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//===- ExecutionEngine.h - Abstract Execution Engine Interface --*- 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
// This file defines the abstract interface that implements execution support
// for LLVM.
#include "llvm-c/ExecutionEngine.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ExecutionEngine/JITSymbol.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Module.h"
#include "llvm/Object/Binary.h"
#include "llvm/Support/CBindingWrapping.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Mutex.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include <algorithm>
#include <cstdint>
#include <functional>
#include <map>
#include <memory>
#include <optional>
#include <string>
#include <vector>
namespace llvm {
class Constant;
class Function;
struct GenericValue;
class GlobalValue;
class GlobalVariable;
class JITEventListener;
class MCJITMemoryManager;
class ObjectCache;
class RTDyldMemoryManager;
class Triple;
class Type;
namespace object {
class Archive;
class ObjectFile;
} // end namespace object
/// Helper class for helping synchronize access to the global address map
/// table. Access to this class should be serialized under a mutex.
class ExecutionEngineState {
using GlobalAddressMapTy = StringMap<uint64_t>;
/// GlobalAddressMap - A mapping between LLVM global symbol names values and
/// their actualized version...
GlobalAddressMapTy GlobalAddressMap;
/// GlobalAddressReverseMap - This is the reverse mapping of GlobalAddressMap,
/// used to convert raw addresses into the LLVM global value that is emitted
/// at the address. This map is not computed unless getGlobalValueAtAddress
/// is called at some point.
std::map<uint64_t, std::string> GlobalAddressReverseMap;
GlobalAddressMapTy &getGlobalAddressMap() {
return GlobalAddressMap;
std::map<uint64_t, std::string> &getGlobalAddressReverseMap() {
return GlobalAddressReverseMap;
/// Erase an entry from the mapping table.
/// \returns The address that \p ToUnmap was happed to.
uint64_t RemoveMapping(StringRef Name);
using FunctionCreator = std::function<void *(const std::string &)>;
/// Abstract interface for implementation execution of LLVM modules,
/// designed to support both interpreter and just-in-time (JIT) compiler
/// implementations.
class ExecutionEngine {
/// The state object holding the global address mapping, which must be
/// accessed synchronously.
// FIXME: There is no particular need the entire map needs to be
// synchronized. Wouldn't a reader-writer design be better here?
ExecutionEngineState EEState;
/// The target data for the platform for which execution is being performed.
/// Note: the DataLayout is LLVMContext specific because it has an
/// internal cache based on type pointers. It makes unsafe to reuse the
/// ExecutionEngine across context, we don't enforce this rule but undefined
/// behavior can occurs if the user tries to do it.
const DataLayout DL;
/// Whether lazy JIT compilation is enabled.
bool CompilingLazily;
/// Whether JIT compilation of external global variables is allowed.
bool GVCompilationDisabled;
/// Whether the JIT should perform lookups of external symbols (e.g.,
/// using dlsym).
bool SymbolSearchingDisabled;
/// Whether the JIT should verify IR modules during compilation.
bool VerifyModules;
friend class EngineBuilder; // To allow access to JITCtor and InterpCtor.
/// The list of Modules that we are JIT'ing from. We use a SmallVector to
/// optimize for the case where there is only one module.
SmallVector<std::unique_ptr<Module>, 1> Modules;
/// getMemoryforGV - Allocate memory for a global variable.
virtual char *getMemoryForGV(const GlobalVariable *GV);
static ExecutionEngine *(*MCJITCtor)(
std::unique_ptr<Module> M, std::string *ErrorStr,
std::shared_ptr<MCJITMemoryManager> MM,
std::shared_ptr<LegacyJITSymbolResolver> SR,
std::unique_ptr<TargetMachine> TM);
static ExecutionEngine *(*InterpCtor)(std::unique_ptr<Module> M,
std::string *ErrorStr);
/// LazyFunctionCreator - If an unknown function is needed, this function
/// pointer is invoked to create it. If this returns null, the JIT will
/// abort.
FunctionCreator LazyFunctionCreator;
/// getMangledName - Get mangled name.
std::string getMangledName(const GlobalValue *GV);
std::string ErrMsg;
/// lock - This lock protects the ExecutionEngine and MCJIT classes. It must
/// be held while changing the internal state of any of those classes.
sys::Mutex lock;
// ExecutionEngine Startup
virtual ~ExecutionEngine();
/// Add a Module to the list of modules that we can JIT from.
virtual void addModule(std::unique_ptr<Module> M) {
/// addObjectFile - Add an ObjectFile to the execution engine.
