Merge the classes Debug and Debugger.

src/debug.h

Index: src/debug.h
diff --git a/src/debug.h b/src/debug.h
index e0f3ea09770c9266021d51b8c59f72554b511cc6..06e60523fd3b9ddd2875fab810a2d6c7b44e2c36 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -13,6 +13,7 @@
 #include "flags.h"
 #include "frames-inl.h"
 #include "hashmap.h"
+#include "liveedit.h"
 #include "platform.h"
 #include "string-stream.h"
 #include "v8threads.h"
@@ -24,7 +25,7 @@ namespace internal {
 
 
 // Forward declarations.
-class EnterDebugger;
+class DebugScope;
 
 
 // Step actions. NOTE: These values are in macros.py as well.
@@ -149,10 +150,7 @@ class BreakLocationIterator {
 // the cache is the script id.
 class ScriptCache : private HashMap {
  public:
-  explicit ScriptCache(Isolate* isolate)
-      : HashMap(HashMap::PointersMatch),
-        isolate_(isolate),
-        collected_scripts_(10) {}
+  explicit ScriptCache(Isolate* isolate);
   virtual ~ScriptCache() { Clear(); }
 
   // Add script to the cache.
@@ -202,413 +200,6 @@ class DebugInfoListNode {
   DebugInfoListNode* next_;
 };
 
-// This class contains the debugger support. The main purpose is to handle
-// setting break points in the code.
-//
-// This class controls the debug info for all functions which currently have
-// active breakpoints in them. This debug info is held in the heap root object
-// debug_info which is a FixedArray. Each entry in this list is of class
-// DebugInfo.
-class Debug {
- public:
-  bool Load();
-  void Unload();
-  bool IsLoaded() { return !debug_context_.is_null(); }
-  bool InDebugger() { return thread_local_.debugger_entry_ != NULL; }
-
-  Object* Break(Arguments args);
-  bool SetBreakPoint(Handle<JSFunction> function,
-                     Handle<Object> break_point_object,
-                     int* source_position);
-  bool SetBreakPointForScript(Handle<Script> script,
-                              Handle<Object> break_point_object,
-                              int* source_position,
-                              BreakPositionAlignment alignment);
-  void ClearBreakPoint(Handle<Object> break_point_object);
-  void ClearAllBreakPoints();
-  void FloodWithOneShot(Handle<JSFunction> function);
-  void FloodBoundFunctionWithOneShot(Handle<JSFunction> function);
-  void FloodHandlerWithOneShot();
-  void ChangeBreakOnException(ExceptionBreakType type, bool enable);
-  bool IsBreakOnException(ExceptionBreakType type);
-
-  void PromiseHandlePrologue(Handle<JSFunction> promise_getter);
-  void PromiseHandleEpilogue();
-  // Returns a promise if it does not have a reject handler.
-  Handle<Object> GetPromiseForUncaughtException();
-
-  void PrepareStep(StepAction step_action,
-                   int step_count,
-                   StackFrame::Id frame_id);
-  void ClearStepping();
-  void ClearStepOut();
-  bool IsStepping() { return thread_local_.step_count_ > 0; }
-  bool StepNextContinue(BreakLocationIterator* break_location_iterator,
-                        JavaScriptFrame* frame);
-  static Handle<DebugInfo> GetDebugInfo(Handle<SharedFunctionInfo> shared);
-  static bool HasDebugInfo(Handle<SharedFunctionInfo> shared);
-
-  void PrepareForBreakPoints();
-
-  // This function is used in FunctionNameUsing* tests.
-  Object* FindSharedFunctionInfoInScript(Handle<Script> script, int position);
-
-  // Returns whether the operation succeeded. Compilation can only be triggered
-  // if a valid closure is passed as the second argument, otherwise the shared
-  // function needs to be compiled already.
-  bool EnsureDebugInfo(Handle<SharedFunctionInfo> shared,
-                       Handle<JSFunction> function);
-
-  // Returns true if the current stub call is patched to call the debugger.
-  static bool IsDebugBreak(Address addr);
-  // Returns true if the current return statement has been patched to be
-  // a debugger breakpoint.
-  static bool IsDebugBreakAtReturn(RelocInfo* rinfo);
-
-  // Check whether a code stub with the specified major key is a possible break
-  // point location.
-  static bool IsSourceBreakStub(Code* code);
-  static bool IsBreakStub(Code* code);
-
-  // Find the builtin to use for invoking the debug break
-  static Handle<Code> FindDebugBreak(Handle<Code> code, RelocInfo::Mode mode);
-
-  static Handle<Object> GetSourceBreakLocations(
-      Handle<SharedFunctionInfo> shared,
-      BreakPositionAlignment position_aligment);
-
-  // Getter for the debug_context.
-  inline Handle<Context> debug_context() { return debug_context_; }
-
-  // Check whether a global object is the debug global object.
-  bool IsDebugGlobal(GlobalObject* global);
-
-  // Check whether this frame is just about to return.
-  bool IsBreakAtReturn(JavaScriptFrame* frame);
-
-  // Fast check to see if any break points are active.
-  inline bool has_break_points() { return has_break_points_; }
-
-  void NewBreak(StackFrame::Id break_frame_id);
-  void SetBreak(StackFrame::Id break_frame_id, int break_id);
-  StackFrame::Id break_frame_id() {
-    return thread_local_.break_frame_id_;
-  }
-  int break_id() { return thread_local_.break_id_; }
-
-  bool StepInActive() { return thread_local_.step_into_fp_ != 0; }
-  void HandleStepIn(Handle<JSFunction> function,
-                    Handle<Object> holder,
-                    Address fp,
-                    bool is_constructor);
-  Address step_in_fp() { return thread_local_.step_into_fp_; }
-  Address* step_in_fp_addr() { return &thread_local_.step_into_fp_; }
-
-  bool StepOutActive() { return thread_local_.step_out_fp_ != 0; }
-  Address step_out_fp() { return thread_local_.step_out_fp_; }
-
-  EnterDebugger* debugger_entry() {
-    return thread_local_.debugger_entry_;
-  }
-  void set_debugger_entry(EnterDebugger* entry) {
-    thread_local_.debugger_entry_ = entry;
-  }
-
-  // Check whether any of the specified interrupts are pending.
-  bool has_pending_interrupt() {
-    return thread_local_.has_pending_interrupt_;
-  }
-
-  // Set specified interrupts as pending.
-  void set_has_pending_interrupt(bool value) {
-    thread_local_.has_pending_interrupt_ = value;
-  }
-
-  // Getter and setter for the disable break state.
-  bool disable_break() { return disable_break_; }
-  void set_disable_break(bool disable_break) {
-    disable_break_ = disable_break;
-  }
-
-  // Getters for the current exception break state.
-  bool break_on_exception() { return break_on_exception_; }
-  bool break_on_uncaught_exception() {
-    return break_on_uncaught_exception_;
-  }
-
-  enum AddressId {
-    k_after_break_target_address,
-    k_restarter_frame_function_pointer
-  };
-
-  // Support for setting the address to jump to when returning from break point.
-  Address after_break_target_address() {
-    return reinterpret_cast<Address>(&thread_local_.after_break_target_);
-  }
-
-  Address restarter_frame_function_pointer_address() {
-    Object*** address = &thread_local_.restarter_frame_function_pointer_;
-    return reinterpret_cast<Address>(address);
-  }
-
-  static const int kEstimatedNofDebugInfoEntries = 16;
-  static const int kEstimatedNofBreakPointsInFunction = 16;
-
-  // Passed to MakeWeak.
-  static void HandleWeakDebugInfo(
-      const v8::WeakCallbackData<v8::Value, void>& data);
-
-  friend class Debugger;
-  friend Handle<FixedArray> GetDebuggedFunctions();  // In test-debug.cc
-  friend void CheckDebuggerUnloaded(bool check_functions);  // In test-debug.cc
-
-  // Threading support.
-  char* ArchiveDebug(char* to);
-  char* RestoreDebug(char* from);
-  static int ArchiveSpacePerThread();
-  void FreeThreadResources() { }
-
-  // Mirror cache handling.
-  void ClearMirrorCache();
-
-  // Script cache handling.
-  void CreateScriptCache();
-  void DestroyScriptCache();
-  void AddScriptToScriptCache(Handle<Script> script);
-  Handle<FixedArray> GetLoadedScripts();
-
-  // Record function from which eval was called.
-  static void RecordEvalCaller(Handle<Script> script);
-
-  // Garbage collection notifications.
-  void AfterGarbageCollection();
-
-  // Code generator routines.
-  static void GenerateSlot(MacroAssembler* masm);
-  static void GenerateCallICStubDebugBreak(MacroAssembler* masm);
-  static void GenerateLoadICDebugBreak(MacroAssembler* masm);
-  static void GenerateStoreICDebugBreak(MacroAssembler* masm);
-  static void GenerateKeyedLoadICDebugBreak(MacroAssembler* masm);
-  static void GenerateKeyedStoreICDebugBreak(MacroAssembler* masm);
-  static void GenerateCompareNilICDebugBreak(MacroAssembler* masm);
-  static void GenerateReturnDebugBreak(MacroAssembler* masm);
-  static void GenerateCallFunctionStubDebugBreak(MacroAssembler* masm);
-  static void GenerateCallConstructStubDebugBreak(MacroAssembler* masm);
-  static void GenerateCallConstructStubRecordDebugBreak(MacroAssembler* masm);
