//===--- ToolChains.cpp - ToolChain Implementations -----------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "ToolChains.h"

#ifdef HAVE_CLANG_CONFIG_H
# include "clang/Config/config.h"
#endif

#include "clang/Driver/Arg.h"
#include "clang/Driver/ArgList.h"
#include "clang/Driver/Compilation.h"
#include "clang/Driver/Driver.h"
#include "clang/Driver/DriverDiagnostic.h"
#include "clang/Driver/HostInfo.h"
#include "clang/Driver/ObjCRuntime.h"
#include "clang/Driver/OptTable.h"
#include "clang/Driver/Option.h"
#include "clang/Driver/Options.h"
#include "clang/Basic/Version.h"

#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/system_error.h"

#include <cstdlib> // ::getenv

#include "llvm/Config/config.h" // for CXX_INCLUDE_ROOT

using namespace clang::driver;
using namespace clang::driver::toolchains;
using namespace clang;

/// Darwin - Darwin tool chain for i386 and x86_64.

Darwin::Darwin(const HostInfo &Host, const llvm::Triple& Triple)
  : ToolChain(Host, Triple), TargetInitialized(false),
    ARCRuntimeForSimulator(ARCSimulator_None)
{
  // Compute the initial Darwin version based on the host.
  bool HadExtra;
  std::string OSName = Triple.getOSName();
  if (!Driver::GetReleaseVersion(&OSName.c_str()[6],
                                 DarwinVersion[0], DarwinVersion[1],
                                 DarwinVersion[2], HadExtra))
    getDriver().Diag(diag::err_drv_invalid_darwin_version) << OSName;

  llvm::raw_string_ostream(MacosxVersionMin)
    << "10." << std::max(0, (int)DarwinVersion[0] - 4) << '.'
    << DarwinVersion[1];
}

types::ID Darwin::LookupTypeForExtension(const char *Ext) const {
  types::ID Ty = types::lookupTypeForExtension(Ext);

  // Darwin always preprocesses assembly files (unless -x is used explicitly).
  if (Ty == types::TY_PP_Asm)
    return types::TY_Asm;

  return Ty;
}

bool Darwin::HasNativeLLVMSupport() const {
  return true;
}

bool Darwin::hasARCRuntime() const {
  // FIXME: Remove this once there is a proper way to detect an ARC runtime
  // for the simulator.
  switch (ARCRuntimeForSimulator) {
  case ARCSimulator_None:
    break;
  case ARCSimulator_HasARCRuntime:
    return true;
  case ARCSimulator_NoARCRuntime:
    return false;
  }

  if (isTargetIPhoneOS())
    return !isIPhoneOSVersionLT(5);
  else
    return !isMacosxVersionLT(10, 7);
}

/// Darwin provides an ARC runtime starting in MacOS X 10.7 and iOS 5.0.
void Darwin::configureObjCRuntime(ObjCRuntime &runtime) const {
  if (runtime.getKind() != ObjCRuntime::NeXT)
    return ToolChain::configureObjCRuntime(runtime);

  runtime.HasARC = runtime.HasWeak = hasARCRuntime();

  // So far, objc_terminate is only available in iOS 5.
  // FIXME: do the simulator logic properly.
  if (!ARCRuntimeForSimulator && isTargetIPhoneOS())
    runtime.HasTerminate = !isIPhoneOSVersionLT(5);
  else
    runtime.HasTerminate = false;
}

/// Darwin provides a blocks runtime starting in MacOS X 10.6 and iOS 3.2.
bool Darwin::hasBlocksRuntime() const {
  if (isTargetIPhoneOS())
    return !isIPhoneOSVersionLT(3, 2);
  else
    return !isMacosxVersionLT(10, 6);
}

// FIXME: Can we tablegen this?
static const char *GetArmArchForMArch(StringRef Value) {
  if (Value == "armv6k")
    return "armv6";

  if (Value == "armv5tej")
    return "armv5";

  if (Value == "xscale")
    return "xscale";

  if (Value == "armv4t")
    return "armv4t";

  if (Value == "armv7" || Value == "armv7-a" || Value == "armv7-r" ||
      Value == "armv7-m" || Value == "armv7a" || Value == "armv7r" ||
      Value == "armv7m")
    return "armv7";

  return 0;
}

// FIXME: Can we tablegen this?
static const char *GetArmArchForMCpu(StringRef Value) {
  if (Value == "arm10tdmi" || Value == "arm1020t" || Value == "arm9e" ||
      Value == "arm946e-s" || Value == "arm966e-s" ||
      Value == "arm968e-s" || Value == "arm10e" ||
      Value == "arm1020e" || Value == "arm1022e" || Value == "arm926ej-s" ||
      Value == "arm1026ej-s")
    return "armv5";

  if (Value == "xscale")
    return "xscale";

  if (Value == "arm1136j-s" || Value == "arm1136jf-s" ||
      Value == "arm1176jz-s" || Value == "arm1176jzf-s" ||
      Value == "cortex-m0" )
    return "armv6";

  if (Value == "cortex-a8" || Value == "cortex-r4" || Value == "cortex-m3")
    return "armv7";

  return 0;
}

StringRef Darwin::getDarwinArchName(const ArgList &Args) const {
  switch (getTriple().getArch()) {
  default:
    return getArchName();

  case llvm::Triple::thumb:
  case llvm::Triple::arm: {
    if (const Arg *A = Args.getLastArg(options::OPT_march_EQ))
      if (const char *Arch = GetArmArchForMArch(A->getValue(Args)))
        return Arch;

    if (const Arg *A = Args.getLastArg(options::OPT_mcpu_EQ))
      if (const char *Arch = GetArmArchForMCpu(A->getValue(Args)))
        return Arch;

    return "arm";
  }
  }
}

Darwin::~Darwin() {
  // Free tool implementations.
  for (llvm::DenseMap<unsigned, Tool*>::iterator
         it = Tools.begin(), ie = Tools.end(); it != ie; ++it)
    delete it->second;
}

std::string Darwin::ComputeEffectiveClangTriple(const ArgList &Args,
                                                types::ID InputType) const {
  llvm::Triple Triple(ComputeLLVMTriple(Args, InputType));

  // If the target isn't initialized (e.g., an unknown Darwin platform, return
  // the default triple).
  if (!isTargetInitialized())
    return Triple.getTriple();

  unsigned Version[3];
  getTargetVersion(Version);

  llvm::SmallString<16> Str;
  llvm::raw_svector_ostream(Str)
    << (isTargetIPhoneOS() ? "ios" : "macosx")
    << Version[0] << "." << Version[1] << "." << Version[2];
  Triple.setOSName(Str.str());

  return Triple.getTriple();
}

Tool &Darwin::SelectTool(const Compilation &C, const JobAction &JA,
                         const ActionList &Inputs) const {
  Action::ActionClass Key;

  if (getDriver().ShouldUseClangCompiler(C, JA, getTriple())) {
    // Fallback to llvm-gcc for i386 kext compiles, we don't support that ABI.
    if (Inputs.size() == 1 &&
        types::isCXX(Inputs[0]->getType()) &&
        getTriple().getOS() == llvm::Triple::Darwin &&
        getTriple().getArch() == llvm::Triple::x86 &&
        (C.getArgs().getLastArg(options::OPT_fapple_kext) ||
         C.getArgs().getLastArg(options::OPT_mkernel)))
      Key = JA.getKind();
    else
      Key = Action::AnalyzeJobClass;
  } else
    Key = JA.getKind();

  // FIXME: This doesn't belong here, but ideally we will support static soon
  // anyway.
  bool HasStatic = (C.getArgs().hasArg(options::OPT_mkernel) ||
                    C.getArgs().hasArg(options::OPT_static) ||
                    C.getArgs().hasArg(options::OPT_fapple_kext));
  bool IsIADefault = IsIntegratedAssemblerDefault() && !HasStatic;
  bool UseIntegratedAs = C.getArgs().hasFlag(options::OPT_integrated_as,
                                             options::OPT_no_integrated_as,
                                             IsIADefault);

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::InputClass:
    case Action::BindArchClass:
      llvm_unreachable("Invalid tool kind.");
    case Action::PreprocessJobClass:
      T = new tools::darwin::Preprocess(*this); break;
    case Action::AnalyzeJobClass:
      T = new tools::Clang(*this); break;
    case Action::PrecompileJobClass:
    case Action::CompileJobClass:
      T = new tools::darwin::Compile(*this); break;
    case Action::AssembleJobClass: {
      if (UseIntegratedAs)
        T = new tools::ClangAs(*this);
      else
        T = new tools::darwin::Assemble(*this);
      break;
    }
    case Action::LinkJobClass:
      T = new tools::darwin::Link(*this); break;
    case Action::LipoJobClass:
      T = new tools::darwin::Lipo(*this); break;
    case Action::DsymutilJobClass:
      T = new tools::darwin::Dsymutil(*this); break;
    case Action::VerifyJobClass:
      T = new tools::darwin::VerifyDebug(*this); break;
    }
  }

  return *T;
}


DarwinClang::DarwinClang(const HostInfo &Host, const llvm::Triple& Triple)
  : Darwin(Host, Triple)
{
  getProgramPaths().push_back(getDriver().getInstalledDir());
  if (getDriver().getInstalledDir() != getDriver().Dir)
    getProgramPaths().push_back(getDriver().Dir);