/// This method is only supported by MCJIT. MCJIT will immediately load the
/// object into memory and adds its symbols to the list used to resolve
/// external symbols while preparing other objects for execution.
/// Objects added using this function will not be made executable until
/// needed by another object.
/// MCJIT will take ownership of the ObjectFile.
virtual void addObjectFile(std::unique_ptr<object::ObjectFile> O);
virtual void addObjectFile(object::OwningBinary<object::ObjectFile> O);
/// addArchive - Add an Archive to the execution engine.
/// This method is only supported by MCJIT. MCJIT will use the archive to
/// resolve external symbols in objects it is loading. If a symbol is found
/// in the Archive the contained object file will be extracted (in memory)
/// and loaded for possible execution.
virtual void addArchive(object::OwningBinary<object::Archive> A);
const DataLayout &getDataLayout() const { return DL; }
/// removeModule - Removes a Module from the list of modules, but does not
/// free the module's memory. Returns true if M is found, in which case the
/// caller assumes responsibility for deleting the module.
// FIXME: This stealth ownership transfer is horrible. This will probably be
// fixed by deleting ExecutionEngine.
virtual bool removeModule(Module *M);
/// 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.
virtual Function *FindFunctionNamed(StringRef FnName);
/// 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.
virtual GlobalVariable *FindGlobalVariableNamed(StringRef Name, bool AllowInternal = false);
/// runFunction - Execute the specified function with the specified arguments,
/// and return the result.
/// For MCJIT execution engines, clients are encouraged to use the
/// "GetFunctionAddress" method (rather than runFunction) and cast the
/// returned uint64_t to the desired function pointer type. However, for
/// backwards compatibility MCJIT's implementation can execute 'main-like'
/// function (i.e. those returning void or int, and taking either no
/// arguments or (int, char*[])).
virtual GenericValue runFunction(Function *F,
ArrayRef<GenericValue> ArgValues) = 0;
/// 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.
/// This function is deprecated for the MCJIT execution engine.
virtual void *getPointerToNamedFunction(StringRef Name,
bool AbortOnFailure = true) = 0;
/// 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.
virtual void mapSectionAddress(const void *LocalAddress,
uint64_t TargetAddress) {
llvm_unreachable("Re-mapping of section addresses not supported with this "
/// generateCodeForModule - Run code generation for the specified module and
/// load it into memory.
/// When this function has completed, all code and data for the specified
/// module, and any module on which this module depends, will be generated
/// and loaded into memory, but relocations will not yet have been applied
/// and all memory will be readable and writable but not executable.
/// This function is primarily useful when generating code for an external
/// target, allowing the client an opportunity to remap section addresses
/// before relocations are applied. Clients that intend to execute code
/// locally can use the getFunctionAddress call, which will generate code
/// and apply final preparations all in one step.
/// This method has no effect for the interpeter.
virtual void generateCodeForModule(Module *M) {}
/// 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. This method has no effect for the interpeter.
/// Returns true on success, false on failure. Error messages can be retrieved
/// by calling getError();
virtual void finalizeObject() {}
/// Returns true if an error has been recorded.
bool hasError() const { return !ErrMsg.empty(); }
/// Clear the error message.
void clearErrorMessage() { ErrMsg.clear(); }
/// Returns the most recent error message.
const std::string &getErrorMessage() const { return ErrMsg; }
/// 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.
virtual void runStaticConstructorsDestructors(bool isDtors);
/// This method is used to execute all of the static constructors or
/// destructors for a particular module.
