text: //===--- Gnu.cpp - Gnu Tool and ToolChain Implementations -------*- C++ -*-===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  
  #include "Gnu.h"
  #include "Arch/ARM.h"
  #include "Arch/Mips.h"
  #include "Arch/PPC.h"
  #include "Arch/RISCV.h"
  #include "Arch/Sparc.h"
  #include "Arch/SystemZ.h"
  #include "CommonArgs.h"
  #include "Linux.h"
  #include "clang/Config/config.h" // for GCC_INSTALL_PREFIX
  #include "clang/Driver/Compilation.h"
  #include "clang/Driver/Driver.h"
  #include "clang/Driver/DriverDiagnostic.h"
  #include "clang/Driver/Options.h"
  #include "clang/Driver/Tool.h"
  #include "clang/Driver/ToolChain.h"
  #include "llvm/Option/ArgList.h"
  #include "llvm/Support/CodeGen.h"
  #include "llvm/Support/Path.h"
  #include "llvm/Support/TargetParser.h"
  #include "llvm/Support/VirtualFileSystem.h"
  #include <system_error>
  
  using namespace clang::driver;
  using namespace clang::driver::toolchains;
  using namespace clang;
  using namespace llvm::opt;
  
  using tools::addMultilibFlag;
  
  void tools::GnuTool::anchor() {}
  
  static bool forwardToGCC(const Option &O) {
    // Don't forward inputs from the original command line.  They are added from
    // InputInfoList.
    return O.getKind() != Option::InputClass &&
           !O.hasFlag(options::DriverOption) && !O.hasFlag(options::LinkerInput);
  }
  
  // Switch CPU names not recognized by GNU assembler to a close CPU that it does
  // recognize, instead of a lower march from being picked in the absence of a cpu
  // flag.
  static void normalizeCPUNamesForAssembler(const ArgList &Args,
                                            ArgStringList &CmdArgs) {
    if (Arg *A = Args.getLastArg(options::OPT_mcpu_EQ)) {
      StringRef CPUArg(A->getValue());
      if (CPUArg.equals_lower("krait"))
        CmdArgs.push_back("-mcpu=cortex-a15");
      else if(CPUArg.equals_lower("kryo"))
        CmdArgs.push_back("-mcpu=cortex-a57");
      else
        Args.AddLastArg(CmdArgs, options::OPT_mcpu_EQ);
    }
  }
  
  void tools::gcc::Common::ConstructJob(Compilation &C, const JobAction &JA,
                                        const InputInfo &Output,
                                        const InputInfoList &Inputs,
                                        const ArgList &Args,
                                        const char *LinkingOutput) const {
    const Driver &D = getToolChain().getDriver();
    ArgStringList CmdArgs;
  
    for (const auto &A : Args) {
      if (forwardToGCC(A->getOption())) {
        // It is unfortunate that we have to claim here, as this means
        // we will basically never report anything interesting for
        // platforms using a generic gcc, even if we are just using gcc
        // to get to the assembler.
        A->claim();
  
        // Don't forward any -g arguments to assembly steps.
        if (isa<AssembleJobAction>(JA) &&
            A->getOption().matches(options::OPT_g_Group))
          continue;
  
        // Don't forward any -W arguments to assembly and link steps.
        if ((isa<AssembleJobAction>(JA) || isa<LinkJobAction>(JA)) &&
            A->getOption().matches(options::OPT_W_Group))
          continue;
  
        // Don't forward -mno-unaligned-access since GCC doesn't understand
        // it and because it doesn't affect the assembly or link steps.
        if ((isa<AssembleJobAction>(JA) || isa<LinkJobAction>(JA)) &&
            (A->getOption().matches(options::OPT_munaligned_access) ||
             A->getOption().matches(options::OPT_mno_unaligned_access)))
          continue;
  
        A->render(Args, CmdArgs);
      }
    }
  
    RenderExtraToolArgs(JA, CmdArgs);
  
    // If using a driver driver, force the arch.
    if (getToolChain().getTriple().isOSDarwin()) {
      CmdArgs.push_back("-arch");
      CmdArgs.push_back(
          Args.MakeArgString(getToolChain().getDefaultUniversalArchName()));
    }
  
    // Try to force gcc to match the tool chain we want, if we recognize
    // the arch.
    //
    // FIXME: The triple class should directly provide the information we want
    // here.
    switch (getToolChain().getArch()) {
    default:
      break;
    case llvm::Triple::x86:
    case llvm::Triple::ppc:
      CmdArgs.push_back("-m32");
      break;
    case llvm::Triple::x86_64:
    case llvm::Triple::ppc64:
    case llvm::Triple::ppc64le:
      CmdArgs.push_back("-m64");
      break;
    case llvm::Triple::sparcel:
      CmdArgs.push_back("-EL");
      break;
    }
  
    if (Output.isFilename()) {
      CmdArgs.push_back("-o");
      CmdArgs.push_back(Output.getFilename());
    } else {
      assert(Output.isNothing() && "Unexpected output");
      CmdArgs.push_back("-fsyntax-only");
    }
  
    Args.AddAllArgValues(CmdArgs, options::OPT_Wa_COMMA, options::OPT_Xassembler);
  
    // Only pass -x if gcc will understand it; otherwise hope gcc
    // understands the suffix correctly. The main use case this would go
    // wrong in is for linker inputs if they happened to have an odd
    // suffix; really the only way to get this to happen is a command
    // like '-x foobar a.c' which will treat a.c like a linker input.
    //
    // FIXME: For the linker case specifically, can we safely convert
    // inputs into '-Wl,' options?
    for (const auto &II : Inputs) {
      // Don't try to pass LLVM or AST inputs to a generic gcc.
      if (types::isLLVMIR(II.getType()))
        D.Diag(clang::diag::err_drv_no_linker_llvm_support)
            << getToolChain().getTripleString();
      else if (II.getType() == types::TY_AST)
        D.Diag(diag::err_drv_no_ast_support) << getToolChain().getTripleString();
      else if (II.getType() == types::TY_ModuleFile)
        D.Diag(diag::err_drv_no_module_support)
            << getToolChain().getTripleString();
  
      if (types::canTypeBeUserSpecified(II.getType())) {
        CmdArgs.push_back("-x");
        CmdArgs.push_back(types::getTypeName(II.getType()));
      }
  
      if (II.isFilename())
        CmdArgs.push_back(II.getFilename());
      else {
        const Arg &A = II.getInputArg();
  
        // Reverse translate some rewritten options.
        if (A.getOption().matches(options::OPT_Z_reserved_lib_stdcxx)) {
          CmdArgs.push_back("-lstdc++");
          continue;
        }
  
        // Don't render as input, we need gcc to do the translations.
        A.render(Args, CmdArgs);
      }
    }
  
    const std::string &customGCCName = D.getCCCGenericGCCName();
    const char *GCCName;
    if (!customGCCName.empty())
      GCCName = customGCCName.c_str();
    else if (D.CCCIsCXX()) {
      GCCName = "g++";
    } else
      GCCName = "gcc";
  
    const char *Exec = Args.MakeArgString(getToolChain().GetProgramPath(GCCName));
    C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
  }
  
  void tools::gcc::Preprocessor::RenderExtraToolArgs(
      const JobAction &JA, ArgStringList &CmdArgs) const {
    CmdArgs.push_back("-E");
  }
  
  void tools::gcc::Compiler::RenderExtraToolArgs(const JobAction &JA,
                                                 ArgStringList &CmdArgs) const {
    const Driver &D = getToolChain().getDriver();
  
    switch (JA.getType()) {
    // If -flto, etc. are present then make sure not to force assembly output.
    case types::TY_LLVM_IR:
    case types::TY_LTO_IR:
    case types::TY_LLVM_BC:
    case types::TY_LTO_BC:
      CmdArgs.push_back("-c");
      break;
    // We assume we've got an "integrated" assembler in that gcc will produce an
    // object file itself.
    case types::TY_Object:
      CmdArgs.push_back("-c");
      break;
    case types::TY_PP_Asm:
      CmdArgs.push_back("-S");
      break;
    case types::TY_Nothing:
      CmdArgs.push_back("-fsyntax-only");
      break;
    default:
      D.Diag(diag::err_drv_invalid_gcc_output_type) << getTypeName(JA.getType());
    }
  }
  
  void tools::gcc::Linker::RenderExtraToolArgs(const JobAction &JA,
                                               ArgStringList &CmdArgs) const {
    // The types are (hopefully) good enough.
  }
  
