Support 'restart call frame' debug command

src/runtime.cc

 // Copyright 2012 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 12774 matching lines @@
 RUNTIME_FUNCTION(MaybeObject*, Runtime_LiveEditCompareStrings) {
   ASSERT(args.length() == 2);
   HandleScope scope(isolate);
   CONVERT_ARG_HANDLE_CHECKED(String, s1, 0);
   CONVERT_ARG_HANDLE_CHECKED(String, s2, 1);
 
   return *LiveEdit::CompareStrings(s1, s2);
 }
 
 
+// Restarts a call frame and completely drops all frames above.
+// Returns 'true' if success or undefined or error message elseway.

[Yang, 2012/06/14 09:09:28]

Ambiguous sentence. How about "Returns true if successful. Otherwise returns
undefined or an error message."

[Peter Rybin, 2012/06/14 22:08:03]

Perfect fit for 80 columns!
Done

+RUNTIME_FUNCTION(MaybeObject*, Runtime_LiveEditRestartFrame) {
+  HandleScope scope(isolate);
+  ASSERT(args.length() == 2);
+
+  // Check arguments.
+  Object* check;
+  { MaybeObject* maybe_check = Runtime_CheckExecutionState(
+      RUNTIME_ARGUMENTS(isolate, args));
+    if (!maybe_check->ToObject(&check)) return maybe_check;
+  }
+  CONVERT_NUMBER_CHECKED(int, index, Int32, args[1]);
+  Heap* heap = isolate->heap();
+
+  // Find the relevant frame with the requested index.
+  StackFrame::Id id = isolate->debug()->break_frame_id();
+  if (id == StackFrame::NO_ID) {
+    // If there are no JavaScript stack frames return undefined.
+    return heap->undefined_value();
+  }
+
+  int count = 0;
+  JavaScriptFrameIterator it(isolate, id);
+  for (; !it.done(); it.Advance()) {
+    if (index < count + it.frame()->GetInlineCount()) break;
+    count += it.frame()->GetInlineCount();
+  }
+  if (it.done()) return heap->undefined_value();
+
+  const char* error_message = LiveEdit::RestartFrame(it.frame(), isolate->zone());

[Yang, 2012/06/14 09:09:28]

80 character limit.

[Peter Rybin, 2012/06/14 22:08:03]

Done.

+  if (error_message) {
+    return *(isolate->factory()->LookupAsciiSymbol(error_message));
+  }
+  return heap->true_value();
+}
+
+
 // A testing entry. Returns statement position which is the closest to
 // source_position.
 RUNTIME_FUNCTION(MaybeObject*, Runtime_GetFunctionCodePositionFromSource) {
   ASSERT(args.length() == 2);
   HandleScope scope(isolate);
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
   CONVERT_NUMBER_CHECKED(int32_t, source_position, Int32, args[1]);
 
   Handle<Code> code(function->code(), isolate);
 
@@ skipping 790 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal