text: //===--- BackendUtil.cpp - LLVM Backend Utilities -------------------------===//
  //
  // 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 "clang/CodeGen/BackendUtil.h"
  #include "clang/Basic/CodeGenOptions.h"
  #include "clang/Basic/Diagnostic.h"
  #include "clang/Basic/LangOptions.h"
  #include "clang/Basic/TargetOptions.h"
  #include "clang/Frontend/FrontendDiagnostic.h"
  #include "clang/Frontend/Utils.h"
  #include "clang/Lex/HeaderSearchOptions.h"
  #include "llvm/ADT/SmallSet.h"
  #include "llvm/ADT/StringExtras.h"
  #include "llvm/ADT/StringSwitch.h"
  #include "llvm/ADT/Triple.h"
  #include "llvm/Analysis/AliasAnalysis.h"
  #include "llvm/Analysis/StackSafetyAnalysis.h"
  #include "llvm/Analysis/TargetLibraryInfo.h"
  #include "llvm/Analysis/TargetTransformInfo.h"
  #include "llvm/Bitcode/BitcodeReader.h"
  #include "llvm/Bitcode/BitcodeWriter.h"
  #include "llvm/Bitcode/BitcodeWriterPass.h"
  #include "llvm/CodeGen/RegAllocRegistry.h"
  #include "llvm/CodeGen/SchedulerRegistry.h"
  #include "llvm/CodeGen/TargetSubtargetInfo.h"
  #include "llvm/IR/DataLayout.h"
  #include "llvm/IR/IRPrintingPasses.h"
  #include "llvm/IR/LegacyPassManager.h"
  #include "llvm/IR/Module.h"
  #include "llvm/IR/ModuleSummaryIndex.h"
  #include "llvm/IR/PassManager.h"
  #include "llvm/IR/Verifier.h"
  #include "llvm/LTO/LTOBackend.h"
  #include "llvm/MC/MCAsmInfo.h"
  #include "llvm/MC/SubtargetFeature.h"
  #include "llvm/MC/TargetRegistry.h"
  #include "llvm/Passes/PassBuilder.h"
  #include "llvm/Passes/PassPlugin.h"
  #include "llvm/Passes/StandardInstrumentations.h"
  #include "llvm/SYCLLowerIR/LowerWGLocalMemory.h"
  #include "llvm/Support/BuryPointer.h"
  #include "llvm/Support/CommandLine.h"
  #include "llvm/Support/MemoryBuffer.h"
  #include "llvm/Support/PrettyStackTrace.h"
  #include "llvm/Support/TimeProfiler.h"
  #include "llvm/Support/Timer.h"
  #include "llvm/Support/ToolOutputFile.h"
  #include "llvm/Support/raw_ostream.h"
  #include "llvm/Target/TargetMachine.h"
  #include "llvm/Target/TargetOptions.h"
  #include "llvm/Transforms/Coroutines.h"
  #include "llvm/Transforms/Coroutines/CoroCleanup.h"
  #include "llvm/Transforms/Coroutines/CoroEarly.h"
  #include "llvm/Transforms/Coroutines/CoroElide.h"
  #include "llvm/Transforms/Coroutines/CoroSplit.h"
  #include "llvm/Transforms/IPO.h"
  #include "llvm/Transforms/IPO/AlwaysInliner.h"
  #include "llvm/Transforms/IPO/LowerTypeTests.h"
  #include "llvm/Transforms/IPO/PassManagerBuilder.h"
  #include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
  #include "llvm/Transforms/InstCombine/InstCombine.h"
  #include "llvm/Transforms/Instrumentation.h"
  #include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
  #include "llvm/Transforms/Instrumentation/AddressSanitizerOptions.h"
  #include "llvm/Transforms/Instrumentation/BoundsChecking.h"
  #include "llvm/Transforms/Instrumentation/DataFlowSanitizer.h"
  #include "llvm/Transforms/Instrumentation/GCOVProfiler.h"
  #include "llvm/Transforms/Instrumentation/HWAddressSanitizer.h"
  #include "llvm/Transforms/Instrumentation/InstrProfiling.h"
  #include "llvm/Transforms/Instrumentation/MemProfiler.h"
  #include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
  #include "llvm/Transforms/Instrumentation/SPIRITTAnnotations.h"
  #include "llvm/Transforms/Instrumentation/SanitizerCoverage.h"
  #include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
  #include "llvm/Transforms/ObjCARC.h"
  #include "llvm/Transforms/Scalar.h"
  #include "llvm/Transforms/Scalar/EarlyCSE.h"
  #include "llvm/Transforms/Scalar/GVN.h"
  #include "llvm/Transforms/Scalar/LowerMatrixIntrinsics.h"
  #include "llvm/Transforms/Utils.h"
  #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
  #include "llvm/Transforms/Utils/Debugify.h"
  #include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
  #include "llvm/Transforms/Utils/NameAnonGlobals.h"
  #include "llvm/Transforms/Utils/SymbolRewriter.h"
  #include <memory>
  using namespace clang;
  using namespace llvm;
  
  #define HANDLE_EXTENSION(Ext)                                                  \
    llvm::PassPluginLibraryInfo get##Ext##PluginInfo();
  #include "llvm/Support/Extension.def"
  
  namespace {
  
  // Default filename used for profile generation.
  static constexpr StringLiteral DefaultProfileGenName = "default_%m.profraw";
  
  class EmitAssemblyHelper {
    DiagnosticsEngine &Diags;
    const HeaderSearchOptions &HSOpts;
    const CodeGenOptions &CodeGenOpts;
    const clang::TargetOptions &TargetOpts;
    const LangOptions &LangOpts;
    Module *TheModule;
  
    Timer CodeGenerationTime;
  
    std::unique_ptr<raw_pwrite_stream> OS;
  
    TargetIRAnalysis getTargetIRAnalysis() const {
      if (TM)
        return TM->getTargetIRAnalysis();
  
      return TargetIRAnalysis();
    }
  
    void CreatePasses(legacy::PassManager &MPM, legacy::FunctionPassManager &FPM);
  
    /// Generates the TargetMachine.
    /// Leaves TM unchanged if it is unable to create the target machine.
    /// Some of our clang tests specify triples which are not built
    /// into clang. This is okay because these tests check the generated
    /// IR, and they require DataLayout which depends on the triple.
    /// In this case, we allow this method to fail and not report an error.
    /// When MustCreateTM is used, we print an error if we are unable to load
    /// the requested target.
    void CreateTargetMachine(bool MustCreateTM);
  
    /// Add passes necessary to emit assembly or LLVM IR.
    ///
    /// \return True on success.
    bool AddEmitPasses(legacy::PassManager &CodeGenPasses, BackendAction Action,
                       raw_pwrite_stream &OS, raw_pwrite_stream *DwoOS);
  
    std::unique_ptr<llvm::ToolOutputFile> openOutputFile(StringRef Path) {
      std::error_code EC;
      auto F = std::make_unique<llvm::ToolOutputFile>(Path, EC,
                                                       llvm::sys::fs::OF_None);
      if (EC) {
        Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
        F.reset();
      }
      return F;
    }
  
    void
    RunOptimizationPipeline(BackendAction Action,
                            std::unique_ptr<raw_pwrite_stream> &OS,
                            std::unique_ptr<llvm::ToolOutputFile> &ThinLinkOS);
    void RunCodegenPipeline(BackendAction Action,
                            std::unique_ptr<raw_pwrite_stream> &OS,
                            std::unique_ptr<llvm::ToolOutputFile> &DwoOS);
  
  public:
    EmitAssemblyHelper(DiagnosticsEngine &_Diags,
                       const HeaderSearchOptions &HeaderSearchOpts,
                       const CodeGenOptions &CGOpts,
                       const clang::TargetOptions &TOpts,
                       const LangOptions &LOpts, Module *M)
        : Diags(_Diags), HSOpts(HeaderSearchOpts), CodeGenOpts(CGOpts),
          TargetOpts(TOpts), LangOpts(LOpts), TheModule(M),
          CodeGenerationTime("codegen", "Code Generation Time") {}
  
    ~EmitAssemblyHelper() {
      if (CodeGenOpts.DisableFree)
        BuryPointer(std::move(TM));
    }
  
    std::unique_ptr<TargetMachine> TM;
  
    // Emit output using the legacy pass manager for the optimization pipeline.
    // This will be removed soon when using the legacy pass manager for the
    // optimization pipeline is no longer supported.
    void EmitAssemblyWithLegacyPassManager(BackendAction Action,
                                           std::unique_ptr<raw_pwrite_stream> OS);
  
    // Emit output using the new pass manager for the optimization pipeline. This
    // is the default.
    void EmitAssembly(BackendAction Action,
                      std::unique_ptr<raw_pwrite_stream> OS);
  };
  