  // We expect 'as', 'ld', etc. to be adjacent to our install dir.
  getProgramPaths().push_back(getDriver().getInstalledDir());
  if (getDriver().getInstalledDir() != getDriver().Dir)
    getProgramPaths().push_back(getDriver().Dir);

  // For fallback, we need to know how to find the GCC cc1 executables, so we
  // also add the GCC libexec paths. This is legacy code that can be removed
  // once fallback is no longer useful.
  AddGCCLibexecPath(DarwinVersion[0]);
  AddGCCLibexecPath(DarwinVersion[0] - 2);
  AddGCCLibexecPath(DarwinVersion[0] - 1);
  AddGCCLibexecPath(DarwinVersion[0] + 1);
  AddGCCLibexecPath(DarwinVersion[0] + 2);
}

void DarwinClang::AddGCCLibexecPath(unsigned darwinVersion) {
  std::string ToolChainDir = "i686-apple-darwin";
  ToolChainDir += llvm::utostr(darwinVersion);
  ToolChainDir += "/4.2.1";

  std::string Path = getDriver().Dir;
  Path += "/../llvm-gcc-4.2/libexec/gcc/";
  Path += ToolChainDir;
  getProgramPaths().push_back(Path);

  Path = "/usr/llvm-gcc-4.2/libexec/gcc/";
  Path += ToolChainDir;
  getProgramPaths().push_back(Path);
}

void DarwinClang::AddLinkSearchPathArgs(const ArgList &Args,
                                       ArgStringList &CmdArgs) const {
  // The Clang toolchain uses explicit paths for internal libraries.

  // Unfortunately, we still might depend on a few of the libraries that are
  // only available in the gcc library directory (in particular
  // libstdc++.dylib). For now, hardcode the path to the known install location.
  llvm::sys::Path P(getDriver().Dir);
  P.eraseComponent(); // .../usr/bin -> ../usr
  P.appendComponent("lib");
  P.appendComponent("gcc");
  switch (getTriple().getArch()) {
  default:
    llvm_unreachable("Invalid Darwin arch!");
  case llvm::Triple::x86:
  case llvm::Triple::x86_64:
    P.appendComponent("i686-apple-darwin10");
    break;
  case llvm::Triple::arm:
  case llvm::Triple::thumb:
    P.appendComponent("arm-apple-darwin10");
    break;
  case llvm::Triple::ppc:
  case llvm::Triple::ppc64:
    P.appendComponent("powerpc-apple-darwin10");
    break;
  }
  P.appendComponent("4.2.1");

  // Determine the arch specific GCC subdirectory.
  const char *ArchSpecificDir = 0;
  switch (getTriple().getArch()) {
  default:
    break;
  case llvm::Triple::arm:
  case llvm::Triple::thumb: {
    std::string Triple = ComputeLLVMTriple(Args);
    StringRef TripleStr = Triple;
    if (TripleStr.startswith("armv5") || TripleStr.startswith("thumbv5"))
      ArchSpecificDir = "v5";
    else if (TripleStr.startswith("armv6") || TripleStr.startswith("thumbv6"))
      ArchSpecificDir = "v6";
    else if (TripleStr.startswith("armv7") || TripleStr.startswith("thumbv7"))
      ArchSpecificDir = "v7";
    break;
  }
  case llvm::Triple::ppc64:
    ArchSpecificDir = "ppc64";
    break;
  case llvm::Triple::x86_64:
    ArchSpecificDir = "x86_64";
    break;
  }

  if (ArchSpecificDir) {
    P.appendComponent(ArchSpecificDir);
    bool Exists;
    if (!llvm::sys::fs::exists(P.str(), Exists) && Exists)
      CmdArgs.push_back(Args.MakeArgString("-L" + P.str()));
    P.eraseComponent();
  }

  bool Exists;
  if (!llvm::sys::fs::exists(P.str(), Exists) && Exists)
    CmdArgs.push_back(Args.MakeArgString("-L" + P.str()));
}

void DarwinClang::AddLinkARCArgs(const ArgList &Args,
                                 ArgStringList &CmdArgs) const {

  CmdArgs.push_back("-force_load");
  llvm::sys::Path P(getDriver().ClangExecutable);
  P.eraseComponent(); // 'clang'
  P.eraseComponent(); // 'bin'
  P.appendComponent("lib");
  P.appendComponent("arc");
  P.appendComponent("libarclite_");
  std::string s = P.str();
  // Mash in the platform.
  if (isTargetIPhoneOS())
    s += "iphoneos";
  // FIXME: isTargetIphoneOSSimulator() is not returning true.
  else if (ARCRuntimeForSimulator != ARCSimulator_None)
    s += "iphonesimulator";
  else
    s += "macosx";
  s += ".a";

  CmdArgs.push_back(Args.MakeArgString(s));
}

void DarwinClang::AddLinkRuntimeLib(const ArgList &Args,
                                    ArgStringList &CmdArgs,
                                    const char *DarwinStaticLib) const {
  llvm::sys::Path P(getDriver().ResourceDir);
  P.appendComponent("lib");
  P.appendComponent("darwin");
  P.appendComponent(DarwinStaticLib);

  // For now, allow missing resource libraries to support developers who may
  // not have compiler-rt checked out or integrated into their build.
  bool Exists;
  if (!llvm::sys::fs::exists(P.str(), Exists) && Exists)
    CmdArgs.push_back(Args.MakeArgString(P.str()));
}

void DarwinClang::AddLinkRuntimeLibArgs(const ArgList &Args,
                                        ArgStringList &CmdArgs) const {
  // Darwin doesn't support real static executables, don't link any runtime
  // libraries with -static.
  if (Args.hasArg(options::OPT_static))
    return;

  // Reject -static-libgcc for now, we can deal with this when and if someone
  // cares. This is useful in situations where someone wants to statically link
  // something like libstdc++, and needs its runtime support routines.
  if (const Arg *A = Args.getLastArg(options::OPT_static_libgcc)) {
    getDriver().Diag(diag::err_drv_unsupported_opt)
      << A->getAsString(Args);
    return;
  }

  // Otherwise link libSystem, then the dynamic runtime library, and finally any
  // target specific static runtime library.
  CmdArgs.push_back("-lSystem");

  // Select the dynamic runtime library and the target specific static library.
  if (isTargetIPhoneOS()) {
    // If we are compiling as iOS / simulator, don't attempt to link libgcc_s.1,
    // it never went into the SDK.
    if (!isTargetIOSSimulator())
        CmdArgs.push_back("-lgcc_s.1");

    // We currently always need a static runtime library for iOS.
    AddLinkRuntimeLib(Args, CmdArgs, "libclang_rt.ios.a");
  } else {
    // The dynamic runtime library was merged with libSystem for 10.6 and
    // beyond; only 10.4 and 10.5 need an additional runtime library.
    if (isMacosxVersionLT(10, 5))
      CmdArgs.push_back("-lgcc_s.10.4");
    else if (isMacosxVersionLT(10, 6))
      CmdArgs.push_back("-lgcc_s.10.5");

    // For OS X, we thought we would only need a static runtime library when
    // targeting 10.4, to provide versions of the static functions which were
    // omitted from 10.4.dylib.
    //
    // Unfortunately, that turned out to not be true, because Darwin system
    // headers can still use eprintf on i386, and it is not exported from
    // libSystem. Therefore, we still must provide a runtime library just for
    // the tiny tiny handful of projects that *might* use that symbol.
    if (isMacosxVersionLT(10, 5)) {
      AddLinkRuntimeLib(Args, CmdArgs, "libclang_rt.10.4.a");
    } else {
      if (getTriple().getArch() == llvm::Triple::x86)
        AddLinkRuntimeLib(Args, CmdArgs, "libclang_rt.eprintf.a");
      AddLinkRuntimeLib(Args, CmdArgs, "libclang_rt.osx.a");
    }
  }
}

static inline StringRef SimulatorVersionDefineName() {
  return "__IPHONE_OS_VERSION_MIN_REQUIRED";
}

/// \brief Parse the simulator version define:
/// __IPHONE_OS_VERSION_MIN_REQUIRED=([0-9])([0-9][0-9])([0-9][0-9])
// and return the grouped values as integers, e.g:
//   __IPHONE_OS_VERSION_MIN_REQUIRED=40201
// will return Major=4, Minor=2, Micro=1.
static bool GetVersionFromSimulatorDefine(StringRef define,
                                          unsigned &Major, unsigned &Minor,
                                          unsigned &Micro) {
  assert(define.startswith(SimulatorVersionDefineName()));
  StringRef name, version;
  llvm::tie(name, version) = define.split('=');
  if (version.empty())
    return false;
  std::string verstr = version.str();
  char *end;
  unsigned num = (unsigned) strtol(verstr.c_str(), &end, 10);
  if (*end != '\0')
    return false;
  Major = num / 10000;
  num = num % 10000;
  Minor = num / 100;
  Micro = num % 100;
  return true;
}

void Darwin::AddDeploymentTarget(DerivedArgList &Args) const {
  const OptTable &Opts = getDriver().getOpts();

  Arg *OSXVersion = Args.getLastArg(options::OPT_mmacosx_version_min_EQ);
  Arg *iOSVersion = Args.getLastArg(options::OPT_miphoneos_version_min_EQ);
  Arg *iOSSimVersion = Args.getLastArg(
    options::OPT_mios_simulator_version_min_EQ);

  // FIXME: HACK! When compiling for the simulator we don't get a
  // '-miphoneos-version-min' to help us know whether there is an ARC runtime
  // or not; try to parse a __IPHONE_OS_VERSION_MIN_REQUIRED
  // define passed in command-line.
  if (!iOSVersion) {
    for (arg_iterator it = Args.filtered_begin(options::OPT_D),
           ie = Args.filtered_end(); it != ie; ++it) {
      StringRef define = (*it)->getValue(Args);
      if (define.startswith(SimulatorVersionDefineName())) {
        unsigned Major = 0, Minor = 0, Micro = 0;
        if (GetVersionFromSimulatorDefine(define, Major, Minor, Micro) &&
            Major < 10 && Minor < 100 && Micro < 100) {
          ARCRuntimeForSimulator = Major < 5 ? ARCSimulator_NoARCRuntime
                                             : ARCSimulator_HasARCRuntime;
        }
        break;
      }
    }
  }

  if (OSXVersion && (iOSVersion || iOSSimVersion)) {
    getDriver().Diag(diag::err_drv_argument_not_allowed_with)
          << OSXVersion->getAsString(Args)
          << (iOSVersion ? iOSVersion : iOSSimVersion)->getAsString(Args);
    iOSVersion = iOSSimVersion = 0;
  } else if (iOSVersion && iOSSimVersion) {
    getDriver().Diag(diag::err_drv_argument_not_allowed_with)
          << iOSVersion->getAsString(Args)
          << iOSSimVersion->getAsString(Args);
    iOSSimVersion = 0;
  } else if (!OSXVersion && !iOSVersion && !iOSSimVersion) {
    // If no deployment target was specified on the command line, check for
    // environment defines.
    StringRef OSXTarget;
    StringRef iOSTarget;
    StringRef iOSSimTarget;
    if (char *env = ::getenv("MACOSX_DEPLOYMENT_TARGET"))
      OSXTarget = env;
    if (char *env = ::getenv("IPHONEOS_DEPLOYMENT_TARGET"))
      iOSTarget = env;
    if (char *env = ::getenv("IOS_SIMULATOR_DEPLOYMENT_TARGET"))
      iOSSimTarget = env;

    // If no '-miphoneos-version-min' specified on the command line and 
    // IPHONEOS_DEPLOYMENT_TARGET is not defined, see if we can set the default
    // based on isysroot.
    if (iOSTarget.empty()) {
      if (const Arg *A = Args.getLastArg(options::OPT_isysroot)) {
        StringRef first, second;
        StringRef isysroot = A->getValue(Args);
        llvm::tie(first, second) = isysroot.split(StringRef("SDKs/iPhoneOS"));
        if (second != "")
          iOSTarget = second.substr(0,3);
      }
    }

    // If no OSX or iOS target has been specified and we're compiling for armv7,
    // go ahead as assume we're targeting iOS.
    if (OSXTarget.empty() && iOSTarget.empty())
      if (getDarwinArchName(Args) == "armv7")
        iOSTarget = "0.0";

    // Handle conflicting deployment targets
    //
    // FIXME: Don't hardcode default here.

    // Do not allow conflicts with the iOS simulator target.
    if (!iOSSimTarget.empty() && (!OSXTarget.empty() || !iOSTarget.empty())) {
      getDriver().Diag(diag::err_drv_conflicting_deployment_targets)
        << "IOS_SIMULATOR_DEPLOYMENT_TARGET"
        << (!OSXTarget.empty() ? "MACOSX_DEPLOYMENT_TARGET" :
            "IPHONEOS_DEPLOYMENT_TARGET");
    }

    // Allow conflicts among OSX and iOS for historical reasons, but choose the
    // default platform.
    if (!OSXTarget.empty() && !iOSTarget.empty()) {
      if (getTriple().getArch() == llvm::Triple::arm ||
          getTriple().getArch() == llvm::Triple::thumb)
        OSXTarget = "";
      else
        iOSTarget = "";
    }

    if (!OSXTarget.empty()) {
      const Option *O = Opts.getOption(options::OPT_mmacosx_version_min_EQ);
      OSXVersion = Args.MakeJoinedArg(0, O, OSXTarget);
      Args.append(OSXVersion);
    } else if (!iOSTarget.empty()) {
      const Option *O = Opts.getOption(options::OPT_miphoneos_version_min_EQ);
      iOSVersion = Args.MakeJoinedArg(0, O, iOSTarget);
      Args.append(iOSVersion);
    } else if (!iOSSimTarget.empty()) {
      const Option *O = Opts.getOption(
        options::OPT_mios_simulator_version_min_EQ);
      iOSSimVersion = Args.MakeJoinedArg(0, O, iOSSimTarget);
      Args.append(iOSSimVersion);
    } else {
      // Otherwise, assume we are targeting OS X.
      const Option *O = Opts.getOption(options::OPT_mmacosx_version_min_EQ);
      OSXVersion = Args.MakeJoinedArg(0, O, MacosxVersionMin);
      Args.append(OSXVersion);
    }
  }

  // Reject invalid architecture combinations.
  if (iOSSimVersion && (getTriple().getArch() != llvm::Triple::x86 &&
                        getTriple().getArch() != llvm::Triple::x86_64)) {
    getDriver().Diag(diag::err_drv_invalid_arch_for_deployment_target)
      << getTriple().getArchName() << iOSSimVersion->getAsString(Args);
  }

  // Set the tool chain target information.
  unsigned Major, Minor, Micro;
  bool HadExtra;
  if (OSXVersion) {
    assert((!iOSVersion && !iOSSimVersion) && "Unknown target platform!");
    if (!Driver::GetReleaseVersion(OSXVersion->getValue(Args), Major, Minor,
                                   Micro, HadExtra) || HadExtra ||
        Major != 10 || Minor >= 100 || Micro >= 100)
      getDriver().Diag(diag::err_drv_invalid_version_number)
        << OSXVersion->getAsString(Args);
  } else {
    const Arg *Version = iOSVersion ? iOSVersion : iOSSimVersion;
    assert(Version && "Unknown target platform!");
    if (!Driver::GetReleaseVersion(Version->getValue(Args), Major, Minor,
                                   Micro, HadExtra) || HadExtra ||
        Major >= 10 || Minor >= 100 || Micro >= 100)
      getDriver().Diag(diag::err_drv_invalid_version_number)
        << Version->getAsString(Args);
  }

  bool IsIOSSim = bool(iOSSimVersion);

  // In GCC, the simulator historically was treated as being OS X in some
  // contexts, like determining the link logic, despite generally being called
  // with an iOS deployment target. For compatibility, we detect the
  // simulator as iOS + x86, and treat it differently in a few contexts.
  if (iOSVersion && (getTriple().getArch() == llvm::Triple::x86 ||
                     getTriple().getArch() == llvm::Triple::x86_64))
    IsIOSSim = true;

  setTarget(/*IsIPhoneOS=*/ !OSXVersion, Major, Minor, Micro, IsIOSSim);
}

void DarwinClang::AddCXXStdlibLibArgs(const ArgList &Args,
                                      ArgStringList &CmdArgs) const {
  CXXStdlibType Type = GetCXXStdlibType(Args);

  switch (Type) {
  case ToolChain::CST_Libcxx:
    CmdArgs.push_back("-lc++");
    break;

  case ToolChain::CST_Libstdcxx: {
    // Unfortunately, -lstdc++ doesn't always exist in the standard search path;
    // it was previously found in the gcc lib dir. However, for all the Darwin
    // platforms we care about it was -lstdc++.6, so we search for that
    // explicitly if we can't see an obvious -lstdc++ candidate.

    // Check in the sysroot first.
    bool Exists;
    if (const Arg *A = Args.getLastArg(options::OPT_isysroot)) {
      llvm::sys::Path P(A->getValue(Args));
      P.appendComponent("usr");
      P.appendComponent("lib");
      P.appendComponent("libstdc++.dylib");

      if (llvm::sys::fs::exists(P.str(), Exists) || !Exists) {
        P.eraseComponent();
        P.appendComponent("libstdc++.6.dylib");
        if (!llvm::sys::fs::exists(P.str(), Exists) && Exists) {
          CmdArgs.push_back(Args.MakeArgString(P.str()));
          return;
        }
      }
    }

    // Otherwise, look in the root.
    if ((llvm::sys::fs::exists("/usr/lib/libstdc++.dylib", Exists) || !Exists)&&
      (!llvm::sys::fs::exists("/usr/lib/libstdc++.6.dylib", Exists) && Exists)){
      CmdArgs.push_back("/usr/lib/libstdc++.6.dylib");
      return;
    }

    // Otherwise, let the linker search.
    CmdArgs.push_back("-lstdc++");
    break;
  }
  }
}

void DarwinClang::AddCCKextLibArgs(const ArgList &Args,
                                   ArgStringList &CmdArgs) const {

  // For Darwin platforms, use the compiler-rt-based support library
  // instead of the gcc-provided one (which is also incidentally
  // only present in the gcc lib dir, which makes it hard to find).

  llvm::sys::Path P(getDriver().ResourceDir);
  P.appendComponent("lib");
  P.appendComponent("darwin");
  P.appendComponent("libclang_rt.cc_kext.a");

  // For now, allow missing resource libraries to support developers who may
  // not have compiler-rt checked out or integrated into their build.
  bool Exists;
  if (!llvm::sys::fs::exists(P.str(), Exists) && Exists)
    CmdArgs.push_back(Args.MakeArgString(P.str()));
}

DerivedArgList *Darwin::TranslateArgs(const DerivedArgList &Args,
                                      const char *BoundArch) const {
  DerivedArgList *DAL = new DerivedArgList(Args.getBaseArgs());
  const OptTable &Opts = getDriver().getOpts();

