[ORC] Switch the object layer API from addObjectSet to addObject (singular), and

move the ObjectCache from the IRCompileLayer to SimpleCompiler.

This is the first in a series of patches aimed at cleaning up and improving the
robustness and performance of the ORC APIs.

llvm-svn: 306058

5 files changed, 164 insertions, 187 deletions

diff --git a/llvm/include/llvm/ExecutionEngine/Orc/CompileUtils.h b/llvm/include/llvm/ExecutionEngine/Orc/CompileUtils.h
index 14b14943c82..b9f7d6accc3 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/CompileUtils.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/CompileUtils.h
@@ -15,6 +15,7 @@
 #define LLVM_EXECUTIONENGINE_ORC_COMPILEUTILS_H
 
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ExecutionEngine/ObjectCache.h"
 #include "llvm/ExecutionEngine/ObjectMemoryBuffer.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/Object/Binary.h"
@@ -38,11 +39,22 @@ namespace orc {
 ///        ObjectFile.
 class SimpleCompiler {
 public:
+
+  using CompileResult = object::OwningBinary<object::ObjectFile>;
+
   /// @brief Construct a simple compile functor with the given target.
-  SimpleCompiler(TargetMachine &TM) : TM(TM) {}
+  SimpleCompiler(TargetMachine &TM, ObjectCache *ObjCache = nullptr)
+    : TM(TM), ObjCache(ObjCache) {}
+
+  /// @brief Set an ObjectCache to query before compiling.
+  void setObjectCache(ObjectCache *NewCache) { ObjCache = NewCache; }
 
   /// @brief Compile a Module to an ObjectFile.
-  object::OwningBinary<object::ObjectFile> operator()(Module &M) const {
+  CompileResult operator()(Module &M) {
+    CompileResult CachedObject = tryToLoadFromObjectCache(M);
+    if (CachedObject.getBinary())
+      return CachedObject;
+
     SmallVector<char, 0> ObjBufferSV;
     raw_svector_ostream ObjStream(ObjBufferSV);
 
@@ -55,16 +67,43 @@ public:
         new ObjectMemoryBuffer(std::move(ObjBufferSV)));
     Expected<std::unique_ptr<object::ObjectFile>> Obj =
         object::ObjectFile::createObjectFile(ObjBuffer->getMemBufferRef());
-    using OwningObj = object::OwningBinary<object::ObjectFile>;
-    if (Obj)
-      return OwningObj(std::move(*Obj), std::move(ObjBuffer));
+    if (Obj) {
+      notifyObjectCompiled(M, *ObjBuffer);
+      return CompileResult(std::move(*Obj), std::move(ObjBuffer));
+    }
     // TODO: Actually report errors helpfully.
     consumeError(Obj.takeError());
-    return OwningObj(nullptr, nullptr);
+    return CompileResult(nullptr, nullptr);
   }
 
 private:
+
+  CompileResult tryToLoadFromObjectCache(const Module &M) {
+    if (!ObjCache)
+      return CompileResult();
+
+    std::unique_ptr<MemoryBuffer> ObjBuffer = ObjCache->getObject(&M);
+    if (!ObjBuffer)
+      return CompileResult();
+
+    Expected<std::unique_ptr<object::ObjectFile>> Obj =
+        object::ObjectFile::createObjectFile(ObjBuffer->getMemBufferRef());
+    if (!Obj) {
+      // TODO: Actually report errors helpfully.
+      consumeError(Obj.takeError());
+      return CompileResult();
+    }
+
+    return CompileResult(std::move(*Obj), std::move(ObjBuffer));
+  }
+
+  void notifyObjectCompiled(const Module &M, const MemoryBuffer &ObjBuffer) {
+    if (ObjCache)
+      ObjCache->notifyObjectCompiled(&M, ObjBuffer.getMemBufferRef());
+  }
+
   TargetMachine &TM;
+  ObjectCache *ObjCache = nullptr;
 };
 
 } // end namespace orc
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/IRCompileLayer.h b/llvm/include/llvm/ExecutionEngine/Orc/IRCompileLayer.h
index a6af0636df8..fc1db346af6 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/IRCompileLayer.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/IRCompileLayer.h
@@ -16,16 +16,9 @@
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ExecutionEngine/JITSymbol.h"
-#include "llvm/ExecutionEngine/ObjectCache.h"
-#include "llvm/Object/Binary.h"
-#include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/Error.h"
-#include "llvm/Support/MemoryBuffer.h"
-#include <algorithm>
-#include <functional>
 #include <memory>
 #include <string>
-#include <vector>
 
 namespace llvm {
 
@@ -39,25 +32,19 @@ namespace orc {
 /// immediately compiles each IR module to an object file (each IR Module is
 /// compiled separately). The resulting set of object files is then added to
 /// the layer below, which must implement the object layer concept.
-template <typename BaseLayerT> class IRCompileLayer {
-public:
-  using CompileFtor =
-      std::function<object::OwningBinary<object::ObjectFile>(Module &)>;
-
-private:
-  using ObjSetHandleT = typename BaseLayerT::ObjSetHandleT;
-
+template <typename BaseLayerT, typename CompileFtor>
+class IRCompileLayer {
 public:
   /// @brief Handle to a set of compiled modules.
-  using ModuleSetHandleT = ObjSetHandleT;
+  using ModuleSetHandleT = typename BaseLayerT::ObjHandleT;
 
   /// @brief Construct an IRCompileLayer with the given BaseLayer, which must
   ///        implement the ObjectLayer concept.
   IRCompileLayer(BaseLayerT &BaseLayer, CompileFtor Compile)
       : BaseLayer(BaseLayer), Compile(std::move(Compile)) {}
 
-  /// @brief Set an ObjectCache to query before compiling.
-  void setObjectCache(ObjectCache *NewCache) { ObjCache = NewCache; }
+  /// @brief Get a reference to the compiler functor.
+  CompileFtor& getCompiler() { return Compile; }
 
   /// @brief Compile each module in the given module set, then add the resulting
   ///        set of objects to the base layer along with the memory manager and
@@ -69,35 +56,15 @@ public:
   ModuleSetHandleT addModuleSet(ModuleSetT Ms,
                                 MemoryManagerPtrT MemMgr,
                                 SymbolResolverPtrT Resolver) {
-    std::vector<std::unique_ptr<object::OwningBinary<object::ObjectFile>>>
-      Objects;
-
-    for (const auto &M : Ms) {
-      auto Object =
-        llvm::make_unique<object::OwningBinary<object::ObjectFile>>();
-
-      if (ObjCache)
-        *Object = tryToLoadFromObjectCache(*M);
-
-      if (!Object->getBinary()) {
-        *Object = Compile(*M);
-        if (ObjCache)
-          ObjCache->notifyObjectCompiled(&*M,
-                                     Object->getBinary()->getMemoryBufferRef());
-      }
-
-      Objects.push_back(std::move(Object));
-    }
-
-    ModuleSetHandleT H =
-      BaseLayer.addObjectSet(std::move(Objects), std::move(MemMgr),
-                             std::move(Resolver));
-
-    return H;
+    assert(Ms.size() == 1);
+    using CompileResult = decltype(Compile(*Ms.front()));
+    auto Obj = std::make_shared<CompileResult>(Compile(*Ms.front()));
+    return BaseLayer.addObject(std::move(Obj), std::move(MemMgr),
+                               std::move(Resolver));
   }
 
   /// @brief Remove the module set associated with the handle H.
-  void removeModuleSet(ModuleSetHandleT H) { BaseLayer.removeObjectSet(H); }
+  void removeModuleSet(ModuleSetHandleT H) { BaseLayer.removeObject(H); }
 
   /// @brief Search for the given named symbol.
   /// @param Name The name of the symbol to search for.
@@ -128,27 +95,8 @@ public:
   }
 
 private:
-  object::OwningBinary<object::ObjectFile>
-  tryToLoadFromObjectCache(const Module &M) {
-    std::unique_ptr<MemoryBuffer> ObjBuffer = ObjCache->getObject(&M);
-    if (!ObjBuffer)
-      return object::OwningBinary<object::ObjectFile>();
-
-    Expected<std::unique_ptr<object::ObjectFile>> Obj =
-        object::ObjectFile::createObjectFile(ObjBuffer->getMemBufferRef());
-    if (!Obj) {
-      // TODO: Actually report errors helpfully.
-      consumeError(Obj.takeError());
-      return object::OwningBinary<object::ObjectFile>();
-    }
-
-    return object::OwningBinary<object::ObjectFile>(std::move(*Obj),
-                                                    std::move(ObjBuffer));
-  }
-
   BaseLayerT &BaseLayer;
   CompileFtor Compile;
-  ObjectCache *ObjCache = nullptr;
 };
 
 } // end namespace orc
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/ObjectTransformLayer.h b/llvm/include/llvm/ExecutionEngine/Orc/ObjectTransformLayer.h
index dc8c4537f48..c41c1233c0d 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/ObjectTransformLayer.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/ObjectTransformLayer.h
@@ -23,14 +23,14 @@ namespace orc {
 
 /// @brief Object mutating layer.
 ///
-///   This layer accepts sets of ObjectFiles (via addObjectSet). It
+///   This layer accepts sets of ObjectFiles (via addObject). It
 /// immediately applies the user supplied functor to each object, then adds
 /// the set of transformed objects to the layer below.
 template <typename BaseLayerT, typename TransformFtor>
 class ObjectTransformLayer {
 public:
   /// @brief Handle to a set of added objects.
-  using ObjSetHandleT = typename BaseLayerT::ObjSetHandleT;
+  using ObjHandleT = typename BaseLayerT::ObjHandleT;
 
   /// @brief Construct an ObjectTransformLayer with the given BaseLayer
   ObjectTransformLayer(BaseLayerT &BaseLayer,
@@ -42,19 +42,16 @@ public:
   ///        memory manager and symbol resolver.
   ///
   /// @return A handle for the added objects.
-  template <typename ObjSetT, typename MemoryManagerPtrT,
+  template <typename ObjPtrT, typename MemoryManagerPtrT,
             typename SymbolResolverPtrT>
-  ObjSetHandleT addObjectSet(ObjSetT Objects, MemoryManagerPtrT MemMgr,
-                             SymbolResolverPtrT Resolver) {
-    for (auto I = Objects.begin(), E = Objects.end(); I != E; ++I)
-      *I = Transform(std::move(*I));
-
-    return BaseLayer.addObjectSet(std::move(Objects), std::move(MemMgr),
-                                  std::move(Resolver));
+  ObjHandleT addObject(ObjPtrT Obj, MemoryManagerPtrT MemMgr,
+                       SymbolResolverPtrT Resolver) {
+    return BaseLayer.addObject(Transform(std::move(Obj)), std::move(MemMgr),
+                               std::move(Resolver));
   }
 
   /// @brief Remove the object set associated with the handle H.
-  void removeObjectSet(ObjSetHandleT H) { BaseLayer.removeObjectSet(H); }
+  void removeObject(ObjHandleT H) { BaseLayer.removeObject(H); }
 
   /// @brief Search for the given named symbol.
   /// @param Name The name of the symbol to search for.
@@ -72,7 +69,7 @@ public:
   /// @param ExportedSymbolsOnly If true, search only for exported symbols.
   /// @return A handle for the given named symbol, if it is found in the
   ///         given object set.
-  JITSymbol findSymbolIn(ObjSetHandleT H, const std::string &Name,
+  JITSymbol findSymbolIn(ObjHandleT H, const std::string &Name,
                          bool ExportedSymbolsOnly) {
     return BaseLayer.findSymbolIn(H, Name, ExportedSymbolsOnly);
   }
@@ -80,10 +77,10 @@ public:
   /// @brief Immediately emit and finalize the object set represented by the
   ///        given handle.
   /// @param H Handle for object set to emit/finalize.
-  void emitAndFinalize(ObjSetHandleT H) { BaseLayer.emitAndFinalize(H); }
+  void emitAndFinalize(ObjHandleT H) { BaseLayer.emitAndFinalize(H); }
 
   /// @brief Map section addresses for the objects associated with the handle H.
-  void mapSectionAddress(ObjSetHandleT H, const void *LocalAddress,
+  void mapSectionAddress(ObjHandleT H, const void *LocalAddress,
                          JITTargetAddress TargetAddr) {
     BaseLayer.mapSectionAddress(H, LocalAddress, TargetAddr);
   }
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/OrcRemoteTargetServer.h b/llvm/include/llvm/ExecutionEngine/Orc/OrcRemoteTargetServer.h
index 58b01a35852..e7b6d64931b 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/OrcRemoteTargetServer.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/OrcRemoteTargetServer.h
@@ -174,6 +174,12 @@ private:
     ArgV[0] = "<jit process>";
     for (auto &Arg : Args)
       ArgV[Idx++] = Arg.c_str();
+    ArgV[ArgC] = 0;
+    DEBUG(
+      for (int Idx = 0; Idx < ArgC; ++Idx) {
+        llvm::dbgs() << "Arg " << Idx << ": " << ArgV[Idx] << "\n";
+      }
+    );
 
