In reporting step-in positions be more accurate with a position the debugger paused at

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 10de6f9e5ec001c595a0b86632599f9be9a22074..72c70f686634e797ca5581b3b44b8a745a075d41 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -12019,6 +12019,10 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_GetStepInPositions) {
   // Get the frame where the debugging is performed.
   StackFrame::Id id = UnwrapFrameId(wrapped_id);
   JavaScriptFrameIterator frame_it(isolate, id);
+  if (frame_it.done()) {

[Yang, 2013/08/26 13:52:02]

you could use RUNTIME_CHECK(!frame_it.done()) here.

[Peter.Rybin, 2013/08/31 16:58:07]

I guess you meant RUNTIME_ASSERT
Done

+    return isolate->ThrowIllegalOperation();
+  }
+
   JavaScriptFrame* frame = frame_it.frame();
 
   Handle<JSFunction> fun =
@@ -12038,11 +12042,28 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_GetStepInPositions) {
   BreakLocationIterator break_location_iterator(debug_info,
                                                 ALL_BREAK_LOCATIONS);
 
-  break_location_iterator.FindBreakLocationFromAddress(frame->pc());
+  break_location_iterator.FindBreakLocationFromAddress(frame->pc() - 1);
   int current_statement_pos = break_location_iterator.statement_position();
 
   while (!break_location_iterator.Done()) {
+    bool accept;
     if (break_location_iterator.pc() > frame->pc()) {
+      accept = true;
+    } else {
+      StackFrame::Id break_frame_id = isolate->debug()->break_frame_id();
+      // The break point is near our pc. Could be a step-in possibility,
+      // that is currently taken by active debugger call.
+      if (break_frame_id == StackFrame::NO_ID) {
+        // We are not stepping.
+        accept = false;
+      } else {
+        JavaScriptFrameIterator additional_frame_it(isolate, break_frame_id);
+        // If our frame is a top frame and we are stepping, we can do step-in
+        // at this place.
+        accept = additional_frame_it.frame()->id() == id;
+      }
+    }
+    if (accept) {
       if (break_location_iterator.IsStepInLocation(isolate)) {
         Smi* position_value = Smi::FromInt(break_location_iterator.position());
         JSObject::SetElement(array, len,