refactor code

Author: zhijxu-MS

tf2onnx/rewriter/cond_rewriter.py

@@ -127,6 +127,9 @@ def _get_output_shape_dtype(self, cond_context):
                         false_dtype
                     )
                 )
+            # in tf, the shape of different branched can be different,
+            # for example output shape of branch A can be [-1] while branch B can be [1].
+            # Under this case, we should set output shape to be [-1]
             output_shapes.append(utils.create_vague_shape_like(utils.merge_shapes(true_shape, false_shape)))
             output_dtypes.append(true_dtype)
         return output_shapes, output_dtypes

tf2onnx/tfonnx.py

@@ -475,6 +475,8 @@ def rewrite_incomplete_type_support_rs6(g, ops):
         "Div",
         "Greater",
         "IsNaN",
+        "Less",
+        "Max",
         "Min",
         "ReduceSum",
         "Slice",