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1//===-- MCJIT.cpp - MC-based Just-in-Time Compiler ------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "MCJIT.h"10#include "llvm/ADT/STLExtras.h"11#include "llvm/ExecutionEngine/GenericValue.h"12#include "llvm/ExecutionEngine/JITEventListener.h"13#include "llvm/ExecutionEngine/MCJIT.h"14#include "llvm/ExecutionEngine/ObjectCache.h"15#include "llvm/ExecutionEngine/SectionMemoryManager.h"16#include "llvm/IR/DataLayout.h"17#include "llvm/IR/DerivedTypes.h"18#include "llvm/IR/Function.h"19#include "llvm/IR/LegacyPassManager.h"20#include "llvm/IR/Mangler.h"21#include "llvm/IR/Module.h"22#include "llvm/Object/Archive.h"23#include "llvm/Object/ObjectFile.h"24#include "llvm/Support/DynamicLibrary.h"25#include "llvm/Support/ErrorHandling.h"26#include "llvm/Support/MemoryBuffer.h"27#include "llvm/Support/SmallVectorMemoryBuffer.h"28#include <mutex>29 30using namespace llvm;31 32namespace {33 34static struct RegisterJIT {35  RegisterJIT() { MCJIT::Register(); }36} JITRegistrator;37 38}39 40extern "C" void LLVMLinkInMCJIT() {41}42 43ExecutionEngine *44MCJIT::createJIT(std::unique_ptr<Module> M, std::string *ErrorStr,45                 std::shared_ptr<MCJITMemoryManager> MemMgr,46                 std::shared_ptr<LegacyJITSymbolResolver> Resolver,47                 std::unique_ptr<TargetMachine> TM) {48  // Try to register the program as a source of symbols to resolve against.49  //50  // FIXME: Don't do this here.51  sys::DynamicLibrary::LoadLibraryPermanently(nullptr, nullptr);52 53  if (!MemMgr || !Resolver) {54    auto RTDyldMM = std::make_shared<SectionMemoryManager>();55    if (!MemMgr)56      MemMgr = RTDyldMM;57    if (!Resolver)58      Resolver = RTDyldMM;59  }60 61  return new MCJIT(std::move(M), std::move(TM), std::move(MemMgr),62                   std::move(Resolver));63}64 65MCJIT::MCJIT(std::unique_ptr<Module> M, std::unique_ptr<TargetMachine> TM,66             std::shared_ptr<MCJITMemoryManager> MemMgr,67             std::shared_ptr<LegacyJITSymbolResolver> Resolver)68    : ExecutionEngine(TM->createDataLayout(), std::move(M)), TM(std::move(TM)),69      Ctx(nullptr), MemMgr(std::move(MemMgr)),70      Resolver(*this, std::move(Resolver)), Dyld(*this->MemMgr, this->Resolver),71      ObjCache(nullptr) {72  // FIXME: We are managing our modules, so we do not want the base class73  // ExecutionEngine to manage them as well. To avoid double destruction74  // of the first (and only) module added in ExecutionEngine constructor75  // we remove it from EE and will destruct it ourselves.76  //77  // It may make sense to move our module manager (based on SmallStPtr) back78  // into EE if the JIT and Interpreter can live with it.79  // If so, additional functions: addModule, removeModule, FindFunctionNamed,80  // runStaticConstructorsDestructors could be moved back to EE as well.81  //82  std::unique_ptr<Module> First = std::move(Modules[0]);83  Modules.clear();84 85  if (First->getDataLayout().isDefault())86    First->setDataLayout(getDataLayout());87 88  OwnedModules.addModule(std::move(First));89  RegisterJITEventListener(JITEventListener::createGDBRegistrationListener());90}91 92MCJIT::~MCJIT() {93  std::lock_guard<sys::Mutex> locked(lock);94 95  Dyld.deregisterEHFrames();96 97  for (auto &Obj : LoadedObjects)98    if (Obj)99      notifyFreeingObject(*Obj);100 101  Archives.clear();102}103 104void MCJIT::addModule(std::unique_ptr<Module> M) {105  std::lock_guard<sys::Mutex> locked(lock);106 107  if (M->getDataLayout().isDefault())108    M->setDataLayout(getDataLayout());109 110  OwnedModules.addModule(std::move(M));111}112 113bool MCJIT::removeModule(Module *M) {114  std::lock_guard<sys::Mutex> locked(lock);115  return OwnedModules.removeModule(M);116}117 118void MCJIT::addObjectFile(std::unique_ptr<object::ObjectFile> Obj) {119  std::unique_ptr<RuntimeDyld::LoadedObjectInfo> L = Dyld.loadObject(*Obj);120  if (Dyld.hasError())121    report_fatal_error(Dyld.getErrorString());122 123  notifyObjectLoaded(*Obj, *L);124 125  LoadedObjects.push_back(std::move(Obj));126}127 128void MCJIT::addObjectFile(object::OwningBinary<object::ObjectFile> Obj) {129  std::unique_ptr<object::ObjectFile> ObjFile;130  std::unique_ptr<MemoryBuffer> MemBuf;131  std::tie(ObjFile, MemBuf) = Obj.takeBinary();132  addObjectFile(std::move(ObjFile));133  Buffers.push_back(std::move(MemBuf));134}135 136void MCJIT::addArchive(object::OwningBinary<object::Archive> A) {137  Archives.push_back(std::move(A));138}139 140void MCJIT::setObjectCache(ObjectCache* NewCache) {141  std::lock_guard<sys::Mutex> locked(lock);142  ObjCache = NewCache;143}144 145std::unique_ptr<MemoryBuffer> MCJIT::emitObject(Module *M) {146  assert(M && "Can not emit a null module");147 148  std::lock_guard<sys::Mutex> locked(lock);149 150  // Materialize all globals in the module if they have not been151  // materialized already.152  cantFail(M->materializeAll());153 154  // This must be a module which has already been added but not loaded to this155  // MCJIT instance, since these conditions are tested by our caller,156  // generateCodeForModule.157 158  legacy::PassManager PM;159 160  // The RuntimeDyld will take ownership of this shortly161  SmallVector<char, 4096> ObjBufferSV;162  raw_svector_ostream ObjStream(ObjBufferSV);163 164  // Turn the machine code intermediate representation into bytes in memory165  // that may be executed.166  if (TM->addPassesToEmitMC(PM, Ctx, ObjStream, !getVerifyModules()))167    report_fatal_error("Target does not support MC emission!");168 169  // Initialize passes.170  PM.run(*M);171  // Flush the output buffer to get the generated code into memory172 173  auto CompiledObjBuffer = std::make_unique<SmallVectorMemoryBuffer>(174      std::move(ObjBufferSV), /*RequiresNullTerminator=*/false);175 176  // If we have an object cache, tell it about the new object.177  // Note that we're using the compiled image, not the loaded image (as below).178  if (ObjCache) {179    // MemoryBuffer is a thin wrapper around the actual memory, so it's OK180    // to create a temporary object here and delete it after the call.181    MemoryBufferRef MB = CompiledObjBuffer->getMemBufferRef();182    ObjCache->notifyObjectCompiled(M, MB);183  }184 185  return CompiledObjBuffer;186}187 188void MCJIT::generateCodeForModule(Module *M) {189  // Get a thread lock to make sure we aren't trying to load multiple times190  std::lock_guard<sys::Mutex> locked(lock);191 192  // This must be a module which has already been added to this MCJIT instance.193  assert(OwnedModules.ownsModule(M) &&194         "MCJIT::generateCodeForModule: Unknown module.");195 196  // Re-compilation is not supported197  if (OwnedModules.hasModuleBeenLoaded(M))198    return;199 200  std::unique_ptr<MemoryBuffer> ObjectToLoad;201  // Try to load the pre-compiled object from cache if possible202  if (ObjCache)203    ObjectToLoad = ObjCache->getObject(M);204 205  assert(M->getDataLayout() == getDataLayout() && "DataLayout Mismatch");206 207  // If the cache did not contain a suitable object, compile the object208  if (!ObjectToLoad) {209    ObjectToLoad = emitObject(M);210    assert(ObjectToLoad && "Compilation did not produce an object.");211  }212 213  // Load the object into the dynamic linker.214  // MCJIT now owns the ObjectImage pointer (via its LoadedObjects list).215  Expected<std::unique_ptr<object::ObjectFile>> LoadedObject =216    object::ObjectFile::createObjectFile(ObjectToLoad->getMemBufferRef());217  if (!LoadedObject) {218    std::string Buf;219    raw_string_ostream OS(Buf);220    logAllUnhandledErrors(LoadedObject.takeError(), OS);221    report_fatal_error(Twine(Buf));222  }223  std::unique_ptr<RuntimeDyld::LoadedObjectInfo> L =224    Dyld.loadObject(*LoadedObject.get());225 226  if (Dyld.hasError())227    report_fatal_error(Dyld.getErrorString());228 229  notifyObjectLoaded(*LoadedObject.get(), *L);230 231  Buffers.push_back(std::move(ObjectToLoad));232  LoadedObjects.push_back(std::move(*LoadedObject));233 234  OwnedModules.markModuleAsLoaded(M);235}236 237void MCJIT::finalizeLoadedModules() {238  std::lock_guard<sys::Mutex> locked(lock);239 240  // Resolve any outstanding relocations.241  Dyld.resolveRelocations();242 243  // Check for Dyld error.244  if (Dyld.hasError())245    ErrMsg = Dyld.getErrorString().str();246 247  OwnedModules.markAllLoadedModulesAsFinalized();248 249  // Register EH frame data for any module we own which has been loaded250  Dyld.registerEHFrames();251 252  // Set page permissions.253  MemMgr->finalizeMemory();254}255 256// FIXME: Rename this.257void MCJIT::finalizeObject() {258  std::lock_guard<sys::Mutex> locked(lock);259 260  // Generate code for module is going to move objects out of the 'added' list,261  // so we need to copy that out before using it:262  SmallVector<Module *, 16> ModsToAdd(OwnedModules.added());263 264  for (auto *M : ModsToAdd)265    generateCodeForModule(M);266 267  finalizeLoadedModules();268}269 270void MCJIT::finalizeModule(Module *M) {271  std::lock_guard<sys::Mutex> locked(lock);272 273  // This must be a module which has already been added to this MCJIT instance.274  assert(OwnedModules.ownsModule(M) && "MCJIT::finalizeModule: Unknown module.");275 276  // If the module hasn't been compiled, just do that.277  if (!OwnedModules.hasModuleBeenLoaded(M))278    generateCodeForModule(M);279 280  finalizeLoadedModules();281}282 283JITSymbol MCJIT::findExistingSymbol(const std::string &Name) {284  if (void *Addr = getPointerToGlobalIfAvailable(Name))285    return JITSymbol(static_cast<uint64_t>(286                         reinterpret_cast<uintptr_t>(Addr)),287                     JITSymbolFlags::Exported);288 289  return Dyld.getSymbol(Name);290}291 292Module *MCJIT::findModuleForSymbol(const std::string &Name,293                                   bool CheckFunctionsOnly) {294  StringRef DemangledName = Name;295  if (DemangledName[0] == getDataLayout().getGlobalPrefix())296    DemangledName = DemangledName.substr(1);297 298  std::lock_guard<sys::Mutex> locked(lock);299 300  // If it hasn't already been generated, see if it's in one of our modules.301  for (ModulePtrSet::iterator I = OwnedModules.begin_added(),302                              E = OwnedModules.end_added();303       I != E; ++I) {304    Module *M = *I;305    Function *F = M->getFunction(DemangledName);306    if (F && !F->isDeclaration())307      return M;308    if (!CheckFunctionsOnly) {309      GlobalVariable *G = M->getGlobalVariable(DemangledName);310      if (G && !G->isDeclaration())311        return M;312      // FIXME: Do we need to worry about global aliases?313    }314  }315  // We didn't find the symbol in any of our modules.316  return nullptr;317}318 319uint64_t MCJIT::getSymbolAddress(const std::string &Name,320                                 bool CheckFunctionsOnly) {321  std::string MangledName;322  {323    raw_string_ostream MangledNameStream(MangledName);324    Mangler::getNameWithPrefix(MangledNameStream, Name, getDataLayout());325  }326  if (auto Sym = findSymbol(MangledName, CheckFunctionsOnly)) {327    if (auto AddrOrErr = Sym.getAddress())328      return *AddrOrErr;329    else330      report_fatal_error(AddrOrErr.takeError());331  } else if (auto Err = Sym.takeError())332    report_fatal_error(Sym.takeError());333  return 0;334}335 336JITSymbol MCJIT::findSymbol(const std::string &Name,337                            bool CheckFunctionsOnly) {338  std::lock_guard<sys::Mutex> locked(lock);339 340  // First, check to see if we already have this symbol.341  if (auto Sym = findExistingSymbol(Name))342    return Sym;343 344  for (object::OwningBinary<object::Archive> &OB : Archives) {345    object::Archive *A = OB.getBinary();346    // Look for our symbols in each Archive347    auto OptionalChildOrErr = A->findSym(Name);348    if (!OptionalChildOrErr)349      report_fatal_error(OptionalChildOrErr.takeError());350    auto &OptionalChild = *OptionalChildOrErr;351    if (OptionalChild) {352      // FIXME: Support nested archives?353      Expected<std::unique_ptr<object::Binary>> ChildBinOrErr =354          OptionalChild->getAsBinary();355      if (!ChildBinOrErr) {356        // TODO: Actually report errors helpfully.357        consumeError(ChildBinOrErr.takeError());358        continue;359      }360      std::unique_ptr<object::Binary> &ChildBin = ChildBinOrErr.get();361      if (ChildBin->isObject()) {362        std::unique_ptr<object::ObjectFile> OF(363            static_cast<object::ObjectFile *>(ChildBin.release()));364        // This causes the object file to be loaded.365        addObjectFile(std::move(OF));366        // The address should be here now.367        if (auto Sym = findExistingSymbol(Name))368          return Sym;369      }370    }371  }372 373  // If it hasn't already been generated, see if it's in one of our modules.374  Module *M = findModuleForSymbol(Name, CheckFunctionsOnly);375  if (M) {376    generateCodeForModule(M);377 378    // Check the RuntimeDyld table again, it should be there now.379    return findExistingSymbol(Name);380  }381 382  // If a LazyFunctionCreator is installed, use it to get/create the function.383  // FIXME: Should we instead have a LazySymbolCreator callback?384  if (LazyFunctionCreator) {385    auto Addr = static_cast<uint64_t>(386                  reinterpret_cast<uintptr_t>(LazyFunctionCreator(Name)));387    return JITSymbol(Addr, JITSymbolFlags::Exported);388  }389 390  return nullptr;391}392 393uint64_t MCJIT::getGlobalValueAddress(const std::string &Name) {394  std::lock_guard<sys::Mutex> locked(lock);395  uint64_t Result = getSymbolAddress(Name, false);396  if (Result != 0)397    finalizeLoadedModules();398  return Result;399}400 401uint64_t MCJIT::getFunctionAddress(const std::string &Name) {402  std::lock_guard<sys::Mutex> locked(lock);403  uint64_t Result = getSymbolAddress(Name, true);404  if (Result != 0)405    finalizeLoadedModules();406  return Result;407}408 409// Deprecated.  