Resize output ddims and rows

Author: velconia

paddle/fluid/operators/clip_by_norm_op.h

@@ -33,12 +33,14 @@ class ClipByNormKernel : public framework::OpKernel<T> {
   void Compute(const framework::ExecutionContext& context) const override {
     auto max_norm = context.Attr<T>("max_norm");
     auto in_var = context.InputVar("X");
-    auto* output = context.Output<Tensor>("Out");
-    output->mutable_data<T>(context.GetPlace());
 
+    Tensor* output = nullptr;
     const Tensor* input = nullptr;
     if (in_var->IsType<framework::LoDTensor>()) {
       input = context.Input<Tensor>("X");
+
+      output = context.Output<Tensor>("Out");
+      output->mutable_data<T>(context.GetPlace());
     } else if (in_var->IsType<framework::SelectedRows>()) {
       auto* x = context.Input<framework::SelectedRows>("X");
 
@@ -50,6 +52,11 @@ class ClipByNormKernel : public framework::OpKernel<T> {
       merge_func(context.template device_context<DeviceContext>(), *x,
                  merged_input);
       input = &(merged_input->value());
+
+      auto* output_selected_rows = context.Output<SelectedRows>("Out");
+      output_selected_rows->set_rows(merged_input.rows());
+      output = output_selected_rows->mutable_data();
+      output->Resize(framework::make_ddim(merged_input.value().dims()));
     } else {
       PADDLE_THROW("Unexpected branch, input variable type is %s",
                    in_var->Type().name());