  // We need this wrapper to access LangOpts and CGOpts from extension functions
  // that we add to the PassManagerBuilder.
  class PassManagerBuilderWrapper : public PassManagerBuilder {
  public:
    PassManagerBuilderWrapper(const Triple &TargetTriple,
                              const CodeGenOptions &CGOpts,
                              const LangOptions &LangOpts)
        : PassManagerBuilder(), TargetTriple(TargetTriple), CGOpts(CGOpts),
          LangOpts(LangOpts) {}
    const Triple &getTargetTriple() const { return TargetTriple; }
    const CodeGenOptions &getCGOpts() const { return CGOpts; }
    const LangOptions &getLangOpts() const { return LangOpts; }
  
  private:
    const Triple &TargetTriple;
    const CodeGenOptions &CGOpts;
    const LangOptions &LangOpts;
  };
  }
  
  static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
    if (Builder.OptLevel > 0)
      PM.add(createObjCARCAPElimPass());
  }
  
  static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
    if (Builder.OptLevel > 0)
      PM.add(createObjCARCExpandPass());
  }
  
  static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
    if (Builder.OptLevel > 0)
      PM.add(createObjCARCOptPass());
  }
  
  static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
                                       legacy::PassManagerBase &PM) {
    PM.add(createAddDiscriminatorsPass());
  }
  
  static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
                                    legacy::PassManagerBase &PM) {
    PM.add(createBoundsCheckingLegacyPass());
  }
  
  static SanitizerCoverageOptions
  getSancovOptsFromCGOpts(const CodeGenOptions &CGOpts) {
    SanitizerCoverageOptions Opts;
    Opts.CoverageType =
        static_cast<SanitizerCoverageOptions::Type>(CGOpts.SanitizeCoverageType);
    Opts.IndirectCalls = CGOpts.SanitizeCoverageIndirectCalls;
    Opts.TraceBB = CGOpts.SanitizeCoverageTraceBB;
    Opts.TraceCmp = CGOpts.SanitizeCoverageTraceCmp;
    Opts.TraceDiv = CGOpts.SanitizeCoverageTraceDiv;
    Opts.TraceGep = CGOpts.SanitizeCoverageTraceGep;
    Opts.Use8bitCounters = CGOpts.SanitizeCoverage8bitCounters;
    Opts.TracePC = CGOpts.SanitizeCoverageTracePC;
    Opts.TracePCGuard = CGOpts.SanitizeCoverageTracePCGuard;
    Opts.NoPrune = CGOpts.SanitizeCoverageNoPrune;
    Opts.Inline8bitCounters = CGOpts.SanitizeCoverageInline8bitCounters;
    Opts.InlineBoolFlag = CGOpts.SanitizeCoverageInlineBoolFlag;
    Opts.PCTable = CGOpts.SanitizeCoveragePCTable;
    Opts.StackDepth = CGOpts.SanitizeCoverageStackDepth;
    return Opts;
  }
  
  static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
                                       legacy::PassManagerBase &PM) {
    const PassManagerBuilderWrapper &BuilderWrapper =
        static_cast<const PassManagerBuilderWrapper &>(Builder);
    const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
    auto Opts = getSancovOptsFromCGOpts(CGOpts);
    PM.add(createModuleSanitizerCoverageLegacyPassPass(
        Opts, CGOpts.SanitizeCoverageAllowlistFiles,
        CGOpts.SanitizeCoverageIgnorelistFiles));
  }
  
  // Check if ASan should use GC-friendly instrumentation for globals.
  // First of all, there is no point if -fdata-sections is off (expect for MachO,
  // where this is not a factor). Also, on ELF this feature requires an assembler
  // extension that only works with -integrated-as at the moment.
  static bool asanUseGlobalsGC(const Triple &T, const CodeGenOptions &CGOpts) {
    if (!CGOpts.SanitizeAddressGlobalsDeadStripping)
      return false;
    switch (T.getObjectFormat()) {
    case Triple::MachO:
    case Triple::COFF:
      return true;
    case Triple::ELF:
      return CGOpts.DataSections && !CGOpts.DisableIntegratedAS;
    case Triple::GOFF:
      llvm::report_fatal_error("ASan not implemented for GOFF");
    case Triple::XCOFF:
      llvm::report_fatal_error("ASan not implemented for XCOFF.");
    case Triple::Wasm:
    case Triple::UnknownObjectFormat:
      break;
    }
    return false;
  }
  
  static void addMemProfilerPasses(const PassManagerBuilder &Builder,
                                   legacy::PassManagerBase &PM) {
    PM.add(createMemProfilerFunctionPass());
    PM.add(createModuleMemProfilerLegacyPassPass());
  }
  
  static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
                                        legacy::PassManagerBase &PM) {
    const PassManagerBuilderWrapper &BuilderWrapper =
        static_cast<const PassManagerBuilderWrapper&>(Builder);
    const Triple &T = BuilderWrapper.getTargetTriple();
    const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
    bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Address);
    bool UseAfterScope = CGOpts.SanitizeAddressUseAfterScope;
    bool UseOdrIndicator = CGOpts.SanitizeAddressUseOdrIndicator;
    bool UseGlobalsGC = asanUseGlobalsGC(T, CGOpts);
    llvm::AsanDtorKind DestructorKind = CGOpts.getSanitizeAddressDtor();
    llvm::AsanDetectStackUseAfterReturnMode UseAfterReturn =
        CGOpts.getSanitizeAddressUseAfterReturn();
    PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/ false, Recover,
                                              UseAfterScope, UseAfterReturn));
    PM.add(createModuleAddressSanitizerLegacyPassPass(
        /*CompileKernel*/ false, Recover, UseGlobalsGC, UseOdrIndicator,
        DestructorKind));
  }
  
  static void addKernelAddressSanitizerPasses(const PassManagerBuilder &Builder,
                                              legacy::PassManagerBase &PM) {
    PM.add(createAddressSanitizerFunctionPass(
        /*CompileKernel*/ true, /*Recover*/ true, /*UseAfterScope*/ false,
        /*UseAfterReturn*/ llvm::AsanDetectStackUseAfterReturnMode::Never));
    PM.add(createModuleAddressSanitizerLegacyPassPass(
        /*CompileKernel*/ true, /*Recover*/ true, /*UseGlobalsGC*/ true,
        /*UseOdrIndicator*/ false));
  }
  
  static void addHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
                                              legacy::PassManagerBase &PM) {
    const PassManagerBuilderWrapper &BuilderWrapper =
        static_cast<const PassManagerBuilderWrapper &>(Builder);
    const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
    bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
    PM.add(createHWAddressSanitizerLegacyPassPass(
        /*CompileKernel*/ false, Recover,
        /*DisableOptimization*/ CGOpts.OptimizationLevel == 0));
  }
  
  static void addKernelHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
                                                legacy::PassManagerBase &PM) {
    const PassManagerBuilderWrapper &BuilderWrapper =
        static_cast<const PassManagerBuilderWrapper &>(Builder);
    const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
    PM.add(createHWAddressSanitizerLegacyPassPass(
        /*CompileKernel*/ true, /*Recover*/ true,
        /*DisableOptimization*/ CGOpts.OptimizationLevel == 0));
  }
  
  static void addGeneralOptsForMemorySanitizer(const PassManagerBuilder &Builder,
                                               legacy::PassManagerBase &PM,
                                               bool CompileKernel) {
    const PassManagerBuilderWrapper &BuilderWrapper =
        static_cast<const PassManagerBuilderWrapper&>(Builder);
    const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
    int TrackOrigins = CGOpts.SanitizeMemoryTrackOrigins;
    bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Memory);
    PM.add(createMemorySanitizerLegacyPassPass(
        MemorySanitizerOptions{TrackOrigins, Recover, CompileKernel}));
  
    // MemorySanitizer inserts complex instrumentation that mostly follows
    // the logic of the original code, but operates on "shadow" values.
    // It can benefit from re-running some general purpose optimization passes.
    if (Builder.OptLevel > 0) {
      PM.add(createEarlyCSEPass());
      PM.add(createReassociatePass());
      PM.add(createLICMPass());
      PM.add(createGVNPass());
      PM.add(createInstructionCombiningPass());
      PM.add(createDeadStoreEliminationPass());
    }
  }
  
  static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
                                     legacy::PassManagerBase &PM) {
    addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ false);
  }
  
  static void addKernelMemorySanitizerPass(const PassManagerBuilder &Builder,
                                           legacy::PassManagerBase &PM) {
    addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ true);
  }
  
  static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
                                     legacy::PassManagerBase &PM) {
    PM.add(createThreadSanitizerLegacyPassPass());
  }
  
  static void addDataFlowSanitizerPass(const PassManagerBuilder &Builder,
                                       legacy::PassManagerBase &PM) {
    const PassManagerBuilderWrapper &BuilderWrapper =
        static_cast<const PassManagerBuilderWrapper&>(Builder);
    const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
    PM.add(createDataFlowSanitizerLegacyPassPass(LangOpts.NoSanitizeFiles));
  }
  
  static void addEntryExitInstrumentationPass(const PassManagerBuilder &Builder,
                                              legacy::PassManagerBase &PM) {
    PM.add(createEntryExitInstrumenterPass());
  }
  
  static void
  addPostInlineEntryExitInstrumentationPass(const PassManagerBuilder &Builder,
                                            legacy::PassManagerBase &PM) {
    PM.add(createPostInlineEntryExitInstrumenterPass());
  }
  
  static TargetLibraryInfoImpl *createTLII(llvm::Triple &TargetTriple,
                                           const CodeGenOptions &CodeGenOpts) {
    TargetLibraryInfoImpl *TLII = new TargetLibraryInfoImpl(TargetTriple);
  
    switch (CodeGenOpts.getVecLib()) {
    case CodeGenOptions::Accelerate:
      TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::Accelerate);
      break;
    case CodeGenOptions::LIBMVEC:
      switch(TargetTriple.getArch()) {
        default:
          break;
        case llvm::Triple::x86_64:
          TLII->addVectorizableFunctionsFromVecLib
                  (TargetLibraryInfoImpl::LIBMVEC_X86);
          break;
      }
      break;
    case CodeGenOptions::MASSV:
      TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::MASSV);
      break;
    case CodeGenOptions::SVML:
      TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::SVML);
      break;
    case CodeGenOptions::Darwin_libsystem_m:
      TLII->addVectorizableFunctionsFromVecLib(
          TargetLibraryInfoImpl::DarwinLibSystemM);
      break;
    default:
      break;
    }
    return TLII;
  }
  
  static void addSymbolRewriterPass(const CodeGenOptions &Opts,
                                    legacy::PassManager *MPM) {
    llvm::SymbolRewriter::RewriteDescriptorList DL;
  
    llvm::SymbolRewriter::RewriteMapParser MapParser;
    for (const auto &MapFile : Opts.RewriteMapFiles)
      MapParser.parse(MapFile, &DL);
  
