Enable stepping into callback passed to builtins (e.g. Array.forEach).

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index d8da56ced5a4bc7c9f6e9b2f23226f3f5e1bc155..60779388443b3003ee4a52371cad344e1501c5ac 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -4696,6 +4696,36 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_StoreArrayLiteralElement) {
 }
 
 
+// Check whether debugger and is about to step into the callback that is passed
+// to a built-in function such as Array.forEach.
+RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugStepIntoBuiltinCallback) {
+  if (!isolate->IsDebuggerActive()) return isolate->heap()->false_value();
+  CONVERT_ARG_CHECKED(Object, callback, 0);
+  // We do not step into the callback if it's a builtin or not even a function.
+  if (!callback->IsJSFunction() || JSFunction::cast(callback)->IsBuiltin()) {
+    return isolate->heap()->false_value();
+  }
+  return isolate->heap()->true_value();
+}
+
+
+// Set break slots for the callback function that is passed to a buil-tin

[Søren Gjesse, 2012/04/20 08:33:25]

"break slots" -> "one shot breakpoints"

[Yang, 2012/04/20 11:06:54]

Done.

+// function such as Array.forEach to enables stepping into callback functions.
+RUNTIME_FUNCTION(MaybeObject*, Runtime_PrepareBreakSlotsForCallback) {
+  Debug* debug = isolate->debug();
+  if (!debug->IsStepping()) return NULL;
+  CONVERT_ARG_CHECKED(Object, callback, 0);
+  HandleScope scope(isolate);
+  Handle<SharedFunctionInfo> shared_info(JSFunction::cast(callback)->shared());
+  // When leaving the callback, step out has been activated, but not performed
+  // if we do not leave the builtin.  To be able to step into the callback
+  // again, we need to clear the step out at this point.
+  debug->ClearStepOut();
+  debug->FloodWithOneShot(shared_info);
+  return NULL;
+}
+
+
 // Set a local property, even if it is READ_ONLY.  If the property does not
 // exist, it will be added with attributes NONE.
 RUNTIME_FUNCTION(MaybeObject*, Runtime_IgnoreAttributesAndSetProperty) {