3 files changed, 460 insertions, 79 deletions

diff --git a/lib/ExecutionEngine/MCJIT/MCJIT.cpp b/lib/ExecutionEngine/MCJIT/MCJIT.cpp
index 09dd924..195c458 100644
--- a/lib/ExecutionEngine/MCJIT/MCJIT.cpp
+++ b/lib/ExecutionEngine/MCJIT/MCJIT.cpp
@@ -14,10 +14,12 @@
 #include "llvm/ExecutionEngine/MCJIT.h"
 #include "llvm/ExecutionEngine/ObjectBuffer.h"
 #include "llvm/ExecutionEngine/ObjectImage.h"
+#include "llvm/PassManager.h"
 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
+#include "llvm/IR/Module.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/Support/DynamicLibrary.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -53,37 +55,63 @@ ExecutionEngine *MCJIT::createJIT(Module *M,
 
 MCJIT::MCJIT(Module *m, TargetMachine *tm, RTDyldMemoryManager *MM,
              bool AllocateGVsWithCode)
-  : ExecutionEngine(m), TM(tm), Ctx(0), MemMgr(MM), Dyld(MM),
-    IsLoaded(false), M(m), ObjCache(0) {
+  : ExecutionEngine(m), TM(tm), Ctx(0), MemMgr(this, MM), Dyld(&MemMgr),
+    ObjCache(0) {
 
+  OwnedModules.addModule(m);
   setDataLayout(TM->getDataLayout());
 }
 
 MCJIT::~MCJIT() {
-  if (LoadedObject)
-    NotifyFreeingObject(*LoadedObject.get());
-  delete MemMgr;
+  MutexGuard locked(lock);
+  // 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.
+  //
+  Modules.clear();
+  Dyld.deregisterEHFrames();
+
+  LoadedObjectMap::iterator it, end = LoadedObjects.end();
+  for (it = LoadedObjects.begin(); it != end; ++it) {
+    ObjectImage *Obj = it->second;
+    if (Obj) {
+      NotifyFreeingObject(*Obj);
+      delete Obj;
+    }
+  }
+  LoadedObjects.clear();
   delete TM;
 }
 
+void MCJIT::addModule(Module *M) {
+  MutexGuard locked(lock);
+  OwnedModules.addModule(M);
+}
+
+bool MCJIT::removeModule(Module *M) {
+  MutexGuard locked(lock);
+  return OwnedModules.removeModule(M);
+}
+
+
+
 void MCJIT::setObjectCache(ObjectCache* NewCache) {
+  MutexGuard locked(lock);
   ObjCache = NewCache;
 }
 
-ObjectBufferStream* MCJIT::emitObject(Module *m) {
-  /// 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.
-  assert(M == m);
-
-  // Get a thread lock to make sure we aren't trying to compile multiple times
+ObjectBufferStream* MCJIT::emitObject(Module *M) {
   MutexGuard locked(lock);
 
-  // FIXME: Track compilation state on a per-module basis when multiple modules
-  //        are supported.
-  // Re-compilation is not supported
-  assert(!IsLoaded);
+  // 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.
 
   PassManager PM;
 
@@ -99,7 +127,7 @@ ObjectBufferStream* MCJIT::emitObject(Module *m) {
   }
 
   // Initialize passes.
-  PM.run(*m);
+  PM.run(*M);
   // Flush the output buffer to get the generated code into memory
   CompiledObject->flush();
 
@@ -109,21 +137,22 @@ ObjectBufferStream* MCJIT::emitObject(Module *m) {
     // 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.
     OwningPtr<MemoryBuffer> MB(CompiledObject->getMemBuffer());
-    ObjCache->notifyObjectCompiled(m, MB.get());
+    ObjCache->notifyObjectCompiled(M, MB.get());
   }
 
   return CompiledObject.take();
 }
 
-void MCJIT::loadObject(Module *M) {
-
+void MCJIT::generateCodeForModule(Module *M) {
   // Get a thread lock to make sure we aren't trying to load multiple times
   MutexGuard locked(lock);
 
-  // FIXME: Track compilation state on a per-module basis when multiple modules
-  //        are supported.
+  // 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 (IsLoaded)
+  if (OwnedModules.hasModuleBeenLoaded(M))
     return;
 
   OwningPtr<ObjectBuffer> ObjectToLoad;
@@ -141,59 +170,137 @@ void MCJIT::loadObject(Module *M) {
   }
 
