!205 add ReverseSequenceGrad

Merge pull request !205 from xutianchun/reverse_sequence_grad

mindspore/ops/_grad/grad_array_ops.py

@@ -580,3 +580,14 @@ def get_bprop_batch_to_space_nd(self):
         dx = batch_to_space_nd_grad(dout)
         return (dx,)
     return bprop
+
+
+@bprop_getters.register(P.ReverseSequence)
+def get_bprop_reverse_sequence(self):
+    """Generate bprop for ReverseSequence"""
+    reverse_sequence_grad = P.ReverseSequence(batch_dim=self.batch_dim_, seq_dim=self.seq_dim_)
+
+    def bprop(x, seq_lengths, out, dout):
+        dx = reverse_sequence_grad(dout, seq_lengths)
+        return dx, zeros_like(seq_lengths)
+    return bprop

tests/ut/python/ops/test_ops.py

@@ -1378,6 +1378,11 @@ test_case_array_ops = [
         'desc_inputs': [Tensor(np.array([[1, 2, 3], [4, 5, 6], [4, 2, 1]]).astype(np.float32)),
                         Tensor(np.array([0, 1, 1]).astype(np.int32))],
         'desc_bprop': [Tensor(np.array([[1, 2, 3], [4, 2, 1]]).astype(np.float32))]}),
+    ('ReverseSequence', {
+        'block': P.ReverseSequence(1, 0),
+        'desc_inputs': [Tensor(np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]]).astype(np.float32)),
+                        Tensor(np.array([1, 2, 3]).astype(np.int32))],
+        'desc_bprop': [[3, 3]]}),
 ]
 
 test_case_other_ops = [