed_diag_msg)
          << "Error generating run script: " + Script + " " + EC.message();
    } else {
      Cmd.Print(ScriptOS, "\n", /*Quote=*/true, &CrashInfo);
      Diag(clang::diag::note_drv_command_failed_diag_msg) << Script;
    }
    Diag(clang::diag::note_drv_command_failed_diag_msg)
        << "\n\n********************";
  }
  
  void Driver::setUpResponseFiles(Compilation &C, Job &J) {
    if (JobList *Jobs = dyn_cast<JobList>(&J)) {
      for (auto &Job : *Jobs)
        setUpResponseFiles(C, Job);
      return;
    }
  
    Command *CurCommand = dyn_cast<Command>(&J);
    if (!CurCommand)
      return;
  
    // Since argumentsFitWithinSystemLimits() may underestimate system's capacity
    // if the tool does not support response files, there is a chance/ that things
    // will just work without a response file, so we silently just skip it.
    if (CurCommand->getCreator().getResponseFilesSupport() == Tool::RF_None ||
        llvm::sys::argumentsFitWithinSystemLimits(CurCommand->getArguments()))
      return;
  
    std::string TmpName = GetTemporaryPath("response", "txt");
    CurCommand->setResponseFile(C.addTempFile(C.getArgs().MakeArgString(
        TmpName.c_str())));
  }
  
  int Driver::ExecuteCompilation(Compilation &C,
      SmallVectorImpl< std::pair<int, const Command *> > &FailingCommands) {
    // Just print if -### was present.
    if (C.getArgs().hasArg(options::OPT__HASH_HASH_HASH)) {
      C.getJobs().Print(llvm::errs(), "\n", true);
      return 0;
    }
  
    // If there were errors building the compilation, quit now.
    if (Diags.hasErrorOccurred())
      return 1;
  
    // Set up response file names for each command, if necessary
    setUpResponseFiles(C, C.getJobs());
  
    C.ExecuteJob(C.getJobs(), FailingCommands);
  
    // Remove temp files.
    C.CleanupFileList(C.getTempFiles());
  
    // If the command succeeded, we are done.
    if (FailingCommands.empty())
      return 0;
  
    // Otherwise, remove result files and print extra information about abnormal
    // failures.
    for (SmallVectorImpl< std::pair<int, const Command *> >::iterator it =
           FailingCommands.begin(), ie = FailingCommands.end(); it != ie; ++it) {
      int Res = it->first;
      const Command *FailingCommand = it->second;
  
      // Remove result files if we're not saving temps.
      if (!C.getArgs().hasArg(options::OPT_save_temps)) {
        const JobAction *JA = cast<JobAction>(&FailingCommand->getSource());
        C.CleanupFileMap(C.getResultFiles(), JA, true);
  
        // Failure result files are valid unless we crashed.
        if (Res < 0)
          C.CleanupFileMap(C.getFailureResultFiles(), JA, true);
      }
  
      // Print extra information about abnormal failures, if possible.
      //
      // This is ad-hoc, but we don't want to be excessively noisy. If the result
      // status was 1, assume the command failed normally. In particular, if it
      // was the compiler then assume it gave a reasonable error code. Failures
      // in other tools are less common, and they generally have worse
      // diagnostics, so always print the diagnostic there.
      const Tool &FailingTool = FailingCommand->getCreator();
  
      if (!FailingCommand->getCreator().hasGoodDiagnostics() || Res != 1) {
        // FIXME: See FIXME above regarding result code interpretation.
        if (Res < 0)
          Diag(clang::diag::err_drv_command_signalled)
            << FailingTool.getShortName();
        else
          Diag(clang::diag::err_drv_command_failed)
            << FailingTool.getShortName() << Res;
      }
    }
    return 0;
  }
  
  void Driver::PrintHelp(bool ShowHidden) const {
    unsigned IncludedFlagsBitmask;
    unsigned ExcludedFlagsBitmask;
    std::tie(IncludedFlagsBitmask, ExcludedFlagsBitmask) =
      getIncludeExcludeOptionFlagMasks();
  
    ExcludedFlagsBitmask |= options::NoDriverOption;
    if (!ShowHidden)
      ExcludedFlagsBitmask |= HelpHidden;
  
    getOpts().PrintHelp(llvm::outs(), Name.c_str(), DriverTitle.c_str(),
                        IncludedFlagsBitmask, ExcludedFlagsBitmask);
  }
  
  void Driver::PrintVersion(const Compilation &C, raw_ostream &OS) const {
    // FIXME: The following handlers should use a callback mechanism, we don't
    // know what the client would like to do.
    OS << getClangFullVersion() << '\n';
    const ToolChain &TC = C.getDefaultToolChain();
    OS << "Target: " << TC.getTripleString() << '\n';
  
    // Print the threading model.
    if (Arg *A = C.getArgs().getLastArg(options::OPT_mthread_model)) {
      // Don't print if the ToolChain would have barfed on it already
      if (TC.isThreadModelSupported(A->getValue()))
        OS << "Thread model: " << A->getValue();
    } else
      OS << "Thread model: " << TC.getThreadModel();
    OS << '\n';
  }
  
  /// PrintDiagnosticCategories - Implement the --print-diagnostic-categories
  /// option.
  static void PrintDiagnosticCategories(raw_ostream &OS) {
    // Skip the empty category.
    for (unsigned i = 1, max = DiagnosticIDs::getNumberOfCategories();
         i != max; ++i)
      OS << i << ',' << DiagnosticIDs::getCategoryNameFromID(i) << '\n';
  }
  
  bool Driver::HandleImmediateArgs(const Compilation &C) {
    // The order these options are handled in gcc is all over the place, but we
    // don't expect inconsistencies w.r.t. that to matter in practice.
  
    if (C.getArgs().hasArg(options::OPT_dumpmachine)) {
      llvm::outs() << C.getDefaultToolChain().getTripleString() << '\n';
      return false;
    }
  
    if (C.getArgs().hasArg(options::OPT_dumpversion)) {
      // Since -dumpversion is only implemented for pedantic GCC compatibility, we
      // return an answer which matches our definition of __VERSION__.
      //
      // If we want to return a more correct answer some day, then we should
      // introduce a non-pedantically GCC compatible mode to Clang in which we
      // provide sensible definitions for -dumpversion, __VERSION__, etc.
      llvm::outs() << "4.2.1\n";
      return false;
    }
  
    if (C.getArgs().hasArg(options::OPT__print_diagnostic_categories)) {
      PrintDiagnosticCategories(llvm::outs());
      return false;
    }
  
    if (C.getArgs().hasArg(options::OPT_help) ||
        C.getArgs().hasArg(options::OPT__help_hidden)) {
      PrintHelp(C.getArgs().hasArg(options::OPT__help_hidden));
      return false;
    }
  
    if (C.getArgs().hasArg(options::OPT__version)) {
      // Follow gcc behavior and use stdout for --version and stderr for -v.
      PrintVersion(C, llvm::outs());
      return false;
    }
  
    if (C.getArgs().hasArg(options::OPT_v) ||
        C.getArgs().hasArg(options::OPT__HASH_HASH_HASH)) {
      PrintVersion(C, llvm::errs());
      SuppressMissingInputWarning = true;
    }
  
    const ToolChain &TC = C.getDefaultToolChain();
  
    if (C.getArgs().hasArg(options::OPT_v))
      TC.printVerboseInfo(llvm::errs());
  
    if (C.getArgs().hasArg(options::OPT_print_search_dirs)) {
      llvm::outs() << "programs: =";
      for (ToolChain::path_list::const_iterator it = TC.getProgramPaths().begin(),
             ie = TC.getProgramPaths().end(); it != ie; ++it) {
        if (it != TC.getProgramPaths().begin())
          llvm::outs() << ':';
        llvm::outs() << *it;
      }
      llvm::outs() << "\n";
      llvm::outs() << "libraries: =" << ResourceDir;
  