   // Load the object into the dynamic linker.
-  // handing off ownership of the buffer
-  LoadedObject.reset(Dyld.loadObject(ObjectToLoad.take()));
+  // MCJIT now owns the ObjectImage pointer (via its LoadedObjects map).
+  ObjectImage *LoadedObject = Dyld.loadObject(ObjectToLoad.take());
+  LoadedObjects[M] = LoadedObject;
   if (!LoadedObject)
     report_fatal_error(Dyld.getErrorString());
 
-  // Resolve any relocations.
-  Dyld.resolveRelocations();
-
   // FIXME: Make this optional, maybe even move it to a JIT event listener
   LoadedObject->registerWithDebugger();
 
   NotifyObjectEmitted(*LoadedObject);
 
-  // FIXME: Add support for per-module compilation state
-  IsLoaded = true;
+  OwnedModules.markModuleAsLoaded(M);
 }
 
-// FIXME: Add a parameter to identify which object is being finalized when
-// MCJIT supports multiple modules.
-// FIXME: Provide a way to separate code emission, relocations and page 
-// protection in the interface.
+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() {
-  // If the module hasn't been compiled, just do that.
-  if (!IsLoaded) {
-    // If the call to Dyld.resolveRelocations() is removed from loadObject()
-    // we'll need to do that here.
-    loadObject(M);
-  } else {
-    // Resolve any relocations.
-    Dyld.resolveRelocations();
+  MutexGuard locked(lock);
+
+  for (ModulePtrSet::iterator I = OwnedModules.begin_added(),
+                              E = OwnedModules.end_added();
+       I != E; ++I) {
+    Module *M = *I;
+    generateCodeForModule(M);
   }
 
-  StringRef EHData = Dyld.getEHFrameSection();
-  if (!EHData.empty())
-    MemMgr->registerEHFrames(EHData);
+  finalizeLoadedModules();
+}
 
-  // Set page permissions.
-  MemMgr->finalizeMemory();
+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();
 }
 
 void *MCJIT::getPointerToBasicBlock(BasicBlock *BB) {
   report_fatal_error("not yet implemented");
 }
 
-void *MCJIT::getPointerToFunction(Function *F) {
-  // FIXME: This should really return a uint64_t since it's a pointer in the
-  // target address space, not our local address space. That's part of the
-  // ExecutionEngine interface, though. Fix that when the old JIT finally
-  // dies.
+uint64_t MCJIT::getExistingSymbolAddress(const std::string &Name) {
+  // Check with the RuntimeDyld to see if we already have this symbol.
+  if (Name[0] == '\1')
+    return Dyld.getSymbolLoadAddress(Name.substr(1));
+  return Dyld.getSymbolLoadAddress((TM->getMCAsmInfo()->getGlobalPrefix()
+                                       + Name));
+}
+
+Module *MCJIT::findModuleForSymbol(const std::string &Name,
+                                   bool CheckFunctionsOnly) {
+  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(Name);
+    if (F && !F->isDeclaration())
+      return M;
+    if (!CheckFunctionsOnly) {
+      GlobalVariable *G = M->getGlobalVariable(Name);
+      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 NULL;
+}
+
+uint64_t MCJIT::getSymbolAddress(const std::string &Name,
+                                 bool CheckFunctionsOnly)
+{
+  MutexGuard locked(lock);
+
+  // First, check to see if we already have this symbol.
+  uint64_t Addr = getExistingSymbolAddress(Name);
+  if (Addr)
+    return Addr;
+
+  // If it hasn't already been generated, see if it's in one of our modules.
+  Module *M = findModuleForSymbol(Name, CheckFunctionsOnly);
+  if (!M)
+    return 0;
+
+  generateCodeForModule(M);
+
+  // Check the RuntimeDyld table again, it should be there now.
+  return getExistingSymbolAddress(Name);
+}
 
-  // FIXME: Add support for per-module compilation state
-  if (!IsLoaded)
-    loadObject(M);
+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);
 
   if (F->isDeclaration() || F->hasAvailableExternallyLinkage()) {
     bool AbortOnFailure = !F->hasExternalWeakLinkage();
@@ -202,6 +309,16 @@ void *MCJIT::getPointerToFunction(Function *F) {
     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.
+    return NULL;
+
   // FIXME: Should the Dyld be retaining module information? Probably not.
   // FIXME: Should we be using the mangler for this? Probably.
   //
@@ -222,6 +339,45 @@ void MCJIT::freeMachineCodeForFunction(Function *F) {
   report_fatal_error("not yet implemented");
 }
 
