update label prepare to speedup

pretrain_llama.py

@@ -123,9 +123,7 @@ for data_step in range(num_training_steps):
         batch = next(train_loader_iter)
         for k, v in batch.items():
             batch[k] = v.to(accelerator.device)
-        labels = batch["input_ids"].clone()
-        labels[labels == tokenizer.pad_id] = -100
-        out = model(**batch, labels=labels)
+        out = model(**batch, labels=batch['input_ids'])
         total_loss = out.loss
         losses = {"total_loss": total_loss}
         accelerator.backward(total_loss)