Merge pull request #3221 from carriepl/scan_opt_bug

theano/configparser.py

@@ -116,6 +116,10 @@ def change_flags(**kwargs):
                          if v.fullname == k]
                     assert len(l) == 1
                     l[0].__set__(None, old_val[k])
+
+        # Make sure that the name of the decorated function remains the same.
+        inner.__name__ = f.__name__
+
         return inner
     return change_flags_exec
 

theano/scan_module/scan_opt.py

@@ -472,13 +472,12 @@ class PushOutSeqScan(gof.Optimizer):
 
         for nd in local_fgraph_topo:
             if (nd not in to_remove_set and
-               all([(x in inner_non_seqs_set) or
-               (x.owner in to_remove_set) or
-               isinstance(x, tensor.Constant) or
-               (x in inner_seqs_set) for x in nd.inputs]) and
-               isinstance(nd.op, theano.tensor.Elemwise)):
+                all([(x in inner_non_seqs_set) or
+                     (x.owner in to_remove_set) or
+                     isinstance(x, tensor.Constant) or
+                     (x in inner_seqs_set) for x in nd.inputs]) and
+                isinstance(nd.op, theano.tensor.Elemwise)):
 
-                to_remove_set.add(nd)
                 outside_ins = []
                 depends_on_seqs = False
 
@@ -511,6 +510,8 @@ class PushOutSeqScan(gof.Optimizer):
                     # scan.
                     continue
 
+                to_remove_set.add(nd)
+
                 # Do not call make_node for test_value
                 nw_outer_node = nd.op(*outside_ins,
                                       **dict(return_list=True))[0].owner

theano/scan_module/tests/test_scan.py

@@ -2696,6 +2696,23 @@ class T_Scan(unittest.TestCase):
         utt.assert_allclose(expected_output, scan_output)
         utt.assert_allclose(expected_output, jacobian_outputs)
 
+    @theano.configparser.change_flags(on_opt_error='raise')
+    def test_pushout_seqs2(self):
+        # This test for a bug with PushOutSeqScan that was reported on the
+        # theano-user mailing list where the optimization raised an exception
+        # when applied on this graph.
+        x = tensor.matrix()
+        outputs, updates = theano.scan(
+            lambda x: [x*x, tensor.constant(0).copy().copy()],
+            n_steps=2,
+            sequences=[],
+            non_sequences=[],
+            outputs_info=[x, None])
+
+        # Compile a theano function where any optimization error will lead to
+        # an exception being raised
+        theano.function([x], outputs, updates=updates)
+
     def test_sequence_dict(self):
         # Test that we can specify sequences as a dictionary with
         # only the 'input' key