Simplify roll graph in case of 1-d input.

In the case of a default axis argument and a 1-d tensor, don't create flatten and reshape nodes that need to be optimized out when it's simple enough not to do so.

Simplify roll graph in case of 1-d input.
5b5d1d9f · David Warde-Farley · 5b3b5418 · 5b5d1d9f
--- a/theano/tensor/basic.py
+++ b/theano/tensor/basic.py
@@ -4313,8 +4313,11 @@ def roll(x, shift, axis=None):
        Output tensor, with the same shape as `x`.
    """
    if axis is None:
+        if x.ndim > 1:
            y = x.flatten()
            return roll(y, shift, axis=0).reshape(x.shape)
+        else:
+            axis = 0

    # A slice of all elements in a dimension ':'
    allslice = slice(None)