     DEBUG(dbgs() << "  Calling " << format("0x%016x", Addr) << "\n");
     int Result = Fn(ArgC, ArgV.get());
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h b/llvm/include/llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h
index 81193a157f5..8dbe471e073 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h
@@ -35,19 +35,23 @@ namespace orc {
 
 class RTDyldObjectLinkingLayerBase {
 protected:
+
+  using ObjectPtr =
+    std::shared_ptr<object::OwningBinary<object::ObjectFile>>;
+
   /// @brief Holds a set of objects to be allocated/linked as a unit in the JIT.
   ///
   /// An instance of this class will be created for each set of objects added
-  /// via JITObjectLayer::addObjectSet. Deleting the instance (via
-  /// removeObjectSet) frees its memory, removing all symbol definitions that
+  /// via JITObjectLayer::addObject. Deleting the instance (via
+  /// removeObject) frees its memory, removing all symbol definitions that
   /// had been provided by this instance. Higher level layers are responsible
   /// for taking any action required to handle the missing symbols.
-  class LinkedObjectSet {
+  class LinkedObject {
   public:
-    LinkedObjectSet() = default;
-    LinkedObjectSet(const LinkedObjectSet&) = delete;
-    void operator=(const LinkedObjectSet&) = delete;
-    virtual ~LinkedObjectSet() = default;
+    LinkedObject() = default;
+    LinkedObject(const LinkedObject&) = delete;
+    void operator=(const LinkedObject&) = delete;
+    virtual ~LinkedObject() = default;
 
     virtual void finalize() = 0;
 
@@ -74,19 +78,11 @@ protected:
     bool Finalized = false;
   };
 
-  using LinkedObjectSetListT = std::list<std::unique_ptr<LinkedObjectSet>>;
+  using LinkedObjectListT = std::list<std::unique_ptr<LinkedObject>>;
 
 public:
   /// @brief Handle to a set of loaded objects.
-  using ObjSetHandleT = LinkedObjectSetListT::iterator;
-};
-
-/// @brief Default (no-op) action to perform when loading objects.
-class DoNothingOnNotifyLoaded {
-public:
-  template <typename ObjSetT, typename LoadResult>
-  void operator()(RTDyldObjectLinkingLayerBase::ObjSetHandleT, const ObjSetT &,
-                  const LoadResult &) {}
+  using ObjHandleT = LinkedObjectListT::iterator;
 };
 
 /// @brief Bare bones object linking layer.
@@ -95,46 +91,54 @@ public:
 /// object files to be loaded into memory, linked, and the addresses of their
 /// symbols queried. All objects added to this layer can see each other's
 /// symbols.
-template <typename NotifyLoadedFtor = DoNothingOnNotifyLoaded>
 class RTDyldObjectLinkingLayer : public RTDyldObjectLinkingLayerBase {
 public:
+
+  using RTDyldObjectLinkingLayerBase::ObjectPtr;
+
+  /// @brief Functor for receiving object-loaded notifications.
+  using NotifyLoadedFtor = std::function<void(ObjHandleT, const ObjectPtr &Obj,
+                                              const LoadedObjectInfo &)>;
+
   /// @brief Functor for receiving finalization notifications.
-  using NotifyFinalizedFtor = std::function<void(ObjSetHandleT)>;
+  using NotifyFinalizedFtor = std::function<void(ObjHandleT)>;
 