  // On Arm the endianness of the output file is determined by the target and
  // can be overridden by the pseudo-target flags '-mlittle-endian'/'-EL' and
  // '-mbig-endian'/'-EB'. Unlike other targets the flag does not result in a
  // normalized triple so we must handle the flag here.
  static bool isArmBigEndian(const llvm::Triple &Triple,
                             const ArgList &Args) {
    bool IsBigEndian = false;
    switch (Triple.getArch()) {
    case llvm::Triple::armeb:
    case llvm::Triple::thumbeb:
      IsBigEndian = true;
      LLVM_FALLTHROUGH;
    case llvm::Triple::arm:
    case llvm::Triple::thumb:
      if (Arg *A = Args.getLastArg(options::OPT_mlittle_endian,
                                 options::OPT_mbig_endian))
        IsBigEndian = !A->getOption().matches(options::OPT_mlittle_endian);
      break;
    default:
      break;
    }
    return IsBigEndian;
  }
  
  static const char *getLDMOption(const llvm::Triple &T, const ArgList &Args) {
    switch (T.getArch()) {
    case llvm::Triple::x86:
      if (T.isOSIAMCU())
        return "elf_iamcu";
      return "elf_i386";
    case llvm::Triple::aarch64:
      return "aarch64linux";
    case llvm::Triple::aarch64_be:
      return "aarch64linuxb";
    case llvm::Triple::arm:
    case llvm::Triple::thumb:
    case llvm::Triple::armeb:
    case llvm::Triple::thumbeb:
      return isArmBigEndian(T, Args) ? "armelfb_linux_eabi" : "armelf_linux_eabi";
    case llvm::Triple::ppc:
      return "elf32ppclinux";
    case llvm::Triple::ppc64:
      return "elf64ppc";
    case llvm::Triple::ppc64le:
      return "elf64lppc";
    case llvm::Triple::riscv32:
      return "elf32lriscv";
    case llvm::Triple::riscv64:
      return "elf64lriscv";
    case llvm::Triple::sparc:
    case llvm::Triple::sparcel:
      return "elf32_sparc";
    case llvm::Triple::sparcv9:
      return "elf64_sparc";
    case llvm::Triple::mips:
      return "elf32btsmip";
    case llvm::Triple::mipsel:
      return "elf32ltsmip";
    case llvm::Triple::mips64:
      if (tools::mips::hasMipsAbiArg(Args, "n32") ||
          T.getEnvironment() == llvm::Triple::GNUABIN32)
        return "elf32btsmipn32";
      return "elf64btsmip";
    case llvm::Triple::mips64el:
      if (tools::mips::hasMipsAbiArg(Args, "n32") ||
          T.getEnvironment() == llvm::Triple::GNUABIN32)
        return "elf32ltsmipn32";
      return "elf64ltsmip";
    case llvm::Triple::systemz:
      return "elf64_s390";
    case llvm::Triple::x86_64:
      if (T.getEnvironment() == llvm::Triple::GNUX32)
        return "elf32_x86_64";
      return "elf_x86_64";
    default:
      return nullptr;
    }
  }
  
  static bool getPIE(const ArgList &Args, const toolchains::Linux &ToolChain) {
    if (Args.hasArg(options::OPT_shared) || Args.hasArg(options::OPT_static) ||
        Args.hasArg(options::OPT_r))
      return false;
  
    Arg *A = Args.getLastArg(options::OPT_pie, options::OPT_no_pie,
                             options::OPT_nopie);
    if (!A)
      return ToolChain.isPIEDefault();
    return A->getOption().matches(options::OPT_pie);
  }
  
  void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                                             const InputInfo &Output,
                                             const InputInfoList &Inputs,
                                             const ArgList &Args,
                                             const char *LinkingOutput) const {
    const toolchains::Linux &ToolChain =
        static_cast<const toolchains::Linux &>(getToolChain());
    const Driver &D = ToolChain.getDriver();
  
    const llvm::Triple &Triple = getToolChain().getEffectiveTriple();
  
    const llvm::Triple::ArchType Arch = ToolChain.getArch();
    const bool isAndroid = ToolChain.getTriple().isAndroid();
    const bool IsIAMCU = ToolChain.getTriple().isOSIAMCU();
    const bool IsPIE = getPIE(Args, ToolChain);
    const bool IsStaticPIE = Args.hasArg(options::OPT_static_pie);
    const bool HasCRTBeginEndFiles =
        ToolChain.getTriple().hasEnvironment() ||
        (ToolChain.getTriple().getVendor() != llvm::Triple::MipsTechnologies);
  
    ArgStringList CmdArgs;
  
    // Silence warning for "clang -g foo.o -o foo"
    Args.ClaimAllArgs(options::OPT_g_Group);
    // and "clang -emit-llvm foo.o -o foo"
    Args.ClaimAllArgs(options::OPT_emit_llvm);
    // and for "clang -w foo.o -o foo". Other warning options are already
    // handled somewhere else.
    Args.ClaimAllArgs(options::OPT_w);
  
    if (!D.SysRoot.empty())
      CmdArgs.push_back(Args.MakeArgString("--sysroot=" + D.SysRoot));
  
    if (IsPIE)
      CmdArgs.push_back("-pie");
  
    if (IsStaticPIE) {
      CmdArgs.push_back("-static");
      CmdArgs.push_back("-pie");
      CmdArgs.push_back("--no-dynamic-linker");
    }
  
    if (ToolChain.isNoExecStackDefault()) {
      CmdArgs.push_back("-z");
      CmdArgs.push_back("noexecstack");
    }
  
    if (Args.hasArg(options::OPT_rdynamic))
      CmdArgs.push_back("-export-dynamic");
  
    if (Args.hasArg(options::OPT_s))
      CmdArgs.push_back("-s");
  
    if (Triple.isARM() || Triple.isThumb() || Triple.isAArch64()) {
      bool IsBigEndian = isArmBigEndian(Triple, Args);
      if (IsBigEndian)
        arm::appendBE8LinkFlag(Args, CmdArgs, Triple);
      IsBigEndian = IsBigEndian || Arch == llvm::Triple::aarch64_be;
      CmdArgs.push_back(IsBigEndian ? "-EB" : "-EL");
    }
  
    // Most Android ARM64 targets should enable the linker fix for erratum
    // 843419. Only non-Cortex-A53 devices are allowed to skip this flag.
    if (Arch == llvm::Triple::aarch64 && isAndroid) {
      std::string CPU = getCPUName(Args, Triple);
      if (CPU.empty() || CPU == "generic" || CPU == "cortex-a53")
        CmdArgs.push_back("--fix-cortex-a53-843419");
    }
  
    // Android does not allow shared text relocations. Emit a warning if the
    // user's code contains any.
    if (isAndroid)
        CmdArgs.push_back("--warn-shared-textrel");
  
    for (const auto &Opt : ToolChain.ExtraOpts)
      CmdArgs.push_back(Opt.c_str());
  
    CmdArgs.push_back("--eh-frame-hdr");
  
    if (const char *LDMOption = getLDMOption(ToolChain.getTriple(), Args)) {
      CmdArgs.push_back("-m");
      CmdArgs.push_back(LDMOption);
    } else {
      D.Diag(diag::err_target_unknown_triple) << Triple.str();
      return;
    }
  
    if (Args.hasArg(options::OPT_static)) {
      if (Arch == llvm::Triple::arm || Arch == llvm::Triple::armeb ||
          Arch == llvm::Triple::thumb || Arch == llvm::Triple::thumbeb)
        CmdArgs.push_back("-Bstatic");
      else
        CmdArgs.push_back("-static");
    } else if (Args.hasArg(options::OPT_shared)) {
      CmdArgs.push_back("-shared");
    }
  
    if (!Args.hasArg(options::OPT_static)) {
      if (Args.hasArg(options::OPT_rdynamic))
        CmdArgs.push_back("-export-dynamic");
  
      if (!Args.hasArg(options::OPT_shared) && !IsStaticPIE) {
        const std::string Loader =
            D.DyldPrefix + ToolChain.getDynamicLinker(Args);
        CmdArgs.push_back("-dynamic-linker");
        CmdArgs.push_back(Args.MakeArgString(Loader));
      }
    }
  
