Add cuDNN conv test to reproduce a problem related to

theano/gpuarray/tests/test_dnn.py

@@ -2666,3 +2666,31 @@ class TestDnnConv3DRuntimeAlgorithms(TestDnnConv2DRuntimeAlgorithms):
         (1, [(4, 2, 20, 20, 20), (2, 2, 20, 19, 18)]),  # cache should be used
         (1, [(1, 2, 3, 4, 5), (6, 2, 3, 2, 1)])
     ]
+
+
+def test_conv_guess_once_with_dtypes():
+    utt.seed_rng()
+    inputs_shape = (2, 3, 5, 5)
+    filters_shape = (2, 3, 40, 4)
+    border_mode = 'full'
+
+    def get_function(dtype, precision):
+        inputs_val = np.random.random(inputs_shape).astype(dtype)
+        filters_val = np.random.random(filters_shape).astype(dtype)
+        inputs_val /= 10
+        filters_val /= 10
+        inputs = theano.shared(inputs_val)
+        filters = theano.shared(filters_val)
+        conv = dnn.dnn_conv(img=inputs, kerns=filters, border_mode=border_mode, precision=precision,
+                            algo='guess_once', direction_hint='forward!')
+        return theano.function([], conv)
+
+    f_true_half_config = get_function('float16', 'float16')
+    f_pseudo_half_config = get_function('float16', 'float32')
+    f_float_config = get_function('float32', 'float32')
+    f_double_config = get_function('float64', 'float64')
+    # Let's just see if everything runs without raising any exception.
+    f_true_half_config()
+    f_pseudo_half_config()
+    f_float_config()
+    f_double_config()