MakeVector.perform - optimization. modifying to skip asarray() when output space…

theano/tensor/opt.py

@@ -224,7 +224,12 @@ class MakeVector(T.Op):
     def __str__(self):
         return self.__class__.__name__
     def perform(self, node, inputs, (out,)):
+        # not calling theano._asarray as optimization
+        if out[0] is None:
             out[0] = theano._asarray(inputs, dtype=node.outputs[0].dtype)
+        else:
+            # assume that out has correct dtype.  there is no cheap way to check
+            out[0][...] = inputs
 
 make_vector = MakeVector()