Merge pull request #8344 from peakji:patch-1

PiperOrigin-RevId: 304206315

official/nlp/modeling/layers/position_embedding.py

@@ -111,15 +111,10 @@ class PositionEmbedding(tf.keras.layers.Layer):
 
   def call(self, inputs):
     """Implements call() for the layer."""
-    if self._use_dynamic_slicing:
     input_shape = tf_utils.get_shape_list(inputs, expected_rank=3)
-      seq_length = input_shape[1]
-      width = input_shape[2]
-
-      position_embeddings = tf.expand_dims(
-          tf.slice(self._position_embeddings, [0, 0], [seq_length, width]),
-          axis=0)
+    if self._use_dynamic_slicing:
+      position_embeddings = self._position_embeddings[:input_shape[1], :]
     else:
-      position_embeddings = tf.expand_dims(self._position_embeddings, axis=0)
+      position_embeddings = self._position_embeddings
 
-    return position_embeddings
+    return tf.broadcast_to(position_embeddings, input_shape)

official/nlp/modeling/layers/position_embedding_test.py

@@ -40,7 +40,7 @@ class PositionEmbeddingLayerTest(keras_parameterized.TestCase):
 
     # When using static positional embedding shapes, the output is expected
     # to be the same as the input shape in all dimensions save batch.
-    expected_output_shape = [1, sequence_length, width]
+    expected_output_shape = [None, sequence_length, width]
     self.assertEqual(expected_output_shape, output_tensor.shape.as_list())
     # The default output dtype for this layer should be tf.float32.
     self.assertEqual(tf.float32, output_tensor.dtype)
@@ -55,7 +55,7 @@ class PositionEmbeddingLayerTest(keras_parameterized.TestCase):
 
     # When using static positional embedding shapes, the output is expected
     # to be the same as the input shape in all dimensions save batch.
-    expected_output_shape = [1, sequence_length, width]
+    expected_output_shape = [None, sequence_length, width]
     self.assertEqual(expected_output_shape, output_tensor.shape.as_list())
     # The default output dtype for this layer should be tf.float32.
     self.assertEqual(tf.float16, output_tensor.dtype)
@@ -72,7 +72,7 @@ class PositionEmbeddingLayerTest(keras_parameterized.TestCase):
     # When using dynamic positional embedding shapes, the output is expected
     # to be the same as the input shape in all dimensions - but may be None if
     # the input shape is None there.
-    expected_output_shape = [1, None, width]
+    expected_output_shape = [None, None, width]
     self.assertEqual(expected_output_shape, output_tensor.shape.as_list())
 
   def test_dynamic_layer_slicing(self):