Disable GDBRegistrationListener

It makes emitting object extremely slow.
GDB doesn't work properly with it anyway.
GDB also often crashes because it cannot read the format.

Author: Nekotekina

lib/ExecutionEngine/GDBRegistrationListener.cpp

@@ -19,84 +19,16 @@
 using namespace llvm;
 using namespace llvm::object;
 
-// This must be kept in sync with gdb/gdb/jit.h .
-extern "C" {
-
-  typedef enum {
-    JIT_NOACTION = 0,
-    JIT_REGISTER_FN,
-    JIT_UNREGISTER_FN
-  } jit_actions_t;
-
-  struct jit_code_entry {
-    struct jit_code_entry *next_entry;
-    struct jit_code_entry *prev_entry;
-    const char *symfile_addr;
-    uint64_t symfile_size;
-  };
-
-  struct jit_descriptor {
-    uint32_t version;
-    // This should be jit_actions_t, but we want to be specific about the
-    // bit-width.
-    uint32_t action_flag;
-    struct jit_code_entry *relevant_entry;
-    struct jit_code_entry *first_entry;
-  };
-
-  // We put information about the JITed function in this global, which the
-  // debugger reads.  Make sure to specify the version statically, because the
-  // debugger checks the version before we can set it during runtime.
-  extern struct jit_descriptor __jit_debug_descriptor;
-
-  // Debuggers puts a breakpoint in this function.
-  extern "C" void __jit_debug_register_code();
-}
-
 namespace {
 
-// FIXME: lli aims to provide both, RuntimeDyld and JITLink, as the dynamic
-// loaders for it's JIT implementations. And they both offer debugging via the
-// GDB JIT interface, which builds on the two well-known symbol names below.
-// As these symbols must be unique accross the linked executable, we can only
-// define them in one of the libraries and make the other depend on it.
-// OrcTargetProcess is a minimal stub for embedding a JIT client in remote
-// executors. For the moment it seems reasonable to have the definition there
-// and let ExecutionEngine depend on it, until we find a better solution.
-//
-LLVM_ATTRIBUTE_USED void requiredSymbolDefinitionsFromOrcTargetProcess() {
-  errs() << (void *)&__jit_debug_register_code
-         << (void *)&__jit_debug_descriptor;
-}
-
-struct RegisteredObjectInfo {
-  RegisteredObjectInfo() {}
-
-  RegisteredObjectInfo(std::size_t Size, jit_code_entry *Entry,
-                       OwningBinary<ObjectFile> Obj)
-    : Size(Size), Entry(Entry), Obj(std::move(Obj)) {}
-
-  std::size_t Size;
-  jit_code_entry *Entry;
-  OwningBinary<ObjectFile> Obj;
-};
-
-// Buffer for an in-memory object file in executable memory
-typedef llvm::DenseMap<JITEventListener::ObjectKey, RegisteredObjectInfo>
-    RegisteredObjectBufferMap;
-
 /// Global access point for the JIT debugging interface designed for use with a
 /// singleton toolbox. Handles thread-safe registration and deregistration of
 /// object files that are in executable memory managed by the client of this
 /// class.
 class GDBJITRegistrationListener : public JITEventListener {
-  /// A map of in-memory object files that have been registered with the
-  /// JIT interface.
-  RegisteredObjectBufferMap ObjectBufferMap;
-
 public:
   /// Instantiates the JIT service.
-  GDBJITRegistrationListener() : ObjectBufferMap() {}
+  GDBJITRegistrationListener() {}
 
   /// Unregisters each object that was previously registered and releases all
   /// internal resources.
@@ -112,119 +44,17 @@ class GDBJITRegistrationListener : public JITEventListener {
   /// frees associated resources.
   /// Returns true if @p Object was found in ObjectBufferMap.
   void notifyFreeingObject(ObjectKey K) override;
-
-private:
-  /// Deregister the debug info for the given object file from the debugger
-  /// and delete any temporary copies.  This private method does not remove
-  /// the function from Map so that it can be called while iterating over Map.
-  void deregisterObjectInternal(RegisteredObjectBufferMap::iterator I);
 };
 
