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

#include "ToolChains.h"
#include "clang/Basic/Cuda.h"
#include "clang/Basic/ObjCRuntime.h"
#include "clang/Basic/Version.h"
#include "clang/Basic/VirtualFileSystem.h"
#include "clang/Config/config.h" // for GCC_INSTALL_PREFIX
#include "clang/Driver/Compilation.h"
#include "clang/Driver/Distro.h"
#include "clang/Driver/Driver.h"
#include "clang/Driver/DriverDiagnostic.h"
#include "clang/Driver/Options.h"
#include "clang/Driver/SanitizerArgs.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Option/Arg.h"
#include "llvm/Option/ArgList.h"
#include "llvm/Option/OptTable.h"
#include "llvm/Option/Option.h"
#include "llvm/ProfileData/InstrProf.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Program.h"
#include "llvm/Support/TargetParser.h"
#include "llvm/Support/raw_ostream.h"
#include <cstdlib> // ::getenv
#include <system_error>

using namespace clang::driver;
using namespace clang::driver::toolchains;
using namespace clang;
using namespace llvm::opt;

MachO::MachO(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
    : ToolChain(D, Triple, Args) {
  // 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);
}

/// Darwin - Darwin tool chain for i386 and x86_64.
Darwin::Darwin(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
    : MachO(D, Triple, Args), TargetInitialized(false),
      CudaInstallation(D, Triple, Args) {}

types::ID MachO::LookupTypeForExtension(StringRef 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 MachO::HasNativeLLVMSupport() const { return true; }

ToolChain::CXXStdlibType Darwin::GetDefaultCXXStdlibType() const {
  // Default to use libc++ on OS X 10.9+ and iOS 7+.
  if ((isTargetMacOS() && !isMacosxVersionLT(10, 9)) ||
       (isTargetIOSBased() && !isIPhoneOSVersionLT(7, 0)) ||
       isTargetWatchOSBased())
    return ToolChain::CST_Libcxx;

  return ToolChain::CST_Libstdcxx;
}

/// Darwin provides an ARC runtime starting in MacOS X 10.7 and iOS 5.0.
ObjCRuntime Darwin::getDefaultObjCRuntime(bool isNonFragile) const {
  if (isTargetWatchOSBased())
    return ObjCRuntime(ObjCRuntime::WatchOS, TargetVersion);
  if (isTargetIOSBased())
    return ObjCRuntime(ObjCRuntime::iOS, TargetVersion);
  if (isNonFragile)
    return ObjCRuntime(ObjCRuntime::MacOSX, TargetVersion);
  return ObjCRuntime(ObjCRuntime::FragileMacOSX, TargetVersion);
}

/// Darwin provides a blocks runtime starting in MacOS X 10.6 and iOS 3.2.
bool Darwin::hasBlocksRuntime() const {
  if (isTargetWatchOSBased())
    return true;
  else if (isTargetIOSBased())
    return !isIPhoneOSVersionLT(3, 2);
  else {
    assert(isTargetMacOS() && "unexpected darwin target");
    return !isMacosxVersionLT(10, 6);
  }
}

void Darwin::AddCudaIncludeArgs(const ArgList &DriverArgs,
                                ArgStringList &CC1Args) const {
  CudaInstallation.AddCudaIncludeArgs(DriverArgs, CC1Args);
}

// This is just a MachO name translation routine and there's no
// way to join this into ARMTargetParser without breaking all
// other assumptions. Maybe MachO should consider standardising
// their nomenclature.
static const char *ArmMachOArchName(StringRef Arch) {
  return llvm::StringSwitch<const char *>(Arch)
      .Case("armv6k", "armv6")
      .Case("armv6m", "armv6m")
      .Case("armv5tej", "armv5")
      .Case("xscale", "xscale")
      .Case("armv4t", "armv4t")
      .Case("armv7", "armv7")
      .Cases("armv7a", "armv7-a", "armv7")
      .Cases("armv7r", "armv7-r", "armv7")
      .Cases("armv7em", "armv7e-m", "armv7em")
      .Cases("armv7k", "armv7-k", "armv7k")
      .Cases("armv7m", "armv7-m", "armv7m")
      .Cases("armv7s", "armv7-s", "armv7s")
      .Default(nullptr);
}

static const char *ArmMachOArchNameCPU(StringRef CPU) {
  unsigned ArchKind = llvm::ARM::parseCPUArch(CPU);
  if (ArchKind == llvm::ARM::AK_INVALID)
    return nullptr;
  StringRef Arch = llvm::ARM::getArchName(ArchKind);

  // FIXME: Make sure this MachO triple mangling is really necessary.
  // ARMv5* normalises to ARMv5.
  if (Arch.startswith("armv5"))
    Arch = Arch.substr(0, 5);
  // ARMv6*, except ARMv6M, normalises to ARMv6.
  else if (Arch.startswith("armv6") && !Arch.endswith("6m"))
    Arch = Arch.substr(0, 5);
  // ARMv7A normalises to ARMv7.
  else if (Arch.endswith("v7a"))
    Arch = Arch.substr(0, 5);
  return Arch.data();
}

static bool isSoftFloatABI(const ArgList &Args) {
  Arg *A = Args.getLastArg(options::OPT_msoft_float, options::OPT_mhard_float,
                           options::OPT_mfloat_abi_EQ);
  if (!A)
    return false;

  return A->getOption().matches(options::OPT_msoft_float) ||
         (A->getOption().matches(options::OPT_mfloat_abi_EQ) &&
          A->getValue() == StringRef("soft"));
}

StringRef MachO::getMachOArchName(const ArgList &Args) const {
  switch (getTriple().getArch()) {
  default:
    return getDefaultUniversalArchName();

  case llvm::Triple::aarch64:
    return "arm64";

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

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

    return "arm";
  }
}

Darwin::~Darwin() {}

MachO::~MachO() {}

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();

  SmallString<16> Str;
  if (isTargetWatchOSBased())
    Str += "watchos";
  else if (isTargetTvOSBased())
    Str += "tvos";
  else if (isTargetIOSBased())
    Str += "ios";
  else
    Str += "macosx";
  Str += getTargetVersion().getAsString();
  Triple.setOSName(Str);

  return Triple.getTriple();
}

void Generic_ELF::anchor() {}

Tool *MachO::getTool(Action::ActionClass AC) const {
  switch (AC) {
  case Action::LipoJobClass:
    if (!Lipo)
      Lipo.reset(new tools::darwin::Lipo(*this));
    return Lipo.get();
  case Action::DsymutilJobClass:
    if (!Dsymutil)
      Dsymutil.reset(new tools::darwin::Dsymutil(*this));
    return Dsymutil.get();
  case Action::VerifyDebugInfoJobClass:
    if (!VerifyDebug)
      VerifyDebug.reset(new tools::darwin::VerifyDebug(*this));
    return VerifyDebug.get();
  default:
    return ToolChain::getTool(AC);
  }
}

Tool *MachO::buildLinker() const { return new tools::darwin::Linker(*this); }

Tool *MachO::buildAssembler() const {
  return new tools::darwin::Assembler(*this);
}

DarwinClang::DarwinClang(const Driver &D, const llvm::Triple &Triple,
                         const ArgList &Args)
    : Darwin(D, Triple, Args) {}

void DarwinClang::addClangWarningOptions(ArgStringList &CC1Args) const {
  // For modern targets, promote certain warnings to errors.
  if (isTargetWatchOSBased() || getTriple().isArch64Bit()) {
    // Always enable -Wdeprecated-objc-isa-usage and promote it
    // to an error.
    CC1Args.push_back("-Wdeprecated-objc-isa-usage");
    CC1Args.push_back("-Werror=deprecated-objc-isa-usage");

    // For iOS and watchOS, also error about implicit function declarations,
    // as that can impact calling conventions.
    if (!isTargetMacOS())
      CC1Args.push_back("-Werror=implicit-function-declaration");
  }
}

/// \brief Determine whether Objective-C automated reference counting is
/// enabled.
static bool isObjCAutoRefCount(const ArgList &Args) {
  return Args.hasFlag(options::OPT_fobjc_arc, options::OPT_fno_objc_arc, false);
}

void DarwinClang::AddLinkARCArgs(const ArgList &Args,
                                 ArgStringList &CmdArgs) const {
  // Avoid linking compatibility stubs on i386 mac.
  if (isTargetMacOS() && getArch() == llvm::Triple::x86)
    return;

  ObjCRuntime runtime = getDefaultObjCRuntime(/*nonfragile*/ true);

  if ((runtime.hasNativeARC() || !isObjCAutoRefCount(Args)) &&
      runtime.hasSubscripting())
    return;

  CmdArgs.push_back("-force_load");
  SmallString<128> P(getDriver().ClangExecutable);
  llvm::sys::path::remove_filename(P); // 'clang'
  llvm::sys::path::remove_filename(P); // 'bin'
  llvm::sys::path::append(P, "lib", "arc", "libarclite_");
  // Mash in the platform.
  if (isTargetWatchOSSimulator())
    P += "watchsimulator";
  else if (isTargetWatchOS())
    P += "watchos";
  else if (isTargetTvOSSimulator())
    P += "appletvsimulator";
  else if (isTargetTvOS())
    P += "appletvos";
  else if (isTargetIOSSimulator())
    P += "iphonesimulator";
  else if (isTargetIPhoneOS())
    P += "iphoneos";
  else
    P += "macosx";
  P += ".a";

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

unsigned DarwinClang::GetDefaultDwarfVersion() const {
  // Default to use DWARF 2 on OS X 10.10 / iOS 8 and lower.
  if ((isTargetMacOS() && isMacosxVersionLT(10, 11)) ||
      (isTargetIOSBased() && isIPhoneOSVersionLT(9)))
    return 2;
  return 4;
}

void MachO::AddLinkRuntimeLib(const ArgList &Args, ArgStringList &CmdArgs,
                              StringRef DarwinLibName, bool AlwaysLink,
                              bool IsEmbedded, bool AddRPath) const {
  SmallString<128> Dir(getDriver().ResourceDir);
  llvm::sys::path::append(Dir, "lib", IsEmbedded ? "macho_embedded" : "darwin");

  SmallString<128> P(Dir);
  llvm::sys::path::append(P, DarwinLibName);

  // For now, allow missing resource libraries to support developers who may
  // not have compiler-rt checked out or integrated into their build (unless
  // we explicitly force linking with this library).
  if (AlwaysLink || getVFS().exists(P))
    CmdArgs.push_back(Args.MakeArgString(P));

  // Adding the rpaths might negatively interact when other rpaths are involved,
  // so we should make sure we add the rpaths last, after all user-specified
  // rpaths. This is currently true from this place, but we need to be
  // careful if this function is ever called before user's rpaths are emitted.
  if (AddRPath) {
    assert(DarwinLibName.endswith(".dylib") && "must be a dynamic library");

    // Add @executable_path to rpath to support having the dylib copied with
    // the executable.
    CmdArgs.push_back("-rpath");
    CmdArgs.push_back("@executable_path");

    // Add the path to the resource dir to rpath to support using the dylib
    // from the default location without copying.
    CmdArgs.push_back("-rpath");
    CmdArgs.push_back(Args.MakeArgString(Dir));
  }
}

StringRef Darwin::getPlatformFamily() const {
  switch (TargetPlatform) {
    case DarwinPlatformKind::MacOS:
      return "MacOSX";
    case DarwinPlatformKind::IPhoneOS:
    case DarwinPlatformKind::IPhoneOSSimulator:
      return "iPhone";
    case DarwinPlatformKind::TvOS:
    case DarwinPlatformKind::TvOSSimulator:
      return "AppleTV";
    case DarwinPlatformKind::WatchOS:
    case DarwinPlatformKind::WatchOSSimulator:
      return "Watch";
  }
  llvm_unreachable("Unsupported platform");
}

StringRef Darwin::getSDKName(StringRef isysroot) {
  // Assume SDK has path: SOME_PATH/SDKs/PlatformXX.YY.sdk
  llvm::sys::path::const_iterator SDKDir;
  auto BeginSDK = llvm::sys::path::begin(isysroot);
  auto EndSDK = llvm::sys::path::end(isysroot);
  for (auto IT = BeginSDK; IT != EndSDK; ++IT) {
    StringRef SDK = *IT;
    if (SDK.endswith(".sdk"))
      return SDK.slice(0, SDK.size() - 4);
  }
  return "";
}

StringRef Darwin::getOSLibraryNameSuffix() const {
  switch(TargetPlatform) {
  case DarwinPlatformKind::MacOS:
    return "osx";
  case DarwinPlatformKind::IPhoneOS:
    return "ios";
  case DarwinPlatformKind::IPhoneOSSimulator:
    return "iossim";
  case DarwinPlatformKind::TvOS:
    return "tvos";
  case DarwinPlatformKind::TvOSSimulator:
    return "tvossim";
  case DarwinPlatformKind::WatchOS:
    return "watchos";
  case DarwinPlatformKind::WatchOSSimulator:
    return "watchossim";
  }
  llvm_unreachable("Unsupported platform");
}

void Darwin::addProfileRTLibs(const ArgList &Args,
                              ArgStringList &CmdArgs) const {
  if (!needsProfileRT(Args)) return;

  AddLinkRuntimeLib(Args, CmdArgs, (Twine("libclang_rt.profile_") +
       getOSLibraryNameSuffix() + ".a").str(),
                    /*AlwaysLink*/ true);
}

void DarwinClang::AddLinkSanitizerLibArgs(const ArgList &Args,
                                          ArgStringList &CmdArgs,
                                          StringRef Sanitizer) const {
  AddLinkRuntimeLib(
      Args, CmdArgs,
      (Twine("libclang_rt.") + Sanitizer + "_" +
       getOSLibraryNameSuffix() + "_dynamic.dylib").str(),
      /*AlwaysLink*/ true, /*IsEmbedded*/ false,
      /*AddRPath*/ true);
}

ToolChain::RuntimeLibType DarwinClang::GetRuntimeLibType(
    const ArgList &Args) const {
  if (Arg* A = Args.getLastArg(options::OPT_rtlib_EQ)) {
    StringRef Value = A->getValue();
    if (Value != "compiler-rt")
      getDriver().Diag(diag::err_drv_unsupported_rtlib_for_platform)
          << Value << "darwin";
  }

  return ToolChain::RLT_CompilerRT;
}

void DarwinClang::AddLinkRuntimeLibArgs(const ArgList &Args,
                                        ArgStringList &CmdArgs) const {
  // Call once to ensure diagnostic is printed if wrong value was specified
  GetRuntimeLibType(Args);

  // Darwin doesn't support real static executables, don't link any runtime
  // libraries with -static.
  if (Args.hasArg(options::OPT_static) ||
      Args.hasArg(options::OPT_fapple_kext) ||
      Args.hasArg(options::OPT_mkernel))
    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;
  }

  const SanitizerArgs &Sanitize = getSanitizerArgs();
  if (Sanitize.needsAsanRt())
    AddLinkSanitizerLibArgs(Args, CmdArgs, "asan");
  if (Sanitize.needsUbsanRt())
    AddLinkSanitizerLibArgs(Args, CmdArgs, "ubsan");
  if (Sanitize.needsTsanRt())
    AddLinkSanitizerLibArgs(Args, CmdArgs, "tsan");
  if (Sanitize.needsStatsRt()) {
    StringRef OS = isTargetMacOS() ? "osx" : "iossim";
    AddLinkRuntimeLib(Args, CmdArgs,
                      (Twine("libclang_rt.stats_client_") + OS + ".a").str(),
                      /*AlwaysLink=*/true);
    AddLinkSanitizerLibArgs(Args, CmdArgs, "stats");
  }
  if (Sanitize.needsEsanRt())
    AddLinkSanitizerLibArgs(Args, CmdArgs, "esan");

  // 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 (isTargetWatchOSBased()) {
    // We currently always need a static runtime library for watchOS.
    AddLinkRuntimeLib(Args, CmdArgs, "libclang_rt.watchos.a");
  } else if (isTargetTvOSBased()) {
    // We currently always need a static runtime library for tvOS.
    AddLinkRuntimeLib(Args, CmdArgs, "libclang_rt.tvos.a");
  } else if (isTargetIOSBased()) {
    // If we are compiling as iOS / simulator, don't attempt to link libgcc_s.1,
    // it never went into the SDK.
    // Linking against libgcc_s.1 isn't needed for iOS 5.0+
    if (isIPhoneOSVersionLT(5, 0) && !isTargetIOSSimulator() &&
        getTriple().getArch() != llvm::Triple::aarch64)
      CmdArgs.push_back("-lgcc_s.1");

    // We currently always need a static runtime library for iOS.
    AddLinkRuntimeLib(Args, CmdArgs, "libclang_rt.ios.a");
  } else {
    assert(isTargetMacOS() && "unexpected non MacOS platform");
    // 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");

    // Originally 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. This led to the creation of the 10.4
    // builtins library.
    //
    // 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.
    //
    // Then over time, we figured out it was useful to add more things to the
    // runtime so we created libclang_rt.osx.a to provide new functions when
    // deploying to old OS builds, and for a long time we had both eprintf and
    // osx builtin libraries. Which just seems excessive. So with PR 28855, we
    // are removing the eprintf library and expecting eprintf to be provided by
    // the OS X builtins library.
    if (isMacosxVersionLT(10, 5))
      AddLinkRuntimeLib(Args, CmdArgs, "libclang_rt.10.4.a");
    else
      AddLinkRuntimeLib(Args, CmdArgs, "libclang_rt.osx.a");
  }
}

/// Returns the most appropriate macOS target version for the current process.
///
/// If the macOS SDK version is the same or earlier than the system version,
/// then the SDK version is returned. Otherwise the system version is returned.
static std::string getSystemOrSDKMacOSVersion(StringRef MacOSSDKVersion) {
  unsigned Major, Minor, Micro;
  llvm::Triple SystemTriple(llvm::sys::getProcessTriple());
  if (!SystemTriple.isMacOSX())
    return MacOSSDKVersion;
  SystemTriple.getMacOSXVersion(Major, Minor, Micro);
  VersionTuple SystemVersion(Major, Minor, Micro);
  bool HadExtra;
  if (!Driver::GetReleaseVersion(MacOSSDKVersion, Major, Minor, Micro,
                                 HadExtra))
    return MacOSSDKVersion;
  VersionTuple SDKVersion(Major, Minor, Micro);
  if (SDKVersion > SystemVersion)
    return SystemVersion.getAsString();
  return MacOSSDKVersion;
}

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

  // Support allowing the SDKROOT environment variable used by xcrun and other
  // Xcode tools to define the default sysroot, by making it the default for
  // isysroot.
  if (const Arg *A = Args.getLastArg(options::OPT_isysroot)) {
    // Warn if the path does not exist.
    if (!getVFS().exists(A->getValue()))
      getDriver().Diag(clang::diag::warn_missing_sysroot) << A->getValue();
  } else {
    if (char *env = ::getenv("SDKROOT")) {
      // We only use this value as the default if it is an absolute path,
      // exists, and it is not the root path.
      if (llvm::sys::path::is_absolute(env) && getVFS().exists(env) &&
          StringRef(env) != "/") {
        Args.append(Args.MakeSeparateArg(
            nullptr, Opts.getOption(options::OPT_isysroot), env));
      }
    }
  }

  Arg *OSXVersion = Args.getLastArg(options::OPT_mmacosx_version_min_EQ);
  Arg *iOSVersion = Args.getLastArg(options::OPT_miphoneos_version_min_EQ,
                                    options::OPT_mios_simulator_version_min_EQ);
  Arg *TvOSVersion =
      Args.getLastArg(options::OPT_mtvos_version_min_EQ,
                      options::OPT_mtvos_simulator_version_min_EQ);
  Arg *WatchOSVersion =
      Args.getLastArg(options::OPT_mwatchos_version_min_EQ,
                      options::OPT_mwatchos_simulator_version_min_EQ);

  // Add a macro to differentiate between m(iphone|tv|watch)os-version-min=X.Y and
  // -m(iphone|tv|watch)simulator-version-min=X.Y.
  if (Args.hasArg(options::OPT_mios_simulator_version_min_EQ) ||
      Args.hasArg(options::OPT_mtvos_simulator_version_min_EQ) ||
      Args.hasArg(options::OPT_mwatchos_simulator_version_min_EQ))
    Args.append(Args.MakeSeparateArg(nullptr, Opts.getOption(options::OPT_D),
                                     " __APPLE_EMBEDDED_SIMULATOR__=1"));

  if (OSXVersion && (iOSVersion || TvOSVersion || WatchOSVersion)) {
    getDriver().Diag(diag::err_drv_argument_not_allowed_with)
        << OSXVersion->getAsString(Args)
        << (iOSVersion ? iOSVersion :
            TvOSVersion ? TvOSVersion : WatchOSVersion)->getAsString(Args);
    iOSVersion = TvOSVersion = WatchOSVersion = nullptr;
  } else if (iOSVersion && (TvOSVersion || WatchOSVersion)) {
    getDriver().Diag(diag::err_drv_argument_not_allowed_with)
        << iOSVersion->getAsString(Args)
        << (TvOSVersion ? TvOSVersion : WatchOSVersion)->getAsString(Args);
    TvOSVersion = WatchOSVersion = nullptr;
  } else if (TvOSVersion && WatchOSVersion) {
     getDriver().Diag(diag::err_drv_argument_not_allowed_with)
        << TvOSVersion->getAsString(Args)
        << WatchOSVersion->getAsString(Args);
    WatchOSVersion = nullptr;
  } else if (!OSXVersion && !iOSVersion && !TvOSVersion && !WatchOSVersion) {
    // If no deployment target was specified on the command line, check for
    // environment defines.
    std::string OSXTarget;
    std::string iOSTarget;
    std::string TvOSTarget;
    std::string WatchOSTarget;

    if (char *env = ::getenv("MACOSX_DEPLOYMENT_TARGET"))
      OSXTarget = env;
    if (char *env = ::getenv("IPHONEOS_DEPLOYMENT_TARGET"))
      iOSTarget = env;
    if (char *env = ::getenv("TVOS_DEPLOYMENT_TARGET"))
      TvOSTarget = env;
    if (char *env = ::getenv("WATCHOS_DEPLOYMENT_TARGET"))
      WatchOSTarget = env;

    // If there is no command-line argument to specify the Target version and
    // no environment variable defined, see if we can set the default based
    // on -isysroot.
    if (OSXTarget.empty() && iOSTarget.empty() && WatchOSTarget.empty() &&
        TvOSTarget.empty() && Args.hasArg(options::OPT_isysroot)) {
      if (const Arg *A = Args.getLastArg(options::OPT_isysroot)) {
        StringRef isysroot = A->getValue();
        StringRef SDK = getSDKName(isysroot);
        if (SDK.size() > 0) {
          // Slice the version number out.
          // Version number is between the first and the last number.
          size_t StartVer = SDK.find_first_of("0123456789");
          size_t EndVer = SDK.find_last_of("0123456789");
          if (StartVer != StringRef::npos && EndVer > StartVer) {
            StringRef Version = SDK.slice(StartVer, EndVer + 1);
            if (SDK.startswith("iPhoneOS") ||
                SDK.startswith("iPhoneSimulator"))
              iOSTarget = Version;
            else if (SDK.startswith("MacOSX"))
              OSXTarget = getSystemOrSDKMacOSVersion(Version);
            else if (SDK.startswith("WatchOS") ||
                     SDK.startswith("WatchSimulator"))
              WatchOSTarget = Version;
            else if (SDK.startswith("AppleTVOS") ||
                     SDK.startswith("AppleTVSimulator"))
              TvOSTarget = Version;
          }
        }
      }
    }

    // If no OSX or iOS target has been specified, try to guess platform
    // from arch name and compute the version from the triple.
    if (OSXTarget.empty() && iOSTarget.empty() && TvOSTarget.empty() &&
        WatchOSTarget.empty()) {
      StringRef MachOArchName = getMachOArchName(Args);
      unsigned Major, Minor, Micro;
      if (MachOArchName == "armv7" || MachOArchName == "armv7s" ||
          MachOArchName == "arm64") {
        getTriple().getiOSVersion(Major, Minor, Micro);
        llvm::raw_string_ostream(iOSTarget) << Major << '.' << Minor << '.'
                                            << Micro;
      } else if (MachOArchName == "armv7k") {
        getTriple().getWatchOSVersion(Major, Minor, Micro);
        llvm::raw_string_ostream(WatchOSTarget) << Major << '.' << Minor << '.'
                                                << Micro;
      } else if (MachOArchName != "armv6m" && MachOArchName != "armv7m" &&
                 MachOArchName != "armv7em") {
        if (!getTriple().getMacOSXVersion(Major, Minor, Micro)) {
          getDriver().Diag(diag::err_drv_invalid_darwin_version)
              << getTriple().getOSName();
        }
        llvm::raw_string_ostream(OSXTarget) << Major << '.' << Minor << '.'
                                            << Micro;
      }
    }

    // Do not allow conflicts with the watchOS target.
    if (!WatchOSTarget.empty() && (!iOSTarget.empty() || !TvOSTarget.empty())) {
      getDriver().Diag(diag::err_drv_conflicting_deployment_targets)
        << "WATCHOS_DEPLOYMENT_TARGET"
        << (!iOSTarget.empty() ? "IPHONEOS_DEPLOYMENT_TARGET" :
            "TVOS_DEPLOYMENT_TARGET");
    }

    // Do not allow conflicts with the tvOS target.
    if (!TvOSTarget.empty() && !iOSTarget.empty()) {
      getDriver().Diag(diag::err_drv_conflicting_deployment_targets)
        << "TVOS_DEPLOYMENT_TARGET"
        << "IPHONEOS_DEPLOYMENT_TARGET";
    }

    // Allow conflicts among OSX and iOS for historical reasons, but choose the
    // default platform.
    if (!OSXTarget.empty() && (!iOSTarget.empty() ||
                               !WatchOSTarget.empty() ||
                               !TvOSTarget.empty())) {
      if (getTriple().getArch() == llvm::Triple::arm ||
          getTriple().getArch() == llvm::Triple::aarch64 ||
          getTriple().getArch() == llvm::Triple::thumb)
        OSXTarget = "";
      else
        iOSTarget = WatchOSTarget = TvOSTarget = "";
    }

    if (!OSXTarget.empty()) {
      const Option O = Opts.getOption(options::OPT_mmacosx_version_min_EQ);
      OSXVersion = Args.MakeJoinedArg(nullptr, O, OSXTarget);
      Args.append(OSXVersion);
    } else if (!iOSTarget.empty()) {
      const Option O = Opts.getOption(options::OPT_miphoneos_version_min_EQ);
      iOSVersion = Args.MakeJoinedArg(nullptr, O, iOSTarget);
      Args.append(iOSVersion);
    } else if (!TvOSTarget.empty()) {
      const Option O = Opts.getOption(options::OPT_mtvos_version_min_EQ);
      TvOSVersion = Args.MakeJoinedArg(nullptr, O, TvOSTarget);
      Args.append(TvOSVersion);
    } else if (!WatchOSTarget.empty()) {
      const Option O = Opts.getOption(options::OPT_mwatchos_version_min_EQ);
      WatchOSVersion = Args.MakeJoinedArg(nullptr, O, WatchOSTarget);
      Args.append(WatchOSVersion);
    }
  }

  DarwinPlatformKind Platform;
  if (OSXVersion)
    Platform = MacOS;
  else if (iOSVersion)
    Platform = IPhoneOS;
  else if (TvOSVersion)
    Platform = TvOS;
  else if (WatchOSVersion)
    Platform = WatchOS;
  else
    llvm_unreachable("Unable to infer Darwin variant");

  // Set the tool chain target information.
  unsigned Major, Minor, Micro;
  bool HadExtra;
  if (Platform == MacOS) {
    assert((!iOSVersion && !TvOSVersion && !WatchOSVersion) &&
           "Unknown target platform!");
    if (!Driver::GetReleaseVersion(OSXVersion->getValue(), Major, Minor, Micro,
                                   HadExtra) ||
        HadExtra || Major != 10 || Minor >= 100 || Micro >= 100)
      getDriver().Diag(diag::err_drv_invalid_version_number)
          << OSXVersion->getAsString(Args);
  } else if (Platform == IPhoneOS) {
    assert(iOSVersion && "Unknown target platform!");
    if (!Driver::GetReleaseVersion(iOSVersion->getValue(), Major, Minor, Micro,
                                   HadExtra) ||
        HadExtra || Major >= 100 || Minor >= 100 || Micro >= 100)
      getDriver().Diag(diag::err_drv_invalid_version_number)
          << iOSVersion->getAsString(Args);
  } else if (Platform == TvOS) {
    if (!Driver::GetReleaseVersion(TvOSVersion->getValue(), Major, Minor,
                                   Micro, HadExtra) || HadExtra ||
        Major >= 100 || Minor >= 100 || Micro >= 100)
      getDriver().Diag(diag::err_drv_invalid_version_number)
          << TvOSVersion->getAsString(Args);
  } else if (Platform == WatchOS) {
    if (!Driver::GetReleaseVersion(WatchOSVersion->getValue(), Major, Minor,
                                   Micro, HadExtra) || HadExtra ||
        Major >= 10 || Minor >= 100 || Micro >= 100)
      getDriver().Diag(diag::err_drv_invalid_version_number)
          << WatchOSVersion->getAsString(Args);
  } else
    llvm_unreachable("unknown kind of Darwin platform");

  // Recognize iOS targets with an x86 architecture as the iOS simulator.
  if (iOSVersion && (getTriple().getArch() == llvm::Triple::x86 ||
                     getTriple().getArch() == llvm::Triple::x86_64))
    Platform = IPhoneOSSimulator;
  if (TvOSVersion && (getTriple().getArch() == llvm::Triple::x86 ||
                      getTriple().getArch() == llvm::Triple::x86_64))
    Platform = TvOSSimulator;
  if (WatchOSVersion && (getTriple().getArch() == llvm::Triple::x86 ||
                         getTriple().getArch() == llvm::Triple::x86_64))
    Platform = WatchOSSimulator;

  setTarget(Platform, Major, Minor, Micro);

  if (const Arg *A = Args.getLastArg(options::OPT_isysroot)) {
    StringRef SDK = getSDKName(A->getValue());
    if (SDK.size() > 0) {
      size_t StartVer = SDK.find_first_of("0123456789");
      StringRef SDKName = SDK.slice(0, StartVer);
      if (!SDKName.startswith(getPlatformFamily()))
        getDriver().Diag(diag::warn_incompatible_sysroot)
            << SDKName << getPlatformFamily();
    }
  }
}

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.
    if (const Arg *A = Args.getLastArg(options::OPT_isysroot)) {
      SmallString<128> P(A->getValue());
      llvm::sys::path::append(P, "usr", "lib", "libstdc++.dylib");

      if (!getVFS().exists(P)) {
        llvm::sys::path::remove_filename(P);
        llvm::sys::path::append(P, "libstdc++.6.dylib");
        if (getVFS().exists(P)) {
          CmdArgs.push_back(Args.MakeArgString(P));
          return;
        }
      }
    }

    // Otherwise, look in the root.
    // FIXME: This should be removed someday when we don't have to care about
    // 10.6 and earlier, where /usr/lib/libstdc++.dylib does not exist.
    if (!getVFS().exists("/usr/lib/libstdc++.dylib") &&
        getVFS().exists("/usr/lib/libstdc++.6.dylib")) {
      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).

  SmallString<128> P(getDriver().ResourceDir);
  llvm::sys::path::append(P, "lib", "darwin");

  // Use the newer cc_kext for iOS ARM after 6.0.
  if (isTargetWatchOS()) {
    llvm::sys::path::append(P, "libclang_rt.cc_kext_watchos.a");
  } else if (isTargetTvOS()) {
    llvm::sys::path::append(P, "libclang_rt.cc_kext_tvos.a");
  } else if (isTargetIPhoneOS()) {
    llvm::sys::path::append(P, "libclang_rt.cc_kext_ios.a");
  } else {
    llvm::sys::path::append(P, "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.
  if (getVFS().exists(P))
    CmdArgs.push_back(Args.MakeArgString(P));
}

DerivedArgList *MachO::TranslateArgs(const DerivedArgList &Args,
                                     StringRef BoundArch,
                                     Action::OffloadKind) 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 (Arg *A : Args) {
    if (A->getOption().matches(options::OPT_Xarch__)) {
      // Skip this argument unless the architecture matches either the toolchain
      // triple arch, or the arch being bound.
      llvm::Triple::ArchType XarchArch =
          tools::darwin::getArchTypeForMachOArchName(A->getValue(0));
      if (!(XarchArch == getArch() ||
            (!BoundArch.empty() &&
             XarchArch ==
                 tools::darwin::getArchTypeForMachOArchName(BoundArch))))
        continue;

      Arg *OriginalArg = A;
      unsigned Index = Args.getBaseArgs().MakeIndex(A->getValue(1));
      unsigned Prev = Index;
      std::unique_ptr<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().hasFlag(options::DriverOption)) {
        getDriver().Diag(diag::err_drv_invalid_Xarch_argument_isdriver)
            << A->getAsString(Args);
        continue;
      }

      XarchArg->setBaseArg(A);

      A = XarchArg.release();
      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().hasFlag(options::LinkerInput)) {
        // Convert the argument into individual Zlinker_input_args.
        for (const char *Value : A->getValues()) {
          DAL->AddSeparateArg(
              OriginalArg, Opts.getOption(options::OPT_Zlinker_input), Value);
        }
        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());
      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(nullptr, 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.empty()) {
    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(nullptr, MCpu, "601");
    else if (Name == "ppc603")
      DAL->AddJoinedArg(nullptr, MCpu, "603");
    else if (Name == "ppc604")
      DAL->AddJoinedArg(nullptr, MCpu, "604");
    else if (Name == "ppc604e")
      DAL->AddJoinedArg(nullptr, MCpu, "604e");
    else if (Name == "ppc750")
      DAL->AddJoinedArg(nullptr, MCpu, "750");
    else if (Name == "ppc7400")
      DAL->AddJoinedArg(nullptr, MCpu, "7400");
    else if (Name == "ppc7450")
      DAL->AddJoinedArg(nullptr, MCpu, "7450");
    else if (Name == "ppc970")
      DAL->AddJoinedArg(nullptr, MCpu, "970");

    else if (Name == "ppc64" || Name == "ppc64le")
      DAL->AddFlagArg(nullptr, Opts.getOption(options::OPT_m64));

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

    else if (Name == "x86_64")
      DAL->AddFlagArg(nullptr, Opts.getOption(options::OPT_m64));
    else if (Name == "x86_64h") {
      DAL->AddFlagArg(nullptr, Opts.getOption(options::OPT_m64));
      DAL->AddJoinedArg(nullptr, MArch, "x86_64h");
    }

    else if (Name == "arm")
      DAL->AddJoinedArg(nullptr, MArch, "armv4t");
    else if (Name == "armv4t")
      DAL->AddJoinedArg(nullptr, MArch, "armv4t");
    else if (Name == "armv5")
      DAL->AddJoinedArg(nullptr, MArch, "armv5tej");
    else if (Name == "xscale")
      DAL->AddJoinedArg(nullptr, MArch, "xscale");
    else if (Name == "armv6")
      DAL->AddJoinedArg(nullptr, MArch, "armv6k");
    else if (Name == "armv6m")
      DAL->AddJoinedArg(nullptr, MArch, "armv6m");
    else if (Name == "armv7")
      DAL->AddJoinedArg(nullptr, MArch, "armv7a");
    else if (Name == "armv7em")
      DAL->AddJoinedArg(nullptr, MArch, "armv7em");
    else if (Name == "armv7k")
      DAL->AddJoinedArg(nullptr, MArch, "armv7k");
    else if (Name == "armv7m")
      DAL->AddJoinedArg(nullptr, MArch, "armv7m");
    else if (Name == "armv7s")
      DAL->AddJoinedArg(nullptr, MArch, "armv7s");
  }

  return DAL;
}

void MachO::AddLinkRuntimeLibArgs(const ArgList &Args,
                                  ArgStringList &CmdArgs) const {
  // Embedded targets are simple at the moment, not supporting sanitizers and
  // with different libraries for each member of the product { static, PIC } x
  // { hard-float, soft-float }
  llvm::SmallString<32> CompilerRT = StringRef("libclang_rt.");
  CompilerRT +=
      (tools::arm::getARMFloatABI(*this, Args) == tools::arm::FloatABI::Hard)
          ? "hard"
          : "soft";
  CompilerRT += Args.hasArg(options::OPT_fPIC) ? "_pic.a" : "_static.a";

  AddLinkRuntimeLib(Args, CmdArgs, CompilerRT, false, true);
}

DerivedArgList *
Darwin::TranslateArgs(const DerivedArgList &Args, StringRef BoundArch,
                      Action::OffloadKind DeviceOffloadKind) const {
  // First get the generic Apple args, before moving onto Darwin-specific ones.
  DerivedArgList *DAL =
      MachO::TranslateArgs(Args, BoundArch, DeviceOffloadKind);
  const OptTable &Opts = getDriver().getOpts();

  // If no architecture is bound, none of the translations here are relevant.
  if (BoundArch.empty())
    return DAL;

  // 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);

  // For iOS 6, undo the translation to add -static for -mkernel/-fapple-kext.
  // FIXME: It would be far better to avoid inserting those -static arguments,
  // but we can't check the deployment target in the translation code until
  // it is set here.
  if (isTargetWatchOSBased() ||
      (isTargetIOSBased() && !isIPhoneOSVersionLT(6, 0))) {
    for (ArgList::iterator it = DAL->begin(), ie = DAL->end(); it != ie; ) {
      Arg *A = *it;
      ++it;
      if (A->getOption().getID() != options::OPT_mkernel &&
          A->getOption().getID() != options::OPT_fapple_kext)
        continue;
      assert(it != ie && "unexpected argument translation");
      A = *it;
      assert(A->getOption().getID() == options::OPT_static &&
             "missing expected -static argument");
      it = DAL->getArgs().erase(it);
    }
  }

  if (!Args.getLastArg(options::OPT_stdlib_EQ) &&
      GetCXXStdlibType(Args) == ToolChain::CST_Libcxx)
    DAL->AddJoinedArg(nullptr, Opts.getOption(options::OPT_stdlib_EQ),
                      "libc++");

  // Validate the C++ standard library choice.
  CXXStdlibType Type = GetCXXStdlibType(*DAL);
  if (Type == ToolChain::CST_Libcxx) {
    // Check whether the target provides libc++.
    StringRef where;

    // Complain about targeting iOS < 5.0 in any way.
    if (isTargetIOSBased() && isIPhoneOSVersionLT(5, 0))
      where = "iOS 5.0";

    if (where != StringRef()) {
      getDriver().Diag(clang::diag::err_drv_invalid_libcxx_deployment) << where;
    }
  }

  auto Arch = tools::darwin::getArchTypeForMachOArchName(BoundArch);
  if ((Arch == llvm::Triple::arm || Arch == llvm::Triple::thumb)) {
    if (Args.hasFlag(options::OPT_fomit_frame_pointer,
                     options::OPT_fno_omit_frame_pointer, false))
      getDriver().Diag(clang::diag::warn_drv_unsupported_opt_for_target)
          << "-fomit-frame-pointer" << BoundArch;
  }

  return DAL;
}

bool MachO::IsUnwindTablesDefault() const {
  return getArch() == llvm::Triple::x86_64;
}

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

bool Darwin::UseSjLjExceptions(const ArgList &Args) const {
  // Darwin uses SjLj exceptions on ARM.
  if (getTriple().getArch() != llvm::Triple::arm &&
      getTriple().getArch() != llvm::Triple::thumb)
    return false;

  // Only watchOS uses the new DWARF/Compact unwinding method.
  llvm::Triple Triple(ComputeLLVMTriple(Args));
  return !Triple.isWatchABI();
}

bool Darwin::SupportsEmbeddedBitcode() const {
  assert(TargetInitialized && "Target not initialized!");
  if (isTargetIPhoneOS() && isIPhoneOSVersionLT(6, 0))
    return false;
  return true;
}

bool MachO::isPICDefault() const { return true; }

bool MachO::isPIEDefault() const { return false; }

bool MachO::isPICDefaultForced() const {
  return (getArch() == llvm::Triple::x86_64 ||
          getArch() == llvm::Triple::aarch64);
}

bool MachO::SupportsProfiling() const {
  // Profiling instrumentation is only supported on x86.
  return getArch() == llvm::Triple::x86 || getArch() == llvm::Triple::x86_64;
}

void Darwin::addMinVersionArgs(const ArgList &Args,
                               ArgStringList &CmdArgs) const {
  VersionTuple TargetVersion = getTargetVersion();

  if (isTargetWatchOS())
    CmdArgs.push_back("-watchos_version_min");
  else if (isTargetWatchOSSimulator())
    CmdArgs.push_back("-watchos_simulator_version_min");
  else if (isTargetTvOS())
    CmdArgs.push_back("-tvos_version_min");
  else if (isTargetTvOSSimulator())
    CmdArgs.push_back("-tvos_simulator_version_min");
  else if (isTargetIOSSimulator())
    CmdArgs.push_back("-ios_simulator_version_min");
  else if (isTargetIOSBased())
    CmdArgs.push_back("-iphoneos_version_min");
  else {
    assert(isTargetMacOS() && "unexpected target");
    CmdArgs.push_back("-macosx_version_min");
  }

  CmdArgs.push_back(Args.MakeArgString(TargetVersion.getAsString()));
}

void Darwin::addStartObjectFileArgs(const ArgList &Args,
                                    ArgStringList &CmdArgs) const {
  // Derived from startfile spec.
  if (Args.hasArg(options::OPT_dynamiclib)) {
    // Derived from darwin_dylib1 spec.
    if (isTargetWatchOSBased()) {
      ; // watchOS does not need dylib1.o.
    } else if (isTargetIOSSimulator()) {
      ; // iOS simulator does not need dylib1.o.
    } else if (isTargetIPhoneOS()) {
      if (isIPhoneOSVersionLT(3, 1))
        CmdArgs.push_back("-ldylib1.o");
    } else {
      if (isMacosxVersionLT(10, 5))
        CmdArgs.push_back("-ldylib1.o");
      else if (isMacosxVersionLT(10, 6))
        CmdArgs.push_back("-ldylib1.10.5.o");
    }
  } else {
    if (Args.hasArg(options::OPT_bundle)) {
      if (!Args.hasArg(options::OPT_static)) {
        // Derived from darwin_bundle1 spec.
        if (isTargetWatchOSBased()) {
          ; // watchOS does not need bundle1.o.
        } else if (isTargetIOSSimulator()) {
          ; // iOS simulator does not need bundle1.o.
        } else if (isTargetIPhoneOS()) {
          if (isIPhoneOSVersionLT(3, 1))
            CmdArgs.push_back("-lbundle1.o");
        } else {
          if (isMacosxVersionLT(10, 6))
            CmdArgs.push_back("-lbundle1.o");
        }
      }
    } else {
      if (Args.hasArg(options::OPT_pg) && SupportsProfiling()) {
        if (Args.hasArg(options::OPT_static) ||
            Args.hasArg(options::OPT_object) ||
            Args.hasArg(options::OPT_preload)) {
          CmdArgs.push_back("-lgcrt0.o");
        } else {
          CmdArgs.push_back("-lgcrt1.o");

          // darwin_crt2 spec is empty.
        }
        // By default on OS X 10.8 and later, we don't link with a crt1.o
        // file and the linker knows to use _main as the entry point.  But,
        // when compiling with -pg, we need to link with the gcrt1.o file,
        // so pass the -no_new_main option to tell the linker to use the
        // "start" symbol as the entry point.
        if (isTargetMacOS() && !isMacosxVersionLT(10, 8))
          CmdArgs.push_back("-no_new_main");
      } else {
        if (Args.hasArg(options::OPT_static) ||
            Args.hasArg(options::OPT_object) ||
            Args.hasArg(options::OPT_preload)) {
          CmdArgs.push_back("-lcrt0.o");
        } else {
          // Derived from darwin_crt1 spec.
          if (isTargetWatchOSBased()) {
            ; // watchOS does not need crt1.o.
          } else if (isTargetIOSSimulator()) {
            ; // iOS simulator does not need crt1.o.
          } else if (isTargetIPhoneOS()) {
            if (getArch() == llvm::Triple::aarch64)
              ; // iOS does not need any crt1 files for arm64
            else if (isIPhoneOSVersionLT(3, 1))
              CmdArgs.push_back("-lcrt1.o");
            else if (isIPhoneOSVersionLT(6, 0))
              CmdArgs.push_back("-lcrt1.3.1.o");
          } else {
            if (isMacosxVersionLT(10, 5))
              CmdArgs.push_back("-lcrt1.o");
            else if (isMacosxVersionLT(10, 6))
              CmdArgs.push_back("-lcrt1.10.5.o");
            else if (isMacosxVersionLT(10, 8))
              CmdArgs.push_back("-lcrt1.10.6.o");

            // darwin_crt2 spec is empty.
          }
        }
      }
    }
  }

  if (!isTargetIPhoneOS() && Args.hasArg(options::OPT_shared_libgcc) &&
      !isTargetWatchOS() &&
      isMacosxVersionLT(10, 5)) {
    const char *Str = Args.MakeArgString(GetFilePath("crt3.o"));
    CmdArgs.push_back(Str);
  }
}

bool Darwin::SupportsObjCGC() const { return isTargetMacOS(); }

void Darwin::CheckObjCARC() const {
  if (isTargetIOSBased() || isTargetWatchOSBased() ||
      (isTargetMacOS() && !isMacosxVersionLT(10, 6)))
    return;
  getDriver().Diag(diag::err_arc_unsupported_on_toolchain);
}

SanitizerMask Darwin::getSupportedSanitizers() const {
  const bool IsX86_64 = getTriple().getArch() == llvm::Triple::x86_64;
  SanitizerMask Res = ToolChain::getSupportedSanitizers();
  Res |= SanitizerKind::Address;
  if (isTargetMacOS()) {
    if (!isMacosxVersionLT(10, 9))
      Res |= SanitizerKind::Vptr;
    Res |= SanitizerKind::SafeStack;
    if (IsX86_64)
      Res |= SanitizerKind::Thread;
  } else if (isTargetIOSSimulator() || isTargetTvOSSimulator()) {
    if (IsX86_64)
      Res |= SanitizerKind::Thread;
  }
  return Res;
}

void Darwin::printVerboseInfo(raw_ostream &OS) const {
  CudaInstallation.print(OS);
}

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

/// \brief Parse a GCCVersion object out of a string of text.
///
/// This is the primary means of forming GCCVersion objects.
/*static*/
Generic_GCC::GCCVersion Linux::GCCVersion::Parse(StringRef VersionText) {
  const GCCVersion BadVersion = {VersionText.str(), -1, -1, -1, "", "", ""};
  std::pair<StringRef, StringRef> First = VersionText.split('.');
  std::pair<StringRef, StringRef> Second = First.second.split('.');

  GCCVersion GoodVersion = {VersionText.str(), -1, -1, -1, "", "", ""};
  if (First.first.getAsInteger(10, GoodVersion.Major) || GoodVersion.Major < 0)
    return BadVersion;
  GoodVersion.MajorStr = First.first.str();
  if (First.second.empty())
    return GoodVersion;
  if (Second.first.getAsInteger(10, GoodVersion.Minor) || GoodVersion.Minor < 0)
    return BadVersion;
  GoodVersion.MinorStr = Second.first.str();

  // First look for a number prefix and parse that if present. Otherwise just
  // stash the entire patch string in the suffix, and leave the number
  // unspecified. This covers versions strings such as:
  //   5        (handled above)
  //   4.4
  //   4.4.0
  //   4.4.x
  //   4.4.2-rc4
  //   4.4.x-patched
  // And retains any patch number it finds.
  StringRef PatchText = GoodVersion.PatchSuffix = Second.second.str();
  if (!PatchText.empty()) {
    if (size_t EndNumber = PatchText.find_first_not_of("0123456789")) {
      // Try to parse the number and any suffix.
      if (PatchText.slice(0, EndNumber).getAsInteger(10, GoodVersion.Patch) ||
          GoodVersion.Patch < 0)
        return BadVersion;
      GoodVersion.PatchSuffix = PatchText.substr(EndNumber);
    }
  }

  return GoodVersion;
}

/// \brief Less-than for GCCVersion, implementing a Strict Weak Ordering.
bool Generic_GCC::GCCVersion::isOlderThan(int RHSMajor, int RHSMinor,
                                          int RHSPatch,
                                          StringRef RHSPatchSuffix) const {
  if (Major != RHSMajor)
    return Major < RHSMajor;
  if (Minor != RHSMinor)
    return Minor < RHSMinor;
  if (Patch != RHSPatch) {
    // Note that versions without a specified patch sort higher than those with
    // a patch.
    if (RHSPatch == -1)
      return true;
    if (Patch == -1)
      return false;

    // Otherwise just sort on the patch itself.
    return Patch < RHSPatch;
  }
  if (PatchSuffix != RHSPatchSuffix) {
    // Sort empty suffixes higher.
    if (RHSPatchSuffix.empty())
      return true;
    if (PatchSuffix.empty())
      return false;

    // Provide a lexicographic sort to make this a total ordering.
    return PatchSuffix < RHSPatchSuffix;
  }

  // The versions are equal.
  return false;
}

static llvm::StringRef getGCCToolchainDir(const ArgList &Args) {
  const Arg *A = Args.getLastArg(options::OPT_gcc_toolchain);
  if (A)
    return A->getValue();
  return GCC_INSTALL_PREFIX;
}

/// \brief Initialize a GCCInstallationDetector from the driver.
///
/// This performs all of the autodetection and sets up the various paths.
/// Once constructed, a GCCInstallationDetector is essentially immutable.
///
/// FIXME: We shouldn't need an explicit TargetTriple parameter here, and
/// should instead pull the target out of the driver. This is currently
/// necessary because the driver doesn't store the final version of the target
/// triple.
void Generic_GCC::GCCInstallationDetector::init(
    const llvm::Triple &TargetTriple, const ArgList &Args,
    ArrayRef<std::string> ExtraTripleAliases) {
  llvm::Triple BiarchVariantTriple = TargetTriple.isArch32Bit()
                                         ? TargetTriple.get64BitArchVariant()
                                         : TargetTriple.get32BitArchVariant();
  // The library directories which may contain GCC installations.
  SmallVector<StringRef, 4> CandidateLibDirs, CandidateBiarchLibDirs;
  // The compatible GCC triples for this particular architecture.
  SmallVector<StringRef, 16> CandidateTripleAliases;
  SmallVector<StringRef, 16> CandidateBiarchTripleAliases;
  CollectLibDirsAndTriples(TargetTriple, BiarchVariantTriple, CandidateLibDirs,
                           CandidateTripleAliases, CandidateBiarchLibDirs,
                           CandidateBiarchTripleAliases);

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

  StringRef GCCToolchainDir = getGCCToolchainDir(Args);
  if (GCCToolchainDir != "") {
    if (GCCToolchainDir.back() == '/')
      GCCToolchainDir = GCCToolchainDir.drop_back(); // remove the /

    Prefixes.push_back(GCCToolchainDir);
  } else {
    // If we have a SysRoot, try that first.
    if (!D.SysRoot.empty()) {
      Prefixes.push_back(D.SysRoot);
      Prefixes.push_back(D.SysRoot + "/usr");
    }

    // Then look for gcc installed alongside clang.
    Prefixes.push_back(D.InstalledDir + "/..");

    // Then look for distribution supplied gcc installations.
    if (D.SysRoot.empty()) {
      // Look for RHEL devtoolsets.
      Prefixes.push_back("/opt/rh/devtoolset-4/root/usr");
      Prefixes.push_back("/opt/rh/devtoolset-3/root/usr");
      Prefixes.push_back("/opt/rh/devtoolset-2/root/usr");
      Prefixes.push_back("/opt/rh/devtoolset-1.1/root/usr");
      Prefixes.push_back("/opt/rh/devtoolset-1.0/root/usr");
      // And finally in /usr.
      Prefixes.push_back("/usr");
    }
  }