/// \param isDtors - Run the destructors instead of constructors.
void runStaticConstructorsDestructors(Module &module, bool isDtors);
/// runFunctionAsMain - This is a helper function which wraps runFunction to
/// handle the common task of starting up main with the specified argc, argv,
/// and envp parameters.
int runFunctionAsMain(Function *Fn, const std::vector<std::string> &argv,
const char * const * envp);
/// addGlobalMapping - Tell the execution engine that the specified global is
/// at the specified location. This is used internally as functions are JIT'd
/// and as global variables are laid out in memory. It can and should also be
/// used by clients of the EE that want to have an LLVM global overlay
/// existing data in memory. Values to be mapped should be named, and have
/// external or weak linkage. Mappings are automatically removed when their
/// GlobalValue is destroyed.
void addGlobalMapping(const GlobalValue *GV, void *Addr);
void addGlobalMapping(StringRef Name, uint64_t Addr);
/// clearAllGlobalMappings - Clear all global mappings and start over again,
/// for use in dynamic compilation scenarios to move globals.
void clearAllGlobalMappings();
/// clearGlobalMappingsFromModule - Clear all global mappings that came from a
/// particular module, because it has been removed from the JIT.
void clearGlobalMappingsFromModule(Module *M);
/// updateGlobalMapping - Replace an existing mapping for GV with a new
/// address. This updates both maps as required. If "Addr" is null, the
/// entry for the global is removed from the mappings. This returns the old
/// value of the pointer, or null if it was not in the map.
uint64_t updateGlobalMapping(const GlobalValue *GV, void *Addr);
uint64_t updateGlobalMapping(StringRef Name, uint64_t Addr);
/// getAddressToGlobalIfAvailable - This returns the address of the specified
/// global symbol.
uint64_t getAddressToGlobalIfAvailable(StringRef S);
/// getPointerToGlobalIfAvailable - This returns the address of the specified
/// global value if it is has already been codegen'd, otherwise it returns
/// null.
void *getPointerToGlobalIfAvailable(StringRef S);
void *getPointerToGlobalIfAvailable(const GlobalValue *GV);
/// getPointerToGlobal - This returns the address of the specified global
/// value. This may involve code generation if it's a function.
/// This function is deprecated for the MCJIT execution engine. Use
/// getGlobalValueAddress instead.
void *getPointerToGlobal(const GlobalValue *GV);
/// getPointerToFunction - The different EE's represent function bodies in
/// different ways. They should each implement this to say what a function
/// pointer should look like. When F is destroyed, the ExecutionEngine will
/// remove its global mapping and free any machine code. Be sure no threads
/// are running inside F when that happens.
/// This function is deprecated for the MCJIT execution engine. Use
/// getFunctionAddress instead.
virtual void *getPointerToFunction(Function *F) = 0;
/// getPointerToFunctionOrStub - If the specified function has been
/// code-gen'd, return a pointer to the function. If not, compile it, or use
/// a stub to implement lazy compilation if available. See
/// getPointerToFunction for the requirements on destroying F.
/// This function is deprecated for the MCJIT execution engine. Use
/// getFunctionAddress instead.
virtual void *getPointerToFunctionOrStub(Function *F) {
// Default implementation, just codegen the function.
return getPointerToFunction(F);
/// getGlobalValueAddress - Return the address of the specified global
/// value. This may involve code generation.
/// This function should not be called with the interpreter engine.
virtual uint64_t getGlobalValueAddress(const std::string &Name) {
// Default implementation for the interpreter. MCJIT will override this.
// JIT and interpreter clients should use getPointerToGlobal instead.
return 0;
/// getFunctionAddress - Return the address of the specified function.
/// This may involve code generation.
virtual uint64_t getFunctionAddress(const std::string &Name) {
// Default implementation for the interpreter. MCJIT will override this.
// Interpreter clients should use getPointerToFunction instead.
return 0;
/// getGlobalValueAtAddress - Return the LLVM global value object that starts
/// at the specified address.
const GlobalValue *getGlobalValueAtAddress(void *Addr);
/// StoreValueToMemory - Stores the data in Val of type Ty at address Ptr.
/// Ptr is the address of the memory at which to store Val, cast to
/// GenericValue *. It is not a pointer to a GenericValue containing the
/// address at which to store Val.
void StoreValueToMemory(const GenericValue &Val, GenericValue *Ptr,
Type *Ty);
void InitializeMemory(const Constant *Init, void *Addr);
/// getOrEmitGlobalVariable - Return the address of the specified global
/// variable, possibly emitting it to memory if needed. This is used by the
/// Emitter.