    CmdArgs.push_back("-o");
    CmdArgs.push_back(Output.getFilename());
  
    if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nostartfiles)) {
      if (!isAndroid && !IsIAMCU) {
        const char *crt1 = nullptr;
        if (!Args.hasArg(options::OPT_shared)) {
          if (Args.hasArg(options::OPT_pg))
            crt1 = "gcrt1.o";
          else if (IsPIE)
            crt1 = "Scrt1.o";
          else if (IsStaticPIE)
            crt1 = "rcrt1.o";
          else
            crt1 = "crt1.o";
        }
        if (crt1)
          CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath(crt1)));
  
        CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crti.o")));
      }
  
      if (IsIAMCU)
        CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crt0.o")));
      else if (HasCRTBeginEndFiles) {
        std::string P;
        if (ToolChain.GetRuntimeLibType(Args) == ToolChain::RLT_CompilerRT &&
            !isAndroid) {
          std::string crtbegin = ToolChain.getCompilerRT(Args, "crtbegin",
                                                         ToolChain::FT_Object);
          if (ToolChain.getVFS().exists(crtbegin))
            P = crtbegin;
        }
        if (P.empty()) {
          const char *crtbegin;
          if (Args.hasArg(options::OPT_static))
            crtbegin = isAndroid ? "crtbegin_static.o" : "crtbeginT.o";
          else if (Args.hasArg(options::OPT_shared))
            crtbegin = isAndroid ? "crtbegin_so.o" : "crtbeginS.o";
          else if (IsPIE || IsStaticPIE)
            crtbegin = isAndroid ? "crtbegin_dynamic.o" : "crtbeginS.o";
          else
            crtbegin = isAndroid ? "crtbegin_dynamic.o" : "crtbegin.o";
          P = ToolChain.GetFilePath(crtbegin);
        }
        CmdArgs.push_back(Args.MakeArgString(P));
  	  }
  
      // Add crtfastmath.o if available and fast math is enabled.
      ToolChain.AddFastMathRuntimeIfAvailable(Args, CmdArgs);
    }
  
    Args.AddAllArgs(CmdArgs, options::OPT_L);
    Args.AddAllArgs(CmdArgs, options::OPT_u);
  
    ToolChain.AddFilePathLibArgs(Args, CmdArgs);
  
    if (D.isUsingLTO()) {
      assert(!Inputs.empty() && "Must have at least one input.");
      AddGoldPlugin(ToolChain, Args, CmdArgs, Output, Inputs[0],
                    D.getLTOMode() == LTOK_Thin);
    }
  
    if (Args.hasArg(options::OPT_Z_Xlinker__no_demangle))
      CmdArgs.push_back("--no-demangle");
  
    bool NeedsSanitizerDeps = addSanitizerRuntimes(ToolChain, Args, CmdArgs);
    bool NeedsXRayDeps = addXRayRuntime(ToolChain, Args, CmdArgs);
    AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs, JA);
    // The profile runtime also needs access to system libraries.
    getToolChain().addProfileRTLibs(Args, CmdArgs);
  
    if (D.CCCIsCXX() &&
        !Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
      if (ToolChain.ShouldLinkCXXStdlib(Args)) {
        bool OnlyLibstdcxxStatic = Args.hasArg(options::OPT_static_libstdcxx) &&
                                   !Args.hasArg(options::OPT_static);
        if (OnlyLibstdcxxStatic)
          CmdArgs.push_back("-Bstatic");
        ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
        if (OnlyLibstdcxxStatic)
          CmdArgs.push_back("-Bdynamic");
      }
      CmdArgs.push_back("-lm");
    }
    // Silence warnings when linking C code with a C++ '-stdlib' argument.
    Args.ClaimAllArgs(options::OPT_stdlib_EQ);
  
    if (!Args.hasArg(options::OPT_nostdlib)) {
      if (!Args.hasArg(options::OPT_nodefaultlibs)) {
        if (Args.hasArg(options::OPT_static) || IsStaticPIE)
          CmdArgs.push_back("--start-group");
  
        if (NeedsSanitizerDeps)
          linkSanitizerRuntimeDeps(ToolChain, CmdArgs);
  
        if (NeedsXRayDeps)
          linkXRayRuntimeDeps(ToolChain, CmdArgs);
  
        bool WantPthread = Args.hasArg(options::OPT_pthread) ||
                           Args.hasArg(options::OPT_pthreads);
  
        // FIXME: Only pass GompNeedsRT = true for platforms with libgomp that
        // require librt. Most modern Linux platforms do, but some may not.
        if (addOpenMPRuntime(CmdArgs, ToolChain, Args,
                             JA.isHostOffloading(Action::OFK_OpenMP),
                             /* GompNeedsRT= */ true))
          // OpenMP runtimes implies pthreads when using the GNU toolchain.
          // FIXME: Does this really make sense for all GNU toolchains?
          WantPthread = true;
  
        AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
  
        if (WantPthread && !isAndroid)
          CmdArgs.push_back("-lpthread");
  
        if (Args.hasArg(options::OPT_fsplit_stack))
          CmdArgs.push_back("--wrap=pthread_create");
  
        if (!Args.hasArg(options::OPT_nolibc))
          CmdArgs.push_back("-lc");
  
        // Add IAMCU specific libs, if needed.
        if (IsIAMCU)
          CmdArgs.push_back("-lgloss");
  
        if (Args.hasArg(options::OPT_static) || IsStaticPIE)
          CmdArgs.push_back("--end-group");
        else
          AddRunTimeLibs(ToolChain, D, CmdArgs, Args);
  
        // Add IAMCU specific libs (outside the group), if needed.
        if (IsIAMCU) {
          CmdArgs.push_back("--as-needed");
          CmdArgs.push_back("-lsoftfp");
          CmdArgs.push_back("--no-as-needed");
        }
      }
  
      if (!Args.hasArg(options::OPT_nostartfiles) && !IsIAMCU) {
        if (HasCRTBeginEndFiles) {
          std::string P;
          if (ToolChain.GetRuntimeLibType(Args) == ToolChain::RLT_CompilerRT &&
              !isAndroid) {
            std::string crtend = ToolChain.getCompilerRT(Args, "crtend",
                                                         ToolChain::FT_Object);
            if (ToolChain.getVFS().exists(crtend))
              P = crtend;
          }
          if (P.empty()) {
            const char *crtend;
            if (Args.hasArg(options::OPT_shared))
              crtend = isAndroid ? "crtend_so.o" : "crtendS.o";
            else if (IsPIE || IsStaticPIE)
              crtend = isAndroid ? "crtend_android.o" : "crtendS.o";
            else
              crtend = isAndroid ? "crtend_android.o" : "crtend.o";
            P = ToolChain.GetFilePath(crtend);
          }
          CmdArgs.push_back(Args.MakeArgString(P));
        }
        if (!isAndroid)
          CmdArgs.push_back(Args.MakeArgString(ToolChain.GetFilePath("crtn.o")));
      }
    }
  
    // Add OpenMP offloading linker script args if required.
    AddOpenMPLinkerScript(getToolChain(), C, Output, Inputs, Args, CmdArgs, JA);
  
    // Add HIP offloading linker script args if required.
    AddHIPLinkerScript(getToolChain(), C, Output, Inputs, Args, CmdArgs, JA,
                       *this);
  
    const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath());
    C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
  }
  
  void tools::gnutools::Assembler::ConstructJob(Compilation &C,
                                                const JobAction &JA,
                                                const InputInfo &Output,
                                                const InputInfoList &Inputs,
                                                const ArgList &Args,
                                                const char *LinkingOutput) const {
    const auto &D = getToolChain().getDriver();
  
    claimNoWarnArgs(Args);
  
