support user defined quantization func and preprocess (#24720)

* add user defined func test=develop

* update test=develop

* update test=develop

* fix name conflicts test=develop

* add unittest test=develop

* change 2018 to 2020 test=develop

* add comment test=develop

* add comment for function test=develop

* fix details test=develop

* fix details test=develop

python/paddle/fluid/framework.py

@@ -3341,8 +3341,6 @@ class IrOpNode(IrNode):
         """
         assert self.node.op() is not None, \
             "The node operator description can not be None."
-        print("op: {}, old: {}, new: {}\n".format(self.node.op().type(
-        ), old_output_name, new_output_name))
         self.node.op()._rename_output(old_output_name, new_output_name)
 
     def input(self, name):
@@ -3566,6 +3564,12 @@ class IrGraph(object):
         var_desc.set_dtype(var_dtype)
         return IrVarNode(self.graph.create_var_node(var_desc))
 
+    def create_control_dep_var(self):
+        """
+        create a control var
+        """
+        return IrVarNode(self.graph.create_control_dep_var())
+
     def create_var_node_from_desc(self, var_desc):
         """
         Create a variable node by using an existing VarDesc in the graph.