text: //===-- MCJIT.cpp - MC-based Just-in-Time Compiler ------------------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  
  #include "MCJIT.h"
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ExecutionEngine/GenericValue.h"
  #include "llvm/ExecutionEngine/JITEventListener.h"
  #include "llvm/ExecutionEngine/MCJIT.h"
  #include "llvm/ExecutionEngine/SectionMemoryManager.h"
  #include "llvm/IR/DataLayout.h"
  #include "llvm/IR/DerivedTypes.h"
  #include "llvm/IR/Function.h"
  #include "llvm/IR/LegacyPassManager.h"
  #include "llvm/IR/Mangler.h"
  #include "llvm/IR/Module.h"
  #include "llvm/Object/Archive.h"
  #include "llvm/Object/ObjectFile.h"
  #include "llvm/Support/DynamicLibrary.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/MemoryBuffer.h"
  #include "llvm/Support/MutexGuard.h"
  
  using namespace llvm;
  
  namespace {
  
  static struct RegisterJIT {
    RegisterJIT() { MCJIT::Register(); }
  } JITRegistrator;
  
  }
  
  extern "C" void LLVMLinkInMCJIT() {
  }
  
  ExecutionEngine *
  MCJIT::createJIT(std::unique_ptr<Module> M, std::string *ErrorStr,
                   std::shared_ptr<MCJITMemoryManager> MemMgr,
                   std::shared_ptr<LegacyJITSymbolResolver> Resolver,
                   std::unique_ptr<TargetMachine> TM) {
    // Try to register the program as a source of symbols to resolve against.
    //
    // FIXME: Don't do this here.
    sys::DynamicLibrary::LoadLibraryPermanently(nullptr, nullptr);
  
    if (!MemMgr || !Resolver) {
      auto RTDyldMM = std::make_shared<SectionMemoryManager>();
      if (!MemMgr)
        MemMgr = RTDyldMM;
      if (!Resolver)
        Resolver = RTDyldMM;
    }
  
    return new MCJIT(std::move(M), std::move(TM), std::move(MemMgr),
                     std::move(Resolver));
  }
  
  MCJIT::MCJIT(std::unique_ptr<Module> M, std::unique_ptr<TargetMachine> TM,
               std::shared_ptr<MCJITMemoryManager> MemMgr,
               std::shared_ptr<LegacyJITSymbolResolver> Resolver)
      : ExecutionEngine(TM->createDataLayout(), std::move(M)), TM(std::move(TM)),
        Ctx(nullptr), MemMgr(std::move(MemMgr)),
        Resolver(*this, std::move(Resolver)), Dyld(*this->MemMgr, this->Resolver),
        ObjCache(nullptr) {
    // FIXME: We are managing our modules, so we do not want the base class
    // ExecutionEngine to manage them as well. To avoid double destruction
    // of the first (and only) module added in ExecutionEngine constructor
    // we remove it from EE and will destruct it ourselves.
    //
    // It may make sense to move our module manager (based on SmallStPtr) back
    // into EE if the JIT and Interpreter can live with it.
    // If so, additional functions: addModule, removeModule, FindFunctionNamed,
    // runStaticConstructorsDestructors could be moved back to EE as well.
    //
    std::unique_ptr<Module> First = std::move(Modules[0]);
    Modules.clear();
  
    if (First->getDataLayout().isDefault())
      First->setDataLayout(getDataLayout());
  
    OwnedModules.addModule(std::move(First));
    RegisterJITEventListener(JITEventListener::createGDBRegistrationListener());
  }
  
  MCJIT::~MCJIT() {
    MutexGuard locked(lock);
  
    Dyld.deregisterEHFrames();
  
    for (auto &Obj : LoadedObjects)
      if (Obj)
        notifyFreeingObject(*Obj);
  
    Archives.clear();
  }
  
  void MCJIT::addModule(std::unique_ptr<Module> M) {
    MutexGuard locked(lock);
  
    if (M->getDataLayout().isDefault())
      M->setDataLayout(getDataLayout());
  
    OwnedModules.addModule(std::move(M));
  }
  
  bool MCJIT::removeModule(Module *M) {
    MutexGuard locked(lock);
    return OwnedModules.removeModule(M);
  }
  
  void MCJIT::addObjectFile(std::unique_ptr<object::ObjectFile> Obj) {
    std::unique_ptr<RuntimeDyld::LoadedObjectInfo> L = Dyld.loadObject(*Obj);
    if (Dyld.hasError())
      report_fatal_error(Dyld.getErrorString());
  
    notifyObjectLoaded(*Obj, *L);
  