    ArgStringList CmdArgs;
  
    llvm::Reloc::Model RelocationModel;
    unsigned PICLevel;
    bool IsPIE;
    std::tie(RelocationModel, PICLevel, IsPIE) =
        ParsePICArgs(getToolChain(), Args);
  
    if (const Arg *A = Args.getLastArg(options::OPT_gz, options::OPT_gz_EQ)) {
      if (A->getOption().getID() == options::OPT_gz) {
        CmdArgs.push_back("--compress-debug-sections");
      } else {
        StringRef Value = A->getValue();
        if (Value == "none" || Value == "zlib" || Value == "zlib-gnu") {
          CmdArgs.push_back(
              Args.MakeArgString("--compress-debug-sections=" + Twine(Value)));
        } else {
          D.Diag(diag::err_drv_unsupported_option_argument)
              << A->getOption().getName() << Value;
        }
      }
    }
  
    if (getToolChain().isNoExecStackDefault()) {
        CmdArgs.push_back("--noexecstack");
    }
  
    switch (getToolChain().getArch()) {
    default:
      break;
    // Add --32/--64 to make sure we get the format we want.
    // This is incomplete
    case llvm::Triple::x86:
      CmdArgs.push_back("--32");
      break;
    case llvm::Triple::x86_64:
      if (getToolChain().getTriple().getEnvironment() == llvm::Triple::GNUX32)
        CmdArgs.push_back("--x32");
      else
        CmdArgs.push_back("--64");
      break;
    case llvm::Triple::ppc: {
      CmdArgs.push_back("-a32");
      CmdArgs.push_back("-mppc");
      CmdArgs.push_back(
        ppc::getPPCAsmModeForCPU(getCPUName(Args, getToolChain().getTriple())));
      break;
    }
    case llvm::Triple::ppc64: {
      CmdArgs.push_back("-a64");
      CmdArgs.push_back("-mppc64");
      CmdArgs.push_back(
        ppc::getPPCAsmModeForCPU(getCPUName(Args, getToolChain().getTriple())));
      break;
    }
    case llvm::Triple::ppc64le: {
      CmdArgs.push_back("-a64");
      CmdArgs.push_back("-mppc64");
      CmdArgs.push_back("-mlittle-endian");
      CmdArgs.push_back(
        ppc::getPPCAsmModeForCPU(getCPUName(Args, getToolChain().getTriple())));
      break;
    }
    case llvm::Triple::riscv32:
    case llvm::Triple::riscv64: {
      StringRef ABIName = riscv::getRISCVABI(Args, getToolChain().getTriple());
      CmdArgs.push_back("-mabi");
      CmdArgs.push_back(ABIName.data());
      if (const Arg *A = Args.getLastArg(options::OPT_march_EQ)) {
        StringRef MArch = A->getValue();
        CmdArgs.push_back("-march");
        CmdArgs.push_back(MArch.data());
      }
      break;
    }
    case llvm::Triple::sparc:
    case llvm::Triple::sparcel: {
      CmdArgs.push_back("-32");
      std::string CPU = getCPUName(Args, getToolChain().getTriple());
      CmdArgs.push_back(
          sparc::getSparcAsmModeForCPU(CPU, getToolChain().getTriple()));
      AddAssemblerKPIC(getToolChain(), Args, CmdArgs);
      break;
    }
    case llvm::Triple::sparcv9: {
      CmdArgs.push_back("-64");
      std::string CPU = getCPUName(Args, getToolChain().getTriple());
      CmdArgs.push_back(
          sparc::getSparcAsmModeForCPU(CPU, getToolChain().getTriple()));
      AddAssemblerKPIC(getToolChain(), Args, CmdArgs);
      break;
    }
    case llvm::Triple::arm:
    case llvm::Triple::armeb:
    case llvm::Triple::thumb:
    case llvm::Triple::thumbeb: {
      const llvm::Triple &Triple2 = getToolChain().getTriple();
      CmdArgs.push_back(isArmBigEndian(Triple2, Args) ? "-EB" : "-EL");
      switch (Triple2.getSubArch()) {
      case llvm::Triple::ARMSubArch_v7:
        CmdArgs.push_back("-mfpu=neon");
        break;
      case llvm::Triple::ARMSubArch_v8:
        CmdArgs.push_back("-mfpu=crypto-neon-fp-armv8");
        break;
      default:
        break;
      }
  
      switch (arm::getARMFloatABI(getToolChain(), Args)) {
      case arm::FloatABI::Invalid: llvm_unreachable("must have an ABI!");
      case arm::FloatABI::Soft:
        CmdArgs.push_back(Args.MakeArgString("-mfloat-abi=soft"));
        break;
      case arm::FloatABI::SoftFP:
        CmdArgs.push_back(Args.MakeArgString("-mfloat-abi=softfp"));
        break;
      case arm::FloatABI::Hard:
        CmdArgs.push_back(Args.MakeArgString("-mfloat-abi=hard"));
        break;
      }
  
      Args.AddLastArg(CmdArgs, options::OPT_march_EQ);
      normalizeCPUNamesForAssembler(Args, CmdArgs);
  
      Args.AddLastArg(CmdArgs, options::OPT_mfpu_EQ);
      break;
    }
    case llvm::Triple::aarch64:
    case llvm::Triple::aarch64_be: {
      CmdArgs.push_back(
          getToolChain().getArch() == llvm::Triple::aarch64_be ? "-EB" : "-EL");
      Args.AddLastArg(CmdArgs, options::OPT_march_EQ);
      normalizeCPUNamesForAssembler(Args, CmdArgs);
  
      break;
    }
    case llvm::Triple::mips:
    case llvm::Triple::mipsel:
    case llvm::Triple::mips64:
    case llvm::Triple::mips64el: {
      StringRef CPUName;
      StringRef ABIName;
      mips::getMipsCPUAndABI(Args, getToolChain().getTriple(), CPUName, ABIName);
      ABIName = mips::getGnuCompatibleMipsABIName(ABIName);
  
      CmdArgs.push_back("-march");
      CmdArgs.push_back(CPUName.data());
  
      CmdArgs.push_back("-mabi");
      CmdArgs.push_back(ABIName.data());
  
      // -mno-shared should be emitted unless -fpic, -fpie, -fPIC, -fPIE,
      // or -mshared (not implemented) is in effect.
      if (RelocationModel == llvm::Reloc::Static)
        CmdArgs.push_back("-mno-shared");
  
      // LLVM doesn't support -mplt yet and acts as if it is always given.
      // However, -mplt has no effect with the N64 ABI.
      if (ABIName != "64" && !Args.hasArg(options::OPT_mno_abicalls))
        CmdArgs.push_back("-call_nonpic");
  
      if (getToolChain().getTriple().isLittleEndian())
        CmdArgs.push_back("-EL");
      else
        CmdArgs.push_back("-EB");
  
      if (Arg *A = Args.getLastArg(options::OPT_mnan_EQ)) {
        if (StringRef(A->getValue()) == "2008")
          CmdArgs.push_back(Args.MakeArgString("-mnan=2008"));
      }
  
      // Add the last -mfp32/-mfpxx/-mfp64 or -mfpxx if it is enabled by default.
      if (Arg *A = Args.getLastArg(options::OPT_mfp32, options::OPT_mfpxx,
                                   options::OPT_mfp64)) {
        A->claim();
        A->render(Args, CmdArgs);
      } else if (mips::shouldUseFPXX(
                     Args, getToolChain().getTriple(), CPUName, ABIName,
                     mips::getMipsFloatABI(getToolChain().getDriver(), Args)))
        CmdArgs.push_back("-mfpxx");
  
      // Pass on -mmips16 or -mno-mips16. However, the assembler equivalent of
      // -mno-mips16 is actually -no-mips16.
      if (Arg *A =
              Args.getLastArg(options::OPT_mips16, options::OPT_mno_mips16)) {
        if (A->getOption().matches(options::OPT_mips16)) {
          A->claim();
          A->render(Args, CmdArgs);
        } else {
          A->claim();
          CmdArgs.push_back("-no-mips16");
        }
      }
  
      Args.AddLastArg(CmdArgs, options::OPT_mmicromips,
                      options::OPT_mno_micromips);
      Args.AddLastArg(CmdArgs, options::OPT_mdsp, options::OPT_mno_dsp);
      Args.AddLastArg(CmdArgs, options::OPT_mdspr2, options::OPT_mno_dspr2);
  
      if (Arg *A = Args.getLastArg(options::OPT_mmsa, options::OPT_mno_msa)) {
        // Do not use AddLastArg because not all versions of MIPS assembler
        // support -mmsa / -mno-msa options.
        if (A->getOption().matches(options::OPT_mmsa))
          CmdArgs.push_back(Args.MakeArgString("-mmsa"));
      }
  