-  static void GenerateSlotDebugBreak(MacroAssembler* masm);
-  static void GeneratePlainReturnLiveEdit(MacroAssembler* masm);
-
-  // FrameDropper is a code replacement for a JavaScript frame with possibly
-  // several frames above.
-  // There is no calling conventions here, because it never actually gets
-  // called, it only gets returned to.
-  static void GenerateFrameDropperLiveEdit(MacroAssembler* masm);
-
-  // Describes how exactly a frame has been dropped from stack.
-  enum FrameDropMode {
-    // No frame has been dropped.
-    FRAMES_UNTOUCHED,
-    // The top JS frame had been calling IC stub. IC stub mustn't be called now.
-    FRAME_DROPPED_IN_IC_CALL,
-    // The top JS frame had been calling debug break slot stub. Patch the
-    // address this stub jumps to in the end.
-    FRAME_DROPPED_IN_DEBUG_SLOT_CALL,
-    // The top JS frame had been calling some C++ function. The return address
-    // gets patched automatically.
-    FRAME_DROPPED_IN_DIRECT_CALL,
-    FRAME_DROPPED_IN_RETURN_CALL,
-    CURRENTLY_SET_MODE
-  };
-
-  void FramesHaveBeenDropped(StackFrame::Id new_break_frame_id,
-                                    FrameDropMode mode,
-                                    Object** restarter_frame_function_pointer);
-
-  // Initializes an artificial stack frame. The data it contains is used for:
-  //  a. successful work of frame dropper code which eventually gets control,
-  //  b. being compatible with regular stack structure for various stack
-  //     iterators.
-  // Returns address of stack allocated pointer to restarted function,
-  // the value that is called 'restarter_frame_function_pointer'. The value
-  // at this address (possibly updated by GC) may be used later when preparing
-  // 'step in' operation.
-  static Object** SetUpFrameDropperFrame(StackFrame* bottom_js_frame,
-                                         Handle<Code> code);
-
-  static const int kFrameDropperFrameSize;
-
-  // Architecture-specific constant.
-  static const bool kFrameDropperSupported;
-
-  /**
-   * Defines layout of a stack frame that supports padding. This is a regular
-   * internal frame that has a flexible stack structure. LiveEdit can shift
-   * its lower part up the stack, taking up the 'padding' space when additional
-   * stack memory is required.
-   * Such frame is expected immediately above the topmost JavaScript frame.
-   *
-   * Stack Layout:
-   *   --- Top
-   *   LiveEdit routine frames
-   *   ---
-   *   C frames of debug handler
-   *   ---
-   *   ...
-   *   ---
-   *      An internal frame that has n padding words:
-   *      - any number of words as needed by code -- upper part of frame
-   *      - padding size: a Smi storing n -- current size of padding
-   *      - padding: n words filled with kPaddingValue in form of Smi
-   *      - 3 context/type words of a regular InternalFrame
-   *      - fp
-   *   ---
-   *      Topmost JavaScript frame
-   *   ---
-   *   ...
-   *   --- Bottom
-   */
-  class FramePaddingLayout : public AllStatic {
-   public:
-    // Architecture-specific constant.
-    static const bool kIsSupported;
-
-    // A size of frame base including fp. Padding words starts right above
-    // the base.
-    static const int kFrameBaseSize = 4;
-
-    // A number of words that should be reserved on stack for the LiveEdit use.
-    // Normally equals 1. Stored on stack in form of Smi.
-    static const int kInitialSize;
-    // A value that padding words are filled with (in form of Smi). Going
-    // bottom-top, the first word not having this value is a counter word.
-    static const int kPaddingValue;
-  };
-
- private:
-  explicit Debug(Isolate* isolate);
-
-  static bool CompileDebuggerScript(Isolate* isolate, int index);
-  void ClearOneShot();
-  void ActivateStepIn(StackFrame* frame);
-  void ClearStepIn();
-  void ActivateStepOut(StackFrame* frame);
-  void ClearStepNext();
-  // Returns whether the compile succeeded.
-  void RemoveDebugInfo(Handle<DebugInfo> debug_info);
-  void SetAfterBreakTarget(JavaScriptFrame* frame);
-  Handle<Object> CheckBreakPoints(Handle<Object> break_point);
-  bool CheckBreakPoint(Handle<Object> break_point_object);
-
-  void EnsureFunctionHasDebugBreakSlots(Handle<JSFunction> function);
-  void RecompileAndRelocateSuspendedGenerators(
-      const List<Handle<JSGeneratorObject> > &suspended_generators);
-
-  // Global handle to debug context where all the debugger JavaScript code is
-  // loaded.
-  Handle<Context> debug_context_;
-
-  // Boolean state indicating whether any break points are set.
-  bool has_break_points_;
-
-  // Cache of all scripts in the heap.
-  ScriptCache* script_cache_;
-
-  // List of active debug info objects.
-  DebugInfoListNode* debug_info_list_;
-
-  bool disable_break_;
-  bool break_on_exception_;
-  bool break_on_uncaught_exception_;
-
-  class PromiseOnStack {
-   public:
-    PromiseOnStack(Isolate* isolate,
-                   PromiseOnStack* prev,
-                   Handle<JSFunction> getter);
-    ~PromiseOnStack();
-    StackHandler* handler() { return handler_; }
-    Handle<JSFunction> getter() { return getter_; }
-    PromiseOnStack* prev() { return prev_; }
-   private:
-    Isolate* isolate_;
-    StackHandler* handler_;
-    Handle<JSFunction> getter_;
-    PromiseOnStack* prev_;
-  };
-
-  // Per-thread data.
-  class ThreadLocal {
-   public:
-    // Counter for generating next break id.
-    int break_count_;
-
-    // Current break id.
-    int break_id_;
-
-    // Frame id for the frame of the current break.
-    StackFrame::Id break_frame_id_;
-
-    // Step action for last step performed.
-    StepAction last_step_action_;
-
-    // Source statement position from last step next action.
-    int last_statement_position_;
-
-    // Number of steps left to perform before debug event.
-    int step_count_;
-
-    // Frame pointer from last step next action.
-    Address last_fp_;
-
-    // Number of queued steps left to perform before debug event.
-    int queued_step_count_;
-
-    // Frame pointer for frame from which step in was performed.
-    Address step_into_fp_;
-
-    // Frame pointer for the frame where debugger should be called when current
-    // step out action is completed.
-    Address step_out_fp_;
-
-    // Storage location for jump when exiting debug break calls.
-    Address after_break_target_;
-
-    // Stores the way how LiveEdit has patched the stack. It is used when
-    // debugger returns control back to user script.
-    FrameDropMode frame_drop_mode_;
-
-    // Top debugger entry.
-    EnterDebugger* debugger_entry_;
-
-    // Pending interrupts scheduled while debugging.
-    bool has_pending_interrupt_;
-
-    // When restarter frame is on stack, stores the address
-    // of the pointer to function being restarted. Otherwise (most of the time)
-    // stores NULL. This pointer is used with 'step in' implementation.
-    Object** restarter_frame_function_pointer_;
-
-    // When a promise is being resolved, we may want to trigger a debug event
-    // if we catch a throw.  For this purpose we remember the try-catch
-    // handler address that would catch the exception.  We also hold onto a
-    // closure that returns a promise if the exception is considered uncaught.
-    // Due to the possibility of reentry we use a linked list.
-    PromiseOnStack* promise_on_stack_;
-  };
-
-  // Storage location for registers when handling debug break calls
-  ThreadLocal thread_local_;
-  void ThreadInit();
-
-  Isolate* isolate_;
-
-  friend class Isolate;
-
-  DISALLOW_COPY_AND_ASSIGN(Debug);
-};
-
-
-DECLARE_RUNTIME_FUNCTION(Debug_Break);
 
