[Orc] Add a method for ObjectLinkingLayer to return ownership of object buffers.

RTDyldObjectLinkingLayer allowed clients to register a NotifyEmitted function to
reclaim ownership of object buffers once they had been linked. This patch adds
similar functionality to ObjectLinkingLayer: Clients can now optionally call the
ObjectLinkingLayer::setReturnObjectBuffer method to register a function that
will be called when discarding object buffers. If set, this function will be
called to return ownership of the object regardless of whether the link
succeeded or failed.

Use cases for this function include debug dumping (it provides a way to dump
all objects linked into JIT'd code) and object re-use (e.g. storing an
object in a cache).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@374951 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h b/include/llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h
index 0605ee3bb0be4cb069e33cea01aa2cfe42b0fc0f..caf8e707516d25e6b2f24d67064cda88b318b24e 100644 (file)
--- a/include/llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h
+++ b/include/llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h
@@ -73,6 +73,9 @@ public:
     virtual Error notifyRemovingAllModules() { return Error::success(); }
   };
 
+  using ReturnObjectBufferFunction =
+      std::function<void(std::unique_ptr<MemoryBuffer>)>;
+
   /// Construct an ObjectLinkingLayer with the given NotifyLoaded,
   /// and NotifyEmitted functors.
   ObjectLinkingLayer(ExecutionSession &ES,
@@ -81,6 +84,13 @@ public:
   /// Destruct an ObjectLinkingLayer.
   ~ObjectLinkingLayer();
 
+  /// Set an object buffer return function. By default object buffers are
+  /// deleted once the JIT has linked them. If a return function is set then
+  /// it will be called to transfer ownership of the buffer instead.
+  void setReturnObjectBuffer(ReturnObjectBufferFunction ReturnObjectBuffer) {
+    this->ReturnObjectBuffer = std::move(ReturnObjectBuffer);
+  }
+
   /// Add a pass-config modifier.
   ObjectLinkingLayer &addPlugin(std::unique_ptr<Plugin> P) {
     std::lock_guard<std::mutex> Lock(LayerMutex);
@@ -138,6 +148,7 @@ private:
   jitlink::JITLinkMemoryManager &MemMgr;
   bool OverrideObjectFlags = false;
   bool AutoClaimObjectSymbols = false;
+  ReturnObjectBufferFunction ReturnObjectBuffer;
   DenseMap<VModuleKey, AllocPtr> TrackedAllocs;
   std::vector<AllocPtr> UntrackedAllocs;
   std::vector<std::unique_ptr<Plugin>> Plugins;

diff --git a/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp b/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
index 952ca6071ffb8a2685f6545a6afbaec2d9e2ff3a..874decb2ade0bc9569b73b8af306def16794b92a 100644 (file)
--- a/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
+++ b/lib/ExecutionEngine/Orc/ObjectLinkingLayer.cpp
@@ -29,6 +29,13 @@ public:
                                    std::unique_ptr<MemoryBuffer> ObjBuffer)
       : Layer(Layer), MR(std::move(MR)), ObjBuffer(std::move(ObjBuffer)) {}
 
+  ~ObjectLinkingLayerJITLinkContext() {
+    // If there is an object buffer return function then use it to
+    // return ownership of the buffer.
+    if (Layer.ReturnObjectBuffer)
+      Layer.ReturnObjectBuffer(std::move(ObjBuffer));
+  }
+
   JITLinkMemoryManager &getMemoryManager() override { return Layer.MemMgr; }
 
   MemoryBufferRef getObjectBuffer() const override {