      Args.AddLastArg(CmdArgs, options::OPT_mhard_float,
                      options::OPT_msoft_float);
  
      Args.AddLastArg(CmdArgs, options::OPT_mdouble_float,
                      options::OPT_msingle_float);
  
      Args.AddLastArg(CmdArgs, options::OPT_modd_spreg,
                      options::OPT_mno_odd_spreg);
  
      AddAssemblerKPIC(getToolChain(), Args, CmdArgs);
      break;
    }
    case llvm::Triple::systemz: {
      // Always pass an -march option, since our default of z10 is later
      // than the GNU assembler's default.
      StringRef CPUName = systemz::getSystemZTargetCPU(Args);
      CmdArgs.push_back(Args.MakeArgString("-march=" + CPUName));
      break;
    }
    }
  
    Args.AddAllArgs(CmdArgs, options::OPT_I);
    Args.AddAllArgValues(CmdArgs, options::OPT_Wa_COMMA, options::OPT_Xassembler);
  
    CmdArgs.push_back("-o");
    CmdArgs.push_back(Output.getFilename());
  
    for (const auto &II : Inputs)
      CmdArgs.push_back(II.getFilename());
  
    const char *Exec = Args.MakeArgString(getToolChain().GetProgramPath("as"));
    C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
  
    // Handle the debug info splitting at object creation time if we're
    // creating an object.
    // TODO: Currently only works on linux with newer objcopy.
    if (Args.hasArg(options::OPT_gsplit_dwarf) &&
        getToolChain().getTriple().isOSLinux())
      SplitDebugInfo(getToolChain(), C, *this, JA, Args, Output,
                     SplitDebugName(Args, Inputs[0], Output));
  }
  
  namespace {
  // Filter to remove Multilibs that don't exist as a suffix to Path
  class FilterNonExistent {
    StringRef Base, File;
    llvm::vfs::FileSystem &VFS;
  
  public:
    FilterNonExistent(StringRef Base, StringRef File, llvm::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 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"));
  }
  
  static bool isArmOrThumbArch(llvm::Triple::ArchType Arch) {
    return Arch == llvm::Triple::arm || Arch == llvm::Triple::thumb;
  }
  
  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);
  }
  
  static bool isRISCV(llvm::Triple::ArchType Arch) {
    return Arch == llvm::Triple::riscv32 || Arch == llvm::Triple::riscv64;
  }
  
  static bool isMSP430(llvm::Triple::ArchType Arch) {
    return Arch == llvm::Triple::msp430;
  }
  
  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(llvm::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;
  }
  
  bool clang::driver::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(TargetTriple.isMIPS32(), "m32", Flags);
    addMultilibFlag(TargetTriple.isMIPS64(), "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.isGNUEnvironment())
      return findMipsMtiMultilibs(Flags, NonExistent, Result);
  
    if (TargetTriple.getVendor() == llvm::Triple::ImaginationTechnologies &&
        TargetTriple.getOS() == llvm::Triple::Linux &&
        TargetTriple.isGNUEnvironment())
      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("+march=armv7-a")
                                 .flag("-mthumb");
    Multilib ThumbMultilib = makeMultilib("/thumb")
                                 .flag("-march=armv7-a")
                                 .flag("+mthumb");
    Multilib ArmV7ThumbMultilib = makeMultilib("/armv7-a/thumb")
                                 .flag("+march=armv7-a")
                                 .flag("+mthumb");
    Multilib DefaultMultilib = makeMultilib("")
                                 .flag("-march=armv7-a")
                                 .flag("-mthumb");
    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::ISAKind::THUMB);
    bool IsArmV7Mode = (IsArmArch || IsThumbArch) &&
        (llvm::ARM::parseArchVersion(Arch) == 7 ||
         (IsArmArch && Arch == "" && IsV7SubArch));
    addMultilibFlag(IsArmV7Mode, "march=armv7-a", Flags);
    addMultilibFlag(IsThumbMode, "mthumb", Flags);
  
    if (AndroidArmMultilibs.select(Flags, Result.SelectedMultilib))
      Result.Multilibs = AndroidArmMultilibs;
  }
  
  static bool findMSP430Multilibs(const Driver &D,
                                  const llvm::Triple &TargetTriple,
                                  StringRef Path, const ArgList &Args,
                                  DetectedMultilibs &Result) {
    FilterNonExistent NonExistent(Path, "/crtbegin.o", D.getVFS());
    Multilib MSP430Multilib = makeMultilib("/430");
    // FIXME: when clang starts to support msp430x ISA additional logic
    // to select between multilib must be implemented
    // Multilib MSP430xMultilib = makeMultilib("/large");
  
    Result.Multilibs.push_back(MSP430Multilib);
    Result.Multilibs.FilterOut(NonExistent);
  
    Multilib::flags_list Flags;
    if (Result.Multilibs.select(Flags, Result.SelectedMultilib))
      return true;
  
    return false;
  }
  
  static void findRISCVMultilibs(const Driver &D,
                                 const llvm::Triple &TargetTriple, StringRef Path,
                                 const ArgList &Args, DetectedMultilibs &Result) {
  
    FilterNonExistent NonExistent(Path, "/crtbegin.o", D.getVFS());
    Multilib Ilp32 = makeMultilib("lib32/ilp32").flag("+m32").flag("+mabi=ilp32");
    Multilib Ilp32f =
        makeMultilib("lib32/ilp32f").flag("+m32").flag("+mabi=ilp32f");
    Multilib Ilp32d =
        makeMultilib("lib32/ilp32d").flag("+m32").flag("+mabi=ilp32d");
    Multilib Lp64 = makeMultilib("lib64/lp64").flag("+m64").flag("+mabi=lp64");
    Multilib Lp64f = makeMultilib("lib64/lp64f").flag("+m64").flag("+mabi=lp64f");
    Multilib Lp64d = makeMultilib("lib64/lp64d").flag("+m64").flag("+mabi=lp64d");
    MultilibSet RISCVMultilibs =
        MultilibSet()
            .Either({Ilp32, Ilp32f, Ilp32d, Lp64, Lp64f, Lp64d})
            .FilterOut(NonExistent);
  
    Multilib::flags_list Flags;
    bool IsRV64 = TargetTriple.getArch() == llvm::Triple::riscv64;
    StringRef ABIName = tools::riscv::getRISCVABI(Args, TargetTriple);
  
    addMultilibFlag(!IsRV64, "m32", Flags);
    addMultilibFlag(IsRV64, "m64", Flags);
    addMultilibFlag(ABIName == "ilp32", "mabi=ilp32", Flags);
    addMultilibFlag(ABIName == "ilp32f", "mabi=ilp32f", Flags);
    addMultilibFlag(ABIName == "ilp32d", "mabi=ilp32d", Flags);
    addMultilibFlag(ABIName == "lp64", "mabi=lp64", Flags);
    addMultilibFlag(ABIName == "lp64f", "mabi=lp64f", Flags);
    addMultilibFlag(ABIName == "lp64d", "mabi=lp64d", Flags);
  
    if (RISCVMultilibs.select(Flags, Result.SelectedMultilib))
      Result.Multilibs = RISCVMultilibs;
  }
  
  static bool findBiarchMultilibs(const Driver &D,
                                  const llvm::Triple &TargetTriple,
                                  StringRef Path, const ArgList &Args,
                                  bool NeedsBiarchSuffix,
                                  DetectedMultilibs &Result) {
    Multilib Default;
  
    // 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.
  
    StringRef Suff64 = "/64";
    // Solaris uses platform-specific suffixes instead of /64.
    if (TargetTriple.getOS() == llvm::Triple::Solaris) {
      switch (TargetTriple.getArch()) {
      case llvm::Triple::x86:
      case llvm::Triple::x86_64:
        Suff64 = "/amd64";
        break;
      case llvm::Triple::sparc:
      case llvm::Triple::sparcv9:
        Suff64 = "/sparcv9";
        break;
      default:
        break;
      }
    }
  
    Multilib Alt64 = Multilib()
                         .gccSuffix(Suff64)
                         .includeSuffix(Suff64)
                         .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;
  }
  
  /// Generic_GCC - A tool chain using the 'gcc' command to perform
  /// all subcommands; this relies on gcc translating the majority of
  /// command line options.
  
