ariG23498/layer-skip-v1

class LayerSkipSFTTrainer(SFTTrainer):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.early_exit_layer = 0 # initialize with 0
        self.always_last_layer = True

    def compute_loss(self, model, inputs, return_outputs=False, num_items_in_batch=None):
        self.early_exit_layer = (self.early_exit_layer % (model.config.num_hidden_layers - 1)) + 1 # rotates between [1, num_hidden_layers-1]

        labels = inputs.pop("labels")
        outputs = model(**inputs, output_hidden_states=True)
        
        hidden_state = outputs["hidden_states"][self.early_exit_layer]
        logits = model.lm_head(hidden_state)
        loss = model.loss_function(logits=logits, labels=labels, vocab_size=model.vocab_size)
        
        if self.always_last_layer:
            loss = loss + model.loss_function(logits=outputs["logits"], labels=labels, vocab_size=model.vocab_size)
                
        return loss