SanitizerArgs::SanitizerArgs(const ToolChain &TC,
                             const llvm::opt::ArgList &Args) {
  SanitizerMask AllRemove = 0;  // During the loop below, the accumulated set of
                                // sanitizers disabled by the current sanitizer
                                // argument or any argument after it.
  SanitizerMask AllAddedKinds = 0;  // Mask of all sanitizers ever enabled by
                                    // -fsanitize= flags (directly or via group
                                    // expansion), some of which may be disabled
                                    // later. Used to carefully prune
                                    // unused-argument diagnostics.
  SanitizerMask DiagnosedKinds = 0;  // All Kinds we have diagnosed up to now.
                                     // Used to deduplicate diagnostics.
  SanitizerMask Kinds = 0;
  const SanitizerMask Supported = setGroupBits(TC.getSupportedSanitizers());
  ToolChain::RTTIMode RTTIMode = TC.getRTTIMode();

  const Driver &D = TC.getDriver();
  SanitizerMask TrappingKinds = parseSanitizeTrapArgs(D, Args);
  SanitizerMask InvalidTrappingKinds = TrappingKinds & NotAllowedWithTrap;

  for (ArgList::const_reverse_iterator I = Args.rbegin(), E = Args.rend();
       I != E; ++I) {
    const auto *Arg = *I;
    if (Arg->getOption().matches(options::OPT_fsanitize_EQ)) {
      Arg->claim();
      SanitizerMask Add = parseArgValues(D, Arg, true);
      AllAddedKinds |= expandSanitizerGroups(Add);

      // Avoid diagnosing any sanitizer which is disabled later.
      Add &= ~AllRemove;
      // At this point we have not expanded groups, so any unsupported
      // sanitizers in Add are those which have been explicitly enabled.
      // Diagnose them.
      if (SanitizerMask KindsToDiagnose =
              Add & InvalidTrappingKinds & ~DiagnosedKinds) {
        std::string Desc = describeSanitizeArg(*I, KindsToDiagnose);
        D.Diag(diag::err_drv_argument_not_allowed_with)
            << Desc << "-fsanitize-trap=undefined";
        DiagnosedKinds |= KindsToDiagnose;
      }
      Add &= ~InvalidTrappingKinds;
      if (SanitizerMask KindsToDiagnose = Add & ~Supported & ~DiagnosedKinds) {
        std::string Desc = describeSanitizeArg(*I, KindsToDiagnose);
        D.Diag(diag::err_drv_unsupported_opt_for_target)
            << Desc << TC.getTriple().str();
        DiagnosedKinds |= KindsToDiagnose;
      }
      Add &= Supported;

      // Test for -fno-rtti + explicit -fsanitizer=vptr before expanding groups
      // so we don't error out if -fno-rtti and -fsanitize=undefined were
      // passed.
      if (Add & Vptr &&
          (RTTIMode == ToolChain::RM_DisabledImplicitly ||
           RTTIMode == ToolChain::RM_DisabledExplicitly)) {
        if (RTTIMode == ToolChain::RM_DisabledImplicitly)
          // Warn about not having rtti enabled if the vptr sanitizer is
          // explicitly enabled
          D.Diag(diag::warn_drv_disabling_vptr_no_rtti_default);
        else {
          const llvm::opt::Arg *NoRTTIArg = TC.getRTTIArg();
          assert(NoRTTIArg &&
                 "RTTI disabled explicitly but we have no argument!");
          D.Diag(diag::err_drv_argument_not_allowed_with)
              << "-fsanitize=vptr" << NoRTTIArg->getAsString(Args);
        }

        // Take out the Vptr sanitizer from the enabled sanitizers
        AllRemove |= Vptr;
      }

      Add = expandSanitizerGroups(Add);
      // Group expansion may have enabled a sanitizer which is disabled later.
      Add &= ~AllRemove;
      // Silently discard any unsupported sanitizers implicitly enabled through
      // group expansion.
      Add &= ~InvalidTrappingKinds;
      Add &= Supported;

      Kinds |= Add;
    } else if (Arg->getOption().matches(options::OPT_fno_sanitize_EQ)) {
      Arg->claim();
      SanitizerMask Remove = parseArgValues(D, Arg, true);
      AllRemove |= expandSanitizerGroups(Remove);
    }
  }

  // Enable toolchain specific default sanitizers if not explicitly disabled.
  Kinds |= TC.getDefaultSanitizers() & ~AllRemove;

  // We disable the vptr sanitizer if it was enabled by group expansion but RTTI
  // is disabled.
  if ((Kinds & Vptr) &&
      (RTTIMode == ToolChain::RM_DisabledImplicitly ||
       RTTIMode == ToolChain::RM_DisabledExplicitly)) {
    Kinds &= ~Vptr;
  }