    LoadedObjects.push_back(std::move(Obj));
  }
  
  void MCJIT::addObjectFile(object::OwningBinary<object::ObjectFile> Obj) {
    std::unique_ptr<object::ObjectFile> ObjFile;
    std::unique_ptr<MemoryBuffer> MemBuf;
    std::tie(ObjFile, MemBuf) = Obj.takeBinary();
    addObjectFile(std::move(ObjFile));
    Buffers.push_back(std::move(MemBuf));
  }
  
  void MCJIT::addArchive(object::OwningBinary<object::Archive> A) {
    Archives.push_back(std::move(A));
  }
  
  void MCJIT::setObjectCache(ObjectCache* NewCache) {
    MutexGuard locked(lock);
    ObjCache = NewCache;
  }
  
  std::unique_ptr<MemoryBuffer> MCJIT::emitObject(Module *M) {
    assert(M && "Can not emit a null module");
  
    MutexGuard locked(lock);
  
    // Materialize all globals in the module if they have not been
    // materialized already.
    cantFail(M->materializeAll());
  
    // This must be a module which has already been added but not loaded to this
    // MCJIT instance, since these conditions are tested by our caller,
    // generateCodeForModule.
  
    legacy::PassManager PM;
  
    // The RuntimeDyld will take ownership of this shortly
    SmallVector<char, 4096> ObjBufferSV;
    raw_svector_ostream ObjStream(ObjBufferSV);
  
    // Turn the machine code intermediate representation into bytes in memory
    // that may be executed.
    if (TM->addPassesToEmitMC(PM, Ctx, ObjStream, !getVerifyModules()))
      report_fatal_error("Target does not support MC emission!");
  
    // Initialize passes.
    PM.run(*M);
    // Flush the output buffer to get the generated code into memory
  
    std::unique_ptr<MemoryBuffer> CompiledObjBuffer(
        new SmallVectorMemoryBuffer(std::move(ObjBufferSV)));
  
    // If we have an object cache, tell it about the new object.
    // Note that we're using the compiled image, not the loaded image (as below).
    if (ObjCache) {
      // MemoryBuffer is a thin wrapper around the actual memory, so it's OK
      // to create a temporary object here and delete it after the call.
      MemoryBufferRef MB = CompiledObjBuffer->getMemBufferRef();
      ObjCache->notifyObjectCompiled(M, MB);
    }
  
    return CompiledObjBuffer;
  }
  
  void MCJIT::generateCodeForModule(Module *M) {
    // Get a thread lock to make sure we aren't trying to load multiple times
    MutexGuard locked(lock);
  
    // This must be a module which has already been added to this MCJIT instance.
    assert(OwnedModules.ownsModule(M) &&
           "MCJIT::generateCodeForModule: Unknown module.");
  
    // Re-compilation is not supported
    if (OwnedModules.hasModuleBeenLoaded(M))
      return;
  
    std::unique_ptr<MemoryBuffer> ObjectToLoad;
    // Try to load the pre-compiled object from cache if possible
    if (ObjCache)
      ObjectToLoad = ObjCache->getObject(M);
  
    assert(M->getDataLayout() == getDataLayout() && "DataLayout Mismatch");
  
    // If the cache did not contain a suitable object, compile the object
    if (!ObjectToLoad) {
      ObjectToLoad = emitObject(M);
      assert(ObjectToLoad && "Compilation did not produce an object.");
    }
  
    // Load the object into the dynamic linker.
    // MCJIT now owns the ObjectImage pointer (via its LoadedObjects list).
    Expected<std::unique_ptr<object::ObjectFile>> LoadedObject =
      object::ObjectFile::createObjectFile(ObjectToLoad->getMemBufferRef());
    if (!LoadedObject) {
      std::string Buf;
      raw_string_ostream OS(Buf);
      logAllUnhandledErrors(LoadedObject.takeError(), OS);
      OS.flush();
      report_fatal_error(Buf);
    }
    std::unique_ptr<RuntimeDyld::LoadedObjectInfo> L =
      Dyld.loadObject(*LoadedObject.get());
  
    if (Dyld.hasError())
      report_fatal_error(Dyld.getErrorString());
  
    notifyObjectLoaded(*LoadedObject.get(), *L);
  