      StringRef sysroot = C.getSysRoot();
  
      for (ToolChain::path_list::const_iterator it = TC.getFilePaths().begin(),
             ie = TC.getFilePaths().end(); it != ie; ++it) {
        llvm::outs() << ':';
        const char *path = it->c_str();
        if (path[0] == '=')
          llvm::outs() << sysroot << path + 1;
        else
          llvm::outs() << path;
      }
      llvm::outs() << "\n";
      return false;
    }
  
    // FIXME: The following handlers should use a callback mechanism, we don't
    // know what the client would like to do.
    if (Arg *A = C.getArgs().getLastArg(options::OPT_print_file_name_EQ)) {
      llvm::outs() << GetFilePath(A->getValue(), TC) << "\n";
      return false;
    }
  
    if (Arg *A = C.getArgs().getLastArg(options::OPT_print_prog_name_EQ)) {
      llvm::outs() << GetProgramPath(A->getValue(), TC) << "\n";
      return false;
    }
  
    if (C.getArgs().hasArg(options::OPT_print_libgcc_file_name)) {
      llvm::outs() << GetFilePath("libgcc.a", TC) << "\n";
      return false;
    }
  
    if (C.getArgs().hasArg(options::OPT_print_multi_lib)) {
      const MultilibSet &Multilibs = TC.getMultilibs();
  
      for (MultilibSet::const_iterator I = Multilibs.begin(), E = Multilibs.end();
           I != E; ++I) {
        llvm::outs() << *I << "\n";
      }
      return false;
    }
  
    if (C.getArgs().hasArg(options::OPT_print_multi_directory)) {
      const MultilibSet &Multilibs = TC.getMultilibs();
      for (MultilibSet::const_iterator I = Multilibs.begin(), E = Multilibs.end();
           I != E; ++I) {
        if (I->gccSuffix().empty())
          llvm::outs() << ".\n";
        else {
          StringRef Suffix(I->gccSuffix());
          assert(Suffix.front() == '/');
          llvm::outs() << Suffix.substr(1) << "\n";
        }
      }
      return false;
    }
  
    if (C.getArgs().hasArg(options::OPT_print_multi_os_directory)) {
      // FIXME: This should print out "lib/../lib", "lib/../lib64", or
      // "lib/../lib32" as appropriate for the toolchain. For now, print
      // nothing because it's not supported yet.
      return false;
    }
  
    return true;
  }
  
  static unsigned PrintActions1(const Compilation &C, Action *A,
                                std::map<Action*, unsigned> &Ids) {
    if (Ids.count(A))
      return Ids[A];
  
    std::string str;
    llvm::raw_string_ostream os(str);
  
    os << Action::getClassName(A->getKind()) << ", ";
    if (InputAction *IA = dyn_cast<InputAction>(A)) {
      os << "\"" << IA->getInputArg().getValue() << "\"";
    } else if (BindArchAction *BIA = dyn_cast<BindArchAction>(A)) {
      os << '"' << BIA->getArchName() << '"'
         << ", {" << PrintActions1(C, *BIA->begin(), Ids) << "}";
    } else {
      os << "{";
      for (Action::iterator it = A->begin(), ie = A->end(); it != ie;) {
        os << PrintActions1(C, *it, Ids);
        ++it;
        if (it != ie)
          os << ", ";
      }
      os << "}";
    }
  
    unsigned Id = Ids.size();
    Ids[A] = Id;
    llvm::errs() << Id << ": " << os.str() << ", "
                 << types::getTypeName(A->getType()) << "\n";
  
    return Id;
  }
  
  void Driver::PrintActions(const Compilation &C) const {
    std::map<Action*, unsigned> Ids;
    for (ActionList::const_iterator it = C.getActions().begin(),
           ie = C.getActions().end(); it != ie; ++it)
      PrintActions1(C, *it, Ids);
  }
  
  /// \brief Check whether the given input tree contains any compilation or
  /// assembly actions.
  static bool ContainsCompileOrAssembleAction(const Action *A) {
    if (isa<CompileJobAction>(A) || isa<AssembleJobAction>(A))
      return true;
  
    for (Action::const_iterator it = A->begin(), ie = A->end(); it != ie; ++it)
      if (ContainsCompileOrAssembleAction(*it))
        return true;
  
    return false;
  }
  
  void Driver::BuildUniversalActions(const ToolChain &TC,
                                     DerivedArgList &Args,
                                     const InputList &BAInputs,
                                     ActionList &Actions) const {
    llvm::PrettyStackTraceString CrashInfo("Building universal build actions");
    // Collect the list of architectures. Duplicates are allowed, but should only
    // be handled once (in the order seen).
    llvm::StringSet<> ArchNames;
    SmallVector<const char *, 4> Archs;
    for (ArgList::const_iterator it = Args.begin(), ie = Args.end();
         it != ie; ++it) {
      Arg *A = *it;
  
      if (A->getOption().matches(options::OPT_arch)) {
        // Validate the option here; we don't save the type here because its
        // particular spelling may participate in other driver choices.
        llvm::Triple::ArchType Arch =
          tools::darwin::getArchTypeForMachOArchName(A->getValue());
        if (Arch == llvm::Triple::UnknownArch) {
          Diag(clang::diag::err_drv_invalid_arch_name)
            << A->getAsString(Args);
          continue;
        }
  
        A->claim();
        if (ArchNames.insert(A->getValue()).second)
          Archs.push_back(A->getValue());
      }
    }
  
    // When there is no explicit arch for this platform, make sure we still bind
    // the architecture (to the default) so that -Xarch_ is handled correctly.
    if (!Archs.size())
      Archs.push_back(Args.MakeArgString(TC.getDefaultUniversalArchName()));
  
    ActionList SingleActions;
    BuildActions(TC, Args, BAInputs, SingleActions);
  
    // Add in arch bindings for every top level action, as well as lipo and
    // dsymutil steps if needed.
    for (unsigned i = 0, e = SingleActions.size(); i != e; ++i) {
      Action *Act = SingleActions[i];
  
      // Make sure we can lipo this kind of output. If not (and it is an actual
      // output) then we disallow, since we can't create an output file with the
      // right name without overwriting it. We could remove this oddity by just
      // changing the output names to include the arch, which would also fix
      // -save-temps. Compatibility wins for now.
  
      if (Archs.size() > 1 && !types::canLipoType(Act->getType()))
        Diag(clang::diag::err_drv_invalid_output_with_multiple_archs)
          << types::getTypeName(Act->getType());
  
      ActionList Inputs;
      for (unsigned i = 0, e = Archs.size(); i != e; ++i) {
        Inputs.push_back(
            new BindArchAction(std::unique_ptr<Action>(Act), Archs[i]));
        if (i != 0)
          Inputs.back()->setOwnsInputs(false);
      }
  
      // Lipo if necessary, we do it this way because we need to set the arch flag
      // so that -Xarch_ gets overwritten.
      if (Inputs.size() == 1 || Act->getType() == types::TY_Nothing)
        Actions.append(Inputs.begin(), Inputs.end());
      else
        Actions.push_back(new LipoJobAction(Inputs, Act->getType()));
  
      // Handle debug info queries.
      Arg *A = Args.getLastArg(options::OPT_g_Group);
      if (A && !A->getOption().matches(options::OPT_g0) &&
          !A->getOption().matches(options::OPT_gstabs) &&
          ContainsCompileOrAssembleAction(Actions.back())) {
  
        // Add a 'dsymutil' step if necessary, when debug info is enabled and we
        // have a compile input. We need to run 'dsymutil' ourselves in such cases
        // because the debug info will refer to a temporary object file which
        // will be removed at the end of the compilation process.
        if (Act->getType() == types::TY_Image) {
          ActionList Inputs;
          Inputs.push_back(Actions.back());
          Actions.pop_back();
          Actions.push_back(new DsymutilJobAction(Inputs, types::TY_dSYM));
        }
  
        // Verify the debug info output.
        if (Args.hasArg(options::OPT_verify_debug_info)) {
          std::unique_ptr<Action> VerifyInput(Actions.back());
          Actions.pop_back();
          Actions.push_back(new VerifyDebugInfoJobAction(std::move(VerifyInput),
                                                         types::TY_Nothing));
        }
      }
    }
  }
  
  /// \brief Check that the file referenced by Value exists. If it doesn't,
  /// issue a diagnostic and return false.
  static bool DiagnoseInputExistence(const Driver &D, const DerivedArgList &Args,
                                     StringRef Value) {
    if (!D.getCheckInputsExist())
      return true;
  
    // stdin always exists.
    if (Value == "-")
      return true;
  
    SmallString<64> Path(Value);
    if (Arg *WorkDir = Args.getLastArg(options::OPT_working_directory)) {
      if (!llvm::sys::path::is_absolute(Path.str())) {
        SmallString<64> Directory(WorkDir->getValue());
        llvm::sys::path::append(Directory, Value);
        Path.assign(Directory);
      }
    }
  
    if (llvm::sys::fs::exists(Twine(Path)))
      return true;
  
    if (D.IsCLMode() && llvm::sys::Process::FindInEnvPath("LIB", Value))
      return true;
  
    D.Diag(clang::diag::err_drv_no_such_file) << Path.str();
    return false;
  }
  
  // Construct a the list of inputs and their types.
  void Driver::BuildInputs(const ToolChain &TC, DerivedArgList &Args,
                           InputList &Inputs) const {
    // Track the current user specified (-x) input. We also explicitly track the
    // argument used to set the type; we only want to claim the type when we
    // actually use it, so we warn about unused -x arguments.
    types::ID InputType = types::TY_Nothing;
    Arg *InputTypeArg = nullptr;
  
    // The last /TC or /TP option sets the input type to C or C++ globally.
    if (Arg *TCTP = Args.getLastArgNoClaim(options::OPT__SLASH_TC,
                                           options::OPT__SLASH_TP)) {
      InputTypeArg = TCTP;
      InputType = TCTP->getOption().matches(options::OPT__SLASH_TC)
          ? types::TY_C : types::TY_CXX;
  
      arg_iterator it = Args.filtered_begin(options::OPT__SLASH_TC,
                                            options::OPT__SLASH_TP);
      const arg_iterator ie = Args.filtered_end();
      Arg *Previous = *it++;
      bool ShowNote = false;
      while (it != ie) {
        Diag(clang::diag::warn_drv_overriding_flag_option)
            << Previous->getSpelling() << (*it)->getSpelling();
        Previous = *it++;
        ShowNote = true;
      }
      if (ShowNote)
        Diag(clang::diag::note_drv_t_option_is_global);
  
      // No driver mode exposes -x and /TC or /TP; we don't support mixing them.
      assert(!Args.hasArg(options::OPT_x) && "-x and /TC or /TP is not allowed");
    }
  
    for (ArgList::const_iterator it = Args.begin(), ie = Args.end();
         it != ie; ++it) {
      Arg *A = *it;
  
      if (A->getOption().getKind() == Option::InputClass) {
        const char *Value = A->getValue();
        types::ID Ty = types::TY_INVALID;
  
        // Infer the input type if necessary.
        if (InputType == types::TY_Nothing) {
          // If there was an explicit arg for this, claim it.
          if (InputTypeArg)
            InputTypeArg->claim();
  
          // stdin must be handled specially.
          if (memcmp(Value, "-", 2) == 0) {
            // If running with -E, treat as a C input (this changes the builtin
            // macros, for example). This may be overridden by -ObjC below.
            //
            // Otherwise emit an error but still use a valid type to avoid
            // spurious errors (e.g., no inputs).
            if (!Args.hasArgNoClaim(options::OPT_E) && !CCCIsCPP())
              Diag(IsCLMode() ? clang::diag::err_drv_unknown_stdin_type_clang_cl
                              : clang::diag::err_drv_unknown_stdin_type);
            Ty = types::TY_C;
          } else {
            // Otherwise lookup by extension.
            // Fallback is C if invoked as C preprocessor or Object otherwise.
            // We use a host hook here because Darwin at least has its own
            // idea of what .s is.
            if (const char *Ext = strrchr(Value, '.'))
              Ty = TC.LookupTypeForExtension(Ext + 1);
  
            if (Ty == types::TY_INVALID) {
              if (CCCIsCPP())
                Ty = types::TY_C;
              else
                Ty = types::TY_Object;
            }
  
            // If the driver is invoked as C++ compiler (like clang++ or c++) it
            // should autodetect some input files as C++ for g++ compatibility.
            if (CCCIsCXX()) {
              types::ID OldTy = Ty;
              Ty = types::lookupCXXTypeForCType(Ty);
  
              if (Ty != OldTy)
                Diag(clang::diag::warn_drv_treating_input_as_cxx)
                  << getTypeName(OldTy) << getTypeName(Ty);
            }
          }
  
          // -ObjC and -ObjC++ override the default language, but only for "source
          // files". We just treat everything that isn't a linker input as a
          // source file.
          //
          // FIXME: Clean this up if we move the phase sequence into the type.
          if (Ty != types::TY_Object) {
            if (Args.hasArg(options::OPT_ObjC))
              Ty = types::TY_ObjC;
            else if (Args.hasArg(options::OPT_ObjCXX))
              Ty = types::TY_ObjCXX;
          }
        } else {
          assert(InputTypeArg && "InputType set w/o InputTypeArg");
          if (!InputTypeArg->getOption().matches(options::OPT_x)) {
            // If emulating cl.exe, make sure that /TC and /TP don't affect input
            // object files.
            const char *Ext = strrchr(Value, '.');
            if (Ext && TC.LookupTypeForExtension(Ext + 1) == types::TY_Object)
              Ty = types::TY_Object;
          }
          if (Ty == types::TY_INVALID) {
            Ty = InputType;
            InputTypeArg->claim();
          }
        }
  
        if (DiagnoseInputExistence(*this, Args, Value))
          Inputs.push_back(std::make_pair(Ty, A));
  
      } else if (A->getOption().matches(options::OPT__SLASH_Tc)) {
        StringRef Value = A->getValue();
        if (DiagnoseInputExistence(*this, Args, Value)) {
          Arg *InputArg = MakeInputArg(Args, Opts, A->getValue());
          Inputs.push_back(std::make_pair(types::TY_C, InputArg));
        }
        A->claim();
      } else if (A->getOption().matches(options::OPT__SLASH_Tp)) {
        StringRef Value = A->getValue();
        if (DiagnoseInputExistence(*this, Args, Value)) {
          Arg *InputArg = MakeInputArg(Args, Opts, A->getValue());
          Inputs.push_back(std::make_pair(types::TY_CXX, InputArg));
        }
        A->claim();
      } else if (A->getOption().hasFlag(options::LinkerInput)) {
        // Just treat as object type, we could make a special type for this if
        // necessary.
        Inputs.push_back(std::make_pair(types::TY_Object, A));
  
      } else if (A->getOption().matches(options::OPT_x)) {
        InputTypeArg = A;
        InputType = types::lookupTypeForTypeSpecifier(A->getValue());
        A->claim();
  
        // Follow gcc behavior and treat as linker input for invalid -x
        // options. Its not clear why we shouldn't just revert to unknown; but
        // this isn't very important, we might as well be bug compatible.
        if (!InputType) {
          Diag(clang::diag::err_drv_unknown_language) << A->getValue();
          InputType = types::TY_Object;
        }
      }
    }
    if (CCCIsCPP() && Inputs.empty()) {
      // If called as standalone preprocessor, stdin is processed
      // if no other input is present.
      Arg *A = MakeInputArg(Args, Opts, "-");
      Inputs.push_back(std::make_pair(types::TY_C, A));
    }
  }
  
  void Driver::BuildActions(const ToolChain &TC, DerivedArgList &Args,
                            const InputList &Inputs, ActionList &Actions) const {
    llvm::PrettyStackTraceString CrashInfo("Building compilation actions");
  
    if (!SuppressMissingInputWarning && Inputs.empty()) {
      Diag(clang::diag::err_drv_no_input_files);
      return;
    }
  
    Arg *FinalPhaseArg;
    phases::ID FinalPhase = getFinalPhase(Args, &FinalPhaseArg);
  
    if (FinalPhase == phases::Link && Args.hasArg(options::OPT_emit_llvm)) {
      Diag(clang::diag::err_drv_emit_llvm_link);
    }
  