 private:
-  template <typename ObjSetT, typename MemoryManagerPtrT,
-            typename SymbolResolverPtrT, typename FinalizerFtor>
-  class ConcreteLinkedObjectSet : public LinkedObjectSet {
+
+
+  template <typename MemoryManagerPtrT, typename SymbolResolverPtrT,
+            typename FinalizerFtor>
+  class ConcreteLinkedObject : public LinkedObject {
   public:
-    ConcreteLinkedObjectSet(ObjSetT Objects, MemoryManagerPtrT MemMgr,
-                            SymbolResolverPtrT Resolver,
-                            FinalizerFtor Finalizer,
-                            bool ProcessAllSections)
+    ConcreteLinkedObject(ObjectPtr Obj, MemoryManagerPtrT MemMgr,
+                         SymbolResolverPtrT Resolver,
+                         FinalizerFtor Finalizer,
+                         bool ProcessAllSections)
       : MemMgr(std::move(MemMgr)),
-        PFC(llvm::make_unique<PreFinalizeContents>(std::move(Objects),
+        PFC(llvm::make_unique<PreFinalizeContents>(std::move(Obj),
                                                    std::move(Resolver),
                                                    std::move(Finalizer),
                                                    ProcessAllSections)) {
-      buildInitialSymbolTable(PFC->Objects);
+      buildInitialSymbolTable(PFC->Obj);
     }
 
-    ~ConcreteLinkedObjectSet() override {
+    ~ConcreteLinkedObject() override {
       MemMgr->deregisterEHFrames();
     }
-    
-    void setHandle(ObjSetHandleT H) {
+
+    void setHandle(ObjHandleT H) {
       PFC->Handle = H;
     }
 
     void finalize() override {
-      assert(PFC && "mapSectionAddress called on finalized LinkedObjectSet");
+      assert(PFC && "mapSectionAddress called on finalized LinkedObject");
 
       RuntimeDyld RTDyld(*MemMgr, *PFC->Resolver);
       RTDyld.setProcessAllSections(PFC->ProcessAllSections);
       PFC->RTDyld = &RTDyld;
 
       this->Finalized = true;
-      PFC->Finalizer(PFC->Handle, RTDyld, std::move(PFC->Objects),
+      PFC->Finalizer(PFC->Handle, RTDyld, std::move(PFC->Obj),
                      [&]() {
                        this->updateSymbolTable(RTDyld);
                      });
@@ -156,27 +160,27 @@ private:
 
     void mapSectionAddress(const void *LocalAddress,
                            JITTargetAddress TargetAddr) const override {
-      assert(PFC && "mapSectionAddress called on finalized LinkedObjectSet");
-      assert(PFC->RTDyld && "mapSectionAddress called on raw LinkedObjectSet");
+      assert(PFC && "mapSectionAddress called on finalized LinkedObject");
+      assert(PFC->RTDyld && "mapSectionAddress called on raw LinkedObject");
       PFC->RTDyld->mapSectionAddress(LocalAddress, TargetAddr);
     }
 
   private:
-    void buildInitialSymbolTable(const ObjSetT &Objects) {
-      for (const auto &Obj : Objects)
-        for (auto &Symbol : getObject(*Obj).symbols()) {
-          if (Symbol.getFlags() & object::SymbolRef::SF_Undefined)
-            continue;
-          Expected<StringRef> SymbolName = Symbol.getName();
-          // FIXME: Raise an error for bad symbols.
-          if (!SymbolName) {
-            consumeError(SymbolName.takeError());
-            continue;
-          }
-          auto Flags = JITSymbolFlags::fromObjectSymbol(Symbol);
-          SymbolTable.insert(
-            std::make_pair(*SymbolName, JITEvaluatedSymbol(0, Flags)));
+
+    void buildInitialSymbolTable(const ObjectPtr &Obj) {
+      for (auto &Symbol : Obj->getBinary()->symbols()) {
+        if (Symbol.getFlags() & object::SymbolRef::SF_Undefined)
+          continue;
+        Expected<StringRef> SymbolName = Symbol.getName();
+        // FIXME: Raise an error for bad symbols.
+        if (!SymbolName) {
+          consumeError(SymbolName.takeError());
+          continue;
         }
+        auto Flags = JITSymbolFlags::fromObjectSymbol(Symbol);
+        SymbolTable.insert(
+          std::make_pair(*SymbolName, JITEvaluatedSymbol(0, Flags)));
+      }
     }
 
     void updateSymbolTable(const RuntimeDyld &RTDyld) {
@@ -187,17 +191,17 @@ private:
     // Contains the information needed prior to finalization: the object files,
     // memory manager, resolver, and flags needed for RuntimeDyld.
     struct PreFinalizeContents {
-      PreFinalizeContents(ObjSetT Objects, SymbolResolverPtrT Resolver,
+      PreFinalizeContents(ObjectPtr Obj, SymbolResolverPtrT Resolver,
                           FinalizerFtor Finalizer, bool ProcessAllSections)
-        : Objects(std::move(Objects)), Resolver(std::move(Resolver)),
+        : Obj(std::move(Obj)), Resolver(std::move(Resolver)),
           Finalizer(std::move(Finalizer)),
           ProcessAllSections(ProcessAllSections) {}
 
