enhance: if graph been optimized, then optimzers should be run again.

Author: zhijxu-MS

tf2onnx/optimizer/__init__.py

@@ -39,14 +39,21 @@ def optimize_graph(graph):
 
     before = graph.dump_node_statistics()
     opts = _get_optimizers()
-    for name, factory in opts.items():
-        try:
-            logger.verbose("Apply %s", name)
-            current = copy.deepcopy(graph)
-            graph = factory().optimize(current)
-        except Exception:  # pylint: disable=broad-except
-            # if current optimizer fails, continue with other optimizers
-            logger.warning("Failed to apply %s", name, exc_info=1)
+    continue_flag = True
+    while continue_flag:
+        continue_flag = False
+        for name, factory in opts.items():
+            try:
+                logger.verbose("Apply %s", name)
+                current = copy.deepcopy(graph)
+                opt = factory()
+                graph = opt.optimize(current)
+                if not continue_flag:
+                    continue_flag = opt.graph_been_opt
+
+            except Exception:  # pylint: disable=broad-except
+                # if current optimizer fails, continue with other optimizers
+                logger.warning("Failed to apply %s", name, exc_info=1)
 
     after = graph.dump_node_statistics()
     diff = copy.deepcopy(after)

tf2onnx/optimizer/const_fold_optimizer.py

@@ -42,6 +42,7 @@ def _optimize_at_current_graph_level(self, graph):
                     continue
                 if self._fold_node(op, graph):
                     graph_changed = True
+                    self.graph_been_opt = True
         return graph
 
     @staticmethod

tf2onnx/optimizer/identity_optimizer.py

@@ -39,6 +39,8 @@ def _optimize_at_current_graph_level(self, g):
                 else:
                     ret = self._handle_non_graph_output_identity(g, n)
                 has_update = ret
+                if ret:
+                    self.graph_been_opt = True
         return g
 
     @staticmethod

tf2onnx/optimizer/loop_optimizer.py

@@ -32,6 +32,7 @@ def _optimize_at_current_graph_level(self, g):
                 has_update_tmp = self._try_move_transpose_out_of_body_graph(n)
                 if has_update_tmp:
                     has_update = True
+                    self.graph_been_opt = True
         return g
 
     @staticmethod

tf2onnx/optimizer/merge_duplicated_nodes_optimizer.py

@@ -32,6 +32,8 @@ def _optimize_at_current_graph_level(self, graph):
         while self._graph_can_be_optimized:
             self._graph_can_be_optimized = False
             self._merge_duplicated_nodes(graph)
+            if self._graph_can_be_optimized:
+                self.graph_been_opt = True
         return graph
 
     def _merge_duplicated_nodes(self, graph):

tf2onnx/optimizer/optimizer_base.py

@@ -16,6 +16,7 @@ class GraphOptimizerBase(object):
 
     def __init__(self):
         self._logger = logging.getLogger('.'.join(__name__.split('.')[:-1] + [self.__class__.__name__]))
+        self.graph_been_opt = False
 
     @property
     def logger(self):

tf2onnx/optimizer/transpose_optimizer.py

@@ -147,6 +147,7 @@ def _optimize_at_current_graph_level(self, graph):
                 if is_nhwc_transpose(n):
                     if self._handle_nhwc_tranpose(n):
                         no_action = False
+                        self.graph_been_opt = True
                         iteration_cnt += 1
                         # need break, because handler may change nodes set, making the n stale object
                         # referencing already deleted elements