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//===-- MCJIT.h - Class definition for the MCJIT ----------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ExecutionEngine/ExecutionEngine.h"
#include "llvm/ExecutionEngine/RTDyldMemoryManager.h"
#include "llvm/ExecutionEngine/RuntimeDyld.h"
namespace llvm {
class MCJIT;
class Module;
class ObjectCache;
// This is a helper class that the MCJIT execution engine uses for linking
// functions across modules that it owns. It aggregates the memory manager
// that is passed in to the MCJIT constructor and defers most functionality
// to that object.
class LinkingSymbolResolver : public LegacyJITSymbolResolver {
LinkingSymbolResolver(MCJIT &Parent,
std::shared_ptr<LegacyJITSymbolResolver> Resolver)
: ParentEngine(Parent), ClientResolver(std::move(Resolver)) {}
JITSymbol findSymbol(const std::string &Name) override;
// MCJIT doesn't support logical dylibs.
JITSymbol findSymbolInLogicalDylib(const std::string &Name) override {
return nullptr;
MCJIT &ParentEngine;
std::shared_ptr<LegacyJITSymbolResolver> ClientResolver;
void anchor() override;
// About Module states: added->loaded->finalized.
// The purpose of the "added" state is having modules in standby. (added=known
// but not compiled). The idea is that you can add a module to provide function
// definitions but if nothing in that module is referenced by a module in which
// a function is executed (note the wording here because it's not exactly the
// ideal case) then the module never gets compiled. This is sort of lazy
// compilation.
// The purpose of the "loaded" state (loaded=compiled and required sections
// copied into local memory but not yet ready for execution) is to have an
// intermediate state wherein clients can remap the addresses of sections, using
// MCJIT::mapSectionAddress, (in preparation for later copying to a new location
// or an external process) before relocations and page permissions are applied.
// It might not be obvious at first glance, but the "remote-mcjit" case in the
// lli tool does this. In that case, the intermediate action is taken by the
// RemoteMemoryManager in response to the notifyObjectLoaded function being
// called.
class MCJIT : public ExecutionEngine {
MCJIT(std::unique_ptr<Module> M, std::unique_ptr<TargetMachine> tm,
std::shared_ptr<MCJITMemoryManager> MemMgr,
std::shared_ptr<LegacyJITSymbolResolver> Resolver);
typedef llvm::SmallPtrSet<Module *, 4> ModulePtrSet;
class OwningModuleContainer {
OwningModuleContainer() {
~OwningModuleContainer() {
ModulePtrSet::iterator begin_added() { return AddedModules.begin(); }
ModulePtrSet::iterator end_added() { return AddedModules.end(); }
iterator_range<ModulePtrSet::iterator> added() {
return make_range(begin_added(), end_added());
ModulePtrSet::iterator begin_loaded() { return LoadedModules.begin(); }
ModulePtrSet::iterator end_loaded() { return LoadedModules.end(); }
ModulePtrSet::iterator begin_finalized() { return FinalizedModules.begin(); }
ModulePtrSet::iterator end_finalized() { return FinalizedModules.end(); }
void addModule(std::unique_ptr<Module> M) {
bool removeModule(Module *M) {
return AddedModules.erase(M) || LoadedModules.erase(M) ||
bool hasModuleBeenAddedButNotLoaded(Module *M) {
return AddedModules.contains(M);
bool hasModuleBeenLoaded(Module *M) {
// If the module is in either the "loaded" or "finalized" sections it
// has been loaded.
return LoadedModules.contains(M) || FinalizedModules.contains(M);
bool hasModuleBeenFinalized(Module *M) {
return FinalizedModules.contains(M);
bool ownsModule(Module* M) {
return AddedModules.contains(M) || LoadedModules.contains(M) ||
void markModuleAsLoaded(Module *M) {
// This checks against logic errors in the MCJIT implementation.
// This function should never be called with either a Module that MCJIT
// does not own or a Module that has already been loaded and/or finalized.
assert(AddedModules.count(M) &&
"markModuleAsLoaded: Module not found in AddedModules");
// Remove the module from the "Added" set.
// Add the Module to the "Loaded" set.
void markModuleAsFinalized(Module *M) {
// This checks against logic errors in the MCJIT implementation.
// This function should never be called with either a Module that MCJIT
// does not own, a Module that has not been loaded or a Module that has
// already been finalized.
assert(LoadedModules.count(M) &&
"markModuleAsFinalized: Module not found in LoadedModules");
// Remove the module from the "Loaded" section of the list.
// Add the Module to the "Finalized" section of the list by inserting it
// before the 'end' iterator.
void markAllLoadedModulesAsFinalized() {
for (ModulePtrSet::iterator I = LoadedModules.begin(),
E = LoadedModules.end();
I != E; ++I) {
Module *M = *I;
ModulePtrSet AddedModules;
ModulePtrSet LoadedModules;
ModulePtrSet FinalizedModules;
void freeModulePtrSet(ModulePtrSet& MPS) {
// Go through the module set and delete everything.
for (ModulePtrSet::iterator I = MPS.begin(), E = MPS.end(); I != E; ++I) {
Module *M = *I;
delete M;
std::unique_ptr<TargetMachine> TM;
MCContext *Ctx;
std::shared_ptr<MCJITMemoryManager> MemMgr;
LinkingSymbolResolver Resolver;
RuntimeDyld Dyld;
std::vector<JITEventListener*> EventListeners;
OwningModuleContainer OwnedModules;
SmallVector<object::OwningBinary<object::Archive>, 2> Archives;
SmallVector<std::unique_ptr<MemoryBuffer>, 2> Buffers;
SmallVector<std::unique_ptr<object::ObjectFile>, 2> LoadedObjects;
// An optional ObjectCache to be notified of compiled objects and used to
// perform lookup of pre-compiled code to avoid re-compilation.
