   const Shape w_shape = w.shape();
   const Shape y_shape = y.shape();
 
-  // Sets device.
+  // Sets target device.
   CUDA_CALL(::cudaSetDevice(dev_id_));
 
   // Makes descriptors.

        x_desc.get(), w_desc.get(), conv_desc.get(), y_desc.get(),
        CUDNN_CONVOLUTION_FWD_PREFER_FASTEST, 0, &algo));

  // Obtains workspace.
  std::size_t ws_size;
  CUDNN_CALL(::cudnnGetConvolutionForwardWorkspaceSize(
        state_->cudnn.get(),

      y_ptr += y_shift;
    }
  } else {
    CUDNN_CALL(::cudnnConvolutionForward(
          state_->cudnn.get(),
          &alpha, x_desc.get(), x_ptr, w_desc.get(), w_ptr,
          conv_desc.get(), algo, ws_ptr.get(), ws_size,