Use getFunctionAddress instead.410void *MCJIT::getPointerToFunction(Function *F) {411  std::lock_guard<sys::Mutex> locked(lock);412 413  Mangler Mang;414  SmallString<128> Name;415  TM->getNameWithPrefix(Name, F, Mang);416 417  if (F->isDeclaration() || F->hasAvailableExternallyLinkage()) {418    bool AbortOnFailure = !F->hasExternalWeakLinkage();419    void *Addr = getPointerToNamedFunction(Name, AbortOnFailure);420    updateGlobalMapping(F, Addr);421    return Addr;422  }423 424  Module *M = F->getParent();425  bool HasBeenAddedButNotLoaded = OwnedModules.hasModuleBeenAddedButNotLoaded(M);426 427  // Make sure the relevant module has been compiled and loaded.428  if (HasBeenAddedButNotLoaded)429    generateCodeForModule(M);430  else if (!OwnedModules.hasModuleBeenLoaded(M)) {431    // If this function doesn't belong to one of our modules, we're done.432    // FIXME: Asking for the pointer to a function that hasn't been registered,433    //        and isn't a declaration (which is handled above) should probably434    //        be an assertion.435    return nullptr;436  }437 438  // FIXME: Should the Dyld be retaining module information? Probably not.439  //440  // This is the accessor for the target address, so make sure to check the441  // load address of the symbol, not the local address.442  return (void*)Dyld.getSymbol(Name).getAddress();443}444 445void MCJIT::runStaticConstructorsDestructorsInModulePtrSet(446    bool isDtors, ModulePtrSet::iterator I, ModulePtrSet::iterator E) {447  for (; I != E; ++I) {448    ExecutionEngine::runStaticConstructorsDestructors(**I, isDtors);449  }450}451 452void MCJIT::runStaticConstructorsDestructors(bool isDtors) {453  // Execute global ctors/dtors for each module in the program.454  runStaticConstructorsDestructorsInModulePtrSet(455      isDtors, OwnedModules.begin_added(), OwnedModules.end_added());456  runStaticConstructorsDestructorsInModulePtrSet(457      isDtors, OwnedModules.begin_loaded(), OwnedModules.end_loaded());458  runStaticConstructorsDestructorsInModulePtrSet(459      isDtors, OwnedModules.begin_finalized(), OwnedModules.end_finalized());460}461 462Function *MCJIT::FindFunctionNamedInModulePtrSet(StringRef FnName,463                                                 ModulePtrSet::iterator I,464                                                 ModulePtrSet::iterator E) {465  for (; I != E; ++I) {466    Function *F = (*I)->getFunction(FnName);467    if (F && !F->isDeclaration())468      return F;469  }470  return nullptr;471}472 473GlobalVariable *MCJIT::FindGlobalVariableNamedInModulePtrSet(StringRef Name,474                                                             bool AllowInternal,475                                                             ModulePtrSet::iterator I,476                                                             ModulePtrSet::iterator E) {477  for (; I != E; ++I) {478    GlobalVariable *GV = (*I)->getGlobalVariable(Name, AllowInternal);479    if (GV && !GV->isDeclaration())480      return GV;481  }482  return nullptr;483}484 485 486Function *MCJIT::FindFunctionNamed(StringRef FnName) {487  Function *F = FindFunctionNamedInModulePtrSet(488      FnName, OwnedModules.begin_added(), OwnedModules.end_added());489  if (!F)490    F = FindFunctionNamedInModulePtrSet(FnName, OwnedModules.begin_loaded(),491                                        OwnedModules.end_loaded());492  if (!F)493    F = FindFunctionNamedInModulePtrSet(FnName, OwnedModules.begin_finalized(),494                                        OwnedModules.end_finalized());495  return F;496}497 498GlobalVariable *MCJIT::FindGlobalVariableNamed(StringRef Name, bool AllowInternal) {499  GlobalVariable *GV = FindGlobalVariableNamedInModulePtrSet(500      Name, AllowInternal, OwnedModules.begin_added(), OwnedModules.end_added());501  if (!GV)502    GV = FindGlobalVariableNamedInModulePtrSet(Name, AllowInternal, OwnedModules.begin_loaded(),503                                        OwnedModules.end_loaded());504  if (!GV)505    GV = FindGlobalVariableNamedInModulePtrSet(Name, AllowInternal, OwnedModules.begin_finalized(),506                                        OwnedModules.end_finalized());507  return GV;508}509 510GenericValue MCJIT::runFunction(Function *F, ArrayRef<GenericValue> ArgValues) {511  assert(F && "Function *F was null at entry to run()");512 513  void *FPtr = getPointerToFunction(F);514  finalizeModule(F->getParent());515  assert(FPtr && "Pointer to fn's code was null after getPointerToFunction");516  FunctionType *FTy = F->getFunctionType();517  Type *RetTy = FTy->getReturnType();518 519  assert((FTy->getNumParams() == ArgValues.size() ||520          (FTy->isVarArg() && FTy->getNumParams() <= ArgValues.size())) &&521         "Wrong number of arguments passed into function!");522  assert(FTy->getNumParams() == ArgValues.size() &&523         "This doesn't support passing arguments through varargs (yet)!");524 525  // Handle some common cases first.  These cases correspond to common `main'526  // prototypes.527  if (RetTy->isIntegerTy(32) || RetTy->isVoidTy()) {528    switch (ArgValues.size()) {529    case 3:530      if (FTy->getParamType(0)->isIntegerTy(32) &&531          FTy->getParamType(1)->isPointerTy() &&532          FTy->getParamType(2)->isPointerTy()) {533        int (*PF)(int, char **, const char **) =534          (int(*)(int, char **, const char **))(intptr_t)FPtr;535 536        // Call the function.537        GenericValue rv;538        rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue(),539                                 (char **)GVTOP(ArgValues[1]),540                                 (const char **)GVTOP(ArgValues[2])));541        return rv;542      }543      break;544    case 2:545      if (FTy->getParamType(0)->isIntegerTy(32) &&546          FTy->getParamType(1)->isPointerTy()) {547        int (*PF)(int, char **) = (int(*)(int, char **))(intptr_t)FPtr;548 549        // Call the function.550        GenericValue rv;551        rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue(),552                                 (char **)GVTOP(ArgValues[1])));553        return rv;554      }555      break;556    case 1:557      if (FTy->getNumParams() == 1 &&558          FTy->getParamType(0)->isIntegerTy(32)) {559        GenericValue rv;560        int (*PF)(int) = (int(*)(int))(intptr_t)FPtr;561        rv.IntVal = APInt(32, PF(ArgValues[0].IntVal.getZExtValue()));562        return rv;563      }564      break;565    }566  }567 568  // Handle cases where no arguments are passed first.569  if (ArgValues.empty()) {570    GenericValue rv;571    switch (RetTy->getTypeID()) {572    default: llvm_unreachable("Unknown return type for function call!");573    case Type::IntegerTyID: {574      unsigned BitWidth = cast<IntegerType>(RetTy)->getBitWidth();575      if (BitWidth == 1)576        rv.IntVal = APInt(BitWidth, ((bool(*)())(intptr_t)FPtr)());577      else if (BitWidth <= 8)578        rv.IntVal = APInt(BitWidth, ((char(*)())(intptr_t)FPtr)());579      else if (BitWidth <= 16)580        rv.IntVal = APInt(BitWidth, ((short(*)())(intptr_t)FPtr)());581      else