  // FIXME: We really want to get out of the tool chain level argument
  // translation business, as it makes the driver functionality much
  // more opaque. For now, we follow gcc closely solely for the
  // purpose of easily achieving feature parity & testability. Once we
  // have something that works, we should reevaluate each translation
  // and try to push it down into tool specific logic.

  for (ArgList::const_iterator it = Args.begin(),
         ie = Args.end(); it != ie; ++it) {
    Arg *A = *it;

    if (A->getOption().matches(options::OPT_Xarch__)) {
      // Skip this argument unless the architecture matches either the toolchain
      // triple arch, or the arch being bound.
      //
      // FIXME: Canonicalize name.
      StringRef XarchArch = A->getValue(Args, 0);
      if (!(XarchArch == getArchName()  ||
            (BoundArch && XarchArch == BoundArch)))
        continue;

      Arg *OriginalArg = A;
      unsigned Index = Args.getBaseArgs().MakeIndex(A->getValue(Args, 1));
      unsigned Prev = Index;
      Arg *XarchArg = Opts.ParseOneArg(Args, Index);

      // If the argument parsing failed or more than one argument was
      // consumed, the -Xarch_ argument's parameter tried to consume
      // extra arguments. Emit an error and ignore.
      //
      // We also want to disallow any options which would alter the
      // driver behavior; that isn't going to work in our model. We
      // use isDriverOption() as an approximation, although things
      // like -O4 are going to slip through.
      if (!XarchArg || Index > Prev + 1) {
        getDriver().Diag(diag::err_drv_invalid_Xarch_argument_with_args)
          << A->getAsString(Args);
        continue;
      } else if (XarchArg->getOption().isDriverOption()) {
        getDriver().Diag(diag::err_drv_invalid_Xarch_argument_isdriver)
          << A->getAsString(Args);
        continue;
      }

      XarchArg->setBaseArg(A);
      A = XarchArg;

      DAL->AddSynthesizedArg(A);

      // Linker input arguments require custom handling. The problem is that we
      // have already constructed the phase actions, so we can not treat them as
      // "input arguments".
      if (A->getOption().isLinkerInput()) {
        // Convert the argument into individual Zlinker_input_args.
        for (unsigned i = 0, e = A->getNumValues(); i != e; ++i) {
          DAL->AddSeparateArg(OriginalArg,
                              Opts.getOption(options::OPT_Zlinker_input),
                              A->getValue(Args, i));

        }
        continue;
      }
    }

    // Sob. These is strictly gcc compatible for the time being. Apple
    // gcc translates options twice, which means that self-expanding
    // options add duplicates.
    switch ((options::ID) A->getOption().getID()) {
    default:
      DAL->append(A);
      break;

    case options::OPT_mkernel:
    case options::OPT_fapple_kext:
      DAL->append(A);
      DAL->AddFlagArg(A, Opts.getOption(options::OPT_static));
      break;

    case options::OPT_dependency_file:
      DAL->AddSeparateArg(A, Opts.getOption(options::OPT_MF),
                          A->getValue(Args));
      break;

    case options::OPT_gfull:
      DAL->AddFlagArg(A, Opts.getOption(options::OPT_g_Flag));
      DAL->AddFlagArg(A,
               Opts.getOption(options::OPT_fno_eliminate_unused_debug_symbols));
      break;

    case options::OPT_gused:
      DAL->AddFlagArg(A, Opts.getOption(options::OPT_g_Flag));
      DAL->AddFlagArg(A,
             Opts.getOption(options::OPT_feliminate_unused_debug_symbols));
      break;

    case options::OPT_shared:
      DAL->AddFlagArg(A, Opts.getOption(options::OPT_dynamiclib));
      break;

    case options::OPT_fconstant_cfstrings:
      DAL->AddFlagArg(A, Opts.getOption(options::OPT_mconstant_cfstrings));
      break;

    case options::OPT_fno_constant_cfstrings:
      DAL->AddFlagArg(A, Opts.getOption(options::OPT_mno_constant_cfstrings));
      break;

    case options::OPT_Wnonportable_cfstrings:
      DAL->AddFlagArg(A,
                      Opts.getOption(options::OPT_mwarn_nonportable_cfstrings));
      break;

    case options::OPT_Wno_nonportable_cfstrings:
      DAL->AddFlagArg(A,
                   Opts.getOption(options::OPT_mno_warn_nonportable_cfstrings));
      break;

    case options::OPT_fpascal_strings:
      DAL->AddFlagArg(A, Opts.getOption(options::OPT_mpascal_strings));
      break;

    case options::OPT_fno_pascal_strings:
      DAL->AddFlagArg(A, Opts.getOption(options::OPT_mno_pascal_strings));
      break;
    }
  }

  if (getTriple().getArch() == llvm::Triple::x86 ||
      getTriple().getArch() == llvm::Triple::x86_64)
    if (!Args.hasArgNoClaim(options::OPT_mtune_EQ))
      DAL->AddJoinedArg(0, Opts.getOption(options::OPT_mtune_EQ), "core2");

  // Add the arch options based on the particular spelling of -arch, to match
  // how the driver driver works.
  if (BoundArch) {
    StringRef Name = BoundArch;
    const Option *MCpu = Opts.getOption(options::OPT_mcpu_EQ);
    const Option *MArch = Opts.getOption(options::OPT_march_EQ);

    // This code must be kept in sync with LLVM's getArchTypeForDarwinArch,
    // which defines the list of which architectures we accept.
    if (Name == "ppc")
      ;
    else if (Name == "ppc601")
      DAL->AddJoinedArg(0, MCpu, "601");
    else if (Name == "ppc603")
      DAL->AddJoinedArg(0, MCpu, "603");
    else if (Name == "ppc604")
      DAL->AddJoinedArg(0, MCpu, "604");
    else if (Name == "ppc604e")
      DAL->AddJoinedArg(0, MCpu, "604e");
    else if (Name == "ppc750")
      DAL->AddJoinedArg(0, MCpu, "750");
    else if (Name == "ppc7400")
      DAL->AddJoinedArg(0, MCpu, "7400");
    else if (Name == "ppc7450")
      DAL->AddJoinedArg(0, MCpu, "7450");
    else if (Name == "ppc970")
      DAL->AddJoinedArg(0, MCpu, "970");

    else if (Name == "ppc64")
      DAL->AddFlagArg(0, Opts.getOption(options::OPT_m64));

    else if (Name == "i386")
      ;
    else if (Name == "i486")
      DAL->AddJoinedArg(0, MArch, "i486");
    else if (Name == "i586")
      DAL->AddJoinedArg(0, MArch, "i586");
    else if (Name == "i686")
      DAL->AddJoinedArg(0, MArch, "i686");
    else if (Name == "pentium")
      DAL->AddJoinedArg(0, MArch, "pentium");
    else if (Name == "pentium2")
      DAL->AddJoinedArg(0, MArch, "pentium2");
    else if (Name == "pentpro")
      DAL->AddJoinedArg(0, MArch, "pentiumpro");
    else if (Name == "pentIIm3")
      DAL->AddJoinedArg(0, MArch, "pentium2");

    else if (Name == "x86_64")
      DAL->AddFlagArg(0, Opts.getOption(options::OPT_m64));

    else if (Name == "arm")
      DAL->AddJoinedArg(0, MArch, "armv4t");
    else if (Name == "armv4t")
      DAL->AddJoinedArg(0, MArch, "armv4t");
    else if (Name == "armv5")
      DAL->AddJoinedArg(0, MArch, "armv5tej");
    else if (Name == "xscale")
      DAL->AddJoinedArg(0, MArch, "xscale");
    else if (Name == "armv6")
      DAL->AddJoinedArg(0, MArch, "armv6k");
    else if (Name == "armv7")
      DAL->AddJoinedArg(0, MArch, "armv7a");

    else
      llvm_unreachable("invalid Darwin arch");
  }

  // Add an explicit version min argument for the deployment target. We do this
  // after argument translation because -Xarch_ arguments may add a version min
  // argument.
  AddDeploymentTarget(*DAL);

  return DAL;
}

bool Darwin::IsUnwindTablesDefault() const {
  // FIXME: Gross; we should probably have some separate target
  // definition, possibly even reusing the one in clang.
  return getArchName() == "x86_64";
}

bool Darwin::UseDwarfDebugFlags() const {
  if (const char *S = ::getenv("RC_DEBUG_OPTIONS"))
    return S[0] != '\0';
  return false;
}

bool Darwin::UseSjLjExceptions() const {
  // Darwin uses SjLj exceptions on ARM.
  return (getTriple().getArch() == llvm::Triple::arm ||
          getTriple().getArch() == llvm::Triple::thumb);
}

const char *Darwin::GetDefaultRelocationModel() const {
  return "pic";
}

const char *Darwin::GetForcedPicModel() const {
  if (getArchName() == "x86_64")
    return "pic";
  return 0;
}

bool Darwin::SupportsProfiling() const {
  // Profiling instrumentation is only supported on x86.
  return getArchName() == "i386" || getArchName() == "x86_64";
}

bool Darwin::SupportsObjCGC() const {
  // Garbage collection is supported everywhere except on iPhone OS.
  return !isTargetIPhoneOS();
}

std::string
Darwin_Generic_GCC::ComputeEffectiveClangTriple(const ArgList &Args,
                                                types::ID InputType) const {
  return ComputeLLVMTriple(Args, InputType);
}

/// Generic_GCC - A tool chain using the 'gcc' command to perform
/// all subcommands; this relies on gcc translating the majority of
/// command line options.

