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-rw-r--r--compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp1592
1 files changed, 1592 insertions, 0 deletions
diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
new file mode 100644
index 00000000000..55e1c84c8a2
--- /dev/null
+++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
@@ -0,0 +1,1592 @@
+#include <stdio.h>
+
+#include <cstddef>
+#include <iomanip>
+#include <vector>
+#include <set>
+
+#include "LLVMWrapper.h"
+
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/CodeGen/CommandFlags.h"
+#include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/IR/AutoUpgrade.h"
+#include "llvm/IR/AssemblyAnnotationWriter.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Verifier.h"
+#include "llvm/MC/TargetRegistry.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Object/IRObjectFile.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"
+#if LLVM_VERSION_GE(17, 0)
+#include "llvm/Support/VirtualFileSystem.h"
+#endif
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Transforms/IPO/AlwaysInliner.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/Utils/AddDiscriminators.h"
+#include "llvm/Transforms/Utils/FunctionImportUtils.h"
+#include "llvm/LTO/LTO.h"
+#include "llvm/Bitcode/BitcodeWriter.h"
+
+#include "llvm/Transforms/Instrumentation.h"
+#include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
+#include "llvm/Support/TimeProfiler.h"
+#include "llvm/Transforms/Instrumentation/GCOVProfiler.h"
+#include "llvm/Transforms/Instrumentation/InstrProfiling.h"
+#include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
+#include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
+#include "llvm/Transforms/Instrumentation/HWAddressSanitizer.h"
+#include "llvm/Transforms/Utils/CanonicalizeAliases.h"
+#include "llvm/Transforms/Utils/NameAnonGlobals.h"
+#include "llvm/Transforms/Utils.h"
+
+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) {
+  StringRef FN(FileName);
+  std::error_code EC;
+  raw_fd_ostream OS(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_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_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,
+};
+
+#if LLVM_VERSION_GE(18, 0)
+  using CodeGenOptLevelEnum = llvm::CodeGenOptLevel;
+#else
+  using CodeGenOptLevelEnum = llvm::CodeGenOpt::Level;
+#endif
+
+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;
+}
+
+using PrintBackendInfo = void(void*, const char* Data, size_t Len);
+
+extern "C" void LLVMRustPrintTargetCPUs(LLVMTargetMachineRef TM,
+                                        const char* TargetCPU,
+                                        PrintBackendInfo Print,
+                                        void* Out) {
+  const TargetMachine *Target = unwrap(TM);
+  const Triple::ArchType HostArch = Triple(sys::getDefaultTargetTriple()).getArch();
+  const Triple::ArchType TargetArch = Target->getTargetTriple().getArch();
+
+  std::ostringstream Buf;
+
+#if LLVM_VERSION_GE(17, 0)
+  const MCSubtargetInfo *MCInfo = Target->getMCSubtargetInfo();
+  const ArrayRef<SubtargetSubTypeKV> CPUTable = MCInfo->getAllProcessorDescriptions();
+#else
+  Buf << "Full target CPU help is not supported by this LLVM version.\n\n";
+  SubtargetSubTypeKV TargetCPUKV = { TargetCPU, {{}}, {{}} };
+  const ArrayRef<SubtargetSubTypeKV> CPUTable = TargetCPUKV;
+#endif
+  unsigned MaxCPULen = getLongestEntryLength(CPUTable);
+
+  Buf << "Available CPUs for this target:\n";
+  // Don't print the "native" entry when the user specifies --target with a
+  // different arch since that could be wrong or misleading.