if (BitWidth <= 32)582        rv.IntVal = APInt(BitWidth, ((int(*)())(intptr_t)FPtr)());583      else if (BitWidth <= 64)584        rv.IntVal = APInt(BitWidth, ((int64_t(*)())(intptr_t)FPtr)());585      else586        llvm_unreachable("Integer types > 64 bits not supported");587      return rv;588    }589    case Type::VoidTyID:590      rv.IntVal = APInt(32, ((int (*)())(intptr_t)FPtr)(), true);591      return rv;592    case Type::FloatTyID:593      rv.FloatVal = ((float(*)())(intptr_t)FPtr)();594      return rv;595    case Type::DoubleTyID:596      rv.DoubleVal = ((double(*)())(intptr_t)FPtr)();597      return rv;598    case Type::X86_FP80TyID:599    case Type::FP128TyID:600    case Type::PPC_FP128TyID:601      llvm_unreachable("long double not supported yet");602    case Type::PointerTyID:603      return PTOGV(((void*(*)())(intptr_t)FPtr)());604    }605  }606 607  report_fatal_error("MCJIT::runFunction does not support full-featured "608                     "argument passing. Please use "609                     "ExecutionEngine::getFunctionAddress and cast the result "610                     "to the desired function pointer type.");611}612 613void *MCJIT::getPointerToNamedFunction(StringRef Name, bool AbortOnFailure) {614  if (!isSymbolSearchingDisabled()) {615    if (auto Sym = Resolver.findSymbol(std::string(Name))) {616      if (auto AddrOrErr = Sym.getAddress())617        return reinterpret_cast<void*>(618                 static_cast<uintptr_t>(*AddrOrErr));619    } else if (auto Err = Sym.takeError())620      report_fatal_error(std::move(Err));621  }622 623  /// If a LazyFunctionCreator is installed, use it to get/create the function.624  if (LazyFunctionCreator)625    if (void *RP = LazyFunctionCreator(std::string(Name)))626      return RP;627 628  if (AbortOnFailure) {629    report_fatal_error("Program used external function '"+Name+630                       "' which could not be resolved!");631  }632  return nullptr;633}634 635void MCJIT::RegisterJITEventListener(JITEventListener *L) {636  if (!L)637    return;638  std::lock_guard<sys::Mutex> locked(lock);639  EventListeners.push_back(L);640}641 642void MCJIT::UnregisterJITEventListener(JITEventListener *L) {643  if (!L)644    return;645  std::lock_guard<sys::Mutex> locked(lock);646  auto I = find(reverse(EventListeners), L);647  if (I != EventListeners.rend()) {648    std::swap(*I, EventListeners.back());649    EventListeners.pop_back();650  }651}652 653void MCJIT::notifyObjectLoaded(const object::ObjectFile &Obj,654                               const RuntimeDyld::LoadedObjectInfo &L) {655  uint64_t Key =656      static_cast<uint64_t>(reinterpret_cast<uintptr_t>(Obj.getData().data()));657  std::lock_guard<sys::Mutex> locked(lock);658  MemMgr->notifyObjectLoaded(this, Obj);659  for (JITEventListener *EL : EventListeners)660    EL->notifyObjectLoaded(Key, Obj, L);661}662 663void MCJIT::notifyFreeingObject(const object::ObjectFile &Obj) {664  uint64_t Key =665      static_cast<uint64_t>(reinterpret_cast<uintptr_t>(Obj.getData().data()));666  std::lock_guard<sys::Mutex> locked(lock);667  for (JITEventListener *L : EventListeners)668    L->notifyFreeingObject(Key);669}670 671JITSymbol672LinkingSymbolResolver::findSymbol(const std::string &Name) {673  auto Result = ParentEngine.findSymbol(Name, false);674  if (Result)675    return Result;676  if (ParentEngine.isSymbolSearchingDisabled())677    return nullptr;678  return ClientResolver->findSymbol(Name);679}680 681void LinkingSymbolResolver::anchor() {}682