PassWrapper.cpp

#include "LLVMWrapper.h"

#include "llvm-c/Core.h"
#include "llvm/Analysis/Lint.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Bitcode/BitcodeWriter.h"
#include "llvm/CodeGen/CommandFlags.h"
#include "llvm/IR/AssemblyAnnotationWriter.h"
#include "llvm/IR/AutoUpgrade.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Verifier.h"
#include "llvm/LTO/LTO.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/Passes/PassPlugin.h"
#include "llvm/Passes/StandardInstrumentations.h"
#include "llvm/Support/CBindingWrapping.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/TargetParser/Host.h"
#include "llvm/Transforms/IPO/FunctionImport.h"
#include "llvm/Transforms/IPO/Internalize.h"
#include "llvm/Transforms/IPO/LowerTypeTests.h"
#include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
#include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
#include "llvm/Transforms/Instrumentation/DataFlowSanitizer.h"
#include "llvm/Transforms/Instrumentation/HWAddressSanitizer.h"
#include "llvm/Transforms/Instrumentation/InstrProfiling.h"
#include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
#include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
#include "llvm/Transforms/Utils/CanonicalizeAliases.h"
#include "llvm/Transforms/Utils/FunctionImportUtils.h"
#include "llvm/Transforms/Utils/NameAnonGlobals.h"
#include <set>
#include <vector>

#if LLVM_VERSION_GE(19, 0)
#include "llvm/Support/PGOOptions.h"
#endif

using namespace llvm;

static codegen::RegisterCodeGenFlags CGF;

typedef struct LLVMOpaquePass *LLVMPassRef;
typedef struct LLVMOpaqueTargetMachine *LLVMTargetMachineRef;

DEFINE_STDCXX_CONVERSION_FUNCTIONS(Pass, LLVMPassRef)
DEFINE_STDCXX_CONVERSION_FUNCTIONS(TargetMachine, LLVMTargetMachineRef)

extern "C" void LLVMRustTimeTraceProfilerInitialize() {
  timeTraceProfilerInitialize(
      /* TimeTraceGranularity */ 0,
      /* ProcName */ "rustc");
}

extern "C" void LLVMRustTimeTraceProfilerFinishThread() {
  timeTraceProfilerFinishThread();
}

extern "C" void LLVMRustTimeTraceProfilerFinish(const char *FileName) {
  auto FN = StringRef(FileName);
  std::error_code EC;
  auto OS = raw_fd_ostream(FN, EC, sys::fs::CD_CreateAlways);

  timeTraceProfilerWrite(OS);
  timeTraceProfilerCleanup();
}

#ifdef LLVM_COMPONENT_X86
#define SUBTARGET_X86 SUBTARGET(X86)
#else
#define SUBTARGET_X86
#endif

#ifdef LLVM_COMPONENT_ARM
#define SUBTARGET_ARM SUBTARGET(ARM)
#else
#define SUBTARGET_ARM
#endif

#ifdef LLVM_COMPONENT_AARCH64
#define SUBTARGET_AARCH64 SUBTARGET(AArch64)
#else
#define SUBTARGET_AARCH64
#endif

#ifdef LLVM_COMPONENT_AVR
#define SUBTARGET_AVR SUBTARGET(AVR)
#else
#define SUBTARGET_AVR
#endif

#ifdef LLVM_COMPONENT_M68k
#define SUBTARGET_M68K SUBTARGET(M68k)
#else
#define SUBTARGET_M68K
#endif

#ifdef LLVM_COMPONENT_CSKY
#define SUBTARGET_CSKY SUBTARGET(CSKY)
#else
#define SUBTARGET_CSKY
#endif

#ifdef LLVM_COMPONENT_MIPS
#define SUBTARGET_MIPS SUBTARGET(Mips)
#else
#define SUBTARGET_MIPS
#endif

#ifdef LLVM_COMPONENT_POWERPC
#define SUBTARGET_PPC SUBTARGET(PPC)
#else
#define SUBTARGET_PPC
#endif

#ifdef LLVM_COMPONENT_SYSTEMZ
#define SUBTARGET_SYSTEMZ SUBTARGET(SystemZ)
#else
#define SUBTARGET_SYSTEMZ
#endif

#ifdef LLVM_COMPONENT_MSP430
#define SUBTARGET_MSP430 SUBTARGET(MSP430)
#else
#define SUBTARGET_MSP430
#endif

#ifdef LLVM_COMPONENT_RISCV
#define SUBTARGET_RISCV SUBTARGET(RISCV)
#else
#define SUBTARGET_RISCV
#endif

#ifdef LLVM_COMPONENT_SPARC
#define SUBTARGET_SPARC SUBTARGET(Sparc)
#else
#define SUBTARGET_SPARC
#endif

#ifdef LLVM_COMPONENT_XTENSA
#define SUBTARGET_XTENSA SUBTARGET(XTENSA)
#else
#define SUBTARGET_XTENSA
#endif

#ifdef LLVM_COMPONENT_HEXAGON
#define SUBTARGET_HEXAGON SUBTARGET(Hexagon)
#else
#define SUBTARGET_HEXAGON
#endif

#ifdef LLVM_COMPONENT_LOONGARCH
#define SUBTARGET_LOONGARCH SUBTARGET(LoongArch)
#else
#define SUBTARGET_LOONGARCH
#endif

#define GEN_SUBTARGETS                                                         \
  SUBTARGET_X86                                                                \
  SUBTARGET_ARM                                                                \
  SUBTARGET_AARCH64                                                            \
  SUBTARGET_AVR                                                                \
  SUBTARGET_M68K                                                               \
  SUBTARGET_CSKY                                                               \
  SUBTARGET_MIPS                                                               \
  SUBTARGET_PPC                                                                \
  SUBTARGET_SYSTEMZ                                                            \
  SUBTARGET_MSP430                                                             \
  SUBTARGET_SPARC                                                              \
  SUBTARGET_HEXAGON                                                            \
  SUBTARGET_XTENSA                                                             \
  SUBTARGET_RISCV                                                              \
  SUBTARGET_LOONGARCH

#define SUBTARGET(x)                                                           \
  namespace llvm {                                                             \
  extern const SubtargetFeatureKV x##FeatureKV[];                              \
  extern const SubtargetFeatureKV x##SubTypeKV[];                              \
  }

GEN_SUBTARGETS
#undef SUBTARGET

extern "C" bool LLVMRustHasFeature(LLVMTargetMachineRef TM,
                                   const char *Feature) {
  TargetMachine *Target = unwrap(TM);
  const MCSubtargetInfo *MCInfo = Target->getMCSubtargetInfo();
  return MCInfo->checkFeatures(std::string("+") + Feature);
}

enum class LLVMRustCodeModel {
  Tiny,
  Small,
  Kernel,
  Medium,
  Large,
  None,
};

static std::optional<CodeModel::Model> fromRust(LLVMRustCodeModel Model) {
  switch (Model) {
  case LLVMRustCodeModel::Tiny:
    return CodeModel::Tiny;
  case LLVMRustCodeModel::Small:
    return CodeModel::Small;
  case LLVMRustCodeModel::Kernel:
    return CodeModel::Kernel;
  case LLVMRustCodeModel::Medium:
    return CodeModel::Medium;
  case LLVMRustCodeModel::Large:
    return CodeModel::Large;
  case LLVMRustCodeModel::None:
    return std::nullopt;
  default:
    report_fatal_error("Bad CodeModel.");
  }
}

enum class LLVMRustCodeGenOptLevel {
  None,
  Less,
  Default,
  Aggressive,
};

using CodeGenOptLevelEnum = llvm::CodeGenOptLevel;

static CodeGenOptLevelEnum fromRust(LLVMRustCodeGenOptLevel Level) {
  switch (Level) {
  case LLVMRustCodeGenOptLevel::None:
    return CodeGenOptLevelEnum::None;
  case LLVMRustCodeGenOptLevel::Less:
    return CodeGenOptLevelEnum::Less;
  case LLVMRustCodeGenOptLevel::Default:
    return CodeGenOptLevelEnum::Default;
  case LLVMRustCodeGenOptLevel::Aggressive:
    return CodeGenOptLevelEnum::Aggressive;
  default:
    report_fatal_error("Bad CodeGenOptLevel.");
  }
}

