fix simple_rnn_cell, gru_cell and lstm_cell zero_div_error

Author: joey12300

python/paddle/fluid/tests/unittests/rnn/test_rnn_cells.py

@@ -60,9 +60,16 @@ def test_with_zero_state(self):
         y2, h2 = rnn2(paddle.to_tensor(x))
         np.testing.assert_allclose(h1, h2.numpy(), atol=1e-8, rtol=1e-5)
 
+    def test_errors(self):
+        def test_zero_hidden_size():
+            cell = paddle.nn.SimpleRNNCell(-1, 0)
+
+        self.assertRaises(ValueError, test_zero_hidden_size)
+
     def runTest(self):
         self.test_with_initial_state()
         self.test_with_zero_state()
+        self.test_errors()
 
 
 class TestGRUCell(unittest.TestCase):
@@ -103,9 +110,16 @@ def test_with_zero_state(self):
         y2, h2 = rnn2(paddle.to_tensor(x))
         np.testing.assert_allclose(h1, h2.numpy(), atol=1e-8, rtol=1e-5)
 
+    def test_errors(self):
+        def test_zero_hidden_size():
+            cell = paddle.nn.GRUCell(-1, 0)
+
+        self.assertRaises(ValueError, test_zero_hidden_size)
+
     def runTest(self):
         self.test_with_initial_state()
         self.test_with_zero_state()
+        self.test_errors()
 
 
 class TestLSTMCell(unittest.TestCase):
@@ -150,9 +164,16 @@ def test_with_zero_state(self):
         np.testing.assert_allclose(h1, h2.numpy(), atol=1e-8, rtol=1e-5)
         np.testing.assert_allclose(c1, c2.numpy(), atol=1e-8, rtol=1e-5)
 
+    def test_errors(self):
+        def test_zero_hidden_size():
+            cell = paddle.nn.LSTMCell(-1, 0)
+
+        self.assertRaises(ValueError, test_zero_hidden_size)
+
     def runTest(self):
         self.test_with_initial_state()
         self.test_with_zero_state()
+        self.test_errors()
 
 
 def load_tests(loader, tests, pattern):

python/paddle/nn/layer/rnn.py

@@ -332,6 +332,10 @@ def __init__(self,
                  bias_hh_attr=None,
                  name=None):
         super(SimpleRNNCell, self).__init__()
+        if hidden_size <= 0:
+            raise ValueError(
+                "hidden_size of {} must be greater than 0, but now equals to {}".
+                format(self.__class__.__name__, hidden_size))
         std = 1.0 / math.sqrt(hidden_size)
         self.weight_ih = self.create_parameter(
             (hidden_size, input_size),
@@ -480,6 +484,10 @@ def __init__(self,
                  bias_hh_attr=None,
                  name=None):
         super(LSTMCell, self).__init__()
+        if hidden_size <= 0:
+            raise ValueError(
+                "hidden_size of {} must be greater than 0, but now equals to {}".
+                format(self.__class__.__name__, hidden_size))
         std = 1.0 / math.sqrt(hidden_size)
         self.weight_ih = self.create_parameter(
             (4 * hidden_size, input_size),
@@ -627,6 +635,10 @@ def __init__(self,
                  bias_hh_attr=None,
                  name=None):
         super(GRUCell, self).__init__()
+        if hidden_size <= 0:
+            raise ValueError(
+                "hidden_size of {} must be greater than 0, but now equals to {}".
+                format(self.__class__.__name__, hidden_size))
         std = 1.0 / math.sqrt(hidden_size)
         self.weight_ih = self.create_parameter(
             (3 * hidden_size, input_size),