Fixed cycles in graph and added back the condition checking empty shape

theano/gof/opt.py

@@ -1256,7 +1256,6 @@ class LocalOptGroup(LocalOptimizer):
             for c in o.tracks():
                 self.track_map.setdefault(c, []).append(o)
 
-
     def __str__(self):
         return getattr(self, '__name__',
                        ('LocalOptGroup(%s)' %
@@ -1273,6 +1272,7 @@ class LocalOptGroup(LocalOptimizer):
     def transform(self, node):
         if len(self.opts) == 0:
             return
+
         def apply_mult_opts(opt_list, node, multiple_opts=False):
             repl = False
             for opt in opt_list:

theano/gof/optdb.py

@@ -413,8 +413,10 @@ class LocalGroupDB(DB):
         ret = opt.LocalOptGroup(*opts, apply_all_opts=self.apply_all_opts)
         return ret
 
+
 class TopoDB(DB):
     """
+
     Generate a local optimizer of type LocalOptGroup instead
     of a global optimizer.
 

theano/tensor/basic.py

@@ -2354,6 +2354,8 @@ def zeros(shape, dtype=None):
         shape = [shape]
     if dtype is None:
         dtype = config.floatX
+    if isinstance(shape, (list, tuple)) and len(shape) == 0:
+        return constant(0.0, dtype=dtype)
     return alloc(numpy.array(0, dtype=dtype), *shape)
 
 
@@ -2365,6 +2367,8 @@ def ones(shape, dtype=None):
         shape = [shape]
     if dtype is None:
         dtype = config.floatX
+    if isinstance(shape, (list, tuple)) and len(shape) == 0:
+        return constant(1.0, dtype=dtype)
     return alloc(numpy.array(1, dtype=dtype), *shape)
 
 

theano/tensor/opt.py

@@ -22,7 +22,7 @@ from theano import gof
 from theano.compat import izip
 from theano.gof import opt, InconsistencyError, TopoOptimizer, graph
 from theano.gof import Variable, Constant
-from theano.gof.opt import copy_stack_trace, in2out, out2in, LocalOptGroup
+from theano.gof.opt import copy_stack_trace, in2out
 from theano.gof.utils import MethodNotDefined
 from theano.gradient import DisconnectedType
 from theano.configparser import config
@@ -56,6 +56,7 @@ _logger = logging.getLogger('theano.tensor.opt')
 
 # Utilities
 
+
 def _fill_chain(new_out, orig_inputs):
     for i in orig_inputs:
         new_out = T.fill(i, new_out)
@@ -1901,7 +1902,7 @@ def local_subtensor_remove_broadcastable_index(node):
 
 @register_specialize
 @register_canonicalize('fast_compile_gpu')
-#@register_useless
+# @register_useless
 @gof.local_optimizer([Subtensor, AdvancedSubtensor1])
 def local_subtensor_make_vector(node):
     """
@@ -2035,7 +2036,7 @@ def local_useless_elemwise(node):
             return [node.inputs[0]]
         elif (node.op.scalar_op == theano.scalar.identity and
               len(node.inputs) == 1):
-            return [node.inputs[0]]
+            return
 
         elif (isinstance(node.op.scalar_op, scalar.AND) and
               len(node.inputs) == 2):