    MPM->add(createRewriteSymbolsPass(DL));
  }
  
  static CodeGenOpt::Level getCGOptLevel(const CodeGenOptions &CodeGenOpts) {
    switch (CodeGenOpts.OptimizationLevel) {
    default:
      llvm_unreachable("Invalid optimization level!");
    case 0:
      return CodeGenOpt::None;
    case 1:
      return CodeGenOpt::Less;
    case 2:
      return CodeGenOpt::Default; // O2/Os/Oz
    case 3:
      return CodeGenOpt::Aggressive;
    }
  }
  
  static Optional<llvm::CodeModel::Model>
  getCodeModel(const CodeGenOptions &CodeGenOpts) {
    unsigned CodeModel = llvm::StringSwitch<unsigned>(CodeGenOpts.CodeModel)
                             .Case("tiny", llvm::CodeModel::Tiny)
                             .Case("small", llvm::CodeModel::Small)
                             .Case("kernel", llvm::CodeModel::Kernel)
                             .Case("medium", llvm::CodeModel::Medium)
                             .Case("large", llvm::CodeModel::Large)
                             .Case("default", ~1u)
                             .Default(~0u);
    assert(CodeModel != ~0u && "invalid code model!");
    if (CodeModel == ~1u)
      return None;
    return static_cast<llvm::CodeModel::Model>(CodeModel);
  }
  
  static CodeGenFileType getCodeGenFileType(BackendAction Action) {
    if (Action == Backend_EmitObj)
      return CGFT_ObjectFile;
    else if (Action == Backend_EmitMCNull)
      return CGFT_Null;
    else {
      assert(Action == Backend_EmitAssembly && "Invalid action!");
      return CGFT_AssemblyFile;
    }
  }
  
  static bool initTargetOptions(DiagnosticsEngine &Diags,
                                llvm::TargetOptions &Options,
                                const CodeGenOptions &CodeGenOpts,
                                const clang::TargetOptions &TargetOpts,
                                const LangOptions &LangOpts,
                                const HeaderSearchOptions &HSOpts) {
    switch (LangOpts.getThreadModel()) {
    case LangOptions::ThreadModelKind::POSIX:
      Options.ThreadModel = llvm::ThreadModel::POSIX;
      break;
    case LangOptions::ThreadModelKind::Single:
      Options.ThreadModel = llvm::ThreadModel::Single;
      break;
    }
  
    // Set float ABI type.
    assert((CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp" ||
            CodeGenOpts.FloatABI == "hard" || CodeGenOpts.FloatABI.empty()) &&
           "Invalid Floating Point ABI!");
    Options.FloatABIType =
        llvm::StringSwitch<llvm::FloatABI::ABIType>(CodeGenOpts.FloatABI)
            .Case("soft", llvm::FloatABI::Soft)
            .Case("softfp", llvm::FloatABI::Soft)
            .Case("hard", llvm::FloatABI::Hard)
            .Default(llvm::FloatABI::Default);
  
    // Set FP fusion mode.
    switch (LangOpts.getDefaultFPContractMode()) {
    case LangOptions::FPM_Off:
      // Preserve any contraction performed by the front-end.  (Strict performs
      // splitting of the muladd intrinsic in the backend.)
      Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
      break;
    case LangOptions::FPM_On:
    case LangOptions::FPM_FastHonorPragmas:
      Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
      break;
    case LangOptions::FPM_Fast:
      Options.AllowFPOpFusion = llvm::FPOpFusion::Fast;
      break;
    }
  
    Options.BinutilsVersion =
        llvm::TargetMachine::parseBinutilsVersion(CodeGenOpts.BinutilsVersion);
    Options.UseInitArray = CodeGenOpts.UseInitArray;
    Options.DisableIntegratedAS = CodeGenOpts.DisableIntegratedAS;
    Options.CompressDebugSections = CodeGenOpts.getCompressDebugSections();
    Options.RelaxELFRelocations = CodeGenOpts.RelaxELFRelocations;
  
    // Set EABI version.
    Options.EABIVersion = TargetOpts.EABIVersion;
  
    if (LangOpts.hasSjLjExceptions())
      Options.ExceptionModel = llvm::ExceptionHandling::SjLj;
    if (LangOpts.hasSEHExceptions())
      Options.ExceptionModel = llvm::ExceptionHandling::WinEH;
    if (LangOpts.hasDWARFExceptions())
      Options.ExceptionModel = llvm::ExceptionHandling::DwarfCFI;
    if (LangOpts.hasWasmExceptions())
      Options.ExceptionModel = llvm::ExceptionHandling::Wasm;
  
    Options.NoInfsFPMath = LangOpts.NoHonorInfs;
    Options.NoNaNsFPMath = LangOpts.NoHonorNaNs;
    Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
    Options.UnsafeFPMath = LangOpts.UnsafeFPMath;
    Options.ApproxFuncFPMath = LangOpts.ApproxFunc;
  
    Options.BBSections =
        llvm::StringSwitch<llvm::BasicBlockSection>(CodeGenOpts.BBSections)
            .Case("all", llvm::BasicBlockSection::All)
            .Case("labels", llvm::BasicBlockSection::Labels)
            .StartsWith("list=", llvm::BasicBlockSection::List)
            .Case("none", llvm::BasicBlockSection::None)
            .Default(llvm::BasicBlockSection::None);
  
    if (Options.BBSections == llvm::BasicBlockSection::List) {
      ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
          MemoryBuffer::getFile(CodeGenOpts.BBSections.substr(5));
      if (!MBOrErr) {
        Diags.Report(diag::err_fe_unable_to_load_basic_block_sections_file)
            << MBOrErr.getError().message();
        return false;
      }
      Options.BBSectionsFuncListBuf = std::move(*MBOrErr);
    }
  
    Options.EnableMachineFunctionSplitter = CodeGenOpts.SplitMachineFunctions;
    Options.FunctionSections = CodeGenOpts.FunctionSections;
    Options.DataSections = CodeGenOpts.DataSections;
    Options.IgnoreXCOFFVisibility = LangOpts.IgnoreXCOFFVisibility;
    Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
    Options.UniqueBasicBlockSectionNames =
        CodeGenOpts.UniqueBasicBlockSectionNames;
    Options.TLSSize = CodeGenOpts.TLSSize;
    Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
    Options.ExplicitEmulatedTLS = CodeGenOpts.ExplicitEmulatedTLS;
    Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
    Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
    Options.StackUsageOutput = CodeGenOpts.StackUsageOutput;
    Options.EmitAddrsig = CodeGenOpts.Addrsig;
    Options.ForceDwarfFrameSection = CodeGenOpts.ForceDwarfFrameSection;
    Options.EmitCallSiteInfo = CodeGenOpts.EmitCallSiteInfo;
    Options.EnableAIXExtendedAltivecABI = CodeGenOpts.EnableAIXExtendedAltivecABI;
    Options.ValueTrackingVariableLocations =
        CodeGenOpts.ValueTrackingVariableLocations;
    Options.XRayOmitFunctionIndex = CodeGenOpts.XRayOmitFunctionIndex;
    Options.LoopAlignment = CodeGenOpts.LoopAlignment;
  
    switch (CodeGenOpts.getSwiftAsyncFramePointer()) {
    case CodeGenOptions::SwiftAsyncFramePointerKind::Auto:
      Options.SwiftAsyncFramePointer =
          SwiftAsyncFramePointerMode::DeploymentBased;
      break;
  
    case CodeGenOptions::SwiftAsyncFramePointerKind::Always:
      Options.SwiftAsyncFramePointer = SwiftAsyncFramePointerMode::Always;
      break;
  
    case CodeGenOptions::SwiftAsyncFramePointerKind::Never:
      Options.SwiftAsyncFramePointer = SwiftAsyncFramePointerMode::Never;
      break;
    }
  
    Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
    Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
    Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
    Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
    Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
    Options.MCOptions.MCIncrementalLinkerCompatible =
        CodeGenOpts.IncrementalLinkerCompatible;
    Options.MCOptions.MCFatalWarnings = CodeGenOpts.FatalWarnings;
    Options.MCOptions.MCNoWarn = CodeGenOpts.NoWarn;
    Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
    Options.MCOptions.Dwarf64 = CodeGenOpts.Dwarf64;
    Options.MCOptions.PreserveAsmComments = CodeGenOpts.PreserveAsmComments;
    Options.MCOptions.ABIName = TargetOpts.ABI;
    for (const auto &Entry : HSOpts.UserEntries)
      if (!Entry.IsFramework &&
          (Entry.Group == frontend::IncludeDirGroup::Quoted ||
           Entry.Group == frontend::IncludeDirGroup::Angled ||
           Entry.Group == frontend::IncludeDirGroup::System))
        Options.MCOptions.IASSearchPaths.push_back(
            Entry.IgnoreSysRoot ? Entry.Path : HSOpts.Sysroot + Entry.Path);
    Options.MCOptions.Argv0 = CodeGenOpts.Argv0;
    Options.MCOptions.CommandLineArgs = CodeGenOpts.CommandLineArgs;
    Options.DebugStrictDwarf = CodeGenOpts.DebugStrictDwarf;
  
    return true;
  }
  
  static Optional<GCOVOptions> getGCOVOptions(const CodeGenOptions &CodeGenOpts,
                                              const LangOptions &LangOpts) {
    if (!CodeGenOpts.EmitGcovArcs && !CodeGenOpts.EmitGcovNotes)
      return None;
    // Not using 'GCOVOptions::getDefault' allows us to avoid exiting if
    // LLVM's -default-gcov-version flag is set to something invalid.
    GCOVOptions Options;
    Options.EmitNotes = CodeGenOpts.EmitGcovNotes;
    Options.EmitData = CodeGenOpts.EmitGcovArcs;
    llvm::copy(CodeGenOpts.CoverageVersion, std::begin(Options.Version));
    Options.NoRedZone = CodeGenOpts.DisableRedZone;
    Options.Filter = CodeGenOpts.ProfileFilterFiles;
    Options.Exclude = CodeGenOpts.ProfileExcludeFiles;
    Options.Atomic = CodeGenOpts.AtomicProfileUpdate;
    return Options;
  }
  
  static Optional<InstrProfOptions>
  getInstrProfOptions(const CodeGenOptions &CodeGenOpts,
                      const LangOptions &LangOpts) {
    if (!CodeGenOpts.hasProfileClangInstr())
      return None;
    InstrProfOptions Options;
    Options.NoRedZone = CodeGenOpts.DisableRedZone;
    Options.InstrProfileOutput = CodeGenOpts.InstrProfileOutput;
    Options.Atomic = CodeGenOpts.AtomicProfileUpdate;
    return Options;
  }
  
  void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
                                        legacy::FunctionPassManager &FPM) {
    // Handle disabling of all LLVM passes, where we want to preserve the
    // internal module before any optimization.
    if (CodeGenOpts.DisableLLVMPasses)
      return;
  
    // Figure out TargetLibraryInfo.  This needs to be added to MPM and FPM
    // manually (and not via PMBuilder), since some passes (eg. InstrProfiling)
    // are inserted before PMBuilder ones - they'd get the default-constructed
    // TLI with an unknown target otherwise.
    Triple TargetTriple(TheModule->getTargetTriple());
    std::unique_ptr<TargetLibraryInfoImpl> TLII(
        createTLII(TargetTriple, CodeGenOpts));
  
    // If we reached here with a non-empty index file name, then the index file
    // was empty and we are not performing ThinLTO backend compilation (used in
    // testing in a distributed build environment). Drop any the type test
    // assume sequences inserted for whole program vtables so that codegen doesn't
    // complain.
    if (!CodeGenOpts.ThinLTOIndexFile.empty())
      MPM.add(createLowerTypeTestsPass(/*ExportSummary=*/nullptr,
                                       /*ImportSummary=*/nullptr,
                                       /*DropTypeTests=*/true));
  
    PassManagerBuilderWrapper PMBuilder(TargetTriple, CodeGenOpts, LangOpts);
  
    // At O0 and O1 we only run the always inliner which is more efficient. At
    // higher optimization levels we run the normal inliner.
    if (CodeGenOpts.OptimizationLevel <= 1) {
      bool InsertLifetimeIntrinsics = ((CodeGenOpts.OptimizationLevel != 0 &&
                                        !CodeGenOpts.DisableLifetimeMarkers) ||
                                       LangOpts.Coroutines);
      PMBuilder.Inliner = createAlwaysInlinerLegacyPass(InsertLifetimeIntrinsics);
    } else {
      // We do not want to inline hot callsites for SamplePGO module-summary build
      // because profile annotation will happen again in ThinLTO backend, and we
      // want the IR of the hot path to match the profile.
      PMBuilder.Inliner = createFunctionInliningPass(
          CodeGenOpts.OptimizationLevel, CodeGenOpts.OptimizeSize,
          (!CodeGenOpts.SampleProfileFile.empty() &&
           CodeGenOpts.PrepareForThinLTO));
    }
  
    PMBuilder.OptLevel = CodeGenOpts.OptimizationLevel;
    PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
    PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
    PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
    // Only enable CGProfilePass when using integrated assembler, since
    // non-integrated assemblers don't recognize .cgprofile section.
    PMBuilder.CallGraphProfile = !CodeGenOpts.DisableIntegratedAS;
  
    PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
    // Loop interleaving in the loop vectorizer has historically been set to be
    // enabled when loop unrolling is enabled.
    PMBuilder.LoopsInterleaved = CodeGenOpts.UnrollLoops;
    PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
    PMBuilder.PrepareForThinLTO = CodeGenOpts.PrepareForThinLTO;
    PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
    PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
  
    MPM.add(new TargetLibraryInfoWrapperPass(*TLII));
  
    if (TM)
      TM->adjustPassManager(PMBuilder);
  
    if (CodeGenOpts.DebugInfoForProfiling ||
        !CodeGenOpts.SampleProfileFile.empty())
      PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
                             addAddDiscriminatorsPass);
  
    // In ObjC ARC mode, add the main ARC optimization passes.
    if (LangOpts.ObjCAutoRefCount) {
      PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
                             addObjCARCExpandPass);
      PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
                             addObjCARCAPElimPass);
      PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
                             addObjCARCOptPass);
    }
  
    if (LangOpts.Coroutines)
      addCoroutinePassesToExtensionPoints(PMBuilder);
  
    if (!CodeGenOpts.MemoryProfileOutput.empty()) {
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addMemProfilerPasses);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addMemProfilerPasses);
    }
  
    if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds)) {
      PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
                             addBoundsCheckingPass);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addBoundsCheckingPass);
    }
  
    if (CodeGenOpts.hasSanitizeCoverage()) {
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addSanitizerCoveragePass);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addSanitizerCoveragePass);
    }
  
    if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addAddressSanitizerPasses);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addAddressSanitizerPasses);
    }
  
    if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addKernelAddressSanitizerPasses);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addKernelAddressSanitizerPasses);
    }
  
    if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addHWAddressSanitizerPasses);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addHWAddressSanitizerPasses);
    }
  
    if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addKernelHWAddressSanitizerPasses);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addKernelHWAddressSanitizerPasses);
    }
  
    if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addMemorySanitizerPass);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addMemorySanitizerPass);
    }
  
    if (LangOpts.Sanitize.has(SanitizerKind::KernelMemory)) {
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addKernelMemorySanitizerPass);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addKernelMemorySanitizerPass);
    }
  
    if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addThreadSanitizerPass);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addThreadSanitizerPass);
    }
  
    if (LangOpts.Sanitize.has(SanitizerKind::DataFlow)) {
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addDataFlowSanitizerPass);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addDataFlowSanitizerPass);
    }
  
    if (CodeGenOpts.InstrumentFunctions ||
        CodeGenOpts.InstrumentFunctionEntryBare ||
        CodeGenOpts.InstrumentFunctionsAfterInlining ||
        CodeGenOpts.InstrumentForProfiling) {
      PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
                             addEntryExitInstrumentationPass);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addEntryExitInstrumentationPass);
      PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                             addPostInlineEntryExitInstrumentationPass);
      PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                             addPostInlineEntryExitInstrumentationPass);
    }
  
    // Set up the per-function pass manager.
    FPM.add(new TargetLibraryInfoWrapperPass(*TLII));
    if (CodeGenOpts.VerifyModule)
      FPM.add(createVerifierPass());
  
    // Set up the per-module pass manager.
    if (!CodeGenOpts.RewriteMapFiles.empty())
      addSymbolRewriterPass(CodeGenOpts, &MPM);
  
    if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts, LangOpts)) {
      MPM.add(createGCOVProfilerPass(*Options));
      if (CodeGenOpts.getDebugInfo() == codegenoptions::NoDebugInfo)
        MPM.add(createStripSymbolsPass(true));
    }
  
    if (Optional<InstrProfOptions> Options =
            getInstrProfOptions(CodeGenOpts, LangOpts))
      MPM.add(createInstrProfilingLegacyPass(*Options, false));
  
    bool hasIRInstr = false;
    if (CodeGenOpts.hasProfileIRInstr()) {
      PMBuilder.EnablePGOInstrGen = true;
      hasIRInstr = true;
    }
    if (CodeGenOpts.hasProfileCSIRInstr()) {
      assert(!CodeGenOpts.hasProfileCSIRUse() &&
             "Cannot have both CSProfileUse pass and CSProfileGen pass at the "
             "same time");
      assert(!hasIRInstr &&
             "Cannot have both ProfileGen pass and CSProfileGen pass at the "
             "same time");
      PMBuilder.EnablePGOCSInstrGen = true;
      hasIRInstr = true;
    }
    if (hasIRInstr) {
      if (!CodeGenOpts.InstrProfileOutput.empty())
        PMBuilder.PGOInstrGen = CodeGenOpts.InstrProfileOutput;
      else
        PMBuilder.PGOInstrGen = std::string(DefaultProfileGenName);
    }
    if (CodeGenOpts.hasProfileIRUse()) {
      PMBuilder.PGOInstrUse = CodeGenOpts.ProfileInstrumentUsePath;
      PMBuilder.EnablePGOCSInstrUse = CodeGenOpts.hasProfileCSIRUse();
    }
  
    if (!CodeGenOpts.SampleProfileFile.empty())
      PMBuilder.PGOSampleUse = CodeGenOpts.SampleProfileFile;
  