  // Try to respect gcc-config on Gentoo. However, do that only
  // if --gcc-toolchain is not provided or equal to the Gentoo install
  // in /usr. This avoids accidentally enforcing the system GCC version
  // when using a custom toolchain.
  if (GCCToolchainDir == "" || GCCToolchainDir == D.SysRoot + "/usr") {
    for (StringRef CandidateTriple : ExtraTripleAliases) {
      if (ScanGentooGccConfig(TargetTriple, Args, CandidateTriple))
        return;
    }
    for (StringRef CandidateTriple : CandidateTripleAliases) {
      if (ScanGentooGccConfig(TargetTriple, Args, CandidateTriple))
        return;
    }
    for (StringRef CandidateTriple : CandidateBiarchTripleAliases) {
      if (ScanGentooGccConfig(TargetTriple, Args, CandidateTriple, true))
        return;
    }
  }

  // Loop over the various components which exist and select the best GCC
  // installation available. GCC installs are ranked by version number.
  Version = GCCVersion::Parse("0.0.0");
  for (const std::string &Prefix : Prefixes) {
    if (!D.getVFS().exists(Prefix))
      continue;
    for (StringRef Suffix : CandidateLibDirs) {
      const std::string LibDir = Prefix + Suffix.str();
      if (!D.getVFS().exists(LibDir))
        continue;
      for (StringRef Candidate : ExtraTripleAliases) // Try these first.
        ScanLibDirForGCCTriple(TargetTriple, Args, LibDir, Candidate);
      for (StringRef Candidate : CandidateTripleAliases)
        ScanLibDirForGCCTriple(TargetTriple, Args, LibDir, Candidate);
    }
    for (StringRef Suffix : CandidateBiarchLibDirs) {
      const std::string LibDir = Prefix + Suffix.str();
      if (!D.getVFS().exists(LibDir))
        continue;
      for (StringRef Candidate : CandidateBiarchTripleAliases)
        ScanLibDirForGCCTriple(TargetTriple, Args, LibDir, Candidate,
                               /*NeedsBiarchSuffix=*/ true);
    }
  }
}

void Generic_GCC::GCCInstallationDetector::print(raw_ostream &OS) const {
  for (const auto &InstallPath : CandidateGCCInstallPaths)
    OS << "Found candidate GCC installation: " << InstallPath << "\n";

  if (!GCCInstallPath.empty())
    OS << "Selected GCC installation: " << GCCInstallPath << "\n";

  for (const auto &Multilib : Multilibs)
    OS << "Candidate multilib: " << Multilib << "\n";

  if (Multilibs.size() != 0 || !SelectedMultilib.isDefault())
    OS << "Selected multilib: " << SelectedMultilib << "\n";
}

bool Generic_GCC::GCCInstallationDetector::getBiarchSibling(Multilib &M) const {
  if (BiarchSibling.hasValue()) {
    M = BiarchSibling.getValue();
    return true;
  }
  return false;
}

/*static*/ void Generic_GCC::GCCInstallationDetector::CollectLibDirsAndTriples(
    const llvm::Triple &TargetTriple, const llvm::Triple &BiarchTriple,
    SmallVectorImpl<StringRef> &LibDirs,
    SmallVectorImpl<StringRef> &TripleAliases,
    SmallVectorImpl<StringRef> &BiarchLibDirs,
    SmallVectorImpl<StringRef> &BiarchTripleAliases) {
  // Declare a bunch of static data sets that we'll select between below. These
  // are specifically designed to always refer to string literals to avoid any
  // lifetime or initialization issues.
  static const char *const AArch64LibDirs[] = {"/lib64", "/lib"};
  static const char *const AArch64Triples[] = {
      "aarch64-none-linux-gnu", "aarch64-linux-gnu", "aarch64-linux-android",
      "aarch64-redhat-linux", "aarch64-suse-linux"};
  static const char *const AArch64beLibDirs[] = {"/lib"};
  static const char *const AArch64beTriples[] = {"aarch64_be-none-linux-gnu",
                                                 "aarch64_be-linux-gnu"};

  static const char *const ARMLibDirs[] = {"/lib"};
  static const char *const ARMTriples[] = {"arm-linux-gnueabi",
                                           "arm-linux-androideabi"};
  static const char *const ARMHFTriples[] = {"arm-linux-gnueabihf",
                                             "armv7hl-redhat-linux-gnueabi"};
  static const char *const ARMebLibDirs[] = {"/lib"};
  static const char *const ARMebTriples[] = {"armeb-linux-gnueabi",
                                             "armeb-linux-androideabi"};
  static const char *const ARMebHFTriples[] = {
      "armeb-linux-gnueabihf", "armebv7hl-redhat-linux-gnueabi"};

  static const char *const X86_64LibDirs[] = {"/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", "x86_64-linux-android",
      "x86_64-unknown-linux"};
  static const char *const X32LibDirs[] = {"/libx32"};
  static const char *const X86LibDirs[] = {"/lib32", "/lib"};
  static const char *const X86Triples[] = {
      "i686-linux-gnu",       "i686-pc-linux-gnu",     "i486-linux-gnu",
      "i386-linux-gnu",       "i386-redhat-linux6E",   "i686-redhat-linux",
      "i586-redhat-linux",    "i386-redhat-linux",     "i586-suse-linux",
      "i486-slackware-linux", "i686-montavista-linux", "i686-linux-android",
      "i586-linux-gnu"};

  static const char *const MIPSLibDirs[] = {"/lib"};
  static const char *const MIPSTriples[] = {"mips-linux-gnu", "mips-mti-linux",
                                            "mips-mti-linux-gnu",
                                            "mips-img-linux-gnu"};
  static const char *const MIPSELLibDirs[] = {"/lib"};
  static const char *const MIPSELTriples[] = {"mipsel-linux-gnu",
                                              "mips-img-linux-gnu"};

  static const char *const MIPS64LibDirs[] = {"/lib64", "/lib"};
  static const char *const MIPS64Triples[] = {
      "mips64-linux-gnu", "mips-mti-linux-gnu", "mips-img-linux-gnu",
      "mips64-linux-gnuabi64"};
  static const char *const MIPS64ELLibDirs[] = {"/lib64", "/lib"};
  static const char *const MIPS64ELTriples[] = {
      "mips64el-linux-gnu", "mips-mti-linux-gnu", "mips-img-linux-gnu",
      "mips64el-linux-gnuabi64"};

  static const char *const MIPSELAndroidLibDirs[] = {"/lib", "/libr2",
                                                     "/libr6"};
  static const char *const MIPSELAndroidTriples[] = {"mipsel-linux-android"};
  static const char *const MIPS64ELAndroidLibDirs[] = {"/lib64", "/lib",
                                                       "/libr2", "/libr6"};
  static const char *const MIPS64ELAndroidTriples[] = {
      "mips64el-linux-android"};

  static const char *const PPCLibDirs[] = {"/lib32", "/lib"};
  static const char *const PPCTriples[] = {
      "powerpc-linux-gnu", "powerpc-unknown-linux-gnu", "powerpc-linux-gnuspe",
      "powerpc-suse-linux", "powerpc-montavista-linuxspe"};
  static const char *const PPC64LibDirs[] = {"/lib64", "/lib"};
  static const char *const PPC64Triples[] = {
      "powerpc64-linux-gnu", "powerpc64-unknown-linux-gnu",
      "powerpc64-suse-linux", "ppc64-redhat-linux"};
  static const char *const PPC64LELibDirs[] = {"/lib64", "/lib"};
  static const char *const PPC64LETriples[] = {
      "powerpc64le-linux-gnu", "powerpc64le-unknown-linux-gnu",
      "powerpc64le-suse-linux", "ppc64le-redhat-linux"};

  static const char *const SPARCv8LibDirs[] = {"/lib32", "/lib"};
  static const char *const SPARCv8Triples[] = {"sparc-linux-gnu",
                                               "sparcv8-linux-gnu"};
  static const char *const SPARCv9LibDirs[] = {"/lib64", "/lib"};
  static const char *const SPARCv9Triples[] = {"sparc64-linux-gnu",
                                               "sparcv9-linux-gnu"};

  static const char *const SystemZLibDirs[] = {"/lib64", "/lib"};
  static const char *const SystemZTriples[] = {
      "s390x-linux-gnu", "s390x-unknown-linux-gnu", "s390x-ibm-linux-gnu",
      "s390x-suse-linux", "s390x-redhat-linux"};

  // Solaris.
  static const char *const SolarisSPARCLibDirs[] = {"/gcc"};
  static const char *const SolarisSPARCTriples[] = {"sparc-sun-solaris2.11",
                                                    "i386-pc-solaris2.11"};

  using std::begin;
  using std::end;

  if (TargetTriple.getOS() == llvm::Triple::Solaris) {
    LibDirs.append(begin(SolarisSPARCLibDirs), end(SolarisSPARCLibDirs));
    TripleAliases.append(begin(SolarisSPARCTriples), end(SolarisSPARCTriples));
    return;
  }

  switch (TargetTriple.getArch()) {
  case llvm::Triple::aarch64:
    LibDirs.append(begin(AArch64LibDirs), end(AArch64LibDirs));
    TripleAliases.append(begin(AArch64Triples), end(AArch64Triples));
    BiarchLibDirs.append(begin(AArch64LibDirs), end(AArch64LibDirs));
    BiarchTripleAliases.append(begin(AArch64Triples), end(AArch64Triples));
    break;
  case llvm::Triple::aarch64_be:
    LibDirs.append(begin(AArch64beLibDirs), end(AArch64beLibDirs));
    TripleAliases.append(begin(AArch64beTriples), end(AArch64beTriples));
    BiarchLibDirs.append(begin(AArch64beLibDirs), end(AArch64beLibDirs));
    BiarchTripleAliases.append(begin(AArch64beTriples), end(AArch64beTriples));
    break;
  case llvm::Triple::arm:
  case llvm::Triple::thumb:
    LibDirs.append(begin(ARMLibDirs), end(ARMLibDirs));
    if (TargetTriple.getEnvironment() == llvm::Triple::GNUEABIHF) {
      TripleAliases.append(begin(ARMHFTriples), end(ARMHFTriples));
    } else {
      TripleAliases.append(begin(ARMTriples), end(ARMTriples));
    }
    break;
  case llvm::Triple::armeb:
  case llvm::Triple::thumbeb:
    LibDirs.append(begin(ARMebLibDirs), end(ARMebLibDirs));
    if (TargetTriple.getEnvironment() == llvm::Triple::GNUEABIHF) {
      TripleAliases.append(begin(ARMebHFTriples), end(ARMebHFTriples));
    } else {
      TripleAliases.append(begin(ARMebTriples), end(ARMebTriples));
    }
    break;
  case llvm::Triple::x86_64:
    LibDirs.append(begin(X86_64LibDirs), end(X86_64LibDirs));
    TripleAliases.append(begin(X86_64Triples), end(X86_64Triples));
    // x32 is always available when x86_64 is available, so adding it as
    // secondary arch with x86_64 triples
    if (TargetTriple.getEnvironment() == llvm::Triple::GNUX32) {
      BiarchLibDirs.append(begin(X32LibDirs), end(X32LibDirs));
      BiarchTripleAliases.append(begin(X86_64Triples), end(X86_64Triples));
    } else {
      BiarchLibDirs.append(begin(X86LibDirs), end(X86LibDirs));
      BiarchTripleAliases.append(begin(X86Triples), end(X86Triples));
    }
    break;
  case llvm::Triple::x86:
    LibDirs.append(begin(X86LibDirs), end(X86LibDirs));
    // MCU toolchain is 32 bit only and its triple alias is TargetTriple
    // itself, which will be appended below.
    if (!TargetTriple.isOSIAMCU()) {
      TripleAliases.append(begin(X86Triples), end(X86Triples));
      BiarchLibDirs.append(begin(X86_64LibDirs), end(X86_64LibDirs));
      BiarchTripleAliases.append(begin(X86_64Triples), end(X86_64Triples));
    }
    break;
  case llvm::Triple::mips:
    LibDirs.append(begin(MIPSLibDirs), end(MIPSLibDirs));
    TripleAliases.append(begin(MIPSTriples), end(MIPSTriples));
    BiarchLibDirs.append(begin(MIPS64LibDirs), end(MIPS64LibDirs));
    BiarchTripleAliases.append(begin(MIPS64Triples), end(MIPS64Triples));
    break;
  case llvm::Triple::mipsel:
    if (TargetTriple.isAndroid()) {
      LibDirs.append(begin(MIPSELAndroidLibDirs), end(MIPSELAndroidLibDirs));
      TripleAliases.append(begin(MIPSELAndroidTriples),
                           end(MIPSELAndroidTriples));
      BiarchLibDirs.append(begin(MIPS64ELAndroidLibDirs),
                           end(MIPS64ELAndroidLibDirs));
      BiarchTripleAliases.append(begin(MIPS64ELAndroidTriples),
                                 end(MIPS64ELAndroidTriples));

    } else {
      LibDirs.append(begin(MIPSELLibDirs), end(MIPSELLibDirs));
      TripleAliases.append(begin(MIPSELTriples), end(MIPSELTriples));
      TripleAliases.append(begin(MIPSTriples), end(MIPSTriples));
      BiarchLibDirs.append(begin(MIPS64ELLibDirs), end(MIPS64ELLibDirs));
      BiarchTripleAliases.append(begin(MIPS64ELTriples), end(MIPS64ELTriples));
    }
    break;
  case llvm::Triple::mips64:
    LibDirs.append(begin(MIPS64LibDirs), end(MIPS64LibDirs));
    TripleAliases.append(begin(MIPS64Triples), end(MIPS64Triples));
    BiarchLibDirs.append(begin(MIPSLibDirs), end(MIPSLibDirs));
    BiarchTripleAliases.append(begin(MIPSTriples), end(MIPSTriples));
    break;
  case llvm::Triple::mips64el:
    if (TargetTriple.isAndroid()) {
      LibDirs.append(begin(MIPS64ELAndroidLibDirs),
                     end(MIPS64ELAndroidLibDirs));
      TripleAliases.append(begin(MIPS64ELAndroidTriples),
                           end(MIPS64ELAndroidTriples));
      BiarchLibDirs.append(begin(MIPSELAndroidLibDirs),
                           end(MIPSELAndroidLibDirs));
      BiarchTripleAliases.append(begin(MIPSELAndroidTriples),
                                 end(MIPSELAndroidTriples));

    } else {
      LibDirs.append(begin(MIPS64ELLibDirs), end(MIPS64ELLibDirs));
      TripleAliases.append(begin(MIPS64ELTriples), end(MIPS64ELTriples));
      BiarchLibDirs.append(begin(MIPSELLibDirs), end(MIPSELLibDirs));
      BiarchTripleAliases.append(begin(MIPSELTriples), end(MIPSELTriples));
      BiarchTripleAliases.append(begin(MIPSTriples), end(MIPSTriples));
    }
    break;
  case llvm::Triple::ppc:
    LibDirs.append(begin(PPCLibDirs), end(PPCLibDirs));
    TripleAliases.append(begin(PPCTriples), end(PPCTriples));
    BiarchLibDirs.append(begin(PPC64LibDirs), end(PPC64LibDirs));
    BiarchTripleAliases.append(begin(PPC64Triples), end(PPC64Triples));
    break;
  case llvm::Triple::ppc64:
    LibDirs.append(begin(PPC64LibDirs), end(PPC64LibDirs));
    TripleAliases.append(begin(PPC64Triples), end(PPC64Triples));
    BiarchLibDirs.append(begin(PPCLibDirs), end(PPCLibDirs));
    BiarchTripleAliases.append(begin(PPCTriples), end(PPCTriples));
    break;
  case llvm::Triple::ppc64le:
    LibDirs.append(begin(PPC64LELibDirs), end(PPC64LELibDirs));
    TripleAliases.append(begin(PPC64LETriples), end(PPC64LETriples));
    break;
  case llvm::Triple::sparc:
  case llvm::Triple::sparcel:
    LibDirs.append(begin(SPARCv8LibDirs), end(SPARCv8LibDirs));
    TripleAliases.append(begin(SPARCv8Triples), end(SPARCv8Triples));
    BiarchLibDirs.append(begin(SPARCv9LibDirs), end(SPARCv9LibDirs));
    BiarchTripleAliases.append(begin(SPARCv9Triples), end(SPARCv9Triples));
    break;
  case llvm::Triple::sparcv9:
    LibDirs.append(begin(SPARCv9LibDirs), end(SPARCv9LibDirs));
    TripleAliases.append(begin(SPARCv9Triples), end(SPARCv9Triples));
    BiarchLibDirs.append(begin(SPARCv8LibDirs), end(SPARCv8LibDirs));
    BiarchTripleAliases.append(begin(SPARCv8Triples), end(SPARCv8Triples));
    break;
  case llvm::Triple::systemz:
    LibDirs.append(begin(SystemZLibDirs), end(SystemZLibDirs));
    TripleAliases.append(begin(SystemZTriples), end(SystemZTriples));
    break;
  default:
    // By default, just rely on the standard lib directories and the original
    // triple.
    break;
  }

  // Always append the drivers target triple to the end, in case it doesn't
  // match any of our aliases.
  TripleAliases.push_back(TargetTriple.str());

  // Also include the multiarch variant if it's different.
  if (TargetTriple.str() != BiarchTriple.str())
    BiarchTripleAliases.push_back(BiarchTriple.str());
}

// Parses the contents of version.txt in an CUDA installation.  It should
// contain one line of the from e.g. "CUDA Version 7.5.2".
static CudaVersion ParseCudaVersionFile(llvm::StringRef V) {
  if (!V.startswith("CUDA Version "))
    return CudaVersion::UNKNOWN;
  V = V.substr(strlen("CUDA Version "));
  int Major = -1, Minor = -1;
  auto First = V.split('.');
  auto Second = First.second.split('.');
  if (First.first.getAsInteger(10, Major) ||
      Second.first.getAsInteger(10, Minor))
    return CudaVersion::UNKNOWN;

  if (Major == 7 && Minor == 0) {
    // This doesn't appear to ever happen -- version.txt doesn't exist in the
    // CUDA 7 installs I've seen.  But no harm in checking.
    return CudaVersion::CUDA_70;
  }
  if (Major == 7 && Minor == 5)
    return CudaVersion::CUDA_75;
  if (Major == 8 && Minor == 0)
    return CudaVersion::CUDA_80;
  return CudaVersion::UNKNOWN;
}

CudaInstallationDetector::CudaInstallationDetector(
    const Driver &D, const llvm::Triple &HostTriple,
    const llvm::opt::ArgList &Args)
    : D(D) {
  SmallVector<std::string, 4> CudaPathCandidates;

  // In decreasing order so we prefer newer versions to older versions.
  std::initializer_list<const char *> Versions = {"8.0", "7.5", "7.0"};

  if (Args.hasArg(options::OPT_cuda_path_EQ)) {
    CudaPathCandidates.push_back(
        Args.getLastArgValue(options::OPT_cuda_path_EQ));
  } else if (HostTriple.isOSWindows()) {
    for (const char *Ver : Versions)
      CudaPathCandidates.push_back(
          D.SysRoot + "/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v" +
          Ver);
  } else {
    CudaPathCandidates.push_back(D.SysRoot + "/usr/local/cuda");
    for (const char *Ver : Versions)
      CudaPathCandidates.push_back(D.SysRoot + "/usr/local/cuda-" + Ver);
  }

  for (const auto &CudaPath : CudaPathCandidates) {
    if (CudaPath.empty() || !D.getVFS().exists(CudaPath))
      continue;

    InstallPath = CudaPath;
    BinPath = CudaPath + "/bin";
    IncludePath = InstallPath + "/include";
    LibDevicePath = InstallPath + "/nvvm/libdevice";

    auto &FS = D.getVFS();
    if (!(FS.exists(IncludePath) && FS.exists(BinPath) &&
          FS.exists(LibDevicePath)))
      continue;

    // On Linux, we have both lib and lib64 directories, and we need to choose
    // based on our triple.  On MacOS, we have only a lib directory.
    //
    // It's sufficient for our purposes to be flexible: If both lib and lib64
    // exist, we choose whichever one matches our triple.  Otherwise, if only
    // lib exists, we use it.
    if (HostTriple.isArch64Bit() && FS.exists(InstallPath + "/lib64"))
      LibPath = InstallPath + "/lib64";
    else if (FS.exists(InstallPath + "/lib"))
      LibPath = InstallPath + "/lib";
    else
      continue;

    llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> VersionFile =
        FS.getBufferForFile(InstallPath + "/version.txt");
    if (!VersionFile) {
      // CUDA 7.0 doesn't have a version.txt, so guess that's our version if
      // version.txt isn't present.
      Version = CudaVersion::CUDA_70;
    } else {
      Version = ParseCudaVersionFile((*VersionFile)->getBuffer());
    }

    std::error_code EC;
    for (llvm::sys::fs::directory_iterator LI(LibDevicePath, EC), LE;
         !EC && LI != LE; LI = LI.increment(EC)) {
      StringRef FilePath = LI->path();
      StringRef FileName = llvm::sys::path::filename(FilePath);
      // Process all bitcode filenames that look like libdevice.compute_XX.YY.bc
      const StringRef LibDeviceName = "libdevice.";
      if (!(FileName.startswith(LibDeviceName) && FileName.endswith(".bc")))
        continue;
      StringRef GpuArch = FileName.slice(
          LibDeviceName.size(), FileName.find('.', LibDeviceName.size()));
      LibDeviceMap[GpuArch] = FilePath.str();
      // Insert map entries for specifc devices with this compute
      // capability. NVCC's choice of the libdevice library version is
      // rather peculiar and depends on the CUDA version.
      if (GpuArch == "compute_20") {
        LibDeviceMap["sm_20"] = FilePath;
        LibDeviceMap["sm_21"] = FilePath;
        LibDeviceMap["sm_32"] = FilePath;
      } else if (GpuArch == "compute_30") {
        LibDeviceMap["sm_30"] = FilePath;
        if (Version < CudaVersion::CUDA_80) {
          LibDeviceMap["sm_50"] = FilePath;
          LibDeviceMap["sm_52"] = FilePath;
          LibDeviceMap["sm_53"] = FilePath;
        }
        LibDeviceMap["sm_60"] = FilePath;
        LibDeviceMap["sm_61"] = FilePath;
        LibDeviceMap["sm_62"] = FilePath;
      } else if (GpuArch == "compute_35") {
        LibDeviceMap["sm_35"] = FilePath;
        LibDeviceMap["sm_37"] = FilePath;
      } else if (GpuArch == "compute_50") {
        if (Version >= CudaVersion::CUDA_80) {
          LibDeviceMap["sm_50"] = FilePath;
          LibDeviceMap["sm_52"] = FilePath;
          LibDeviceMap["sm_53"] = FilePath;
        }
      }
    }

    IsValid = true;
    break;
  }
}

void CudaInstallationDetector::AddCudaIncludeArgs(
    const ArgList &DriverArgs, ArgStringList &CC1Args) const {
  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
    // Add cuda_wrappers/* to our system include path.  This lets us wrap
    // standard library headers.
    SmallString<128> P(D.ResourceDir);
    llvm::sys::path::append(P, "include");
    llvm::sys::path::append(P, "cuda_wrappers");
    CC1Args.push_back("-internal-isystem");
    CC1Args.push_back(DriverArgs.MakeArgString(P));
  }

  if (DriverArgs.hasArg(options::OPT_nocudainc))
    return;

  if (!isValid()) {
    D.Diag(diag::err_drv_no_cuda_installation);
    return;
  }

  CC1Args.push_back("-internal-isystem");
  CC1Args.push_back(DriverArgs.MakeArgString(getIncludePath()));
  CC1Args.push_back("-include");
  CC1Args.push_back("__clang_cuda_runtime_wrapper.h");
}

void CudaInstallationDetector::CheckCudaVersionSupportsArch(
    CudaArch Arch) const {
  if (Arch == CudaArch::UNKNOWN || Version == CudaVersion::UNKNOWN ||
      ArchsWithVersionTooLowErrors.count(Arch) > 0)
    return;

  auto RequiredVersion = MinVersionForCudaArch(Arch);
  if (Version < RequiredVersion) {
    ArchsWithVersionTooLowErrors.insert(Arch);
    D.Diag(diag::err_drv_cuda_version_too_low)
        << InstallPath << CudaArchToString(Arch) << CudaVersionToString(Version)
        << CudaVersionToString(RequiredVersion);
  }
}

void CudaInstallationDetector::print(raw_ostream &OS) const {
  if (isValid())
    OS << "Found CUDA installation: " << InstallPath << ", version "
       << CudaVersionToString(Version) << "\n";
}

namespace {
// Filter to remove Multilibs that don't exist as a suffix to Path
class FilterNonExistent {
  StringRef Base, File;
  vfs::FileSystem &VFS;

public:
  FilterNonExistent(StringRef Base, StringRef File, vfs::FileSystem &VFS)
      : Base(Base), File(File), VFS(VFS) {}
  bool operator()(const Multilib &M) {
    return !VFS.exists(Base + M.gccSuffix() + File);
  }
};
} // end anonymous namespace

static void addMultilibFlag(bool Enabled, const char *const Flag,
                            std::vector<std::string> &Flags) {
  if (Enabled)
    Flags.push_back(std::string("+") + Flag);
  else
    Flags.push_back(std::string("-") + Flag);
}

static bool isArmOrThumbArch(llvm::Triple::ArchType Arch) {
  return Arch == llvm::Triple::arm || Arch == llvm::Triple::thumb;
}

static bool isMipsArch(llvm::Triple::ArchType Arch) {
  return Arch == llvm::Triple::mips || Arch == llvm::Triple::mipsel ||
         Arch == llvm::Triple::mips64 || Arch == llvm::Triple::mips64el;
}

static bool isMips32(llvm::Triple::ArchType Arch) {
  return Arch == llvm::Triple::mips || Arch == llvm::Triple::mipsel;
}

static bool isMips64(llvm::Triple::ArchType Arch) {
  return Arch == llvm::Triple::mips64 || Arch == llvm::Triple::mips64el;
}

static bool isMipsEL(llvm::Triple::ArchType Arch) {
  return Arch == llvm::Triple::mipsel || Arch == llvm::Triple::mips64el;
}

static bool isMips16(const ArgList &Args) {
  Arg *A = Args.getLastArg(options::OPT_mips16, options::OPT_mno_mips16);
  return A && A->getOption().matches(options::OPT_mips16);
}

static bool isMicroMips(const ArgList &Args) {
  Arg *A = Args.getLastArg(options::OPT_mmicromips, options::OPT_mno_micromips);
  return A && A->getOption().matches(options::OPT_mmicromips);
}

namespace {
struct DetectedMultilibs {
  /// The set of multilibs that the detected installation supports.
  MultilibSet Multilibs;