  /// 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;
  }
  
  /// Parse a GCCVersion object out of a string of text.
  ///
  /// This is the primary means of forming GCCVersion objects.
  /*static*/
  Generic_GCC::GCCVersion Generic_GCC::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;
    StringRef MinorStr = Second.first;
    if (Second.second.empty()) {
      if (size_t EndNumber = MinorStr.find_first_not_of("0123456789")) {
        GoodVersion.PatchSuffix = MinorStr.substr(EndNumber);
        MinorStr = MinorStr.slice(0, EndNumber);
      }
    }
    if (MinorStr.getAsInteger(10, GoodVersion.Minor) || GoodVersion.Minor < 0)
      return BadVersion;
    GoodVersion.MinorStr = MinorStr.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-patched
    //   4.4.0
    //   4.4.x
    //   4.4.2-rc4
    //   4.4.x-patched
    // And retains any patch number it finds.
    StringRef PatchText = Second.second;
    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;
  }
  
  static llvm::StringRef getGCCToolchainDir(const ArgList &Args,
                                            llvm::StringRef SysRoot) {
    const Arg *A = Args.getLastArg(clang::driver::options::OPT_gcc_toolchain);
    if (A)
      return A->getValue();
  
    // If we have a SysRoot, ignore GCC_INSTALL_PREFIX.
    // GCC_INSTALL_PREFIX specifies the gcc installation for the default
    // sysroot and is likely not valid with a different sysroot.
    if (!SysRoot.empty())
      return "";
  
    return GCC_INSTALL_PREFIX;
  }
  
  /// 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, D.SysRoot);
    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);
        AddDefaultGCCPrefixes(TargetTriple, Prefixes, D.SysRoot);
      }
  
      // Then look for gcc installed alongside clang.
      Prefixes.push_back(D.InstalledDir + "/..");
  
      // Next, look for prefix(es) that correspond to distribution-supplied gcc
      // installations.
      if (D.SysRoot.empty()) {
        // Typically /usr.
        AddDefaultGCCPrefixes(TargetTriple, Prefixes, D.SysRoot);
      }
    }
  
    // 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") {
      SmallVector<StringRef, 16> GentooTestTriples;
      // Try to match an exact triple as target triple first.
      // e.g. crossdev -S x86_64-gentoo-linux-gnu will install gcc libs for
      // x86_64-gentoo-linux-gnu. But "clang -target x86_64-gentoo-linux-gnu"
      // may pick the libraries for x86_64-pc-linux-gnu even when exact matching
      // triple x86_64-gentoo-linux-gnu is present.
      GentooTestTriples.push_back(TargetTriple.str());
      // Check rest of triples.
      GentooTestTriples.append(ExtraTripleAliases.begin(),
                               ExtraTripleAliases.end());
      GentooTestTriples.append(CandidateTripleAliases.begin(),
                               CandidateTripleAliases.end());
      if (ScanGentooConfigs(TargetTriple, Args, GentooTestTriples,
                            CandidateBiarchTripleAliases))
        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;
        // Try to match the exact target triple first.
        ScanLibDirForGCCTriple(TargetTriple, Args, LibDir, TargetTriple.str());
        // Try rest of possible triples.
        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;
  }
  
  void Generic_GCC::GCCInstallationDetector::AddDefaultGCCPrefixes(
      const llvm::Triple &TargetTriple, SmallVectorImpl<std::string> &Prefixes,
      StringRef SysRoot) {
    if (TargetTriple.getOS() == llvm::Triple::Solaris) {
      // Solaris is a special case.
      // The GCC installation is under
      //   /usr/gcc/<major>.<minor>/lib/gcc/<triple>/<major>.<minor>.<patch>/
      // so we need to find those /usr/gcc/*/lib/gcc libdirs and go with
      // /usr/gcc/<version> as a prefix.
  
      std::string PrefixDir = SysRoot.str() + "/usr/gcc";
      std::error_code EC;
      for (llvm::vfs::directory_iterator LI = D.getVFS().dir_begin(PrefixDir, EC),
                                         LE;
           !EC && LI != LE; LI = LI.increment(EC)) {
        StringRef VersionText = llvm::sys::path::filename(LI->path());
        GCCVersion CandidateVersion = GCCVersion::Parse(VersionText);
  
        // Filter out obviously bad entries.
        if (CandidateVersion.Major == -1 || CandidateVersion.isOlderThan(4, 1, 1))
          continue;
  
        std::string CandidatePrefix = PrefixDir + "/" + VersionText.str();
        std::string CandidateLibPath = CandidatePrefix + "/lib/gcc";
        if (!D.getVFS().exists(CandidateLibPath))
          continue;
  
        Prefixes.push_back(CandidatePrefix);
      }
      return;
    }
  
    // Non-Solaris is much simpler - most systems just go with "/usr".
    if (SysRoot.empty() && TargetTriple.getOS() == llvm::Triple::Linux) {
      // Yet, still look for RHEL devtoolsets.
      Prefixes.push_back("/opt/rh/devtoolset-8/root/usr");
      Prefixes.push_back("/opt/rh/devtoolset-7/root/usr");
      Prefixes.push_back("/opt/rh/devtoolset-6/root/usr");
      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(SysRoot.str() + "/usr");
  }
  
  /*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-redhat-linux",
        "aarch64-suse-linux", "aarch64-linux-android"};
    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",
                                               "armv6hl-suse-linux-gnueabi",
                                               "armv7hl-suse-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 AVRLibDirs[] = {"/lib"};
    static const char *const AVRTriples[] = {"avr"};
  
    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-unknown-linux",
        "x86_64-amazon-linux",    "x86_64-linux-android"};
    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", "i586-linux-gnu",
        "i686-linux-android",   "i386-gnu",              "i486-gnu",
        "i586-gnu",             "i686-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", "mipsisa32r6-linux-gnu"};
    static const char *const MIPSELLibDirs[] = {"/lib"};
    static const char *const MIPSELTriples[] = {
        "mipsel-linux-gnu", "mips-img-linux-gnu", "mipsisa32r6el-linux-gnu",
        "mipsel-linux-android"};
  
    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",
        "mipsisa64r6-linux-gnu", "mipsisa64r6-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",
        "mipsisa64r6el-linux-gnu", "mipsisa64r6el-linux-gnuabi64",
        "mips64el-linux-android"};
  
    static const char *const MIPSN32LibDirs[] = {"/lib32"};
    static const char *const MIPSN32Triples[] = {"mips64-linux-gnuabin32",
                                                 "mipsisa64r6-linux-gnuabin32"};
    static const char *const MIPSN32ELLibDirs[] = {"/lib32"};
    static const char *const MIPSN32ELTriples[] = {
        "mips64el-linux-gnuabin32", "mipsisa64r6el-linux-gnuabin32"};
  
    static const char *const MSP430LibDirs[] = {"/lib"};
    static const char *const MSP430Triples[] = {"msp430-elf"};
  
    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 RISCV32LibDirs[] = {"/lib32", "/lib"};
    static const char *const RISCV32Triples[] = {"riscv32-unknown-linux-gnu",
                                                 "riscv32-linux-gnu",
                                                 "riscv32-unknown-elf"};
    static const char *const RISCV64LibDirs[] = {"/lib64", "/lib"};
    static const char *const RISCV64Triples[] = {"riscv64-unknown-linux-gnu",
                                                 "riscv64-linux-gnu",
                                                 "riscv64-unknown-elf"};
  