+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(const char *FnName,
+                                                 ModulePtrSet::iterator I,
+                                                 ModulePtrSet::iterator E) {
+  for (; I != E; ++I) {
+    if (Function *F = (*I)->getFunction(FnName))
+      return F;
+  }
+  return 0;
+}
+
+Function *MCJIT::FindFunctionNamed(const char *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;
+}
+
 GenericValue MCJIT::runFunction(Function *F,
                                 const std::vector<GenericValue> &ArgValues) {
   assert(F && "Function *F was null at entry to run()");
@@ -324,12 +480,8 @@ GenericValue MCJIT::runFunction(Function *F,
 
 void *MCJIT::getPointerToNamedFunction(const std::string &Name,
                                        bool AbortOnFailure) {
-  // FIXME: Add support for per-module compilation state
-  if (!IsLoaded)
-    loadObject(M);
-
-  if (!isSymbolSearchingDisabled() && MemMgr) {
-    void *ptr = MemMgr->getPointerToNamedFunction(Name, false);
+  if (!isSymbolSearchingDisabled()) {
+    void *ptr = MemMgr.getPointerToNamedFunction(Name, false);
     if (ptr)
       return ptr;
   }
@@ -365,6 +517,7 @@ void MCJIT::UnregisterJITEventListener(JITEventListener *L) {
 }
 void MCJIT::NotifyObjectEmitted(const ObjectImage& Obj) {
   MutexGuard locked(lock);
+  MemMgr.notifyObjectLoaded(this, &Obj);
   for (unsigned I = 0, S = EventListeners.size(); I < S; ++I) {
     EventListeners[I]->NotifyObjectEmitted(Obj);
   }
@@ -375,3 +528,14 @@ void MCJIT::NotifyFreeingObject(const ObjectImage& Obj) {
     EventListeners[I]->NotifyFreeingObject(Obj);
   }
 }
+
+uint64_t LinkingMemoryManager::getSymbolAddress(const std::string &Name) {
+  uint64_t Result = ParentEngine->getSymbolAddress(Name, false);
+  // If the symbols wasn't found and it begins with an underscore, try again
+  // without the underscore.
+  if (!Result && Name[0] == '_')
+    Result = ParentEngine->getSymbolAddress(Name.substr(1), false);
+  if (Result)
+    return Result;
+  return ClientMM->getSymbolAddress(Name);
+}
diff --git a/lib/ExecutionEngine/MCJIT/MCJIT.h b/lib/ExecutionEngine/MCJIT/MCJIT.h
index a899d4f..86b478b 100644
--- a/lib/ExecutionEngine/MCJIT/MCJIT.h
+++ b/lib/ExecutionEngine/MCJIT/MCJIT.h
@@ -10,48 +10,235 @@
 #ifndef LLVM_LIB_EXECUTIONENGINE_MCJIT_H
 #define LLVM_LIB_EXECUTIONENGINE_MCJIT_H
 
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ExecutionEngine/ExecutionEngine.h"
 #include "llvm/ExecutionEngine/ObjectCache.h"
+#include "llvm/ExecutionEngine/ObjectImage.h"
 #include "llvm/ExecutionEngine/RuntimeDyld.h"
-#include "llvm/PassManager.h"
+#include "llvm/IR/Module.h"
 
 namespace llvm {
+class MCJIT;
 
-class ObjectImage;
+// 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 LinkingMemoryManager : public RTDyldMemoryManager {
+public:
+  LinkingMemoryManager(MCJIT *Parent, RTDyldMemoryManager *MM)
+    : ParentEngine(Parent), ClientMM(MM) {}
+
+  virtual uint64_t getSymbolAddress(const std::string &Name);
+
+  // Functions deferred to client memory manager
+  virtual uint8_t *allocateCodeSection(uintptr_t Size, unsigned Alignment,
+                                       unsigned SectionID, StringRef SectionName) {
+    return ClientMM->allocateCodeSection(Size, Alignment, SectionID, SectionName);
+  }
+
+  virtual uint8_t *allocateDataSection(uintptr_t Size, unsigned Alignment,
+                                       unsigned SectionID, StringRef SectionName,
+                                       bool IsReadOnly) {
+    return ClientMM->allocateDataSection(Size, Alignment,
+                                         SectionID, SectionName, IsReadOnly);
+  }
+
+  virtual void notifyObjectLoaded(ExecutionEngine *EE,
+                                  const ObjectImage *Obj) {
+    ClientMM->notifyObjectLoaded(EE, Obj);
+  }
+
+  virtual void registerEHFrames(uint8_t *Addr, uint64_t LoadAddr, size_t Size) {
+    ClientMM->registerEHFrames(Addr, LoadAddr, Size);
+  }
+
+  virtual void deregisterEHFrames(uint8_t *Addr,
+                                  uint64_t LoadAddr,
+                                  size_t Size) {
+    ClientMM->deregisterEHFrames(Addr, LoadAddr, Size);
+  }
+
+  virtual bool finalizeMemory(std::string *ErrMsg = 0) {
+    return ClientMM->finalizeMemory(ErrMsg);
+  }
 