  // Check that LTO is enabled if we need it.
  if ((Kinds & NeedsLTO) && !D.isUsingLTO()) {
    D.Diag(diag::err_drv_argument_only_allowed_with)
        << lastArgumentForMask(D, Args, Kinds & NeedsLTO) << "-flto";
  }

  // Report error if there are non-trapping sanitizers that require
  // c++abi-specific  parts of UBSan runtime, and they are not provided by the
  // toolchain. We don't have a good way to check the latter, so we just
  // check if the toolchan supports vptr.
  if (~Supported & Vptr) {
    SanitizerMask KindsToDiagnose = Kinds & ~TrappingKinds & NeedsUbsanCxxRt;
    // The runtime library supports the Microsoft C++ ABI, but only well enough
    // for CFI. FIXME: Remove this once we support vptr on Windows.
    if (TC.getTriple().isOSWindows())
      KindsToDiagnose &= ~CFI;
    if (KindsToDiagnose) {
      SanitizerSet S;
      S.Mask = KindsToDiagnose;
      D.Diag(diag::err_drv_unsupported_opt_for_target)
          << ("-fno-sanitize-trap=" + toString(S)) << TC.getTriple().str();
      Kinds &= ~KindsToDiagnose;
    }
  }

  // Warn about incompatible groups of sanitizers.
  std::pair<SanitizerMask, SanitizerMask> IncompatibleGroups[] = {
      std::make_pair(Address, Thread), std::make_pair(Address, Memory),
      std::make_pair(Thread, Memory), std::make_pair(Leak, Thread),
      std::make_pair(Leak, Memory), std::make_pair(KernelAddress, Address),
      std::make_pair(KernelAddress, Leak),
      std::make_pair(KernelAddress, Thread),
      std::make_pair(KernelAddress, Memory),
      std::make_pair(Efficiency, Address),
      std::make_pair(Efficiency, Leak),
      std::make_pair(Efficiency, Thread),
      std::make_pair(Efficiency, Memory),
      std::make_pair(Efficiency, KernelAddress)};
  for (auto G : IncompatibleGroups) {
    SanitizerMask Group = G.first;
    if (Kinds & Group) {
      if (SanitizerMask Incompatible = Kinds & G.second) {
        D.Diag(clang::diag::err_drv_argument_not_allowed_with)
            << lastArgumentForMask(D, Args, Group)
            << lastArgumentForMask(D, Args, Incompatible);
        Kinds &= ~Incompatible;
      }
    }
  }
  // FIXME: Currently -fsanitize=leak is silently ignored in the presence of
  // -fsanitize=address. Perhaps it should print an error, or perhaps
  // -f(-no)sanitize=leak should change whether leak detection is enabled by
  // default in ASan?

  // Parse -f(no-)?sanitize-recover flags.
  SanitizerMask RecoverableKinds = RecoverableByDefault;
  SanitizerMask DiagnosedUnrecoverableKinds = 0;
  for (const auto *Arg : Args) {
    const char *DeprecatedReplacement = nullptr;
    if (Arg->getOption().matches(options::OPT_fsanitize_recover)) {
      DeprecatedReplacement =
          "-fsanitize-recover=undefined,integer' or '-fsanitize-recover=all";
      RecoverableKinds |= expandSanitizerGroups(LegacyFsanitizeRecoverMask);
      Arg->claim();
    } else if (Arg->getOption().matches(options::OPT_fno_sanitize_recover)) {
      DeprecatedReplacement = "-fno-sanitize-recover=undefined,integer' or "
                              "'-fno-sanitize-recover=all";
      RecoverableKinds &= ~expandSanitizerGroups(LegacyFsanitizeRecoverMask);
      Arg->claim();
    } else if (Arg->getOption().matches(options::OPT_fsanitize_recover_EQ)) {
      SanitizerMask Add = parseArgValues(D, Arg, true);
      // Report error if user explicitly tries to recover from unrecoverable
      // sanitizer.
      if (SanitizerMask KindsToDiagnose =
              Add & Unrecoverable & ~DiagnosedUnrecoverableKinds) {
        SanitizerSet SetToDiagnose;
        SetToDiagnose.Mask |= KindsToDiagnose;
        D.Diag(diag::err_drv_unsupported_option_argument)
            << Arg->getOption().getName() << toString(SetToDiagnose);
        DiagnosedUnrecoverableKinds |= KindsToDiagnose;
      }
      RecoverableKinds |= expandSanitizerGroups(Add);
      Arg->claim();
    } else if (Arg->getOption().matches(options::OPT_fno_sanitize_recover_EQ)) {
      RecoverableKinds &= ~expandSanitizerGroups(parseArgValues(D, Arg, true));
      Arg->claim();
    }
    if (DeprecatedReplacement) {
      D.Diag(diag::warn_drv_deprecated_arg) << Arg->getAsString(Args)
                                            << DeprecatedReplacement;
    }
  }
  RecoverableKinds &= Kinds;
  RecoverableKinds &= ~Unrecoverable;

  TrappingKinds &= Kinds;

  // Setup blacklist files.
  // Add default blacklist from resource directory.
  {
    std::string BLPath;
    if (getDefaultBlacklist(D, Kinds, BLPath) && llvm::sys::fs::exists(BLPath))
      BlacklistFiles.push_back(BLPath);
  }
  // Parse -f(no-)sanitize-blacklist options.
  for (const auto *Arg : Args) {
    if (Arg->getOption().matches(options::OPT_fsanitize_blacklist)) {
      Arg->claim();
      std::string BLPath = Arg->getValue();
      if (llvm::sys::fs::exists(BLPath)) {
        BlacklistFiles.push_back(BLPath);
        ExtraDeps.push_back(BLPath);
      } else
        D.Diag(clang::diag::err_drv_no_such_file) << BLPath;

    } else if (Arg->getOption().matches(options::OPT_fno_sanitize_blacklist)) {
      Arg->claim();
      BlacklistFiles.clear();
      ExtraDeps.clear();
    }
  }
  // Validate blacklists format.
  {
    std::string BLError;
    std::unique_ptr<llvm::SpecialCaseList> SCL(
        llvm::SpecialCaseList::create(BlacklistFiles, BLError));
    if (!SCL.get())
      D.Diag(clang::diag::err_drv_malformed_sanitizer_blacklist) << BLError;
  }

  // Parse -f[no-]sanitize-memory-track-origins[=level] options.
  if (AllAddedKinds & Memory) {
    if (Arg *A =
            Args.getLastArg(options::OPT_fsanitize_memory_track_origins_EQ,
                            options::OPT_fsanitize_memory_track_origins,
                            options::OPT_fno_sanitize_memory_track_origins)) {
      if (A->getOption().matches(options::OPT_fsanitize_memory_track_origins)) {
        MsanTrackOrigins = 2;
      } else if (A->getOption().matches(
                     options::OPT_fno_sanitize_memory_track_origins)) {
        MsanTrackOrigins = 0;
      } else {
        StringRef S = A->getValue();
        if (S.getAsInteger(0, MsanTrackOrigins) || MsanTrackOrigins < 0 ||
            MsanTrackOrigins > 2) {
          D.Diag(clang::diag::err_drv_invalid_value) << A->getAsString(Args) << S;
        }
      }
    }
    MsanUseAfterDtor =
        Args.hasArg(options::OPT_fsanitize_memory_use_after_dtor);
    NeedPIE |= !(TC.getTriple().isOSLinux() &&
                 TC.getTriple().getArch() == llvm::Triple::x86_64);
  }

  if (AllAddedKinds & CFI) {
    CfiCrossDso = Args.hasFlag(options::OPT_fsanitize_cfi_cross_dso,
                               options::OPT_fno_sanitize_cfi_cross_dso, false);
    // Without PIE, external function address may resolve to a PLT record, which
    // can not be verified by the target module.
    NeedPIE |= CfiCrossDso;
  }

  Stats = Args.hasFlag(options::OPT_fsanitize_stats,
                       options::OPT_fno_sanitize_stats, false);

  // Parse -f(no-)?sanitize-coverage flags if coverage is supported by the
  // enabled sanitizers.
  for (const auto *Arg : Args) {
    if (Arg->getOption().matches(options::OPT_fsanitize_coverage)) {
      int LegacySanitizeCoverage;
      if (Arg->getNumValues() == 1 &&
          !StringRef(Arg->getValue(0))
               .getAsInteger(0, LegacySanitizeCoverage) &&
          LegacySanitizeCoverage >= 0 && LegacySanitizeCoverage <= 4) {
        switch (LegacySanitizeCoverage) {
        case 0:
          CoverageFeatures = 0;
          Arg->claim();
          break;
        case 1:
          D.Diag(diag::warn_drv_deprecated_arg) << Arg->getAsString(Args)
                                                << "-fsanitize-coverage=func";
          CoverageFeatures = CoverageFunc;
          break;
        case 2:
          D.Diag(diag::warn_drv_deprecated_arg) << Arg->getAsString(Args)
                                                << "-fsanitize-coverage=bb";
          CoverageFeatures = CoverageBB;
          break;
        case 3:
          D.Diag(diag::warn_drv_deprecated_arg) << Arg->getAsString(Args)
                                                << "-fsanitize-coverage=edge";
          CoverageFeatures = CoverageEdge;
          break;
        case 4:
          D.Diag(diag::warn_drv_deprecated_arg)
              << Arg->getAsString(Args)
              << "-fsanitize-coverage=edge,indirect-calls";
          CoverageFeatures = CoverageEdge | CoverageIndirCall;
          break;
        }
        continue;
      }
      CoverageFeatures |= parseCoverageFeatures(D, Arg);

