Following code review optimized Rebroadcast infer_shape.

theano/tensor/basic.py

@@ -3292,7 +3292,16 @@ class Rebroadcast(Op):
         # restore the broadcasting pattern of the input
         return Rebroadcast(*[(axis, x.type.broadcastable[axis]) for axis, value in self.axis.iteritems()])(gz),
     def infer_shape(self, node, ishapes):
-        return ishapes
+        assert len(ishapes)==1
+        l = []
+        one = constant(1)
+        for ax in range(len(ishapes[0])):
+            if self.axis.get(ax, False):
+                l.append(one)
+            else:
+                l.append(ishapes[0][ax])
+
+        return [tuple(l)]
 
 def addbroadcast(x, *axes):
     """

theano/tensor/tests/test_basic.py

@@ -4173,9 +4173,19 @@ class test_broadcast(unittest.TestCase):
 
     def test_infer_shape(self):
         x = matrix()
-        y = addbroadcast(x,0)
+        y = addbroadcast(x, 0)
         f = theano.function([x], y.shape)
-        f(numpy.zeros((1,5), dtype=config.floatX))
+        assert (f(numpy.zeros((1,5), dtype=config.floatX)) == [1,5]).all()
+        topo = f.maker.env.toposort()
+        if theano.config.mode != 'FAST_COMPILE':
+            assert len(topo) == 2
+            assert isinstance(topo[0].op, opt.Shape_i)
+            assert isinstance(topo[1].op, opt.MakeVector)
+
+        x = matrix()
+        y = unbroadcast(x, 0)
+        f = theano.function([x], y.shape)
+        assert (f(numpy.zeros((2,5), dtype=config.floatX)) == [2,5]).all()
         topo = f.maker.env.toposort()
         if theano.config.mode != 'FAST_COMPILE':
             assert len(topo) == 3
@@ -4183,6 +4193,18 @@ class test_broadcast(unittest.TestCase):
             assert isinstance(topo[1].op, opt.Shape_i)
             assert isinstance(topo[2].op, opt.MakeVector)
 
+        x = row()
+        y = unbroadcast(x, 0)
+        f = theano.function([x], y.shape)
+        assert (f(numpy.zeros((1,5), dtype=config.floatX)) == [1,5]).all()
+        topo = f.maker.env.toposort()
+        if theano.config.mode != 'FAST_COMPILE':
+            assert len(topo) == 2
+            assert isinstance(topo[0].op, opt.Shape_i)
+            assert isinstance(topo[1].op, opt.MakeVector)
+
+
+
 def test_mod():
     """
     We add this test as not all language and C implementation give the same