ObjectCache *ObjCache;
Function *FindFunctionNamedInModulePtrSet(StringRef FnName,
ModulePtrSet::iterator I,
ModulePtrSet::iterator E);
GlobalVariable *FindGlobalVariableNamedInModulePtrSet(StringRef Name,
bool AllowInternal,
ModulePtrSet::iterator I,
ModulePtrSet::iterator E);
void runStaticConstructorsDestructorsInModulePtrSet(bool isDtors,
ModulePtrSet::iterator I,
ModulePtrSet::iterator E);
~MCJIT() override;
/// @name ExecutionEngine interface implementation
/// @{
void addModule(std::unique_ptr<Module> M) override;
void addObjectFile(std::unique_ptr<object::ObjectFile> O) override;
void addObjectFile(object::OwningBinary<object::ObjectFile> O) override;
void addArchive(object::OwningBinary<object::Archive> O) override;
bool removeModule(Module *M) override;
/// FindFunctionNamed - Search all of the active modules to find the function that
/// defines FnName. This is very slow operation and shouldn't be used for
/// general code.
Function *FindFunctionNamed(StringRef FnName) override;
/// FindGlobalVariableNamed - Search all of the active modules to find the
/// global variable that defines Name. This is very slow operation and
/// shouldn't be used for general code.
GlobalVariable *FindGlobalVariableNamed(StringRef Name,
bool AllowInternal = false) override;
/// Sets the object manager that MCJIT should use to avoid compilation.
void setObjectCache(ObjectCache *manager) override;
void setProcessAllSections(bool ProcessAllSections) override {
void generateCodeForModule(Module *M) override;
/// finalizeObject - ensure the module is fully processed and is usable.
/// It is the user-level function for completing the process of making the
/// object usable for execution. It should be called after sections within an
/// object have been relocated using mapSectionAddress. When this method is
/// called the MCJIT execution engine will reapply relocations for a loaded
/// object.
/// Is it OK to finalize a set of modules, add modules and finalize again.
// FIXME: Do we really need both of these?
void finalizeObject() override;
virtual void finalizeModule(Module *);
void finalizeLoadedModules();
/// runStaticConstructorsDestructors - This method is used to execute all of
/// the static constructors or destructors for a program.
/// \param isDtors - Run the destructors instead of constructors.
void runStaticConstructorsDestructors(bool isDtors) override;
void *getPointerToFunction(Function *F) override;
GenericValue runFunction(Function *F,
ArrayRef<GenericValue> ArgValues) override;
/// getPointerToNamedFunction - This method returns the address of the
/// specified function by using the dlsym function call. As such it is only
/// useful for resolving library symbols, not code generated symbols.
/// If AbortOnFailure is false and no function with the given name is
/// found, this function silently returns a null pointer. Otherwise,
/// it prints a message to stderr and aborts.
void *getPointerToNamedFunction(StringRef Name,
bool AbortOnFailure = true) override;
/// mapSectionAddress - map a section to its target address space value.
/// Map the address of a JIT section as returned from the memory manager
/// to the address in the target process as the running code will see it.
/// This is the address which will be used for relocation resolution.
void mapSectionAddress(const void *LocalAddress,
uint64_t TargetAddress) override {
Dyld.mapSectionAddress(LocalAddress, TargetAddress);
void RegisterJITEventListener(JITEventListener *L) override;
void UnregisterJITEventListener(JITEventListener *L) override;
// If successful, these function will implicitly finalize all loaded objects.
// To get a function address within MCJIT without causing a finalize, use
// getSymbolAddress.
uint64_t getGlobalValueAddress(const std::string &Name) override;
uint64_t getFunctionAddress(const std::string &Name) override;
TargetMachine *getTargetMachine() override { return TM.get(); }
/// @}
/// @name (Private) Registration Interfaces
/// @{
static void Register() {
MCJITCtor = createJIT;
static ExecutionEngine *
createJIT(std::unique_ptr<Module> M, std::string *ErrorStr,
std::shared_ptr<MCJITMemoryManager> MemMgr,
std::shared_ptr<LegacyJITSymbolResolver> Resolver,
std::unique_ptr<TargetMachine> TM);
// @}
// Takes a mangled name and returns the corresponding JITSymbol (if a
// definition of that mangled name has been added to the JIT).
JITSymbol findSymbol(const std::string &Name, bool CheckFunctionsOnly);
// DEPRECATED - Please use findSymbol instead.
// This is not directly exposed via the ExecutionEngine API, but it is
// used by the LinkingMemoryManager.
// getSymbolAddress takes an unmangled name and returns the corresponding
// JITSymbol if a definition of the name has been added to the JIT.
uint64_t getSymbolAddress(const std::string &Name,
bool CheckFunctionsOnly);
/// emitObject -- Generate a JITed object in memory from the specified module
/// Currently, MCJIT only supports a single module and the module passed to
/// this function call is expected to be the contained module. The module
/// is passed as a parameter here to prepare for multiple module support in
/// the future.
std::unique_ptr<MemoryBuffer> emitObject(Module *M);
void notifyObjectLoaded(const object::ObjectFile &Obj,
const RuntimeDyld::LoadedObjectInfo &L);
void notifyFreeingObject(const object::ObjectFile &Obj);
JITSymbol findExistingSymbol(const std::string &Name);
Module *findModuleForSymbol(const std::string &Name, bool CheckFunctionsOnly);
} // end llvm namespace