 
 // Message delivered to the message handler callback. This is either a debugger
@@ -693,7 +284,6 @@ class CommandMessage {
   static CommandMessage New(const Vector<uint16_t>& command,
                             v8::Debug::ClientData* data);
   CommandMessage();
-  ~CommandMessage();
 
   // Deletes user data and disposes of the text.
   void Dispose();
@@ -707,6 +297,7 @@ class CommandMessage {
   v8::Debug::ClientData* client_data_;
 };
 
+
 // A Queue of CommandMessage objects.  A thread-safe version is
 // LockingCommandMessageQueue, based on this class.
 class CommandMessageQueue BASE_EMBEDDED {
@@ -728,9 +319,6 @@ class CommandMessageQueue BASE_EMBEDDED {
 };
 
 
-class MessageDispatchHelperThread;
-
-
 // LockingCommandMessageQueue is a thread-safe circular buffer of CommandMessage
 // messages.  The message data is not managed by LockingCommandMessageQueue.
 // Pointers to the data are passed in and out. Implemented by adding a
@@ -750,70 +338,202 @@ class LockingCommandMessageQueue BASE_EMBEDDED {
 };
 
 
-class Debugger {
+class PromiseOnStack {
  public:
-  void OnDebugBreak(Handle<Object> break_points_hit, bool auto_continue);
-  void OnException(Handle<Object> exception, bool uncaught);
-  void OnBeforeCompile(Handle<Script> script);
+  PromiseOnStack(Isolate* isolate,
+                 PromiseOnStack* prev,
+                 Handle<JSFunction> getter);
+  ~PromiseOnStack();
+  StackHandler* handler() { return handler_; }
+  Handle<JSFunction> getter() { return getter_; }
+  PromiseOnStack* prev() { return prev_; }
+ private:
+  Isolate* isolate_;
+  StackHandler* handler_;
+  Handle<JSFunction> getter_;
+  PromiseOnStack* prev_;
+};
+
 
+// This class contains the debugger support. The main purpose is to handle
+// setting break points in the code.
+//
+// This class controls the debug info for all functions which currently have
+// active breakpoints in them. This debug info is held in the heap root object
+// debug_info which is a FixedArray. Each entry in this list is of class
+// DebugInfo.
+class Debug {
+ public:
   enum AfterCompileFlags {
     NO_AFTER_COMPILE_FLAGS,
     SEND_WHEN_DEBUGGING
   };
+
+  // Debug event triggers.
+  void OnDebugBreak(Handle<Object> break_points_hit, bool auto_continue);
+  void OnException(Handle<Object> exception, bool uncaught);
+  void OnBeforeCompile(Handle<Script> script);
   void OnAfterCompile(Handle<Script> script,
                       AfterCompileFlags after_compile_flags);
   void OnScriptCollected(int id);
 
+  // API facing.
   void SetEventListener(Handle<Object> callback, Handle<Object> data);
   void SetMessageHandler(v8::Debug::MessageHandler handler);
-
-  // Add a debugger command to the command queue.
   void EnqueueCommandMessage(Vector<const uint16_t> command,
                              v8::Debug::ClientData* client_data = NULL);
-
-  // Check whether there are commands in the command queue.
-  bool HasCommands();
-
   // Enqueue a debugger command to the command queue for event listeners.
   void EnqueueDebugCommand(v8::Debug::ClientData* client_data = NULL);
-
   MUST_USE_RESULT MaybeHandle<Object> Call(Handle<JSFunction> fun,
                                            Handle<Object> data);
-
   Handle<Context> GetDebugContext();
+  void HandleDebugBreak();
+  void ProcessDebugMessages(bool debug_command_only);
+
+  // Internal logic
+  bool Load();
+  void Break(Arguments args, JavaScriptFrame*);
+  void SetAfterBreakTarget(JavaScriptFrame* frame);
+
+  // Scripts handling.
+  Handle<FixedArray> GetLoadedScripts();
+
+  // Break point handling.
+  bool SetBreakPoint(Handle<JSFunction> function,
+                     Handle<Object> break_point_object,
+                     int* source_position);
+  bool SetBreakPointForScript(Handle<Script> script,
+                              Handle<Object> break_point_object,
+                              int* source_position,
+                              BreakPositionAlignment alignment);
+  void ClearBreakPoint(Handle<Object> break_point_object);
+  void ClearAllBreakPoints();
+  void FloodWithOneShot(Handle<JSFunction> function);
+  void FloodBoundFunctionWithOneShot(Handle<JSFunction> function);
+  void FloodHandlerWithOneShot();
+  void ChangeBreakOnException(ExceptionBreakType type, bool enable);
+  bool IsBreakOnException(ExceptionBreakType type);
+
+  // Stepping handling.
+  void PrepareStep(StepAction step_action,
+                   int step_count,
+                   StackFrame::Id frame_id);
+  void ClearStepping();
+  void ClearStepOut();
+  bool IsStepping() { return thread_local_.step_count_ > 0; }
+  bool StepNextContinue(BreakLocationIterator* break_location_iterator,
+                        JavaScriptFrame* frame);
+  bool StepInActive() { return thread_local_.step_into_fp_ != 0; }
+  void HandleStepIn(Handle<JSFunction> function,
+                    Handle<Object> holder,
+                    Address fp,
+                    bool is_constructor);
+  bool StepOutActive() { return thread_local_.step_out_fp_ != 0; }
+
+  // Purge all code objects that have no debug break slots.
+  void PrepareForBreakPoints();
+
+  // Returns whether the operation succeeded. Compilation can only be triggered
+  // if a valid closure is passed as the second argument, otherwise the shared
+  // function needs to be compiled already.
+  bool EnsureDebugInfo(Handle<SharedFunctionInfo> shared,
+                       Handle<JSFunction> function);
+  static Handle<DebugInfo> GetDebugInfo(Handle<SharedFunctionInfo> shared);
+  static bool HasDebugInfo(Handle<SharedFunctionInfo> shared);
+
+  // This function is used in FunctionNameUsing* tests.
+  Object* FindSharedFunctionInfoInScript(Handle<Script> script, int position);
+
+  // Returns true if the current stub call is patched to call the debugger.
+  static bool IsDebugBreak(Address addr);
+  // Returns true if the current return statement has been patched to be
+  // a debugger breakpoint.
+  static bool IsDebugBreakAtReturn(RelocInfo* rinfo);
+
+  static Handle<Object> GetSourceBreakLocations(
+      Handle<SharedFunctionInfo> shared,
+      BreakPositionAlignment position_aligment);
+
+  // Check whether a global object is the debug global object.
+  bool IsDebugGlobal(GlobalObject* global);
+
+  // Check whether this frame is just about to return.
+  bool IsBreakAtReturn(JavaScriptFrame* frame);
+
+  // Promise handling.
+  void PromiseHandlePrologue(Handle<JSFunction> promise_getter);
+  void PromiseHandleEpilogue();
+
+  // Support for LiveEdit
+  void FramesHaveBeenDropped(StackFrame::Id new_break_frame_id,
+                             LiveEdit::FrameDropMode mode,
+                             Object** restarter_frame_function_pointer);
+
+  // Passed to MakeWeak.
+  static void HandleWeakDebugInfo(
+      const v8::WeakCallbackData<v8::Value, void>& data);
 
