[Custom Op] Polish customOP optional implementation for PaddleDoc (#52368)

test/custom_op/custom_optional.cc

@@ -48,18 +48,11 @@ std::vector<paddle::Tensor> AddForward(
   PD_CHECK(x.place() == paddle::PlaceType::kCPU, "x must be a CPU Tensor.");
   paddle::Tensor out = paddle::empty(x.shape(), x.dtype(), x.place());
 
-  PD_DISPATCH_FLOATING_TYPES(
-      x.type(), "AddForward", ([&] {
   if (y) {
-          add_two_pointers<data_t>(x.data<data_t>(),
-                                   y->data<data_t>(),
-                                   out.data<data_t>(),
-                                   x.size());
+    out = x + y.get();
   } else {
-          add_two_pointers<data_t>(
-              x.data<data_t>(), x.data<data_t>(), out.data<data_t>(), x.size());
+    out = x + x;
   }
-      }));
   return {out};
 }
 
@@ -93,19 +86,13 @@ std::vector<paddle::Tensor> AddBackward(
     const paddle::optional<paddle::Tensor>& y,
     const paddle::Tensor& out_grad) {  // NOLINT
   PD_CHECK(x.place() == paddle::PlaceType::kCPU, "x must be a CPU Tensor.");
-
   paddle::Tensor x_grad = paddle::zeros(x.shape(), x.dtype(), x.place());
 
-  PD_DISPATCH_FLOATING_TYPES(
-      out_grad.type(), "AddBackward", ([&] {
-        add_one_pointer<data_t>(
-            out_grad.data<data_t>(), x_grad.data<data_t>(), out_grad.size());
-        if (!y) {
-          add_one_pointer<data_t>(
-              out_grad.data<data_t>(), x_grad.data<data_t>(), out_grad.size());
+  if (y) {
+    x_grad = out_grad;
+  } else {
+    x_grad = out_grad + out_grad;
   }
-      }));
-
   return {x_grad};
 }