Add test for the fix

theano/sandbox/cuda/tests/test_nnet.py

@@ -435,3 +435,22 @@ class test_SoftMax(unittest.TestCase):
                         i.op,
                         theano.tensor.nnet.SoftmaxGrad
                     )]) == 1)
+
+        # Verify that the SoftmaxGrad -> GpuDnnSoftmaxGrad do not
+        # crash with manual graph
+        y = T.vector('y')
+        o = theano.tensor.nnet.SoftmaxGrad()(y, y*2)
+        f = theano.function([y], o, mode=mode_with_gpu)
+        sorted_f = f.maker.fgraph.toposort()
+        assert(len([i
+                    for i in sorted_f
+                    if isinstance(
+                        i.op,
+                        theano.sandbox.cuda.dnn.GpuDnnSoftmaxGrad
+                    )]) == 0)
+        assert(len([i
+                    for i in sorted_f
+                    if isinstance(
+                        i.op,
+                        theano.tensor.nnet.SoftmaxGrad
+                    )]) == 1)