  /// The primary multilib appropriate for the given flags.
  Multilib SelectedMultilib;

  /// On Biarch systems, this corresponds to the default multilib when
  /// targeting the non-default multilib. Otherwise, it is empty.
  llvm::Optional<Multilib> BiarchSibling;
};
} // end anonymous namespace

static Multilib makeMultilib(StringRef commonSuffix) {
  return Multilib(commonSuffix, commonSuffix, commonSuffix);
}

static bool findMipsCsMultilibs(const Multilib::flags_list &Flags,
                                FilterNonExistent &NonExistent,
                                DetectedMultilibs &Result) {
  // Check for Code Sourcery toolchain multilibs
  MultilibSet CSMipsMultilibs;
  {
    auto MArchMips16 = makeMultilib("/mips16").flag("+m32").flag("+mips16");

    auto MArchMicroMips =
        makeMultilib("/micromips").flag("+m32").flag("+mmicromips");

    auto MArchDefault = makeMultilib("").flag("-mips16").flag("-mmicromips");

    auto UCLibc = makeMultilib("/uclibc").flag("+muclibc");

    auto SoftFloat = makeMultilib("/soft-float").flag("+msoft-float");

    auto Nan2008 = makeMultilib("/nan2008").flag("+mnan=2008");

    auto DefaultFloat =
        makeMultilib("").flag("-msoft-float").flag("-mnan=2008");

    auto BigEndian = makeMultilib("").flag("+EB").flag("-EL");

    auto LittleEndian = makeMultilib("/el").flag("+EL").flag("-EB");

    // Note that this one's osSuffix is ""
    auto MAbi64 = makeMultilib("")
                      .gccSuffix("/64")
                      .includeSuffix("/64")
                      .flag("+mabi=n64")
                      .flag("-mabi=n32")
                      .flag("-m32");

    CSMipsMultilibs =
        MultilibSet()
            .Either(MArchMips16, MArchMicroMips, MArchDefault)
            .Maybe(UCLibc)
            .Either(SoftFloat, Nan2008, DefaultFloat)
            .FilterOut("/micromips/nan2008")
            .FilterOut("/mips16/nan2008")
            .Either(BigEndian, LittleEndian)
            .Maybe(MAbi64)
            .FilterOut("/mips16.*/64")
            .FilterOut("/micromips.*/64")
            .FilterOut(NonExistent)
            .setIncludeDirsCallback([](const Multilib &M) {
              std::vector<std::string> Dirs({"/include"});
              if (StringRef(M.includeSuffix()).startswith("/uclibc"))
                Dirs.push_back(
                    "/../../../../mips-linux-gnu/libc/uclibc/usr/include");
              else
                Dirs.push_back("/../../../../mips-linux-gnu/libc/usr/include");
              return Dirs;
            });
  }

  MultilibSet DebianMipsMultilibs;
  {
    Multilib MAbiN32 =
        Multilib().gccSuffix("/n32").includeSuffix("/n32").flag("+mabi=n32");

    Multilib M64 = Multilib()
                       .gccSuffix("/64")
                       .includeSuffix("/64")
                       .flag("+m64")
                       .flag("-m32")
                       .flag("-mabi=n32");

    Multilib M32 = Multilib().flag("-m64").flag("+m32").flag("-mabi=n32");

    DebianMipsMultilibs =
        MultilibSet().Either(M32, M64, MAbiN32).FilterOut(NonExistent);
  }

  // Sort candidates. Toolchain that best meets the directories tree goes first.
  // Then select the first toolchains matches command line flags.
  MultilibSet *Candidates[] = {&CSMipsMultilibs, &DebianMipsMultilibs};
  if (CSMipsMultilibs.size() < DebianMipsMultilibs.size())
    std::iter_swap(Candidates, Candidates + 1);
  for (const MultilibSet *Candidate : Candidates) {
    if (Candidate->select(Flags, Result.SelectedMultilib)) {
      if (Candidate == &DebianMipsMultilibs)
        Result.BiarchSibling = Multilib();
      Result.Multilibs = *Candidate;
      return true;
    }
  }
  return false;
}

static bool findMipsAndroidMultilibs(vfs::FileSystem &VFS, StringRef Path,
                                     const Multilib::flags_list &Flags,
                                     FilterNonExistent &NonExistent,
                                     DetectedMultilibs &Result) {

  MultilibSet AndroidMipsMultilibs =
      MultilibSet()
          .Maybe(Multilib("/mips-r2").flag("+march=mips32r2"))
          .Maybe(Multilib("/mips-r6").flag("+march=mips32r6"))
          .FilterOut(NonExistent);

  MultilibSet AndroidMipselMultilibs =
      MultilibSet()
          .Either(Multilib().flag("+march=mips32"),
                  Multilib("/mips-r2", "", "/mips-r2").flag("+march=mips32r2"),
                  Multilib("/mips-r6", "", "/mips-r6").flag("+march=mips32r6"))
          .FilterOut(NonExistent);

  MultilibSet AndroidMips64elMultilibs =
      MultilibSet()
          .Either(
              Multilib().flag("+march=mips64r6"),
              Multilib("/32/mips-r1", "", "/mips-r1").flag("+march=mips32"),
              Multilib("/32/mips-r2", "", "/mips-r2").flag("+march=mips32r2"),
              Multilib("/32/mips-r6", "", "/mips-r6").flag("+march=mips32r6"))
          .FilterOut(NonExistent);

  MultilibSet *MS = &AndroidMipsMultilibs;
  if (VFS.exists(Path + "/mips-r6"))
    MS = &AndroidMipselMultilibs;
  else if (VFS.exists(Path + "/32"))
    MS = &AndroidMips64elMultilibs;
  if (MS->select(Flags, Result.SelectedMultilib)) {
    Result.Multilibs = *MS;
    return true;
  }
  return false;
}

static bool findMipsMuslMultilibs(const Multilib::flags_list &Flags,
                                  FilterNonExistent &NonExistent,
                                  DetectedMultilibs &Result) {
  // Musl toolchain multilibs
  MultilibSet MuslMipsMultilibs;
  {
    auto MArchMipsR2 = makeMultilib("")
                           .osSuffix("/mips-r2-hard-musl")
                           .flag("+EB")
                           .flag("-EL")
                           .flag("+march=mips32r2");

    auto MArchMipselR2 = makeMultilib("/mipsel-r2-hard-musl")
                             .flag("-EB")
                             .flag("+EL")
                             .flag("+march=mips32r2");

    MuslMipsMultilibs = MultilibSet().Either(MArchMipsR2, MArchMipselR2);

    // Specify the callback that computes the include directories.
    MuslMipsMultilibs.setIncludeDirsCallback([](const Multilib &M) {
      return std::vector<std::string>(
          {"/../sysroot" + M.osSuffix() + "/usr/include"});
    });
  }
  if (MuslMipsMultilibs.select(Flags, Result.SelectedMultilib)) {
    Result.Multilibs = MuslMipsMultilibs;
    return true;
  }
  return false;
}

static bool findMipsMtiMultilibs(const Multilib::flags_list &Flags,
                                 FilterNonExistent &NonExistent,
                                 DetectedMultilibs &Result) {
  // CodeScape MTI toolchain v1.2 and early.
  MultilibSet MtiMipsMultilibsV1;
  {
    auto MArchMips32 = makeMultilib("/mips32")
                           .flag("+m32")
                           .flag("-m64")
                           .flag("-mmicromips")
                           .flag("+march=mips32");

    auto MArchMicroMips = makeMultilib("/micromips")
                              .flag("+m32")
                              .flag("-m64")
                              .flag("+mmicromips");

    auto MArchMips64r2 = makeMultilib("/mips64r2")
                             .flag("-m32")
                             .flag("+m64")
                             .flag("+march=mips64r2");

    auto MArchMips64 = makeMultilib("/mips64").flag("-m32").flag("+m64").flag(
        "-march=mips64r2");

    auto MArchDefault = makeMultilib("")
                            .flag("+m32")
                            .flag("-m64")
                            .flag("-mmicromips")
                            .flag("+march=mips32r2");

    auto Mips16 = makeMultilib("/mips16").flag("+mips16");

    auto UCLibc = makeMultilib("/uclibc").flag("+muclibc");

    auto MAbi64 =
        makeMultilib("/64").flag("+mabi=n64").flag("-mabi=n32").flag("-m32");

    auto BigEndian = makeMultilib("").flag("+EB").flag("-EL");

    auto LittleEndian = makeMultilib("/el").flag("+EL").flag("-EB");

    auto SoftFloat = makeMultilib("/sof").flag("+msoft-float");

    auto Nan2008 = makeMultilib("/nan2008").flag("+mnan=2008");

    MtiMipsMultilibsV1 =
        MultilibSet()
            .Either(MArchMips32, MArchMicroMips, MArchMips64r2, MArchMips64,
                    MArchDefault)
            .Maybe(UCLibc)
            .Maybe(Mips16)
            .FilterOut("/mips64/mips16")
            .FilterOut("/mips64r2/mips16")
            .FilterOut("/micromips/mips16")
            .Maybe(MAbi64)
            .FilterOut("/micromips/64")
            .FilterOut("/mips32/64")
            .FilterOut("^/64")
            .FilterOut("/mips16/64")
            .Either(BigEndian, LittleEndian)
            .Maybe(SoftFloat)
            .Maybe(Nan2008)
            .FilterOut(".*sof/nan2008")
            .FilterOut(NonExistent)
            .setIncludeDirsCallback([](const Multilib &M) {
              std::vector<std::string> Dirs({"/include"});
              if (StringRef(M.includeSuffix()).startswith("/uclibc"))
                Dirs.push_back("/../../../../sysroot/uclibc/usr/include");
              else
                Dirs.push_back("/../../../../sysroot/usr/include");
              return Dirs;
            });
  }

  // CodeScape IMG toolchain starting from v1.3.
  MultilibSet MtiMipsMultilibsV2;
  {
    auto BeHard = makeMultilib("/mips-r2-hard")
                      .flag("+EB")
                      .flag("-msoft-float")
                      .flag("-mnan=2008")
                      .flag("-muclibc");
    auto BeSoft = makeMultilib("/mips-r2-soft")
                      .flag("+EB")
                      .flag("+msoft-float")
                      .flag("-mnan=2008");
    auto ElHard = makeMultilib("/mipsel-r2-hard")
                      .flag("+EL")
                      .flag("-msoft-float")
                      .flag("-mnan=2008")
                      .flag("-muclibc");
    auto ElSoft = makeMultilib("/mipsel-r2-soft")
                      .flag("+EL")
                      .flag("+msoft-float")
                      .flag("-mnan=2008")
                      .flag("-mmicromips");
    auto BeHardNan = makeMultilib("/mips-r2-hard-nan2008")
                         .flag("+EB")
                         .flag("-msoft-float")
                         .flag("+mnan=2008")
                         .flag("-muclibc");
    auto ElHardNan = makeMultilib("/mipsel-r2-hard-nan2008")
                         .flag("+EL")
                         .flag("-msoft-float")
                         .flag("+mnan=2008")
                         .flag("-muclibc")
                         .flag("-mmicromips");
    auto BeHardNanUclibc = makeMultilib("/mips-r2-hard-nan2008-uclibc")
                               .flag("+EB")
                               .flag("-msoft-float")
                               .flag("+mnan=2008")
                               .flag("+muclibc");
    auto ElHardNanUclibc = makeMultilib("/mipsel-r2-hard-nan2008-uclibc")
                               .flag("+EL")
                               .flag("-msoft-float")
                               .flag("+mnan=2008")
                               .flag("+muclibc");
    auto BeHardUclibc = makeMultilib("/mips-r2-hard-uclibc")
                            .flag("+EB")
                            .flag("-msoft-float")
                            .flag("-mnan=2008")
                            .flag("+muclibc");
    auto ElHardUclibc = makeMultilib("/mipsel-r2-hard-uclibc")
                            .flag("+EL")
                            .flag("-msoft-float")
                            .flag("-mnan=2008")
                            .flag("+muclibc");
    auto ElMicroHardNan = makeMultilib("/micromipsel-r2-hard-nan2008")
                              .flag("+EL")
                              .flag("-msoft-float")
                              .flag("+mnan=2008")
                              .flag("+mmicromips");
    auto ElMicroSoft = makeMultilib("/micromipsel-r2-soft")
                           .flag("+EL")
                           .flag("+msoft-float")
                           .flag("-mnan=2008")
                           .flag("+mmicromips");

    auto O32 =
        makeMultilib("/lib").osSuffix("").flag("-mabi=n32").flag("-mabi=n64");
    auto N32 =
        makeMultilib("/lib32").osSuffix("").flag("+mabi=n32").flag("-mabi=n64");
    auto N64 =
        makeMultilib("/lib64").osSuffix("").flag("-mabi=n32").flag("+mabi=n64");

    MtiMipsMultilibsV2 =
        MultilibSet()
            .Either({BeHard, BeSoft, ElHard, ElSoft, BeHardNan, ElHardNan,
                     BeHardNanUclibc, ElHardNanUclibc, BeHardUclibc,
                     ElHardUclibc, ElMicroHardNan, ElMicroSoft})
            .Either(O32, N32, N64)
            .FilterOut(NonExistent)
            .setIncludeDirsCallback([](const Multilib &M) {
              return std::vector<std::string>({"/../../../../sysroot" +
                                               M.includeSuffix() +
                                               "/../usr/include"});
            })
            .setFilePathsCallback([](const Multilib &M) {
              return std::vector<std::string>(
                  {"/../../../../mips-mti-linux-gnu/lib" + M.gccSuffix()});
            });
  }
  for (auto Candidate : {&MtiMipsMultilibsV1, &MtiMipsMultilibsV2}) {
    if (Candidate->select(Flags, Result.SelectedMultilib)) {
      Result.Multilibs = *Candidate;
      return true;
    }
  }
  return false;
}

static bool findMipsImgMultilibs(const Multilib::flags_list &Flags,
                                 FilterNonExistent &NonExistent,
                                 DetectedMultilibs &Result) {
  // CodeScape IMG toolchain v1.2 and early.
  MultilibSet ImgMultilibsV1;
  {
    auto Mips64r6 = makeMultilib("/mips64r6").flag("+m64").flag("-m32");

    auto LittleEndian = makeMultilib("/el").flag("+EL").flag("-EB");

    auto MAbi64 =
        makeMultilib("/64").flag("+mabi=n64").flag("-mabi=n32").flag("-m32");

    ImgMultilibsV1 =
        MultilibSet()
            .Maybe(Mips64r6)
            .Maybe(MAbi64)
            .Maybe(LittleEndian)
            .FilterOut(NonExistent)
            .setIncludeDirsCallback([](const Multilib &M) {
              return std::vector<std::string>(
                  {"/include", "/../../../../sysroot/usr/include"});
            });
  }

  // CodeScape IMG toolchain starting from v1.3.
  MultilibSet ImgMultilibsV2;
  {
    auto BeHard = makeMultilib("/mips-r6-hard")
                      .flag("+EB")
                      .flag("-msoft-float")
                      .flag("-mmicromips");
    auto BeSoft = makeMultilib("/mips-r6-soft")
                      .flag("+EB")
                      .flag("+msoft-float")
                      .flag("-mmicromips");
    auto ElHard = makeMultilib("/mipsel-r6-hard")
                      .flag("+EL")
                      .flag("-msoft-float")
                      .flag("-mmicromips");
    auto ElSoft = makeMultilib("/mipsel-r6-soft")
                      .flag("+EL")
                      .flag("+msoft-float")
                      .flag("-mmicromips");
    auto BeMicroHard = makeMultilib("/micromips-r6-hard")
                           .flag("+EB")
                           .flag("-msoft-float")
                           .flag("+mmicromips");
    auto BeMicroSoft = makeMultilib("/micromips-r6-soft")
                           .flag("+EB")
                           .flag("+msoft-float")
                           .flag("+mmicromips");
    auto ElMicroHard = makeMultilib("/micromipsel-r6-hard")
                           .flag("+EL")
                           .flag("-msoft-float")
                           .flag("+mmicromips");
    auto ElMicroSoft = makeMultilib("/micromipsel-r6-soft")
                           .flag("+EL")
                           .flag("+msoft-float")
                           .flag("+mmicromips");

    auto O32 =
        makeMultilib("/lib").osSuffix("").flag("-mabi=n32").flag("-mabi=n64");
    auto N32 =
        makeMultilib("/lib32").osSuffix("").flag("+mabi=n32").flag("-mabi=n64");
    auto N64 =
        makeMultilib("/lib64").osSuffix("").flag("-mabi=n32").flag("+mabi=n64");

    ImgMultilibsV2 =
        MultilibSet()
            .Either({BeHard, BeSoft, ElHard, ElSoft, BeMicroHard, BeMicroSoft,
                     ElMicroHard, ElMicroSoft})
            .Either(O32, N32, N64)
            .FilterOut(NonExistent)
            .setIncludeDirsCallback([](const Multilib &M) {
              return std::vector<std::string>({"/../../../../sysroot" +
                                               M.includeSuffix() +
                                               "/../usr/include"});
            })
            .setFilePathsCallback([](const Multilib &M) {
              return std::vector<std::string>(
                  {"/../../../../mips-img-linux-gnu/lib" + M.gccSuffix()});
            });
  }
  for (auto Candidate : {&ImgMultilibsV1, &ImgMultilibsV2}) {
    if (Candidate->select(Flags, Result.SelectedMultilib)) {
      Result.Multilibs = *Candidate;
      return true;
    }
  }
  return false;
}

static bool findMIPSMultilibs(const Driver &D, const llvm::Triple &TargetTriple,
                              StringRef Path, const ArgList &Args,
                              DetectedMultilibs &Result) {
  FilterNonExistent NonExistent(Path, "/crtbegin.o", D.getVFS());

  StringRef CPUName;
  StringRef ABIName;
  tools::mips::getMipsCPUAndABI(Args, TargetTriple, CPUName, ABIName);

  llvm::Triple::ArchType TargetArch = TargetTriple.getArch();

  Multilib::flags_list Flags;
  addMultilibFlag(isMips32(TargetArch), "m32", Flags);
  addMultilibFlag(isMips64(TargetArch), "m64", Flags);
  addMultilibFlag(isMips16(Args), "mips16", Flags);
  addMultilibFlag(CPUName == "mips32", "march=mips32", Flags);
  addMultilibFlag(CPUName == "mips32r2" || CPUName == "mips32r3" ||
                      CPUName == "mips32r5" || CPUName == "p5600",
                  "march=mips32r2", Flags);
  addMultilibFlag(CPUName == "mips32r6", "march=mips32r6", Flags);
  addMultilibFlag(CPUName == "mips64", "march=mips64", Flags);
  addMultilibFlag(CPUName == "mips64r2" || CPUName == "mips64r3" ||
                      CPUName == "mips64r5" || CPUName == "octeon",
                  "march=mips64r2", Flags);
  addMultilibFlag(CPUName == "mips64r6", "march=mips64r6", Flags);
  addMultilibFlag(isMicroMips(Args), "mmicromips", Flags);
  addMultilibFlag(tools::mips::isUCLibc(Args), "muclibc", Flags);
  addMultilibFlag(tools::mips::isNaN2008(Args, TargetTriple), "mnan=2008",
                  Flags);
  addMultilibFlag(ABIName == "n32", "mabi=n32", Flags);
  addMultilibFlag(ABIName == "n64", "mabi=n64", Flags);
  addMultilibFlag(isSoftFloatABI(Args), "msoft-float", Flags);
  addMultilibFlag(!isSoftFloatABI(Args), "mhard-float", Flags);
  addMultilibFlag(isMipsEL(TargetArch), "EL", Flags);
  addMultilibFlag(!isMipsEL(TargetArch), "EB", Flags);

  if (TargetTriple.isAndroid())
    return findMipsAndroidMultilibs(D.getVFS(), Path, Flags, NonExistent,
                                    Result);

  if (TargetTriple.getVendor() == llvm::Triple::MipsTechnologies &&
      TargetTriple.getOS() == llvm::Triple::Linux &&
      TargetTriple.getEnvironment() == llvm::Triple::UnknownEnvironment)
    return findMipsMuslMultilibs(Flags, NonExistent, Result);

  if (TargetTriple.getVendor() == llvm::Triple::MipsTechnologies &&
      TargetTriple.getOS() == llvm::Triple::Linux &&
      TargetTriple.getEnvironment() == llvm::Triple::GNU)
    return findMipsMtiMultilibs(Flags, NonExistent, Result);

  if (TargetTriple.getVendor() == llvm::Triple::ImaginationTechnologies &&
      TargetTriple.getOS() == llvm::Triple::Linux &&
      TargetTriple.getEnvironment() == llvm::Triple::GNU)
    return findMipsImgMultilibs(Flags, NonExistent, Result);

  if (findMipsCsMultilibs(Flags, NonExistent, Result))
    return true;

  // Fallback to the regular toolchain-tree structure.
  Multilib Default;
  Result.Multilibs.push_back(Default);
  Result.Multilibs.FilterOut(NonExistent);

  if (Result.Multilibs.select(Flags, Result.SelectedMultilib)) {
    Result.BiarchSibling = Multilib();
    return true;
  }

  return false;
}

static void findAndroidArmMultilibs(const Driver &D,
                                    const llvm::Triple &TargetTriple,
                                    StringRef Path, const ArgList &Args,
                                    DetectedMultilibs &Result) {
  // Find multilibs with subdirectories like armv7-a, thumb, armv7-a/thumb.
  FilterNonExistent NonExistent(Path, "/crtbegin.o", D.getVFS());
  Multilib ArmV7Multilib = makeMultilib("/armv7-a")
                               .flag("+armv7")
                               .flag("-thumb");
  Multilib ThumbMultilib = makeMultilib("/thumb")
                               .flag("-armv7")
                               .flag("+thumb");
  Multilib ArmV7ThumbMultilib = makeMultilib("/armv7-a/thumb")
                               .flag("+armv7")
                               .flag("+thumb");
  Multilib DefaultMultilib = makeMultilib("")
                               .flag("-armv7")
                               .flag("-thumb");
  MultilibSet AndroidArmMultilibs =
      MultilibSet()
          .Either(ThumbMultilib, ArmV7Multilib,
                  ArmV7ThumbMultilib, DefaultMultilib)
          .FilterOut(NonExistent);

  Multilib::flags_list Flags;
  llvm::StringRef Arch = Args.getLastArgValue(options::OPT_march_EQ);
  bool IsArmArch = TargetTriple.getArch() == llvm::Triple::arm;
  bool IsThumbArch = TargetTriple.getArch() == llvm::Triple::thumb;
  bool IsV7SubArch = TargetTriple.getSubArch() == llvm::Triple::ARMSubArch_v7;
  bool IsThumbMode = IsThumbArch ||
      Args.hasFlag(options::OPT_mthumb, options::OPT_mno_thumb, false) ||
      (IsArmArch && llvm::ARM::parseArchISA(Arch) == llvm::ARM::IK_THUMB);
  bool IsArmV7Mode = (IsArmArch || IsThumbArch) &&
      (llvm::ARM::parseArchVersion(Arch) == 7 ||
       (IsArmArch && Arch == "" && IsV7SubArch));
  addMultilibFlag(IsArmV7Mode, "armv7", Flags);
  addMultilibFlag(IsThumbMode, "thumb", Flags);

  if (AndroidArmMultilibs.select(Flags, Result.SelectedMultilib))
    Result.Multilibs = AndroidArmMultilibs;
}

static bool findBiarchMultilibs(const Driver &D,
                                const llvm::Triple &TargetTriple,
                                StringRef Path, const ArgList &Args,
                                bool NeedsBiarchSuffix,
                                DetectedMultilibs &Result) {
  // Some versions of SUSE and Fedora on ppc64 put 32-bit libs
  // in what would normally be GCCInstallPath and put the 64-bit
  // libs in a subdirectory named 64. The simple logic we follow is that
  // *if* there is a subdirectory of the right name with crtbegin.o in it,
  // we use that. If not, and if not a biarch triple alias, we look for
  // crtbegin.o without the subdirectory.