-      ObjSetT Objects;
+      ObjectPtr Obj;
       SymbolResolverPtrT Resolver;
       FinalizerFtor Finalizer;
       bool ProcessAllSections;
-      ObjSetHandleT Handle;
+      ObjHandleT Handle;
       RuntimeDyld *RTDyld;
     };
 
@@ -205,27 +209,22 @@ private:
     std::unique_ptr<PreFinalizeContents> PFC;
   };
 
-  template <typename ObjSetT, typename MemoryManagerPtrT,
-            typename SymbolResolverPtrT, typename FinalizerFtor>
+  template <typename MemoryManagerPtrT, typename SymbolResolverPtrT,
+            typename FinalizerFtor>
   std::unique_ptr<
-    ConcreteLinkedObjectSet<ObjSetT, MemoryManagerPtrT,
-                            SymbolResolverPtrT, FinalizerFtor>>
-  createLinkedObjectSet(ObjSetT Objects, MemoryManagerPtrT MemMgr,
-                        SymbolResolverPtrT Resolver,
-                        FinalizerFtor Finalizer,
-                        bool ProcessAllSections) {
-    using LOS = ConcreteLinkedObjectSet<ObjSetT, MemoryManagerPtrT,
-                                        SymbolResolverPtrT, FinalizerFtor>;
-    return llvm::make_unique<LOS>(std::move(Objects), std::move(MemMgr),
+    ConcreteLinkedObject<MemoryManagerPtrT, SymbolResolverPtrT, FinalizerFtor>>
+  createLinkedObject(ObjectPtr Obj, MemoryManagerPtrT MemMgr,
+                     SymbolResolverPtrT Resolver,
+                     FinalizerFtor Finalizer,
+                     bool ProcessAllSections) {
+    using LOS = ConcreteLinkedObject<MemoryManagerPtrT, SymbolResolverPtrT,
+                                     FinalizerFtor>;
+    return llvm::make_unique<LOS>(std::move(Obj), std::move(MemMgr),
                                   std::move(Resolver), std::move(Finalizer),
                                   ProcessAllSections);
   }
 
 public:
-  /// @brief LoadedObjectInfo list. Contains a list of owning pointers to
-  ///        RuntimeDyld::LoadedObjectInfo instances.
-  using LoadedObjInfoList =
-      std::vector<std::unique_ptr<RuntimeDyld::LoadedObjectInfo>>;
 
   /// @brief Construct an ObjectLinkingLayer with the given NotifyLoaded,
   ///        and NotifyFinalized functors.
@@ -250,23 +249,22 @@ public:
   ///
   /// @return A handle that can be used to refer to the loaded objects (for 
   ///         symbol searching, finalization, freeing memory, etc.).
-  template <typename ObjSetT,
-            typename MemoryManagerPtrT,
+  template <typename MemoryManagerPtrT,
             typename SymbolResolverPtrT>
-  ObjSetHandleT addObjectSet(ObjSetT Objects,
-                             MemoryManagerPtrT MemMgr,
-                             SymbolResolverPtrT Resolver) {
-    auto Finalizer = [&](ObjSetHandleT H, RuntimeDyld &RTDyld,
-                         const ObjSetT &Objs,
-                         std::function<void()> LOSHandleLoad) {
-      LoadedObjInfoList LoadedObjInfos;
+  ObjHandleT addObject(ObjectPtr Obj,
+                       MemoryManagerPtrT MemMgr,
+                       SymbolResolverPtrT Resolver) {
 
-      for (auto &Obj : Objs)
-        LoadedObjInfos.push_back(RTDyld.loadObject(this->getObject(*Obj)));
+    auto Finalizer = [&](ObjHandleT H, RuntimeDyld &RTDyld,
+                         const ObjectPtr &ObjToLoad,
+                         std::function<void()> LOSHandleLoad) {
+      std::unique_ptr<RuntimeDyld::LoadedObjectInfo> Info =
+        RTDyld.loadObject(*ObjToLoad->getBinary());
 