    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"};
  
  
    using std::begin;
    using std::end;
  
    if (TargetTriple.getOS() == llvm::Triple::Solaris) {
      static const char *const SolarisLibDirs[] = {"/lib"};
      static const char *const SolarisSparcV8Triples[] = {
          "sparc-sun-solaris2.11", "sparc-sun-solaris2.12"};
      static const char *const SolarisSparcV9Triples[] = {
          "sparcv9-sun-solaris2.11", "sparcv9-sun-solaris2.12"};
      static const char *const SolarisX86Triples[] = {"i386-pc-solaris2.11",
                                                      "i386-pc-solaris2.12"};
      static const char *const SolarisX86_64Triples[] = {"x86_64-pc-solaris2.11",
                                                         "x86_64-pc-solaris2.12"};
      LibDirs.append(begin(SolarisLibDirs), end(SolarisLibDirs));
      BiarchLibDirs.append(begin(SolarisLibDirs), end(SolarisLibDirs));
      switch (TargetTriple.getArch()) {
      case llvm::Triple::x86:
        TripleAliases.append(begin(SolarisX86Triples), end(SolarisX86Triples));
        BiarchTripleAliases.append(begin(SolarisX86_64Triples),
                                   end(SolarisX86_64Triples));
        break;
      case llvm::Triple::x86_64:
        TripleAliases.append(begin(SolarisX86_64Triples),
                             end(SolarisX86_64Triples));
        BiarchTripleAliases.append(begin(SolarisX86Triples),
                                   end(SolarisX86Triples));
        break;
      case llvm::Triple::sparc:
        TripleAliases.append(begin(SolarisSparcV8Triples),
                             end(SolarisSparcV8Triples));
        BiarchTripleAliases.append(begin(SolarisSparcV9Triples),
                                   end(SolarisSparcV9Triples));
        break;
      case llvm::Triple::sparcv9:
        TripleAliases.append(begin(SolarisSparcV9Triples),
                             end(SolarisSparcV9Triples));
        BiarchTripleAliases.append(begin(SolarisSparcV8Triples),
                                   end(SolarisSparcV8Triples));
        break;
      default:
        break;
      }
      return;
    }
  
    // Android targets should not use GNU/Linux tools or libraries.
    if (TargetTriple.isAndroid()) {
      static const char *const AArch64AndroidTriples[] = {
          "aarch64-linux-android"};
      static const char *const ARMAndroidTriples[] = {"arm-linux-androideabi"};
      static const char *const MIPSELAndroidTriples[] = {"mipsel-linux-android"};
      static const char *const MIPS64ELAndroidTriples[] = {
          "mips64el-linux-android"};
      static const char *const X86AndroidTriples[] = {"i686-linux-android"};
      static const char *const X86_64AndroidTriples[] = {"x86_64-linux-android"};
  
      switch (TargetTriple.getArch()) {
      case llvm::Triple::aarch64:
        LibDirs.append(begin(AArch64LibDirs), end(AArch64LibDirs));
        TripleAliases.append(begin(AArch64AndroidTriples),
                             end(AArch64AndroidTriples));
        break;
      case llvm::Triple::arm:
      case llvm::Triple::thumb:
        LibDirs.append(begin(ARMLibDirs), end(ARMLibDirs));
        TripleAliases.append(begin(ARMAndroidTriples), end(ARMAndroidTriples));
        break;
      case llvm::Triple::mipsel:
        LibDirs.append(begin(MIPSELLibDirs), end(MIPSELLibDirs));
        TripleAliases.append(begin(MIPSELAndroidTriples),
                             end(MIPSELAndroidTriples));
        BiarchLibDirs.append(begin(MIPS64ELLibDirs), end(MIPS64ELLibDirs));
        BiarchTripleAliases.append(begin(MIPS64ELAndroidTriples),
                                   end(MIPS64ELAndroidTriples));
        break;
      case llvm::Triple::mips64el:
        LibDirs.append(begin(MIPS64ELLibDirs), end(MIPS64ELLibDirs));
        TripleAliases.append(begin(MIPS64ELAndroidTriples),
                             end(MIPS64ELAndroidTriples));
        BiarchLibDirs.append(begin(MIPSELLibDirs), end(MIPSELLibDirs));
        BiarchTripleAliases.append(begin(MIPSELAndroidTriples),
                                   end(MIPSELAndroidTriples));
        break;
      case llvm::Triple::x86_64:
        LibDirs.append(begin(X86_64LibDirs), end(X86_64LibDirs));
        TripleAliases.append(begin(X86_64AndroidTriples),
                             end(X86_64AndroidTriples));
        BiarchLibDirs.append(begin(X86LibDirs), end(X86LibDirs));
        BiarchTripleAliases.append(begin(X86AndroidTriples),
                                   end(X86AndroidTriples));
        break;
      case llvm::Triple::x86:
        LibDirs.append(begin(X86LibDirs), end(X86LibDirs));
        TripleAliases.append(begin(X86AndroidTriples), end(X86AndroidTriples));
        BiarchLibDirs.append(begin(X86_64LibDirs), end(X86_64LibDirs));
        BiarchTripleAliases.append(begin(X86_64AndroidTriples),
                                   end(X86_64AndroidTriples));
        break;
      default:
        break;
      }
  
      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::avr:
      LibDirs.append(begin(AVRLibDirs), end(AVRLibDirs));
      TripleAliases.append(begin(AVRTriples), end(AVRTriples));
      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));
      BiarchLibDirs.append(begin(MIPSN32LibDirs), end(MIPSN32LibDirs));
      BiarchTripleAliases.append(begin(MIPSN32Triples), end(MIPSN32Triples));
      break;
    case llvm::Triple::mipsel:
      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));
      BiarchLibDirs.append(begin(MIPSN32ELLibDirs), end(MIPSN32ELLibDirs));
      BiarchTripleAliases.append(begin(MIPSN32ELTriples), end(MIPSN32ELTriples));
      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));
      BiarchLibDirs.append(begin(MIPSN32LibDirs), end(MIPSN32LibDirs));
      BiarchTripleAliases.append(begin(MIPSN32Triples), end(MIPSN32Triples));
      break;
    case llvm::Triple::mips64el:
      LibDirs.append(begin(MIPS64ELLibDirs), end(MIPS64ELLibDirs));
      TripleAliases.append(begin(MIPS64ELTriples), end(MIPS64ELTriples));
      BiarchLibDirs.append(begin(MIPSELLibDirs), end(MIPSELLibDirs));
      BiarchTripleAliases.append(begin(MIPSELTriples), end(MIPSELTriples));
      BiarchLibDirs.append(begin(MIPSN32ELLibDirs), end(MIPSN32ELLibDirs));
      BiarchTripleAliases.append(begin(MIPSN32ELTriples), end(MIPSN32ELTriples));
      BiarchTripleAliases.append(begin(MIPSTriples), end(MIPSTriples));
      break;
    case llvm::Triple::msp430:
      LibDirs.append(begin(MSP430LibDirs), end(MSP430LibDirs));
      TripleAliases.append(begin(MSP430Triples), end(MSP430Triples));
      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::riscv32:
      LibDirs.append(begin(RISCV32LibDirs), end(RISCV32LibDirs));
      TripleAliases.append(begin(RISCV32Triples), end(RISCV32Triples));
      BiarchLibDirs.append(begin(RISCV64LibDirs), end(RISCV64LibDirs));
      BiarchTripleAliases.append(begin(RISCV64Triples), end(RISCV64Triples));
      break;
    case llvm::Triple::riscv64:
      LibDirs.append(begin(RISCV64LibDirs), end(RISCV64LibDirs));
      TripleAliases.append(begin(RISCV64Triples), end(RISCV64Triples));
      BiarchLibDirs.append(begin(RISCV32LibDirs), end(RISCV32LibDirs));
      BiarchTripleAliases.append(begin(RISCV32Triples), end(RISCV32Triples));
      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());
  }
  
  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 (TargetTriple.isMIPS()) {
      if (!findMIPSMultilibs(D, TargetTriple, Path, Args, Detected))
        return false;
    } else if (isRISCV(TargetArch)) {
      findRISCVMultilibs(D, TargetTriple, Path, Args, Detected);
    } else if (isMSP430(TargetArch)) {
      findMSP430Multilibs(D, TargetTriple, Path, Args, Detected);
    } else if (TargetArch == llvm::Triple::avr) {
      // AVR has no multilibs.
    } 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();
    // Locations relative to the system lib directory where GCC's triple-specific
    // directories might reside.
    struct GCCLibSuffix {
      // Path from system lib directory to GCC triple-specific directory.
      std::string LibSuffix;
      // Path from GCC triple-specific directory back to system lib directory.
      // This is one '..' component per component in LibSuffix.
      StringRef ReversePath;
      // Whether this library suffix is relevant for the triple.
      bool Active;
    } Suffixes[] = {
        // This is the normal place.
        {"gcc/" + CandidateTriple.str(), "../..", true},
  
