Fix TF Longformer (#9348)

* Fix longformer

* Apply style

* Remove serving content

* Forgot a condition

* Apply style

* Address Patrick's comments

* Fix dtype

src/transformers/models/longformer/modeling_tf_longformer.py

@@ -390,7 +390,7 @@ def _compute_global_attention_mask(input_ids_shape, sep_token_indices, before_se
     True` else after `sep_token_id`.
     """
 
-    assert sep_token_indices.shape[1] == 2, "`input_ids` should have two dimensions"
+    assert shape_list(sep_token_indices)[1] == 2, "`input_ids` should have two dimensions"
     question_end_index = tf.reshape(sep_token_indices, (input_ids_shape[0], 3, 2))[:, 0, 1]
     question_end_index = tf.cast(question_end_index[:, None], tf.dtypes.int32)  # size: batch_size x 1
     # bool attention mask with True in locations of global attention
@@ -1028,7 +1028,7 @@ class TFLongformerSelfAttention(tf.keras.layers.Layer):
         )
 
         # pad to full matrix
-        padding = tf.constant(
+        padding = tf.convert_to_tensor(
             [[0, shape_list(input_tensor)[1] - window_overlap], [0, shape_list(input_tensor)[3] - window_overlap - 1]]
         )
 
@@ -1523,8 +1523,7 @@ class TFLongformerEncoder(tf.keras.layers.Layer):
         training=False,
     ):
         all_hidden_states = () if output_hidden_states else None
-        all_attentions = () if output_attentions else None
-        all_global_attentions = () if (output_attentions and is_global_attn) else None
+        all_attentions = all_global_attentions = () if output_attentions else None
 
         for i, layer_module in enumerate(self.layer):
             if output_hidden_states:
@@ -1547,7 +1546,6 @@ class TFLongformerEncoder(tf.keras.layers.Layer):
                 # bzs x seq_len x num_attn_heads x (num_global_attn + attention_window_len + 1) => bzs x num_attn_heads x seq_len x (num_global_attn + attention_window_len + 1)
                 all_attentions = all_attentions + (tf.transpose(layer_outputs[1], (0, 2, 1, 3)),)
 
-                if is_global_attn:
                 # bzs x num_attn_heads x num_global_attn x seq_len => bzs x num_attn_heads x seq_len x num_global_attn
                 all_global_attentions = all_global_attentions + (tf.transpose(layer_outputs[2], (0, 1, 3, 2)))
 
@@ -1766,7 +1764,7 @@ class TFLongformerMainLayer(tf.keras.layers.Layer):
                 )
             )
 
-            paddings = tf.constant([[0, 0], [0, padding_len]])
+        paddings = tf.convert_to_tensor([[0, 0], [0, padding_len]])
 
         if input_ids is not None:
             input_ids = tf.pad(input_ids, paddings, constant_values=pad_token_id)
@@ -1776,13 +1774,15 @@ class TFLongformerMainLayer(tf.keras.layers.Layer):
             position_ids = tf.pad(position_ids, paddings, constant_values=pad_token_id)
 
         if inputs_embeds is not None:
+
+            def pad_embeddings():
                 input_ids_padding = tf.fill((batch_size, padding_len), self.pad_token_id)
                 inputs_embeds_padding = self.embeddings(input_ids_padding)
-                inputs_embeds = tf.concat([inputs_embeds, inputs_embeds_padding], axis=-2)
+                return tf.concat([inputs_embeds, inputs_embeds_padding], axis=-2)
+
+            inputs_embeds = tf.cond(padding_len > 0, pad_embeddings, lambda: inputs_embeds)
 
-            attention_mask = tf.pad(
-                attention_mask, paddings, constant_values=False
-            )  # no attention on the padding tokens
+        attention_mask = tf.pad(attention_mask, paddings, constant_values=False)  # no attention on the padding tokens
         token_type_ids = tf.pad(token_type_ids, paddings, constant_values=0)  # pad with token_type_id = 0
 
         return (
@@ -2171,16 +2171,14 @@ class TFLongformerForQuestionAnswering(TFLongformerPreTrainedModel, TFQuestionAn
 
         # set global attention on question tokens
         if inputs["global_attention_mask"] is None and inputs["input_ids"] is not None:
-            if inputs["input_ids"] is None:
-                logger.warning(
-                    "It is not possible to automatically generate the `global_attention_mask`. Please make sure that it is correctly set."
-                )
-            elif (
-                tf.where(inputs["input_ids"] == self.config.sep_token_id).shape[0] != 3 * inputs["input_ids"].shape[0]
+            if (
+                shape_list(tf.where(inputs["input_ids"] == self.config.sep_token_id))[0]
+                != 3 * shape_list(inputs["input_ids"])[0]
             ):
                 logger.warning(
-                    f"There should be exactly three separator tokens: {self.config.sep_token_id} in every sample for questions answering. You might also consider to set `global_attention_mask` manually in the forward function to avoid this. This is most likely an error."
+                    f"There should be exactly three separator tokens: {self.config.sep_token_id} in every sample for questions answering. You might also consider to set `global_attention_mask` manually in the forward function to avoid this. This is most likely an error. The global attention is disabled for this forward pass."
                 )
+                inputs["global_attention_mask"] = tf.fill(shape_list(inputs["input_ids"]), value=0)
             else:
                 logger.info("Initializing global attention on question tokens...")
                 # put global attention on all tokens until `config.sep_token_id` is reached
@@ -2317,8 +2315,8 @@ class TFLongformerForSequenceClassification(TFLongformerPreTrainedModel, TFSeque
             inputs["global_attention_mask"] = tf.zeros_like(inputs["input_ids"])
             inputs["global_attention_mask"] = tf.tensor_scatter_nd_update(
                 inputs["global_attention_mask"],
-                [[i, 0] for i in range(inputs["input_ids"].shape[0])],
-                [1 for _ in range(inputs["input_ids"].shape[0])],
+                [[i, 0] for i in range(shape_list(inputs["input_ids"])[0])],
+                [1 for _ in range(shape_list(inputs["input_ids"])[0])],
             )
 
         outputs = self.longformer(
@@ -2443,7 +2441,7 @@ class TFLongformerForMultipleChoice(TFLongformerPreTrainedModel, TFMultipleChoic
             tf.reshape(inputs["position_ids"], (-1, seq_length)) if inputs["position_ids"] is not None else None
         )
         flat_global_attention_mask = (
-            tf.reshape(inputs["global_attention_mask"], (-1, inputs["global_attention_mask"].shape[-1]))
+            tf.reshape(inputs["global_attention_mask"], (-1, shape_list(inputs["global_attention_mask"])[-1]))
             if inputs["global_attention_mask"] is not None
             else None
         )