    PMBuilder.populateFunctionPassManager(FPM);
    PMBuilder.populateModulePassManager(MPM);
  }
  
  static void setCommandLineOpts(const CodeGenOptions &CodeGenOpts) {
    SmallVector<const char *, 16> BackendArgs;
    BackendArgs.push_back("clang"); // Fake program name.
    if (!CodeGenOpts.DebugPass.empty()) {
      BackendArgs.push_back("-debug-pass");
      BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
    }
    if (!CodeGenOpts.LimitFloatPrecision.empty()) {
      BackendArgs.push_back("-limit-float-precision");
      BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
    }
    // Check for the default "clang" invocation that won't set any cl::opt values.
    // Skip trying to parse the command line invocation to avoid the issues
    // described below.
    if (BackendArgs.size() == 1)
      return;
    BackendArgs.push_back(nullptr);
    // FIXME: The command line parser below is not thread-safe and shares a global
    // state, so this call might crash or overwrite the options of another Clang
    // instance in the same process.
    llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
                                      BackendArgs.data());
  }
  
  void EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
    // Create the TargetMachine for generating code.
    std::string Error;
    std::string Triple = TheModule->getTargetTriple();
    const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
    if (!TheTarget) {
      if (MustCreateTM)
        Diags.Report(diag::err_fe_unable_to_create_target) << Error;
      return;
    }
  
    Optional<llvm::CodeModel::Model> CM = getCodeModel(CodeGenOpts);
    std::string FeaturesStr =
        llvm::join(TargetOpts.Features.begin(), TargetOpts.Features.end(), ",");
    llvm::Reloc::Model RM = CodeGenOpts.RelocationModel;
    CodeGenOpt::Level OptLevel = getCGOptLevel(CodeGenOpts);
  
    llvm::TargetOptions Options;
    if (!initTargetOptions(Diags, Options, CodeGenOpts, TargetOpts, LangOpts,
                           HSOpts))
      return;
    TM.reset(TheTarget->createTargetMachine(Triple, TargetOpts.CPU, FeaturesStr,
                                            Options, RM, CM, OptLevel));
  }
  
  bool EmitAssemblyHelper::AddEmitPasses(legacy::PassManager &CodeGenPasses,
                                         BackendAction Action,
                                         raw_pwrite_stream &OS,
                                         raw_pwrite_stream *DwoOS) {
    // Add LibraryInfo.
    llvm::Triple TargetTriple(TheModule->getTargetTriple());
    std::unique_ptr<TargetLibraryInfoImpl> TLII(
        createTLII(TargetTriple, CodeGenOpts));
    CodeGenPasses.add(new TargetLibraryInfoWrapperPass(*TLII));
  
    // Normal mode, emit a .s or .o file by running the code generator. Note,
    // this also adds codegenerator level optimization passes.
    CodeGenFileType CGFT = getCodeGenFileType(Action);
  
    // Add ObjC ARC final-cleanup optimizations. This is done as part of the
    // "codegen" passes so that it isn't run multiple times when there is
    // inlining happening.
    if (CodeGenOpts.OptimizationLevel > 0)
      CodeGenPasses.add(createObjCARCContractPass());
  
    if (TM->addPassesToEmitFile(CodeGenPasses, OS, DwoOS, CGFT,
                                /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
      Diags.Report(diag::err_fe_unable_to_interface_with_target);
      return false;
    }
  
    return true;
  }
  
  void EmitAssemblyHelper::EmitAssemblyWithLegacyPassManager(
      BackendAction Action, std::unique_ptr<raw_pwrite_stream> OS) {
    TimeRegion Region(CodeGenOpts.TimePasses ? &CodeGenerationTime : nullptr);
  
    setCommandLineOpts(CodeGenOpts);
  
    bool UsesCodeGen = (Action != Backend_EmitNothing &&
                        Action != Backend_EmitBC &&
                        Action != Backend_EmitLL);
    CreateTargetMachine(UsesCodeGen);
  
    if (UsesCodeGen && !TM)
      return;
    if (TM)
      TheModule->setDataLayout(TM->createDataLayout());
  
    DebugifyCustomPassManager PerModulePasses;
    DebugInfoPerPassMap DIPreservationMap;
    if (CodeGenOpts.EnableDIPreservationVerify) {
      PerModulePasses.setDebugifyMode(DebugifyMode::OriginalDebugInfo);
      PerModulePasses.setDIPreservationMap(DIPreservationMap);
  
      if (!CodeGenOpts.DIBugsReportFilePath.empty())
        PerModulePasses.setOrigDIVerifyBugsReportFilePath(
            CodeGenOpts.DIBugsReportFilePath);
    }
    PerModulePasses.add(
        createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
  
    legacy::FunctionPassManager PerFunctionPasses(TheModule);
    PerFunctionPasses.add(
        createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
  
    CreatePasses(PerModulePasses, PerFunctionPasses);
  
    legacy::PassManager CodeGenPasses;
    CodeGenPasses.add(
        createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
  
    std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
  
    // Eliminate dead arguments from SPIR kernels in SYCL environment.
    // Run DAE when LLVM optimizations are applied as well.
    if (LangOpts.SYCLIsDevice && !CodeGenOpts.DisableLLVMPasses &&
        LangOpts.EnableDAEInSpirKernels)
      PerModulePasses.add(createDeadArgEliminationSYCLPass());
  
    // Add SPIRITTAnnotations pass to the pass manager if
    // -fsycl-instrument-device-code option was passed. This option can be
    // used only with spir triple.
    if (CodeGenOpts.SPIRITTAnnotations) {
      if (!llvm::Triple(TheModule->getTargetTriple()).isSPIR())
        llvm::report_fatal_error(
            "ITT annotations can only by added to a module with spir target");
      PerModulePasses.add(createSPIRITTAnnotationsLegacyPass());
    }
  
    // Allocate static local memory in SYCL kernel scope for each allocation call.
    if (LangOpts.SYCLIsDevice) {
      // Group local memory pass depends on inlining. Turn it on even in case if
      // all llvm passes or SYCL early optimizations are disabled.
      // FIXME: Remove this workaround when dependency on inlining is eliminated.
      if (CodeGenOpts.DisableLLVMPasses)
        PerModulePasses.add(createAlwaysInlinerLegacyPass(false));
      PerModulePasses.add(createSYCLLowerWGLocalMemoryLegacyPass());
    }
  
    switch (Action) {
    case Backend_EmitNothing:
      break;
  
    case Backend_EmitBC:
      if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
        if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
          ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
          if (!ThinLinkOS)
            return;
        }
        TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
                                 CodeGenOpts.EnableSplitLTOUnit);
        PerModulePasses.add(createWriteThinLTOBitcodePass(
            *OS, ThinLinkOS ? &ThinLinkOS->os() : nullptr));
      } else {
        // Emit a module summary by default for Regular LTO except for ld64
        // targets
        bool EmitLTOSummary =
            (CodeGenOpts.PrepareForLTO &&
             !CodeGenOpts.DisableLLVMPasses &&
             llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
                 llvm::Triple::Apple);
        if (EmitLTOSummary) {
          if (!TheModule->getModuleFlag("ThinLTO"))
            TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
          TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
                                   uint32_t(1));
        }
  
        PerModulePasses.add(createBitcodeWriterPass(
            *OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
      }
      break;
  
    case Backend_EmitLL:
      PerModulePasses.add(
          createPrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
      break;
  
    default:
      if (!CodeGenOpts.SplitDwarfOutput.empty()) {
        DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
        if (!DwoOS)
          return;
      }
      if (!AddEmitPasses(CodeGenPasses, Action, *OS,
                         DwoOS ? &DwoOS->os() : nullptr))
        return;
    }
  
    // Before executing passes, print the final values of the LLVM options.
    cl::PrintOptionValues();
  
    // Run passes. For now we do all passes at once, but eventually we
    // would like to have the option of streaming code generation.
  