enum class LLVMRustPassBuilderOptLevel {
  O0,
  O1,
  O2,
  O3,
  Os,
  Oz,
};

static OptimizationLevel fromRust(LLVMRustPassBuilderOptLevel Level) {
  switch (Level) {
  case LLVMRustPassBuilderOptLevel::O0:
    return OptimizationLevel::O0;
  case LLVMRustPassBuilderOptLevel::O1:
    return OptimizationLevel::O1;
  case LLVMRustPassBuilderOptLevel::O2:
    return OptimizationLevel::O2;
  case LLVMRustPassBuilderOptLevel::O3:
    return OptimizationLevel::O3;
  case LLVMRustPassBuilderOptLevel::Os:
    return OptimizationLevel::Os;
  case LLVMRustPassBuilderOptLevel::Oz:
    return OptimizationLevel::Oz;
  default:
    report_fatal_error("Bad PassBuilderOptLevel.");
  }
}

enum class LLVMRustRelocModel {
  Static,
  PIC,
  DynamicNoPic,
  ROPI,
  RWPI,
  ROPIRWPI,
};

static Reloc::Model fromRust(LLVMRustRelocModel RustReloc) {
  switch (RustReloc) {
  case LLVMRustRelocModel::Static:
    return Reloc::Static;
  case LLVMRustRelocModel::PIC:
    return Reloc::PIC_;
  case LLVMRustRelocModel::DynamicNoPic:
    return Reloc::DynamicNoPIC;
  case LLVMRustRelocModel::ROPI:
    return Reloc::ROPI;
  case LLVMRustRelocModel::RWPI:
    return Reloc::RWPI;
  case LLVMRustRelocModel::ROPIRWPI:
    return Reloc::ROPI_RWPI;
  }
  report_fatal_error("Bad RelocModel.");
}

/// getLongestEntryLength - Return the length of the longest entry in the table.
template <typename KV> static size_t getLongestEntryLength(ArrayRef<KV> Table) {
  size_t MaxLen = 0;
  for (auto &I : Table)
    MaxLen = std::max(MaxLen, std::strlen(I.Key));
  return MaxLen;
}

extern "C" void LLVMRustPrintTargetCPUs(LLVMTargetMachineRef TM,
                                        RustStringRef OutStr) {
  ArrayRef<SubtargetSubTypeKV> CPUTable =
      unwrap(TM)->getMCSubtargetInfo()->getAllProcessorDescriptions();
  auto OS = RawRustStringOstream(OutStr);

  // Just print a bare list of target CPU names, and let Rust-side code handle
  // the full formatting of `--print=target-cpus`.
  for (auto &CPU : CPUTable) {
    OS << CPU.Key << "\n";
  }
}

extern "C" size_t LLVMRustGetTargetFeaturesCount(LLVMTargetMachineRef TM) {
  const TargetMachine *Target = unwrap(TM);
  const MCSubtargetInfo *MCInfo = Target->getMCSubtargetInfo();
  const ArrayRef<SubtargetFeatureKV> FeatTable =
      MCInfo->getAllProcessorFeatures();
  return FeatTable.size();
}

extern "C" void LLVMRustGetTargetFeature(LLVMTargetMachineRef TM, size_t Index,
                                         const char **Feature,
                                         const char **Desc) {
  const TargetMachine *Target = unwrap(TM);
  const MCSubtargetInfo *MCInfo = Target->getMCSubtargetInfo();
  const ArrayRef<SubtargetFeatureKV> FeatTable =
      MCInfo->getAllProcessorFeatures();
  const SubtargetFeatureKV Feat = FeatTable[Index];
  *Feature = Feat.Key;
  *Desc = Feat.Desc;
}

extern "C" const char *LLVMRustGetHostCPUName(size_t *OutLen) {
  StringRef Name = sys::getHostCPUName();
  *OutLen = Name.size();
  return Name.data();
}

extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
    const char *TripleStr, const char *CPU, const char *Feature,
    const char *ABIStr, LLVMRustCodeModel RustCM, LLVMRustRelocModel RustReloc,
    LLVMRustCodeGenOptLevel RustOptLevel, bool UseSoftFloat,
    bool FunctionSections, bool DataSections, bool UniqueSectionNames,
    bool TrapUnreachable, bool Singlethread, bool VerboseAsm,
    bool EmitStackSizeSection, bool RelaxELFRelocations, bool UseInitArray,
    const char *SplitDwarfFile, const char *OutputObjFile,
    const char *DebugInfoCompression, bool UseEmulatedTls,
    const char *ArgsCstrBuff, size_t ArgsCstrBuffLen) {

  auto OptLevel = fromRust(RustOptLevel);
  auto RM = fromRust(RustReloc);
  auto CM = fromRust(RustCM);

  std::string Error;
  auto Trip = Triple(Triple::normalize(TripleStr));
  const llvm::Target *TheTarget =
      TargetRegistry::lookupTarget(Trip.getTriple(), Error);
  if (TheTarget == nullptr) {
    LLVMRustSetLastError(Error.c_str());
    return nullptr;
  }

  TargetOptions Options = codegen::InitTargetOptionsFromCodeGenFlags(Trip);

  Options.FloatABIType = FloatABI::Default;
  if (UseSoftFloat) {
    Options.FloatABIType = FloatABI::Soft;
  }
  Options.DataSections = DataSections;
  Options.FunctionSections = FunctionSections;
  Options.UniqueSectionNames = UniqueSectionNames;
  Options.MCOptions.AsmVerbose = VerboseAsm;
  // Always preserve comments that were written by the user
  Options.MCOptions.PreserveAsmComments = true;
  Options.MCOptions.ABIName = ABIStr;
  if (SplitDwarfFile) {
    Options.MCOptions.SplitDwarfFile = SplitDwarfFile;
  }
  if (OutputObjFile) {
    Options.ObjectFilenameForDebug = OutputObjFile;
  }
  if (!strcmp("zlib", DebugInfoCompression) &&
      llvm::compression::zlib::isAvailable()) {
#if LLVM_VERSION_GE(19, 0)
    Options.MCOptions.CompressDebugSections = DebugCompressionType::Zlib;
#else
    Options.CompressDebugSections = DebugCompressionType::Zlib;
#endif
  } else if (!strcmp("zstd", DebugInfoCompression) &&
             llvm::compression::zstd::isAvailable()) {
#if LLVM_VERSION_GE(19, 0)
    Options.MCOptions.CompressDebugSections = DebugCompressionType::Zstd;
#else
    Options.CompressDebugSections = DebugCompressionType::Zstd;
#endif
  } else if (!strcmp("none", DebugInfoCompression)) {
#if LLVM_VERSION_GE(19, 0)
    Options.MCOptions.CompressDebugSections = DebugCompressionType::None;
#else
    Options.CompressDebugSections = DebugCompressionType::None;
#endif
  }