Generic_GCC::Generic_GCC(const HostInfo &Host, const llvm::Triple& Triple)
  : ToolChain(Host, Triple) {
  getProgramPaths().push_back(getDriver().getInstalledDir());
  if (getDriver().getInstalledDir() != getDriver().Dir)
    getProgramPaths().push_back(getDriver().Dir);
}

Generic_GCC::~Generic_GCC() {
  // Free tool implementations.
  for (llvm::DenseMap<unsigned, Tool*>::iterator
         it = Tools.begin(), ie = Tools.end(); it != ie; ++it)
    delete it->second;
}

Tool &Generic_GCC::SelectTool(const Compilation &C,
                              const JobAction &JA,
                              const ActionList &Inputs) const {
  Action::ActionClass Key;
  if (getDriver().ShouldUseClangCompiler(C, JA, getTriple()))
    Key = Action::AnalyzeJobClass;
  else
    Key = JA.getKind();

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::InputClass:
    case Action::BindArchClass:
      llvm_unreachable("Invalid tool kind.");
    case Action::PreprocessJobClass:
      T = new tools::gcc::Preprocess(*this); break;
    case Action::PrecompileJobClass:
      T = new tools::gcc::Precompile(*this); break;
    case Action::AnalyzeJobClass:
      T = new tools::Clang(*this); break;
    case Action::CompileJobClass:
      T = new tools::gcc::Compile(*this); break;
    case Action::AssembleJobClass:
      T = new tools::gcc::Assemble(*this); break;
    case Action::LinkJobClass:
      T = new tools::gcc::Link(*this); break;

      // This is a bit ungeneric, but the only platform using a driver
      // driver is Darwin.
    case Action::LipoJobClass:
      T = new tools::darwin::Lipo(*this); break;
    case Action::DsymutilJobClass:
      T = new tools::darwin::Dsymutil(*this); break;
    case Action::VerifyJobClass:
      T = new tools::darwin::VerifyDebug(*this); break;
    }
  }

  return *T;
}

bool Generic_GCC::IsUnwindTablesDefault() const {
  // FIXME: Gross; we should probably have some separate target
  // definition, possibly even reusing the one in clang.
  return getArchName() == "x86_64";
}

const char *Generic_GCC::GetDefaultRelocationModel() const {
  return "static";
}

const char *Generic_GCC::GetForcedPicModel() const {
  return 0;
}

/// TCEToolChain - A tool chain using the llvm bitcode tools to perform
/// all subcommands. See http://tce.cs.tut.fi for our peculiar target.
/// Currently does not support anything else but compilation.

TCEToolChain::TCEToolChain(const HostInfo &Host, const llvm::Triple& Triple)
  : ToolChain(Host, Triple) {
  // Path mangling to find libexec
  std::string Path(getDriver().Dir);

  Path += "/../libexec";
  getProgramPaths().push_back(Path);
}

TCEToolChain::~TCEToolChain() {
  for (llvm::DenseMap<unsigned, Tool*>::iterator
           it = Tools.begin(), ie = Tools.end(); it != ie; ++it)
      delete it->second;
}

bool TCEToolChain::IsMathErrnoDefault() const {
  return true;
}

bool TCEToolChain::IsUnwindTablesDefault() const {
  return false;
}

const char *TCEToolChain::GetDefaultRelocationModel() const {
  return "static";
}

const char *TCEToolChain::GetForcedPicModel() const {
  return 0;
}

Tool &TCEToolChain::SelectTool(const Compilation &C,
                            const JobAction &JA,
                               const ActionList &Inputs) const {
  Action::ActionClass Key;
  Key = Action::AnalyzeJobClass;

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::PreprocessJobClass:
      T = new tools::gcc::Preprocess(*this); break;
    case Action::AnalyzeJobClass:
      T = new tools::Clang(*this); break;
    default:
     llvm_unreachable("Unsupported action for TCE target.");
    }
  }
  return *T;
}

/// OpenBSD - OpenBSD tool chain which can call as(1) and ld(1) directly.

OpenBSD::OpenBSD(const HostInfo &Host, const llvm::Triple& Triple)
  : Generic_ELF(Host, Triple) {
  getFilePaths().push_back(getDriver().Dir + "/../lib");
  getFilePaths().push_back("/usr/lib");
}

Tool &OpenBSD::SelectTool(const Compilation &C, const JobAction &JA,
                          const ActionList &Inputs) const {
  Action::ActionClass Key;
  if (getDriver().ShouldUseClangCompiler(C, JA, getTriple()))
    Key = Action::AnalyzeJobClass;
  else
    Key = JA.getKind();

  bool UseIntegratedAs = C.getArgs().hasFlag(options::OPT_integrated_as,
                                             options::OPT_no_integrated_as,
                                             IsIntegratedAssemblerDefault());

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::AssembleJobClass: {
      if (UseIntegratedAs)
        T = new tools::ClangAs(*this);
      else
        T = new tools::openbsd::Assemble(*this);
      break;
    }
    case Action::LinkJobClass:
      T = new tools::openbsd::Link(*this); break;
    default:
      T = &Generic_GCC::SelectTool(C, JA, Inputs);
    }
  }

  return *T;
}

/// FreeBSD - FreeBSD tool chain which can call as(1) and ld(1) directly.

FreeBSD::FreeBSD(const HostInfo &Host, const llvm::Triple& Triple)
  : Generic_ELF(Host, Triple) {

  // Determine if we are compiling 32-bit code on an x86_64 platform.
  bool Lib32 = false;
  if (Triple.getArch() == llvm::Triple::x86 &&
      llvm::Triple(getDriver().DefaultHostTriple).getArch() ==
        llvm::Triple::x86_64)
    Lib32 = true;

  if (Triple.getArch() == llvm::Triple::ppc &&
      llvm::Triple(getDriver().DefaultHostTriple).getArch() ==
        llvm::Triple::ppc64)
    Lib32 = true;

  if (Lib32) {
    getFilePaths().push_back("/usr/lib32");
  } else {
    getFilePaths().push_back("/usr/lib");
  }
}

Tool &FreeBSD::SelectTool(const Compilation &C, const JobAction &JA,
                          const ActionList &Inputs) const {
  Action::ActionClass Key;
  if (getDriver().ShouldUseClangCompiler(C, JA, getTriple()))
    Key = Action::AnalyzeJobClass;
  else
    Key = JA.getKind();

  bool UseIntegratedAs = C.getArgs().hasFlag(options::OPT_integrated_as,
                                             options::OPT_no_integrated_as,
                                             IsIntegratedAssemblerDefault());

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::AssembleJobClass:
      if (UseIntegratedAs)
        T = new tools::ClangAs(*this);
      else
        T = new tools::freebsd::Assemble(*this);
      break;
    case Action::LinkJobClass:
      T = new tools::freebsd::Link(*this); break;
    default:
      T = &Generic_GCC::SelectTool(C, JA, Inputs);
    }
  }

  return *T;
}

/// NetBSD - NetBSD tool chain which can call as(1) and ld(1) directly.

NetBSD::NetBSD(const HostInfo &Host, const llvm::Triple& Triple,
               const llvm::Triple& ToolTriple)
  : Generic_ELF(Host, Triple), ToolTriple(ToolTriple) {

  // Determine if we are compiling 32-bit code on an x86_64 platform.
  bool Lib32 = false;
  if (ToolTriple.getArch() == llvm::Triple::x86_64 &&
      Triple.getArch() == llvm::Triple::x86)
    Lib32 = true;

  if (getDriver().UseStdLib) {
    if (Lib32)
      getFilePaths().push_back("=/usr/lib/i386");
    else
      getFilePaths().push_back("=/usr/lib");
  }
}

Tool &NetBSD::SelectTool(const Compilation &C, const JobAction &JA,
                         const ActionList &Inputs) const {
  Action::ActionClass Key;
  if (getDriver().ShouldUseClangCompiler(C, JA, getTriple()))
    Key = Action::AnalyzeJobClass;
  else
    Key = JA.getKind();

  bool UseIntegratedAs = C.getArgs().hasFlag(options::OPT_integrated_as,
                                             options::OPT_no_integrated_as,
                                             IsIntegratedAssemblerDefault());

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::AssembleJobClass:
      if (UseIntegratedAs)
        T = new tools::ClangAs(*this);
      else
        T = new tools::netbsd::Assemble(*this, ToolTriple);
      break;
    case Action::LinkJobClass:
      T = new tools::netbsd::Link(*this, ToolTriple);
      break;
    default:
      T = &Generic_GCC::SelectTool(C, JA, Inputs);
    }
  }

  return *T;
}

/// Minix - Minix tool chain which can call as(1) and ld(1) directly.

Minix::Minix(const HostInfo &Host, const llvm::Triple& Triple)
  : Generic_GCC(Host, Triple) {
  getFilePaths().push_back(getDriver().Dir + "/../lib");
  getFilePaths().push_back("/usr/lib");
  getFilePaths().push_back("/usr/gnu/lib");
  getFilePaths().push_back("/usr/gnu/lib/gcc/i686-pc-minix/4.4.3");
}

Tool &Minix::SelectTool(const Compilation &C, const JobAction &JA,
                        const ActionList &Inputs) const {
  Action::ActionClass Key;
  if (getDriver().ShouldUseClangCompiler(C, JA, getTriple()))
    Key = Action::AnalyzeJobClass;
  else
    Key = JA.getKind();

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::AssembleJobClass:
      T = new tools::minix::Assemble(*this); break;
    case Action::LinkJobClass:
      T = new tools::minix::Link(*this); break;
    default:
      T = &Generic_GCC::SelectTool(C, JA, Inputs);
    }
  }

  return *T;
}

/// AuroraUX - AuroraUX tool chain which can call as(1) and ld(1) directly.