    {
      PrettyStackTraceString CrashInfo("Per-function optimization");
      llvm::TimeTraceScope TimeScope("PerFunctionPasses");
  
      PerFunctionPasses.doInitialization();
      for (Function &F : *TheModule)
        if (!F.isDeclaration())
          PerFunctionPasses.run(F);
      PerFunctionPasses.doFinalization();
    }
  
    {
      PrettyStackTraceString CrashInfo("Per-module optimization passes");
      llvm::TimeTraceScope TimeScope("PerModulePasses");
      PerModulePasses.run(*TheModule);
    }
  
    {
      PrettyStackTraceString CrashInfo("Code generation");
      llvm::TimeTraceScope TimeScope("CodeGenPasses");
      CodeGenPasses.run(*TheModule);
    }
  
    if (ThinLinkOS)
      ThinLinkOS->keep();
    if (DwoOS)
      DwoOS->keep();
  }
  
  static OptimizationLevel mapToLevel(const CodeGenOptions &Opts) {
    switch (Opts.OptimizationLevel) {
    default:
      llvm_unreachable("Invalid optimization level!");
  
    case 0:
      return OptimizationLevel::O0;
  
    case 1:
      return OptimizationLevel::O1;
  
    case 2:
      switch (Opts.OptimizeSize) {
      default:
        llvm_unreachable("Invalid optimization level for size!");
  
      case 0:
        return OptimizationLevel::O2;
  
      case 1:
        return OptimizationLevel::Os;
  
      case 2:
        return OptimizationLevel::Oz;
      }
  
    case 3:
      return OptimizationLevel::O3;
    }
  }
  
  static void addSanitizers(const Triple &TargetTriple,
                            const CodeGenOptions &CodeGenOpts,
                            const LangOptions &LangOpts, PassBuilder &PB) {
    PB.registerOptimizerLastEPCallback([&](ModulePassManager &MPM,
                                           OptimizationLevel Level) {
      if (CodeGenOpts.hasSanitizeCoverage()) {
        auto SancovOpts = getSancovOptsFromCGOpts(CodeGenOpts);
        MPM.addPass(ModuleSanitizerCoveragePass(
            SancovOpts, CodeGenOpts.SanitizeCoverageAllowlistFiles,
            CodeGenOpts.SanitizeCoverageIgnorelistFiles));
      }
  
      auto MSanPass = [&](SanitizerMask Mask, bool CompileKernel) {
        if (LangOpts.Sanitize.has(Mask)) {
          int TrackOrigins = CodeGenOpts.SanitizeMemoryTrackOrigins;
          bool Recover = CodeGenOpts.SanitizeRecover.has(Mask);
  
          MPM.addPass(
              ModuleMemorySanitizerPass({TrackOrigins, Recover, CompileKernel}));
          FunctionPassManager FPM;
          FPM.addPass(
              MemorySanitizerPass({TrackOrigins, Recover, CompileKernel}));
          if (Level != OptimizationLevel::O0) {
            // MemorySanitizer inserts complex instrumentation that mostly
            // follows the logic of the original code, but operates on
            // "shadow" values. It can benefit from re-running some
            // general purpose optimization passes.
            FPM.addPass(EarlyCSEPass());
            // TODO: Consider add more passes like in
            // addGeneralOptsForMemorySanitizer. EarlyCSEPass makes visible
            // difference on size. It's not clear if the rest is still
            // usefull. InstCombinePass breakes
            // compiler-rt/test/msan/select_origin.cpp.
          }
          MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
        }
      };
      MSanPass(SanitizerKind::Memory, false);
      MSanPass(SanitizerKind::KernelMemory, true);
  
      if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
        MPM.addPass(ModuleThreadSanitizerPass());
        MPM.addPass(createModuleToFunctionPassAdaptor(ThreadSanitizerPass()));
      }
  
      auto ASanPass = [&](SanitizerMask Mask, bool CompileKernel) {
        if (LangOpts.Sanitize.has(Mask)) {
          bool Recover = CodeGenOpts.SanitizeRecover.has(Mask);
          bool UseAfterScope = CodeGenOpts.SanitizeAddressUseAfterScope;
          bool ModuleUseAfterScope = asanUseGlobalsGC(TargetTriple, CodeGenOpts);
          bool UseOdrIndicator = CodeGenOpts.SanitizeAddressUseOdrIndicator;
          llvm::AsanDtorKind DestructorKind =
              CodeGenOpts.getSanitizeAddressDtor();
          llvm::AsanDetectStackUseAfterReturnMode UseAfterReturn =
              CodeGenOpts.getSanitizeAddressUseAfterReturn();
          MPM.addPass(RequireAnalysisPass<ASanGlobalsMetadataAnalysis, Module>());
          MPM.addPass(ModuleAddressSanitizerPass(
              CompileKernel, Recover, ModuleUseAfterScope, UseOdrIndicator,
              DestructorKind));
          MPM.addPass(createModuleToFunctionPassAdaptor(AddressSanitizerPass(
              {CompileKernel, Recover, UseAfterScope, UseAfterReturn})));
        }
      };
      ASanPass(SanitizerKind::Address, false);
      ASanPass(SanitizerKind::KernelAddress, true);
  
      auto HWASanPass = [&](SanitizerMask Mask, bool CompileKernel) {
        if (LangOpts.Sanitize.has(Mask)) {
          bool Recover = CodeGenOpts.SanitizeRecover.has(Mask);
          MPM.addPass(HWAddressSanitizerPass(
              {CompileKernel, Recover,
               /*DisableOptimization=*/CodeGenOpts.OptimizationLevel == 0}));
        }
      };
      HWASanPass(SanitizerKind::HWAddress, false);
      HWASanPass(SanitizerKind::KernelHWAddress, true);
  
      if (LangOpts.Sanitize.has(SanitizerKind::DataFlow)) {
        MPM.addPass(DataFlowSanitizerPass(LangOpts.NoSanitizeFiles));
      }
    });
  }
  
  void EmitAssemblyHelper::RunOptimizationPipeline(
      BackendAction Action, std::unique_ptr<raw_pwrite_stream> &OS,
      std::unique_ptr<llvm::ToolOutputFile> &ThinLinkOS) {
    Optional<PGOOptions> PGOOpt;
  
    if (CodeGenOpts.hasProfileIRInstr())
      // -fprofile-generate.
      PGOOpt = PGOOptions(CodeGenOpts.InstrProfileOutput.empty()
                              ? std::string(DefaultProfileGenName)
                              : CodeGenOpts.InstrProfileOutput,
                          "", "", PGOOptions::IRInstr, PGOOptions::NoCSAction,
                          CodeGenOpts.DebugInfoForProfiling);
    else if (CodeGenOpts.hasProfileIRUse()) {
      // -fprofile-use.
      auto CSAction = CodeGenOpts.hasProfileCSIRUse() ? PGOOptions::CSIRUse
                                                      : PGOOptions::NoCSAction;
      PGOOpt = PGOOptions(CodeGenOpts.ProfileInstrumentUsePath, "",
                          CodeGenOpts.ProfileRemappingFile, PGOOptions::IRUse,
                          CSAction, CodeGenOpts.DebugInfoForProfiling);
    } else if (!CodeGenOpts.SampleProfileFile.empty())
      // -fprofile-sample-use
      PGOOpt = PGOOptions(
          CodeGenOpts.SampleProfileFile, "", CodeGenOpts.ProfileRemappingFile,
          PGOOptions::SampleUse, PGOOptions::NoCSAction,
          CodeGenOpts.DebugInfoForProfiling, CodeGenOpts.PseudoProbeForProfiling);
    else if (CodeGenOpts.PseudoProbeForProfiling)
      // -fpseudo-probe-for-profiling
      PGOOpt =
          PGOOptions("", "", "", PGOOptions::NoAction, PGOOptions::NoCSAction,
                     CodeGenOpts.DebugInfoForProfiling, true);
    else if (CodeGenOpts.DebugInfoForProfiling)
      // -fdebug-info-for-profiling
      PGOOpt = PGOOptions("", "", "", PGOOptions::NoAction,
                          PGOOptions::NoCSAction, true);
  
    // Check to see if we want to generate a CS profile.
    if (CodeGenOpts.hasProfileCSIRInstr()) {
      assert(!CodeGenOpts.hasProfileCSIRUse() &&
             "Cannot have both CSProfileUse pass and CSProfileGen pass at "
             "the same time");
      if (PGOOpt.hasValue()) {
        assert(PGOOpt->Action != PGOOptions::IRInstr &&
               PGOOpt->Action != PGOOptions::SampleUse &&
               "Cannot run CSProfileGen pass with ProfileGen or SampleUse "
               " pass");
        PGOOpt->CSProfileGenFile = CodeGenOpts.InstrProfileOutput.empty()
                                       ? std::string(DefaultProfileGenName)
                                       : CodeGenOpts.InstrProfileOutput;
        PGOOpt->CSAction = PGOOptions::CSIRInstr;
      } else
        PGOOpt = PGOOptions("",
                            CodeGenOpts.InstrProfileOutput.empty()
                                ? std::string(DefaultProfileGenName)
                                : CodeGenOpts.InstrProfileOutput,
                            "", PGOOptions::NoAction, PGOOptions::CSIRInstr,
                            CodeGenOpts.DebugInfoForProfiling);
    }
    if (TM)
      TM->setPGOOption(PGOOpt);
  
    PipelineTuningOptions PTO;
    PTO.LoopUnrolling = CodeGenOpts.UnrollLoops;
    // For historical reasons, loop interleaving is set to mirror setting for loop
    // unrolling.
    PTO.LoopInterleaving = CodeGenOpts.UnrollLoops;
    PTO.LoopVectorization = CodeGenOpts.VectorizeLoop;
    PTO.SLPVectorization = CodeGenOpts.VectorizeSLP;
    PTO.MergeFunctions = CodeGenOpts.MergeFunctions;
    // Only enable CGProfilePass when using integrated assembler, since
    // non-integrated assemblers don't recognize .cgprofile section.
    PTO.CallGraphProfile = !CodeGenOpts.DisableIntegratedAS;
  
