Only resize embeddings when necessary (#20043)

* Only resize embeddings when necessary

* Add comment

examples/pytorch/multiple-choice/run_swag_no_trainer.py

@@ -398,7 +398,11 @@ def main():
         logger.info("Training new model from scratch")
         model = AutoModelForMultipleChoice.from_config(config)
 
-    model.resize_token_embeddings(len(tokenizer))
+    # We resize the embeddings only when necessary to avoid index errors. If you are creating a model from scratch
+    # on a small vocab and want a smaller embedding size, remove this test.
+    embedding_size = model.get_input_embeddings().weight.shape[0]
+    if len(tokenizer) > embedding_size:
+        model.resize_token_embeddings(len(tokenizer))
 
     # Preprocessing the datasets.
     # First we tokenize all the texts.