llvm/llvm/lib/ExecutionEngine/MCJIT/MCJIT.h

//===-- MCJIT.h - Class definition for the MCJIT ----------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_LIB_EXECUTIONENGINE_MCJIT_MCJIT_H
#define LLVM_LIB_EXECUTIONENGINE_MCJIT_MCJIT_H

#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 { … };

// 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 { … };

} // end llvm namespace

#endif // LLVM_LIB_EXECUTIONENGINE_MCJIT_MCJIT_H