Merge pull request #472 from lamblin/fix_local_upcast_elemwise_constant_inputs

NEWS.txt

@@ -9,6 +9,9 @@ Bug fixes (the result changed):
 
 Crashes fixes:
  * More cases supported in AdvancedIncSubtensor1. (Olivier D.)
+ * Fix crash when a broadcasted constant was used as input of an
+   elemwise Op and needed to be upcasted to match the op's output.
+   (Reported by John Salvatier, fixed by Pascal L.)
 
 Interface change:
  * The Theano flag "nvcc.flags" is now included in the hard part of the key.

theano/tensor/opt.py

@@ -1443,7 +1443,9 @@ def local_upcast_elemwise_constant_inputs(node):
                         # works only for scalars
                         cval_i = get_constant_value(i)
                         if all(i.broadcastable):
-                            new_inputs.append(T.cast(cval_i, output_dtype))
+                            new_inputs.append(T.shape_padleft(
+                                T.cast(cval_i, output_dtype),
+                                i.ndim))
                         else:
                             if shape_i is None:
                                 return

theano/tensor/tests/test_opt.py

@@ -3532,6 +3532,12 @@ class Test_lift_transpose_through_dot(unittest.TestCase):
         assert str(g) == sg
 
 
+def test_local_upcast_elemwise_constant_inputs():
+    s = dvector("s")
+    x = tensor.sum(tensor.log(10**s))
+    f = function([s], [tensor.grad(x, s)])
+    f([-42, -2.1, -1, -0.5, 0, 0.2, 1, 2, 12])
+
 if __name__ == '__main__':
 #    unittest.main()
     test_fusion().tes_memory_leak()