-// FIXME: This makes all kinds of horrible assumptions for the time being,
-// like only having one module, not needing to worry about multi-threading,
-// blah blah. Purely in get-it-up-and-limping mode for now.
+private:
+  MCJIT *ParentEngine;
+  OwningPtr<RTDyldMemoryManager> ClientMM;
+};
+
+// 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(Module *M, TargetMachine *tm, RTDyldMemoryManager *MemMgr,
         bool AllocateGVsWithCode);
 
+  typedef llvm::SmallPtrSet<Module *, 4> ModulePtrSet;
+
+  class OwningModuleContainer {
+  public:
+    OwningModuleContainer() {
+    }
+    ~OwningModuleContainer() {
+      freeModulePtrSet(AddedModules);
+      freeModulePtrSet(LoadedModules);
+      freeModulePtrSet(FinalizedModules);
+    }
+
+    ModulePtrSet::iterator begin_added() { return AddedModules.begin(); }
+    ModulePtrSet::iterator end_added() { return AddedModules.end(); }
+
+    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(Module *M) {
+      AddedModules.insert(M);
+    }
+
+    bool removeModule(Module *M) {
+      return AddedModules.erase(M) || LoadedModules.erase(M) ||
+             FinalizedModules.erase(M);
+    }
+
+    bool hasModuleBeenAddedButNotLoaded(Module *M) {
+      return AddedModules.count(M) != 0;
+    }
+
+    bool hasModuleBeenLoaded(Module *M) {
+      // If the module is in either the "loaded" or "finalized" sections it
+      // has been loaded.
+      return (LoadedModules.count(M) != 0 ) || (FinalizedModules.count(M) != 0);
+    }
+
+    bool hasModuleBeenFinalized(Module *M) {
+      return FinalizedModules.count(M) != 0;
+    }
+
+    bool ownsModule(Module* M) {
+      return (AddedModules.count(M) != 0) || (LoadedModules.count(M) != 0) ||
+             (FinalizedModules.count(M) != 0);
+    }
+
+    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.
+      AddedModules.erase(M);
+
+      // Add the Module to the "Loaded" set.
+      LoadedModules.insert(M);
+    }
+
+    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.
+      LoadedModules.erase(M);
+
+      // Add the Module to the "Finalized" section of the list by inserting it
+      // before the 'end' iterator.
+      FinalizedModules.insert(M);
+    }
+
+    void markAllLoadedModulesAsFinalized() {
+      for (ModulePtrSet::iterator I = LoadedModules.begin(),
+                                  E = LoadedModules.end();
+           I != E; ++I) {
+        Module *M = *I;
+        FinalizedModules.insert(M);
+      }
+      LoadedModules.clear();
+    }
+
+  private:
+    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;
+      }
+      MPS.clear();
+    }
+  };
+
   TargetMachine *TM;
   MCContext *Ctx;
-  RTDyldMemoryManager *MemMgr;
+  LinkingMemoryManager MemMgr;
   RuntimeDyld Dyld;
   SmallVector<JITEventListener*, 2> EventListeners;
 
-  // FIXME: Add support for multiple modules
-  bool IsLoaded;
-  Module *M;
-  OwningPtr<ObjectImage> LoadedObject;
+  OwningModuleContainer OwnedModules;
+
+  typedef DenseMap<Module *, ObjectImage *> LoadedObjectMap;
+  LoadedObjectMap  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(const char *FnName,
+                                            ModulePtrSet::iterator I,
+                                            ModulePtrSet::iterator E);
+
+  void runStaticConstructorsDestructorsInModulePtrSet(bool isDtors,
+                                                      ModulePtrSet::iterator I,
+                                                      ModulePtrSet::iterator E);
+
 public:
   ~MCJIT();
 
   /// @name ExecutionEngine interface implementation
   /// @{
+  virtual void addModule(Module *M);
+  virtual bool removeModule(Module *M);
+
+  /// FindFunctionNamed - Search all of the active modules to find the one that
+  /// defines FnName.  This is very slow operation and shouldn't be used for
+  /// general code.
+  virtual Function *FindFunctionNamed(const char *FnName);
 
