Fix some bugs for quantization passes.

python/paddle/fluid/framework.py

@@ -1964,6 +1964,28 @@ class IrOpNode(IrNode):
         else:
             desc._set_attr(name, val)
 
+    def input_arg_names(self):
+        """
+        Return input arguments' names of this op node.
+
+        Returns:
+            list(str): input arguments' names of this op node.
+        """
+        assert self.node.op() is not None, \
+            "The node operator description cannot be None."
+        return self.node.op().input_arg_names()
+
+    def output_arg_names(self):
+        """
+        Return output arguments' names of this op node.
+
+        Returns:
+            list(str): output arguments' names of this op node.
+        """
+        assert self.node.op() is not None, \
+            "The node operator description cannot be None."
+        return self.node.op().output_arg_names()
+
     @property
     def inputs(self):
         """
@@ -2054,31 +2076,38 @@ class IrGraph(object):
         """
         return {IrOpNode(node) for node in self.graph.nodes() if node.is_op()}
 
-    def var_node(self, name):
+    def _find_var_node(self, key):
         """
-        Get a variable node by name from the graph.
+        Get a variable node by the `key` from this graph. The key
+        can be a node name or a node id.
+
+        WARNS:
+            There are some nodes may have the same name. So, be
+            cautious about using this method when you find the
+            target var node by its name.
 
         Args:
-            name(str): the name of the variable node.
+            key(str|int): The str type denotes that the target variable node's name.
+            And the int type denotes that the target variable node's id.
 
         Raises:
-            ValueError: The If input's type is not str, or this graph
-            doesn't have a variable with the giving name.
+            ValueError: If this graph doesn't have a variable with the giving name or id.
 
         Returns:
-            IrVarNode: the variable node with the giving name.
+            IrVarNode: the variable node with the giving name or id.
         """
-        if not isinstance(name, six.string_types):
-            raise TypeError(
-                "var require string as parameter, but get %s instead." %
-                (type(name)))
         target_var_node = None
         var_nodes = self.all_var_nodes()
-        for var_node in var_nodes:
-            if var_node.name() == name:
-                target_var_node = var_node
+        if isinstance(key, six.string_types):
+            for var_node in var_nodes:
+                if var_node.name() == key:
+                    target_var_node = var_node
+        elif isinstance(key, int):
+            for var_node in var_nodes:
+                if var_node.id() == key:
+                    target_var_node = var_node
         if target_var_node is None:
-            raise ValueError("var_node %s not in this graph" % name)
+            raise ValueError("var_node %s not in this graph" % key)
         return target_var_node
 
     def create_persistable_node(self, name, var_type, shape, var_dtype):