#if LLVM_VERSION_GE(19, 0)
  Options.MCOptions.X86RelaxRelocations = RelaxELFRelocations;
#else
  Options.RelaxELFRelocations = RelaxELFRelocations;
#endif
  Options.UseInitArray = UseInitArray;
  Options.EmulatedTLS = UseEmulatedTls;

  if (TrapUnreachable) {
    // Tell LLVM to codegen `unreachable` into an explicit trap instruction.
    // This limits the extent of possible undefined behavior in some cases, as
    // it prevents control flow from "falling through" into whatever code
    // happens to be laid out next in memory.
    Options.TrapUnreachable = true;
    // But don't emit traps after other traps or no-returns unnecessarily.
    // ...except for when targeting WebAssembly, because the NoTrapAfterNoreturn
    // option causes bugs in the LLVM WebAssembly backend. You should be able to
    // remove this check when Rust's minimum supported LLVM version is >= 18
    // https://github.com/llvm/llvm-project/pull/65876
    if (!Trip.isWasm()) {
      Options.NoTrapAfterNoreturn = true;
    }
  }

  if (Singlethread) {
    Options.ThreadModel = ThreadModel::Single;
  }

  Options.EmitStackSizeSection = EmitStackSizeSection;

  if (ArgsCstrBuff != nullptr) {
#if LLVM_VERSION_GE(20, 0)
    int buffer_offset = 0;
    assert(ArgsCstrBuff[ArgsCstrBuffLen - 1] == '\0');
    auto Arg0 = std::string(ArgsCstrBuff);
    buffer_offset = Arg0.size() + 1;
    auto ArgsCppStr = std::string(ArgsCstrBuff + buffer_offset,
                                  ArgsCstrBuffLen - buffer_offset);
    auto i = 0;
    while (i != std::string::npos) {
      i = ArgsCppStr.find('\0', i + 1);
      if (i != std::string::npos)
        ArgsCppStr.replace(i, 1, " ");
    }
    Options.MCOptions.Argv0 = Arg0;
    Options.MCOptions.CommandlineArgs = ArgsCppStr;
#else
    int buffer_offset = 0;
    assert(ArgsCstrBuff[ArgsCstrBuffLen - 1] == '\0');

    const size_t arg0_len = std::strlen(ArgsCstrBuff);
    char *arg0 = new char[arg0_len + 1];
    memcpy(arg0, ArgsCstrBuff, arg0_len);
    arg0[arg0_len] = '\0';
    buffer_offset += arg0_len + 1;

    const int num_cmd_arg_strings = std::count(
        &ArgsCstrBuff[buffer_offset], &ArgsCstrBuff[ArgsCstrBuffLen], '\0');

    std::string *cmd_arg_strings = new std::string[num_cmd_arg_strings];
    for (int i = 0; i < num_cmd_arg_strings; ++i) {
      assert(buffer_offset < ArgsCstrBuffLen);
      const int len = std::strlen(ArgsCstrBuff + buffer_offset);
      cmd_arg_strings[i] = std::string(&ArgsCstrBuff[buffer_offset], len);
      buffer_offset += len + 1;
    }

    assert(buffer_offset == ArgsCstrBuffLen);

    Options.MCOptions.Argv0 = arg0;
    Options.MCOptions.CommandLineArgs =
        llvm::ArrayRef<std::string>(cmd_arg_strings, num_cmd_arg_strings);
#endif
  }

  TargetMachine *TM = TheTarget->createTargetMachine(
      Trip.getTriple(), CPU, Feature, Options, RM, CM, OptLevel);
  return wrap(TM);
}

extern "C" void LLVMRustDisposeTargetMachine(LLVMTargetMachineRef TM) {
#if LLVM_VERSION_LT(20, 0)
  MCTargetOptions &MCOptions = unwrap(TM)->Options.MCOptions;
  delete[] MCOptions.Argv0;
  delete[] MCOptions.CommandLineArgs.data();
#endif

  delete unwrap(TM);
}

// Unfortunately, the LLVM C API doesn't provide a way to create the
// TargetLibraryInfo pass, so we use this method to do so.
extern "C" void LLVMRustAddLibraryInfo(LLVMPassManagerRef PMR, LLVMModuleRef M,
                                       bool DisableSimplifyLibCalls) {
  auto TargetTriple = Triple(unwrap(M)->getTargetTriple());
  auto TLII = TargetLibraryInfoImpl(TargetTriple);
  if (DisableSimplifyLibCalls)
    TLII.disableAllFunctions();
  unwrap(PMR)->add(new TargetLibraryInfoWrapperPass(TLII));
}

extern "C" void LLVMRustSetLLVMOptions(int Argc, char **Argv) {
  // Initializing the command-line options more than once is not allowed. So,
  // check if they've already been initialized. (This could happen if we're
  // being called from rustpkg, for example). If the arguments change, then
  // that's just kinda unfortunate.
  static bool Initialized = false;
  if (Initialized)
    return;
  Initialized = true;
  cl::ParseCommandLineOptions(Argc, Argv);
}

enum class LLVMRustFileType {
  AssemblyFile,
  ObjectFile,
};

static CodeGenFileType fromRust(LLVMRustFileType Type) {
  switch (Type) {
  case LLVMRustFileType::AssemblyFile:
    return CodeGenFileType::AssemblyFile;
  case LLVMRustFileType::ObjectFile:
    return CodeGenFileType::ObjectFile;
  default:
    report_fatal_error("Bad FileType.");
  }
}

extern "C" LLVMRustResult
LLVMRustWriteOutputFile(LLVMTargetMachineRef Target, LLVMPassManagerRef PMR,
                        LLVMModuleRef M, const char *Path, const char *DwoPath,
                        LLVMRustFileType RustFileType) {
  llvm::legacy::PassManager *PM = unwrap<llvm::legacy::PassManager>(PMR);
  auto FileType = fromRust(RustFileType);

  std::string ErrorInfo;
  std::error_code EC;
  auto OS = raw_fd_ostream(Path, EC, sys::fs::OF_None);
  if (EC)
    ErrorInfo = EC.message();
  if (ErrorInfo != "") {
    LLVMRustSetLastError(ErrorInfo.c_str());
    return LLVMRustResult::Failure;
  }

  auto BOS = buffer_ostream(OS);
  if (DwoPath) {
    auto DOS = raw_fd_ostream(DwoPath, EC, sys::fs::OF_None);
    EC.clear();
    if (EC)
      ErrorInfo = EC.message();
    if (ErrorInfo != "") {
      LLVMRustSetLastError(ErrorInfo.c_str());
      return LLVMRustResult::Failure;
    }
    auto DBOS = buffer_ostream(DOS);
    unwrap(Target)->addPassesToEmitFile(*PM, BOS, &DBOS, FileType, false);
    PM->run(*unwrap(M));
  } else {
    unwrap(Target)->addPassesToEmitFile(*PM, BOS, nullptr, FileType, false);
    PM->run(*unwrap(M));
  }

  // Apparently `addPassesToEmitFile` adds a pointer to our on-the-stack output
  // stream (OS), so the only real safe place to delete this is here? Don't we
  // wish this was written in Rust?
  LLVMDisposePassManager(PMR);
  return LLVMRustResult::Success;
}

extern "C" typedef void (*LLVMRustSelfProfileBeforePassCallback)(
    void *,        // LlvmSelfProfiler
    const char *,  // pass name
    const char *); // IR name
extern "C" typedef void (*LLVMRustSelfProfileAfterPassCallback)(
    void *); // LlvmSelfProfiler

std::string LLVMRustwrappedIrGetName(const llvm::Any &WrappedIr) {
  if (const auto *Cast = any_cast<const Module *>(&WrappedIr))
    return (*Cast)->getName().str();
  if (const auto *Cast = any_cast<const Function *>(&WrappedIr))
    return (*Cast)->getName().str();
  if (const auto *Cast = any_cast<const Loop *>(&WrappedIr))
    return (*Cast)->getName().str();
  if (const auto *Cast = any_cast<const LazyCallGraph::SCC *>(&WrappedIr))
    return (*Cast)->getName();
  return "<UNKNOWN>";
}

void LLVMSelfProfileInitializeCallbacks(
    PassInstrumentationCallbacks &PIC, void *LlvmSelfProfiler,
    LLVMRustSelfProfileBeforePassCallback BeforePassCallback,
    LLVMRustSelfProfileAfterPassCallback AfterPassCallback) {
  PIC.registerBeforeNonSkippedPassCallback(
      [LlvmSelfProfiler, BeforePassCallback](StringRef Pass, llvm::Any Ir) {
        std::string PassName = Pass.str();
        std::string IrName = LLVMRustwrappedIrGetName(Ir);
        BeforePassCallback(LlvmSelfProfiler, PassName.c_str(), IrName.c_str());
      });

  PIC.registerAfterPassCallback(
      [LlvmSelfProfiler, AfterPassCallback](
          StringRef Pass, llvm::Any IR, const PreservedAnalyses &Preserved) {
        AfterPassCallback(LlvmSelfProfiler);
      });

  PIC.registerAfterPassInvalidatedCallback(
      [LlvmSelfProfiler,
       AfterPassCallback](StringRef Pass, const PreservedAnalyses &Preserved) {
        AfterPassCallback(LlvmSelfProfiler);
      });

  PIC.registerBeforeAnalysisCallback(
      [LlvmSelfProfiler, BeforePassCallback](StringRef Pass, llvm::Any Ir) {
        std::string PassName = Pass.str();
        std::string IrName = LLVMRustwrappedIrGetName(Ir);
        BeforePassCallback(LlvmSelfProfiler, PassName.c_str(), IrName.c_str());
      });

  PIC.registerAfterAnalysisCallback(
      [LlvmSelfProfiler, AfterPassCallback](StringRef Pass, llvm::Any Ir) {
        AfterPassCallback(LlvmSelfProfiler);
      });
}

enum class LLVMRustOptStage {
  PreLinkNoLTO,
  PreLinkThinLTO,
  PreLinkFatLTO,
  ThinLTO,
  FatLTO,
};

struct LLVMRustSanitizerOptions {
  bool SanitizeAddress;
  bool SanitizeAddressRecover;
  bool SanitizeCFI;
  bool SanitizeDataFlow;
  char **SanitizeDataFlowABIList;
  size_t SanitizeDataFlowABIListLen;
  bool SanitizeKCFI;
  bool SanitizeMemory;
  bool SanitizeMemoryRecover;
  int SanitizeMemoryTrackOrigins;
  bool SanitizeThread;
  bool SanitizeHWAddress;
  bool SanitizeHWAddressRecover;
  bool SanitizeKernelAddress;
  bool SanitizeKernelAddressRecover;
};

extern "C" LLVMRustResult LLVMRustOptimize(
    LLVMModuleRef ModuleRef, LLVMTargetMachineRef TMRef,
    LLVMRustPassBuilderOptLevel OptLevelRust, LLVMRustOptStage OptStage,
    bool IsLinkerPluginLTO, bool NoPrepopulatePasses, bool VerifyIR,
    bool LintIR, bool UseThinLTOBuffers, bool MergeFunctions, bool UnrollLoops,
    bool SLPVectorize, bool LoopVectorize, bool DisableSimplifyLibCalls,
    bool EmitLifetimeMarkers, LLVMRustSanitizerOptions *SanitizerOptions,
    const char *PGOGenPath, const char *PGOUsePath, bool InstrumentCoverage,
    const char *InstrProfileOutput, const char *PGOSampleUsePath,
    bool DebugInfoForProfiling, void *LlvmSelfProfiler,
    LLVMRustSelfProfileBeforePassCallback BeforePassCallback,
    LLVMRustSelfProfileAfterPassCallback AfterPassCallback,
    const char *ExtraPasses, size_t ExtraPassesLen, const char *LLVMPlugins,
    size_t LLVMPluginsLen) {
  Module *TheModule = unwrap(ModuleRef);
  TargetMachine *TM = unwrap(TMRef);
  OptimizationLevel OptLevel = fromRust(OptLevelRust);

  PipelineTuningOptions PTO;
  PTO.LoopUnrolling = UnrollLoops;
  PTO.LoopInterleaving = UnrollLoops;
  PTO.LoopVectorization = LoopVectorize;
  PTO.SLPVectorization = SLPVectorize;
  PTO.MergeFunctions = MergeFunctions;

  PassInstrumentationCallbacks PIC;

  if (LlvmSelfProfiler) {
    LLVMSelfProfileInitializeCallbacks(PIC, LlvmSelfProfiler,
                                       BeforePassCallback, AfterPassCallback);
  }

  std::optional<PGOOptions> PGOOpt;
  auto FS = vfs::getRealFileSystem();
  if (PGOGenPath) {
    assert(!PGOUsePath && !PGOSampleUsePath);
    PGOOpt = PGOOptions(PGOGenPath, "", "", "", FS, PGOOptions::IRInstr,
                        PGOOptions::NoCSAction,
#if LLVM_VERSION_GE(19, 0)
                        PGOOptions::ColdFuncOpt::Default,
#endif
                        DebugInfoForProfiling);
  } else if (PGOUsePath) {
    assert(!PGOSampleUsePath);
    PGOOpt = PGOOptions(PGOUsePath, "", "", "", FS, PGOOptions::IRUse,
                        PGOOptions::NoCSAction,
#if LLVM_VERSION_GE(19, 0)
                        PGOOptions::ColdFuncOpt::Default,
#endif
                        DebugInfoForProfiling);
  } else if (PGOSampleUsePath) {
    PGOOpt = PGOOptions(PGOSampleUsePath, "", "", "", FS, PGOOptions::SampleUse,
                        PGOOptions::NoCSAction,
#if LLVM_VERSION_GE(19, 0)
                        PGOOptions::ColdFuncOpt::Default,
#endif
                        DebugInfoForProfiling);
  } else if (DebugInfoForProfiling) {
    PGOOpt = PGOOptions("", "", "", "", FS, PGOOptions::NoAction,
                        PGOOptions::NoCSAction,
#if LLVM_VERSION_GE(19, 0)
                        PGOOptions::ColdFuncOpt::Default,
#endif
                        DebugInfoForProfiling);
  }

  auto PB = PassBuilder(TM, PTO, PGOOpt, &PIC);
  LoopAnalysisManager LAM;
  FunctionAnalysisManager FAM;
  CGSCCAnalysisManager CGAM;
  ModuleAnalysisManager MAM;

  StandardInstrumentations SI(TheModule->getContext(),
                              /*DebugLogging=*/false);
  SI.registerCallbacks(PIC, &MAM);

  if (LLVMPluginsLen) {
    auto PluginsStr = StringRef(LLVMPlugins, LLVMPluginsLen);
    SmallVector<StringRef> Plugins;
    PluginsStr.split(Plugins, ',', -1, false);
    for (auto PluginPath : Plugins) {
      auto Plugin = PassPlugin::Load(PluginPath.str());
      if (!Plugin) {
        auto Err = Plugin.takeError();
        auto ErrMsg = llvm::toString(std::move(Err));
        LLVMRustSetLastError(ErrMsg.c_str());
        return LLVMRustResult::Failure;
      }
      Plugin->registerPassBuilderCallbacks(PB);
    }
  }

  FAM.registerPass([&] { return PB.buildDefaultAAPipeline(); });

  Triple TargetTriple(TheModule->getTargetTriple());
  std::unique_ptr<TargetLibraryInfoImpl> TLII(
      new TargetLibraryInfoImpl(TargetTriple));
  if (DisableSimplifyLibCalls)
    TLII->disableAllFunctions();
  FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });

  PB.registerModuleAnalyses(MAM);
  PB.registerCGSCCAnalyses(CGAM);
  PB.registerFunctionAnalyses(FAM);
  PB.registerLoopAnalyses(LAM);
  PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);