       LOSHandleLoad();
 
-      this->NotifyLoaded(H, Objs, LoadedObjInfos);
+      if (this->NotifyLoaded)
+        this->NotifyLoaded(H, ObjToLoad, *Info);
 
       RTDyld.finalizeWithMemoryManagerLocking();
 
@@ -274,17 +272,15 @@ public:
         this->NotifyFinalized(H);
     };
 
-    auto LOS =
-      createLinkedObjectSet(std::move(Objects), std::move(MemMgr),
-                            std::move(Resolver), std::move(Finalizer),
-                            ProcessAllSections);
+    auto LO =
+      createLinkedObject(std::move(Obj), std::move(MemMgr), std::move(Resolver),
+                         std::move(Finalizer), ProcessAllSections);
     // LOS is an owning-ptr. Keep a non-owning one so that we can set the handle
     // below.
-    auto *LOSPtr = LOS.get();
+    auto *LOPtr = LO.get();
 
-    ObjSetHandleT Handle = LinkedObjSetList.insert(LinkedObjSetList.end(),
-                                                   std::move(LOS));
-    LOSPtr->setHandle(Handle);
+    ObjHandleT Handle = LinkedObjList.insert(LinkedObjList.end(), std::move(LO));
+    LOPtr->setHandle(Handle);
 
     return Handle;
   }
@@ -297,9 +293,9 @@ public:
   /// indirectly) will result in undefined behavior. If dependence tracking is
   /// required to detect or resolve such issues it should be added at a higher
   /// layer.
-  void removeObjectSet(ObjSetHandleT H) {
+  void removeObject(ObjHandleT H) {
     // How do we invalidate the symbols in H?
-    LinkedObjSetList.erase(H);
+    LinkedObjList.erase(H);
   }
 
   /// @brief Search for the given named symbol.
@@ -307,7 +303,7 @@ public:
   /// @param ExportedSymbolsOnly If true, search only for exported symbols.
   /// @return A handle for the given named symbol, if it exists.
   JITSymbol findSymbol(StringRef Name, bool ExportedSymbolsOnly) {
-    for (auto I = LinkedObjSetList.begin(), E = LinkedObjSetList.end(); I != E;
+    for (auto I = LinkedObjList.begin(), E = LinkedObjList.end(); I != E;
          ++I)
       if (auto Symbol = findSymbolIn(I, Name, ExportedSymbolsOnly))
         return Symbol;
@@ -322,13 +318,13 @@ public:
   /// @param ExportedSymbolsOnly If true, search only for exported symbols.
   /// @return A handle for the given named symbol, if it is found in the
   ///         given object set.
-  JITSymbol findSymbolIn(ObjSetHandleT H, StringRef Name,
+  JITSymbol findSymbolIn(ObjHandleT H, StringRef Name,
                          bool ExportedSymbolsOnly) {
     return (*H)->getSymbol(Name, ExportedSymbolsOnly);
   }
 
   /// @brief Map section addresses for the objects associated with the handle H.
-  void mapSectionAddress(ObjSetHandleT H, const void *LocalAddress,
+  void mapSectionAddress(ObjHandleT H, const void *LocalAddress,
                          JITTargetAddress TargetAddr) {
     (*H)->mapSectionAddress(LocalAddress, TargetAddr);
   }
@@ -336,22 +332,13 @@ public:
   /// @brief Immediately emit and finalize the object set represented by the
   ///        given handle.
   /// @param H Handle for object set to emit/finalize.
-  void emitAndFinalize(ObjSetHandleT H) {
+  void emitAndFinalize(ObjHandleT H) {
     (*H)->finalize();
   }
 
 private:
-  static const object::ObjectFile& getObject(const object::ObjectFile &Obj) {
-    return Obj;
-  }
-
-  template <typename ObjT>
-  static const object::ObjectFile&
-  getObject(const object::OwningBinary<ObjT> &Obj) {
-    return *Obj.getBinary();
-  }
 
-  LinkedObjectSetListT LinkedObjSetList;
+  LinkedObjectListT LinkedObjList;
   NotifyLoadedFtor NotifyLoaded;
   NotifyFinalizedFtor NotifyFinalized;
   bool ProcessAllSections = false;