lib/ExecutionEngine/MCJIT/MCJIT.cpp - llvm - Git at Google

 //===-- 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() {}
	//===-- 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() {}