    Buffers.push_back(std::move(ObjectToLoad));
    LoadedObjects.push_back(std::move(*LoadedObject));
  
    OwnedModules.markModuleAsLoaded(M);
  }
  
  void MCJIT::finalizeLoadedModules() {
    MutexGuard locked(lock);
  
    // Resolve any outstanding relocations.
    Dyld.resolveRelocations();
  
    OwnedModules.markAllLoadedModulesAsFinalized();
  
    // Register EH frame data for any module we own which has been loaded
    Dyld.registerEHFrames();
  
    // Set page permissions.
    MemMgr->finalizeMemory();
  }
  
  // FIXME: Rename this.
  void MCJIT::finalizeObject() {
    MutexGuard locked(lock);
  
    // Generate code for module is going to move objects out of the 'added' list,
    // so we need to copy that out before using it:
    SmallVector<Module*, 16> ModsToAdd;
    for (auto M : OwnedModules.added())
      ModsToAdd.push_back(M);
  
    for (auto M : ModsToAdd)
      generateCodeForModule(M);
  
    finalizeLoadedModules();
  }
  
  void MCJIT::finalizeModule(Module *M) {
    MutexGuard locked(lock);
  
    // This must be a module which has already been added to this MCJIT instance.
    assert(OwnedModules.ownsModule(M) && "MCJIT::finalizeModule: Unknown module.");
  
    // If the module hasn't been compiled, just do that.
    if (!OwnedModules.hasModuleBeenLoaded(M))
      generateCodeForModule(M);
  
    finalizeLoadedModules();
  }
  
  JITSymbol MCJIT::findExistingSymbol(const std::string &Name) {
    if (void *Addr = getPointerToGlobalIfAvailable(Name))
      return JITSymbol(static_cast<uint64_t>(
                           reinterpret_cast<uintptr_t>(Addr)),
                       JITSymbolFlags::Exported);
  
    return Dyld.getSymbol(Name);
  }
  
  Module *MCJIT::findModuleForSymbol(const std::string &Name,
                                     bool CheckFunctionsOnly) {
    StringRef DemangledName = Name;
    if (DemangledName[0] == getDataLayout().getGlobalPrefix())
      DemangledName = DemangledName.substr(1);
  
    MutexGuard locked(lock);
  
    // If it hasn't already been generated, see if it's in one of our modules.
    for (ModulePtrSet::iterator I = OwnedModules.begin_added(),
                                E = OwnedModules.end_added();
         I != E; ++I) {
      Module *M = *I;
      Function *F = M->getFunction(DemangledName);
      if (F && !F->isDeclaration())
        return M;
      if (!CheckFunctionsOnly) {
        GlobalVariable *G = M->getGlobalVariable(DemangledName);
        if (G && !G->isDeclaration())
          return M;
        // FIXME: Do we need to worry about global aliases?
      }
    }
    // We didn't find the symbol in any of our modules.
    return nullptr;
  }
  
  uint64_t MCJIT::getSymbolAddress(const std::string &Name,
                                   bool CheckFunctionsOnly) {
    std::string MangledName;
    {
      raw_string_ostream MangledNameStream(MangledName);
      Mangler::getNameWithPrefix(MangledNameStream, Name, getDataLayout());
    }
    if (auto Sym = findSymbol(MangledName, CheckFunctionsOnly)) {
      if (auto AddrOrErr = Sym.getAddress())
        return *AddrOrErr;
      else
        report_fatal_error(AddrOrErr.takeError());
    } else if (auto Err = Sym.takeError())
      report_fatal_error(Sym.takeError());
    return 0;
  }
  
  JITSymbol MCJIT::findSymbol(const std::string &Name,
                              bool CheckFunctionsOnly) {
    MutexGuard locked(lock);
  
    // First, check to see if we already have this symbol.
    if (auto Sym = findExistingSymbol(Name))
      return Sym;
  
    for (object::OwningBinary<object::Archive> &OB : Archives) {
      object::Archive *A = OB.getBinary();
      // Look for our symbols in each Archive
      auto OptionalChildOrErr = A->findSym(Name);
      if (!OptionalChildOrErr)
        report_fatal_error(OptionalChildOrErr.takeError());
      auto &OptionalChild = *OptionalChildOrErr;
      if (OptionalChild) {
        // FIXME: Support nested archives?
        Expected<std::unique_ptr<object::Binary>> ChildBinOrErr =
            OptionalChild->getAsBinary();
        if (!ChildBinOrErr) {
          // TODO: Actually report errors helpfully.
          consumeError(ChildBinOrErr.takeError());
          continue;
        }
        std::unique_ptr<object::Binary> &ChildBin = ChildBinOrErr.get();
        if (ChildBin->isObject()) {
          std::unique_ptr<object::ObjectFile> OF(
              static_cast<object::ObjectFile *>(ChildBin.release()));
          // This causes the object file to be loaded.
          addObjectFile(std::move(OF));
          // The address should be here now.
          if (auto Sym = findExistingSymbol(Name))
            return Sym;
        }
      }
    }
  
    // If it hasn't already been generated, see if it's in one of our modules.
    Module *M = findModuleForSymbol(Name, CheckFunctionsOnly);
    if (M) {
      generateCodeForModule(M);
  
      // Check the RuntimeDyld table again, it should be there now.
      return findExistingSymbol(Name);
    }
  
    // If a LazyFunctionCreator is installed, use it to get/create the function.
    // FIXME: Should we instead have a LazySymbolCreator callback?
    if (LazyFunctionCreator) {
      auto Addr = static_cast<uint64_t>(
                    reinterpret_cast<uintptr_t>(LazyFunctionCreator(Name)));
      return JITSymbol(Addr, JITSymbolFlags::Exported);
    }
  
    return nullptr;
  }
  
  uint64_t MCJIT::getGlobalValueAddress(const std::string &Name) {
    MutexGuard locked(lock);
    uint64_t Result = getSymbolAddress(Name, false);
    if (Result != 0)
      finalizeLoadedModules();
    return Result;
  }
  
  uint64_t MCJIT::getFunctionAddress(const std::string &Name) {
    MutexGuard locked(lock);
    uint64_t Result = getSymbolAddress(Name, true);
    if (Result != 0)
      finalizeLoadedModules();
    return Result;
  }
  
  // Deprecated.  Use getFunctionAddress instead.
  void *MCJIT::getPointerToFunction(Function *F) {
    MutexGuard locked(lock);
  
    Mangler Mang;
    SmallString<128> Name;
    TM->getNameWithPrefix(Name, F, Mang);
  
    if (F->isDeclaration() || F->hasAvailableExternallyLinkage()) {
      bool AbortOnFailure = !F->hasExternalWeakLinkage();
      void *Addr = getPointerToNamedFunction(Name, AbortOnFailure);
      updateGlobalMapping(F, Addr);
      return Addr;
    }
  
    Module *M = F->getParent();
    bool HasBeenAddedButNotLoaded = OwnedModules.hasModuleBeenAddedButNotLoaded(M);
  
    // Make sure the relevant module has been compiled and loaded.
    if (HasBeenAddedButNotLoaded)
      generateCodeForModule(M);
    else if (!OwnedModules.hasModuleBeenLoaded(M)) {
      // If this function doesn't belong to one of our modules, we're done.
      // FIXME: Asking for the pointer to a function that hasn't been registered,
      //        and isn't a declaration (which is handled above) should probably
      //        be an assertion.
      return nullptr;
    }
  
    // FIXME: Should the Dyld be retaining module information? Probably not.
    //
    // This is the accessor for the target address, so make sure to check the
    // load address of the symbol, not the local address.
    return (void*)Dyld.getSymbol(Name).getAddress();
  }
  
  void MCJIT::runStaticConstructorsDestructorsInModulePtrSet(
      bool isDtors, ModulePtrSet::iterator I, ModulePtrSet::iterator E) {
    for (; I != E; ++I) {
      ExecutionEngine::runStaticConstructorsDestructors(**I, isDtors);
    }
  }
  
  void MCJIT::runStaticConstructorsDestructors(bool isDtors) {
    // Execute global ctors/dtors for each module in the program.
    runStaticConstructorsDestructorsInModulePtrSet(
        isDtors, OwnedModules.begin_added(), OwnedModules.end_added());
    runStaticConstructorsDestructorsInModulePtrSet(
        isDtors, OwnedModules.begin_loaded(), OwnedModules.end_loaded());
    runStaticConstructorsDestructorsInModulePtrSet(
        isDtors, OwnedModules.begin_finalized(), OwnedModules.end_finalized());
  }
  
  Function *MCJIT::FindFunctionNamedInModulePtrSet(StringRef FnName,
                                                   ModulePtrSet::iterator I,
                                                   ModulePtrSet::iterator E) {
    for (; I != E; ++I) {
      Function *F = (*I)->getFunction(FnName);
      if (F && !F->isDeclaration())
        return F;
    }
    return nullptr;
  }
  
  GlobalVariable *MCJIT::FindGlobalVariableNamedInModulePtrSet(StringRef Name,
                                                               bool AllowInternal,
                                                               ModulePtrSet::iterator I,
                                                               ModulePtrSet::iterator E) {
    for (; I != E; ++I) {
      GlobalVariable *GV = (*I)->getGlobalVariable(Name, AllowInternal);
      if (GV && !GV->isDeclaration())
        return GV;
    }
    return nullptr;
  }
  
  
  Function *MCJIT::FindFunctionNamed(StringRef FnName) {
    Function *F = FindFunctionNamedInModulePtrSet(
        FnName, OwnedModules.begin_added(), OwnedModules.end_added());
    if (!F)
      F = FindFunctionNamedInModulePtrSet(FnName, OwnedModules.begin_loaded(),
                                          OwnedModules.end_loaded());
    if (!F)
      F = FindFunctionNamedInModulePtrSet(FnName, OwnedModules.begin_finalized(),
                                          OwnedModules.end_finalized());
    return F;
  }
  
  GlobalVariable *MCJIT::FindGlobalVariableNamed(StringRef Name, bool AllowInternal) {
    GlobalVariable *GV = FindGlobalVariableNamedInModulePtrSet(
        Name, AllowInternal, OwnedModules.begin_added(), OwnedModules.end_added());
    if (!GV)
      GV = FindGlobalVariableNamedInModulePtrSet(Name, AllowInternal, OwnedModules.begin_loaded(),
                                          OwnedModules.end_loaded());
    if (!GV)
      GV = FindGlobalVariableNamedInModulePtrSet(Name, AllowInternal, OwnedModules.begin_finalized(),
                                          OwnedModules.end_finalized());
    return GV;
  }
  
  GenericValue MCJIT::runFunction(Function *F, ArrayRef<GenericValue> ArgValues) {
    assert(F && "Function *F was null at entry to run()");
  
    void *FPtr = getPointerToFunction(F);
    finalizeModule(F->getParent());
    assert(FPtr && "Pointer to fn's code was null after getPointerToFunction");
    FunctionType *FTy = F->getFunctionType();
    Type *RetTy = FTy->getReturnType();
  
    assert((FTy->getNumParams() == ArgValues.size() ||
            (FTy->isVarArg() && FTy->getNumParams() <= ArgValues.size())) &&
           "Wrong number of arguments passed into function!");
    assert(FTy->getNumParams() == ArgValues.size() &&
           "This doesn't support passing arguments through varargs (yet)!");
  
    // Handle some common cases first.  These cases correspond to common `main'
    // prototypes.
    if (RetTy->isIntegerTy(32) || RetTy->isVoidTy()) {
      switch (ArgValues.size()) {
      case 3:
        if (FTy->getParamType(0)->isIntegerTy(32) &&
            FTy->getParamType(1)->isPointerTy() &&
            FTy->getParamType(2)->isPointerTy()) {
          int (*PF)(int, char **, const char **) =
            (int(*)(int, char **, const char **))(intptr_t)FPtr;
  
          // Call the function.
          GenericValue rv;
          rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue(),
                                   (char **)GVTOP(ArgValues[1]),
                                   (const char **)GVTOP(ArgValues[2])));
          return rv;
        }
        break;
      case 2:
        if (FTy->getParamType(0)->isIntegerTy(32) &&
            FTy->getParamType(1)->isPointerTy()) {
          int (*PF)(int, char **) = (int(*)(int, char **))(intptr_t)FPtr;
  
          // Call the function.
          GenericValue rv;
          rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue(),
                                   (char **)GVTOP(ArgValues[1])));
          return rv;
        }
        break;
      case 1:
        if (FTy->getNumParams() == 1 &&
            FTy->getParamType(0)->isIntegerTy(32)) {
          GenericValue rv;
          int (*PF)(int) = (int(*)(int))(intptr_t)FPtr;
          rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue()));
          return rv;
        }
        break;
      }
    }
  
    // Handle cases where no arguments are passed first.
    if (ArgValues.empty()) {
      GenericValue rv;
      switch (RetTy->getTypeID()) {
      default: llvm_unreachable("Unknown return type for function call!");
      case Type::IntegerTyID: {
        unsigned BitWidth = cast<IntegerType>(RetTy)->getBitWidth();
        if (BitWidth == 1)
          rv.IntVal = APInt(BitWidth, ((bool(*)())(intptr_t)FPtr)());
        else if (BitWidth <= 8)
          rv.IntVal = APInt(BitWidth, ((char(*)())(intptr_t)FPtr)());
        else if (BitWidth <= 16)
          rv.IntVal = APInt(BitWidth, ((short(*)())(intptr_t)FPtr)());
        else if (BitWidth <= 32)
          rv.IntVal = APInt(BitWidth, ((int(*)())(intptr_t)FPtr)());
        else if (BitWidth <= 64)
          rv.IntVal = APInt(BitWidth, ((int64_t(*)())(intptr_t)FPtr)());
        else
          llvm_unreachable("Integer types > 64 bits not supported");
        return rv;
      }
      case Type::VoidTyID:
        rv.IntVal = APInt(32, ((int(*)())(intptr_t)FPtr)());
        return rv;
      case Type::FloatTyID:
        rv.FloatVal = ((float(*)())(intptr_t)FPtr)();
        return rv;
      case Type::DoubleTyID:
        rv.DoubleVal = ((double(*)())(intptr_t)FPtr)();
        return rv;
      case Type::X86_FP80TyID:
      case Type::FP128TyID:
      case Type::PPC_FP128TyID:
        llvm_unreachable("long double not supported yet");
      case Type::PointerTyID:
        return PTOGV(((void*(*)())(intptr_t)FPtr)());
      }
    }
  
    report_fatal_error("MCJIT::runFunction does not support full-featured "
                       "argument passing. Please use "
                       "ExecutionEngine::getFunctionAddress and cast the result "
                       "to the desired function pointer type.");
  }
  
  void *MCJIT::getPointerToNamedFunction(StringRef Name, bool AbortOnFailure) {
    if (!isSymbolSearchingDisabled()) {
      if (auto Sym = Resolver.findSymbol(Name)) {
        if (auto AddrOrErr = Sym.getAddress())
          return reinterpret_cast<void*>(
                   static_cast<uintptr_t>(*AddrOrErr));
      } else if (auto Err = Sym.takeError())
        report_fatal_error(std::move(Err));
    }
  
    /// If a LazyFunctionCreator is installed, use it to get/create the function.
    if (LazyFunctionCreator)
      if (void *RP = LazyFunctionCreator(Name))
        return RP;
  
    if (AbortOnFailure) {
      report_fatal_error("Program used external function '"+Name+
                         "' which could not be resolved!");
    }
    return nullptr;
  }
  
  void MCJIT::RegisterJITEventListener(JITEventListener *L) {
    if (!L)
      return;
    MutexGuard locked(lock);
    EventListeners.push_back(L);
  }
  
  void MCJIT::UnregisterJITEventListener(JITEventListener *L) {
    if (!L)
      return;
    MutexGuard locked(lock);
    auto I = find(reverse(EventListeners), L);
    if (I != EventListeners.rend()) {
      std::swap(*I, EventListeners.back());
      EventListeners.pop_back();
    }
  }
  
  void MCJIT::notifyObjectLoaded(const object::ObjectFile &Obj,
                                 const RuntimeDyld::LoadedObjectInfo &L) {
    uint64_t Key =
        static_cast<uint64_t>(reinterpret_cast<uintptr_t>(Obj.getData().data()));
    MutexGuard locked(lock);
    MemMgr->notifyObjectLoaded(this, Obj);
    for (unsigned I = 0, S = EventListeners.size(); I < S; ++I) {
      EventListeners[I]->notifyObjectLoaded(Key, Obj, L);
    }
  }
  
  void MCJIT::notifyFreeingObject(const object::ObjectFile &Obj) {
    uint64_t Key =
        static_cast<uint64_t>(reinterpret_cast<uintptr_t>(Obj.getData().data()));
    MutexGuard locked(lock);
    for (JITEventListener *L : EventListeners)
      L->notifyFreeingObject(Key);
  }
  
  JITSymbol
  LinkingSymbolResolver::findSymbol(const std::string &Name) {
    auto Result = ParentEngine.findSymbol(Name, false);
    if (Result)
      return Result;
    if (ParentEngine.isSymbolSearchingDisabled())
      return nullptr;
    return ClientResolver->findSymbol(Name);
  }
  
  void LinkingSymbolResolver::anchor() {}
  