Enhance the error message of feed_op. (#23526)

paddle/fluid/operators/controlflow/feed_op.cc

@@ -28,35 +28,52 @@ class FeedOp : public framework::OperatorBase {
  private:
   void RunImpl(const framework::Scope &scope,
                const platform::Place &place) const override {
-    // get device context from pool
-    auto *dev_ctx = platform::DeviceContextPool::Instance().Get(place);
+    OP_INOUT_CHECK(HasInputs("X"), "Input", "X", "Feed");
+    OP_INOUT_CHECK(HasOutputs("Out"), "Output", "Out", "Feed");
 
     auto feed_var_name = Input("X");
     auto *feed_var = scope.FindVar(feed_var_name);
-
-    PADDLE_ENFORCE(feed_var != nullptr,
-                   "Cannot find feed_var in scope, feed_var_name is %s",
-                   feed_var_name);
+    PADDLE_ENFORCE_NOT_NULL(
+        feed_var,
+        platform::errors::NotFound(
+            "Input varibale(%s) cannot be found in scope for operator 'Feed'.",
+            feed_var_name));
 
     auto out_name = this->Output("Out");
     auto *out_var = scope.FindVar(out_name);
-    PADDLE_ENFORCE(out_var != nullptr,
-                   "Cannot find out_var in scope, out_var_name is %s",
-                   out_name);
+    PADDLE_ENFORCE_NOT_NULL(
+        out_var,
+        platform::errors::NotFound(
+            "Output variable(%s) cannot be found in scope for operator 'Feed'",
+            out_name));
 
     auto col = Attr<int>("col");
+    PADDLE_ENFORCE_GE(col, 0,
+                      platform::errors::InvalidArgument(
+                          "Expected the column index (the attribute 'col' of "
+                          "operator 'Feed') of current feeding variable to be "
+                          "no less than 0. But received column index = %d.",
+                          col));
 
-    VLOG(3) << "Feed Var " << feed_var_name << "'s " << col << " column to var "
-            << out_name;
+    VLOG(3) << "Feed variable " << feed_var_name << "'s " << col
+            << " column to variable " << out_name;
 
     auto &feed_list = feed_var->Get<framework::FeedFetchList>();
-    PADDLE_ENFORCE_LT(static_cast<size_t>(col), feed_list.size());
+    PADDLE_ENFORCE_LT(
+        static_cast<size_t>(col), feed_list.size(),
+        platform::errors::InvalidArgument(
+            "The column index of current feeding variable is expected to be "
+            "less than the length of feeding list. But received column index = "
+            "%d, the length of feeding list = %d",
+            col, feed_list.size()));
+
     auto &feed_item = feed_list.at(static_cast<size_t>(col));
     auto *out_item = out_var->GetMutable<framework::FeedFetchType>();
 
     if (platform::is_same_place(feed_item.place(), place)) {
       out_item->ShareDataWith(feed_item);
     } else {
+      auto *dev_ctx = platform::DeviceContextPool::Instance().Get(place);
       framework::TensorCopy(feed_item, place, *dev_ctx, out_item);
     }
     out_item->set_lod(feed_item.lod());
@@ -66,9 +83,13 @@ class FeedOp : public framework::OperatorBase {
 class FeedOpInfoMaker : public framework::OpProtoAndCheckerMaker {
  public:
   void Make() override {
-    AddInput("X", "The input of feed op");
-    AddOutput("Out", "The output of feed op");
-    AddAttr<int>("col", "(int) The column of feed");
+    AddInput("X",
+             "(vector<LoDTensor>) A feeding list of LoDTensor, which may have "
+             "different dimension and data type.");
+    AddOutput("Out",
+              "(LoDTensor) The LoDTensor which is a copy of the col-th feeding "
+              "object.");
+    AddAttr<int>("col", "(int) The column index of current feeding object.");
     AddComment(R"DOC(
 Feed Operator.