/// This function is deprecated for the MCJIT execution engine. Use
/// getGlobalValueAddress instead.
virtual void *getOrEmitGlobalVariable(const GlobalVariable *GV) {
return getPointerToGlobal((const GlobalValue *)GV);
/// Registers a listener to be called back on various events within
/// the JIT. See JITEventListener.h for more details. Does not
/// take ownership of the argument. The argument may be NULL, in
/// which case these functions do nothing.
virtual void RegisterJITEventListener(JITEventListener *) {}
virtual void UnregisterJITEventListener(JITEventListener *) {}
/// Sets the pre-compiled object cache. The ownership of the ObjectCache is
/// not changed. Supported by MCJIT but not the interpreter.
virtual void setObjectCache(ObjectCache *) {
llvm_unreachable("No support for an object cache");
/// setProcessAllSections (MCJIT Only): By default, only sections that are
/// "required for execution" are passed to the RTDyldMemoryManager, and other
/// sections are discarded. Passing 'true' to this method will cause
/// RuntimeDyld to pass all sections to its RTDyldMemoryManager regardless
/// of whether they are "required to execute" in the usual sense.
/// Rationale: Some MCJIT clients want to be able to inspect metadata
/// sections (e.g. Dwarf, Stack-maps) to enable functionality or analyze
/// performance. Passing these sections to the memory manager allows the
/// client to make policy about the relevant sections, rather than having
/// MCJIT do it.
virtual void setProcessAllSections(bool ProcessAllSections) {
llvm_unreachable("No support for ProcessAllSections option");
/// Return the target machine (if available).
virtual TargetMachine *getTargetMachine() { return nullptr; }
/// DisableLazyCompilation - When lazy compilation is off (the default), the
/// JIT will eagerly compile every function reachable from the argument to
/// getPointerToFunction. If lazy compilation is turned on, the JIT will only
/// compile the one function and emit stubs to compile the rest when they're
/// first called. If lazy compilation is turned off again while some lazy
/// stubs are still around, and one of those stubs is called, the program will
/// abort.
/// In order to safely compile lazily in a threaded program, the user must
/// ensure that 1) only one thread at a time can call any particular lazy
/// stub, and 2) any thread modifying LLVM IR must hold the JIT's lock
/// (ExecutionEngine::lock) or otherwise ensure that no other thread calls a
/// lazy stub. See for details.
void DisableLazyCompilation(bool Disabled = true) {
CompilingLazily = !Disabled;
bool isCompilingLazily() const {
return CompilingLazily;
/// DisableGVCompilation - If called, the JIT will abort if it's asked to
/// allocate space and populate a GlobalVariable that is not internal to
/// the module.
void DisableGVCompilation(bool Disabled = true) {
GVCompilationDisabled = Disabled;
bool isGVCompilationDisabled() const {
return GVCompilationDisabled;
/// DisableSymbolSearching - If called, the JIT will not try to lookup unknown
/// symbols with dlsym. A client can still use InstallLazyFunctionCreator to
/// resolve symbols in a custom way.
void DisableSymbolSearching(bool Disabled = true) {
SymbolSearchingDisabled = Disabled;
bool isSymbolSearchingDisabled() const {
return SymbolSearchingDisabled;
/// Enable/Disable IR module verification.
/// Note: Module verification is enabled by default in Debug builds, and
/// disabled by default in Release. Use this method to override the default.
void setVerifyModules(bool Verify) {
VerifyModules = Verify;
bool getVerifyModules() const {
return VerifyModules;
/// InstallLazyFunctionCreator - If an unknown function is needed, the
/// specified function pointer is invoked to create it. If it returns null,
/// the JIT will abort.
void InstallLazyFunctionCreator(FunctionCreator C) {
LazyFunctionCreator = std::move(C);
ExecutionEngine(DataLayout DL) : DL(std::move(DL)) {}
explicit ExecutionEngine(DataLayout DL, std::unique_ptr<Module> M);
explicit ExecutionEngine(std::unique_ptr<Module> M);
void emitGlobals();
void emitGlobalVariable(const GlobalVariable *GV);
GenericValue getConstantValue(const Constant *C);
void LoadValueFromMemory(GenericValue &Result, GenericValue *Ptr,
Type *Ty);
void Init(std::unique_ptr<Module> M);
namespace EngineKind {
// These are actually bitmasks that get or-ed together.
enum Kind {
JIT = 0x1,
Interpreter = 0x2
const static Kind Either = (Kind)(JIT | Interpreter);
} // end namespace EngineKind
/// Builder class for ExecutionEngines. Use this by stack-allocating a builder,
/// chaining the various set* methods, and terminating it with a .create()
/// call.
class EngineBuilder {
std::unique_ptr<Module> M;
EngineKind::Kind WhichEngine;
std::string *ErrorStr;
CodeGenOpt::Level OptLevel;
std::shared_ptr<MCJITMemoryManager> MemMgr;
std::shared_ptr<LegacyJITSymbolResolver> Resolver;
TargetOptions Options;
std::optional<Reloc::Model> RelocModel;
std::optional<CodeModel::Model> CMModel;
std::string MArch;
std::string MCPU;
SmallVector<std::string, 4> MAttrs;
bool VerifyModules;
bool EmulatedTLS = true;
/// Default constructor for EngineBuilder.