    // Reject -Z* at the top level, these options should never have been exposed
    // by gcc.
    if (Arg *A = Args.getLastArg(options::OPT_Z_Joined))
      Diag(clang::diag::err_drv_use_of_Z_option) << A->getAsString(Args);
  
    // Diagnose misuse of /Fo.
    if (Arg *A = Args.getLastArg(options::OPT__SLASH_Fo)) {
      StringRef V = A->getValue();
      if (Inputs.size() > 1 && !V.empty() &&
          !llvm::sys::path::is_separator(V.back())) {
        // Check whether /Fo tries to name an output file for multiple inputs.
        Diag(clang::diag::err_drv_out_file_argument_with_multiple_sources)
          << A->getSpelling() << V;
        Args.eraseArg(options::OPT__SLASH_Fo);
      }
    }
  
    // Diagnose misuse of /Fa.
    if (Arg *A = Args.getLastArg(options::OPT__SLASH_Fa)) {
      StringRef V = A->getValue();
      if (Inputs.size() > 1 && !V.empty() &&
          !llvm::sys::path::is_separator(V.back())) {
        // Check whether /Fa tries to name an asm file for multiple inputs.
        Diag(clang::diag::err_drv_out_file_argument_with_multiple_sources)
          << A->getSpelling() << V;
        Args.eraseArg(options::OPT__SLASH_Fa);
      }
    }
  
    // Diagnose misuse of /o.
    if (Arg *A = Args.getLastArg(options::OPT__SLASH_o)) {
      if (A->getValue()[0] == '\0') {
        // It has to have a value.
        Diag(clang::diag::err_drv_missing_argument) << A->getSpelling() << 1;
        Args.eraseArg(options::OPT__SLASH_o);
      }
    }
  
    // Construct the actions to perform.
    ActionList LinkerInputs;
  
    llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases> PL;
    for (unsigned i = 0, e = Inputs.size(); i != e; ++i) {
      types::ID InputType = Inputs[i].first;
      const Arg *InputArg = Inputs[i].second;
  
      PL.clear();
      types::getCompilationPhases(InputType, PL);
  
      // If the first step comes after the final phase we are doing as part of
      // this compilation, warn the user about it.
      phases::ID InitialPhase = PL[0];
      if (InitialPhase > FinalPhase) {
        // Claim here to avoid the more general unused warning.
        InputArg->claim();
  
        // Suppress all unused style warnings with -Qunused-arguments
        if (Args.hasArg(options::OPT_Qunused_arguments))
          continue;
  
        // Special case when final phase determined by binary name, rather than
        // by a command-line argument with a corresponding Arg.
        if (CCCIsCPP())
          Diag(clang::diag::warn_drv_input_file_unused_by_cpp)
            << InputArg->getAsString(Args)
            << getPhaseName(InitialPhase);
        // Special case '-E' warning on a previously preprocessed file to make
        // more sense.
        else if (InitialPhase == phases::Compile &&
                 FinalPhase == phases::Preprocess &&
                 getPreprocessedType(InputType) == types::TY_INVALID)
          Diag(clang::diag::warn_drv_preprocessed_input_file_unused)
            << InputArg->getAsString(Args)
            << !!FinalPhaseArg
            << (FinalPhaseArg ? FinalPhaseArg->getOption().getName() : "");
        else
          Diag(clang::diag::warn_drv_input_file_unused)
            << InputArg->getAsString(Args)
            << getPhaseName(InitialPhase)
            << !!FinalPhaseArg
            << (FinalPhaseArg ? FinalPhaseArg->getOption().getName() : "");
        continue;
      }
  
      // Build the pipeline for this file.
      std::unique_ptr<Action> Current(new InputAction(*InputArg, InputType));
      for (SmallVectorImpl<phases::ID>::iterator
             i = PL.begin(), e = PL.end(); i != e; ++i) {
        phases::ID Phase = *i;
  
        // We are done if this step is past what the user requested.
        if (Phase > FinalPhase)
          break;
  
        // Queue linker inputs.
        if (Phase == phases::Link) {
          assert((i + 1) == e && "linking must be final compilation step.");
          LinkerInputs.push_back(Current.release());
          break;
        }
  
        // Some types skip the assembler phase (e.g., llvm-bc), but we can't
        // encode this in the steps because the intermediate type depends on
        // arguments. Just special case here.
        if (Phase == phases::Assemble && Current->getType() != types::TY_PP_Asm)
          continue;
  
        // Otherwise construct the appropriate action.
        Current = ConstructPhaseAction(Args, Phase, std::move(Current));
        if (Current->getType() == types::TY_Nothing)
          break;
      }
  
      // If we ended with something, add to the output list.
      if (Current)
        Actions.push_back(Current.release());
    }
  
    // Add a link action if necessary.
    if (!LinkerInputs.empty())
      Actions.push_back(new LinkJobAction(LinkerInputs, types::TY_Image));
  
    // If we are linking, claim any options which are obviously only used for
    // compilation.
    if (FinalPhase == phases::Link && PL.size() == 1) {
      Args.ClaimAllArgs(options::OPT_CompileOnly_Group);
      Args.ClaimAllArgs(options::OPT_cl_compile_Group);
    }
  
    // Claim ignored clang-cl options.
    Args.ClaimAllArgs(options::OPT_cl_ignored_Group);
  }
  
  std::unique_ptr<Action>
  Driver::ConstructPhaseAction(const ArgList &Args, phases::ID Phase,
                               std::unique_ptr<Action> Input) const {
    llvm::PrettyStackTraceString CrashInfo("Constructing phase actions");
    // Build the appropriate action.
    switch (Phase) {
    case phases::Link: llvm_unreachable("link action invalid here.");
    case phases::Preprocess: {
      types::ID OutputTy;
      // -{M, MM} alter the output type.
      if (Args.hasArg(options::OPT_M, options::OPT_MM)) {
        OutputTy = types::TY_Dependencies;
      } else {
        OutputTy = Input->getType();
        if (!Args.hasFlag(options::OPT_frewrite_includes,
                          options::OPT_fno_rewrite_includes, false) &&
            !CCGenDiagnostics)
          OutputTy = types::getPreprocessedType(OutputTy);
        assert(OutputTy != types::TY_INVALID &&
               "Cannot preprocess this input type!");
      }
      return llvm::make_unique<PreprocessJobAction>(std::move(Input), OutputTy);
    }
    case phases::Precompile: {
      types::ID OutputTy = types::TY_PCH;
      if (Args.hasArg(options::OPT_fsyntax_only)) {
        // Syntax checks should not emit a PCH file
        OutputTy = types::TY_Nothing;
      }
      return llvm::make_unique<PrecompileJobAction>(std::move(Input), OutputTy);
    }
    case phases::Compile: {
      if (Args.hasArg(options::OPT_fsyntax_only))
        return llvm::make_unique<CompileJobAction>(std::move(Input),
                                                   types::TY_Nothing);
      if (Args.hasArg(options::OPT_rewrite_objc))
        return llvm::make_unique<CompileJobAction>(std::move(Input),
                                                   types::TY_RewrittenObjC);
      if (Args.hasArg(options::OPT_rewrite_legacy_objc))
        return llvm::make_unique<CompileJobAction>(std::move(Input),
                                                   types::TY_RewrittenLegacyObjC);
      if (Args.hasArg(options::OPT__analyze, options::OPT__analyze_auto))
        return llvm::make_unique<AnalyzeJobAction>(std::move(Input),
                                                   types::TY_Plist);
      if (Args.hasArg(options::OPT__migrate))
        return llvm::make_unique<MigrateJobAction>(std::move(Input),
                                                   types::TY_Remap);
      if (Args.hasArg(options::OPT_emit_ast))
        return llvm::make_unique<CompileJobAction>(std::move(Input),
                                                   types::TY_AST);
      if (Args.hasArg(options::OPT_module_file_info))
        return llvm::make_unique<CompileJobAction>(std::move(Input),
                                                   types::TY_ModuleFile);
      if (Args.hasArg(options::OPT_verify_pch))
        return llvm::make_unique<VerifyPCHJobAction>(std::move(Input),
                                                     types::TY_Nothing);
      if (IsUsingLTO(Args)) {
        types::ID Output =
          Args.hasArg(options::OPT_S) ? types::TY_LTO_IR : types::TY_LTO_BC;
        return llvm::make_unique<CompileJobAction>(std::move(Input), Output);
      }
      if (Args.hasArg(options::OPT_emit_llvm)) {
        types::ID Output =
          Args.hasArg(options::OPT_S) ? types::TY_LLVM_IR : types::TY_LLVM_BC;
        return llvm::make_unique<CompileJobAction>(std::move(Input), Output);
      }
      return llvm::make_unique<CompileJobAction>(std::move(Input),
                                                 types::TY_PP_Asm);
    }
    case phases::Assemble:
      return llvm::make_unique<AssembleJobAction>(std::move(Input),
                                                  types::TY_Object);
    }
  