  // We manually collect pipeline callbacks so we can apply them at O0, where
  // the PassBuilder does not create a pipeline.
  std::vector<std::function<void(ModulePassManager &, OptimizationLevel)>>
      PipelineStartEPCallbacks;
  std::vector<std::function<void(ModulePassManager &, OptimizationLevel)>>
      OptimizerLastEPCallbacks;

  if (!IsLinkerPluginLTO && SanitizerOptions && SanitizerOptions->SanitizeCFI &&
      !NoPrepopulatePasses) {
    PipelineStartEPCallbacks.push_back(
        [](ModulePassManager &MPM, OptimizationLevel Level) {
          MPM.addPass(LowerTypeTestsPass(
              /*ExportSummary=*/nullptr,
              /*ImportSummary=*/nullptr));
        });
  }

  if (VerifyIR) {
    PipelineStartEPCallbacks.push_back(
        [VerifyIR](ModulePassManager &MPM, OptimizationLevel Level) {
          MPM.addPass(VerifierPass());
        });
  }

  if (LintIR) {
    PipelineStartEPCallbacks.push_back(
        [](ModulePassManager &MPM, OptimizationLevel Level) {
          MPM.addPass(createModuleToFunctionPassAdaptor(LintPass()));
        });
  }

  if (InstrumentCoverage) {
    PipelineStartEPCallbacks.push_back(
        [InstrProfileOutput](ModulePassManager &MPM, OptimizationLevel Level) {
          InstrProfOptions Options;
          if (InstrProfileOutput) {
            Options.InstrProfileOutput = InstrProfileOutput;
          }
          // cargo run tests in multhreading mode by default
          // so use atomics for coverage counters
          Options.Atomic = true;
          MPM.addPass(InstrProfilingLoweringPass(Options, false));
        });
  }

  if (SanitizerOptions) {
    if (SanitizerOptions->SanitizeDataFlow) {
      std::vector<std::string> ABIListFiles(
          SanitizerOptions->SanitizeDataFlowABIList,
          SanitizerOptions->SanitizeDataFlowABIList +
              SanitizerOptions->SanitizeDataFlowABIListLen);
      OptimizerLastEPCallbacks.push_back(
          [ABIListFiles](ModulePassManager &MPM, OptimizationLevel Level) {
            MPM.addPass(DataFlowSanitizerPass(ABIListFiles));
          });
    }

    if (SanitizerOptions->SanitizeMemory) {
      MemorySanitizerOptions Options(
          SanitizerOptions->SanitizeMemoryTrackOrigins,
          SanitizerOptions->SanitizeMemoryRecover,
          /*CompileKernel=*/false,
          /*EagerChecks=*/true);
      OptimizerLastEPCallbacks.push_back(
          [Options](ModulePassManager &MPM, OptimizationLevel Level) {
            MPM.addPass(MemorySanitizerPass(Options));
          });
    }

    if (SanitizerOptions->SanitizeThread) {
      OptimizerLastEPCallbacks.push_back([](ModulePassManager &MPM,
                                            OptimizationLevel Level) {
        MPM.addPass(ModuleThreadSanitizerPass());
        MPM.addPass(createModuleToFunctionPassAdaptor(ThreadSanitizerPass()));
      });
    }

    if (SanitizerOptions->SanitizeAddress ||
        SanitizerOptions->SanitizeKernelAddress) {
      OptimizerLastEPCallbacks.push_back(
          [SanitizerOptions](ModulePassManager &MPM, OptimizationLevel Level) {
            auto CompileKernel = SanitizerOptions->SanitizeKernelAddress;
            AddressSanitizerOptions opts = AddressSanitizerOptions{
                CompileKernel,
                SanitizerOptions->SanitizeAddressRecover ||
                    SanitizerOptions->SanitizeKernelAddressRecover,
                /*UseAfterScope=*/true,
                AsanDetectStackUseAfterReturnMode::Runtime,
            };
            MPM.addPass(AddressSanitizerPass(opts));
          });
    }
    if (SanitizerOptions->SanitizeHWAddress) {
      OptimizerLastEPCallbacks.push_back(
          [SanitizerOptions](ModulePassManager &MPM, OptimizationLevel Level) {
            HWAddressSanitizerOptions opts(
                /*CompileKernel=*/false,
                SanitizerOptions->SanitizeHWAddressRecover,
                /*DisableOptimization=*/false);
            MPM.addPass(HWAddressSanitizerPass(opts));
          });
    }
  }

  ModulePassManager MPM;
  bool NeedThinLTOBufferPasses = UseThinLTOBuffers;
  if (!NoPrepopulatePasses) {
    // The pre-link pipelines don't support O0 and require using
    // buildO0DefaultPipeline() instead. At the same time, the LTO pipelines do
    // support O0 and using them is required.
    bool IsLTO = OptStage == LLVMRustOptStage::ThinLTO ||
                 OptStage == LLVMRustOptStage::FatLTO;
    if (OptLevel == OptimizationLevel::O0 && !IsLTO) {
      for (const auto &C : PipelineStartEPCallbacks)
        PB.registerPipelineStartEPCallback(C);
      for (const auto &C : OptimizerLastEPCallbacks)
        PB.registerOptimizerLastEPCallback(C);

      // We manually schedule ThinLTOBufferPasses below, so don't pass the value
      // to enable it here.
      MPM = PB.buildO0DefaultPipeline(OptLevel);
    } else {
      for (const auto &C : PipelineStartEPCallbacks)
        PB.registerPipelineStartEPCallback(C);
      for (const auto &C : OptimizerLastEPCallbacks)
        PB.registerOptimizerLastEPCallback(C);

      switch (OptStage) {
      case LLVMRustOptStage::PreLinkNoLTO:
        MPM = PB.buildPerModuleDefaultPipeline(OptLevel);
        break;
      case LLVMRustOptStage::PreLinkThinLTO:
        MPM = PB.buildThinLTOPreLinkDefaultPipeline(OptLevel);
        NeedThinLTOBufferPasses = false;
        break;
      case LLVMRustOptStage::PreLinkFatLTO:
        MPM = PB.buildLTOPreLinkDefaultPipeline(OptLevel);
        NeedThinLTOBufferPasses = false;
        break;
      case LLVMRustOptStage::ThinLTO:
        // FIXME: Does it make sense to pass the ModuleSummaryIndex?
        // It only seems to be needed for C++ specific optimizations.
        MPM = PB.buildThinLTODefaultPipeline(OptLevel, nullptr);
        break;
      case LLVMRustOptStage::FatLTO:
        MPM = PB.buildLTODefaultPipeline(OptLevel, nullptr);
        break;
      }
    }
  } else {
    // We're not building any of the default pipelines but we still want to
    // add the verifier, instrumentation, etc passes if they were requested
    for (const auto &C : PipelineStartEPCallbacks)
      C(MPM, OptLevel);
    for (const auto &C : OptimizerLastEPCallbacks)
      C(MPM, OptLevel);
  }

  if (ExtraPassesLen) {
    if (auto Err =
            PB.parsePassPipeline(MPM, StringRef(ExtraPasses, ExtraPassesLen))) {
      std::string ErrMsg = toString(std::move(Err));
      LLVMRustSetLastError(ErrMsg.c_str());
      return LLVMRustResult::Failure;
    }
  }

  if (NeedThinLTOBufferPasses) {
    MPM.addPass(CanonicalizeAliasesPass());
    MPM.addPass(NameAnonGlobalPass());
  }

  // Upgrade all calls to old intrinsics first.
  for (Module::iterator I = TheModule->begin(), E = TheModule->end(); I != E;)
    UpgradeCallsToIntrinsic(&*I++); // must be post-increment, as we remove

  MPM.run(*TheModule, MAM);
  return LLVMRustResult::Success;
}

// Callback to demangle function name
// Parameters:
// * name to be demangled
// * name len
// * output buffer
// * output buffer len
// Returns len of demangled string, or 0 if demangle failed.
typedef size_t (*DemangleFn)(const char *, size_t, char *, size_t);

namespace {

class RustAssemblyAnnotationWriter : public AssemblyAnnotationWriter {
  DemangleFn Demangle;
  std::vector<char> Buf;

public:
  RustAssemblyAnnotationWriter(DemangleFn Demangle) : Demangle(Demangle) {}

  // Return empty string if demangle failed
  // or if name does not need to be demangled
  StringRef CallDemangle(StringRef name) {
    if (!Demangle) {
      return StringRef();
    }

    if (Buf.size() < name.size() * 2) {
      // Semangled name usually shorter than mangled,
      // but allocate twice as much memory just in case
      Buf.resize(name.size() * 2);
    }

    auto R = Demangle(name.data(), name.size(), Buf.data(), Buf.size());
    if (!R) {
      // Demangle failed.
      return StringRef();
    }

    auto Demangled = StringRef(Buf.data(), R);
    if (Demangled == name) {
      // Do not print anything if demangled name is equal to mangled.
      return StringRef();
    }

    return Demangled;
  }

  void emitFunctionAnnot(const Function *F,
                         formatted_raw_ostream &OS) override {
    StringRef Demangled = CallDemangle(F->getName());
    if (Demangled.empty()) {
      return;
    }

    OS << "; " << Demangled << "\n";
  }

  void emitInstructionAnnot(const Instruction *I,
                            formatted_raw_ostream &OS) override {
    const char *Name;
    const Value *Value;
    if (const CallInst *CI = dyn_cast<CallInst>(I)) {
      Name = "call";
      Value = CI->getCalledOperand();
    } else if (const InvokeInst *II = dyn_cast<InvokeInst>(I)) {
      Name = "invoke";
      Value = II->getCalledOperand();
    } else {
      // Could demangle more operations, e. g.
      // `store %place, @function`.
      return;
    }

    if (!Value->hasName()) {
      return;
    }

    StringRef Demangled = CallDemangle(Value->getName());
    if (Demangled.empty()) {
      return;
    }

    OS << "; " << Name << " " << Demangled << "\n";
  }
};

} // namespace

extern "C" LLVMRustResult LLVMRustPrintModule(LLVMModuleRef M, const char *Path,
                                              DemangleFn Demangle) {
  std::string ErrorInfo;
  std::error_code EC;
  auto OS = raw_fd_ostream(Path, EC, sys::fs::OF_None);
  if (EC)
    ErrorInfo = EC.message();
  if (ErrorInfo != "") {
    LLVMRustSetLastError(ErrorInfo.c_str());
    return LLVMRustResult::Failure;
  }

  auto AAW = RustAssemblyAnnotationWriter(Demangle);
  auto FOS = formatted_raw_ostream(OS);
  unwrap(M)->print(FOS, &AAW);

  return LLVMRustResult::Success;
}

extern "C" void LLVMRustPrintPasses() {
  PassBuilder PB;
  PB.printPassNames(outs());
}

extern "C" void LLVMRustRunRestrictionPass(LLVMModuleRef M, char **Symbols,
                                           size_t Len) {
  auto PreserveFunctions = [=](const GlobalValue &GV) {
    // Preserve LLVM-injected, ASAN-related symbols.
    // See also https://github.com/rust-lang/rust/issues/113404.
    if (GV.getName() == "___asan_globals_registered") {
      return true;
    }

    // Preserve symbols exported from Rust modules.
    for (size_t I = 0; I < Len; I++) {
      if (GV.getName() == Symbols[I]) {
        return true;
      }
    }
    return false;
  };

  internalizeModule(*unwrap(M), PreserveFunctions);
}

extern "C" void
LLVMRustSetDataLayoutFromTargetMachine(LLVMModuleRef Module,
                                       LLVMTargetMachineRef TMR) {
  TargetMachine *Target = unwrap(TMR);
  unwrap(Module)->setDataLayout(Target->createDataLayout());
}

extern "C" void LLVMRustSetModulePICLevel(LLVMModuleRef M) {
  unwrap(M)->setPICLevel(PICLevel::Level::BigPIC);
}

extern "C" void LLVMRustSetModulePIELevel(LLVMModuleRef M) {
  unwrap(M)->setPIELevel(PIELevel::Level::Large);
}

extern "C" void LLVMRustSetModuleCodeModel(LLVMModuleRef M,
                                           LLVMRustCodeModel Model) {
  auto CM = fromRust(Model);
  if (!CM)
    return;
  unwrap(M)->setCodeModel(*CM);
}

// Here you'll find an implementation of ThinLTO as used by the Rust compiler
// right now. This ThinLTO support is only enabled on "recent ish" versions of
// LLVM, and otherwise it's just blanket rejected from other compilers.
//
// Most of this implementation is straight copied from LLVM. At the time of
// this writing it wasn't *quite* suitable to reuse more code from upstream
// for our purposes, but we should strive to upstream this support once it's
// ready to go! I figure we may want a bit of testing locally first before
// sending this upstream to LLVM. I hear though they're quite eager to receive
// feedback like this!
//
// If you're reading this code and wondering "what in the world" or you're
// working "good lord by LLVM upgrade is *still* failing due to these bindings"
// then fear not! (ok maybe fear a little). All code here is mostly based
// on `lib/LTO/ThinLTOCodeGenerator.cpp` in LLVM.
//
// You'll find that the general layout here roughly corresponds to the `run`
// method in that file as well as `ProcessThinLTOModule`. Functions are
// specifically commented below as well, but if you're updating this code
// or otherwise trying to understand it, the LLVM source will be useful in
// interpreting the mysteries within.
//
// Otherwise I'll apologize in advance, it probably requires a relatively
// significant investment on your part to "truly understand" what's going on
// here. Not saying I do myself, but it took me awhile staring at LLVM's source
// and various online resources about ThinLTO to make heads or tails of all
// this.

// This is a shared data structure which *must* be threadsafe to share
// read-only amongst threads. This also corresponds basically to the arguments
// of the `ProcessThinLTOModule` function in the LLVM source.
struct LLVMRustThinLTOData {
  // The combined index that is the global analysis over all modules we're
  // performing ThinLTO for. This is mostly managed by LLVM.
  ModuleSummaryIndex Index;

  // All modules we may look at, stored as in-memory serialized versions. This
  // is later used when inlining to ensure we can extract any module to inline
  // from.
  StringMap<MemoryBufferRef> ModuleMap;

  // A set that we manage of everything we *don't* want internalized. Note that
  // this includes all transitive references right now as well, but it may not
  // always!
  DenseSet<GlobalValue::GUID> GUIDPreservedSymbols;

  // Not 100% sure what these are, but they impact what's internalized and
  // what's inlined across modules, I believe.
#if LLVM_VERSION_GE(20, 0)
  FunctionImporter::ImportListsTy ImportLists;
#else
  DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists;
#endif
  DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists;
  DenseMap<StringRef, GVSummaryMapTy> ModuleToDefinedGVSummaries;
  StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>> ResolvedODR;

  LLVMRustThinLTOData() : Index(/* HaveGVs = */ false) {}
};

// Just an argument to the `LLVMRustCreateThinLTOData` function below.
struct LLVMRustThinLTOModule {
  const char *identifier;
  const char *data;
  size_t len;
};

// This is copied from `lib/LTO/ThinLTOCodeGenerator.cpp`, not sure what it
// does.
static const GlobalValueSummary *
getFirstDefinitionForLinker(const GlobalValueSummaryList &GVSummaryList) {
  auto StrongDefForLinker = llvm::find_if(
      GVSummaryList, [](const std::unique_ptr<GlobalValueSummary> &Summary) {
        auto Linkage = Summary->linkage();
        return !GlobalValue::isAvailableExternallyLinkage(Linkage) &&
               !GlobalValue::isWeakForLinker(Linkage);
      });
  if (StrongDefForLinker != GVSummaryList.end())
    return StrongDefForLinker->get();

  auto FirstDefForLinker = llvm::find_if(
      GVSummaryList, [](const std::unique_ptr<GlobalValueSummary> &Summary) {
        auto Linkage = Summary->linkage();
        return !GlobalValue::isAvailableExternallyLinkage(Linkage);
      });
  if (FirstDefForLinker == GVSummaryList.end())
    return nullptr;
  return FirstDefForLinker->get();
}

// The main entry point for creating the global ThinLTO analysis. The structure
// here is basically the same as before threads are spawned in the `run`
// function of `lib/LTO/ThinLTOCodeGenerator.cpp`.
extern "C" LLVMRustThinLTOData *
LLVMRustCreateThinLTOData(LLVMRustThinLTOModule *modules, size_t num_modules,
                          const char **preserved_symbols, size_t num_symbols) {
  auto Ret = std::make_unique<LLVMRustThinLTOData>();

  // Load each module's summary and merge it into one combined index
  for (size_t i = 0; i < num_modules; i++) {
    auto module = &modules[i];
    auto buffer = StringRef(module->data, module->len);
    auto mem_buffer = MemoryBufferRef(buffer, module->identifier);

