Fix FPE of label smooth op (#35861)

paddle/fluid/operators/label_smooth_op.h

@@ -29,22 +29,23 @@ class LabelSmoothKernel : public framework::OpKernel<T> {
     auto* dist_t = ctx.Input<framework::Tensor>("PriorDist");
     auto label_dim = in_t->dims()[in_t->dims().size() - 1];
     out_t->mutable_data<T>(ctx.GetPlace());
-
+    if (label_dim != 0) {
       auto epsilon = ctx.Attr<float>("epsilon");
       auto out = framework::EigenVector<T>::Flatten(*out_t);
       auto in = framework::EigenVector<T>::Flatten(*in_t);
       auto& dev = *ctx.template device_context<DeviceContext>().eigen_device();
       if (dist_t) {
         auto dist = framework::EigenVector<T>::Flatten(*dist_t);
-      out.device(dev) =
-          static_cast<T>(1 - epsilon) * in +
+        out.device(dev) = static_cast<T>(1 - epsilon) * in +
                           static_cast<T>(epsilon) *
-              dist.broadcast(Eigen::DSizes<int, 1>(in_t->numel() / label_dim));
+                              dist.broadcast(Eigen::DSizes<int, 1>(
+                                  in_t->numel() / label_dim));
       } else {
         out.device(dev) = static_cast<T>(1 - epsilon) * in +
                           static_cast<T>(epsilon / label_dim);
       }
     }
+  }
 };
 
 template <typename DeviceContext, typename T>
@@ -54,7 +55,8 @@ class LabelSmoothGradKernel : public framework::OpKernel<T> {
     auto* d_out_t = ctx.Input<framework::Tensor>(framework::GradVarName("Out"));
     auto* d_in_t = ctx.Output<framework::Tensor>(framework::GradVarName("X"));
     d_in_t->mutable_data<T>(ctx.GetPlace());
-
+    auto d_out_dim = d_out_t->dims()[d_out_t->dims().size() - 1];
+    if (d_out_dim != 0) {
       auto d_out = framework::EigenVector<T>::Flatten(*d_out_t);
       auto d_in = framework::EigenVector<T>::Flatten(*d_in_t);
 
@@ -62,6 +64,7 @@ class LabelSmoothGradKernel : public framework::OpKernel<T> {
       auto& dev = *ctx.template device_context<DeviceContext>().eigen_device();
       d_in.device(dev) = static_cast<T>(1 - epsilon) * d_out;
     }
+  }
 };
 }  // namespace operators
 }  // namespace paddle