Tiny fix

paddle/framework/grad_op_builder.cc

@@ -30,19 +30,20 @@ static void TransOpArg(const OperatorBase* src_op, OperatorBase* dst_op,
                        bool is_grad) {
   const auto& src_inout =
       src_type == OpArgType::IN ? src_op->inputs_ : src_op->outputs_;
-
   auto& dst_inout =
       dst_type == OpArgType::IN ? dst_op->inputs_ : dst_op->outputs_;
-  const OpProto& proto = OpRegistry::protos().at(src_op->type_);
+
+  const OpProto& proto = OpProtos().at(src_op->type_);
   const auto& src_arg_list =
       src_type == OpArgType::IN ? proto.inputs() : proto.outputs();
 
   for (const auto& arg : src_arg_list) {
+    if (arg.no_gradient() && !is_grad) continue;
     std::string src_name = arg.name();
     std::string dst_name = is_grad ? GradVarName(src_name) : src_name;
+    dst_inout[dst_name].reserve(src_inout.at(src_name).size());
     for (auto& var_name : src_inout.at(src_name)) {
-      std::string s = is_grad ? GradVarName(var_name)
-                              : (arg.no_gradient() ? kEmptyVarName : var_name);
+      std::string s = is_grad ? GradVarName(var_name) : var_name;
       dst_inout[dst_name].emplace_back(s);
     }
   }

paddle/framework/pybind.cc

@@ -152,7 +152,7 @@ All parameter, weight, gradient are variables in Paddle.
   //! @note: Be careful! PyBind will return std::string as an unicode, not
   //! Python str. If you want a str object, you should cast them in Python.
   m.def("get_all_op_protos", []() -> std::vector<py::bytes> {
-    auto &protos = OpRegistry::protos();
+    auto &protos = OpProtos();
     std::vector<py::bytes> ret_values;
     for (auto it = protos.begin(); it != protos.end(); ++it) {
       PADDLE_ENFORCE(it->second.IsInitialized(),