    llvm_unreachable("invalid phase in ConstructPhaseAction");
  }
  
  bool Driver::IsUsingLTO(const ArgList &Args) const {
    if (Args.hasFlag(options::OPT_flto, options::OPT_fno_lto, false))
      return true;
  
    return false;
  }
  
  void Driver::BuildJobs(Compilation &C) const {
    llvm::PrettyStackTraceString CrashInfo("Building compilation jobs");
  
    Arg *FinalOutput = C.getArgs().getLastArg(options::OPT_o);
  
    // It is an error to provide a -o option if we are making multiple output
    // files.
    if (FinalOutput) {
      unsigned NumOutputs = 0;
      for (ActionList::const_iterator it = C.getActions().begin(),
             ie = C.getActions().end(); it != ie; ++it)
        if ((*it)->getType() != types::TY_Nothing)
          ++NumOutputs;
  
      if (NumOutputs > 1) {
        Diag(clang::diag::err_drv_output_argument_with_multiple_files);
        FinalOutput = nullptr;
      }
    }
  
    // Collect the list of architectures.
    llvm::StringSet<> ArchNames;
    if (C.getDefaultToolChain().getTriple().isOSBinFormatMachO()) {
      for (ArgList::const_iterator it = C.getArgs().begin(), ie = C.getArgs().end();
           it != ie; ++it) {
        Arg *A = *it;
        if (A->getOption().matches(options::OPT_arch))
          ArchNames.insert(A->getValue());
      }
    }
  
    for (ActionList::const_iterator it = C.getActions().begin(),
           ie = C.getActions().end(); it != ie; ++it) {
      Action *A = *it;
  
      // If we are linking an image for multiple archs then the linker wants
      // -arch_multiple and -final_output <final image name>. Unfortunately, this
      // doesn't fit in cleanly because we have to pass this information down.
      //
      // FIXME: This is a hack; find a cleaner way to integrate this into the
      // process.
      const char *LinkingOutput = nullptr;
      if (isa<LipoJobAction>(A)) {
        if (FinalOutput)
          LinkingOutput = FinalOutput->getValue();
        else
          LinkingOutput = DefaultImageName.c_str();
      }
  
      InputInfo II;
      BuildJobsForAction(C, A, &C.getDefaultToolChain(),
                         /*BoundArch*/nullptr,
                         /*AtTopLevel*/ true,
                         /*MultipleArchs*/ ArchNames.size() > 1,
                         /*LinkingOutput*/ LinkingOutput,
                         II);
    }
  
    // If the user passed -Qunused-arguments or there were errors, don't warn
    // about any unused arguments.
    if (Diags.hasErrorOccurred() ||
        C.getArgs().hasArg(options::OPT_Qunused_arguments))
      return;
  
    // Claim -### here.
    (void) C.getArgs().hasArg(options::OPT__HASH_HASH_HASH);
  
    // Claim --driver-mode, it was handled earlier.
    (void) C.getArgs().hasArg(options::OPT_driver_mode);
  
    for (ArgList::const_iterator it = C.getArgs().begin(), ie = C.getArgs().end();
         it != ie; ++it) {
      Arg *A = *it;
  
      // FIXME: It would be nice to be able to send the argument to the
      // DiagnosticsEngine, so that extra values, position, and so on could be
      // printed.
      if (!A->isClaimed()) {
        if (A->getOption().hasFlag(options::NoArgumentUnused))
          continue;
  
        // Suppress the warning automatically if this is just a flag, and it is an
        // instance of an argument we already claimed.
        const Option &Opt = A->getOption();
        if (Opt.getKind() == Option::FlagClass) {
          bool DuplicateClaimed = false;
  
          for (arg_iterator it = C.getArgs().filtered_begin(&Opt),
                 ie = C.getArgs().filtered_end(); it != ie; ++it) {
            if ((*it)->isClaimed()) {
              DuplicateClaimed = true;
              break;
            }
          }
  
          if (DuplicateClaimed)
            continue;
        }
  
        Diag(clang::diag::warn_drv_unused_argument)
          << A->getAsString(C.getArgs());
      }
    }
  }
  
  static const Tool *SelectToolForJob(Compilation &C, const ToolChain *TC,
                                      const JobAction *JA,
                                      const ActionList *&Inputs) {
    const Tool *ToolForJob = nullptr;
  
    // See if we should look for a compiler with an integrated assembler. We match
    // bottom up, so what we are actually looking for is an assembler job with a
    // compiler input.
  
    if (TC->useIntegratedAs() &&
        !C.getArgs().hasArg(options::OPT_save_temps) &&
        !C.getArgs().hasArg(options::OPT_via_file_asm) &&
        !C.getArgs().hasArg(options::OPT__SLASH_FA) &&
        !C.getArgs().hasArg(options::OPT__SLASH_Fa) &&
        isa<AssembleJobAction>(JA) &&
        Inputs->size() == 1 && isa<CompileJobAction>(*Inputs->begin())) {
      const Tool *Compiler =
        TC->SelectTool(cast<JobAction>(**Inputs->begin()));
      if (!Compiler)
        return nullptr;
      if (Compiler->hasIntegratedAssembler()) {
        Inputs = &(*Inputs)[0]->getInputs();
        ToolForJob = Compiler;
      }
    }
  
    // Otherwise use the tool for the current job.
    if (!ToolForJob)
      ToolForJob = TC->SelectTool(*JA);
  
    // See if we should use an integrated preprocessor. We do so when we have
    // exactly one input, since this is the only use case we care about
    // (irrelevant since we don't support combine yet).
    if (Inputs->size() == 1 && isa<PreprocessJobAction>(*Inputs->begin()) &&
        !C.getArgs().hasArg(options::OPT_no_integrated_cpp) &&
        !C.getArgs().hasArg(options::OPT_traditional_cpp) &&
        !C.getArgs().hasArg(options::OPT_save_temps) &&
        !C.getArgs().hasArg(options::OPT_rewrite_objc) &&
        ToolForJob->hasIntegratedCPP())
      Inputs = &(*Inputs)[0]->getInputs();
  
    return ToolForJob;
  }
  
  void Driver::BuildJobsForAction(Compilation &C,
                                  const Action *A,
                                  const ToolChain *TC,
                                  const char *BoundArch,
                                  bool AtTopLevel,
                                  bool MultipleArchs,
                                  const char *LinkingOutput,
                                  InputInfo &Result) const {
    llvm::PrettyStackTraceString CrashInfo("Building compilation jobs");
  
    if (const InputAction *IA = dyn_cast<InputAction>(A)) {
      // FIXME: It would be nice to not claim this here; maybe the old scheme of
      // just using Args was better?
      const Arg &Input = IA->getInputArg();
      Input.claim();
      if (Input.getOption().matches(options::OPT_INPUT)) {
        const char *Name = Input.getValue();
        Result = InputInfo(Name, A->getType(), Name);
      } else
        Result = InputInfo(&Input, A->getType(), "");
      return;
    }
  
    if (const BindArchAction *BAA = dyn_cast<BindArchAction>(A)) {
      const ToolChain *TC;
      const char *ArchName = BAA->getArchName();
  
      if (ArchName)
        TC = &getToolChain(C.getArgs(), ArchName);
      else
        TC = &C.getDefaultToolChain();
  