   /// Sets the object manager that MCJIT should use to avoid compilation.
   virtual void setObjectCache(ObjectCache *manager);
 
+  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
@@ -59,7 +246,17 @@ public:
   /// 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?
   virtual void finalizeObject();
+  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);
 
   virtual void *getPointerToBasicBlock(BasicBlock *BB);
 
@@ -91,10 +288,15 @@ public:
                                  uint64_t TargetAddress) {
     Dyld.mapSectionAddress(LocalAddress, TargetAddress);
   }
-
   virtual void RegisterJITEventListener(JITEventListener *L);
   virtual void UnregisterJITEventListener(JITEventListener *L);
 
+  // If successful, these function will implicitly finalize all loaded objects.
+  // To get a function address within MCJIT without causing a finalize, use
+  // getSymbolAddress.
+  virtual uint64_t getGlobalValueAddress(const std::string &Name);
+  virtual uint64_t getFunctionAddress(const std::string &Name);
+
   /// @}
   /// @name (Private) Registration Interfaces
   /// @{
@@ -111,6 +313,11 @@ public:
 
   // @}
 
+  // This is not directly exposed via the ExecutionEngine API, but it is
+  // used by the LinkingMemoryManager.
+  uint64_t getSymbolAddress(const std::string &Name,
+                          bool CheckFunctionsOnly);
+
 protected:
   /// emitObject -- Generate a JITed object in memory from the specified module
   /// Currently, MCJIT only supports a single module and the module passed to
@@ -119,10 +326,12 @@ protected:
   /// the future.
   ObjectBufferStream* emitObject(Module *M);
 
-  void loadObject(Module *M);
-
   void NotifyObjectEmitted(const ObjectImage& Obj);
   void NotifyFreeingObject(const ObjectImage& Obj);
+
+  uint64_t getExistingSymbolAddress(const std::string &Name);
+  Module *findModuleForSymbol(const std::string &Name,
+                              bool CheckFunctionsOnly);
 };
 
 } // End llvm namespace
diff --git a/lib/ExecutionEngine/MCJIT/SectionMemoryManager.cpp b/lib/ExecutionEngine/MCJIT/SectionMemoryManager.cpp
index 650832e..cf90e77 100644
--- a/lib/ExecutionEngine/MCJIT/SectionMemoryManager.cpp
+++ b/lib/ExecutionEngine/MCJIT/SectionMemoryManager.cpp
@@ -19,9 +19,10 @@
 namespace llvm {
 
 uint8_t *SectionMemoryManager::allocateDataSection(uintptr_t Size,
-                                                    unsigned Alignment,
-                                                    unsigned SectionID,
-                                                    bool IsReadOnly) {
+                                                   unsigned Alignment,
+                                                   unsigned SectionID,
+                                                   StringRef SectionName,
+                                                   bool IsReadOnly) {
   if (IsReadOnly)
     return allocateSection(RODataMem, Size, Alignment);
   return allocateSection(RWDataMem, Size, Alignment);
@@ -29,7 +30,8 @@ uint8_t *SectionMemoryManager::allocateDataSection(uintptr_t Size,
 
 uint8_t *SectionMemoryManager::allocateCodeSection(uintptr_t Size,
                                                    unsigned Alignment,
-                                                   unsigned SectionID) {
+                                                   unsigned SectionID,
+                                                   StringRef SectionName) {
   return allocateSection(CodeMem, Size, Alignment);
 }
 
@@ -105,6 +107,9 @@ bool SectionMemoryManager::finalizeMemory(std::string *ErrMsg)
   // FIXME: Should in-progress permissions be reverted if an error occurs?
   error_code ec;
 
+  // Don't allow free memory blocks to be used after setting protection flags.
+  CodeMem.FreeMem.clear();
+
   // Make code memory executable.
   ec = applyMemoryGroupPermissions(CodeMem,
                                    sys::Memory::MF_READ | sys::Memory::MF_EXEC);
@@ -115,6 +120,9 @@ bool SectionMemoryManager::finalizeMemory(std::string *ErrMsg)
     return true;
   }
 
+  // Don't allow free memory blocks to be used after setting protection flags.
+  RODataMem.FreeMem.clear();
+
   // Make read-only data memory read-only.
   ec = applyMemoryGroupPermissions(RODataMem,
                                    sys::Memory::MF_READ | sys::Memory::MF_EXEC);