    LoopAnalysisManager LAM;
    FunctionAnalysisManager FAM;
    CGSCCAnalysisManager CGAM;
    ModuleAnalysisManager MAM;
  
    bool DebugPassStructure = CodeGenOpts.DebugPass == "Structure";
    PassInstrumentationCallbacks PIC;
    PrintPassOptions PrintPassOpts;
    PrintPassOpts.Indent = DebugPassStructure;
    PrintPassOpts.SkipAnalyses = DebugPassStructure;
    StandardInstrumentations SI(CodeGenOpts.DebugPassManager ||
                                    DebugPassStructure,
                                /*VerifyEach*/ false, PrintPassOpts);
    SI.registerCallbacks(PIC, &FAM);
    PassBuilder PB(TM.get(), PTO, PGOOpt, &PIC);
  
    // Attempt to load pass plugins and register their callbacks with PB.
    for (auto &PluginFN : CodeGenOpts.PassPlugins) {
      auto PassPlugin = PassPlugin::Load(PluginFN);
      if (PassPlugin) {
        PassPlugin->registerPassBuilderCallbacks(PB);
      } else {
        Diags.Report(diag::err_fe_unable_to_load_plugin)
            << PluginFN << toString(PassPlugin.takeError());
      }
    }
  #define HANDLE_EXTENSION(Ext)                                                  \
    get##Ext##PluginInfo().RegisterPassBuilderCallbacks(PB);
  #include "llvm/Support/Extension.def"
  
    // Register the AA manager first so that our version is the one used.
    FAM.registerPass([&] { return PB.buildDefaultAAPipeline(); });
  
    // Register the target library analysis directly and give it a customized
    // preset TLI.
    Triple TargetTriple(TheModule->getTargetTriple());
    std::unique_ptr<TargetLibraryInfoImpl> TLII(
        createTLII(TargetTriple, CodeGenOpts));
    FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
  
    // Register all the basic analyses with the managers.
    PB.registerModuleAnalyses(MAM);
    PB.registerCGSCCAnalyses(CGAM);
    PB.registerFunctionAnalyses(FAM);
    PB.registerLoopAnalyses(LAM);
    PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
  
    ModulePassManager MPM;
  
    if (!CodeGenOpts.DisableLLVMPasses) {
      // Map our optimization levels into one of the distinct levels used to
      // configure the pipeline.
      OptimizationLevel Level = mapToLevel(CodeGenOpts);
  
      bool IsThinLTO = CodeGenOpts.PrepareForThinLTO;
      bool IsLTO = CodeGenOpts.PrepareForLTO;
  
      if (LangOpts.ObjCAutoRefCount) {
        PB.registerPipelineStartEPCallback(
            [](ModulePassManager &MPM, OptimizationLevel Level) {
              if (Level != OptimizationLevel::O0)
                MPM.addPass(
                    createModuleToFunctionPassAdaptor(ObjCARCExpandPass()));
            });
        PB.registerPipelineEarlySimplificationEPCallback(
            [](ModulePassManager &MPM, OptimizationLevel Level) {
              if (Level != OptimizationLevel::O0)
                MPM.addPass(ObjCARCAPElimPass());
            });
        PB.registerScalarOptimizerLateEPCallback(
            [](FunctionPassManager &FPM, OptimizationLevel Level) {
              if (Level != OptimizationLevel::O0)
                FPM.addPass(ObjCARCOptPass());
            });
      }
  
      // If we reached here with a non-empty index file name, then the index
      // file was empty and we are not performing ThinLTO backend compilation
      // (used in testing in a distributed build environment).
      bool IsThinLTOPostLink = !CodeGenOpts.ThinLTOIndexFile.empty();
      // If so drop any the type test assume sequences inserted for whole program
      // vtables so that codegen doesn't complain.
      if (IsThinLTOPostLink)
        PB.registerPipelineStartEPCallback(
            [](ModulePassManager &MPM, OptimizationLevel Level) {
              MPM.addPass(LowerTypeTestsPass(/*ExportSummary=*/nullptr,
                                             /*ImportSummary=*/nullptr,
                                             /*DropTypeTests=*/true));
            });
  
      if (CodeGenOpts.InstrumentFunctions ||
          CodeGenOpts.InstrumentFunctionEntryBare ||
          CodeGenOpts.InstrumentFunctionsAfterInlining ||
          CodeGenOpts.InstrumentForProfiling) {
        PB.registerPipelineStartEPCallback(
            [](ModulePassManager &MPM, OptimizationLevel Level) {
              MPM.addPass(createModuleToFunctionPassAdaptor(
                  EntryExitInstrumenterPass(/*PostInlining=*/false)));
            });
        PB.registerOptimizerLastEPCallback(
            [](ModulePassManager &MPM, OptimizationLevel Level) {
              MPM.addPass(createModuleToFunctionPassAdaptor(
                  EntryExitInstrumenterPass(/*PostInlining=*/true)));
            });
      }
  
      // Register callbacks to schedule sanitizer passes at the appropriate part
      // of the pipeline.
      if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
        PB.registerScalarOptimizerLateEPCallback(
            [](FunctionPassManager &FPM, OptimizationLevel Level) {
              FPM.addPass(BoundsCheckingPass());
            });
  
      // Don't add sanitizers if we are here from ThinLTO PostLink. That already
      // done on PreLink stage.
      if (!IsThinLTOPostLink)
        addSanitizers(TargetTriple, CodeGenOpts, LangOpts, PB);
  
      if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts, LangOpts))
        PB.registerPipelineStartEPCallback(
            [Options](ModulePassManager &MPM, OptimizationLevel Level) {
              MPM.addPass(GCOVProfilerPass(*Options));
            });
      if (Optional<InstrProfOptions> Options =
              getInstrProfOptions(CodeGenOpts, LangOpts))
        PB.registerPipelineStartEPCallback(
            [Options](ModulePassManager &MPM, OptimizationLevel Level) {
              MPM.addPass(InstrProfiling(*Options, false));
            });
  
      if (CodeGenOpts.OptimizationLevel == 0) {
        MPM = PB.buildO0DefaultPipeline(Level, IsLTO || IsThinLTO);
      } else if (IsThinLTO) {
        MPM = PB.buildThinLTOPreLinkDefaultPipeline(Level);
      } else if (IsLTO) {
        MPM = PB.buildLTOPreLinkDefaultPipeline(Level);
      } else {
        MPM = PB.buildPerModuleDefaultPipeline(Level);
      }
  
      if (!CodeGenOpts.MemoryProfileOutput.empty()) {
        MPM.addPass(createModuleToFunctionPassAdaptor(MemProfilerPass()));
        MPM.addPass(ModuleMemProfilerPass());
      }
    }
    switch (Action) {
    case Backend_EmitBC:
      if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
        if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
          ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
          if (!ThinLinkOS)
            return;
        }
        TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
                                 CodeGenOpts.EnableSplitLTOUnit);
        MPM.addPass(ThinLTOBitcodeWriterPass(*OS, ThinLinkOS ? &ThinLinkOS->os()
                                                             : nullptr));
      } else {
        // Emit a module summary by default for Regular LTO except for ld64
        // targets
        bool EmitLTOSummary =
            (CodeGenOpts.PrepareForLTO && !CodeGenOpts.DisableLLVMPasses &&
             llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
                 llvm::Triple::Apple);
        if (EmitLTOSummary) {
          if (!TheModule->getModuleFlag("ThinLTO"))
            TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
          TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
                                   uint32_t(1));
        }
        MPM.addPass(
            BitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
      }
      break;
  
    case Backend_EmitLL:
      MPM.addPass(PrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
      break;
  
    default:
      break;
    }
  
    // Now that we have all of the passes ready, run them.
    PrettyStackTraceString CrashInfo("Optimizer");
    MPM.run(*TheModule, MAM);
  }
  
  void EmitAssemblyHelper::RunCodegenPipeline(
      BackendAction Action, std::unique_ptr<raw_pwrite_stream> &OS,
      std::unique_ptr<llvm::ToolOutputFile> &DwoOS) {
    // We still use the legacy PM to run the codegen pipeline since the new PM
    // does not work with the codegen pipeline.
    // FIXME: make the new PM work with the codegen pipeline.
    legacy::PassManager CodeGenPasses;
  
    // Append any output we need to the pass manager.
    switch (Action) {
    case Backend_EmitAssembly:
    case Backend_EmitMCNull:
    case Backend_EmitObj:
      CodeGenPasses.add(
          createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
      if (!CodeGenOpts.SplitDwarfOutput.empty()) {
        DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
        if (!DwoOS)
          return;
      }
      if (!AddEmitPasses(CodeGenPasses, Action, *OS,
                         DwoOS ? &DwoOS->os() : nullptr))
        // FIXME: Should we handle this error differently?
        return;
      break;
    default:
      return;
    }
  
    PrettyStackTraceString CrashInfo("Code generation");
    CodeGenPasses.run(*TheModule);
  }
  
