[Core] check topological sorting before execution

src/finn/core/onnx_exec.py

@@ -38,6 +38,7 @@ from finn.core.modelwrapper import ModelWrapper
 from finn.core.remote_exec import remote_exec
 from finn.core.rtlsim_exec import rtlsim_exec
 from finn.custom_op.registry import getCustomOp
+import finn.analysis.topology as ta
 
 
 def execute_node(node, context, graph):
@@ -121,6 +122,11 @@ def execute_onnx(model, input_dict, return_full_exec_context=False):
 
     if not model.check_all_tensor_shapes_specified():
         raise Exception("Found unspecified tensor shapes, try infer_shapes")
+    ret = model.analysis(ta.nodes_topologically_sorted)
+    assert (
+        ret["nodes_topologically_sorted"] is True
+    ), """Nodes must be
+    topologically sorted."""
 
     graph = model.graph
     # first, we need to make sure that every variable required by the graph has