      // Disable coverage and not claim the flags if there is at least one
      // non-supporting sanitizer.
      if (!(AllAddedKinds & ~setGroupBits(SupportsCoverage))) {
        Arg->claim();
      } else {
        CoverageFeatures = 0;
      }
    } else if (Arg->getOption().matches(options::OPT_fno_sanitize_coverage)) {
      Arg->claim();
      CoverageFeatures &= ~parseCoverageFeatures(D, Arg);
    }
  }
  // Choose at most one coverage type: function, bb, or edge.
  if ((CoverageFeatures & CoverageFunc) && (CoverageFeatures & CoverageBB))
    D.Diag(clang::diag::err_drv_argument_not_allowed_with)
        << "-fsanitize-coverage=func"
        << "-fsanitize-coverage=bb";
  if ((CoverageFeatures & CoverageFunc) && (CoverageFeatures & CoverageEdge))
    D.Diag(clang::diag::err_drv_argument_not_allowed_with)
        << "-fsanitize-coverage=func"
        << "-fsanitize-coverage=edge";
  if ((CoverageFeatures & CoverageBB) && (CoverageFeatures & CoverageEdge))
    D.Diag(clang::diag::err_drv_argument_not_allowed_with)
        << "-fsanitize-coverage=bb"
        << "-fsanitize-coverage=edge";
  // Basic block tracing and 8-bit counters require some type of coverage
  // enabled.
  int CoverageTypes = CoverageFunc | CoverageBB | CoverageEdge;
  if ((CoverageFeatures & CoverageTraceBB) &&
      !(CoverageFeatures & CoverageTypes))
    D.Diag(clang::diag::err_drv_argument_only_allowed_with)
        << "-fsanitize-coverage=trace-bb"
        << "-fsanitize-coverage=(func|bb|edge)";
  if ((CoverageFeatures & Coverage8bitCounters) &&
      !(CoverageFeatures & CoverageTypes))
    D.Diag(clang::diag::err_drv_argument_only_allowed_with)
        << "-fsanitize-coverage=8bit-counters"
        << "-fsanitize-coverage=(func|bb|edge)";
  // trace-pc w/o func/bb/edge implies edge.
  if ((CoverageFeatures & CoverageTracePC) &&
      !(CoverageFeatures & CoverageTypes))
    CoverageFeatures |= CoverageEdge;

  if (AllAddedKinds & Address) {
    AsanSharedRuntime =
        Args.hasArg(options::OPT_shared_libasan) || TC.getTriple().isAndroid();
    NeedPIE |= TC.getTriple().isAndroid();
    if (Arg *A =
            Args.getLastArg(options::OPT_fsanitize_address_field_padding)) {
        StringRef S = A->getValue();
        // Legal values are 0 and 1, 2, but in future we may add more levels.
        if (S.getAsInteger(0, AsanFieldPadding) || AsanFieldPadding < 0 ||
            AsanFieldPadding > 2) {
          D.Diag(clang::diag::err_drv_invalid_value) << A->getAsString(Args) << S;
        }
    }

    if (Arg *WindowsDebugRTArg =
            Args.getLastArg(options::OPT__SLASH_MTd, options::OPT__SLASH_MT,
                            options::OPT__SLASH_MDd, options::OPT__SLASH_MD,
                            options::OPT__SLASH_LDd, options::OPT__SLASH_LD)) {
      switch (WindowsDebugRTArg->getOption().getID()) {
      case options::OPT__SLASH_MTd:
      case options::OPT__SLASH_MDd:
      case options::OPT__SLASH_LDd:
        D.Diag(clang::diag::err_drv_argument_not_allowed_with)
            << WindowsDebugRTArg->getAsString(Args)
            << lastArgumentForMask(D, Args, Address);
        D.Diag(clang::diag::note_drv_address_sanitizer_debug_runtime);
      }
    }
  }

  AsanUseAfterScope =
      Args.hasArg(options::OPT_fsanitize_address_use_after_scope);
  if (AsanUseAfterScope && !(AllAddedKinds & Address)) {
    D.Diag(clang::diag::err_drv_argument_only_allowed_with)
        << "-fsanitize-address-use-after-scope"
        << "-fsanitize=address";
  }

  // Parse -link-cxx-sanitizer flag.
  LinkCXXRuntimes =
      Args.hasArg(options::OPT_fsanitize_link_cxx_runtime) || D.CCCIsCXX();

  // Finally, initialize the set of available and recoverable sanitizers.
  Sanitizers.Mask |= Kinds;
  RecoverableSanitizers.Mask |= RecoverableKinds;
  TrapSanitizers.Mask |= TrappingKinds;
}