Check that function being patched has no activations on any thread stack

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index e8abdef7f5c17f27468cf1ef7901206b3dc7b281..6d3a158068f556761c7a0a9db0a51366a4867526 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -8443,6 +8443,44 @@ static Object* Runtime_LiveEditPatchFunctionPositions(Arguments args) {
 }
 
 
+static LiveEdit::FunctionPatchabilityStatus FindFunctionCodeOnStacks(
+    Handle<SharedFunctionInfo> shared) {
+  // TODO(635): check all threads, not only the current one.
+  for (StackFrameIterator it; !it.done(); it.Advance()) {
+    StackFrame* frame = it.frame();
+    if (frame->code() == shared->code()) {
+      return LiveEdit::FUNCTION_BLOCKED_ON_STACK;
+    }
+  }
+  return LiveEdit::FUNCTION_AVAILABLE_FOR_PATCH;
+}
+
+// For array of SharedFunctionInfo's (each wrapped in JSValue)
+// checks that none of them have activations on stacks (of any thread).
+// Returns array of the same length with corresponding results of
+// LiveEdit::FunctionPatchabilityStatus type.
+static Object* Runtime_LiveEditCheckStackActivations(Arguments args) {
+  ASSERT(args.length() == 1);
+  HandleScope scope;
+  CONVERT_ARG_CHECKED(JSArray, shared_array, 0);
+
+
+  int len = Smi::cast(shared_array->length())->value();
+  Handle<JSArray> result = Factory::NewJSArray(len);
+
+  for (int i = 0; i < len; i++) {
+    JSValue* wrapper = JSValue::cast(shared_array->GetElement(i));
+    Handle<SharedFunctionInfo> shared(
+        SharedFunctionInfo::cast(wrapper->value()));
+    LiveEdit::FunctionPatchabilityStatus check_res =
+        FindFunctionCodeOnStacks(shared);
+    SetElement(result, i, Handle<Smi>(Smi::FromInt(check_res)));
+  }
+
+  return *result;
+}
+
+
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 #ifdef ENABLE_LOGGING_AND_PROFILING