LiveEdit: Support debug break slots in frame dropping implementation

src/liveedit.cc

 // Copyright 2010 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 1169 matching lines @@
   return change;
 }
 
 
 // Removes specified range of frames from stack. There may be 1 or more
 // frames in range. Anyway the bottom frame is restarted rather than dropped,
 // and therefore has to be a JavaScript frame.
 // Returns error message or NULL.
 static const char* DropFrames(Vector<StackFrame*> frames,
                               int top_frame_index,
-                              int bottom_js_frame_index) {
+                              int bottom_js_frame_index,
+                              Debug::FrameDropMode* mode) {
+  if (Debug::kFrameDropperFrameSize < 0) {
+    return "Stack manipulations are not supported in this architecture.";
+  }
+
   StackFrame* pre_top_frame = frames[top_frame_index - 1];
   StackFrame* top_frame = frames[top_frame_index];
   StackFrame* bottom_js_frame = frames[bottom_js_frame_index];
 
   ASSERT(bottom_js_frame->is_java_script());
 
   // Check the nature of the top frame.
   if (pre_top_frame->code()->is_inline_cache_stub() &&
       pre_top_frame->code()->ic_state() == DEBUG_BREAK) {
     // OK, we can drop inline cache calls.
+    *mode = Debug::FRAME_DROPPED_IN_IC_CALL;
+  } else if (pre_top_frame->code() == Debug::debug_break_slot()) {
+    // OK, we can drop debug break slot.
+    *mode = Debug::FRAME_DROPPED_IN_DEBUG_SLOT_CALL;
   } else if (pre_top_frame->code() ==
       Builtins::builtin(Builtins::FrameDropper_LiveEdit)) {
     // OK, we can drop our own code.
+    *mode = Debug::FRAME_DROPPED_IN_DIRECT_CALL;
   } else if (pre_top_frame->code()->kind() == Code::STUB &&
       pre_top_frame->code()->major_key()) {
-    // Unit Test entry, it's fine, we support this case.
+    // Entry from our unit tests, it's fine, we support this case.
+    *mode = Debug::FRAME_DROPPED_IN_DIRECT_CALL;
   } else {
     return "Unknown structure of stack above changing function";
   }
 
   Address unused_stack_top = top_frame->sp();
   Address unused_stack_bottom = bottom_js_frame->fp()
       - Debug::kFrameDropperFrameSize * kPointerSize  // Size of the new frame.
       + kPointerSize;  // Bigger address end is exclusive.
 
   if (unused_stack_top > unused_stack_bottom) {
@@ skipping 92 matching lines @@
   if (!do_drop) {
     // We are in check-only mode.
     return NULL;
   }
 
   if (!target_frame_found) {
     // Nothing to drop.
     return NULL;
   }
 
+  Debug::FrameDropMode drop_mode = Debug::FRAMES_UNTOUCHED;
   const char* error_message = DropFrames(frames, top_frame_index,
-                                         bottom_js_frame_index);
+                                         bottom_js_frame_index, &drop_mode);
 
   if (error_message != NULL) {
     return error_message;
   }
 
   // Adjust break_frame after some frames has been dropped.
   StackFrame::Id new_id = StackFrame::NO_ID;
   for (int i = bottom_js_frame_index + 1; i < frames.length(); i++) {
     if (frames[i]->type() == StackFrame::JAVA_SCRIPT) {
       new_id = frames[i]->id();
       break;
     }
   }
-  Debug::FramesHaveBeenDropped(new_id);
+  Debug::FramesHaveBeenDropped(new_id, drop_mode);
 
   // Replace "blocked on active" with "replaced on active" status.
   for (int i = 0; i < array_len; i++) {
     if (result->GetElement(i) ==
         Smi::FromInt(LiveEdit::FUNCTION_BLOCKED_ON_ACTIVE_STACK)) {
       result->SetElement(i, Smi::FromInt(
           LiveEdit::FUNCTION_REPLACED_ON_ACTIVE_STACK));
     }
   }
   return NULL;
@@ skipping 114 matching lines @@
 
 bool LiveEditFunctionTracker::IsActive() {
   return false;
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 
 } }  // namespace v8::internal