Merge pull request #2539 from carriepl/activate_scan_no_output_from_inplace_optimization

theano/scan_module/scan_op.py

@@ -118,6 +118,14 @@ class Scan(PureOp):
                 optimizer=mode_instance.provided_optimizer,
                 linker=mode_instance.linker.clone(allow_gc=self.allow_gc))
 
+        # Now that scan has its mode instance, we activate optimization
+        # add_no_output_from_inplace in this mode instance. This will prevent
+        # Scan from producing outputs by means of inplace operations and
+        # therefore allow it to pre-allocate memory storage for the outputs,
+        # avoiding needless copies.
+        self.mode_instance = self.mode_instance.including(
+                                                "add_no_output_from_inplace")
+
         if not hasattr(self, 'name') or self.name is None:
             self.name = 'scan_fn'
         # to have a fair __eq__ comparison later on, we update the info with

theano/scan_module/tests/test_scan.py

@@ -1928,7 +1928,6 @@ class T_Scan(unittest.TestCase):
         s_v = s_v[:-1]
         for i in xrange(100):
             cost = learn_rnn_fn(s_v, t_v)
-            print i, cost
         pred = eval_rnn_fn(s_v)
         assert cost < 0.02