-  bool ignore_debugger() const { return ignore_debugger_; }
+  // Threading support.
+  char* ArchiveDebug(char* to);
+  char* RestoreDebug(char* from);
+  static int ArchiveSpacePerThread();
+  void FreeThreadResources() { }
+
+  // Record function from which eval was called.
+  static void RecordEvalCaller(Handle<Script> script);
+
+  // Garbage collection notifications.
+  void AfterGarbageCollection();
+
+  // Flags and states.
+  DebugScope* debugger_entry() { return thread_local_.current_debug_scope_; }
+  inline Handle<Context> debug_context() { return debug_context_; }
   void set_live_edit_enabled(bool v) { live_edit_enabled_ = v; }
   bool live_edit_enabled() const {
     return FLAG_enable_liveedit && live_edit_enabled_ ;
   }
 
-  bool is_active() { return is_active_; }
+  inline bool is_active() const { return is_active_; }
+  inline bool is_loaded() const { return !debug_context_.is_null(); }
+  inline bool has_break_points() const { return has_break_points_; }
+  inline bool in_debug_scope() const {
+    return thread_local_.current_debug_scope_ != NULL;
+  }
+  void set_disable_break(bool v) { break_disabled_ = v; }
 
-  class IgnoreScope {
-   public:
-    explicit IgnoreScope(Debugger* debugger)
-        : debugger_(debugger),
-          old_state_(debugger_->ignore_debugger_) {
-      debugger_->ignore_debugger_ = true;
-    }
-
-    ~IgnoreScope() {
-      debugger_->ignore_debugger_ = old_state_;
-    }
-
-   private:
-    Debugger* debugger_;
-    bool old_state_;
-    DISALLOW_COPY_AND_ASSIGN(IgnoreScope);
-  };
+  StackFrame::Id break_frame_id() { return thread_local_.break_frame_id_; }
+  int break_id() { return thread_local_.break_id_; }
+
+  // Support for embedding into generated code.
+  Address after_break_target_address() {
+    return reinterpret_cast<Address>(&after_break_target_);
+  }
+
+  Address restarter_frame_function_pointer_address() {
+    Object*** address = &thread_local_.restarter_frame_function_pointer_;
+    return reinterpret_cast<Address>(address);
+  }
+
+  Address step_in_fp_addr() {
+    return reinterpret_cast<Address>(&thread_local_.step_into_fp_);
+  }
 
  private:
-  explicit Debugger(Isolate* isolate);
-  ~Debugger();
+  explicit Debug(Isolate* isolate);
+
+  void UpdateState();
+  void Unload();
+  void SetNextBreakId() {
+    thread_local_.break_id_ = ++thread_local_.break_count_;
+  }
 
+  // Check whether there are commands in the command queue.
+  inline bool has_commands() const { return !command_queue_.IsEmpty(); }
+  inline bool ignore_events() const { return is_suppressed_ || !is_active_; }
+
+  // Constructors for debug event objects.
   MUST_USE_RESULT MaybeHandle<Object> MakeJSObject(
-      Vector<const char> constructor_name,
+      const char* constructor_name,
       int argc,
       Handle<Object> argv[]);
   MUST_USE_RESULT MaybeHandle<Object> MakeExecutionState();
@@ -827,19 +547,16 @@ class Debugger {
       Handle<Script> script, bool before);
   MUST_USE_RESULT MaybeHandle<Object> MakeScriptCollectedEvent(int id);
 
+  // Mirror cache handling.
+  void ClearMirrorCache();
+
+  // Returns a promise if it does not have a reject handler.
+  Handle<Object> GetPromiseForUncaughtException();
+
   void CallEventCallback(v8::DebugEvent event,
                          Handle<Object> exec_state,
                          Handle<Object> event_data,
                          v8::Debug::ClientData* client_data);
-  void CallCEventCallback(v8::DebugEvent event,
-                          Handle<Object> exec_state,
-                          Handle<Object> event_data,
-                          v8::Debug::ClientData* client_data);
-  void CallJSEventCallback(v8::DebugEvent event,
-                           Handle<Object> exec_state,
-                           Handle<Object> event_data);
-  void UpdateState();
-
   void ProcessDebugEvent(v8::DebugEvent event,
                          Handle<JSObject> event_data,
                          bool auto_continue);
@@ -847,87 +564,210 @@ class Debugger {
                             Handle<JSObject> exec_state,
                             Handle<JSObject> event_data,
                             bool auto_continue);
-
-  // Invoke the message handler function.
   void InvokeMessageHandler(MessageImpl message);
 
-  inline bool EventActive() {
-    // Check whether the message handler was been cleared.
-    // TODO(yangguo): handle loading and unloading of the debugger differently.
-    // Currently argument event is not used.
-    return !ignore_debugger_ && is_active_;
+  static bool CompileDebuggerScript(Isolate* isolate, int index);
+  void ClearOneShot();
+  void ActivateStepIn(StackFrame* frame);
+  void ClearStepIn();
+  void ActivateStepOut(StackFrame* frame);
+  void ClearStepNext();
+  // Returns whether the compile succeeded.
+  void RemoveDebugInfo(Handle<DebugInfo> debug_info);
+  Handle<Object> CheckBreakPoints(Handle<Object> break_point);
+  bool CheckBreakPoint(Handle<Object> break_point_object);
+
+  inline void AssertDebugContext() {
+    ASSERT(isolate_->context() == *debug_context());
+    ASSERT(in_debug_scope());
   }
 
-  Handle<Object> event_listener_;  // Global handle to listener.
+  void ThreadInit();
+
+  // Global handles.
+  Handle<Context> debug_context_;
+  Handle<Object> event_listener_;
   Handle<Object> event_listener_data_;
-  bool is_active_;
-  bool ignore_debugger_;  // Are we temporarily ignoring the debugger?
-  bool live_edit_enabled_;  // Enable LiveEdit.
+
   v8::Debug::MessageHandler message_handler_;
-  bool debugger_unload_pending_;  // Was message handler cleared?
 
   static const int kQueueInitialSize = 4;
-  LockingCommandMessageQueue command_queue_;
   Semaphore command_received_;  // Signaled for each command received.
+  LockingCommandMessageQueue command_queue_;
   LockingCommandMessageQueue event_command_queue_;
 
+  bool is_active_;
+  bool is_suppressed_;
+  bool live_edit_enabled_;
+  bool has_break_points_;
+  bool break_disabled_;
+  bool break_on_exception_;
+  bool break_on_uncaught_exception_;
+
+  ScriptCache* script_cache_;  // Cache of all scripts in the heap.
+  DebugInfoListNode* debug_info_list_;  // List of active debug info objects.
+
+  // Storage location for jump when exiting debug break calls.
+  // Note that this address is not GC safe.  It should be computed immediately
+  // before returning to the DebugBreakCallHelper.
+  Address after_break_target_;
+
+  // Per-thread data.
+  class ThreadLocal {
+   public:
+    // Top debugger entry.
+    DebugScope* current_debug_scope_;
+
+    // Counter for generating next break id.
+    int break_count_;
+
+    // Current break id.
+    int break_id_;
+
+    // Frame id for the frame of the current break.
+    StackFrame::Id break_frame_id_;
+
+    // Step action for last step performed.
+    StepAction last_step_action_;
+
+    // Source statement position from last step next action.
+    int last_statement_position_;
+
+    // Number of steps left to perform before debug event.
+    int step_count_;
+
+    // Frame pointer from last step next action.
+    Address last_fp_;
+
+    // Number of queued steps left to perform before debug event.
+    int queued_step_count_;
+
+    // Frame pointer for frame from which step in was performed.
+    Address step_into_fp_;
+
+    // Frame pointer for the frame where debugger should be called when current
+    // step out action is completed.
+    Address step_out_fp_;
+
+    // Stores the way how LiveEdit has patched the stack. It is used when
+    // debugger returns control back to user script.
+    LiveEdit::FrameDropMode frame_drop_mode_;
+
+    // When restarter frame is on stack, stores the address
+    // of the pointer to function being restarted. Otherwise (most of the time)
+    // stores NULL. This pointer is used with 'step in' implementation.
+    Object** restarter_frame_function_pointer_;
+
+    // When a promise is being resolved, we may want to trigger a debug event
+    // if we catch a throw.  For this purpose we remember the try-catch
+    // handler address that would catch the exception.  We also hold onto a
+    // closure that returns a promise if the exception is considered uncaught.
+    // Due to the possibility of reentry we use a linked list.
+    PromiseOnStack* promise_on_stack_;
+  };
+
+  // Storage location for registers when handling debug break calls
+  ThreadLocal thread_local_;
+
   Isolate* isolate_;
 
-  friend class EnterDebugger;
   friend class Isolate;
+  friend class DebugScope;
+  friend class DisableBreak;
+  friend class SuppressDebug;
+
+  friend Handle<FixedArray> GetDebuggedFunctions();  // In test-debug.cc
+  friend void CheckDebuggerUnloaded(bool check_functions);  // In test-debug.cc
 
-  DISALLOW_COPY_AND_ASSIGN(Debugger);
+  DISALLOW_COPY_AND_ASSIGN(Debug);
 };
 
