minor changes

theano/gpuarray/opt.py

@@ -11,8 +11,7 @@ from theano.compile import optdb
 from theano.compile.ops import shape_i
 from theano.gof import (local_optimizer, EquilibriumDB, TopoOptimizer,
                         SequenceDB, Optimizer, toolbox)
-from theano.gof.optdb import LocalGroupDB, Query
-from theano.gof.op import Op
+from theano.gof.optdb import LocalGroupDB
 from theano.ifelse import IfElse
 
 from theano.scalar.basic import Scalar, Pow, Cast
@@ -218,7 +217,7 @@ gpu_seqopt.register('InputToGpuArrayOptimizer', InputToGpuOptimizer(),
 
 class GraphToGPU(Optimizer):
     """
-    Transfer the graph as a whole to GPU instead of replacing nodes
+    Transfer the graph as a whole to GPU instead of transfering node by node.
     """
     def add_requirements(self, fgraph):
         fgraph.attach_feature(toolbox.ReplaceValidate())
@@ -279,13 +278,15 @@ class GraphToGPU(Optimizer):
                 for o in node.outputs:
                     mapping[o] = o
 
+        new_nodes = []
         for o in fgraph.outputs:
             new_o = mapping[o]
             if new_o.type != o.type:
                 assert isinstance(o.type, tensor.TensorType)
                 assert isinstance(new_o.type, GpuArrayType)
                 new_o = host_from_gpu(new_o)
-            fgraph.replace_validate(o, new_o)
+            new_nodes.append(new_o)
+        fgraph.replace_all_validate(zip(fgraph.outputs, new_nodes))
 
 
 gpu_seqopt.register('GraphToGPU', GraphToGPU(),