+  if (HostArch == TargetArch) {
+    MaxCPULen = std::max(MaxCPULen, (unsigned) std::strlen("native"));
+    const StringRef HostCPU = sys::getHostCPUName();
+    Buf << "    " << std::left << std::setw(MaxCPULen) << "native"
+        << " - Select the CPU of the current host "
+           "(currently " << HostCPU.str() << ").\n";
+  }
+  for (auto &CPU : CPUTable) {
+    // Compare cpu against current target to label the default
+    if (strcmp(CPU.Key, TargetCPU) == 0) {
+      Buf << "    " << std::left << std::setw(MaxCPULen) << CPU.Key
+          << " - This is the default target CPU for the current build target "
+             "(currently " << Target->getTargetTriple().str() << ").";
+    }
+    else {
+      Buf << "    " << CPU.Key;
+    }
+    Buf << "\n";
+  }
+
+  const auto &BufString = Buf.str();
+  Print(Out, BufString.data(), BufString.size());
+}
+
+extern "C" size_t LLVMRustGetTargetFeaturesCount(LLVMTargetMachineRef TM) {
+#ifdef LLVM_RUSTLLVM
+  const TargetMachine *Target = unwrap(TM);
+  const MCSubtargetInfo *MCInfo = Target->getMCSubtargetInfo();
+  const ArrayRef<SubtargetFeatureKV> FeatTable = MCInfo->getFeatureTable();
+  return FeatTable.size();
+#else
+  return 0;
+#endif
+}
+
+extern "C" void LLVMRustGetTargetFeature(LLVMTargetMachineRef TM, size_t Index,
+                                         const char** Feature, const char** Desc) {
+#ifdef LLVM_RUSTLLVM
+  const TargetMachine *Target = unwrap(TM);
+  const MCSubtargetInfo *MCInfo = Target->getMCSubtargetInfo();
+  const ArrayRef<SubtargetFeatureKV> FeatTable = MCInfo->getFeatureTable();
+  const SubtargetFeatureKV Feat = FeatTable[Index];
+  *Feature = Feat.Key;
+  *Desc = Feat.Desc;
+#endif
+}
+
+extern "C" const char* LLVMRustGetHostCPUName(size_t *len) {
+  StringRef Name = sys::getHostCPUName();
+  *len = 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 AsmComments,
+    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;
+  Triple Trip(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 = AsmComments;
+  Options.MCOptions.PreserveAsmComments = AsmComments;
+  Options.MCOptions.ABIName = ABIStr;
+  if (SplitDwarfFile) {
+      Options.MCOptions.SplitDwarfFile = SplitDwarfFile;
+  }
+  if (OutputObjFile) {
+      Options.ObjectFilenameForDebug = OutputObjFile;
+  }
+  if (!strcmp("zlib", DebugInfoCompression) && llvm::compression::zlib::isAvailable()) {
+    Options.CompressDebugSections = DebugCompressionType::Zlib;
+  } else if (!strcmp("zstd", DebugInfoCompression) && llvm::compression::zstd::isAvailable()) {
+    Options.CompressDebugSections = DebugCompressionType::Zstd;
+  } else if (!strcmp("none", DebugInfoCompression)) {
+    Options.CompressDebugSections = DebugCompressionType::None;
+  }
+
+  Options.RelaxELFRelocations = RelaxELFRelocations;
+  Options.UseInitArray = UseInitArray;
+
+#if LLVM_VERSION_LT(17, 0)
+  Options.ExplicitEmulatedTLS = true;
+#endif
+  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;
+  }
+
+  if (Singlethread) {
+    Options.ThreadModel = ThreadModel::Single;
+  }
+
+  Options.EmitStackSizeSection = EmitStackSizeSection;
+
+
+  if (ArgsCstrBuff != nullptr)
+  {
+    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);
+  }
+
+  TargetMachine *TM = TheTarget->createTargetMachine(
+      Trip.getTriple(), CPU, Feature, Options, RM, CM, OptLevel);
+  return wrap(TM);
+}
+
+extern "C" void LLVMRustDisposeTargetMachine(LLVMTargetMachineRef TM) {
+
+  MCTargetOptions& MCOptions = unwrap(TM)->Options.MCOptions;
+  delete[] MCOptions.Argv0;
+  delete[] MCOptions.CommandLineArgs.data();
+
+  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) {
+  Triple TargetTriple(unwrap(M)->getTargetTriple());
+  TargetLibraryInfoImpl TLII(TargetTriple);
+  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:
+#if LLVM_VERSION_GE(18, 0)
+    return CodeGenFileType::AssemblyFile;
+#else
+    return CGFT_AssemblyFile;
+#endif
+  case LLVMRustFileType::ObjectFile:
+#if LLVM_VERSION_GE(18, 0)
+    return CodeGenFileType::ObjectFile;
+#else
+    return CGFT_ObjectFile;
+#endif
+  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;
+  raw_fd_ostream OS(Path, EC, sys::fs::OF_None);
+  if (EC)
+    ErrorInfo = EC.message();
+  if (ErrorInfo != "") {
+    LLVMRustSetLastError(ErrorInfo.c_str());
+    return LLVMRustResult::Failure;
+  }
+
+  buffer_ostream BOS(OS);
+  if (DwoPath) {
+    raw_fd_ostream DOS(DwoPath, EC, sys::fs::OF_None);
+    EC.clear();
+    if (EC)
+        ErrorInfo = EC.message();
+    if (ErrorInfo != "") {
+      LLVMRustSetLastError(ErrorInfo.c_str());
+      return LLVMRustResult::Failure;
+    }
+    buffer_ostream DBOS(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 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 UseThinLTOBuffers,
+    bool MergeFunctions, bool UnrollLoops, bool SLPVectorize, bool LoopVectorize,
+    bool EmitLifetimeMarkers,
+    LLVMRustSanitizerOptions *SanitizerOptions,
+    const char *PGOGenPath, const char *PGOUsePath,
+    bool InstrumentCoverage, const char *InstrProfileOutput,
+    bool InstrumentGCOV,
+    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;
+
+  // FIXME: We may want to expose this as an option.
+  bool DebugPassManager = false;
+
+  PassInstrumentationCallbacks PIC;
+  StandardInstrumentations SI(TheModule->getContext(), DebugPassManager);
+  SI.registerCallbacks(PIC);
+
+  if (LlvmSelfProfiler){
+    LLVMSelfProfileInitializeCallbacks(PIC,LlvmSelfProfiler,BeforePassCallback,AfterPassCallback);
+  }
+
+  std::optional<PGOOptions> PGOOpt;
+#if LLVM_VERSION_GE(17, 0)
+  auto FS = vfs::getRealFileSystem();
+#endif
+  if (PGOGenPath) {
+    assert(!PGOUsePath && !PGOSampleUsePath);
+    PGOOpt = PGOOptions(PGOGenPath, "", "",
+#if LLVM_VERSION_GE(17, 0)
+                        "",
+                        FS,
+#endif
+                        PGOOptions::IRInstr, PGOOptions::NoCSAction,
+                        DebugInfoForProfiling);
+  } else if (PGOUsePath) {
+    assert(!PGOSampleUsePath);
+    PGOOpt = PGOOptions(PGOUsePath, "", "",
+#if LLVM_VERSION_GE(17, 0)
+                        "",
+                        FS,
+#endif
+                        PGOOptions::IRUse, PGOOptions::NoCSAction,
+                        DebugInfoForProfiling);
+  } else if (PGOSampleUsePath) {
+    PGOOpt = PGOOptions(PGOSampleUsePath, "", "",
+#if LLVM_VERSION_GE(17, 0)
+                        "",
+                        FS,
+#endif
+                        PGOOptions::SampleUse, PGOOptions::NoCSAction,
+                        DebugInfoForProfiling);
+  } else if (DebugInfoForProfiling) {
+    PGOOpt = PGOOptions("", "", "",
+#if LLVM_VERSION_GE(17, 0)
+                        "",
+                        FS,
+#endif
+                        PGOOptions::NoAction, PGOOptions::NoCSAction,
+                        DebugInfoForProfiling);
+  }
+
+  PassBuilder PB(TM, PTO, PGOOpt, &PIC);
+  LoopAnalysisManager LAM;
+  FunctionAnalysisManager FAM;
+  CGSCCAnalysisManager CGAM;
+  ModuleAnalysisManager 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) {
+        LLVMRustSetLastError(("Failed to load pass plugin" + PluginPath.str()).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));
+  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,
+                                       /*DropTypeTests=*/false));
+      }
+    );
+  }
+
+  if (VerifyIR) {
+    PipelineStartEPCallbacks.push_back(
+      [VerifyIR](ModulePassManager &MPM, OptimizationLevel Level) {
+        MPM.addPass(VerifierPass());
+      }
+    );
+  }
+
+  if (InstrumentGCOV) {
+    PipelineStartEPCallbacks.push_back(
+      [](ModulePassManager &MPM, OptimizationLevel Level) {
+        MPM.addPass(GCOVProfilerPass(GCOVOptions::getDefault()));
+      }
+    );
+  }
+
+  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(InstrProfiling(Options, false));
+      }
+    );
+  }
+
+  if (SanitizerOptions) {
+    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);
+
+      // Pass false as we manually schedule ThinLTOBufferPasses below.
+      MPM = PB.buildO0DefaultPipeline(OptLevel, /* PreLinkLTO */ false);
+    } else {
+      for (const auto &C : PipelineStartEPCallbacks)
+        PB.registerPipelineStartEPCallback(C);
+      if (OptStage != LLVMRustOptStage::PreLinkThinLTO) {
+        for (const auto &C : OptimizerLastEPCallbacks)
+          PB.registerOptimizerLastEPCallback(C);
+      }
+
+      switch (OptStage) {
+      case LLVMRustOptStage::PreLinkNoLTO:
+        MPM = PB.buildPerModuleDefaultPipeline(OptLevel, DebugPassManager);
+        break;
+      case LLVMRustOptStage::PreLinkThinLTO:
+        MPM = PB.buildThinLTOPreLinkDefaultPipeline(OptLevel);
+        // The ThinLTOPreLink pipeline already includes ThinLTOBuffer passes. However, callback
+        // passes may still run afterwards. This means we need to run the buffer passes again.
+        // FIXME: In LLVM 13, the ThinLTOPreLink pipeline also runs OptimizerLastEPCallbacks
+        // before the RequiredLTOPreLinkPasses, in which case we can remove these hacks.
+        if (OptimizerLastEPCallbacks.empty())
+          NeedThinLTOBufferPasses = false;
+        for (const auto &C : OptimizerLastEPCallbacks)
+          C(MPM, OptLevel);
+        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;
+  raw_fd_ostream OS(Path, EC, sys::fs::OF_None);
+  if (EC)
+    ErrorInfo = EC.message();
+  if (ErrorInfo != "") {
+    LLVMRustSetLastError(ErrorInfo.c_str());
+    return LLVMRustResult::Failure;
+  }
+
+  RustAssemblyAnnotationWriter AAW(Demangle);
+  formatted_raw_ostream FOS(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(18, 0)
+  DenseMap<StringRef, FunctionImporter::ImportMapTy> ImportLists;
+  DenseMap<StringRef, FunctionImporter::ExportSetTy> ExportLists;
+  DenseMap<StringRef, GVSummaryMapTy> ModuleToDefinedGVSummaries;
+#else
+  StringMap<FunctionImporter::ImportMapTy> ImportLists;
+  StringMap<FunctionImporter::ExportSetTy> ExportLists;
+  StringMap<GVSummaryMapTy> ModuleToDefinedGVSummaries;
+#endif
+  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,
+                          int num_modules,
+                          const char **preserved_symbols,
+                          int num_symbols) {
+  auto Ret = std::make_unique<LLVMRustThinLTOData>();
+
+  // Load each module's summary and merge it into one combined index
+  for (int i = 0; i < num_modules; i++) {
+    auto module = &modules[i];
+    StringRef buffer(module->data, module->len);
+    MemoryBufferRef mem_buffer(buffer, module->identifier);
+
+    Ret->ModuleMap[module->identifier] = mem_buffer;
+
+#if LLVM_VERSION_GE(18, 0)
+    if (Error Err = readModuleSummaryIndex(mem_buffer, Ret->Index)) {
+#else
+    if (Error Err = readModuleSummaryIndex(mem_buffer, Ret->Index, i)) {
+#endif
+      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 (int 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,
+#if LLVM_VERSION_GE(17, 0)
+    isPrevailing,
+#endif
+    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);
+  FunctionImporter Importer(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;
+};
+
+extern "C" LLVMRustThinLTOBuffer*
+LLVMRustThinLTOBufferCreate(LLVMModuleRef M, bool is_thin) {
+  auto Ret = std::make_unique<LLVMRustThinLTOBuffer>();
+  {
+    raw_string_ostream OS(Ret->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;
+        MPM.addPass(ThinLTOBitcodeWriterPass(OS, 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();
+}
+
+// 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) {
+  StringRef Data(data, len);
+  MemoryBufferRef Buffer(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 *out_len) {
+  *out_len = 0;
+  StringRef Data(data, len);
+  MemoryBufferRef Buffer(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> Name = Sec.getName();
+    if (Name && *Name == 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);
+  std::set<GlobalValue::GUID> CfiFunctionDefs;
+  std::set<GlobalValue::GUID> CfiFunctionDecls;
+
+  // 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)));
+
+  llvm::computeLTOCacheKey(Key, conf, Data->Index, ModId,
+      ImportList, ExportList, ResolvedODR, DefinedGlobals, CfiFunctionDefs, CfiFunctionDecls
+  );
+
+  LLVMRustStringWriteImpl(KeyOut, Key.c_str(), Key.size());
+}