 
-// This class is used for entering the debugger. Create an instance in the stack
-// to enter the debugger. This will set the current break state, make sure the
-// debugger is loaded and switch to the debugger context. If the debugger for
-// some reason could not be entered FailedToEnter will return true.
-class EnterDebugger BASE_EMBEDDED {
- public:
-  explicit EnterDebugger(Isolate* isolate);
-  ~EnterDebugger();
+DECLARE_RUNTIME_FUNCTION(Debug_Break);
+
 
-  // Check whether the debugger could be entered.
-  inline bool FailedToEnter() { return load_failed_; }
+// This scope is used to load and enter the debug context and create a new
+// break state.  Leaving the scope will restore the previous state.
+// On failure to load, FailedToEnter returns true.
+class DebugScope BASE_EMBEDDED {
+ public:
+  explicit DebugScope(Debug* debug);
+  ~DebugScope();
 
-  // Check whether there are any JavaScript frames on the stack.
-  inline bool HasJavaScriptFrames() { return has_js_frames_; }
+  // Check whether loading was successful.
+  inline bool failed() { return failed_; }
 
   // Get the active context from before entering the debugger.
   inline Handle<Context> GetContext() { return save_.context(); }
 
  private:
-  Isolate* isolate_;
-  EnterDebugger* prev_;  // Previous debugger entry if entered recursively.
-  bool has_js_frames_;  // Were there any JavaScript frames?
+  Isolate* isolate() { return debug_->isolate_; }
+
+  Debug* debug_;
+  DebugScope* prev_;               // Previous scope if entered recursively.
   StackFrame::Id break_frame_id_;  // Previous break frame id.
-  int break_id_;  // Previous break id.
-  bool load_failed_;  // Did the debugger fail to load?
-  SaveContext save_;  // Saves previous context.
+  int break_id_;                   // Previous break id.
+  bool failed_;                    // Did the debug context fail to load?
+  SaveContext save_;               // Saves previous context.
 };
 
 
 // Stack allocated class for disabling break.
 class DisableBreak BASE_EMBEDDED {
  public:
-  explicit DisableBreak(Isolate* isolate, bool disable_break)
-    : isolate_(isolate) {
-    prev_disable_break_ = isolate_->debug()->disable_break();
-    isolate_->debug()->set_disable_break(disable_break);
+  explicit DisableBreak(Debug* debug, bool disable_break)
+    : debug_(debug), old_state_(debug->break_disabled_) {
+    debug_->break_disabled_ = disable_break;
   }
-  ~DisableBreak() {
-    isolate_->debug()->set_disable_break(prev_disable_break_);
+  ~DisableBreak() { debug_->break_disabled_ = old_state_; }
+
+ private:
+  Debug* debug_;
+  bool old_state_;
+  DISALLOW_COPY_AND_ASSIGN(DisableBreak);
+};
+
+
+class SuppressDebug BASE_EMBEDDED {
+ public:
+  explicit SuppressDebug(Debug* debug)
+      : debug_(debug), old_state_(debug->is_suppressed_) {
+    debug_->is_suppressed_ = true;
   }
+  ~SuppressDebug() { debug_->is_suppressed_ = old_state_; }
 
  private:
-  Isolate* isolate_;
-  // The previous state of the disable break used to restore the value when this
-  // object is destructed.
-  bool prev_disable_break_;
+  Debug* debug_;
+  bool old_state_;
+  DISALLOW_COPY_AND_ASSIGN(SuppressDebug);
+};
+
+
+// Code generator routines.
+class DebugCodegen : public AllStatic {
+ public:
+  static void GenerateSlot(MacroAssembler* masm);
+  static void GenerateCallICStubDebugBreak(MacroAssembler* masm);
+  static void GenerateLoadICDebugBreak(MacroAssembler* masm);
+  static void GenerateStoreICDebugBreak(MacroAssembler* masm);
+  static void GenerateKeyedLoadICDebugBreak(MacroAssembler* masm);
+  static void GenerateKeyedStoreICDebugBreak(MacroAssembler* masm);
+  static void GenerateCompareNilICDebugBreak(MacroAssembler* masm);
+  static void GenerateReturnDebugBreak(MacroAssembler* masm);
+  static void GenerateCallFunctionStubDebugBreak(MacroAssembler* masm);
+  static void GenerateCallConstructStubDebugBreak(MacroAssembler* masm);
+  static void GenerateCallConstructStubRecordDebugBreak(MacroAssembler* masm);
+  static void GenerateSlotDebugBreak(MacroAssembler* masm);
+  static void GeneratePlainReturnLiveEdit(MacroAssembler* masm);
+
+  // FrameDropper is a code replacement for a JavaScript frame with possibly
+  // several frames above.
+  // There is no calling conventions here, because it never actually gets
+  // called, it only gets returned to.
+  static void GenerateFrameDropperLiveEdit(MacroAssembler* masm);
 };
 
+
 } }  // namespace v8::internal
 
 #endif  // V8_DEBUG_H_