[liveedit] reimplement frame restarting.

src/debug/debug.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_DEBUG_DEBUG_H_
 #define V8_DEBUG_DEBUG_H_
 
 #include "src/allocation.h"
 #include "src/arguments.h"
 #include "src/assembler.h"
@@ skipping 293 matching lines @@
   // API facing.
   void SetEventListener(Handle<Object> callback, Handle<Object> data);
   MUST_USE_RESULT MaybeHandle<Object> Call(Handle<Object> fun,
                                            Handle<Object> data);
   Handle<Context> GetDebugContext();
   void HandleDebugBreak();
 
   // Internal logic
   bool Load();
   void Break(JavaScriptFrame* frame);
-  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,
@@ skipping 52 matching lines @@
       Handle<SharedFunctionInfo> shared,
       BreakPositionAlignment position_aligment);
 
   // Check whether a global object is the debug global object.
   bool IsDebugGlobal(JSGlobalObject* global);
 
   // Check whether this frame is just about to return.
   bool IsBreakAtReturn(JavaScriptFrame* frame);
 
   // Support for LiveEdit
-  void FramesHaveBeenDropped(StackFrame::Id new_break_frame_id,
-                             LiveEditFrameDropMode mode);
+  void ScheduleFrameRestart(StackFrame* frame);
 
   bool IsFrameBlackboxed(JavaScriptFrame* frame);
 
   // Threading support.
   char* ArchiveDebug(char* to);
   char* RestoreDebug(char* from);
   static int ArchiveSpacePerThread();
   void FreeThreadResources() { }
   void Iterate(ObjectVisitor* v);
 
@@ skipping 24 matching lines @@
   inline bool is_loaded() const { return !debug_context_.is_null(); }
   inline bool in_debug_scope() const {
     return !!base::NoBarrier_Load(&thread_local_.current_debug_scope_);
   }
   void set_break_points_active(bool v) { break_points_active_ = v; }
   bool break_points_active() const { return break_points_active_; }
 
   StackFrame::Id break_frame_id() { return thread_local_.break_frame_id_; }
   int break_id() { return thread_local_.break_id_; }
 
-  Handle<Object> return_value() { return thread_local_.return_value_; }
-  void set_return_value(Handle<Object> value) {
-    thread_local_.return_value_ = value;
-  }
+  Object* return_value() { return thread_local_.return_value_; }
+  void set_return_value(Object* value) { thread_local_.return_value_ = value; }
 
   // Support for embedding into generated code.
   Address is_active_address() {
     return reinterpret_cast<Address>(&is_active_);
   }
 
   Address hook_on_function_call_address() {
     return reinterpret_cast<Address>(&hook_on_function_call_);
   }
 
-  Address after_break_target_address() {
-    return reinterpret_cast<Address>(&after_break_target_);
-  }
-
   Address last_step_action_address() {
     return reinterpret_cast<Address>(&thread_local_.last_step_action_);
   }
 
   Address suspended_generator_address() {
     return reinterpret_cast<Address>(&thread_local_.suspended_generator_);
   }
 
+  Address restart_fp_address() {
+    return reinterpret_cast<Address>(&thread_local_.restart_fp_);
+  }
+
   StepAction last_step_action() { return thread_local_.last_step_action_; }
 
   DebugFeatureTracker* feature_tracker() { return &feature_tracker_; }
 
  private:
   explicit Debug(Isolate* isolate);
 
   void UpdateState();
   void UpdateHookOnFunctionCall();
   void Unload();
@@ skipping 110 matching lines @@
   // Trigger debug break events for all exceptions.
   bool break_on_exception_;
   // Trigger debug break events for uncaught exceptions.
   bool break_on_uncaught_exception_;
   // Termination exception because side effect check has failed.
   bool side_effect_check_failed_;
 
   // List of active debug info objects.
   DebugInfoListNode* debug_info_list_;
 
-  // 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_;
-
   // Used to collect histogram data on debugger feature usage.
   DebugFeatureTracker feature_tracker_;
 
   // Per-thread data.
   class ThreadLocal {
    public:
     // Top debugger entry.
     base::AtomicWord current_debug_scope_;
 
     // Counter for generating next break id.
@@ skipping 10 matching lines @@
 
     // Source statement position from last step next action.
     int last_statement_position_;
 
     // Frame pointer from last step next or step frame action.
     Address last_fp_;
 
     // Frame pointer of the target frame we want to arrive at.
     Address target_fp_;
 
-    // Stores the way how LiveEdit has patched the stack. It is used when
-    // debugger returns control back to user script.
-    LiveEditFrameDropMode frame_drop_mode_;
+    // Value of the accumulator at the point of entering the debugger.
+    Object* return_value_;
 
-    // Value of accumulator in interpreter frames. In non-interpreter frames
-    // this value will be the hole.
-    Handle<Object> return_value_;
+    // The suspended generator object to track when stepping.
+    Object* suspended_generator_;
 
-    Object* suspended_generator_;
+    // The new frame pointer to drop to when restarting a frame.
+    Address restart_fp_;
 
     int async_task_count_;
   };
 
   // Storage location for registers when handling debug break calls
   ThreadLocal thread_local_;
 
   Isolate* isolate_;
 
   friend class Isolate;
@@ skipping 97 matching lines @@
 class DebugCodegen : public AllStatic {
  public:
   enum DebugBreakCallHelperMode {
     SAVE_RESULT_REGISTER,
     IGNORE_RESULT_REGISTER
   };
 
   static void GenerateDebugBreakStub(MacroAssembler* masm,
                                      DebugBreakCallHelperMode mode);
 
-  // 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);
+  static void GenerateSlot(MacroAssembler* masm, RelocInfo::Mode mode);
 
+  // Builtin to drop frames to restart function.
+  static void GenerateFrameDropperTrampoline(MacroAssembler* masm);
 
-  static void GenerateSlot(MacroAssembler* masm, RelocInfo::Mode mode);
+  // Builtin to atomically (wrt deopts) handle debugger statement and
+  // drop frames to restart function if necessary.
+  static void GenerateHandleDebuggerStatement(MacroAssembler* masm);
 
   static void PatchDebugBreakSlot(Isolate* isolate, Address pc,
                                   Handle<Code> code);
   static bool DebugBreakSlotIsPatched(Address pc);
   static void ClearDebugBreakSlot(Isolate* isolate, Address pc);
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_DEBUG_DEBUG_H_