1 files changed, 247 insertions, 0 deletions
diff --git a/lib/ExecutionEngine/GDBRegistrationListener.cpp b/lib/ExecutionEngine/GDBRegistrationListener.cpp
new file mode 100644
index 0000000..8ef878c
--- /dev/null
+++ b/lib/ExecutionEngine/GDBRegistrationListener.cpp
@@ -0,0 +1,247 @@
+//===----- GDBRegistrationListener.cpp - Registers objects with GDB -------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ExecutionEngine/JITEventListener.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/Mutex.h"
+#include "llvm/Support/MutexGuard.h"
+
+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.
+  struct jit_descriptor __jit_debug_descriptor = { 1, 0, nullptr, nullptr };
+
+  // Debuggers puts a breakpoint in this function.
+  LLVM_ATTRIBUTE_NOINLINE void __jit_debug_register_code() {
+    // The noinline and the asm prevent calls to this function from being
+    // optimized out.
+#if !defined(_MSC_VER)
+    asm volatile("":::"memory");
+#endif
+  }
+
+}
+
+namespace {
+
+struct RegisteredObjectInfo {
+  RegisteredObjectInfo() {}
+
+  RegisteredObjectInfo(std::size_t Size, jit_code_entry *Entry,
+                       OwningBinary<ObjectFile> Obj)
+    : Size(Size), Entry(Entry), Obj(std::move(Obj)) {}
+
+  RegisteredObjectInfo(RegisteredObjectInfo &&Other)
+    : Size(Other.Size), Entry(Other.Entry), Obj(std::move(Other.Obj)) {}
+
+  RegisteredObjectInfo& operator=(RegisteredObjectInfo &&Other) {
+    Size = Other.Size;
+    Entry = Other.Entry;
+    Obj = std::move(Other.Obj);
+    return *this;
+  }
+
+  std::size_t Size;
+  jit_code_entry *Entry;
+  OwningBinary<ObjectFile> Obj;
+};
+
+// Buffer for an in-memory object file in executable memory
+typedef llvm::DenseMap< const char*, 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() {}
+
+  /// Unregisters each object that was previously registered and releases all
+  /// internal resources.
+  virtual ~GDBJITRegistrationListener();
+
+  /// Creates an entry in the JIT registry for the buffer @p Object,
+  /// which must contain an object file in executable memory with any
+  /// debug information for the debugger.
+  void NotifyObjectEmitted(const ObjectFile &Object,
+                           const RuntimeDyld::LoadedObjectInfo &L) override;
+
+  /// Removes the internal registration of @p Object, and
+  /// frees associated resources.
+  /// Returns true if @p Object was found in ObjectBufferMap.
+  void NotifyFreeingObject(const ObjectFile &Object) 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.
+  llvm::MutexGuard 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::NotifyObjectEmitted(
+                                       const ObjectFile &Object,
+                                       const RuntimeDyld::LoadedObjectInfo &L) {
+
+  OwningBinary<ObjectFile> DebugObj = L.getObjectForDebug(Object);
+
+  // 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();
+
+  const char *Key = Object.getMemoryBufferRef().getBufferStart();
+
+  assert(Key && "Attempt to register a null object with a debugger.");
+  llvm::MutexGuard locked(*JITDebugLock);
+  assert(ObjectBufferMap.find(Key) == 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[Key] = RegisteredObjectInfo(Size, JITCodeEntry,
+                                                std::move(DebugObj));
+    NotifyDebugger(JITCodeEntry);
+  }
+}
+
+void GDBJITRegistrationListener::NotifyFreeingObject(const ObjectFile& Object) {
+  const char *Key = Object.getMemoryBufferRef().getBufferStart();
+  llvm::MutexGuard locked(*JITDebugLock);
+  RegisteredObjectBufferMap::iterator I = ObjectBufferMap.find(Key);
+
+  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;
+
+} // end namespace
+
+namespace llvm {
+
+JITEventListener* JITEventListener::createGDBRegistrationListener() {
+  return &*GDBRegListener;
+}
+
+} // namespace llvm