[T5] Fix init in TF and Flax for pretraining (huggingface#17294)

* fix init

* Apply suggestions from code review

* fix

* finish

* Update src/transformers/modeling_tf_utils.py

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

src/transformers/models/t5/modeling_t5.py

@@ -768,6 +768,8 @@ def _init_weights(self, module):
             # Mesh TensorFlow embeddings initialization
             # See https://github.com/tensorflow/mesh/blob/fa19d69eafc9a482aff0b59ddd96b025c0cb207d/mesh_tensorflow/layers.py#L1624
             module.shared.weight.data.normal_(mean=0.0, std=factor * 1.0)
+            if hasattr(module, "lm_head") and not self.config.tie_word_embeddings:
+                module.lm_head.weight.data.normal_(mean=0.0, std=factor * 1.0)
         elif isinstance(module, T5DenseReluDense):
             # Mesh TensorFlow FF initialization
             # See https://github.com/tensorflow/mesh/blob/master/mesh_tensorflow/transformer/transformer_layers.py#L56

src/transformers/models/t5/modeling_tf_t5.py

@@ -1112,7 +1112,9 @@ def _shift_right(self, input_ids):
 class TFT5Model(TFT5PreTrainedModel):
     def __init__(self, config, *inputs, **kwargs):
         super().__init__(config, *inputs, **kwargs)
-        self.shared = TFSharedEmbeddings(config.vocab_size, config.d_model, name="shared")
+        self.shared = TFSharedEmbeddings(
+            config.vocab_size, config.d_model, name="shared", initializer_range=self.config.initializer_factor
+        )
 
         # retrieve correct absolute scope for embed token wrapper
         with tf.compat.v1.variable_scope("shared") as shared_abs_scope_name:
@@ -1259,8 +1261,9 @@ class TFT5ForConditionalGeneration(TFT5PreTrainedModel, TFCausalLanguageModeling
     def __init__(self, config, *inputs, **kwargs):
         super().__init__(config, *inputs, **kwargs)
         self.model_dim = config.d_model
-
-        self.shared = TFSharedEmbeddings(config.vocab_size, config.d_model, name="shared")
+        self.shared = TFSharedEmbeddings(
+            config.vocab_size, config.d_model, name="shared", initializer_range=self.config.initializer_factor
+        )
 
         # retrieve correct absolute scope for embed token wrapper
         with tf.compat.v1.variable_scope("shared") as shared_abs_scope_name:
@@ -1600,7 +1603,9 @@ def _reorder_cache(self, past, beam_idx):
 class TFT5EncoderModel(TFT5PreTrainedModel):
     def __init__(self, config, *inputs, **kwargs):
         super().__init__(config, *inputs, **kwargs)
-        self.shared = TFSharedEmbeddings(config.vocab_size, config.d_model, name="shared")
+        self.shared = TFSharedEmbeddings(
+            config.vocab_size, config.d_model, name="shared", initializer_range=self.config.initializer_factor
+        )
 
         # retrieve correct absolute scope for embed token wrapper
         with tf.compat.v1.variable_scope("shared") as shared_abs_scope_name: