Fix warnings in split_ids_op

paddle/fluid/operators/split_ids_op.h

@@ -60,7 +60,9 @@ class SplitIdsOpKernel : public framework::OpKernel<T> {
     } else if (ids_var->IsType<framework::SelectedRows>()) {
       const auto *ids_selected_rows = ctx.Input<framework::SelectedRows>("Ids");
       auto &ids_dims = ids_selected_rows->value().dims();
-      PADDLE_ENFORCE_EQ(ids_dims[0], ids_selected_rows->rows().size(), "");
+      PADDLE_ENFORCE_EQ(ids_dims[0],
+                        static_cast<int64_t>(ids_selected_rows->rows().size()),
+                        "");
       const T *ids = ids_selected_rows->value().data<T>();
       const auto &ids_rows = ids_selected_rows->rows();
       auto outs = ctx.MultiOutput<framework::SelectedRows>("Out");
@@ -77,7 +79,7 @@ class SplitIdsOpKernel : public framework::OpKernel<T> {
         framework::DDim ddim = framework::make_ddim(
             {static_cast<int64_t>(out->rows().size()), row_width});
         T *output = out->mutable_value()->mutable_data<T>(ddim, place);
-        for (size_t i = 0; i < ddim[0]; ++i) {
+        for (int64_t i = 0; i < ddim[0]; ++i) {
           memcpy(output + i * row_width, ids + out->rows()[i] * row_width,
                  row_width * sizeof(T));
         }