  Multilib Default;
  Multilib Alt64 = Multilib()
                       .gccSuffix("/64")
                       .includeSuffix("/64")
                       .flag("-m32")
                       .flag("+m64")
                       .flag("-mx32");
  Multilib Alt32 = Multilib()
                       .gccSuffix("/32")
                       .includeSuffix("/32")
                       .flag("+m32")
                       .flag("-m64")
                       .flag("-mx32");
  Multilib Altx32 = Multilib()
                        .gccSuffix("/x32")
                        .includeSuffix("/x32")
                        .flag("-m32")
                        .flag("-m64")
                        .flag("+mx32");

  // GCC toolchain for IAMCU doesn't have crtbegin.o, so look for libgcc.a.
  FilterNonExistent NonExistent(
      Path, TargetTriple.isOSIAMCU() ? "/libgcc.a" : "/crtbegin.o", D.getVFS());

  // Determine default multilib from: 32, 64, x32
  // Also handle cases such as 64 on 32, 32 on 64, etc.
  enum { UNKNOWN, WANT32, WANT64, WANTX32 } Want = UNKNOWN;
  const bool IsX32 = TargetTriple.getEnvironment() == llvm::Triple::GNUX32;
  if (TargetTriple.isArch32Bit() && !NonExistent(Alt32))
    Want = WANT64;
  else if (TargetTriple.isArch64Bit() && IsX32 && !NonExistent(Altx32))
    Want = WANT64;
  else if (TargetTriple.isArch64Bit() && !IsX32 && !NonExistent(Alt64))
    Want = WANT32;
  else {
    if (TargetTriple.isArch32Bit())
      Want = NeedsBiarchSuffix ? WANT64 : WANT32;
    else if (IsX32)
      Want = NeedsBiarchSuffix ? WANT64 : WANTX32;
    else
      Want = NeedsBiarchSuffix ? WANT32 : WANT64;
  }

  if (Want == WANT32)
    Default.flag("+m32").flag("-m64").flag("-mx32");
  else if (Want == WANT64)
    Default.flag("-m32").flag("+m64").flag("-mx32");
  else if (Want == WANTX32)
    Default.flag("-m32").flag("-m64").flag("+mx32");
  else
    return false;

  Result.Multilibs.push_back(Default);
  Result.Multilibs.push_back(Alt64);
  Result.Multilibs.push_back(Alt32);
  Result.Multilibs.push_back(Altx32);

  Result.Multilibs.FilterOut(NonExistent);

  Multilib::flags_list Flags;
  addMultilibFlag(TargetTriple.isArch64Bit() && !IsX32, "m64", Flags);
  addMultilibFlag(TargetTriple.isArch32Bit(), "m32", Flags);
  addMultilibFlag(TargetTriple.isArch64Bit() && IsX32, "mx32", Flags);

  if (!Result.Multilibs.select(Flags, Result.SelectedMultilib))
    return false;

  if (Result.SelectedMultilib == Alt64 || Result.SelectedMultilib == Alt32 ||
      Result.SelectedMultilib == Altx32)
    Result.BiarchSibling = Default;

  return true;
}

void Generic_GCC::GCCInstallationDetector::scanLibDirForGCCTripleSolaris(
    const llvm::Triple &TargetArch, const llvm::opt::ArgList &Args,
    const std::string &LibDir, StringRef CandidateTriple,
    bool NeedsBiarchSuffix) {
  // Solaris is a special case. The GCC installation is under
  // /usr/gcc/<major>.<minor>/lib/gcc/<triple>/<major>.<minor>.<patch>/, so we
  // need to iterate twice.
  std::error_code EC;
  for (vfs::directory_iterator LI = D.getVFS().dir_begin(LibDir, EC), LE;
       !EC && LI != LE; LI = LI.increment(EC)) {
    StringRef VersionText = llvm::sys::path::filename(LI->getName());
    GCCVersion CandidateVersion = GCCVersion::Parse(VersionText);

    if (CandidateVersion.Major != -1) // Filter obviously bad entries.
      if (!CandidateGCCInstallPaths.insert(LI->getName()).second)
        continue; // Saw this path before; no need to look at it again.
    if (CandidateVersion.isOlderThan(4, 1, 1))
      continue;
    if (CandidateVersion <= Version)
      continue;

    GCCInstallPath =
        LibDir + "/" + VersionText.str() + "/lib/gcc/" + CandidateTriple.str();
    if (!D.getVFS().exists(GCCInstallPath))
      continue;

    // If we make it here there has to be at least one GCC version, let's just
    // use the latest one.
    std::error_code EEC;
    for (vfs::directory_iterator
             LLI = D.getVFS().dir_begin(GCCInstallPath, EEC),
             LLE;
         !EEC && LLI != LLE; LLI = LLI.increment(EEC)) {

      StringRef SubVersionText = llvm::sys::path::filename(LLI->getName());
      GCCVersion CandidateSubVersion = GCCVersion::Parse(SubVersionText);

      if (CandidateSubVersion > Version)
        Version = CandidateSubVersion;
    }

    GCCTriple.setTriple(CandidateTriple);

    GCCInstallPath += "/" + Version.Text;
    GCCParentLibPath = GCCInstallPath + "/../../../../";

    IsValid = true;
  }
}

bool Generic_GCC::GCCInstallationDetector::ScanGCCForMultilibs(
    const llvm::Triple &TargetTriple, const ArgList &Args,
    StringRef Path, bool NeedsBiarchSuffix) {
  llvm::Triple::ArchType TargetArch = TargetTriple.getArch();
  DetectedMultilibs Detected;

  // Android standalone toolchain could have multilibs for ARM and Thumb.
  // Debian mips multilibs behave more like the rest of the biarch ones,
  // so handle them there
  if (isArmOrThumbArch(TargetArch) && TargetTriple.isAndroid()) {
    // It should also work without multilibs in a simplified toolchain.
    findAndroidArmMultilibs(D, TargetTriple, Path, Args, Detected);
  } else if (isMipsArch(TargetArch)) {
    if (!findMIPSMultilibs(D, TargetTriple, Path, Args, Detected))
      return false;
  } else if (!findBiarchMultilibs(D, TargetTriple, Path, Args,
                                  NeedsBiarchSuffix, Detected)) {
    return false;
  }

  Multilibs = Detected.Multilibs;
  SelectedMultilib = Detected.SelectedMultilib;
  BiarchSibling = Detected.BiarchSibling;

  return true;
}

void Generic_GCC::GCCInstallationDetector::ScanLibDirForGCCTriple(
    const llvm::Triple &TargetTriple, const ArgList &Args,
    const std::string &LibDir, StringRef CandidateTriple,
    bool NeedsBiarchSuffix) {
  llvm::Triple::ArchType TargetArch = TargetTriple.getArch();
  // There are various different suffixes involving the triple we
  // check for. We also record what is necessary to walk from each back
  // up to the lib directory. Specifically, the number of "up" steps
  // in the second half of each row is 1 + the number of path separators
  // in the first half.
  const std::string LibAndInstallSuffixes[][2] = {
      {"/gcc/" + CandidateTriple.str(), "/../../.."},

      // Debian puts cross-compilers in gcc-cross
      {"/gcc-cross/" + CandidateTriple.str(), "/../../.."},

      {"/" + CandidateTriple.str() + "/gcc/" + CandidateTriple.str(),
       "/../../../.."},

      // The Freescale PPC SDK has the gcc libraries in
      // <sysroot>/usr/lib/<triple>/x.y.z so have a look there as well.
      {"/" + CandidateTriple.str(), "/../.."},

      // Ubuntu has a strange mis-matched pair of triples that this happens to
      // match.
      // FIXME: It may be worthwhile to generalize this and look for a second
      // triple.
      {"/i386-linux-gnu/gcc/" + CandidateTriple.str(), "/../../../.."}};

  if (TargetTriple.getOS() == llvm::Triple::Solaris) {
    scanLibDirForGCCTripleSolaris(TargetTriple, Args, LibDir, CandidateTriple,
                                  NeedsBiarchSuffix);
    return;
  }

  // Only look at the final, weird Ubuntu suffix for i386-linux-gnu.
  const unsigned NumLibSuffixes = (llvm::array_lengthof(LibAndInstallSuffixes) -
                                   (TargetArch != llvm::Triple::x86));
  for (unsigned i = 0; i < NumLibSuffixes; ++i) {
    StringRef LibSuffix = LibAndInstallSuffixes[i][0];
    std::error_code EC;
    for (vfs::directory_iterator
             LI = D.getVFS().dir_begin(LibDir + LibSuffix, EC),
             LE;
         !EC && LI != LE; LI = LI.increment(EC)) {
      StringRef VersionText = llvm::sys::path::filename(LI->getName());
      GCCVersion CandidateVersion = GCCVersion::Parse(VersionText);
      if (CandidateVersion.Major != -1) // Filter obviously bad entries.
        if (!CandidateGCCInstallPaths.insert(LI->getName()).second)
          continue; // Saw this path before; no need to look at it again.
      if (CandidateVersion.isOlderThan(4, 1, 1))
        continue;
      if (CandidateVersion <= Version)
        continue;

      if (!ScanGCCForMultilibs(TargetTriple, Args, LI->getName(),
                               NeedsBiarchSuffix))
        continue;

      Version = CandidateVersion;
      GCCTriple.setTriple(CandidateTriple);
      // FIXME: We hack together the directory name here instead of
      // using LI to ensure stable path separators across Windows and
      // Linux.
      GCCInstallPath =
          LibDir + LibAndInstallSuffixes[i][0] + "/" + VersionText.str();
      GCCParentLibPath = GCCInstallPath + LibAndInstallSuffixes[i][1];
      IsValid = true;
    }
  }
}

bool Generic_GCC::GCCInstallationDetector::ScanGentooGccConfig(
    const llvm::Triple &TargetTriple, const ArgList &Args,
    StringRef CandidateTriple, bool NeedsBiarchSuffix) {
  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> File =
      D.getVFS().getBufferForFile(D.SysRoot + "/etc/env.d/gcc/config-" +
                                  CandidateTriple.str());
  if (File) {
    SmallVector<StringRef, 2> Lines;
    File.get()->getBuffer().split(Lines, "\n");
    for (StringRef Line : Lines) {
      // CURRENT=triple-version
      if (Line.consume_front("CURRENT=")) {
        const std::pair<StringRef, StringRef> ActiveVersion =
          Line.rsplit('-');
        // Note: Strictly speaking, we should be reading
        // /etc/env.d/gcc/${CURRENT} now. However, the file doesn't
        // contain anything new or especially useful to us.
        const std::string GentooPath = D.SysRoot + "/usr/lib/gcc/" +
                                       ActiveVersion.first.str() + "/" +
                                       ActiveVersion.second.str();
        if (D.getVFS().exists(GentooPath + "/crtbegin.o")) {
          if (!ScanGCCForMultilibs(TargetTriple, Args, GentooPath,
                                   NeedsBiarchSuffix))
            return false;

          Version = GCCVersion::Parse(ActiveVersion.second);
          GCCInstallPath = GentooPath;
          GCCParentLibPath = GentooPath + "/../../..";
          GCCTriple.setTriple(ActiveVersion.first);
          IsValid = true;
          return true;
        }
      }
    }
  }

  return false;
}

Generic_GCC::Generic_GCC(const Driver &D, const llvm::Triple &Triple,
                         const ArgList &Args)
    : ToolChain(D, Triple, Args), GCCInstallation(D),
      CudaInstallation(D, Triple, Args) {
  getProgramPaths().push_back(getDriver().getInstalledDir());
  if (getDriver().getInstalledDir() != getDriver().Dir)
    getProgramPaths().push_back(getDriver().Dir);
}

Generic_GCC::~Generic_GCC() {}

Tool *Generic_GCC::getTool(Action::ActionClass AC) const {
  switch (AC) {
  case Action::PreprocessJobClass:
    if (!Preprocess)
      Preprocess.reset(new tools::gcc::Preprocessor(*this));
    return Preprocess.get();
  case Action::CompileJobClass:
    if (!Compile)
      Compile.reset(new tools::gcc::Compiler(*this));
    return Compile.get();
  default:
    return ToolChain::getTool(AC);
  }
}

Tool *Generic_GCC::buildAssembler() const {
  return new tools::gnutools::Assembler(*this);
}

Tool *Generic_GCC::buildLinker() const { return new tools::gcc::Linker(*this); }

void Generic_GCC::printVerboseInfo(raw_ostream &OS) const {
  // Print the information about how we detected the GCC installation.
  GCCInstallation.print(OS);
  CudaInstallation.print(OS);
}

bool Generic_GCC::IsUnwindTablesDefault() const {
  return getArch() == llvm::Triple::x86_64;
}

bool Generic_GCC::isPICDefault() const {
  switch (getArch()) {
  case llvm::Triple::x86_64:
    return getTriple().isOSWindows();
  case llvm::Triple::ppc64:
  case llvm::Triple::ppc64le:
    return !getTriple().isOSBinFormatMachO() && !getTriple().isMacOSX();
  default:
    return false;
  }
}

bool Generic_GCC::isPIEDefault() const { return false; }

bool Generic_GCC::isPICDefaultForced() const {
  return getArch() == llvm::Triple::x86_64 && getTriple().isOSWindows();
}

bool Generic_GCC::IsIntegratedAssemblerDefault() const {
  switch (getTriple().getArch()) {
  case llvm::Triple::x86:
  case llvm::Triple::x86_64:
  case llvm::Triple::aarch64:
  case llvm::Triple::aarch64_be:
  case llvm::Triple::arm:
  case llvm::Triple::armeb:
  case llvm::Triple::bpfel:
  case llvm::Triple::bpfeb:
  case llvm::Triple::thumb:
  case llvm::Triple::thumbeb:
  case llvm::Triple::ppc:
  case llvm::Triple::ppc64:
  case llvm::Triple::ppc64le:
  case llvm::Triple::systemz:
  case llvm::Triple::mips:
  case llvm::Triple::mipsel:
    return true;
  case llvm::Triple::mips64:
  case llvm::Triple::mips64el:
    // Enabled for Debian mips64/mips64el only. Other targets are unable to
    // distinguish N32 from N64.
    if (getTriple().getEnvironment() == llvm::Triple::GNUABI64)
      return true;
    return false;
  default:
    return false;
  }
}

void Generic_GCC::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                               ArgStringList &CC1Args) const {
  if (DriverArgs.hasArg(options::OPT_nostdlibinc) ||
      DriverArgs.hasArg(options::OPT_nostdincxx))
    return;

  switch (GetCXXStdlibType(DriverArgs)) {
  case ToolChain::CST_Libcxx: {
    std::string Path = findLibCxxIncludePath();
    if (!Path.empty())
      addSystemInclude(DriverArgs, CC1Args, Path);
    break;
  }

  case ToolChain::CST_Libstdcxx:
    addLibStdCxxIncludePaths(DriverArgs, CC1Args);
    break;
  }
}

std::string Generic_GCC::findLibCxxIncludePath() const {
  // FIXME: The Linux behavior would probaby be a better approach here.
  return getDriver().SysRoot + "/usr/include/c++/v1";
}

void
Generic_GCC::addLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                      llvm::opt::ArgStringList &CC1Args) const {
  // By default, we don't assume we know where libstdc++ might be installed.
  // FIXME: If we have a valid GCCInstallation, use it.
}

/// \brief Helper to add the variant paths of a libstdc++ installation.
bool Generic_GCC::addLibStdCXXIncludePaths(
    Twine Base, Twine Suffix, StringRef GCCTriple, StringRef GCCMultiarchTriple,
    StringRef TargetMultiarchTriple, Twine IncludeSuffix,
    const ArgList &DriverArgs, ArgStringList &CC1Args) const {
  if (!getVFS().exists(Base + Suffix))
    return false;

  addSystemInclude(DriverArgs, CC1Args, Base + Suffix);

  // The vanilla GCC layout of libstdc++ headers uses a triple subdirectory. If
  // that path exists or we have neither a GCC nor target multiarch triple, use
  // this vanilla search path.
  if ((GCCMultiarchTriple.empty() && TargetMultiarchTriple.empty()) ||
      getVFS().exists(Base + Suffix + "/" + GCCTriple + IncludeSuffix)) {
    addSystemInclude(DriverArgs, CC1Args,
                     Base + Suffix + "/" + GCCTriple + IncludeSuffix);
  } else {
    // Otherwise try to use multiarch naming schemes which have normalized the
    // triples and put the triple before the suffix.
    //
    // GCC surprisingly uses *both* the GCC triple with a multilib suffix and
    // the target triple, so we support that here.
    addSystemInclude(DriverArgs, CC1Args,
                     Base + "/" + GCCMultiarchTriple + Suffix + IncludeSuffix);
    addSystemInclude(DriverArgs, CC1Args,
                     Base + "/" + TargetMultiarchTriple + Suffix);
  }

  addSystemInclude(DriverArgs, CC1Args, Base + Suffix + "/backward");
  return true;
}

llvm::opt::DerivedArgList *
Generic_GCC::TranslateArgs(const llvm::opt::DerivedArgList &Args, StringRef,
                           Action::OffloadKind DeviceOffloadKind) const {

  // If this tool chain is used for an OpenMP offloading device we have to make
  // sure we always generate a shared library regardless of the commands the
  // user passed to the host. This is required because the runtime library
  // is required to load the device image dynamically at run time.
  if (DeviceOffloadKind == Action::OFK_OpenMP) {
    DerivedArgList *DAL = new DerivedArgList(Args.getBaseArgs());
    const OptTable &Opts = getDriver().getOpts();

    // Request the shared library. Given that these options are decided
    // implicitly, they do not refer to any base argument.
    DAL->AddFlagArg(/*BaseArg=*/nullptr, Opts.getOption(options::OPT_shared));
    DAL->AddFlagArg(/*BaseArg=*/nullptr, Opts.getOption(options::OPT_fPIC));

    // Filter all the arguments we don't care passing to the offloading
    // toolchain as they can mess up with the creation of a shared library.
    for (auto *A : Args) {
      switch ((options::ID)A->getOption().getID()) {
      default:
        DAL->append(A);
        break;
      case options::OPT_shared:
      case options::OPT_dynamic:
      case options::OPT_static:
      case options::OPT_fPIC:
      case options::OPT_fno_PIC:
      case options::OPT_fpic:
      case options::OPT_fno_pic:
      case options::OPT_fPIE:
      case options::OPT_fno_PIE:
      case options::OPT_fpie:
      case options::OPT_fno_pie:
        break;
      }
    }
    return DAL;
  }
  return nullptr;
}

void Generic_ELF::addClangTargetOptions(const ArgList &DriverArgs,
                                        ArgStringList &CC1Args) const {
  const Generic_GCC::GCCVersion &V = GCCInstallation.getVersion();
  bool UseInitArrayDefault =
      getTriple().getArch() == llvm::Triple::aarch64 ||
      getTriple().getArch() == llvm::Triple::aarch64_be ||
      (getTriple().getOS() == llvm::Triple::Linux &&
       (!V.isOlderThan(4, 7, 0) || getTriple().isAndroid())) ||
      getTriple().getOS() == llvm::Triple::NaCl ||
      (getTriple().getVendor() == llvm::Triple::MipsTechnologies &&
       !getTriple().hasEnvironment());

  if (DriverArgs.hasFlag(options::OPT_fuse_init_array,
                         options::OPT_fno_use_init_array, UseInitArrayDefault))
    CC1Args.push_back("-fuse-init-array");
}

/// Mips Toolchain
MipsLLVMToolChain::MipsLLVMToolChain(const Driver &D,
                                     const llvm::Triple &Triple,
                                     const ArgList &Args)
    : Linux(D, Triple, Args) {
  // Select the correct multilib according to the given arguments.
  DetectedMultilibs Result;
  findMIPSMultilibs(D, Triple, "", Args, Result);
  Multilibs = Result.Multilibs;
  SelectedMultilib = Result.SelectedMultilib;

  // Find out the library suffix based on the ABI.
  LibSuffix = tools::mips::getMipsABILibSuffix(Args, Triple);
  getFilePaths().clear();
  getFilePaths().push_back(computeSysRoot() + "/usr/lib" + LibSuffix);
}

void MipsLLVMToolChain::AddClangSystemIncludeArgs(
    const ArgList &DriverArgs, ArgStringList &CC1Args) const {
  if (DriverArgs.hasArg(options::OPT_nostdinc))
    return;

  const Driver &D = getDriver();

  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
    SmallString<128> P(D.ResourceDir);
    llvm::sys::path::append(P, "include");
    addSystemInclude(DriverArgs, CC1Args, P);
  }

  if (DriverArgs.hasArg(options::OPT_nostdlibinc))
    return;

  const auto &Callback = Multilibs.includeDirsCallback();
  if (Callback) {
    for (const auto &Path : Callback(SelectedMultilib))
      addExternCSystemIncludeIfExists(DriverArgs, CC1Args,
                                      D.getInstalledDir() + Path);
  }
}

Tool *MipsLLVMToolChain::buildLinker() const {
  return new tools::gnutools::Linker(*this);
}

std::string MipsLLVMToolChain::computeSysRoot() const {
  if (!getDriver().SysRoot.empty())
    return getDriver().SysRoot + SelectedMultilib.osSuffix();

  const std::string InstalledDir(getDriver().getInstalledDir());
  std::string SysRootPath =
      InstalledDir + "/../sysroot" + SelectedMultilib.osSuffix();
  if (llvm::sys::fs::exists(SysRootPath))
    return SysRootPath;

  return std::string();
}

ToolChain::CXXStdlibType
MipsLLVMToolChain::GetCXXStdlibType(const ArgList &Args) const {
  Arg *A = Args.getLastArg(options::OPT_stdlib_EQ);
  if (A) {
    StringRef Value = A->getValue();
    if (Value != "libc++")
      getDriver().Diag(diag::err_drv_invalid_stdlib_name)
          << A->getAsString(Args);
  }

  return ToolChain::CST_Libcxx;
}

std::string MipsLLVMToolChain::findLibCxxIncludePath() const {
  if (const auto &Callback = Multilibs.includeDirsCallback()) {
    for (std::string Path : Callback(SelectedMultilib)) {
      Path = getDriver().getInstalledDir() + Path + "/c++/v1";
      if (llvm::sys::fs::exists(Path)) {
        return Path;
      }
    }
  }
  return "";
}

void MipsLLVMToolChain::AddCXXStdlibLibArgs(const ArgList &Args,
                                            ArgStringList &CmdArgs) const {
  assert((GetCXXStdlibType(Args) == ToolChain::CST_Libcxx) &&
         "Only -lc++ (aka libxx) is suported in this toolchain.");

  CmdArgs.push_back("-lc++");
  CmdArgs.push_back("-lc++abi");
  CmdArgs.push_back("-lunwind");
}

std::string MipsLLVMToolChain::getCompilerRT(const ArgList &Args,
                                             StringRef Component,
                                             bool Shared) const {
  SmallString<128> Path(getDriver().ResourceDir);
  llvm::sys::path::append(Path, SelectedMultilib.osSuffix(), "lib" + LibSuffix,
                          getOS());
  llvm::sys::path::append(Path, Twine("libclang_rt." + Component + "-" +
                                      "mips" + (Shared ? ".so" : ".a")));
  return Path.str();
}

/// Hexagon Toolchain

std::string HexagonToolChain::getHexagonTargetDir(
      const std::string &InstalledDir,
      const SmallVectorImpl<std::string> &PrefixDirs) const {
  std::string InstallRelDir;
  const Driver &D = getDriver();

  // Locate the rest of the toolchain ...
  for (auto &I : PrefixDirs)
    if (D.getVFS().exists(I))
      return I;

  if (getVFS().exists(InstallRelDir = InstalledDir + "/../target"))
    return InstallRelDir;

  return InstalledDir;
}

Optional<unsigned> HexagonToolChain::getSmallDataThreshold(
      const ArgList &Args) {
  StringRef Gn = "";
  if (Arg *A = Args.getLastArg(options::OPT_G, options::OPT_G_EQ,
                               options::OPT_msmall_data_threshold_EQ)) {
    Gn = A->getValue();
  } else if (Args.getLastArg(options::OPT_shared, options::OPT_fpic,
                             options::OPT_fPIC)) {
    Gn = "0";
  }

  unsigned G;
  if (!Gn.getAsInteger(10, G))
    return G;

  return None;
}

void HexagonToolChain::getHexagonLibraryPaths(const ArgList &Args,
      ToolChain::path_list &LibPaths) const {
  const Driver &D = getDriver();

  //----------------------------------------------------------------------------
  // -L Args
  //----------------------------------------------------------------------------
  for (Arg *A : Args.filtered(options::OPT_L))
    for (const char *Value : A->getValues())
      LibPaths.push_back(Value);

  //----------------------------------------------------------------------------
  // Other standard paths
  //----------------------------------------------------------------------------
  std::vector<std::string> RootDirs;
  std::copy(D.PrefixDirs.begin(), D.PrefixDirs.end(),
            std::back_inserter(RootDirs));

  std::string TargetDir = getHexagonTargetDir(D.getInstalledDir(),
                                              D.PrefixDirs);
  if (std::find(RootDirs.begin(), RootDirs.end(), TargetDir) == RootDirs.end())
    RootDirs.push_back(TargetDir);

  bool HasPIC = Args.hasArg(options::OPT_fpic, options::OPT_fPIC);
  // Assume G0 with -shared.
  bool HasG0 = Args.hasArg(options::OPT_shared);
  if (auto G = getSmallDataThreshold(Args))
    HasG0 = G.getValue() == 0;

  const std::string CpuVer = GetTargetCPUVersion(Args).str();
  for (auto &Dir : RootDirs) {
    std::string LibDir = Dir + "/hexagon/lib";
    std::string LibDirCpu = LibDir + '/' + CpuVer;
    if (HasG0) {
      if (HasPIC)
        LibPaths.push_back(LibDirCpu + "/G0/pic");
      LibPaths.push_back(LibDirCpu + "/G0");
    }
    LibPaths.push_back(LibDirCpu);
    LibPaths.push_back(LibDir);
  }
}

HexagonToolChain::HexagonToolChain(const Driver &D, const llvm::Triple &Triple,
                                   const llvm::opt::ArgList &Args)
    : Linux(D, Triple, Args) {
  const std::string TargetDir = getHexagonTargetDir(D.getInstalledDir(),
                                                    D.PrefixDirs);

  // Note: Generic_GCC::Generic_GCC adds InstalledDir and getDriver().Dir to
  // program paths
  const std::string BinDir(TargetDir + "/bin");
  if (D.getVFS().exists(BinDir))
    getProgramPaths().push_back(BinDir);

  ToolChain::path_list &LibPaths = getFilePaths();

  // Remove paths added by Linux toolchain. Currently Hexagon_TC really targets
  // 'elf' OS type, so the Linux paths are not appropriate. When we actually
  // support 'linux' we'll need to fix this up
  LibPaths.clear();
  getHexagonLibraryPaths(Args, LibPaths);
}

HexagonToolChain::~HexagonToolChain() {}

Tool *HexagonToolChain::buildAssembler() const {
  return new tools::hexagon::Assembler(*this);
}

Tool *HexagonToolChain::buildLinker() const {
  return new tools::hexagon::Linker(*this);
}

void HexagonToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                                 ArgStringList &CC1Args) const {
  if (DriverArgs.hasArg(options::OPT_nostdinc) ||
      DriverArgs.hasArg(options::OPT_nostdlibinc))
    return;

  const Driver &D = getDriver();
  std::string TargetDir = getHexagonTargetDir(D.getInstalledDir(),
                                              D.PrefixDirs);
  addExternCSystemInclude(DriverArgs, CC1Args, TargetDir + "/hexagon/include");
}


void HexagonToolChain::addLibStdCxxIncludePaths(
    const llvm::opt::ArgList &DriverArgs,
    llvm::opt::ArgStringList &CC1Args) const {
  const Driver &D = getDriver();
  std::string TargetDir = getHexagonTargetDir(D.InstalledDir, D.PrefixDirs);
  addLibStdCXXIncludePaths(TargetDir, "/hexagon/include/c++", "", "", "", "",
                           DriverArgs, CC1Args);
}

ToolChain::CXXStdlibType
HexagonToolChain::GetCXXStdlibType(const ArgList &Args) const {
  Arg *A = Args.getLastArg(options::OPT_stdlib_EQ);
  if (!A)
    return ToolChain::CST_Libstdcxx;

  StringRef Value = A->getValue();
  if (Value != "libstdc++")
    getDriver().Diag(diag::err_drv_invalid_stdlib_name) << A->getAsString(Args);

  return ToolChain::CST_Libstdcxx;
}

//
// Returns the default CPU for Hexagon. This is the default compilation target
// if no Hexagon processor is selected at the command-line.
//
const StringRef HexagonToolChain::GetDefaultCPU() {
  return "hexagonv60";
}

const StringRef HexagonToolChain::GetTargetCPUVersion(const ArgList &Args) {
  Arg *CpuArg = nullptr;
  if (Arg *A = Args.getLastArg(options::OPT_mcpu_EQ, options::OPT_march_EQ))
    CpuArg = A;

  StringRef CPU = CpuArg ? CpuArg->getValue() : GetDefaultCPU();
  if (CPU.startswith("hexagon"))
    return CPU.substr(sizeof("hexagon") - 1);
  return CPU;
}
// End Hexagon

/// AMDGPU Toolchain
AMDGPUToolChain::AMDGPUToolChain(const Driver &D, const llvm::Triple &Triple,
                                 const ArgList &Args)
  : Generic_ELF(D, Triple, Args) { }

Tool *AMDGPUToolChain::buildLinker() const {
  return new tools::amdgpu::Linker(*this);
}
// End AMDGPU

/// NaCl Toolchain
NaClToolChain::NaClToolChain(const Driver &D, const llvm::Triple &Triple,
                             const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {

  // Remove paths added by Generic_GCC. NaCl Toolchain cannot use the
  // default paths, and must instead only use the paths provided
  // with this toolchain based on architecture.
  path_list &file_paths = getFilePaths();
  path_list &prog_paths = getProgramPaths();

  file_paths.clear();
  prog_paths.clear();

  // Path for library files (libc.a, ...)
  std::string FilePath(getDriver().Dir + "/../");

  // Path for tools (clang, ld, etc..)
  std::string ProgPath(getDriver().Dir + "/../");

  // Path for toolchain libraries (libgcc.a, ...)
  std::string ToolPath(getDriver().ResourceDir + "/lib/");

  switch (Triple.getArch()) {
  case llvm::Triple::x86:
    file_paths.push_back(FilePath + "x86_64-nacl/lib32");
    file_paths.push_back(FilePath + "i686-nacl/usr/lib");
    prog_paths.push_back(ProgPath + "x86_64-nacl/bin");
    file_paths.push_back(ToolPath + "i686-nacl");
    break;
  case llvm::Triple::x86_64:
    file_paths.push_back(FilePath + "x86_64-nacl/lib");
    file_paths.push_back(FilePath + "x86_64-nacl/usr/lib");
    prog_paths.push_back(ProgPath + "x86_64-nacl/bin");
    file_paths.push_back(ToolPath + "x86_64-nacl");
    break;
  case llvm::Triple::arm:
    file_paths.push_back(FilePath + "arm-nacl/lib");
    file_paths.push_back(FilePath + "arm-nacl/usr/lib");
    prog_paths.push_back(ProgPath + "arm-nacl/bin");
    file_paths.push_back(ToolPath + "arm-nacl");
    break;
  case llvm::Triple::mipsel:
    file_paths.push_back(FilePath + "mipsel-nacl/lib");
    file_paths.push_back(FilePath + "mipsel-nacl/usr/lib");
    prog_paths.push_back(ProgPath + "bin");
    file_paths.push_back(ToolPath + "mipsel-nacl");
    break;
  default:
    break;
  }

  NaClArmMacrosPath = GetFilePath("nacl-arm-macros.s");
}

void NaClToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                              ArgStringList &CC1Args) const {
  const Driver &D = getDriver();
  if (DriverArgs.hasArg(options::OPT_nostdinc))
    return;

  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
    SmallString<128> P(D.ResourceDir);
    llvm::sys::path::append(P, "include");
    addSystemInclude(DriverArgs, CC1Args, P.str());
  }

  if (DriverArgs.hasArg(options::OPT_nostdlibinc))
    return;

  SmallString<128> P(D.Dir + "/../");
  switch (getTriple().getArch()) {
  case llvm::Triple::x86:
    // x86 is special because multilib style uses x86_64-nacl/include for libc
    // headers but the SDK wants i686-nacl/usr/include. The other architectures
    // have the same substring.
    llvm::sys::path::append(P, "i686-nacl/usr/include");
    addSystemInclude(DriverArgs, CC1Args, P.str());
    llvm::sys::path::remove_filename(P);
    llvm::sys::path::remove_filename(P);
    llvm::sys::path::remove_filename(P);
    llvm::sys::path::append(P, "x86_64-nacl/include");
    addSystemInclude(DriverArgs, CC1Args, P.str());
    return;
  case llvm::Triple::arm:
    llvm::sys::path::append(P, "arm-nacl/usr/include");
    break;
  case llvm::Triple::x86_64:
    llvm::sys::path::append(P, "x86_64-nacl/usr/include");
    break;
  case llvm::Triple::mipsel:
    llvm::sys::path::append(P, "mipsel-nacl/usr/include");
    break;
  default:
    return;
  }

  addSystemInclude(DriverArgs, CC1Args, P.str());
  llvm::sys::path::remove_filename(P);
  llvm::sys::path::remove_filename(P);
  llvm::sys::path::append(P, "include");
  addSystemInclude(DriverArgs, CC1Args, P.str());
}

void NaClToolChain::AddCXXStdlibLibArgs(const ArgList &Args,
                                        ArgStringList &CmdArgs) const {
  // Check for -stdlib= flags. We only support libc++ but this consumes the arg
  // if the value is libc++, and emits an error for other values.
  GetCXXStdlibType(Args);
  CmdArgs.push_back("-lc++");
}

std::string NaClToolChain::findLibCxxIncludePath() const {
  const Driver &D = getDriver();

  SmallString<128> P(D.Dir + "/../");
  switch (getTriple().getArch()) {
  case llvm::Triple::arm:
    llvm::sys::path::append(P, "arm-nacl/include/c++/v1");
    return P.str();
  case llvm::Triple::x86:
    llvm::sys::path::append(P, "x86_64-nacl/include/c++/v1");
    return P.str();
  case llvm::Triple::x86_64:
    llvm::sys::path::append(P, "x86_64-nacl/include/c++/v1");
    return P.str();
  case llvm::Triple::mipsel:
    llvm::sys::path::append(P, "mipsel-nacl/include/c++/v1");
    return P.str();
  default:
    return "";
  }
}

ToolChain::CXXStdlibType
NaClToolChain::GetCXXStdlibType(const ArgList &Args) const {
  if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {
    StringRef Value = A->getValue();
    if (Value == "libc++")
      return ToolChain::CST_Libcxx;
    getDriver().Diag(diag::err_drv_invalid_stdlib_name) << A->getAsString(Args);
  }

  return ToolChain::CST_Libcxx;
}

std::string
NaClToolChain::ComputeEffectiveClangTriple(const ArgList &Args,
                                           types::ID InputType) const {
  llvm::Triple TheTriple(ComputeLLVMTriple(Args, InputType));
  if (TheTriple.getArch() == llvm::Triple::arm &&
      TheTriple.getEnvironment() == llvm::Triple::UnknownEnvironment)
    TheTriple.setEnvironment(llvm::Triple::GNUEABIHF);
  return TheTriple.getTriple();
}

Tool *NaClToolChain::buildLinker() const {
  return new tools::nacltools::Linker(*this);
}

Tool *NaClToolChain::buildAssembler() const {
  if (getTriple().getArch() == llvm::Triple::arm)
    return new tools::nacltools::AssemblerARM(*this);
  return new tools::gnutools::Assembler(*this);
}
// End NaCl

/// 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 Driver &D, const llvm::Triple &Triple,
                           const ArgList &Args)
    : ToolChain(D, Triple, Args) {
  // Path mangling to find libexec
  std::string Path(getDriver().Dir);

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

TCEToolChain::~TCEToolChain() {}

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

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

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

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

TCELEToolChain::TCELEToolChain(const Driver &D, const llvm::Triple& Triple,
                               const ArgList &Args)
  : TCEToolChain(D, Triple, Args) {
}

TCELEToolChain::~TCELEToolChain() {}

// CloudABI - CloudABI tool chain which can call ld(1) directly.

CloudABI::CloudABI(const Driver &D, const llvm::Triple &Triple,
                   const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {
  SmallString<128> P(getDriver().Dir);
  llvm::sys::path::append(P, "..", getTriple().str(), "lib");
  getFilePaths().push_back(P.str());
}

std::string CloudABI::findLibCxxIncludePath() const {
  SmallString<128> P(getDriver().Dir);
  llvm::sys::path::append(P, "..", getTriple().str(), "include/c++/v1");
  return P.str();
}

void CloudABI::AddCXXStdlibLibArgs(const ArgList &Args,
                                   ArgStringList &CmdArgs) const {
  CmdArgs.push_back("-lc++");
  CmdArgs.push_back("-lc++abi");
  CmdArgs.push_back("-lunwind");
}

Tool *CloudABI::buildLinker() const {
  return new tools::cloudabi::Linker(*this);
}

bool CloudABI::isPIEDefault() const {
  // Only enable PIE on architectures that support PC-relative
  // addressing. PC-relative addressing is required, as the process
  // startup code must be able to relocate itself.
  switch (getTriple().getArch()) {
  case llvm::Triple::aarch64:
  case llvm::Triple::x86_64:
    return true;
  default:
    return false;
  }
}

SanitizerMask CloudABI::getSupportedSanitizers() const {
  SanitizerMask Res = ToolChain::getSupportedSanitizers();
  Res |= SanitizerKind::SafeStack;
  return Res;
}

SanitizerMask CloudABI::getDefaultSanitizers() const {
  return SanitizerKind::SafeStack;
}

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

Haiku::Haiku(const Driver &D, const llvm::Triple& Triple, const ArgList &Args)
  : Generic_ELF(D, Triple, Args) {

}

std::string Haiku::findLibCxxIncludePath() const {
  return getDriver().SysRoot + "/system/develop/headers/c++/v1";
}

void Haiku::addLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                     llvm::opt::ArgStringList &CC1Args) const {
  addLibStdCXXIncludePaths(getDriver().SysRoot, "/system/develop/headers/c++",
                           getTriple().str(), "", "", "", DriverArgs, CC1Args);
}

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

OpenBSD::OpenBSD(const Driver &D, const llvm::Triple &Triple,
                 const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {
  getFilePaths().push_back(getDriver().Dir + "/../lib");
  getFilePaths().push_back("/usr/lib");
}

Tool *OpenBSD::buildAssembler() const {
  return new tools::openbsd::Assembler(*this);
}

Tool *OpenBSD::buildLinker() const { return new tools::openbsd::Linker(*this); }

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

Bitrig::Bitrig(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {
  getFilePaths().push_back(getDriver().Dir + "/../lib");
  getFilePaths().push_back("/usr/lib");
}

Tool *Bitrig::buildAssembler() const {
  return new tools::bitrig::Assembler(*this);
}

Tool *Bitrig::buildLinker() const { return new tools::bitrig::Linker(*this); }

ToolChain::CXXStdlibType Bitrig::GetDefaultCXXStdlibType() const {
  return ToolChain::CST_Libcxx;
}

void Bitrig::addLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                      llvm::opt::ArgStringList &CC1Args) const {
  std::string Triple = getTriple().str();
  if (StringRef(Triple).startswith("amd64"))
    Triple = "x86_64" + Triple.substr(5);
  addLibStdCXXIncludePaths(getDriver().SysRoot, "/usr/include/c++/stdc++",
                           Triple, "", "", "", DriverArgs, CC1Args);
}

void Bitrig::AddCXXStdlibLibArgs(const ArgList &Args,
                                 ArgStringList &CmdArgs) const {
  switch (GetCXXStdlibType(Args)) {
  case ToolChain::CST_Libcxx:
    CmdArgs.push_back("-lc++");
    CmdArgs.push_back("-lc++abi");
    CmdArgs.push_back("-lpthread");
    break;
  case ToolChain::CST_Libstdcxx:
    CmdArgs.push_back("-lstdc++");
    break;
  }
}

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

FreeBSD::FreeBSD(const Driver &D, const llvm::Triple &Triple,
                 const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {

  // When targeting 32-bit platforms, look for '/usr/lib32/crt1.o' and fall
  // back to '/usr/lib' if it doesn't exist.
  if ((Triple.getArch() == llvm::Triple::x86 ||
       Triple.getArch() == llvm::Triple::ppc) &&
      D.getVFS().exists(getDriver().SysRoot + "/usr/lib32/crt1.o"))
    getFilePaths().push_back(getDriver().SysRoot + "/usr/lib32");
  else
    getFilePaths().push_back(getDriver().SysRoot + "/usr/lib");
}

ToolChain::CXXStdlibType FreeBSD::GetDefaultCXXStdlibType() const {
  if (getTriple().getOSMajorVersion() >= 10)
    return ToolChain::CST_Libcxx;
  return ToolChain::CST_Libstdcxx;
}

void FreeBSD::addLibStdCxxIncludePaths(
    const llvm::opt::ArgList &DriverArgs,
    llvm::opt::ArgStringList &CC1Args) const {
  addLibStdCXXIncludePaths(getDriver().SysRoot, "/usr/include/c++/4.2", "", "",
                           "", "", DriverArgs, CC1Args);
}

void FreeBSD::AddCXXStdlibLibArgs(const ArgList &Args,
                                  ArgStringList &CmdArgs) const {
  CXXStdlibType Type = GetCXXStdlibType(Args);
  bool Profiling = Args.hasArg(options::OPT_pg);

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

  case ToolChain::CST_Libstdcxx:
    CmdArgs.push_back(Profiling ? "-lstdc++_p" : "-lstdc++");
    break;
  }
}

Tool *FreeBSD::buildAssembler() const {
  return new tools::freebsd::Assembler(*this);
}

Tool *FreeBSD::buildLinker() const { return new tools::freebsd::Linker(*this); }

bool FreeBSD::UseSjLjExceptions(const ArgList &Args) const {
  // FreeBSD uses SjLj exceptions on ARM oabi.
  switch (getTriple().getEnvironment()) {
  case llvm::Triple::GNUEABIHF:
  case llvm::Triple::GNUEABI:
  case llvm::Triple::EABI:
    return false;

  default:
    return (getTriple().getArch() == llvm::Triple::arm ||
            getTriple().getArch() == llvm::Triple::thumb);
  }
}

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

bool FreeBSD::isPIEDefault() const { return getSanitizerArgs().requiresPIE(); }

SanitizerMask FreeBSD::getSupportedSanitizers() const {
  const bool IsX86 = getTriple().getArch() == llvm::Triple::x86;
  const bool IsX86_64 = getTriple().getArch() == llvm::Triple::x86_64;
  const bool IsMIPS64 = getTriple().getArch() == llvm::Triple::mips64 ||
                        getTriple().getArch() == llvm::Triple::mips64el;
  SanitizerMask Res = ToolChain::getSupportedSanitizers();
  Res |= SanitizerKind::Address;
  Res |= SanitizerKind::Vptr;
  if (IsX86_64 || IsMIPS64) {
    Res |= SanitizerKind::Leak;
    Res |= SanitizerKind::Thread;
  }
  if (IsX86 || IsX86_64) {
    Res |= SanitizerKind::SafeStack;
  }
  return Res;
}

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

NetBSD::NetBSD(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {
  if (getDriver().UseStdLib) {
    // When targeting a 32-bit platform, try the special directory used on
    // 64-bit hosts, and only fall back to the main library directory if that
    // doesn't work.
    // FIXME: It'd be nicer to test if this directory exists, but I'm not sure
    // what all logic is needed to emulate the '=' prefix here.
    switch (Triple.getArch()) {
    case llvm::Triple::x86:
      getFilePaths().push_back("=/usr/lib/i386");
      break;
    case llvm::Triple::arm:
    case llvm::Triple::armeb:
    case llvm::Triple::thumb:
    case llvm::Triple::thumbeb:
      switch (Triple.getEnvironment()) {
      case llvm::Triple::EABI:
      case llvm::Triple::GNUEABI:
        getFilePaths().push_back("=/usr/lib/eabi");
        break;
      case llvm::Triple::EABIHF:
      case llvm::Triple::GNUEABIHF:
        getFilePaths().push_back("=/usr/lib/eabihf");
        break;
      default:
        getFilePaths().push_back("=/usr/lib/oabi");
        break;
      }
      break;
    case llvm::Triple::mips64:
    case llvm::Triple::mips64el:
      if (tools::mips::hasMipsAbiArg(Args, "o32"))
        getFilePaths().push_back("=/usr/lib/o32");
      else if (tools::mips::hasMipsAbiArg(Args, "64"))
        getFilePaths().push_back("=/usr/lib/64");
      break;
    case llvm::Triple::ppc:
      getFilePaths().push_back("=/usr/lib/powerpc");
      break;
    case llvm::Triple::sparc:
      getFilePaths().push_back("=/usr/lib/sparc");
      break;
    default:
      break;
    }

    getFilePaths().push_back("=/usr/lib");
  }
}

Tool *NetBSD::buildAssembler() const {
  return new tools::netbsd::Assembler(*this);
}

Tool *NetBSD::buildLinker() const { return new tools::netbsd::Linker(*this); }

ToolChain::CXXStdlibType NetBSD::GetDefaultCXXStdlibType() const {
  unsigned Major, Minor, Micro;
  getTriple().getOSVersion(Major, Minor, Micro);
  if (Major >= 7 || Major == 0) {
    switch (getArch()) {
    case llvm::Triple::aarch64:
    case llvm::Triple::aarch64_be:
    case llvm::Triple::arm:
    case llvm::Triple::armeb:
    case llvm::Triple::thumb:
    case llvm::Triple::thumbeb:
    case llvm::Triple::ppc:
    case llvm::Triple::ppc64:
    case llvm::Triple::ppc64le:
    case llvm::Triple::sparc:
    case llvm::Triple::sparcv9:
    case llvm::Triple::x86:
    case llvm::Triple::x86_64:
      return ToolChain::CST_Libcxx;
    default:
      break;
    }
  }
  return ToolChain::CST_Libstdcxx;
}

std::string NetBSD::findLibCxxIncludePath() const {
  return getDriver().SysRoot + "/usr/include/c++/";
}

void NetBSD::addLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                      llvm::opt::ArgStringList &CC1Args) const {
  addLibStdCXXIncludePaths(getDriver().SysRoot, "/usr/include/g++", "", "", "",
                           "", DriverArgs, CC1Args);
}

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

Minix::Minix(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {
  getFilePaths().push_back(getDriver().Dir + "/../lib");
  getFilePaths().push_back("/usr/lib");
}

Tool *Minix::buildAssembler() const {
  return new tools::minix::Assembler(*this);
}

Tool *Minix::buildLinker() const { return new tools::minix::Linker(*this); }

static void addPathIfExists(const Driver &D, const Twine &Path,
                            ToolChain::path_list &Paths) {
  if (D.getVFS().exists(Path))
    Paths.push_back(Path.str());
}

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

Solaris::Solaris(const Driver &D, const llvm::Triple &Triple,
                 const ArgList &Args)
    : Generic_GCC(D, Triple, Args) {

  GCCInstallation.init(Triple, Args);

  path_list &Paths = getFilePaths();
  if (GCCInstallation.isValid())
    addPathIfExists(D, GCCInstallation.getInstallPath(), Paths);

  addPathIfExists(D, getDriver().getInstalledDir(), Paths);
  if (getDriver().getInstalledDir() != getDriver().Dir)
    addPathIfExists(D, getDriver().Dir, Paths);

  addPathIfExists(D, getDriver().SysRoot + getDriver().Dir + "/../lib", Paths);

  std::string LibPath = "/usr/lib/";
  switch (Triple.getArch()) {
  case llvm::Triple::x86:
  case llvm::Triple::sparc:
    break;
  case llvm::Triple::x86_64:
    LibPath += "amd64/";
    break;
  case llvm::Triple::sparcv9:
    LibPath += "sparcv9/";
    break;
  default:
    llvm_unreachable("Unsupported architecture");
  }

  addPathIfExists(D, getDriver().SysRoot + LibPath, Paths);
}

Tool *Solaris::buildAssembler() const {
  return new tools::solaris::Assembler(*this);
}

Tool *Solaris::buildLinker() const { return new tools::solaris::Linker(*this); }

void Solaris::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                           ArgStringList &CC1Args) const {
  if (DriverArgs.hasArg(options::OPT_nostdlibinc) ||
      DriverArgs.hasArg(options::OPT_nostdincxx))
    return;

  // Include the support directory for things like xlocale and fudged system
  // headers.
  // FIXME: This is a weird mix of libc++ and libstdc++. We should also be
  // checking the value of -stdlib= here and adding the includes for libc++
  // rather than libstdc++ if it's requested.
  addSystemInclude(DriverArgs, CC1Args, "/usr/include/c++/v1/support/solaris");

  if (GCCInstallation.isValid()) {
    GCCVersion Version = GCCInstallation.getVersion();
    addSystemInclude(DriverArgs, CC1Args,
                     getDriver().SysRoot + "/usr/gcc/" +
                     Version.MajorStr + "." +
                     Version.MinorStr +
                     "/include/c++/" + Version.Text);
    addSystemInclude(DriverArgs, CC1Args,
                     getDriver().SysRoot + "/usr/gcc/" + Version.MajorStr +
                     "." + Version.MinorStr + "/include/c++/" +
                     Version.Text + "/" +
                     GCCInstallation.getTriple().str());
  }
}

/// \brief Get our best guess at the multiarch triple for a target.
///
/// Debian-based systems are starting to use a multiarch setup where they use
/// a target-triple directory in the library and header search paths.
/// Unfortunately, this triple does not align with the vanilla target triple,
/// so we provide a rough mapping here.
static std::string getMultiarchTriple(const Driver &D,
                                      const llvm::Triple &TargetTriple,
                                      StringRef SysRoot) {
  llvm::Triple::EnvironmentType TargetEnvironment =
      TargetTriple.getEnvironment();

  // For most architectures, just use whatever we have rather than trying to be
  // clever.
  switch (TargetTriple.getArch()) {
  default:
    break;

  // We use the existence of '/lib/<triple>' as a directory to detect some
  // common linux triples that don't quite match the Clang triple for both
  // 32-bit and 64-bit targets. Multiarch fixes its install triples to these
  // regardless of what the actual target triple is.
  case llvm::Triple::arm:
  case llvm::Triple::thumb:
    if (TargetEnvironment == llvm::Triple::GNUEABIHF) {
      if (D.getVFS().exists(SysRoot + "/lib/arm-linux-gnueabihf"))
        return "arm-linux-gnueabihf";
    } else {
      if (D.getVFS().exists(SysRoot + "/lib/arm-linux-gnueabi"))
        return "arm-linux-gnueabi";
    }
    break;
  case llvm::Triple::armeb:
  case llvm::Triple::thumbeb:
    if (TargetEnvironment == llvm::Triple::GNUEABIHF) {
      if (D.getVFS().exists(SysRoot + "/lib/armeb-linux-gnueabihf"))
        return "armeb-linux-gnueabihf";
    } else {
      if (D.getVFS().exists(SysRoot + "/lib/armeb-linux-gnueabi"))
        return "armeb-linux-gnueabi";
    }
    break;
  case llvm::Triple::x86:
    if (D.getVFS().exists(SysRoot + "/lib/i386-linux-gnu"))
      return "i386-linux-gnu";
    break;
  case llvm::Triple::x86_64:
    // We don't want this for x32, otherwise it will match x86_64 libs
    if (TargetEnvironment != llvm::Triple::GNUX32 &&
        D.getVFS().exists(SysRoot + "/lib/x86_64-linux-gnu"))
      return "x86_64-linux-gnu";
    break;
  case llvm::Triple::aarch64:
    if (D.getVFS().exists(SysRoot + "/lib/aarch64-linux-gnu"))
      return "aarch64-linux-gnu";
    break;
  case llvm::Triple::aarch64_be:
    if (D.getVFS().exists(SysRoot + "/lib/aarch64_be-linux-gnu"))
      return "aarch64_be-linux-gnu";
    break;
  case llvm::Triple::mips:
    if (D.getVFS().exists(SysRoot + "/lib/mips-linux-gnu"))
      return "mips-linux-gnu";
    break;
  case llvm::Triple::mipsel:
    if (D.getVFS().exists(SysRoot + "/lib/mipsel-linux-gnu"))
      return "mipsel-linux-gnu";
    break;
  case llvm::Triple::mips64:
    if (D.getVFS().exists(SysRoot + "/lib/mips64-linux-gnu"))
      return "mips64-linux-gnu";
    if (D.getVFS().exists(SysRoot + "/lib/mips64-linux-gnuabi64"))
      return "mips64-linux-gnuabi64";
    break;
  case llvm::Triple::mips64el:
    if (D.getVFS().exists(SysRoot + "/lib/mips64el-linux-gnu"))
      return "mips64el-linux-gnu";
    if (D.getVFS().exists(SysRoot + "/lib/mips64el-linux-gnuabi64"))
      return "mips64el-linux-gnuabi64";
    break;
  case llvm::Triple::ppc:
    if (D.getVFS().exists(SysRoot + "/lib/powerpc-linux-gnuspe"))
      return "powerpc-linux-gnuspe";
    if (D.getVFS().exists(SysRoot + "/lib/powerpc-linux-gnu"))
      return "powerpc-linux-gnu";
    break;
  case llvm::Triple::ppc64:
    if (D.getVFS().exists(SysRoot + "/lib/powerpc64-linux-gnu"))
      return "powerpc64-linux-gnu";
    break;
  case llvm::Triple::ppc64le:
    if (D.getVFS().exists(SysRoot + "/lib/powerpc64le-linux-gnu"))
      return "powerpc64le-linux-gnu";
    break;
  case llvm::Triple::sparc:
    if (D.getVFS().exists(SysRoot + "/lib/sparc-linux-gnu"))
      return "sparc-linux-gnu";
    break;
  case llvm::Triple::sparcv9:
    if (D.getVFS().exists(SysRoot + "/lib/sparc64-linux-gnu"))
      return "sparc64-linux-gnu";
    break;
  case llvm::Triple::systemz:
    if (D.getVFS().exists(SysRoot + "/lib/s390x-linux-gnu"))
      return "s390x-linux-gnu";
    break;
  }
  return TargetTriple.str();
}

static StringRef getOSLibDir(const llvm::Triple &Triple, const ArgList &Args) {
  if (isMipsArch(Triple.getArch())) {
    if (Triple.isAndroid()) {
      StringRef CPUName;
      StringRef ABIName;
      tools::mips::getMipsCPUAndABI(Args, Triple, CPUName, ABIName);
      if (CPUName == "mips32r6")
        return "libr6";
      if (CPUName == "mips32r2")
        return "libr2";
    }
    // lib32 directory has a special meaning on MIPS targets.
    // It contains N32 ABI binaries. Use this folder if produce
    // code for N32 ABI only.
    if (tools::mips::hasMipsAbiArg(Args, "n32"))
      return "lib32";
    return Triple.isArch32Bit() ? "lib" : "lib64";
  }

