LiveEdit: Support debug break slots in frame dropping implementation

src/debug.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 382 matching lines @@
   static void GenerateConstructCallDebugBreak(MacroAssembler* masm);
   static void GenerateReturnDebugBreak(MacroAssembler* masm);
   static void GenerateStubNoRegistersDebugBreak(MacroAssembler* masm);
   static void GenerateSlotDebugBreak(MacroAssembler* masm);
   static void GeneratePlainReturnLiveEdit(MacroAssembler* masm);
   static void GenerateFrameDropperLiveEdit(MacroAssembler* masm);
 
   // Called from stub-cache.cc.
   static void GenerateCallICDebugBreak(MacroAssembler* masm);
 
-  static void FramesHaveBeenDropped(StackFrame::Id new_break_frame_id);
+  // 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
+  };
+
+  static void FramesHaveBeenDropped(StackFrame::Id new_break_frame_id,
+                                    FrameDropMode mode);
 
   static void SetUpFrameDropperFrame(StackFrame* bottom_js_frame,
                                      Handle<Code> code);
   static const int kFrameDropperFrameSize;
 
  private:
   static bool CompileDebuggerScript(int index);
   static void ClearOneShot();
   static void ActivateStepIn(StackFrame* frame);
   static void ClearStepIn();
@@ skipping 50 matching lines @@
     // 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_;
 
-    // Indicates that LiveEdit has patched the stack.
-    bool frames_are_dropped_;
+    // 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.
     int pending_interrupts_;
   };
 
   // Storage location for registers when handling debug break calls
   static JSCallerSavedBuffer registers_;
@@ skipping 463 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(MessageDispatchHelperThread);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 #endif  // V8_DEBUG_H_