/// Constructor for EngineBuilder.
EngineBuilder(std::unique_ptr<Module> M);
// Out-of-line since we don't have the def'n of RTDyldMemoryManager here.
/// setEngineKind - Controls whether the user wants the interpreter, the JIT,
/// or whichever engine works. This option defaults to EngineKind::Either.
EngineBuilder &setEngineKind(EngineKind::Kind w) {
WhichEngine = w;
return *this;
/// setMCJITMemoryManager - Sets the MCJIT memory manager to use. This allows
/// clients to customize their memory allocation policies for the MCJIT. This
/// is only appropriate for the MCJIT; setting this and configuring the builder
/// to create anything other than MCJIT will cause a runtime error. If create()
/// is called and is successful, the created engine takes ownership of the
/// memory manager. This option defaults to NULL.
EngineBuilder &setMCJITMemoryManager(std::unique_ptr<RTDyldMemoryManager> mcjmm);
setMemoryManager(std::unique_ptr<MCJITMemoryManager> MM);
EngineBuilder &setSymbolResolver(std::unique_ptr<LegacyJITSymbolResolver> SR);
/// setErrorStr - Set the error string to write to on error. This option
/// defaults to NULL.
EngineBuilder &setErrorStr(std::string *e) {
ErrorStr = e;
return *this;
/// setOptLevel - Set the optimization level for the JIT. This option
/// defaults to CodeGenOpt::Default.
EngineBuilder &setOptLevel(CodeGenOpt::Level l) {
OptLevel = l;
return *this;
/// setTargetOptions - Set the target options that the ExecutionEngine
/// target is using. Defaults to TargetOptions().
EngineBuilder &setTargetOptions(const TargetOptions &Opts) {
Options = Opts;
return *this;
/// setRelocationModel - Set the relocation model that the ExecutionEngine
/// target is using. Defaults to target specific default "Reloc::Default".
EngineBuilder &setRelocationModel(Reloc::Model RM) {
RelocModel = RM;
return *this;
/// setCodeModel - Set the CodeModel that the ExecutionEngine target
/// data is using. Defaults to target specific default
/// "CodeModel::JITDefault".
EngineBuilder &setCodeModel(CodeModel::Model M) {
CMModel = M;
return *this;
/// setMArch - Override the architecture set by the Module's triple.
EngineBuilder &setMArch(StringRef march) {
MArch.assign(march.begin(), march.end());
return *this;
/// setMCPU - Target a specific cpu type.
EngineBuilder &setMCPU(StringRef mcpu) {
MCPU.assign(mcpu.begin(), mcpu.end());
return *this;
/// setVerifyModules - Set whether the JIT implementation should verify
/// IR modules during compilation.
EngineBuilder &setVerifyModules(bool Verify) {
VerifyModules = Verify;
return *this;
/// setMAttrs - Set cpu-specific attributes.
template<typename StringSequence>
EngineBuilder &setMAttrs(const StringSequence &mattrs) {
MAttrs.append(mattrs.begin(), mattrs.end());
return *this;
void setEmulatedTLS(bool EmulatedTLS) {
this->EmulatedTLS = EmulatedTLS;
TargetMachine *selectTarget();
/// selectTarget - Pick a target either via -march or by guessing the native
/// arch. Add any CPU features specified via -mcpu or -mattr.
TargetMachine *selectTarget(const Triple &TargetTriple,
StringRef MArch,
StringRef MCPU,
const SmallVectorImpl<std::string>& MAttrs);
ExecutionEngine *create() {
return create(selectTarget());
ExecutionEngine *create(TargetMachine *TM);
// Create wrappers for C Binding types (see CBindingWrapping.h).
} // end namespace llvm