-/// Lock used to serialize all jit registration events, since they
-/// modify global variables.
-ManagedStatic<sys::Mutex> JITDebugLock;
-
-/// Do the registration.
-void NotifyDebugger(jit_code_entry* JITCodeEntry) {
-  __jit_debug_descriptor.action_flag = JIT_REGISTER_FN;
-
-  // Insert this entry at the head of the list.
-  JITCodeEntry->prev_entry = nullptr;
-  jit_code_entry* NextEntry = __jit_debug_descriptor.first_entry;
-  JITCodeEntry->next_entry = NextEntry;
-  if (NextEntry) {
-    NextEntry->prev_entry = JITCodeEntry;
-  }
-  __jit_debug_descriptor.first_entry = JITCodeEntry;
-  __jit_debug_descriptor.relevant_entry = JITCodeEntry;
-  __jit_debug_register_code();
-}
-
 GDBJITRegistrationListener::~GDBJITRegistrationListener() {
-  // Free all registered object files.
-  std::lock_guard<llvm::sys::Mutex> locked(*JITDebugLock);
-  for (RegisteredObjectBufferMap::iterator I = ObjectBufferMap.begin(),
-                                           E = ObjectBufferMap.end();
-       I != E; ++I) {
-    // Call the private method that doesn't update the map so our iterator
-    // doesn't break.
-    deregisterObjectInternal(I);
-  }
-  ObjectBufferMap.clear();
 }
 
 void GDBJITRegistrationListener::notifyObjectLoaded(
     ObjectKey K, const ObjectFile &Obj,
     const RuntimeDyld::LoadedObjectInfo &L) {
-
-  OwningBinary<ObjectFile> DebugObj = L.getObjectForDebug(Obj);
-
-  // Bail out if debug objects aren't supported.
-  if (!DebugObj.getBinary())
-    return;
-
-  const char *Buffer = DebugObj.getBinary()->getMemoryBufferRef().getBufferStart();
-  size_t      Size = DebugObj.getBinary()->getMemoryBufferRef().getBufferSize();
-
-  std::lock_guard<llvm::sys::Mutex> locked(*JITDebugLock);
-  assert(ObjectBufferMap.find(K) == ObjectBufferMap.end() &&
-         "Second attempt to perform debug registration.");
-  jit_code_entry* JITCodeEntry = new jit_code_entry();
-
-  if (!JITCodeEntry) {
-    llvm::report_fatal_error(
-      "Allocation failed when registering a JIT entry!\n");
-  } else {
-    JITCodeEntry->symfile_addr = Buffer;
-    JITCodeEntry->symfile_size = Size;
-
-    ObjectBufferMap[K] =
-        RegisteredObjectInfo(Size, JITCodeEntry, std::move(DebugObj));
-    NotifyDebugger(JITCodeEntry);
-  }
 }
 
 void GDBJITRegistrationListener::notifyFreeingObject(ObjectKey K) {
-  std::lock_guard<llvm::sys::Mutex> locked(*JITDebugLock);
-  RegisteredObjectBufferMap::iterator I = ObjectBufferMap.find(K);
-
-  if (I != ObjectBufferMap.end()) {
-    deregisterObjectInternal(I);
-    ObjectBufferMap.erase(I);
-  }
-}
-
-void GDBJITRegistrationListener::deregisterObjectInternal(
-    RegisteredObjectBufferMap::iterator I) {
-
-  jit_code_entry*& JITCodeEntry = I->second.Entry;
-
-  // Do the unregistration.
-  {
-    __jit_debug_descriptor.action_flag = JIT_UNREGISTER_FN;
-
-    // Remove the jit_code_entry from the linked list.
-    jit_code_entry* PrevEntry = JITCodeEntry->prev_entry;
-    jit_code_entry* NextEntry = JITCodeEntry->next_entry;
-
-    if (NextEntry) {
-      NextEntry->prev_entry = PrevEntry;
-    }
-    if (PrevEntry) {
-      PrevEntry->next_entry = NextEntry;
-    }
-    else {
-      assert(__jit_debug_descriptor.first_entry == JITCodeEntry);
-      __jit_debug_descriptor.first_entry = NextEntry;
-    }
-
-    // Tell the debugger which entry we removed, and unregister the code.
-    __jit_debug_descriptor.relevant_entry = JITCodeEntry;
-    __jit_debug_register_code();
-  }
-
-  delete JITCodeEntry;
-  JITCodeEntry = nullptr;
 }
 
 llvm::ManagedStatic<GDBJITRegistrationListener> GDBRegListener;