      BuildJobsForAction(C, *BAA->begin(), TC, BAA->getArchName(),
                         AtTopLevel, MultipleArchs, LinkingOutput, Result);
      return;
    }
  
    const ActionList *Inputs = &A->getInputs();
  
    const JobAction *JA = cast<JobAction>(A);
    const Tool *T = SelectToolForJob(C, TC, JA, Inputs);
    if (!T)
      return;
  
    // Only use pipes when there is exactly one input.
    InputInfoList InputInfos;
    for (ActionList::const_iterator it = Inputs->begin(), ie = Inputs->end();
         it != ie; ++it) {
      // Treat dsymutil and verify sub-jobs as being at the top-level too, they
      // shouldn't get temporary output names.
      // FIXME: Clean this up.
      bool SubJobAtTopLevel = false;
      if (AtTopLevel && (isa<DsymutilJobAction>(A) || isa<VerifyJobAction>(A)))
        SubJobAtTopLevel = true;
  
      InputInfo II;
      BuildJobsForAction(C, *it, TC, BoundArch, SubJobAtTopLevel, MultipleArchs,
                         LinkingOutput, II);
      InputInfos.push_back(II);
    }
  
    // Always use the first input as the base input.
    const char *BaseInput = InputInfos[0].getBaseInput();
  
    // ... except dsymutil actions, which use their actual input as the base
    // input.
    if (JA->getType() == types::TY_dSYM)
      BaseInput = InputInfos[0].getFilename();
  
    // Determine the place to write output to, if any.
    if (JA->getType() == types::TY_Nothing)
      Result = InputInfo(A->getType(), BaseInput);
    else
      Result = InputInfo(GetNamedOutputPath(C, *JA, BaseInput, BoundArch,
                                            AtTopLevel, MultipleArchs),
                         A->getType(), BaseInput);
  
    if (CCCPrintBindings && !CCGenDiagnostics) {
      llvm::errs() << "# \"" << T->getToolChain().getTripleString() << '"'
                   << " - \"" << T->getName() << "\", inputs: [";
      for (unsigned i = 0, e = InputInfos.size(); i != e; ++i) {
        llvm::errs() << InputInfos[i].getAsString();
        if (i + 1 != e)
          llvm::errs() << ", ";
      }
      llvm::errs() << "], output: " << Result.getAsString() << "\n";
    } else {
      T->ConstructJob(C, *JA, Result, InputInfos,
                      C.getArgsForToolChain(TC, BoundArch), LinkingOutput);
    }
  }
  
  /// \brief Create output filename based on ArgValue, which could either be a
  /// full filename, filename without extension, or a directory. If ArgValue
  /// does not provide a filename, then use BaseName, and use the extension
  /// suitable for FileType.
  static const char *MakeCLOutputFilename(const ArgList &Args, StringRef ArgValue,
                                          StringRef BaseName, types::ID FileType) {
    SmallString<128> Filename = ArgValue;
  
    if (ArgValue.empty()) {
      // If the argument is empty, output to BaseName in the current dir.
      Filename = BaseName;
    } else if (llvm::sys::path::is_separator(Filename.back())) {
      // If the argument is a directory, output to BaseName in that dir.
      llvm::sys::path::append(Filename, BaseName);
    }
  
    if (!llvm::sys::path::has_extension(ArgValue)) {
      // If the argument didn't provide an extension, then set it.
      const char *Extension = types::getTypeTempSuffix(FileType, true);
  
      if (FileType == types::TY_Image &&
          Args.hasArg(options::OPT__SLASH_LD, options::OPT__SLASH_LDd)) {
        // The output file is a dll.
        Extension = "dll";
      }
  
      llvm::sys::path::replace_extension(Filename, Extension);
    }
  
    return Args.MakeArgString(Filename.c_str());
  }
  
  const char *Driver::GetNamedOutputPath(Compilation &C,
                                         const JobAction &JA,
                                         const char *BaseInput,
                                         const char *BoundArch,
                                         bool AtTopLevel,
                                         bool MultipleArchs) const {
    llvm::PrettyStackTraceString CrashInfo("Computing output path");
    // Output to a user requested destination?
    if (AtTopLevel && !isa<DsymutilJobAction>(JA) &&
        !isa<VerifyJobAction>(JA)) {
      if (Arg *FinalOutput = C.getArgs().getLastArg(options::OPT_o))
        return C.addResultFile(FinalOutput->getValue(), &JA);
    }
  
    // For /P, preprocess to file named after BaseInput.
    if (C.getArgs().hasArg(options::OPT__SLASH_P)) {
      assert(AtTopLevel && isa<PreprocessJobAction>(JA));
      StringRef BaseName = llvm::sys::path::filename(BaseInput);
      StringRef NameArg;
      if (Arg *A = C.getArgs().getLastArg(options::OPT__SLASH_Fi,
                                          options::OPT__SLASH_o))
        NameArg = A->getValue();
      return C.addResultFile(MakeCLOutputFilename(C.getArgs(), NameArg, BaseName,
                                                  types::TY_PP_C), &JA);
    }
  
    // Default to writing to stdout?
    if (AtTopLevel && !CCGenDiagnostics &&
        (isa<PreprocessJobAction>(JA) || JA.getType() == types::TY_ModuleFile))
      return "-";
  
    // Is this the assembly listing for /FA?
    if (JA.getType() == types::TY_PP_Asm &&
        (C.getArgs().hasArg(options::OPT__SLASH_FA) ||
         C.getArgs().hasArg(options::OPT__SLASH_Fa))) {
      // Use /Fa and the input filename to determine the asm file name.
      StringRef BaseName = llvm::sys::path::filename(BaseInput);
      StringRef FaValue = C.getArgs().getLastArgValue(options::OPT__SLASH_Fa);
      return C.addResultFile(MakeCLOutputFilename(C.getArgs(), FaValue, BaseName,
                                                  JA.getType()), &JA);
    }
  
    // Output to a temporary file?
    if ((!AtTopLevel && !C.getArgs().hasArg(options::OPT_save_temps) &&
          !C.getArgs().hasArg(options::OPT__SLASH_Fo)) ||
        CCGenDiagnostics) {
      StringRef Name = llvm::sys::path::filename(BaseInput);
      std::pair<StringRef, StringRef> Split = Name.split('.');
      std::string TmpName =
        GetTemporaryPath(Split.first,
            types::getTypeTempSuffix(JA.getType(), IsCLMode()));
      return C.addTempFile(C.getArgs().MakeArgString(TmpName.c_str()));
    }
  
    SmallString<128> BasePath(BaseInput);
    StringRef BaseName;
  
    // Dsymutil actions should use the full path.
    if (isa<DsymutilJobAction>(JA) || isa<VerifyJobAction>(JA))
      BaseName = BasePath;
    else
      BaseName = llvm::sys::path::filename(BasePath);
  
    // Determine what the derived output name should be.
    const char *NamedOutput;
  
    if (JA.getType() == types::TY_Object &&
        C.getArgs().hasArg(options::OPT__SLASH_Fo, options::OPT__SLASH_o)) {
      // The /Fo or /o flag decides the object filename.
      StringRef Val = C.getArgs().getLastArg(options::OPT__SLASH_Fo,
                                             options::OPT__SLASH_o)->getValue();
      NamedOutput = MakeCLOutputFilename(C.getArgs(), Val, BaseName,
                                         types::TY_Object);
    } else if (JA.getType() == types::TY_Image &&
               C.getArgs().hasArg(options::OPT__SLASH_Fe, options::OPT__SLASH_o)) {
      // The /Fe or /o flag names the linked file.
      StringRef Val = C.getArgs().getLastArg(options::OPT__SLASH_Fe,
                                             options::OPT__SLASH_o)->getValue();
      NamedOutput = MakeCLOutputFilename(C.getArgs(), Val, BaseName,
                                         types::TY_Image);
    } else if (JA.getType() == types::TY_Image) {
      if (IsCLMode()) {
        // clang-cl uses BaseName for the executable name.
        NamedOutput = MakeCLOutputFilename(C.getArgs(), "", BaseName,
                                           types::TY_Image);
      } else if (MultipleArchs && BoundArch) {
        SmallString<128> Output(DefaultImageName.c_str());
        Output += "-";
        Output.append(BoundArch);
        NamedOutput = C.getArgs().MakeArgString(Output.c_str());
      } else
        NamedOutput = DefaultImageName.c_str();
    } else {
      const char *Suffix = types::getTypeTempSuffix(JA.getType(), IsCLMode());
      assert(Suffix && "All types used for output should have a suffix.");
  
      std::string::size_type End = std::string::npos;
      if (!types::appendSuffixForType(JA.getType()))
        End = BaseName.rfind('.');
      SmallString<128> Suffixed(BaseName.substr(0, End));
      if (MultipleArchs && BoundArch) {
        Suffixed += "-";
        Suffixed.append(BoundArch);
      }
      Suffixed += '.';
      Suffixed += Suffix;
      NamedOutput = C.getArgs().MakeArgString(Suffixed.c_str());
    }
  