  // It happens that only x86 and PPC use the 'lib32' variant of oslibdir, and
  // using that variant while targeting other architectures causes problems
  // because the libraries are laid out in shared system roots that can't cope
  // with a 'lib32' library search path being considered. So we only enable
  // them when we know we may need it.
  //
  // FIXME: This is a bit of a hack. We should really unify this code for
  // reasoning about oslibdir spellings with the lib dir spellings in the
  // GCCInstallationDetector, but that is a more significant refactoring.
  if (Triple.getArch() == llvm::Triple::x86 ||
      Triple.getArch() == llvm::Triple::ppc)
    return "lib32";

  if (Triple.getArch() == llvm::Triple::x86_64 &&
      Triple.getEnvironment() == llvm::Triple::GNUX32)
    return "libx32";

  return Triple.isArch32Bit() ? "lib" : "lib64";
}

static void addMultilibsFilePaths(const Driver &D, const MultilibSet &Multilibs,
                                  const Multilib &Multilib,
                                  StringRef InstallPath,
                                  ToolChain::path_list &Paths) {
  if (const auto &PathsCallback = Multilibs.filePathsCallback())
    for (const auto &Path : PathsCallback(Multilib))
      addPathIfExists(D, InstallPath + Path, Paths);
}

Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {
  GCCInstallation.init(Triple, Args);
  Multilibs = GCCInstallation.getMultilibs();
  llvm::Triple::ArchType Arch = Triple.getArch();
  std::string SysRoot = computeSysRoot();

  // Cross-compiling binutils and GCC installations (vanilla and openSUSE at
  // least) put various tools in a triple-prefixed directory off of the parent
  // of the GCC installation. We use the GCC triple here to ensure that we end
  // up with tools that support the same amount of cross compiling as the
  // detected GCC installation. For example, if we find a GCC installation
  // targeting x86_64, but it is a bi-arch GCC installation, it can also be
  // used to target i386.
  // FIXME: This seems unlikely to be Linux-specific.
  ToolChain::path_list &PPaths = getProgramPaths();
  PPaths.push_back(Twine(GCCInstallation.getParentLibPath() + "/../" +
                         GCCInstallation.getTriple().str() + "/bin")
                       .str());

  Distro Distro(D.getVFS());

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

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

  const bool IsAndroid = Triple.isAndroid();
  const bool IsMips = isMipsArch(Arch);

  if (IsMips && !SysRoot.empty())
    ExtraOpts.push_back("--sysroot=" + SysRoot);

  // Do not use 'gnu' hash style for Mips targets because .gnu.hash
  // and the MIPS ABI require .dynsym to be sorted in different ways.
  // .gnu.hash needs symbols to be grouped by hash code whereas the MIPS
  // ABI requires a mapping between the GOT and the symbol table.
  // Android loader does not support .gnu.hash.
  if (!IsMips && !IsAndroid) {
    if (Distro.IsRedhat() || Distro.IsOpenSUSE() ||
        (Distro.IsUbuntu() && Distro >= Distro::UbuntuMaverick))
      ExtraOpts.push_back("--hash-style=gnu");

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

  if (Distro.IsRedhat() && Distro != Distro::RHEL5 && Distro != Distro::RHEL6)
    ExtraOpts.push_back("--no-add-needed");

#ifdef ENABLE_LINKER_BUILD_ID
  ExtraOpts.push_back("--build-id");
#endif

  if (Distro.IsOpenSUSE())
    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 std::string OSLibDir = getOSLibDir(Triple, Args);
  const std::string MultiarchTriple = getMultiarchTriple(D, Triple, SysRoot);

  // Add the multilib suffixed paths where they are available.
  if (GCCInstallation.isValid()) {
    const llvm::Triple &GCCTriple = GCCInstallation.getTriple();
    const std::string &LibPath = GCCInstallation.getParentLibPath();
    const Multilib &Multilib = GCCInstallation.getMultilib();
    const MultilibSet &Multilibs = GCCInstallation.getMultilibs();

    // Add toolchain / multilib specific file paths.
    addMultilibsFilePaths(D, Multilibs, Multilib,
                          GCCInstallation.getInstallPath(), Paths);

    // Sourcery CodeBench MIPS toolchain holds some libraries under
    // a biarch-like suffix of the GCC installation.
    addPathIfExists(D, GCCInstallation.getInstallPath() + Multilib.gccSuffix(),
                    Paths);

    // GCC cross compiling toolchains will install target libraries which ship
    // as part of the toolchain under <prefix>/<triple>/<libdir> rather than as
    // any part of the GCC installation in
    // <prefix>/<libdir>/gcc/<triple>/<version>. This decision is somewhat
    // debatable, but is the reality today. We need to search this tree even
    // when we have a sysroot somewhere else. It is the responsibility of
    // whomever is doing the cross build targeting a sysroot using a GCC
    // installation that is *not* within the system root to ensure two things:
    //
    //  1) Any DSOs that are linked in from this tree or from the install path
    //     above must be present on the system root and found via an
    //     appropriate rpath.
    //  2) There must not be libraries installed into
    //     <prefix>/<triple>/<libdir> unless they should be preferred over
    //     those within the system root.
    //
    // Note that this matches the GCC behavior. See the below comment for where
    // Clang diverges from GCC's behavior.
    addPathIfExists(D, LibPath + "/../" + GCCTriple.str() + "/lib/../" +
                           OSLibDir + Multilib.osSuffix(),
                    Paths);

    // If the GCC installation we found is inside of the sysroot, we want to
    // prefer libraries installed in the parent prefix of the GCC installation.
    // It is important to *not* use these paths when the GCC installation is
    // outside of the system root as that can pick up unintended libraries.
    // This usually happens when there is an external cross compiler on the
    // host system, and a more minimal sysroot available that is the target of
    // the cross. Note that GCC does include some of these directories in some
    // configurations but this seems somewhere between questionable and simply
    // a bug.
    if (StringRef(LibPath).startswith(SysRoot)) {
      addPathIfExists(D, LibPath + "/" + MultiarchTriple, Paths);
      addPathIfExists(D, LibPath + "/../" + OSLibDir, Paths);
    }
  }

  // Similar to the logic for GCC above, if we currently running Clang inside
  // of the requested system root, add its parent library paths to
  // those searched.
  // FIXME: It's not clear whether we should use the driver's installed
  // directory ('Dir' below) or the ResourceDir.
  if (StringRef(D.Dir).startswith(SysRoot)) {
    addPathIfExists(D, D.Dir + "/../lib/" + MultiarchTriple, Paths);
    addPathIfExists(D, D.Dir + "/../" + OSLibDir, Paths);
  }

  addPathIfExists(D, SysRoot + "/lib/" + MultiarchTriple, Paths);
  addPathIfExists(D, SysRoot + "/lib/../" + OSLibDir, Paths);
  addPathIfExists(D, SysRoot + "/usr/lib/" + MultiarchTriple, Paths);
  addPathIfExists(D, SysRoot + "/usr/lib/../" + OSLibDir, Paths);

  // Try walking via the GCC triple path in case of biarch or multiarch GCC
  // installations with strange symlinks.
  if (GCCInstallation.isValid()) {
    addPathIfExists(D,
                    SysRoot + "/usr/lib/" + GCCInstallation.getTriple().str() +
                        "/../../" + OSLibDir,
                    Paths);

    // Add the 'other' biarch variant path
    Multilib BiarchSibling;
    if (GCCInstallation.getBiarchSibling(BiarchSibling)) {
      addPathIfExists(D, GCCInstallation.getInstallPath() +
                             BiarchSibling.gccSuffix(),
                      Paths);
    }

    // See comments above on the multilib variant for details of why this is
    // included even from outside the sysroot.
    const std::string &LibPath = GCCInstallation.getParentLibPath();
    const llvm::Triple &GCCTriple = GCCInstallation.getTriple();
    const Multilib &Multilib = GCCInstallation.getMultilib();
    addPathIfExists(D, LibPath + "/../" + GCCTriple.str() + "/lib" +
                           Multilib.osSuffix(),
                    Paths);

    // See comments above on the multilib variant for details of why this is
    // only included from within the sysroot.
    if (StringRef(LibPath).startswith(SysRoot))
      addPathIfExists(D, LibPath, Paths);
  }

  // Similar to the logic for GCC above, if we are currently running Clang
  // inside of the requested system root, add its parent library path to those
  // searched.
  // FIXME: It's not clear whether we should use the driver's installed
  // directory ('Dir' below) or the ResourceDir.
  if (StringRef(D.Dir).startswith(SysRoot))
    addPathIfExists(D, D.Dir + "/../lib", Paths);

  addPathIfExists(D, SysRoot + "/lib", Paths);
  addPathIfExists(D, SysRoot + "/usr/lib", Paths);
}

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

Tool *Linux::buildLinker() const { return new tools::gnutools::Linker(*this); }

Tool *Linux::buildAssembler() const {
  return new tools::gnutools::Assembler(*this);
}

std::string Linux::computeSysRoot() const {
  if (!getDriver().SysRoot.empty())
    return getDriver().SysRoot;

  if (!GCCInstallation.isValid() || !isMipsArch(getTriple().getArch()))
    return std::string();

  // Standalone MIPS toolchains use different names for sysroot folder
  // and put it into different places. Here we try to check some known
  // variants.

  const StringRef InstallDir = GCCInstallation.getInstallPath();
  const StringRef TripleStr = GCCInstallation.getTriple().str();
  const Multilib &Multilib = GCCInstallation.getMultilib();

  std::string Path =
      (InstallDir + "/../../../../" + TripleStr + "/libc" + Multilib.osSuffix())
          .str();

  if (getVFS().exists(Path))
    return Path;

  Path = (InstallDir + "/../../../../sysroot" + Multilib.osSuffix()).str();

  if (getVFS().exists(Path))
    return Path;

  return std::string();
}

std::string Linux::getDynamicLinker(const ArgList &Args) const {
  const llvm::Triple::ArchType Arch = getArch();
  const llvm::Triple &Triple = getTriple();

  const Distro Distro(getDriver().getVFS());

  if (Triple.isAndroid())
    return Triple.isArch64Bit() ? "/system/bin/linker64" : "/system/bin/linker";

  if (Triple.isMusl()) {
    std::string ArchName;
    bool IsArm = false;

    switch (Arch) {
    case llvm::Triple::arm:
    case llvm::Triple::thumb:
      ArchName = "arm";
      IsArm = true;
      break;
    case llvm::Triple::armeb:
    case llvm::Triple::thumbeb:
      ArchName = "armeb";
      IsArm = true;
      break;
    default:
      ArchName = Triple.getArchName().str();
    }
    if (IsArm &&
        (Triple.getEnvironment() == llvm::Triple::MuslEABIHF ||
         tools::arm::getARMFloatABI(*this, Args) == tools::arm::FloatABI::Hard))
      ArchName += "hf";

    return "/lib/ld-musl-" + ArchName + ".so.1";
  }

  std::string LibDir;
  std::string Loader;

  switch (Arch) {
  default:
    llvm_unreachable("unsupported architecture");

  case llvm::Triple::aarch64:
    LibDir = "lib";
    Loader = "ld-linux-aarch64.so.1";
    break;
  case llvm::Triple::aarch64_be:
    LibDir = "lib";
    Loader = "ld-linux-aarch64_be.so.1";
    break;
  case llvm::Triple::arm:
  case llvm::Triple::thumb:
  case llvm::Triple::armeb:
  case llvm::Triple::thumbeb: {
    const bool HF =
        Triple.getEnvironment() == llvm::Triple::GNUEABIHF ||
        tools::arm::getARMFloatABI(*this, Args) == tools::arm::FloatABI::Hard;

    LibDir = "lib";
    Loader = HF ? "ld-linux-armhf.so.3" : "ld-linux.so.3";
    break;
  }
  case llvm::Triple::mips:
  case llvm::Triple::mipsel:
  case llvm::Triple::mips64:
  case llvm::Triple::mips64el: {
    bool LE = (Triple.getArch() == llvm::Triple::mipsel) ||
              (Triple.getArch() == llvm::Triple::mips64el);
    bool IsNaN2008 = tools::mips::isNaN2008(Args, Triple);

    LibDir = "lib" + tools::mips::getMipsABILibSuffix(Args, Triple);

    if (tools::mips::isUCLibc(Args))
      Loader = IsNaN2008 ? "ld-uClibc-mipsn8.so.0" : "ld-uClibc.so.0";
    else if (!Triple.hasEnvironment() &&
             Triple.getVendor() == llvm::Triple::VendorType::MipsTechnologies)
      Loader = LE ? "ld-musl-mipsel.so.1" : "ld-musl-mips.so.1";
    else
      Loader = IsNaN2008 ? "ld-linux-mipsn8.so.1" : "ld.so.1";

    break;
  }
  case llvm::Triple::ppc:
    LibDir = "lib";
    Loader = "ld.so.1";
    break;
  case llvm::Triple::ppc64:
    LibDir = "lib64";
    Loader =
        (tools::ppc::hasPPCAbiArg(Args, "elfv2")) ? "ld64.so.2" : "ld64.so.1";
    break;
  case llvm::Triple::ppc64le:
    LibDir = "lib64";
    Loader =
        (tools::ppc::hasPPCAbiArg(Args, "elfv1")) ? "ld64.so.1" : "ld64.so.2";
    break;
  case llvm::Triple::sparc:
  case llvm::Triple::sparcel:
    LibDir = "lib";
    Loader = "ld-linux.so.2";
    break;
  case llvm::Triple::sparcv9:
    LibDir = "lib64";
    Loader = "ld-linux.so.2";
    break;
  case llvm::Triple::systemz:
    LibDir = "lib";
    Loader = "ld64.so.1";
    break;
  case llvm::Triple::x86:
    LibDir = "lib";
    Loader = "ld-linux.so.2";
    break;
  case llvm::Triple::x86_64: {
    bool X32 = Triple.getEnvironment() == llvm::Triple::GNUX32;

    LibDir = X32 ? "libx32" : "lib64";
    Loader = X32 ? "ld-linux-x32.so.2" : "ld-linux-x86-64.so.2";
    break;
  }
  }

  if (Distro == Distro::Exherbo && (Triple.getVendor() == llvm::Triple::UnknownVendor ||
                                    Triple.getVendor() == llvm::Triple::PC))
    return "/usr/" + Triple.str() + "/lib/" + Loader;
  return "/" + LibDir + "/" + Loader;
}

void Linux::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                      ArgStringList &CC1Args) const {
  const Driver &D = getDriver();
  std::string SysRoot = computeSysRoot();

  if (DriverArgs.hasArg(options::OPT_nostdinc))
    return;

  if (!DriverArgs.hasArg(options::OPT_nostdlibinc))
    addSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/local/include");

  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
    SmallString<128> P(D.ResourceDir);
    llvm::sys::path::append(P, "include");
    addSystemInclude(DriverArgs, CC1Args, P);
  }

  if (DriverArgs.hasArg(options::OPT_nostdlibinc))
    return;

  // Check for configure-time C include directories.
  StringRef CIncludeDirs(C_INCLUDE_DIRS);
  if (CIncludeDirs != "") {
    SmallVector<StringRef, 5> dirs;
    CIncludeDirs.split(dirs, ":");
    for (StringRef dir : dirs) {
      StringRef Prefix =
          llvm::sys::path::is_absolute(dir) ? StringRef(SysRoot) : "";
      addExternCSystemInclude(DriverArgs, CC1Args, Prefix + dir);
    }
    return;
  }

  // Lacking those, try to detect the correct set of system includes for the
  // target triple.

  // Add include directories specific to the selected multilib set and multilib.
  if (GCCInstallation.isValid()) {
    const auto &Callback = Multilibs.includeDirsCallback();
    if (Callback) {
      for (const auto &Path : Callback(GCCInstallation.getMultilib()))
        addExternCSystemIncludeIfExists(
            DriverArgs, CC1Args, GCCInstallation.getInstallPath() + Path);
    }
  }

  // Implement generic Debian multiarch support.
  const StringRef X86_64MultiarchIncludeDirs[] = {
      "/usr/include/x86_64-linux-gnu",

      // FIXME: These are older forms of multiarch. It's not clear that they're
      // in use in any released version of Debian, so we should consider
      // removing them.
      "/usr/include/i686-linux-gnu/64", "/usr/include/i486-linux-gnu/64"};
  const StringRef X86MultiarchIncludeDirs[] = {
      "/usr/include/i386-linux-gnu",

      // FIXME: These are older forms of multiarch. It's not clear that they're
      // in use in any released version of Debian, so we should consider
      // removing them.
      "/usr/include/x86_64-linux-gnu/32", "/usr/include/i686-linux-gnu",
      "/usr/include/i486-linux-gnu"};
  const StringRef AArch64MultiarchIncludeDirs[] = {
      "/usr/include/aarch64-linux-gnu"};
  const StringRef ARMMultiarchIncludeDirs[] = {
      "/usr/include/arm-linux-gnueabi"};
  const StringRef ARMHFMultiarchIncludeDirs[] = {
      "/usr/include/arm-linux-gnueabihf"};
  const StringRef ARMEBMultiarchIncludeDirs[] = {
      "/usr/include/armeb-linux-gnueabi"};
  const StringRef ARMEBHFMultiarchIncludeDirs[] = {
      "/usr/include/armeb-linux-gnueabihf"};
  const StringRef MIPSMultiarchIncludeDirs[] = {"/usr/include/mips-linux-gnu"};
  const StringRef MIPSELMultiarchIncludeDirs[] = {
      "/usr/include/mipsel-linux-gnu"};
  const StringRef MIPS64MultiarchIncludeDirs[] = {
      "/usr/include/mips64-linux-gnu", "/usr/include/mips64-linux-gnuabi64"};
  const StringRef MIPS64ELMultiarchIncludeDirs[] = {
      "/usr/include/mips64el-linux-gnu",
      "/usr/include/mips64el-linux-gnuabi64"};
  const StringRef PPCMultiarchIncludeDirs[] = {
      "/usr/include/powerpc-linux-gnu"};
  const StringRef PPC64MultiarchIncludeDirs[] = {
      "/usr/include/powerpc64-linux-gnu"};
  const StringRef PPC64LEMultiarchIncludeDirs[] = {
      "/usr/include/powerpc64le-linux-gnu"};
  const StringRef SparcMultiarchIncludeDirs[] = {
      "/usr/include/sparc-linux-gnu"};
  const StringRef Sparc64MultiarchIncludeDirs[] = {
      "/usr/include/sparc64-linux-gnu"};
  const StringRef SYSTEMZMultiarchIncludeDirs[] = {
      "/usr/include/s390x-linux-gnu"};
  ArrayRef<StringRef> MultiarchIncludeDirs;
  switch (getTriple().getArch()) {
  case llvm::Triple::x86_64:
    MultiarchIncludeDirs = X86_64MultiarchIncludeDirs;
    break;
  case llvm::Triple::x86:
    MultiarchIncludeDirs = X86MultiarchIncludeDirs;
    break;
  case llvm::Triple::aarch64:
  case llvm::Triple::aarch64_be:
    MultiarchIncludeDirs = AArch64MultiarchIncludeDirs;
    break;
  case llvm::Triple::arm:
  case llvm::Triple::thumb:
    if (getTriple().getEnvironment() == llvm::Triple::GNUEABIHF)
      MultiarchIncludeDirs = ARMHFMultiarchIncludeDirs;
    else
      MultiarchIncludeDirs = ARMMultiarchIncludeDirs;
    break;
  case llvm::Triple::armeb:
  case llvm::Triple::thumbeb:
    if (getTriple().getEnvironment() == llvm::Triple::GNUEABIHF)
      MultiarchIncludeDirs = ARMEBHFMultiarchIncludeDirs;
    else
      MultiarchIncludeDirs = ARMEBMultiarchIncludeDirs;
    break;
  case llvm::Triple::mips:
    MultiarchIncludeDirs = MIPSMultiarchIncludeDirs;
    break;
  case llvm::Triple::mipsel:
    MultiarchIncludeDirs = MIPSELMultiarchIncludeDirs;
    break;
  case llvm::Triple::mips64:
    MultiarchIncludeDirs = MIPS64MultiarchIncludeDirs;
    break;
  case llvm::Triple::mips64el:
    MultiarchIncludeDirs = MIPS64ELMultiarchIncludeDirs;
    break;
  case llvm::Triple::ppc:
    MultiarchIncludeDirs = PPCMultiarchIncludeDirs;
    break;
  case llvm::Triple::ppc64:
    MultiarchIncludeDirs = PPC64MultiarchIncludeDirs;
    break;
  case llvm::Triple::ppc64le:
    MultiarchIncludeDirs = PPC64LEMultiarchIncludeDirs;
    break;
  case llvm::Triple::sparc:
    MultiarchIncludeDirs = SparcMultiarchIncludeDirs;
    break;
  case llvm::Triple::sparcv9:
    MultiarchIncludeDirs = Sparc64MultiarchIncludeDirs;
    break;
  case llvm::Triple::systemz:
    MultiarchIncludeDirs = SYSTEMZMultiarchIncludeDirs;
    break;
  default:
    break;
  }
  for (StringRef Dir : MultiarchIncludeDirs) {
    if (D.getVFS().exists(SysRoot + Dir)) {
      addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + Dir);
      break;
    }
  }

  if (getTriple().getOS() == llvm::Triple::RTEMS)
    return;

  // Add an include of '/include' directly. This isn't provided by default by
  // system GCCs, but is often used with cross-compiling GCCs, and harmless to
  // add even when Clang is acting as-if it were a system compiler.
  addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/include");

  addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/include");
}

static std::string DetectLibcxxIncludePath(StringRef base) {
  std::error_code EC;
  int MaxVersion = 0;
  std::string MaxVersionString = "";
  for (llvm::sys::fs::directory_iterator LI(base, EC), LE; !EC && LI != LE;
       LI = LI.increment(EC)) {
    StringRef VersionText = llvm::sys::path::filename(LI->path());
    int Version;
    if (VersionText[0] == 'v' &&
        !VersionText.slice(1, StringRef::npos).getAsInteger(10, Version)) {
      if (Version > MaxVersion) {
        MaxVersion = Version;
        MaxVersionString = VersionText;
      }
    }
  }
  return MaxVersion ? (base + "/" + MaxVersionString).str() : "";
}

std::string Linux::findLibCxxIncludePath() const {
  const std::string LibCXXIncludePathCandidates[] = {
      DetectLibcxxIncludePath(getDriver().Dir + "/../include/c++"),
      // If this is a development, non-installed, clang, libcxx will
      // not be found at ../include/c++ but it likely to be found at
      // one of the following two locations:
      DetectLibcxxIncludePath(getDriver().SysRoot + "/usr/local/include/c++"),
      DetectLibcxxIncludePath(getDriver().SysRoot + "/usr/include/c++") };
  for (const auto &IncludePath : LibCXXIncludePathCandidates) {
    if (IncludePath.empty() || !getVFS().exists(IncludePath))
      continue;
    // Use the first candidate that exists.
    return IncludePath;
  }
  return "";
}

void Linux::addLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                     llvm::opt::ArgStringList &CC1Args) const {
  // We need a detected GCC installation on Linux to provide libstdc++'s
  // headers.
  if (!GCCInstallation.isValid())
    return;

  // By default, look for the C++ headers in an include directory adjacent to
  // the lib directory of the GCC installation. Note that this is expect to be
  // equivalent to '/usr/include/c++/X.Y' in almost all cases.
  StringRef LibDir = GCCInstallation.getParentLibPath();
  StringRef InstallDir = GCCInstallation.getInstallPath();
  StringRef TripleStr = GCCInstallation.getTriple().str();
  const Multilib &Multilib = GCCInstallation.getMultilib();
  const std::string GCCMultiarchTriple = getMultiarchTriple(
      getDriver(), GCCInstallation.getTriple(), getDriver().SysRoot);
  const std::string TargetMultiarchTriple =
      getMultiarchTriple(getDriver(), getTriple(), getDriver().SysRoot);
  const GCCVersion &Version = GCCInstallation.getVersion();

  // The primary search for libstdc++ supports multiarch variants.
  if (addLibStdCXXIncludePaths(LibDir.str() + "/../include",
                               "/c++/" + Version.Text, TripleStr,
                               GCCMultiarchTriple, TargetMultiarchTriple,
                               Multilib.includeSuffix(), DriverArgs, CC1Args))
    return;

