LiveEdit: Support debug break slots in frame dropping implementation

src/debug.cc

 // 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 836 matching lines @@
 void Debug::Iterate(ObjectVisitor* v) {
   v->VisitPointer(BitCast<Object**, Code**>(&(debug_break_return_)));
   v->VisitPointer(BitCast<Object**, Code**>(&(debug_break_slot_)));
 }
 
 
 Object* Debug::Break(Arguments args) {
   HandleScope scope;
   ASSERT(args.length() == 0);
 
-  thread_local_.frames_are_dropped_ = false;
+  thread_local_.frame_drop_mode_ = FRAMES_UNTOUCHED;
 
   // Get the top-most JavaScript frame.
   JavaScriptFrameIterator it;
   JavaScriptFrame* frame = it.frame();
 
   // Just continue if breaks are disabled or debugger cannot be loaded.
   if (disable_break() || !Load()) {
     SetAfterBreakTarget(frame);
     return Heap::undefined_value();
   }
@@ skipping 57 matching lines @@
     StepAction step_action = thread_local_.last_step_action_;
     int step_count = thread_local_.step_count_;
 
     // Clear all current stepping setup.
     ClearStepping();
 
     // Set up for the remaining steps.
     PrepareStep(step_action, step_count);
   }
 
-  if (thread_local_.frames_are_dropped_) {
-    // We must have been calling IC stub. Do not return there anymore.
+  if (thread_local_.frame_drop_mode_ == FRAMES_UNTOUCHED) {
+    SetAfterBreakTarget(frame);
+  } else if (thread_local_.frame_drop_mode_ == FRAME_DROPPED_IN_IC_CALL) {
+    // We must have been calling IC stub. Do not go there anymore.
     Code* plain_return = Builtins::builtin(Builtins::PlainReturn_LiveEdit);
     thread_local_.after_break_target_ = plain_return->entry();
+  } else if (thread_local_.frame_drop_mode_ ==
+      FRAME_DROPPED_IN_DEBUG_SLOT_CALL) {
+    // Debug break slot stub does not return normally, instead it manually
+    // cleans the stack and jumps. We should patch the jump address.
+    Code* plain_return = Builtins::builtin(Builtins::FrameDropper_LiveEdit);
+    thread_local_.after_break_target_ = plain_return->entry();
+  } else if (thread_local_.frame_drop_mode_ == FRAME_DROPPED_IN_DIRECT_CALL) {
+    // Nothing to do, after_break_target is not used here.
   } else {
-    SetAfterBreakTarget(frame);
+    UNREACHABLE();
   }
 
   return Heap::undefined_value();
 }
 
 
 // Check the break point objects for whether one or more are actually
 // triggered. This function returns a JSArray with the break point objects
 // which is triggered.
 Handle<Object> Debug::CheckBreakPoints(Handle<Object> break_point_objects) {
@@ skipping 791 matching lines @@
     if (RelocInfo::IsJSReturn(it.rinfo()->rmode())) {
       return (it.rinfo()->pc() ==
           addr - Assembler::kPatchReturnSequenceAddressOffset);
     }
     it.next();
   }
   return false;
 }
 
 
-void Debug::FramesHaveBeenDropped(StackFrame::Id new_break_frame_id) {
-  thread_local_.frames_are_dropped_ = true;
+void Debug::FramesHaveBeenDropped(StackFrame::Id new_break_frame_id,
+                                  FrameDropMode mode) {
+  thread_local_.frame_drop_mode_ = mode;
   thread_local_.break_frame_id_ = new_break_frame_id;
 }
 
 
 bool Debug::IsDebugGlobal(GlobalObject* global) {
   return IsLoaded() && global == Debug::debug_context()->global();
 }
 
 
 void Debug::ClearMirrorCache() {
@@ skipping 1158 matching lines @@
     {
       Locker locker;
       Debugger::CallMessageDispatchHandler();
     }
   }
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal