refactor

Author: zhijxu-MS

tf2onnx/convert.py

@@ -14,9 +14,8 @@
 
 import tensorflow as tf
 
-from tf2onnx import optimizer
 from tf2onnx.tfonnx import process_tf_graph, tf_optimize
-from tf2onnx import constants, loader, logging, utils
+from tf2onnx import constants, loader, logging, utils, optimizer
 
 
 # pylint: disable=unused-argument
@@ -146,8 +145,6 @@ def main():
                              inputs_as_nchw=args.inputs_as_nchw)
 
     onnx_graph = optimizer.optimize_graph(g)
-    if not onnx_graph:
-        onnx_graph = g
     model_proto = onnx_graph.make_model("converted from {}".format(model_path))
 
     # write onnx graph

tf2onnx/optimizer/__init__.py

@@ -47,7 +47,7 @@ def optimize_graph(graph):
                 logger.verbose("Apply %s", name)
                 current = copy.deepcopy(graph)
                 opt = factory()
-                graph = opt.optimize(current)
+                graph = opt.optimize(current) or graph
                 continue_flag = continue_flag or opt.graph_been_opt
 
             except Exception:  # pylint: disable=broad-except