Make import_r as prune_r, this would make the code faster during opt.

theano/gof/fg.py

@@ -131,7 +131,8 @@ class FunctionGraph(utils.object2):
             self.__setup_r__(input)
             self.variables.add(input)
 
-        self.__import_r__(outputs, reason="init")
+        for output in outputs:
+            self.__import_r__(output, reason="init")
         for i, output in enumerate(outputs):
             output.clients.append(('output', i))
 
@@ -246,23 +247,23 @@ class FunctionGraph(utils.object2):
         return False
 
     ### import ###
-    def __import_r__(self, variables, reason):
+    def __import_r__(self, variable, reason):
         global NullType
         if NullType is None:
             from null_type import NullType
         # Imports the owners of the variables
-        for apply_node in [r.owner for r in variables if r.owner is not None]:
-            if apply_node not in self.apply_nodes:
-                self.__import__(apply_node, reason=reason)
-        for r in variables:
-            if r.owner is None and not isinstance(r, graph.Constant) and r not in self.inputs:
-                if isinstance(r.type, NullType):
-                    raise TypeError("Computation graph contains a NaN. " +
-                                    r.type.why_null)
-                raise MissingInputError("Undeclared input", r)
-            if not getattr(r, 'fgraph', None) is self:
-                self.__setup_r__(r)
-            self.variables.add(r)
+        if variable.owner and variable.owner not in self.apply_nodes:
+                self.__import__(variable.owner, reason=reason)
+        if (variable.owner is None and
+                not isinstance(variable, graph.Constant) and
+                variable not in self.inputs):
+            if isinstance(variable.type, NullType):
+                raise TypeError("Computation graph contains a NaN. " +
+                                variable.type.why_null)
+            raise MissingInputError("Undeclared input", variable)
+        if not getattr(variable, 'fgraph', None) is self:
+            self.__setup_r__(variable)
+        self.variables.add(variable)
 
     def __import__(self, apply_node, check=True, reason=None):
         # We import the nodes in topological order. We only are interested
@@ -445,7 +446,7 @@ class FunctionGraph(utils.object2):
         if r is new_r:
             return
 
-        self.__import_r__([new_r], reason=reason)
+        self.__import_r__(new_r, reason=reason)
         self.__add_clients__(new_r, [(node, i)])
         prune = self.__remove_clients__(r, [(node, i)], False)
         # Precondition: the substitution is semantically valid