Support stepping out for recursive functions

src/runtime.cc

 // Copyright 2006-2009 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 6915 matching lines @@
       static_cast<ExceptionBreakType>(NumberToUint32(args[0]));
   bool enable = args[1]->ToBoolean()->IsTrue();
   Debug::ChangeBreakOnException(type, enable);
   return Heap::undefined_value();
 }
 
 
 // Prepare for stepping
 // args[0]: break id for checking execution state
 // args[1]: step action from the enumeration StepAction
-// args[2]: number of times to perform the step
+// args[2]: number of times to perform the step, for step out it is the number
+//          of frames to step down.
 static Object* Runtime_PrepareStep(Arguments args) {
   HandleScope scope;
   ASSERT(args.length() == 3);
   // Check arguments.
   Object* check = Runtime_CheckExecutionState(args);
   if (check->IsFailure()) return check;
   if (!args[1]->IsNumber() || !args[2]->IsNumber()) {
     return Top::Throw(Heap::illegal_argument_symbol());
   }
 
   // Get the step action and check validity.
   StepAction step_action = static_cast<StepAction>(NumberToInt32(args[1]));
   if (step_action != StepIn &&
       step_action != StepNext &&
       step_action != StepOut &&
       step_action != StepInMin &&
       step_action != StepMin) {
     return Top::Throw(Heap::illegal_argument_symbol());
   }
 
   // Get the number of steps.
   int step_count = NumberToInt32(args[2]);
   if (step_count < 1) {
     return Top::Throw(Heap::illegal_argument_symbol());
   }
 
+  // Clear all current stepping setup.
+  Debug::ClearStepping();
+
   // Prepare step.
   Debug::PrepareStep(static_cast<StepAction>(step_action), step_count);
   return Heap::undefined_value();
 }
 
 
 // Clear all stepping set by PrepareStep.
 static Object* Runtime_ClearStepping(Arguments args) {
   HandleScope scope;
   ASSERT(args.length() == 0);
@@ skipping 719 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal