diff --git a/paddle/fluid/operators/math/matrix_bit_code.cc b/paddle/fluid/operators/math/matrix_bit_code.cc
index 88279f8d8a781ac3a7291572b40392cd0a7d17e0..090c0cca366074958c5189e0d203116cc36fd68d 100644
--- a/paddle/fluid/operators/math/matrix_bit_code.cc
+++ b/paddle/fluid/operators/math/matrix_bit_code.cc
@@ -119,6 +119,33 @@ void MatrixBitCodeFunctor<T>::MulGradWeight(const framework::Tensor& tmat,
   }
 }
 
+// template <typename T>
+// void MatrixBitCodeFunctor<T>::MulGradSparseWeight(const framework::Tensor&
+// tmat,
+//                                             framework::SelectedRows* weight,
+//                                             const framework::Tensor& input) {
+//   size_t num_samples = tmat.dims()[0];
+//   size_t input_width = input.dims()[1];
+//   size_t tmat_width = tmat.dims()[1];
+//   size_t weight_width = weight->dims()[1];
+//   auto tmat_value = tmat.data<T>();
+//   auto weight_value = weight->data<T>();
+//   auto input_value = input.data<T>();
+//   for (size_t i = 0; i < num_samples; ++i) {
+//     auto code = code_table->get_code(i);
+//     int code_length = code->get_length();
+//     for (int j = 0; j < code_length; ++j) {
+//       // size_t index = code->calc_index(j);
+
+//       for (size_t k = 0; k < input_width; ++k) {
+//         weight_value[j * weight_width + k] +=
+//             tmat_value[i * tmat_width + j] * input_value[input_width * i +
+//             k];
+//       }
+//     }
+//   }
+// }
+
 template <typename T>
 void MatrixBitCodeFunctor<T>::MulGradError(const framework::Tensor& tmat,
                                            const framework::Tensor& weight,