  // Otherwise, fall back on a bunch of options which don't use multiarch
  // layouts for simplicity.
  const std::string LibStdCXXIncludePathCandidates[] = {
      // Gentoo is weird and places its headers inside the GCC install,
      // so if the first attempt to find the headers fails, try these patterns.
      InstallDir.str() + "/include/g++-v" + Version.Text,
      InstallDir.str() + "/include/g++-v" + Version.MajorStr + "." +
          Version.MinorStr,
      InstallDir.str() + "/include/g++-v" + Version.MajorStr,
      // Android standalone toolchain has C++ headers in yet another place.
      LibDir.str() + "/../" + TripleStr.str() + "/include/c++/" + Version.Text,
      // Freescale SDK C++ headers are directly in <sysroot>/usr/include/c++,
      // without a subdirectory corresponding to the gcc version.
      LibDir.str() + "/../include/c++",
  };

  for (const auto &IncludePath : LibStdCXXIncludePathCandidates) {
    if (addLibStdCXXIncludePaths(IncludePath, /*Suffix*/ "", TripleStr,
                                 /*GCCMultiarchTriple*/ "",
                                 /*TargetMultiarchTriple*/ "",
                                 Multilib.includeSuffix(), DriverArgs, CC1Args))
      break;
  }
}

void Linux::AddCudaIncludeArgs(const ArgList &DriverArgs,
                               ArgStringList &CC1Args) const {
  CudaInstallation.AddCudaIncludeArgs(DriverArgs, CC1Args);
}

void Linux::AddIAMCUIncludeArgs(const ArgList &DriverArgs,
                                ArgStringList &CC1Args) const {
  if (GCCInstallation.isValid()) {
    CC1Args.push_back("-isystem");
    CC1Args.push_back(DriverArgs.MakeArgString(
        GCCInstallation.getParentLibPath() + "/../" +
        GCCInstallation.getTriple().str() + "/include"));
  }
}

bool Linux::isPIEDefault() const { return getSanitizerArgs().requiresPIE(); }

SanitizerMask Linux::getSupportedSanitizers() const {
  const bool IsX86 = getTriple().getArch() == llvm::Triple::x86;
  const bool IsX86_64 = getTriple().getArch() == llvm::Triple::x86_64;
  const bool IsMIPS64 = getTriple().getArch() == llvm::Triple::mips64 ||
                        getTriple().getArch() == llvm::Triple::mips64el;
  const bool IsPowerPC64 = getTriple().getArch() == llvm::Triple::ppc64 ||
                           getTriple().getArch() == llvm::Triple::ppc64le;
  const bool IsAArch64 = getTriple().getArch() == llvm::Triple::aarch64 ||
                         getTriple().getArch() == llvm::Triple::aarch64_be;
  SanitizerMask Res = ToolChain::getSupportedSanitizers();
  Res |= SanitizerKind::Address;
  Res |= SanitizerKind::KernelAddress;
  Res |= SanitizerKind::Vptr;
  Res |= SanitizerKind::SafeStack;
  if (IsX86_64 || IsMIPS64 || IsAArch64)
    Res |= SanitizerKind::DataFlow;
  if (IsX86_64 || IsMIPS64 || IsAArch64)
    Res |= SanitizerKind::Leak;
  if (IsX86_64 || IsMIPS64 || IsAArch64 || IsPowerPC64)
    Res |= SanitizerKind::Thread;
  if (IsX86_64 || IsMIPS64 || IsPowerPC64 || IsAArch64)
    Res |= SanitizerKind::Memory;
  if (IsX86_64 || IsMIPS64)
    Res |= SanitizerKind::Efficiency;
  if (IsX86 || IsX86_64) {
    Res |= SanitizerKind::Function;
  }
  return Res;
}

void Linux::addProfileRTLibs(const llvm::opt::ArgList &Args,
                             llvm::opt::ArgStringList &CmdArgs) const {
  if (!needsProfileRT(Args)) return;

  // Add linker option -u__llvm_runtime_variable to cause runtime
  // initialization module to be linked in.
  if (!Args.hasArg(options::OPT_coverage))
    CmdArgs.push_back(Args.MakeArgString(
        Twine("-u", llvm::getInstrProfRuntimeHookVarName())));
  ToolChain::addProfileRTLibs(Args, CmdArgs);
}

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

Fuchsia::Fuchsia(const Driver &D, const llvm::Triple &Triple,
                 const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {

  getFilePaths().push_back(D.SysRoot + "/lib");
  getFilePaths().push_back(D.ResourceDir + "/lib/fuchsia");
}

Tool *Fuchsia::buildAssembler() const {
  return new tools::gnutools::Assembler(*this);
}

Tool *Fuchsia::buildLinker() const {
  return new tools::fuchsia::Linker(*this);
}

ToolChain::RuntimeLibType Fuchsia::GetRuntimeLibType(
    const ArgList &Args) const {
  if (Arg *A = Args.getLastArg(options::OPT_rtlib_EQ)) {
    StringRef Value = A->getValue();
    if (Value != "compiler-rt")
      getDriver().Diag(diag::err_drv_invalid_rtlib_name)
        << A->getAsString(Args);
  }

  return ToolChain::RLT_CompilerRT;
}

ToolChain::CXXStdlibType
Fuchsia::GetCXXStdlibType(const ArgList &Args) const {
  if (Arg *A = Args.getLastArg(options::OPT_stdlib_EQ)) {
    StringRef Value = A->getValue();
    if (Value != "libc++")
      getDriver().Diag(diag::err_drv_invalid_stdlib_name)
        << A->getAsString(Args);
  }

  return ToolChain::CST_Libcxx;
}

void Fuchsia::addClangTargetOptions(const ArgList &DriverArgs,
                                    ArgStringList &CC1Args) const {
  if (DriverArgs.hasFlag(options::OPT_fuse_init_array,
                         options::OPT_fno_use_init_array, true))
    CC1Args.push_back("-fuse-init-array");
}

void Fuchsia::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                        ArgStringList &CC1Args) const {
  const Driver &D = getDriver();

  if (DriverArgs.hasArg(options::OPT_nostdinc))
    return;

  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
    SmallString<128> P(D.ResourceDir);
    llvm::sys::path::append(P, "include");
    addSystemInclude(DriverArgs, CC1Args, P);
  }

  if (DriverArgs.hasArg(options::OPT_nostdlibinc))
    return;

  // Check for configure-time C include directories.
  StringRef CIncludeDirs(C_INCLUDE_DIRS);
  if (CIncludeDirs != "") {
    SmallVector<StringRef, 5> dirs;
    CIncludeDirs.split(dirs, ":");
    for (StringRef dir : dirs) {
      StringRef Prefix =
          llvm::sys::path::is_absolute(dir) ? StringRef(D.SysRoot) : "";
      addExternCSystemInclude(DriverArgs, CC1Args, Prefix + dir);
    }
    return;
  }

  addExternCSystemInclude(DriverArgs, CC1Args, D.SysRoot + "/include");
}

std::string Fuchsia::findLibCxxIncludePath() const {
  return getDriver().SysRoot + "/include/c++/v1";
}

void Fuchsia::AddCXXStdlibLibArgs(const ArgList &Args,
                                  ArgStringList &CmdArgs) const {
  (void) GetCXXStdlibType(Args);
  CmdArgs.push_back("-lc++");
  CmdArgs.push_back("-lc++abi");
  CmdArgs.push_back("-lunwind");
}

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

DragonFly::DragonFly(const Driver &D, const llvm::Triple &Triple,
                     const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {

  // 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/gcc50");
}

Tool *DragonFly::buildAssembler() const {
  return new tools::dragonfly::Assembler(*this);
}

Tool *DragonFly::buildLinker() const {
  return new tools::dragonfly::Linker(*this);
}

/// CUDA toolchain.  Our assembler is ptxas, and our "linker" is fatbinary,
/// which isn't properly a linker but nonetheless performs the step of stitching
/// together object files from the assembler into a single blob.

CudaToolChain::CudaToolChain(const Driver &D, const llvm::Triple &Triple,
                             const ToolChain &HostTC, const ArgList &Args)
    : ToolChain(D, Triple, Args), HostTC(HostTC),
      CudaInstallation(D, HostTC.getTriple(), Args) {
  if (CudaInstallation.isValid())
    getProgramPaths().push_back(CudaInstallation.getBinPath());
}

void CudaToolChain::addClangTargetOptions(
    const llvm::opt::ArgList &DriverArgs,
    llvm::opt::ArgStringList &CC1Args) const {
  HostTC.addClangTargetOptions(DriverArgs, CC1Args);

  CC1Args.push_back("-fcuda-is-device");

  if (DriverArgs.hasFlag(options::OPT_fcuda_flush_denormals_to_zero,
                         options::OPT_fno_cuda_flush_denormals_to_zero, false))
    CC1Args.push_back("-fcuda-flush-denormals-to-zero");

  if (DriverArgs.hasFlag(options::OPT_fcuda_approx_transcendentals,
                         options::OPT_fno_cuda_approx_transcendentals, false))
    CC1Args.push_back("-fcuda-approx-transcendentals");

  if (DriverArgs.hasArg(options::OPT_nocudalib))
    return;

  StringRef GpuArch = DriverArgs.getLastArgValue(options::OPT_march_EQ);
  assert(!GpuArch.empty() && "Must have an explicit GPU arch.");
  std::string LibDeviceFile = CudaInstallation.getLibDeviceFile(GpuArch);

  if (LibDeviceFile.empty()) {
    getDriver().Diag(diag::err_drv_no_cuda_libdevice) << GpuArch;
    return;
  }

  CC1Args.push_back("-mlink-cuda-bitcode");
  CC1Args.push_back(DriverArgs.MakeArgString(LibDeviceFile));

  // Libdevice in CUDA-7.0 requires PTX version that's more recent
  // than LLVM defaults to. Use PTX4.2 which is the PTX version that
  // came with CUDA-7.0.
  CC1Args.push_back("-target-feature");
  CC1Args.push_back("+ptx42");
}

void CudaToolChain::AddCudaIncludeArgs(const ArgList &DriverArgs,
                                       ArgStringList &CC1Args) const {
  // Check our CUDA version if we're going to include the CUDA headers.
  if (!DriverArgs.hasArg(options::OPT_nocudainc) &&
      !DriverArgs.hasArg(options::OPT_no_cuda_version_check)) {
    StringRef Arch = DriverArgs.getLastArgValue(options::OPT_march_EQ);
    assert(!Arch.empty() && "Must have an explicit GPU arch.");
    CudaInstallation.CheckCudaVersionSupportsArch(StringToCudaArch(Arch));
  }
  CudaInstallation.AddCudaIncludeArgs(DriverArgs, CC1Args);
}

llvm::opt::DerivedArgList *
CudaToolChain::TranslateArgs(const llvm::opt::DerivedArgList &Args,
                             StringRef BoundArch,
                             Action::OffloadKind DeviceOffloadKind) const {
  DerivedArgList *DAL =
      HostTC.TranslateArgs(Args, BoundArch, DeviceOffloadKind);
  if (!DAL)
    DAL = new DerivedArgList(Args.getBaseArgs());

  const OptTable &Opts = getDriver().getOpts();

  for (Arg *A : Args) {
    if (A->getOption().matches(options::OPT_Xarch__)) {
      // Skip this argument unless the architecture matches BoundArch
      if (BoundArch.empty() || A->getValue(0) != BoundArch)
        continue;

      unsigned Index = Args.getBaseArgs().MakeIndex(A->getValue(1));
      unsigned Prev = Index;
      std::unique_ptr<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().hasFlag(options::DriverOption)) {
        getDriver().Diag(diag::err_drv_invalid_Xarch_argument_isdriver)
            << A->getAsString(Args);
        continue;
      }
      XarchArg->setBaseArg(A);
      A = XarchArg.release();
      DAL->AddSynthesizedArg(A);
    }
    DAL->append(A);
  }

  if (!BoundArch.empty()) {
    DAL->eraseArg(options::OPT_march_EQ);
    DAL->AddJoinedArg(nullptr, Opts.getOption(options::OPT_march_EQ), BoundArch);
  }
  return DAL;
}

Tool *CudaToolChain::buildAssembler() const {
  return new tools::NVPTX::Assembler(*this);
}

Tool *CudaToolChain::buildLinker() const {
  return new tools::NVPTX::Linker(*this);
}

void CudaToolChain::addClangWarningOptions(ArgStringList &CC1Args) const {
  HostTC.addClangWarningOptions(CC1Args);
}

ToolChain::CXXStdlibType
CudaToolChain::GetCXXStdlibType(const ArgList &Args) const {
  return HostTC.GetCXXStdlibType(Args);
}

void CudaToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                              ArgStringList &CC1Args) const {
  HostTC.AddClangSystemIncludeArgs(DriverArgs, CC1Args);
}

void CudaToolChain::AddClangCXXStdlibIncludeArgs(const ArgList &Args,
                                                 ArgStringList &CC1Args) const {
  HostTC.AddClangCXXStdlibIncludeArgs(Args, CC1Args);
}

void CudaToolChain::AddIAMCUIncludeArgs(const ArgList &Args,
                                        ArgStringList &CC1Args) const {
  HostTC.AddIAMCUIncludeArgs(Args, CC1Args);
}

SanitizerMask CudaToolChain::getSupportedSanitizers() const {
  // The CudaToolChain only supports sanitizers in the sense that it allows
  // sanitizer arguments on the command line if they are supported by the host
  // toolchain. The CudaToolChain will actually ignore any command line
  // arguments for any of these "supported" sanitizers. That means that no
  // sanitization of device code is actually supported at this time.
  //
  // This behavior is necessary because the host and device toolchains
  // invocations often share the command line, so the device toolchain must
  // tolerate flags meant only for the host toolchain.
  return HostTC.getSupportedSanitizers();
}

VersionTuple CudaToolChain::computeMSVCVersion(const Driver *D,
                                               const ArgList &Args) const {
  return HostTC.computeMSVCVersion(D, Args);
}

/// XCore tool chain
XCoreToolChain::XCoreToolChain(const Driver &D, const llvm::Triple &Triple,
                               const ArgList &Args)
    : ToolChain(D, Triple, Args) {
  // ProgramPaths are found via 'PATH' environment variable.
}

Tool *XCoreToolChain::buildAssembler() const {
  return new tools::XCore::Assembler(*this);
}

Tool *XCoreToolChain::buildLinker() const {
  return new tools::XCore::Linker(*this);
}

bool XCoreToolChain::isPICDefault() const { return false; }

bool XCoreToolChain::isPIEDefault() const { return false; }

bool XCoreToolChain::isPICDefaultForced() const { return false; }

bool XCoreToolChain::SupportsProfiling() const { return false; }

bool XCoreToolChain::hasBlocksRuntime() const { return false; }

void XCoreToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                               ArgStringList &CC1Args) const {
  if (DriverArgs.hasArg(options::OPT_nostdinc) ||
      DriverArgs.hasArg(options::OPT_nostdlibinc))
    return;
  if (const char *cl_include_dir = getenv("XCC_C_INCLUDE_PATH")) {
    SmallVector<StringRef, 4> Dirs;
    const char EnvPathSeparatorStr[] = {llvm::sys::EnvPathSeparator, '\0'};
    StringRef(cl_include_dir).split(Dirs, StringRef(EnvPathSeparatorStr));
    ArrayRef<StringRef> DirVec(Dirs);
    addSystemIncludes(DriverArgs, CC1Args, DirVec);
  }
}

void XCoreToolChain::addClangTargetOptions(const ArgList &DriverArgs,
                                           ArgStringList &CC1Args) const {
  CC1Args.push_back("-nostdsysteminc");
}

void XCoreToolChain::AddClangCXXStdlibIncludeArgs(
    const ArgList &DriverArgs, ArgStringList &CC1Args) const {
  if (DriverArgs.hasArg(options::OPT_nostdinc) ||
      DriverArgs.hasArg(options::OPT_nostdlibinc) ||
      DriverArgs.hasArg(options::OPT_nostdincxx))
    return;
  if (const char *cl_include_dir = getenv("XCC_CPLUS_INCLUDE_PATH")) {
    SmallVector<StringRef, 4> Dirs;
    const char EnvPathSeparatorStr[] = {llvm::sys::EnvPathSeparator, '\0'};
    StringRef(cl_include_dir).split(Dirs, StringRef(EnvPathSeparatorStr));
    ArrayRef<StringRef> DirVec(Dirs);
    addSystemIncludes(DriverArgs, CC1Args, DirVec);
  }
}

void XCoreToolChain::AddCXXStdlibLibArgs(const ArgList &Args,
                                         ArgStringList &CmdArgs) const {
  // We don't output any lib args. This is handled by xcc.
}

MyriadToolChain::MyriadToolChain(const Driver &D, const llvm::Triple &Triple,
                                 const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {
  // If a target of 'sparc-myriad-elf' is specified to clang, it wants to use
  // 'sparc-myriad--elf' (note the unknown OS) as the canonical triple.
  // This won't work to find gcc. Instead we give the installation detector an
  // extra triple, which is preferable to further hacks of the logic that at
  // present is based solely on getArch(). In particular, it would be wrong to
  // choose the myriad installation when targeting a non-myriad sparc install.
  switch (Triple.getArch()) {
  default:
    D.Diag(diag::err_target_unsupported_arch) << Triple.getArchName()
                                              << "myriad";
  case llvm::Triple::sparc:
  case llvm::Triple::sparcel:
  case llvm::Triple::shave:
    GCCInstallation.init(Triple, Args, {"sparc-myriad-elf"});
  }

  if (GCCInstallation.isValid()) {
    // This directory contains crt{i,n,begin,end}.o as well as libgcc.
    // These files are tied to a particular version of gcc.
    SmallString<128> CompilerSupportDir(GCCInstallation.getInstallPath());
    addPathIfExists(D, CompilerSupportDir, getFilePaths());
  }
  // libstd++ and libc++ must both be found in this one place.
  addPathIfExists(D, D.Dir + "/../sparc-myriad-elf/lib", getFilePaths());
}

MyriadToolChain::~MyriadToolChain() {}

void MyriadToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                                ArgStringList &CC1Args) const {
  if (!DriverArgs.hasArg(options::OPT_nostdinc))
    addSystemInclude(DriverArgs, CC1Args, getDriver().SysRoot + "/include");
}

std::string MyriadToolChain::findLibCxxIncludePath() const {
  std::string Path(getDriver().getInstalledDir());
  return Path + "/../include/c++/v1";
}

void MyriadToolChain::addLibStdCxxIncludePaths(
    const llvm::opt::ArgList &DriverArgs,
    llvm::opt::ArgStringList &CC1Args) const {
  StringRef LibDir = GCCInstallation.getParentLibPath();
  const GCCVersion &Version = GCCInstallation.getVersion();
  StringRef TripleStr = GCCInstallation.getTriple().str();
  const Multilib &Multilib = GCCInstallation.getMultilib();
  addLibStdCXXIncludePaths(
      LibDir.str() + "/../" + TripleStr.str() + "/include/c++/" + Version.Text,
      "", TripleStr, "", "", Multilib.includeSuffix(), DriverArgs, CC1Args);
}

// MyriadToolChain handles several triples:
//  {shave,sparc{,el}}-myriad-{rtems,unknown}-elf
Tool *MyriadToolChain::SelectTool(const JobAction &JA) const {
  // The inherited method works fine if not targeting the SHAVE.
  if (!isShaveCompilation(getTriple()))
    return ToolChain::SelectTool(JA);
  switch (JA.getKind()) {
  case Action::PreprocessJobClass:
  case Action::CompileJobClass:
    if (!Compiler)
      Compiler.reset(new tools::SHAVE::Compiler(*this));
    return Compiler.get();
  case Action::AssembleJobClass:
    if (!Assembler)
      Assembler.reset(new tools::SHAVE::Assembler(*this));
    return Assembler.get();
  default:
    return ToolChain::getTool(JA.getKind());
  }
}

Tool *MyriadToolChain::buildLinker() const {
  return new tools::Myriad::Linker(*this);
}

SanitizerMask MyriadToolChain::getSupportedSanitizers() const {
  return SanitizerKind::Address;
}

WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
                         const llvm::opt::ArgList &Args)
  : ToolChain(D, Triple, Args) {

  assert(Triple.isArch32Bit() != Triple.isArch64Bit());
  getFilePaths().push_back(
      getDriver().SysRoot + "/lib" + (Triple.isArch32Bit() ? "32" : "64"));
}

bool WebAssembly::IsMathErrnoDefault() const { return false; }

bool WebAssembly::IsObjCNonFragileABIDefault() const { return true; }

bool WebAssembly::UseObjCMixedDispatch() const { return true; }

bool WebAssembly::isPICDefault() const { return false; }

bool WebAssembly::isPIEDefault() const { return false; }

bool WebAssembly::isPICDefaultForced() const { return false; }

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

// TODO: Support Objective C stuff.
bool WebAssembly::SupportsObjCGC() const { return false; }

bool WebAssembly::hasBlocksRuntime() const { return false; }

// TODO: Support profiling.
bool WebAssembly::SupportsProfiling() const { return false; }

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

void WebAssembly::addClangTargetOptions(const ArgList &DriverArgs,
                                        ArgStringList &CC1Args) const {
  if (DriverArgs.hasFlag(options::OPT_fuse_init_array,
                         options::OPT_fno_use_init_array, true))
    CC1Args.push_back("-fuse-init-array");
}

ToolChain::RuntimeLibType WebAssembly::GetDefaultRuntimeLibType() const {
  return ToolChain::RLT_CompilerRT;
}

ToolChain::CXXStdlibType WebAssembly::GetCXXStdlibType(const ArgList &Args) const {
  return ToolChain::CST_Libcxx;
}

void WebAssembly::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                            ArgStringList &CC1Args) const {
  if (!DriverArgs.hasArg(options::OPT_nostdinc))
    addSystemInclude(DriverArgs, CC1Args, getDriver().SysRoot + "/include");
}

void WebAssembly::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                               ArgStringList &CC1Args) const {
  if (!DriverArgs.hasArg(options::OPT_nostdlibinc) &&
      !DriverArgs.hasArg(options::OPT_nostdincxx))
    addSystemInclude(DriverArgs, CC1Args,
                     getDriver().SysRoot + "/include/c++/v1");
}

Tool *WebAssembly::buildLinker() const {
  return new tools::wasm::Linker(*this);
}

PS4CPU::PS4CPU(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {
  if (Args.hasArg(options::OPT_static))
    D.Diag(diag::err_drv_unsupported_opt_for_target) << "-static" << "PS4";

  // Determine where to find the PS4 libraries. We use SCE_ORBIS_SDK_DIR
  // if it exists; otherwise use the driver's installation path, which
  // should be <SDK_DIR>/host_tools/bin.

  SmallString<512> PS4SDKDir;
  if (const char *EnvValue = getenv("SCE_ORBIS_SDK_DIR")) {
    if (!llvm::sys::fs::exists(EnvValue))
      getDriver().Diag(clang::diag::warn_drv_ps4_sdk_dir) << EnvValue;
    PS4SDKDir = EnvValue;
  } else {
    PS4SDKDir = getDriver().Dir;
    llvm::sys::path::append(PS4SDKDir, "/../../");
  }

  // By default, the driver won't report a warning if it can't find
  // PS4's include or lib directories. This behavior could be changed if
  // -Weverything or -Winvalid-or-nonexistent-directory options are passed.
  // If -isysroot was passed, use that as the SDK base path.
  std::string PrefixDir;
  if (const Arg *A = Args.getLastArg(options::OPT_isysroot)) {
    PrefixDir = A->getValue();
    if (!llvm::sys::fs::exists(PrefixDir))
      getDriver().Diag(clang::diag::warn_missing_sysroot) << PrefixDir;
  } else
    PrefixDir = PS4SDKDir.str();

  SmallString<512> PS4SDKIncludeDir(PrefixDir);
  llvm::sys::path::append(PS4SDKIncludeDir, "target/include");
  if (!Args.hasArg(options::OPT_nostdinc) &&
      !Args.hasArg(options::OPT_nostdlibinc) &&
      !Args.hasArg(options::OPT_isysroot) &&
      !Args.hasArg(options::OPT__sysroot_EQ) &&
      !llvm::sys::fs::exists(PS4SDKIncludeDir)) {
    getDriver().Diag(clang::diag::warn_drv_unable_to_find_directory_expected)
        << "PS4 system headers" << PS4SDKIncludeDir;
  }

  SmallString<512> PS4SDKLibDir(PS4SDKDir);
  llvm::sys::path::append(PS4SDKLibDir, "target/lib");
  if (!Args.hasArg(options::OPT_nostdlib) &&
      !Args.hasArg(options::OPT_nodefaultlibs) &&
      !Args.hasArg(options::OPT__sysroot_EQ) && !Args.hasArg(options::OPT_E) &&
      !Args.hasArg(options::OPT_c) && !Args.hasArg(options::OPT_S) &&
      !Args.hasArg(options::OPT_emit_ast) &&
      !llvm::sys::fs::exists(PS4SDKLibDir)) {
    getDriver().Diag(clang::diag::warn_drv_unable_to_find_directory_expected)
        << "PS4 system libraries" << PS4SDKLibDir;
    return;
  }
  getFilePaths().push_back(PS4SDKLibDir.str());
}

Tool *PS4CPU::buildAssembler() const {
  return new tools::PS4cpu::Assemble(*this);
}

Tool *PS4CPU::buildLinker() const { return new tools::PS4cpu::Link(*this); }

bool PS4CPU::isPICDefault() const { return true; }

bool PS4CPU::HasNativeLLVMSupport() const { return true; }

SanitizerMask PS4CPU::getSupportedSanitizers() const {
  SanitizerMask Res = ToolChain::getSupportedSanitizers();
  Res |= SanitizerKind::Address;
  Res |= SanitizerKind::Vptr;
  return Res;
}

Contiki::Contiki(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
    : Generic_ELF(D, Triple, Args) {}

SanitizerMask Contiki::getSupportedSanitizers() const {
  const bool IsX86 = getTriple().getArch() == llvm::Triple::x86;
  SanitizerMask Res = ToolChain::getSupportedSanitizers();
  if (IsX86)
    Res |= SanitizerKind::SafeStack;
  return Res;
}

/// AVR Toolchain
AVRToolChain::AVRToolChain(const Driver &D, const llvm::Triple &Triple,
                           const ArgList &Args)
  : Generic_ELF(D, Triple, Args) { }
Tool *AVRToolChain::buildLinker() const {
  return new tools::AVR::Linker(*this);
}
// End AVR