AuroraUX::AuroraUX(const HostInfo &Host, const llvm::Triple& Triple)
  : Generic_GCC(Host, Triple) {

  getProgramPaths().push_back(getDriver().getInstalledDir());
  if (getDriver().getInstalledDir() != getDriver().Dir)
    getProgramPaths().push_back(getDriver().Dir);

  getFilePaths().push_back(getDriver().Dir + "/../lib");
  getFilePaths().push_back("/usr/lib");
  getFilePaths().push_back("/usr/sfw/lib");
  getFilePaths().push_back("/opt/gcc4/lib");
  getFilePaths().push_back("/opt/gcc4/lib/gcc/i386-pc-solaris2.11/4.2.4");

}

Tool &AuroraUX::SelectTool(const Compilation &C, const JobAction &JA,
                           const ActionList &Inputs) const {
  Action::ActionClass Key;
  if (getDriver().ShouldUseClangCompiler(C, JA, getTriple()))
    Key = Action::AnalyzeJobClass;
  else
    Key = JA.getKind();

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::AssembleJobClass:
      T = new tools::auroraux::Assemble(*this); break;
    case Action::LinkJobClass:
      T = new tools::auroraux::Link(*this); break;
    default:
      T = &Generic_GCC::SelectTool(C, JA, Inputs);
    }
  }

  return *T;
}


/// Linux toolchain (very bare-bones at the moment).

enum LinuxDistro {
  ArchLinux,
  DebianLenny,
  DebianSqueeze,
  DebianWheezy,
  Exherbo,
  RHEL4,
  RHEL5,
  RHEL6,
  Fedora13,
  Fedora14,
  Fedora15,
  FedoraRawhide,
  OpenSuse11_3,
  OpenSuse11_4,
  OpenSuse12_1,
  UbuntuHardy,
  UbuntuIntrepid,
  UbuntuJaunty,
  UbuntuKarmic,
  UbuntuLucid,
  UbuntuMaverick,
  UbuntuNatty,
  UbuntuOneiric,
  UnknownDistro
};

static bool IsRedhat(enum LinuxDistro Distro) {
  return Distro == Fedora13 || Distro == Fedora14 ||
         Distro == Fedora15 || Distro == FedoraRawhide ||
         Distro == RHEL4 || Distro == RHEL5 || Distro == RHEL6;
}

static bool IsOpenSuse(enum LinuxDistro Distro) {
  return Distro == OpenSuse11_3 || Distro == OpenSuse11_4 ||
         Distro == OpenSuse12_1;
}

static bool IsDebian(enum LinuxDistro Distro) {
  return Distro == DebianLenny || Distro == DebianSqueeze ||
         Distro == DebianWheezy;
}

static bool IsUbuntu(enum LinuxDistro Distro) {
  return Distro == UbuntuHardy  || Distro == UbuntuIntrepid ||
         Distro == UbuntuLucid  || Distro == UbuntuMaverick ||
         Distro == UbuntuJaunty || Distro == UbuntuKarmic ||
         Distro == UbuntuNatty  || Distro == UbuntuOneiric;
}

// FIXME: This should be deleted. We should assume a multilib environment, and
// fallback gracefully if any parts of it are absent.
static bool HasMultilib(llvm::Triple::ArchType Arch, enum LinuxDistro Distro) {
  if (Arch == llvm::Triple::x86_64) {
    bool Exists;
    if (Distro == Exherbo &&
        (llvm::sys::fs::exists("/usr/lib32/libc.so", Exists) || !Exists))
      return false;
  }

  return true;
}

static LinuxDistro DetectLinuxDistro(llvm::Triple::ArchType Arch) {
  llvm::OwningPtr<llvm::MemoryBuffer> File;
  if (!llvm::MemoryBuffer::getFile("/etc/lsb-release", File)) {
    StringRef Data = File.get()->getBuffer();
    SmallVector<StringRef, 8> Lines;
    Data.split(Lines, "\n");
    for (unsigned int i = 0, s = Lines.size(); i < s; ++ i) {
      if (Lines[i] == "DISTRIB_CODENAME=hardy")
        return UbuntuHardy;
      else if (Lines[i] == "DISTRIB_CODENAME=intrepid")
        return UbuntuIntrepid;
      else if (Lines[i] == "DISTRIB_CODENAME=jaunty")
        return UbuntuJaunty;
      else if (Lines[i] == "DISTRIB_CODENAME=karmic")
        return UbuntuKarmic;
      else if (Lines[i] == "DISTRIB_CODENAME=lucid")
        return UbuntuLucid;
      else if (Lines[i] == "DISTRIB_CODENAME=maverick")
        return UbuntuMaverick;
      else if (Lines[i] == "DISTRIB_CODENAME=natty")
        return UbuntuNatty;
      else if (Lines[i] == "DISTRIB_CODENAME=oneiric")
        return UbuntuOneiric;
    }
    return UnknownDistro;
  }

  if (!llvm::MemoryBuffer::getFile("/etc/redhat-release", File)) {
    StringRef Data = File.get()->getBuffer();
    if (Data.startswith("Fedora release 15"))
      return Fedora15;
    else if (Data.startswith("Fedora release 14"))
      return Fedora14;
    else if (Data.startswith("Fedora release 13"))
      return Fedora13;
    else if (Data.startswith("Fedora release") &&
             Data.find("Rawhide") != StringRef::npos)
      return FedoraRawhide;
    else if (Data.startswith("Red Hat Enterprise Linux") &&
             Data.find("release 6") != StringRef::npos)
      return RHEL6;
    else if ((Data.startswith("Red Hat Enterprise Linux") ||
	      Data.startswith("CentOS")) &&
             Data.find("release 5") != StringRef::npos)
      return RHEL5;
    else if ((Data.startswith("Red Hat Enterprise Linux") ||
	      Data.startswith("CentOS")) &&
             Data.find("release 4") != StringRef::npos)
      return RHEL4;
    return UnknownDistro;
  }

  if (!llvm::MemoryBuffer::getFile("/etc/debian_version", File)) {
    StringRef Data = File.get()->getBuffer();
    if (Data[0] == '5')
      return DebianLenny;
    else if (Data.startswith("squeeze/sid"))
      return DebianSqueeze;
    else if (Data.startswith("wheezy/sid"))
      return DebianWheezy;
    return UnknownDistro;
  }

  if (!llvm::MemoryBuffer::getFile("/etc/SuSE-release", File)) {
    StringRef Data = File.get()->getBuffer();
    if (Data.startswith("openSUSE 11.3"))
      return OpenSuse11_3;
    else if (Data.startswith("openSUSE 11.4"))
      return OpenSuse11_4;
    else if (Data.startswith("openSUSE 12.1"))
      return OpenSuse12_1;
    return UnknownDistro;
  }

  bool Exists;
  if (!llvm::sys::fs::exists("/etc/exherbo-release", Exists) && Exists)
    return Exherbo;

  if (!llvm::sys::fs::exists("/etc/arch-release", Exists) && Exists)
    return ArchLinux;

  return UnknownDistro;
}

/// \brief Trivial helper function to simplify code checking path existence.
static bool PathExists(StringRef Path) {
  bool Exists;
  if (!llvm::sys::fs::exists(Path, Exists))
    return Exists;
  return false;
}

namespace {
/// \brief This is a class to find a viable GCC installation for Clang to use.
///
/// This class tries to find a GCC installation on the system, and report
/// information about it. It starts from the host information provided to the
/// Driver, and has logic for fuzzing that where appropriate.
class GCCInstallationDetector {
  /// \brief Struct to store and manipulate GCC versions.
  ///
  /// We rely on assumptions about the form and structure of GCC version
  /// numbers: they consist of at most three '.'-separated components, and each
  /// component is a non-negative integer.
  struct GCCVersion {
    unsigned Major, Minor, Patch;

    static GCCVersion Parse(StringRef VersionText) {
      const GCCVersion BadVersion = {};
      std::pair<StringRef, StringRef> First = VersionText.split('.');
      std::pair<StringRef, StringRef> Second = First.second.split('.');

      GCCVersion GoodVersion = {};
      if (First.first.getAsInteger(10, GoodVersion.Major))
        return BadVersion;
      if (Second.first.getAsInteger(10, GoodVersion.Minor))
        return BadVersion;
      // We accept a number, or a string for the patch version, in case there
      // is a strang suffix, or other mangling: '4.1.x', '4.1.2-rc3'. When it
      // isn't a number, we just use '0' as the number but accept it.
      if (Second.first.getAsInteger(10, GoodVersion.Patch))
        GoodVersion.Patch = 0;
      return GoodVersion;
    }

    bool operator<(const GCCVersion &RHS) const {
      if (Major < RHS.Major) return true;
      if (Major > RHS.Major) return false;
      if (Minor < RHS.Minor) return true;
      if (Minor > RHS.Minor) return false;
      return Patch < RHS.Patch;
    }
    bool operator>(const GCCVersion &RHS) const { return RHS < *this; }
    bool operator<=(const GCCVersion &RHS) const { return !(*this > RHS); }
    bool operator>=(const GCCVersion &RHS) const { return !(*this < RHS); }
  };

  bool IsValid;
  std::string GccTriple;