    // If we're saving temps and the temp file conflicts with the input file,
    // then avoid overwriting input file.
    if (!AtTopLevel && C.getArgs().hasArg(options::OPT_save_temps) &&
        NamedOutput == BaseName) {
  
      bool SameFile = false;
      SmallString<256> Result;
      llvm::sys::fs::current_path(Result);
      llvm::sys::path::append(Result, BaseName);
      llvm::sys::fs::equivalent(BaseInput, Result.c_str(), SameFile);
      // Must share the same path to conflict.
      if (SameFile) {
        StringRef Name = llvm::sys::path::filename(BaseInput);
        std::pair<StringRef, StringRef> Split = Name.split('.');
        std::string TmpName =
          GetTemporaryPath(Split.first,
              types::getTypeTempSuffix(JA.getType(), IsCLMode()));
        return C.addTempFile(C.getArgs().MakeArgString(TmpName.c_str()));
      }
    }
  
    // As an annoying special case, PCH generation doesn't strip the pathname.
    if (JA.getType() == types::TY_PCH) {
      llvm::sys::path::remove_filename(BasePath);
      if (BasePath.empty())
        BasePath = NamedOutput;
      else
        llvm::sys::path::append(BasePath, NamedOutput);
      return C.addResultFile(C.getArgs().MakeArgString(BasePath.c_str()), &JA);
    } else {
      return C.addResultFile(NamedOutput, &JA);
    }
  }
  
  std::string Driver::GetFilePath(const char *Name, const ToolChain &TC) const {
    // Respect a limited subset of the '-Bprefix' functionality in GCC by
    // attempting to use this prefix when looking for file paths.
    for (Driver::prefix_list::const_iterator it = PrefixDirs.begin(),
         ie = PrefixDirs.end(); it != ie; ++it) {
      std::string Dir(*it);
      if (Dir.empty())
        continue;
      if (Dir[0] == '=')
        Dir = SysRoot + Dir.substr(1);
      SmallString<128> P(Dir);
      llvm::sys::path::append(P, Name);
      if (llvm::sys::fs::exists(Twine(P)))
        return P.str();
    }
  
    SmallString<128> P(ResourceDir);
    llvm::sys::path::append(P, Name);
    if (llvm::sys::fs::exists(Twine(P)))
      return P.str();
  
    const ToolChain::path_list &List = TC.getFilePaths();
    for (ToolChain::path_list::const_iterator
           it = List.begin(), ie = List.end(); it != ie; ++it) {
      std::string Dir(*it);
      if (Dir.empty())
        continue;
      if (Dir[0] == '=')
        Dir = SysRoot + Dir.substr(1);
      SmallString<128> P(Dir);
      llvm::sys::path::append(P, Name);
      if (llvm::sys::fs::exists(Twine(P)))
        return P.str();
    }
  
    return Name;
  }
  
  void
  Driver::generatePrefixedToolNames(const char *Tool, const ToolChain &TC,
                                    SmallVectorImpl<std::string> &Names) const {
    // FIXME: Needs a better variable than DefaultTargetTriple
    Names.push_back(DefaultTargetTriple + "-" + Tool);
    Names.push_back(Tool);
  }
  
  static bool ScanDirForExecutable(SmallString<128> &Dir,
                                   ArrayRef<std::string> Names) {
    for (const auto &Name : Names) {
      llvm::sys::path::append(Dir, Name);
      if (llvm::sys::fs::can_execute(Twine(Dir)))
        return true;
      llvm::sys::path::remove_filename(Dir);
    }
    return false;
  }
  
  std::string Driver::GetProgramPath(const char *Name,
                                     const ToolChain &TC) const {
    SmallVector<std::string, 2> TargetSpecificExecutables;
    generatePrefixedToolNames(Name, TC, TargetSpecificExecutables);
  
    // Respect a limited subset of the '-Bprefix' functionality in GCC by
    // attempting to use this prefix when looking for program paths.
    for (const auto &PrefixDir : PrefixDirs) {
      if (llvm::sys::fs::is_directory(PrefixDir)) {
        SmallString<128> P(PrefixDir);
        if (ScanDirForExecutable(P, TargetSpecificExecutables))
          return P.str();
      } else {
        SmallString<128> P(PrefixDir + Name);
        if (llvm::sys::fs::can_execute(Twine(P)))
          return P.str();
      }
    }
  
    const ToolChain::path_list &List = TC.getProgramPaths();
    for (const auto &Path : List) {
      SmallString<128> P(Path);
      if (ScanDirForExecutable(P, TargetSpecificExecutables))
        return P.str();
    }
  
    // If all else failed, search the path.
    for (const auto &TargetSpecificExecutable : TargetSpecificExecutables)
      if (llvm::ErrorOr<std::string> P =
              llvm::sys::findProgramByName(TargetSpecificExecutable))
        return *P;
  
    return Name;
  }
  
  std::string Driver::GetTemporaryPath(StringRef Prefix, const char *Suffix)
    const {
    SmallString<128> Path;
    std::error_code EC = llvm::sys::fs::createTemporaryFile(Prefix, Suffix, Path);
    if (EC) {
      Diag(clang::diag::err_unable_to_make_temp) << EC.message();
      return "";
    }
  
    return Path.str();
  }
  
  /// \brief Compute target triple from args.
  ///
  /// This routine provides the logic to compute a target triple from various
  /// args passed to the driver and the default triple string.
  static llvm::Triple computeTargetTriple(StringRef DefaultTargetTriple,
                                          const ArgList &Args,
                                          StringRef DarwinArchName) {
    // FIXME: Already done in Compilation *Driver::BuildCompilation
    if (const Arg *A = Args.getLastArg(options::OPT_target))
      DefaultTargetTriple = A->getValue();
  
    llvm::Triple Target(llvm::Triple::normalize(DefaultTargetTriple));
  
    // Handle Apple-specific options available here.
    if (Target.isOSBinFormatMachO()) {
      // If an explict Darwin arch name is given, that trumps all.
      if (!DarwinArchName.empty()) {
        tools::darwin::setTripleTypeForMachOArchName(Target, DarwinArchName);
        return Target;
      }
  
      // Handle the Darwin '-arch' flag.
      if (Arg *A = Args.getLastArg(options::OPT_arch)) {
        StringRef ArchName = A->getValue();
        tools::darwin::setTripleTypeForMachOArchName(Target, ArchName);
      }
    }
  
    // Handle pseudo-target flags '-mlittle-endian'/'-EL' and
    // '-mbig-endian'/'-EB'.
    if (Arg *A = Args.getLastArg(options::OPT_mlittle_endian,
                                 options::OPT_mbig_endian)) {
      if (A->getOption().matches(options::OPT_mlittle_endian)) {
        if (Target.getArch() == llvm::Triple::mips)
          Target.setArch(llvm::Triple::mipsel);
        else if (Target.getArch() == llvm::Triple::mips64)
          Target.setArch(llvm::Triple::mips64el);
        else if (Target.getArch() == llvm::Triple::aarch64_be)
          Target.setArch(llvm::Triple::aarch64);
      } else {
        if (Target.getArch() == llvm::Triple::mipsel)
          Target.setArch(llvm::Triple::mips);
        else if (Target.getArch() == llvm::Triple::mips64el)
          Target.setArch(llvm::Triple::mips64);
        else if (Target.getArch() == llvm::Triple::aarch64)
          Target.setArch(llvm::Triple::aarch64_be);
      }
    }
  
