use safe_to_cpu to transfer output results in op_lifter, since some ops return…

theano/sandbox/gpuarray/opt.py

@@ -55,6 +55,20 @@ def register_opt(*tags, **kwargs):
 register_opt()(theano.tensor.opt.local_track_shape_i)
 
 
+def safe_to_gpu(x):
+    if isinstance(x.type, tensor.TensorType):
+        return gpu_from_host(x)
+    else:
+        return x
+
+
+def safe_to_cpu(x):
+    if isinstance(x.type, GpuArrayType):
+        return host_from_gpu(x)
+    else:
+        return x
+
+
 def op_lifter(OP):
     """
     OP(..., host_from_gpu(), ...) -> host_from_gpu(GpuOP(...))
@@ -74,10 +88,10 @@ def op_lifter(OP):
                     # This is needed as sometimes new_op inherit from OP.
                     if new_op and new_op != node.op:
                         if isinstance(new_op, theano.Op):
-                            return [host_from_gpu(o) for o in
+                            return [safe_to_cpu(o) for o in
                                     new_op(*node.inputs, return_list=True)]
                         elif isinstance(new_op, (tuple, list)):
-                            return [host_from_gpu(o) for o in new_op]
+                            return [safe_to_cpu(o) for o in new_op]
                         else:  # suppose it is a variable on the GPU
                             return [host_from_gpu(new_op)]
             return False
@@ -463,20 +477,6 @@ def tensor_to_gpu(x):
         return x
 
 
-def safe_to_gpu(x):
-    if isinstance(x.type, tensor.TensorType):
-        return gpu_from_host(x)
-    else:
-        return x
-
-
-def safe_to_cpu(x):
-    if isinstance(x.type, GpuArrayType):
-        return host_from_gpu(x)
-    else:
-        return x
-
-
 def gpu_safe_new(x, tag=''):
     """
     Internal function that constructs a new variable from x with the same