  // FIXME: These might be better as path objects.
  std::string GccInstallPath;
  std::string GccParentLibPath;

  llvm::SmallString<128> CxxIncludeRoot;

public:
  /// \brief Construct a GCCInstallationDetector from the driver.
  ///
  /// This performs all of the autodetection and sets up the various paths.
  /// Once constructed, a GCCInstallation is esentially immutable.
  GCCInstallationDetector(const Driver &D)
    : IsValid(false),
      GccTriple(D.DefaultHostTriple),
      CxxIncludeRoot(CXX_INCLUDE_ROOT) {
    // FIXME: Using CXX_INCLUDE_ROOT is here is a bit of a hack, but
    // avoids adding yet another option to configure/cmake.
    // It would probably be cleaner to break it in two variables
    // CXX_GCC_ROOT with just /foo/bar
    // CXX_GCC_VER with 4.5.2
    // Then we would have
    // CXX_INCLUDE_ROOT = CXX_GCC_ROOT/include/c++/CXX_GCC_VER
    // and this function would return
    // CXX_GCC_ROOT/lib/gcc/CXX_INCLUDE_ARCH/CXX_GCC_VER
    if (CxxIncludeRoot != "") {
      // This is of the form /foo/bar/include/c++/4.5.2/
      if (CxxIncludeRoot.back() == '/')
        llvm::sys::path::remove_filename(CxxIncludeRoot); // remove the /
      StringRef Version = llvm::sys::path::filename(CxxIncludeRoot);
      llvm::sys::path::remove_filename(CxxIncludeRoot); // remove the version
      llvm::sys::path::remove_filename(CxxIncludeRoot); // remove the c++
      llvm::sys::path::remove_filename(CxxIncludeRoot); // remove the include
      GccInstallPath = CxxIncludeRoot.str();
      GccInstallPath.append("/lib/gcc/");
      GccInstallPath.append(CXX_INCLUDE_ARCH);
      GccInstallPath.append("/");
      GccInstallPath.append(Version);
      GccParentLibPath = GccInstallPath + "/../../../..";
      IsValid = true;
      return;
    }

    llvm::Triple::ArchType HostArch = llvm::Triple(GccTriple).getArch();
    // The library directories which may contain GCC installations.
    SmallVector<StringRef, 4> CandidateLibDirs;
    // The compatible GCC triples for this particular architecture.
    SmallVector<StringRef, 10> CandidateTriples;
    CollectLibDirsAndTriples(HostArch, CandidateLibDirs, CandidateTriples);

    // Always include the default host triple as the final fallback if no
    // specific triple is detected.
    CandidateTriples.push_back(D.DefaultHostTriple);

    // Compute the set of prefixes for our search.
    SmallVector<std::string, 8> Prefixes(D.PrefixDirs.begin(),
                                         D.PrefixDirs.end());
    Prefixes.push_back(D.SysRoot);
    Prefixes.push_back(D.SysRoot + "/usr");
    Prefixes.push_back(D.InstalledDir + "/..");

    // Loop over the various components which exist and select the best GCC
    // installation available. GCC installs are ranked by version number.
    GCCVersion BestVersion = {};
    for (unsigned i = 0, ie = Prefixes.size(); i < ie; ++i) {
      if (!PathExists(Prefixes[i]))
        continue;
      for (unsigned j = 0, je = CandidateLibDirs.size(); j < je; ++j) {
        const std::string LibDir = Prefixes[i] + CandidateLibDirs[j].str();
        if (!PathExists(LibDir))
          continue;
        for (unsigned k = 0, ke = CandidateTriples.size(); k < ke; ++k)
          ScanLibDirForGCCTriple(LibDir, CandidateTriples[k], BestVersion);
      }
    }
  }

  /// \brief Check whether we detected a valid GCC install.
  bool isValid() const { return IsValid; }

  /// \brief Get the GCC triple for the detected install.
  const std::string &getTriple() const { return GccTriple; }

  /// \brief Get the detected GCC installation path.
  const std::string &getInstallPath() const { return GccInstallPath; }

  /// \brief Get the detected GCC parent lib path.
  const std::string &getParentLibPath() const { return GccParentLibPath; }

private:
  static void CollectLibDirsAndTriples(llvm::Triple::ArchType HostArch,
                                       SmallVectorImpl<StringRef> &LibDirs,
                                       SmallVectorImpl<StringRef> &Triples) {
    if (HostArch == llvm::Triple::arm || HostArch == llvm::Triple::thumb) {
      static const char *const ARMLibDirs[] = { "/lib/gcc" };
      static const char *const ARMTriples[] = { "arm-linux-gnueabi" };
      LibDirs.append(ARMLibDirs, ARMLibDirs + llvm::array_lengthof(ARMLibDirs));
      Triples.append(ARMTriples, ARMTriples + llvm::array_lengthof(ARMTriples));
    } else if (HostArch == llvm::Triple::x86_64) {
      static const char *const X86_64LibDirs[] = {
        "/lib64/gcc", "/lib/gcc", "/lib64", "/lib"
      };
      static const char *const X86_64Triples[] = {
        "x86_64-linux-gnu",
        "x86_64-unknown-linux-gnu",
        "x86_64-pc-linux-gnu",
        "x86_64-redhat-linux6E",
        "x86_64-redhat-linux",
        "x86_64-suse-linux",
        "x86_64-manbo-linux-gnu",
        "x86_64-linux-gnu",
        "x86_64-slackware-linux"
      };
      LibDirs.append(X86_64LibDirs,
                     X86_64LibDirs + llvm::array_lengthof(X86_64LibDirs));
      Triples.append(X86_64Triples,
                     X86_64Triples + llvm::array_lengthof(X86_64Triples));
    } else if (HostArch == llvm::Triple::x86) {
      static const char *const X86LibDirs[] = {
        "/lib32/gcc", "/lib/gcc", "/lib32", "/lib"
      };
      static const char *const X86Triples[] = {
        "i686-linux-gnu",
        "i386-linux-gnu",
        "i686-pc-linux-gnu",
        "i486-linux-gnu",
        "i686-redhat-linux",
        "i586-suse-linux",
        "i486-slackware-linux"
      };
      LibDirs.append(X86LibDirs, X86LibDirs + llvm::array_lengthof(X86LibDirs));
      Triples.append(X86Triples, X86Triples + llvm::array_lengthof(X86Triples));
    } else if (HostArch == llvm::Triple::ppc) {
      static const char *const PPCLibDirs[] = {
        "/lib32/gcc", "/lib/gcc", "/lib32", "/lib"
      };
      static const char *const PPCTriples[] = {
        "powerpc-linux-gnu",
        "powerpc-unknown-linux-gnu"
      };
      LibDirs.append(PPCLibDirs, PPCLibDirs + llvm::array_lengthof(PPCLibDirs));
      Triples.append(PPCTriples, PPCTriples + llvm::array_lengthof(PPCTriples));
    } else if (HostArch == llvm::Triple::ppc64) {
      static const char *const PPC64LibDirs[] = {
        "/lib64/gcc", "/lib/gcc", "/lib64", "/lib"
      };
      static const char *const PPC64Triples[] = {
        "powerpc64-unknown-linux-gnu"
      };
      LibDirs.append(PPC64LibDirs,
                     PPC64LibDirs + llvm::array_lengthof(PPC64LibDirs));
      Triples.append(PPC64Triples,
                     PPC64Triples + llvm::array_lengthof(PPC64Triples));
    }
  }

  void ScanLibDirForGCCTriple(const std::string &LibDir,
                              StringRef CandidateTriple,
                              GCCVersion &BestVersion) {
    const std::string TripleDir = LibDir + "/" + CandidateTriple.str();
    if (!PathExists(TripleDir))
      return;

    // There are various different suffixes on the triple directory we
    // check for. We also record what is necessary to walk from each back
    // up to the lib directory.
    const std::string Suffixes[] = { "", "/gcc/" + CandidateTriple.str(),
      "/gcc/i686-linux-gnu" };
    const std::string InstallSuffixes[] = { "/../../..", "/../../../..",
      "/../../../.." };
    const unsigned NumSuffixes = (llvm::array_lengthof(Suffixes) -
                                  (CandidateTriple != "i386-linux-gnu"));
    for (unsigned i = 0; i < NumSuffixes; ++i) {
      StringRef Suffix = Suffixes[i];
      llvm::error_code EC;
      for (llvm::sys::fs::directory_iterator LI(TripleDir + Suffix, EC), LE;
           !EC && LI != LE; LI = LI.increment(EC)) {
        StringRef VersionText = llvm::sys::path::filename(LI->path());
        GCCVersion CandidateVersion = GCCVersion::Parse(VersionText);
        static const GCCVersion MinVersion = { 4, 1, 1 };
        if (CandidateVersion < MinVersion)
          continue;
        if (CandidateVersion <= BestVersion)
          continue;
        if (!PathExists(LI->path() + "/crtbegin.o"))
          continue;

        BestVersion = CandidateVersion;
        GccTriple = CandidateTriple.str();
        // FIXME: We hack together the directory name here instead of
        // using LI to ensure stable path separators across Windows and
        // Linux.
        GccInstallPath = TripleDir + Suffixes[i] + "/" + VersionText.str();
        GccParentLibPath = GccInstallPath + InstallSuffixes[i];
        IsValid = true;
      }
    }
  }
};
}

static void addPathIfExists(const std::string &Path,
                            ToolChain::path_list &Paths) {
  if (PathExists(Path)) Paths.push_back(Path);
}

