Make scan opt before blas opt.

theano/scan_module/scan_opt.py

@@ -129,7 +129,9 @@ def remove_constants_and_unused_inputs_scan(node):
         return False
 
 scan_seqopt = theano.gof.SequenceDB()
-optdb.register('scan_seqopt', scan_seqopt, 1.9, 'fast_run', 'scan')
+# We run before blas opt at 1.7 and specialize 2.0
+# but after stabilize at 1.5. Should we put it before stabilize?
+optdb.register('scan_seqopt', scan_seqopt, 1.6, 'fast_run', 'scan')
 scan_seqopt.register('scanOp_remove_constants_and_unused_inputs',
                      opt.in2out(remove_constants_and_unused_inputs_scan,
                                 ignore_newtrees=True),

theano/scan_module/tests/test_scan.py

@@ -2599,6 +2599,31 @@ class T_Scan(unittest.TestCase):
         assert numpy.allclose(theano_x , v_x[-2:])
         assert numpy.allclose(theano_y , v_y[-4:])
 
+    def test_opt_order(self):
+        """  Verify that scan optimizations are applied before blas
+           optimizations.
+           This is needed as otherwise, the dot won't become a dot22
+           so it will be slower and won't get transferred to the gpu.
+        """
+        x = theano.tensor.matrix('x')
+        A = theano.tensor.matrix('A')
+
+        z, updates = theano.scan(
+            theano.dot,
+            sequences=[],
+            non_sequences=[x, A],
+            n_steps=2)
+        f = theano.function([x, A], z)
+        topo = f.maker.env.toposort()
+        if theano.config.mode != "FAST_COMPILE":
+            assert any([isinstance(node.op, tensor.blas.Dot22)
+                        for node in topo])
+
+        vx = numpy.array([[1., 1.], [2., 2.]], dtype=theano.config.floatX)
+        vA = numpy.array([[1., 1.], [1., 0.]], dtype=theano.config.floatX)
+        vR = numpy.array([[[2, 1], [4, 2]], [[2, 1], [4, 2]]],
+                         dtype=theano.config.floatX)
+        assert numpy.allclose(f(vx, vA), vR)
 
 
 def test_speed():