pre-clean up some fill inside opt.

theano/tensor/opt.py

@@ -2004,20 +2004,22 @@ def local_useless_elemwise(node):
     if isinstance(node.op, T.Elemwise):
         def zeros_like(node, in_idx):
             # it is the same var in the graph. That will always be true
-            return [T.fill(node.inputs[in_idx],
-                           T.constant(0.0, dtype=node.outputs[0].type.dtype))]
+            ret = T.fill(node.inputs[in_idx],
+                         T.constant(0.0, dtype=node.outputs[0].type.dtype))
+            ret = pre_greedy_local_optimizer(local_useless_fill, ret)
+            return [ret]
 
         def ones_like(node, in_idx):
             # it is the same var in the graph. That will always be true
-            return [T.fill(node.inputs[in_idx],
-                           T.constant(1.0, dtype=node.outputs[0].type.dtype))]
+            ret = T.fill(node.inputs[in_idx],
+                         T.constant(1.0, dtype=node.outputs[0].type.dtype))
+            ret = pre_greedy_local_optimizer(local_useless_fill, ret)
+            return [ret]
 
         if node.op.scalar_op == theano.scalar.eq and len(node.inputs) == 2:
             if node.inputs[0] == node.inputs[1]:
                 # it is the same var in the graph. That will always be true
-                ret = [T.fill(node.inputs[0],
-                              T.constant(1.0,
-                                         dtype=node.outputs[0].type.dtype))]
+                ret = ones_like(node, 0)
 
                 # Copy stack trace from input to constant output
                 copy_stack_trace(node.outputs[0], ret)
@@ -2025,9 +2027,7 @@ def local_useless_elemwise(node):
         elif node.op.scalar_op == theano.scalar.neq and len(node.inputs) == 2:
             if node.inputs[0] == node.inputs[1]:
                 # it is the same var in the graph. That will always be false
-                ret = [T.fill(node.inputs[0],
-                              T.constant(0.0,
-                                         dtype=node.outputs[0].type.dtype))]
+                ret = zeros_like(node, 0)
 
                 # Copy stack trace from input to constant output
                 copy_stack_trace(node.outputs[0], ret)