        // Debian puts cross-compilers in gcc-cross.
        {"gcc-cross/" + CandidateTriple.str(), "../..",
         TargetTriple.getOS() != llvm::Triple::Solaris},
  
        // The Freescale PPC SDK has the gcc libraries in
        // <sysroot>/usr/lib/<triple>/x.y.z so have a look there as well. Only do
        // this on Freescale triples, though, since some systems put a *lot* of
        // files in that location, not just GCC installation data.
        {CandidateTriple.str(), "..",
         TargetTriple.getVendor() == llvm::Triple::Freescale ||
         TargetTriple.getVendor() == llvm::Triple::OpenEmbedded},
  
        // Natively multiarch systems sometimes put the GCC triple-specific
        // directory within their multiarch lib directory, resulting in the
        // triple appearing twice.
        {CandidateTriple.str() + "/gcc/" + CandidateTriple.str(), "../../..",
         TargetTriple.getOS() != llvm::Triple::Solaris},
  
        // Deal with cases (on Ubuntu) where the system architecture could be i386
        // but the GCC target architecture could be (say) i686.
        // FIXME: It may be worthwhile to generalize this and look for a second
        // triple.
        {"i386-linux-gnu/gcc/" + CandidateTriple.str(), "../../..",
         (TargetArch == llvm::Triple::x86 &&
          TargetTriple.getOS() != llvm::Triple::Solaris)},
        {"i386-gnu/gcc/" + CandidateTriple.str(), "../../..",
         (TargetArch == llvm::Triple::x86 &&
          TargetTriple.getOS() != llvm::Triple::Solaris)}};
  
    for (auto &Suffix : Suffixes) {
      if (!Suffix.Active)
        continue;
  
      StringRef LibSuffix = Suffix.LibSuffix;
      std::error_code EC;
      for (llvm::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->path());
        GCCVersion CandidateVersion = GCCVersion::Parse(VersionText);
        if (CandidateVersion.Major != -1) // Filter obviously bad entries.
          if (!CandidateGCCInstallPaths.insert(LI->path()).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->path(),
                                 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 + "/" + LibSuffix + "/" + VersionText).str();
        GCCParentLibPath = (GCCInstallPath + "/../" + Suffix.ReversePath).str();
        IsValid = true;
      }
    }
  }
  
  bool Generic_GCC::GCCInstallationDetector::ScanGentooConfigs(
      const llvm::Triple &TargetTriple, const ArgList &Args,
      const SmallVectorImpl<StringRef> &CandidateTriples,
      const SmallVectorImpl<StringRef> &CandidateBiarchTriples) {
    for (StringRef CandidateTriple : CandidateTriples) {
      if (ScanGentooGccConfig(TargetTriple, Args, CandidateTriple))
        return true;
    }
  
    for (StringRef CandidateTriple : CandidateBiarchTriples) {
      if (ScanGentooGccConfig(TargetTriple, Args, CandidateTriple, true))
        return true;
    }
    return false;
  }
  
  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) {
        Line = Line.trim();
        // CURRENT=triple-version
        if (!Line.consume_front("CURRENT="))
          continue;
        // Process the config file pointed to by CURRENT.
        llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> ConfigFile =
            D.getVFS().getBufferForFile(D.SysRoot + "/etc/env.d/gcc/" +
                                        Line.str());
        std::pair<StringRef, StringRef> ActiveVersion = Line.rsplit('-');
        // List of paths to scan for libraries.
        SmallVector<StringRef, 4> GentooScanPaths;
        // Scan the Config file to find installed GCC libraries path.
        // Typical content of the GCC config file:
        // LDPATH="/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.x:/usr/lib/gcc/
        // (continued from previous line) x86_64-pc-linux-gnu/4.9.x/32"
        // MANPATH="/usr/share/gcc-data/x86_64-pc-linux-gnu/4.9.x/man"
        // INFOPATH="/usr/share/gcc-data/x86_64-pc-linux-gnu/4.9.x/info"
        // STDCXX_INCDIR="/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.x/include/g++-v4"
        // We are looking for the paths listed in LDPATH=... .
        if (ConfigFile) {
          SmallVector<StringRef, 2> ConfigLines;
          ConfigFile.get()->getBuffer().split(ConfigLines, "\n");
          for (StringRef ConfLine : ConfigLines) {
            ConfLine = ConfLine.trim();
            if (ConfLine.consume_front("LDPATH=")) {
              // Drop '"' from front and back if present.
              ConfLine.consume_back("\"");
              ConfLine.consume_front("\"");
              // Get all paths sperated by ':'
              ConfLine.split(GentooScanPaths, ':', -1, /*AllowEmpty*/ false);
            }
          }
        }
        // Test the path based on the version in /etc/env.d/gcc/config-{tuple}.
        std::string basePath = "/usr/lib/gcc/" + ActiveVersion.first.str() + "/"
            + ActiveVersion.second.str();
        GentooScanPaths.push_back(StringRef(basePath));
  
        // Scan all paths for GCC libraries.
        for (const auto &GentooScanPath : GentooScanPaths) {
          std::string GentooPath = D.SysRoot + std::string(GentooScanPath);
          if (D.getVFS().exists(GentooPath + "/crtbegin.o")) {
            if (!ScanGCCForMultilibs(TargetTriple, Args, GentooPath,
                                     NeedsBiarchSuffix))
              continue;
  
            Version = GCCVersion::Parse(ActiveVersion.second);
            GCCInstallPath = GentooPath;
            GCCParentLibPath = GentooPath + std::string("/../../..");
            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 clang::driver::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 ArgList &Args) 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:
      // Big endian PPC is PIC by default
      return !getTriple().isOSBinFormatMachO() && !getTriple().isMacOSX();
    case llvm::Triple::mips64:
    case llvm::Triple::mips64el:
      return true;
    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::avr:
    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::riscv32:
    case llvm::Triple::riscv64:
    case llvm::Triple::systemz:
    case llvm::Triple::mips:
    case llvm::Triple::mipsel:
    case llvm::Triple::mips64:
    case llvm::Triple::mips64el:
    case llvm::Triple::msp430:
      return true;
    case llvm::Triple::sparc:
    case llvm::Triple::sparcel:
    case llvm::Triple::sparcv9:
      if (getTriple().isOSFreeBSD() || getTriple().isOSOpenBSD() ||
          getTriple().isOSSolaris())
        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:
      addLibCxxIncludePaths(DriverArgs, CC1Args);
      break;
  
    case ToolChain::CST_Libstdcxx:
      addLibStdCxxIncludePaths(DriverArgs, CC1Args);
      break;
    }
  }
  
  void
  Generic_GCC::addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                     llvm::opt::ArgStringList &CC1Args) const {
    // FIXME: The Linux behavior would probaby be a better approach here.
    addSystemInclude(DriverArgs, CC1Args,
                     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.
  }
  
  /// 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::anchor() {}
  
  void Generic_ELF::addClangTargetOptions(const ArgList &DriverArgs,
                                          ArgStringList &CC1Args,
                                          Action::OffloadKind) const {
    const Generic_GCC::GCCVersion &V = GCCInstallation.getVersion();
    bool UseInitArrayDefault =
        getTriple().getArch() == llvm::Triple::aarch64 ||
        getTriple().getArch() == llvm::Triple::aarch64_be ||
        (getTriple().isOSFreeBSD() &&
         getTriple().getOSMajorVersion() >= 12) ||
        (getTriple().getOS() == llvm::Triple::Linux &&
         ((!GCCInstallation.isValid() || !V.isOlderThan(4, 7, 0)) ||
          getTriple().isAndroid())) ||
        getTriple().getOS() == llvm::Triple::NaCl ||
        (getTriple().getVendor() == llvm::Triple::MipsTechnologies &&
         !getTriple().hasEnvironment()) ||
        getTriple().getOS() == llvm::Triple::Solaris ||
        getTriple().getArch() == llvm::Triple::riscv32 ||
        getTriple().getArch() == llvm::Triple::riscv64;
  
    if (DriverArgs.hasFlag(options::OPT_fuse_init_array,
                           options::OPT_fno_use_init_array, UseInitArrayDefault))
      CC1Args.push_back("-fuse-init-array");
  }
  