    // Skip further flag support on OSes which don't support '-m32' or '-m64'.
    if (Target.getArchName() == "tce" || Target.getOS() == llvm::Triple::Minix)
      return Target;
  
    // Handle pseudo-target flags '-m64', '-mx32', '-m32' and '-m16'.
    if (Arg *A = Args.getLastArg(options::OPT_m64, options::OPT_mx32,
                                 options::OPT_m32, options::OPT_m16)) {
      llvm::Triple::ArchType AT = llvm::Triple::UnknownArch;
  
      if (A->getOption().matches(options::OPT_m64)) {
        AT = Target.get64BitArchVariant().getArch();
        if (Target.getEnvironment() == llvm::Triple::GNUX32)
          Target.setEnvironment(llvm::Triple::GNU);
      } else if (A->getOption().matches(options::OPT_mx32) &&
               Target.get64BitArchVariant().getArch() == llvm::Triple::x86_64) {
        AT = llvm::Triple::x86_64;
        Target.setEnvironment(llvm::Triple::GNUX32);
      } else if (A->getOption().matches(options::OPT_m32)) {
        AT = Target.get32BitArchVariant().getArch();
        if (Target.getEnvironment() == llvm::Triple::GNUX32)
          Target.setEnvironment(llvm::Triple::GNU);
      } else if (A->getOption().matches(options::OPT_m16) &&
               Target.get32BitArchVariant().getArch() == llvm::Triple::x86) {
        AT = llvm::Triple::x86;
        Target.setEnvironment(llvm::Triple::CODE16);
      }
  
      if (AT != llvm::Triple::UnknownArch && AT != Target.getArch())
        Target.setArch(AT);
    }
  
    return Target;
  }
  
  const ToolChain &Driver::getToolChain(const ArgList &Args,
                                        StringRef DarwinArchName) const {
    llvm::Triple Target = computeTargetTriple(DefaultTargetTriple, Args,
                                              DarwinArchName);
  
    ToolChain *&TC = ToolChains[Target.str()];
    if (!TC) {
      switch (Target.getOS()) {
      case llvm::Triple::Darwin:
      case llvm::Triple::MacOSX:
      case llvm::Triple::IOS:
        TC = new toolchains::DarwinClang(*this, Target, Args);
        break;
      case llvm::Triple::DragonFly:
        TC = new toolchains::DragonFly(*this, Target, Args);
        break;
      case llvm::Triple::OpenBSD:
        TC = new toolchains::OpenBSD(*this, Target, Args);
        break;
      case llvm::Triple::Bitrig:
        TC = new toolchains::Bitrig(*this, Target, Args);
        break;
      case llvm::Triple::NetBSD:
        TC = new toolchains::NetBSD(*this, Target, Args);
        break;
      case llvm::Triple::FreeBSD:
        TC = new toolchains::FreeBSD(*this, Target, Args);
        break;
      case llvm::Triple::Minix:
        TC = new toolchains::Minix(*this, Target, Args);
        break;
      case llvm::Triple::Linux:
        if (Target.getArch() == llvm::Triple::hexagon)
          TC = new toolchains::Hexagon_TC(*this, Target, Args);
        else
          TC = new toolchains::Linux(*this, Target, Args);
        break;
      case llvm::Triple::Solaris:
        TC = new toolchains::Solaris(*this, Target, Args);
        break;
      case llvm::Triple::Win32:
        switch (Target.getEnvironment()) {
        default:
          if (Target.isOSBinFormatELF())
            TC = new toolchains::Generic_ELF(*this, Target, Args);
          else if (Target.isOSBinFormatMachO())
            TC = new toolchains::MachO(*this, Target, Args);
          else
            TC = new toolchains::Generic_GCC(*this, Target, Args);
          break;
        case llvm::Triple::GNU:
          // FIXME: We need a MinGW toolchain.  Use the default Generic_GCC
          // toolchain for now as the default case would below otherwise.
          if (Target.isOSBinFormatELF())
            TC = new toolchains::Generic_ELF(*this, Target, Args);
          else
            TC = new toolchains::Generic_GCC(*this, Target, Args);
          break;
        case llvm::Triple::Itanium:
          TC = new toolchains::CrossWindowsToolChain(*this, Target, Args);
          break;
        case llvm::Triple::MSVC:
        case llvm::Triple::UnknownEnvironment:
          TC = new toolchains::MSVCToolChain(*this, Target, Args);
          break;
        }
        break;
      default:
        // TCE is an OSless target
        if (Target.getArchName() == "tce") {
          TC = new toolchains::TCEToolChain(*this, Target, Args);
          break;
        }
        // If Hexagon is configured as an OSless target
        if (Target.getArch() == llvm::Triple::hexagon) {
          TC = new toolchains::Hexagon_TC(*this, Target, Args);
          break;
        }
        if (Target.getArch() == llvm::Triple::xcore) {
          TC = new toolchains::XCore(*this, Target, Args);
          break;
        }
        if (Target.isOSBinFormatELF()) {
          TC = new toolchains::Generic_ELF(*this, Target, Args);
          break;
        }
        if (Target.getObjectFormat() == llvm::Triple::MachO) {
          TC = new toolchains::MachO(*this, Target, Args);
          break;
        }
        TC = new toolchains::Generic_GCC(*this, Target, Args);
        break;
      }
    }
    return *TC;
  }
  
  bool Driver::ShouldUseClangCompiler(const JobAction &JA) const {
    // Check if user requested no clang, or clang doesn't understand this type (we
    // only handle single inputs for now).
    if (JA.size() != 1 ||
        !types::isAcceptedByClang((*JA.begin())->getType()))
      return false;
  
    // Otherwise make sure this is an action clang understands.
    if (!isa<PreprocessJobAction>(JA) && !isa<PrecompileJobAction>(JA) &&
        !isa<CompileJobAction>(JA))
      return false;
  
    return true;
  }
  
  /// GetReleaseVersion - Parse (([0-9]+)(.([0-9]+)(.([0-9]+)?))?)? and return the
  /// grouped values as integers. Numbers which are not provided are set to 0.
  ///
  /// \return True if the entire string was parsed (9.2), or all groups were
  /// parsed (10.3.5extrastuff).
  bool Driver::GetReleaseVersion(const char *Str, unsigned &Major,
                                 unsigned &Minor, unsigned &Micro,
                                 bool &HadExtra) {
    HadExtra = false;
  
    Major = Minor = Micro = 0;
    if (*Str == '\0')
      return true;
  
    char *End;
    Major = (unsigned) strtol(Str, &End, 10);
    if (*Str != '\0' && *End == '\0')
      return true;
    if (*End != '.')
      return false;
  
    Str = End+1;
    Minor = (unsigned) strtol(Str, &End, 10);
    if (*Str != '\0' && *End == '\0')
      return true;
    if (*End != '.')
      return false;
  
    Str = End+1;
    Micro = (unsigned) strtol(Str, &End, 10);
    if (*Str != '\0' && *End == '\0')
      return true;
    if (Str == End)
      return false;
    HadExtra = true;
    return true;
  }
  
  std::pair<unsigned, unsigned> Driver::getIncludeExcludeOptionFlagMasks() const {
    unsigned IncludedFlagsBitmask = 0;
    unsigned ExcludedFlagsBitmask = options::NoDriverOption;
  
    if (Mode == CLMode) {
      // Include CL and Core options.
      IncludedFlagsBitmask |= options::CLOption;
      IncludedFlagsBitmask |= options::CoreOption;
    } else {
      ExcludedFlagsBitmask |= options::CLOption;
    }
  
    return std::make_pair(IncludedFlagsBitmask, ExcludedFlagsBitmask);
  }
  
  bool clang::driver::isOptimizationLevelFast(const llvm::opt::ArgList &Args) {
    return Args.hasFlag(options::OPT_Ofast, options::OPT_O_Group, false);
  }
  