test=develop, fix debug mode unitest, hsigmoid (#15574)

paddle/fluid/operators/hierarchical_sigmoid_op.h

@@ -136,7 +136,7 @@ class HierarchicalSigmoidOpKernel : public framework::OpKernel<T> {
     sum.mutable_data<T>(framework::make_ddim(sum_dims), ctx.GetPlace());
     auto sum_mat = EigenMatrix<T>::From(sum);
     out->mutable_data<T>(ctx.GetPlace());
-    auto out_mat = framework::EigenVector<T>::Flatten(*out);
+    auto out_mat = framework::EigenMatrix<T>::From(*out);
     if (bias) {
       bit_code->Add(*bias, pre_out);
     }