Fix runtime crash with the local_subtensor_of_alloc optimization when the input…

NEWS.txt

@@ -168,6 +168,7 @@ Crashes fixed:
  * Support for OSX Enthought Python Distribution 7.x. (Graham Taylor, Olivier)
  * When the subtensor inputs had 0 dimensions and the outputs 0 dimensions. (Frederic)
  * Crash when the step to subtensor was not 1 in conjunction with some optimization. (Frederic, reported by Olivier Chapelle)
+ * Runtime crash related to an optimization with subtensor of alloc (reported by Razvan, fixed by Frederic)
  * Fix dot22scalar cast of integer scalars (Justin Bayer, Frédéric, Olivier)
  * Fix runtime crash in gemm, dot22. FB
  * Fix on 32bits computer: make sure all shape are int64.(Olivier)

theano/tensor/opt.py

@@ -1842,6 +1842,12 @@ def local_subtensor_of_alloc(node):
         # If val was not copied over that dim,
         # we need to take the appropriate subtensor on it.
         if i >= n_added_dims:
+            # We check that the corresponding val dimensions was
+            # not a broadcasted dimensions.
+            if (val.type.ndim > (i - n_added_dims) and
+                val.type.broadcastable[i - n_added_dims]):
+                val_slices.append(slice(None))
+            else:
                 val_slices.append(sl)
 
         csl, _ = T.get_canonical_form_slice(sl, dim)

theano/tensor/tests/test_opt.py

@@ -2073,7 +2073,15 @@ class Test_alloc_zero(unittest.TestCase):
 
 def test_local_subtensor_of_alloc():
     x = tensor.matrix('x')
-    y = tensor.vector('y')
+
+    # DebugMode should detect if something goes wrong.
+    # test shape combination of odd and event shape.
+    for shape in [(3, 5), (4, 6), (3, 8), (4, 7)]:
+
+        xval = numpy.zeros(shape, dtype=config.floatX)
+        yval = numpy.arange(shape[1], dtype=config.floatX)
+
+        for y in [theano.shared(yval), tensor.constant([1.])]:
 
             # The rows of yx are copies of y
             yx = tensor.alloc(y, x.shape[0], x.shape[1])
@@ -2086,13 +2094,6 @@ def test_local_subtensor_of_alloc():
             z_vec = yx[:, 3]
             assert z_vec.ndim == 1
 
-    # DebugMode should detect if something goes wrong.
-    # test shape combination of odd and event shape.
-    for shape in [(3, 5), (4, 6), (3, 8), (4, 7)]:
-
-        xval = numpy.zeros(shape, dtype=config.floatX)
-        yval = numpy.arange(shape[1], dtype=config.floatX)
-
             for slices in [
                 # results are vector
                 (slice(None), 3),
@@ -2106,8 +2107,8 @@ def test_local_subtensor_of_alloc():
                 (slice(1, None, 2)),
                 ]:
                 z = yx.__getitem__(slices)
-            f = theano.function([x, y], z)
-            val = f(xval, yval)
+                f = theano.function([x], z)
+                val = f(xval)
                 assert xval.__getitem__(slices).shape == val.shape