    Ret->ModuleMap[module->identifier] = mem_buffer;

    if (Error Err = readModuleSummaryIndex(mem_buffer, Ret->Index)) {
      LLVMRustSetLastError(toString(std::move(Err)).c_str());
      return nullptr;
    }
  }

  // Collect for each module the list of function it defines (GUID -> Summary)
  Ret->Index.collectDefinedGVSummariesPerModule(
      Ret->ModuleToDefinedGVSummaries);

  // Convert the preserved symbols set from string to GUID, this is then needed
  // for internalization.
  for (size_t i = 0; i < num_symbols; i++) {
    auto GUID = GlobalValue::getGUID(preserved_symbols[i]);
    Ret->GUIDPreservedSymbols.insert(GUID);
  }

  // Collect the import/export lists for all modules from the call-graph in the
  // combined index
  //
  // This is copied from `lib/LTO/ThinLTOCodeGenerator.cpp`
  auto deadIsPrevailing = [&](GlobalValue::GUID G) {
    return PrevailingType::Unknown;
  };
  // We don't have a complete picture in our use of ThinLTO, just our immediate
  // crate, so we need `ImportEnabled = false` to limit internalization.
  // Otherwise, we sometimes lose `static` values -- see #60184.
  computeDeadSymbolsWithConstProp(Ret->Index, Ret->GUIDPreservedSymbols,
                                  deadIsPrevailing,
                                  /* ImportEnabled = */ false);
  // Resolve LinkOnce/Weak symbols, this has to be computed early be cause it
  // impacts the caching.
  //
  // This is copied from `lib/LTO/ThinLTOCodeGenerator.cpp` with some of this
  // being lifted from `lib/LTO/LTO.cpp` as well
  DenseMap<GlobalValue::GUID, const GlobalValueSummary *> PrevailingCopy;
  for (auto &I : Ret->Index) {
    if (I.second.SummaryList.size() > 1)
      PrevailingCopy[I.first] =
          getFirstDefinitionForLinker(I.second.SummaryList);
  }
  auto isPrevailing = [&](GlobalValue::GUID GUID, const GlobalValueSummary *S) {
    const auto &Prevailing = PrevailingCopy.find(GUID);
    if (Prevailing == PrevailingCopy.end())
      return true;
    return Prevailing->second == S;
  };
  ComputeCrossModuleImport(Ret->Index, Ret->ModuleToDefinedGVSummaries,
                           isPrevailing, Ret->ImportLists, Ret->ExportLists);

  auto recordNewLinkage = [&](StringRef ModuleIdentifier,
                              GlobalValue::GUID GUID,
                              GlobalValue::LinkageTypes NewLinkage) {
    Ret->ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
  };

  // Uses FromPrevailing visibility scheme which works for many binary
  // formats. We probably could and should use ELF visibility scheme for many of
  // our targets, however.
  lto::Config conf;
  thinLTOResolvePrevailingInIndex(conf, Ret->Index, isPrevailing,
                                  recordNewLinkage, Ret->GUIDPreservedSymbols);

  // Here we calculate an `ExportedGUIDs` set for use in the `isExported`
  // callback below. This callback below will dictate the linkage for all
  // summaries in the index, and we basically just only want to ensure that dead
  // symbols are internalized. Otherwise everything that's already external
  // linkage will stay as external, and internal will stay as internal.
  std::set<GlobalValue::GUID> ExportedGUIDs;
  for (auto &List : Ret->Index) {
    for (auto &GVS : List.second.SummaryList) {
      if (GlobalValue::isLocalLinkage(GVS->linkage()))
        continue;
      auto GUID = GVS->getOriginalName();
      if (GVS->flags().Live)
        ExportedGUIDs.insert(GUID);
    }
  }
  auto isExported = [&](StringRef ModuleIdentifier, ValueInfo VI) {
    const auto &ExportList = Ret->ExportLists.find(ModuleIdentifier);
    return (ExportList != Ret->ExportLists.end() &&
            ExportList->second.count(VI)) ||
           ExportedGUIDs.count(VI.getGUID());
  };
  thinLTOInternalizeAndPromoteInIndex(Ret->Index, isExported, isPrevailing);

  return Ret.release();
}

extern "C" void LLVMRustFreeThinLTOData(LLVMRustThinLTOData *Data) {
  delete Data;
}

// Below are the various passes that happen *per module* when doing ThinLTO.
//
// In other words, these are the functions that are all run concurrently
// with one another, one per module. The passes here correspond to the analysis
// passes in `lib/LTO/ThinLTOCodeGenerator.cpp`, currently found in the
// `ProcessThinLTOModule` function. Here they're split up into separate steps
// so rustc can save off the intermediate bytecode between each step.

static bool clearDSOLocalOnDeclarations(Module &Mod, TargetMachine &TM) {
  // When linking an ELF shared object, dso_local should be dropped. We
  // conservatively do this for -fpic.
  bool ClearDSOLocalOnDeclarations = TM.getTargetTriple().isOSBinFormatELF() &&
                                     TM.getRelocationModel() != Reloc::Static &&
                                     Mod.getPIELevel() == PIELevel::Default;
  return ClearDSOLocalOnDeclarations;
}

extern "C" bool LLVMRustPrepareThinLTORename(const LLVMRustThinLTOData *Data,
                                             LLVMModuleRef M,
                                             LLVMTargetMachineRef TM) {
  Module &Mod = *unwrap(M);
  TargetMachine &Target = *unwrap(TM);

  bool ClearDSOLocal = clearDSOLocalOnDeclarations(Mod, Target);
  bool error = renameModuleForThinLTO(Mod, Data->Index, ClearDSOLocal);

  if (error) {
    LLVMRustSetLastError("renameModuleForThinLTO failed");
    return false;
  }
  return true;
}

extern "C" bool
LLVMRustPrepareThinLTOResolveWeak(const LLVMRustThinLTOData *Data,
                                  LLVMModuleRef M) {
  Module &Mod = *unwrap(M);
  const auto &DefinedGlobals =
      Data->ModuleToDefinedGVSummaries.lookup(Mod.getModuleIdentifier());
  thinLTOFinalizeInModule(Mod, DefinedGlobals, /*PropagateAttrs=*/true);
  return true;
}

extern "C" bool
LLVMRustPrepareThinLTOInternalize(const LLVMRustThinLTOData *Data,
                                  LLVMModuleRef M) {
  Module &Mod = *unwrap(M);
  const auto &DefinedGlobals =
      Data->ModuleToDefinedGVSummaries.lookup(Mod.getModuleIdentifier());
  thinLTOInternalizeModule(Mod, DefinedGlobals);
  return true;
}

extern "C" bool LLVMRustPrepareThinLTOImport(const LLVMRustThinLTOData *Data,
                                             LLVMModuleRef M,
                                             LLVMTargetMachineRef TM) {
  Module &Mod = *unwrap(M);
  TargetMachine &Target = *unwrap(TM);

  const auto &ImportList = Data->ImportLists.lookup(Mod.getModuleIdentifier());
  auto Loader = [&](StringRef Identifier) {
    const auto &Memory = Data->ModuleMap.lookup(Identifier);
    auto &Context = Mod.getContext();
    auto MOrErr = getLazyBitcodeModule(Memory, Context, true, true);

    if (!MOrErr)
      return MOrErr;

    // The rest of this closure is a workaround for
    // https://bugs.llvm.org/show_bug.cgi?id=38184 where during ThinLTO imports
    // we accidentally import wasm custom sections into different modules,
    // duplicating them by in the final output artifact.
    //
    // The issue is worked around here by manually removing the
    // `wasm.custom_sections` named metadata node from any imported module. This
    // we know isn't used by any optimization pass so there's no need for it to
    // be imported.
    //
    // Note that the metadata is currently lazily loaded, so we materialize it
    // here before looking up if there's metadata inside. The `FunctionImporter`
    // will immediately materialize metadata anyway after an import, so this
    // shouldn't be a perf hit.
    if (Error Err = (*MOrErr)->materializeMetadata()) {
      Expected<std::unique_ptr<Module>> Ret(std::move(Err));
      return Ret;
    }

    auto *WasmCustomSections =
        (*MOrErr)->getNamedMetadata("wasm.custom_sections");
    if (WasmCustomSections)
      WasmCustomSections->eraseFromParent();

    // `llvm.ident` named metadata also gets duplicated.
    auto *llvmIdent = (*MOrErr)->getNamedMetadata("llvm.ident");
    if (llvmIdent)
      llvmIdent->eraseFromParent();

    return MOrErr;
  };
  bool ClearDSOLocal = clearDSOLocalOnDeclarations(Mod, Target);
  auto Importer = FunctionImporter(Data->Index, Loader, ClearDSOLocal);
  Expected<bool> Result = Importer.importFunctions(Mod, ImportList);
  if (!Result) {
    LLVMRustSetLastError(toString(Result.takeError()).c_str());
    return false;
  }
  return true;
}

// This struct and various functions are sort of a hack right now, but the
// problem is that we've got in-memory LLVM modules after we generate and
// optimize all codegen-units for one compilation in rustc. To be compatible
// with the LTO support above we need to serialize the modules plus their
// ThinLTO summary into memory.
//
// This structure is basically an owned version of a serialize module, with
// a ThinLTO summary attached.
struct LLVMRustThinLTOBuffer {
  std::string data;
  std::string thin_link_data;
};

extern "C" LLVMRustThinLTOBuffer *
LLVMRustThinLTOBufferCreate(LLVMModuleRef M, bool is_thin, bool emit_summary) {
  auto Ret = std::make_unique<LLVMRustThinLTOBuffer>();
  {
    auto OS = raw_string_ostream(Ret->data);
    auto ThinLinkOS = raw_string_ostream(Ret->thin_link_data);
    {
      if (is_thin) {
        PassBuilder PB;
        LoopAnalysisManager LAM;
        FunctionAnalysisManager FAM;
        CGSCCAnalysisManager CGAM;
        ModuleAnalysisManager MAM;
        PB.registerModuleAnalyses(MAM);
        PB.registerCGSCCAnalyses(CGAM);
        PB.registerFunctionAnalyses(FAM);
        PB.registerLoopAnalyses(LAM);
        PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
        ModulePassManager MPM;
        // We only pass ThinLinkOS to be filled in if we want the summary,
        // because otherwise LLVM does extra work and may double-emit some
        // errors or warnings.
        MPM.addPass(
            ThinLTOBitcodeWriterPass(OS, emit_summary ? &ThinLinkOS : nullptr));
        MPM.run(*unwrap(M), MAM);
      } else {
        WriteBitcodeToFile(*unwrap(M), OS);
      }
    }
  }
  return Ret.release();
}

extern "C" void LLVMRustThinLTOBufferFree(LLVMRustThinLTOBuffer *Buffer) {
  delete Buffer;
}

extern "C" const void *
LLVMRustThinLTOBufferPtr(const LLVMRustThinLTOBuffer *Buffer) {
  return Buffer->data.data();
}

extern "C" size_t
LLVMRustThinLTOBufferLen(const LLVMRustThinLTOBuffer *Buffer) {
  return Buffer->data.length();
}

extern "C" const void *
LLVMRustThinLTOBufferThinLinkDataPtr(const LLVMRustThinLTOBuffer *Buffer) {
  return Buffer->thin_link_data.data();
}

extern "C" size_t
LLVMRustThinLTOBufferThinLinkDataLen(const LLVMRustThinLTOBuffer *Buffer) {
  return Buffer->thin_link_data.length();
}

// This is what we used to parse upstream bitcode for actual ThinLTO
// processing. We'll call this once per module optimized through ThinLTO, and
// it'll be called concurrently on many threads.
extern "C" LLVMModuleRef LLVMRustParseBitcodeForLTO(LLVMContextRef Context,
                                                    const char *data,
                                                    size_t len,
                                                    const char *identifier) {
  auto Data = StringRef(data, len);
  auto Buffer = MemoryBufferRef(Data, identifier);
  unwrap(Context)->enableDebugTypeODRUniquing();
  Expected<std::unique_ptr<Module>> SrcOrError =
      parseBitcodeFile(Buffer, *unwrap(Context));
  if (!SrcOrError) {
    LLVMRustSetLastError(toString(SrcOrError.takeError()).c_str());
    return nullptr;
  }
  return wrap(std::move(*SrcOrError).release());
}

// Find a section of an object file by name. Fail if the section is missing or
// empty.
extern "C" const char *LLVMRustGetSliceFromObjectDataByName(const char *data,
                                                            size_t len,
                                                            const char *name,
                                                            size_t name_len,
                                                            size_t *out_len) {
  *out_len = 0;
  auto Name = StringRef(name, name_len);
  auto Data = StringRef(data, len);
  auto Buffer = MemoryBufferRef(Data, ""); // The id is unused.
  file_magic Type = identify_magic(Buffer.getBuffer());
  Expected<std::unique_ptr<object::ObjectFile>> ObjFileOrError =
      object::ObjectFile::createObjectFile(Buffer, Type);
  if (!ObjFileOrError) {
    LLVMRustSetLastError(toString(ObjFileOrError.takeError()).c_str());
    return nullptr;
  }
  for (const object::SectionRef &Sec : (*ObjFileOrError)->sections()) {
    Expected<StringRef> SecName = Sec.getName();
    if (SecName && *SecName == Name) {
      Expected<StringRef> SectionOrError = Sec.getContents();
      if (!SectionOrError) {
        LLVMRustSetLastError(toString(SectionOrError.takeError()).c_str());
        return nullptr;
      }
      *out_len = SectionOrError->size();
      return SectionOrError->data();
    }
  }
  LLVMRustSetLastError("could not find requested section");
  return nullptr;
}

// Computes the LTO cache key for the provided 'ModId' in the given 'Data',
// storing the result in 'KeyOut'.
// Currently, this cache key is a SHA-1 hash of anything that could affect
// the result of optimizing this module (e.g. module imports, exports, liveness
// of access globals, etc).
// The precise details are determined by LLVM in `computeLTOCacheKey`, which is
// used during the normal linker-plugin incremental thin-LTO process.
extern "C" void LLVMRustComputeLTOCacheKey(RustStringRef KeyOut,
                                           const char *ModId,
                                           LLVMRustThinLTOData *Data) {
  SmallString<40> Key;
  llvm::lto::Config conf;
  const auto &ImportList = Data->ImportLists.lookup(ModId);
  const auto &ExportList = Data->ExportLists.lookup(ModId);
  const auto &ResolvedODR = Data->ResolvedODR.lookup(ModId);
  const auto &DefinedGlobals = Data->ModuleToDefinedGVSummaries.lookup(ModId);
#if LLVM_VERSION_GE(20, 0)
  DenseSet<GlobalValue::GUID> CfiFunctionDefs;
  DenseSet<GlobalValue::GUID> CfiFunctionDecls;
#else
  std::set<GlobalValue::GUID> CfiFunctionDefs;
  std::set<GlobalValue::GUID> CfiFunctionDecls;
#endif

  // Based on the 'InProcessThinBackend' constructor in LLVM
  for (auto &Name : Data->Index.cfiFunctionDefs())
    CfiFunctionDefs.insert(
        GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(Name)));
  for (auto &Name : Data->Index.cfiFunctionDecls())
    CfiFunctionDecls.insert(
        GlobalValue::getGUID(GlobalValue::dropLLVMManglingEscape(Name)));

#if LLVM_VERSION_GE(20, 0)
  Key = llvm::computeLTOCacheKey(conf, Data->Index, ModId, ImportList,
                                 ExportList, ResolvedODR, DefinedGlobals,
                                 CfiFunctionDefs, CfiFunctionDecls);
#else
  llvm::computeLTOCacheKey(Key, conf, Data->Index, ModId, ImportList,
                           ExportList, ResolvedODR, DefinedGlobals,
                           CfiFunctionDefs, CfiFunctionDecls);
#endif

  LLVMRustStringWriteImpl(KeyOut, Key.c_str(), Key.size());
}