  /// A clean version of `EmitAssembly` that uses the new pass manager.
  ///
  /// Not all features are currently supported in this system, but where
  /// necessary it falls back to the legacy pass manager to at least provide
  /// basic functionality.
  ///
  /// This API is planned to have its functionality finished and then to replace
  /// `EmitAssembly` at some point in the future when the default switches.
  void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
                                        std::unique_ptr<raw_pwrite_stream> OS) {
    TimeRegion Region(CodeGenOpts.TimePasses ? &CodeGenerationTime : nullptr);
    setCommandLineOpts(CodeGenOpts);
  
    bool RequiresCodeGen = (Action != Backend_EmitNothing &&
                            Action != Backend_EmitBC && Action != Backend_EmitLL);
    CreateTargetMachine(RequiresCodeGen);
  
    if (RequiresCodeGen && !TM)
      return;
    if (TM)
      TheModule->setDataLayout(TM->createDataLayout());
  
    // Before executing passes, print the final values of the LLVM options.
    cl::PrintOptionValues();
  
    std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
    RunOptimizationPipeline(Action, OS, ThinLinkOS);
    RunCodegenPipeline(Action, OS, DwoOS);
  
    if (ThinLinkOS)
      ThinLinkOS->keep();
    if (DwoOS)
      DwoOS->keep();
  }
  
  static void runThinLTOBackend(
      DiagnosticsEngine &Diags, ModuleSummaryIndex *CombinedIndex, Module *M,
      const HeaderSearchOptions &HeaderOpts, const CodeGenOptions &CGOpts,
      const clang::TargetOptions &TOpts, const LangOptions &LOpts,
      std::unique_ptr<raw_pwrite_stream> OS, std::string SampleProfile,
      std::string ProfileRemapping, BackendAction Action) {
    StringMap<DenseMap<GlobalValue::GUID, GlobalValueSummary *>>
        ModuleToDefinedGVSummaries;
    CombinedIndex->collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
  
    setCommandLineOpts(CGOpts);
  
    // We can simply import the values mentioned in the combined index, since
    // we should only invoke this using the individual indexes written out
    // via a WriteIndexesThinBackend.
    FunctionImporter::ImportMapTy ImportList;
    if (!lto::initImportList(*M, *CombinedIndex, ImportList))
      return;
  
    auto AddStream = [&](size_t Task) {
      return std::make_unique<NativeObjectStream>(std::move(OS));
    };
    lto::Config Conf;
    if (CGOpts.SaveTempsFilePrefix != "") {
      if (Error E = Conf.addSaveTemps(CGOpts.SaveTempsFilePrefix + ".",
                                      /* UseInputModulePath */ false)) {
        handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
          errs() << "Error setting up ThinLTO save-temps: " << EIB.message()
                 << '\n';
        });
      }
    }
    Conf.CPU = TOpts.CPU;
    Conf.CodeModel = getCodeModel(CGOpts);
    Conf.MAttrs = TOpts.Features;
    Conf.RelocModel = CGOpts.RelocationModel;
    Conf.CGOptLevel = getCGOptLevel(CGOpts);
    Conf.OptLevel = CGOpts.OptimizationLevel;
    initTargetOptions(Diags, Conf.Options, CGOpts, TOpts, LOpts, HeaderOpts);
    Conf.SampleProfile = std::move(SampleProfile);
    Conf.PTO.LoopUnrolling = CGOpts.UnrollLoops;
    // For historical reasons, loop interleaving is set to mirror setting for loop
    // unrolling.
    Conf.PTO.LoopInterleaving = CGOpts.UnrollLoops;
    Conf.PTO.LoopVectorization = CGOpts.VectorizeLoop;
    Conf.PTO.SLPVectorization = CGOpts.VectorizeSLP;
    // Only enable CGProfilePass when using integrated assembler, since
    // non-integrated assemblers don't recognize .cgprofile section.
    Conf.PTO.CallGraphProfile = !CGOpts.DisableIntegratedAS;
  
    // Context sensitive profile.
    if (CGOpts.hasProfileCSIRInstr()) {
      Conf.RunCSIRInstr = true;
      Conf.CSIRProfile = std::move(CGOpts.InstrProfileOutput);
    } else if (CGOpts.hasProfileCSIRUse()) {
      Conf.RunCSIRInstr = false;
      Conf.CSIRProfile = std::move(CGOpts.ProfileInstrumentUsePath);
    }
  
    Conf.ProfileRemapping = std::move(ProfileRemapping);
    Conf.UseNewPM = !CGOpts.LegacyPassManager;
    Conf.DebugPassManager = CGOpts.DebugPassManager;
    Conf.RemarksWithHotness = CGOpts.DiagnosticsWithHotness;
    Conf.RemarksFilename = CGOpts.OptRecordFile;
    Conf.RemarksPasses = CGOpts.OptRecordPasses;
    Conf.RemarksFormat = CGOpts.OptRecordFormat;
    Conf.SplitDwarfFile = CGOpts.SplitDwarfFile;
    Conf.SplitDwarfOutput = CGOpts.SplitDwarfOutput;
    switch (Action) {
    case Backend_EmitNothing:
      Conf.PreCodeGenModuleHook = [](size_t Task, const Module &Mod) {
        return false;
      };
      break;
    case Backend_EmitLL:
      Conf.PreCodeGenModuleHook = [&](size_t Task, const Module &Mod) {
        M->print(*OS, nullptr, CGOpts.EmitLLVMUseLists);
        return false;
      };
      break;
    case Backend_EmitBC:
      Conf.PreCodeGenModuleHook = [&](size_t Task, const Module &Mod) {
        WriteBitcodeToFile(*M, *OS, CGOpts.EmitLLVMUseLists);
        return false;
      };
      break;
    default:
      Conf.CGFileType = getCodeGenFileType(Action);
      break;
    }
    if (Error E =
            thinBackend(Conf, -1, AddStream, *M, *CombinedIndex, ImportList,
                        ModuleToDefinedGVSummaries[M->getModuleIdentifier()],
                        /* ModuleMap */ nullptr, CGOpts.CmdArgs)) {
      handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
        errs() << "Error running ThinLTO backend: " << EIB.message() << '\n';
      });
    }
  }
  
  void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
                                const HeaderSearchOptions &HeaderOpts,
                                const CodeGenOptions &CGOpts,
                                const clang::TargetOptions &TOpts,
                                const LangOptions &LOpts,
                                StringRef TDesc, Module *M,
                                BackendAction Action,
                                std::unique_ptr<raw_pwrite_stream> OS) {
  
    llvm::TimeTraceScope TimeScope("Backend");
  
    std::unique_ptr<llvm::Module> EmptyModule;
    if (!CGOpts.ThinLTOIndexFile.empty()) {
      // If we are performing a ThinLTO importing compile, load the function index
      // into memory and pass it into runThinLTOBackend, which will run the
      // function importer and invoke LTO passes.
      std::unique_ptr<ModuleSummaryIndex> CombinedIndex;
      if (Error E = llvm::getModuleSummaryIndexForFile(
                        CGOpts.ThinLTOIndexFile,
                        /*IgnoreEmptyThinLTOIndexFile*/ true)
                        .moveInto(CombinedIndex)) {
        logAllUnhandledErrors(std::move(E), errs(),
                              "Error loading index file '" +
                              CGOpts.ThinLTOIndexFile + "': ");
        return;
      }
  
      // A null CombinedIndex means we should skip ThinLTO compilation
      // (LLVM will optionally ignore empty index files, returning null instead
      // of an error).
      if (CombinedIndex) {
        if (!CombinedIndex->skipModuleByDistributedBackend()) {
          runThinLTOBackend(Diags, CombinedIndex.get(), M, HeaderOpts, CGOpts,
                            TOpts, LOpts, std::move(OS), CGOpts.SampleProfileFile,
                            CGOpts.ProfileRemappingFile, Action);
          return;
        }
        // Distributed indexing detected that nothing from the module is needed
        // for the final linking. So we can skip the compilation. We sill need to
        // output an empty object file to make sure that a linker does not fail
        // trying to read it. Also for some features, like CFI, we must skip
        // the compilation as CombinedIndex does not contain all required
        // information.
        EmptyModule = std::make_unique<llvm::Module>("empty", M->getContext());
        EmptyModule->setTargetTriple(M->getTargetTriple());
        M = EmptyModule.get();
      }
    }
  
    EmitAssemblyHelper AsmHelper(Diags, HeaderOpts, CGOpts, TOpts, LOpts, M);
  
    if (CGOpts.LegacyPassManager)
      AsmHelper.EmitAssemblyWithLegacyPassManager(Action, std::move(OS));
    else
      AsmHelper.EmitAssembly(Action, std::move(OS));
  
    // Verify clang's TargetInfo DataLayout against the LLVM TargetMachine's
    // DataLayout.
    if (AsmHelper.TM) {
      std::string DLDesc = M->getDataLayout().getStringRepresentation();
      if (DLDesc != TDesc) {
        unsigned DiagID = Diags.getCustomDiagID(
            DiagnosticsEngine::Error, "backend data layout '%0' does not match "
                                      "expected target description '%1'");
        Diags.Report(DiagID) << DLDesc << TDesc;
      }
    }
  }
  
  // With -fembed-bitcode, save a copy of the llvm IR as data in the
  // __LLVM,__bitcode section.
  void clang::EmbedBitcode(llvm::Module *M, const CodeGenOptions &CGOpts,
                           llvm::MemoryBufferRef Buf) {
    if (CGOpts.getEmbedBitcode() == CodeGenOptions::Embed_Off)
      return;
    llvm::EmbedBitcodeInModule(
        *M, Buf, CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Marker,
        CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Bitcode,
        CGOpts.CmdArgs);
  }
  