Linux::Linux(const HostInfo &Host, const llvm::Triple &Triple)
  : Generic_ELF(Host, Triple) {
  llvm::Triple::ArchType Arch =
    llvm::Triple(getDriver().DefaultHostTriple).getArch();
  const std::string &SysRoot = getDriver().SysRoot;
  GCCInstallationDetector GCCInstallation(getDriver());

  // OpenSuse stores the linker with the compiler, add that to the search
  // path.
  ToolChain::path_list &PPaths = getProgramPaths();
  PPaths.push_back(GCCInstallation.getParentLibPath() + "/../" +
                   GCCInstallation.getTriple() + "/bin");

  Linker = GetProgramPath("ld");

  LinuxDistro Distro = DetectLinuxDistro(Arch);

  if (IsOpenSuse(Distro) || IsUbuntu(Distro)) {
    ExtraOpts.push_back("-z");
    ExtraOpts.push_back("relro");
  }

  if (Arch == llvm::Triple::arm || Arch == llvm::Triple::thumb)
    ExtraOpts.push_back("-X");

  if (IsRedhat(Distro) || IsOpenSuse(Distro) || Distro == UbuntuMaverick ||
      Distro == UbuntuNatty || Distro == UbuntuOneiric)
    ExtraOpts.push_back("--hash-style=gnu");

  if (IsDebian(Distro) || IsOpenSuse(Distro) || Distro == UbuntuLucid ||
      Distro == UbuntuJaunty || Distro == UbuntuKarmic)
    ExtraOpts.push_back("--hash-style=both");

  if (IsRedhat(Distro))
    ExtraOpts.push_back("--no-add-needed");

  if (Distro == DebianSqueeze || Distro == DebianWheezy ||
      IsOpenSuse(Distro) ||
      (IsRedhat(Distro) && Distro != RHEL4 && Distro != RHEL5) ||
      Distro == UbuntuLucid ||
      Distro == UbuntuMaverick || Distro == UbuntuKarmic ||
      Distro == UbuntuNatty || Distro == UbuntuOneiric)
    ExtraOpts.push_back("--build-id");

  if (IsOpenSuse(Distro))
    ExtraOpts.push_back("--enable-new-dtags");

  // The selection of paths to try here is designed to match the patterns which
  // the GCC driver itself uses, as this is part of the GCC-compatible driver.
  // This was determined by running GCC in a fake filesystem, creating all
  // possible permutations of these directories, and seeing which ones it added
  // to the link paths.
  path_list &Paths = getFilePaths();
  const bool Is32Bits = (getArch() == llvm::Triple::x86 ||
                         getArch() == llvm::Triple::ppc);

  const std::string Suffix32 = Arch == llvm::Triple::x86_64 ? "/32" : "";
  const std::string Suffix64 = Arch == llvm::Triple::x86_64 ? "" : "/64";
  const std::string Suffix = Is32Bits ? Suffix32 : Suffix64;
  const std::string Multilib = Is32Bits ? "lib32" : "lib64";

  // FIXME: Because we add paths only when they exist on the system, I think we
  // should remove the concept of 'HasMultilib'. It's more likely to break the
  // behavior than to preserve any useful invariant on the system.
  if (HasMultilib(Arch, Distro)) {
    // Add the multilib suffixed paths.
    if (GCCInstallation.isValid()) {
      const std::string &LibPath = GCCInstallation.getParentLibPath();
      const std::string &GccTriple = GCCInstallation.getTriple();
      // FIXME: This OpenSuse-specific path shouldn't be needed any more, but
      // I don't want to remove it without finding someone to test.
      if (IsOpenSuse(Distro) && Is32Bits)
        Paths.push_back(LibPath + "/../" + GccTriple + "/lib/../lib");

      addPathIfExists(GCCInstallation.getInstallPath() + Suffix, Paths);
      addPathIfExists(LibPath + "/../" + GccTriple + "/lib/../" + Multilib,
                      Paths);
      addPathIfExists(LibPath + "/../" + Multilib, Paths);
    }
    addPathIfExists(SysRoot + "/lib/../" + Multilib, Paths);
    addPathIfExists(SysRoot + "/usr/lib/../" + Multilib, Paths);
  }

  // Add the non-multiplib suffixed paths (if potentially different).
  if (GCCInstallation.isValid()) {
    const std::string &LibPath = GCCInstallation.getParentLibPath();
    const std::string &GccTriple = GCCInstallation.getTriple();
    if (!Suffix.empty() || !HasMultilib(Arch, Distro))
      addPathIfExists(GCCInstallation.getInstallPath(), Paths);
    addPathIfExists(LibPath + "/../" + GccTriple + "/lib", Paths);
    addPathIfExists(LibPath, Paths);
  }
  addPathIfExists(SysRoot + "/lib", Paths);
  addPathIfExists(SysRoot + "/usr/lib", Paths);

  if (GCCInstallation.isValid() && Arch == getArch() && IsUbuntu(Distro))
    Paths.push_back(SysRoot + "/usr/lib/" + GCCInstallation.getTriple());
}

bool Linux::HasNativeLLVMSupport() const {
  return true;
}

Tool &Linux::SelectTool(const Compilation &C, const JobAction &JA,
                        const ActionList &Inputs) const {
  Action::ActionClass Key;
  if (getDriver().ShouldUseClangCompiler(C, JA, getTriple()))
    Key = Action::AnalyzeJobClass;
  else
    Key = JA.getKind();

  bool UseIntegratedAs = C.getArgs().hasFlag(options::OPT_integrated_as,
                                             options::OPT_no_integrated_as,
                                             IsIntegratedAssemblerDefault());

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::AssembleJobClass:
      if (UseIntegratedAs)
        T = new tools::ClangAs(*this);
      else
        T = new tools::linuxtools::Assemble(*this);
      break;
    case Action::LinkJobClass:
      T = new tools::linuxtools::Link(*this); break;
    default:
      T = &Generic_GCC::SelectTool(C, JA, Inputs);
    }
  }

  return *T;
}

/// DragonFly - DragonFly tool chain which can call as(1) and ld(1) directly.

DragonFly::DragonFly(const HostInfo &Host, const llvm::Triple& Triple)
  : Generic_ELF(Host, Triple) {

  // Path mangling to find libexec
  getProgramPaths().push_back(getDriver().getInstalledDir());
  if (getDriver().getInstalledDir() != getDriver().Dir)
    getProgramPaths().push_back(getDriver().Dir);

  getFilePaths().push_back(getDriver().Dir + "/../lib");
  getFilePaths().push_back("/usr/lib");
  getFilePaths().push_back("/usr/lib/gcc41");
}

Tool &DragonFly::SelectTool(const Compilation &C, const JobAction &JA,
                            const ActionList &Inputs) const {
  Action::ActionClass Key;
  if (getDriver().ShouldUseClangCompiler(C, JA, getTriple()))
    Key = Action::AnalyzeJobClass;
  else
    Key = JA.getKind();

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::AssembleJobClass:
      T = new tools::dragonfly::Assemble(*this); break;
    case Action::LinkJobClass:
      T = new tools::dragonfly::Link(*this); break;
    default:
      T = &Generic_GCC::SelectTool(C, JA, Inputs);
    }
  }

  return *T;
}

Windows::Windows(const HostInfo &Host, const llvm::Triple& Triple)
  : ToolChain(Host, Triple) {
}

Tool &Windows::SelectTool(const Compilation &C, const JobAction &JA,
                          const ActionList &Inputs) const {
  Action::ActionClass Key;
  if (getDriver().ShouldUseClangCompiler(C, JA, getTriple()))
    Key = Action::AnalyzeJobClass;
  else
    Key = JA.getKind();

  bool UseIntegratedAs = C.getArgs().hasFlag(options::OPT_integrated_as,
                                             options::OPT_no_integrated_as,
                                             IsIntegratedAssemblerDefault());

  Tool *&T = Tools[Key];
  if (!T) {
    switch (Key) {
    case Action::InputClass:
    case Action::BindArchClass:
    case Action::LipoJobClass:
    case Action::DsymutilJobClass:
    case Action::VerifyJobClass:
      llvm_unreachable("Invalid tool kind.");
    case Action::PreprocessJobClass:
    case Action::PrecompileJobClass:
    case Action::AnalyzeJobClass:
    case Action::CompileJobClass:
      T = new tools::Clang(*this); break;
    case Action::AssembleJobClass:
      if (!UseIntegratedAs && getTriple().getEnvironment() == llvm::Triple::MachO)
        T = new tools::darwin::Assemble(*this);
      else
        T = new tools::ClangAs(*this);
      break;
    case Action::LinkJobClass:
      T = new tools::visualstudio::Link(*this); break;
    }
  }

  return *T;
}

bool Windows::IsIntegratedAssemblerDefault() const {
  return true;
}

bool Windows::IsUnwindTablesDefault() const {
  // FIXME: Gross; we should probably have some separate target
  // definition, possibly even reusing the one in clang.
  return getArchName() == "x86_64";
}

const char *Windows::GetDefaultRelocationModel() const {
  return "static";
}

const char *Windows::GetForcedPicModel() const {
  if (getArchName() == "x86_64")
    return "pic";
  return 0;
}