""" PyTorch GPTNeoX model.""" from typing import Optional, Tuple, Union import torch import torch.utils.checkpoint from torch import nn from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss, MSELoss from transformers.activations import ACT2FN from transformers.modeling_outputs import ( BaseModelOutputWithPast, CausalLMOutputWithPast, QuestionAnsweringModelOutput, SequenceClassifierOutputWithPast, TokenClassifierOutput, ) from transformers.modeling_utils import PreTrainedModel from transformers.utils import logging from transformers.models.gpt_neox.configuration_gpt_neox import GPTNeoXConfig from transformers.models.gpt_neox.modeling_gpt_neox import GPTNeoXPreTrainedModel, GPTNeoXMLP import math logger = logging.get_logger(__name__) ##https://github.com/huggingface/transformers/blob/main/src/transformers/models/mpt/modeling_mpt.py def build_mpt_alibi_tensor(num_heads, sequence_length, alibi_bias_max=8, device=None): r""" Link to paper: https://arxiv.org/abs/2108.12409 - Alibi tensor is not causal as the original paper mentions, it relies on a translation invariance of softmax for quick implementation. This implementation has been copied from the alibi implementation of MPT source code that led to slightly different results than the Bloom alibi: https://huggingface.co/mosaicml/mpt-7b/blob/main/attention.py#L292 """ alibi = torch.arange(1 - sequence_length, 1, dtype=torch.int32, device=device).view(1, 1, 1, sequence_length) num_heads_power_of_2 = 2 ** math.ceil(math.log2(num_heads)) base = torch.arange(1, num_heads_power_of_2 + 1, dtype=torch.float32, device=device) base = base * (alibi_bias_max / num_heads_power_of_2) slopes = 1.0 / torch.pow(2, base) slopes = slopes.view(1, num_heads, 1, 1) if num_heads_power_of_2 != num_heads: slopes = torch.concat([slopes[1::2], slopes[::2]])[:num_heads] alibi = alibi * slopes return alibi.squeeze(0) class GPTAlibiAttention(nn.Module): def __init__(self, config): super().__init__() self.config = config self.num_attention_heads = config.num_attention_heads self.hidden_size = config.hidden_size if self.hidden_size % self.num_attention_heads != 0: raise ValueError( "The hidden size is not divisble by the number of attention heads! Make sure to update them" ) self.head_size = self.hidden_size // self.num_attention_heads self.rotary_ndims = int(self.head_size * config.rotary_pct) self._init_bias(config.max_position_embeddings) self.register_buffer("masked_bias", torch.tensor(-1e9), persistent=False) self.norm_factor = self.head_size**-0.5 self.query_key_value = nn.Linear(config.hidden_size, 3 * config.hidden_size) self.dense = nn.Linear(config.hidden_size, config.hidden_size) self.attention_dropout = nn.Dropout(config.attention_dropout) def build_mpt_alibi_tensor(self, num_heads, sequence_length, alibi_bias_max=8, device=None): return build_mpt_alibi_tensor(num_heads, sequence_length, alibi_bias_max, device) def _init_bias(self, max_positions, device=None): self.register_buffer( "bias", torch.tril(torch.ones((max_positions, max_positions), dtype=torch.bool)).view( 1, 1, max_positions, max_positions ), persistent=False, ) if device is not None: self.bias = self.bias.to(device) def forward( self, hidden_states: torch.FloatTensor, attention_mask: torch.FloatTensor, position_ids: torch.LongTensor, head_mask: Optional[torch.FloatTensor] = None, layer_past: Optional[Tuple[torch.Tensor]] = None, use_cache: Optional[bool] = False, output_attentions: Optional[bool] = False, ): has_layer_past = layer_past is not None # Compute QKV # Attention heads [batch, seq_len, hidden_size] # --> [batch, seq_len, (np * 3 * head_size)] qkv = self.query_key_value(hidden_states) # [batch, seq_len, (num_heads * 3 * head_size)] # --> [batch, seq_len, num_heads, 3 * head_size] new_qkv_shape = qkv.size()[:-1] + (self.num_attention_heads, 3 * self.head_size) qkv = qkv.view(*new_qkv_shape) # [batch, seq_len, num_attention_heads, 3 * head_size] --> 3 [batch, num_attention_heads, seq_len, head_size] query = qkv[..., : self.head_size].permute(0, 2, 1, 3) key = qkv[..., self.head_size : 2 * self.head_size].permute(0, 2, 1, 3) value = qkv[..., 2 * self.head_size :].permute(0, 2, 1, 3) # Compute rotary embeddings on rotary_ndims query_rot = query[..., : self.rotary_ndims] query_pass = query[..., self.rotary_ndims :] key_rot = key[..., : self.rotary_ndims] key_pass = key[..., self.rotary_ndims :] # Compute token offset for rotary embeddings (when decoding) seq_len = key.shape[-2] if has_layer_past: seq_len += layer_past[0].shape[-2] query = torch.cat((query, query_pass), dim=-1) key = torch.cat((key, key_pass), dim=-1) # Cache QKV values if has_layer_past: past_key = layer_past[0] past_value = layer_past[1] key = torch.cat((past_key, key), dim=-2) value = torch.cat((past_value, value), dim=-2) present = (key, value) if use_cache else None # Compute attention attn_output, attn_weights = self._attn(query, key, value, attention_mask, head_mask) # Reshape outputs attn_output = self._merge_heads(attn_output, self.num_attention_heads, self.head_size) attn_output = self.dense(attn_output) outputs = (attn_output, present) if output_attentions: outputs += (attn_weights,) return outputs @classmethod def _split_heads(cls, tensor, num_attention_heads, attn_head_size): """ Splits hidden dim into attn_head_size and num_attention_heads """ # tensor: [bs, seq_len, hidden_size] new_shape = tensor.size()[:-1] + (num_attention_heads, attn_head_size) # -> [bs, seq_len, num_attention_heads, attn_head_size] tensor = tensor.view(new_shape) # -> [bs, num_attention_heads, seq_len, attn_head_size] tensor = tensor.permute(0, 2, 1, 3) return tensor @classmethod def _merge_heads(cls, tensor, num_attention_heads, attn_head_size): """ Merges attn_head_size dim and num_attn_heads dim into hidden dim """ # tensor [bs, num_attention_heads, seq_len, attn_head_size] tensor = tensor.permute(0, 2, 1, 3).contiguous() # -> [bs, seq_len, num_attention_heads, attn_head_size] tensor = tensor.view(tensor.size(0), tensor.size(1), num_attention_heads * attn_head_size) # -> [bs, seq_len, hidden_size] return tensor def _attn(self, query, key, value, attention_mask=None, head_mask=None): # q, k, v: [bs, num_attention_heads, seq_len, attn_head_size] # compute causal mask from causal mask buffer batch_size, num_attention_heads, query_length, attn_head_size = query.size() key_length = key.size(-2) # dynamically increase the causal mask with the key length, if needed. if key_length > self.bias.shape[-1]: self._init_bias(key_length, device=key.device) ##ALIBI # this is called position bias in mpt code alibi = self.build_mpt_alibi_tensor(self.num_attention_heads, self.config.max_position_embeddings, device=query.device) causal_mask = self.bias[:, :, key_length - query_length : key_length, :key_length] query = query.view(batch_size * num_attention_heads, query_length, attn_head_size) key = key.view(batch_size * num_attention_heads, key_length, attn_head_size) attn_scores = torch.zeros( batch_size * num_attention_heads, query_length, key_length, dtype=query.dtype, device=key.device, ) attn_scores = torch.baddbmm( attn_scores, query, key.transpose(1, 2), beta=1.0, alpha=self.norm_factor, ) attn_scores = attn_scores.view(batch_size, num_attention_heads, query_length, key_length) ##adding alibi here position_bias_query_index = max(0, alibi.size(1) - query_length) position_bias_key_index = max(0, alibi.size(2) - key_length) alibi = alibi[:, position_bias_query_index:, position_bias_key_index:] attn_scores = attn_scores + alibi ##end of adding alibi mask_value = torch.finfo(attn_scores.dtype).min # Need to be a tensor, otherwise we get error: `RuntimeError: expected scalar type float but found double`. # Need to be on the same device, otherwise `RuntimeError: ..., x and y to be on the same device` mask_value = torch.tensor(mask_value, dtype=attn_scores.dtype).to(attn_scores.device) attn_scores = torch.where(causal_mask, attn_scores, mask_value) if attention_mask is not None: # Apply the attention mask attn_scores = attn_scores + attention_mask attn_weights = nn.functional.softmax(attn_scores, dim=-1) attn_weights = attn_weights.to(value.dtype) # Mask heads if we want to if head_mask is not None: attn_weights = attn_weights * head_mask #print(f"ATTN WEIGHTS {attn_weights[0][0]}") #ferkn attn_weights = self.attention_dropout(attn_weights) attn_output = torch.matmul(attn_weights, value) return attn_output, attn_weights class GPTNeoXAlibiLayer(nn.Module): def __init__(self, config): super().__init__() self.use_parallel_residual = config.use_parallel_residual self.input_layernorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps) self.post_attention_layernorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps) self.post_attention_dropout = nn.Dropout(config.hidden_dropout) self.post_mlp_dropout = nn.Dropout(config.hidden_dropout) self.attention = GPTAlibiAttention(config) self.mlp = GPTNeoXMLP(config) def forward( self, hidden_states: Optional[torch.FloatTensor], attention_mask: Optional[torch.FloatTensor] = None, position_ids: Optional[torch.LongTensor] = None, head_mask: Optional[torch.FloatTensor] = None, use_cache: Optional[bool] = False, layer_past: Optional[Tuple[torch.Tensor]] = None, output_attentions: Optional[bool] = False, ): attention_layer_outputs = self.attention( self.input_layernorm(hidden_states), attention_mask=attention_mask, position_ids=position_ids, layer_past=layer_past, head_mask=head_mask, use_cache=use_cache, output_attentions=output_attentions, ) attn_output = attention_layer_outputs[0] # output_attn: attn_output, present, (attn_weights) attn_output = self.post_attention_dropout(attn_output) outputs = attention_layer_outputs[1:] if self.use_parallel_residual: # pseudocode: # x = x + attn(ln1(x)) + mlp(ln2(x)) mlp_output = self.mlp(self.post_attention_layernorm(hidden_states)) mlp_output = self.post_mlp_dropout(mlp_output) hidden_states = mlp_output + attn_output + hidden_states else: # pseudocode: # x = x + attn(ln1(x)) # x = x + mlp(ln2(x)) attn_output = attn_output + hidden_states mlp_output = self.mlp(self.post_attention_layernorm(attn_output)) mlp_output = self.post_mlp_dropout(mlp_output) hidden_states = mlp_output + attn_output if use_cache: outputs = (hidden_states,) + outputs # hidden_states, present, (attn_weights) else: outputs = (hidden_states,) + outputs[1:] # hidden_states, (attn_weights) return outputs class GPTNeoXAlibiModel(GPTNeoXPreTrainedModel): def __init__(self, config): super().__init__(config) self.config = config self.embed_in = nn.Embedding(config.vocab_size, config.hidden_size) self.emb_dropout = nn.Dropout(config.hidden_dropout) self.layers = nn.ModuleList([GPTNeoXAlibiLayer(config) for _ in range(config.num_hidden_layers)]) self.final_layer_norm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps) self.gradient_checkpointing = False # Initialize weights and apply final processing self.post_init() def get_input_embeddings(self): return self.embed_in def set_input_embeddings(self, value): self.embed_in = value def forward( self, input_ids: Optional[torch.LongTensor] = None, attention_mask: Optional[torch.FloatTensor] = None, position_ids: Optional[torch.LongTensor] = None, head_mask: Optional[torch.FloatTensor] = None, inputs_embeds: Optional[torch.FloatTensor] = None, past_key_values: Optional[Tuple[Tuple[torch.FloatTensor]]] = None, use_cache: Optional[bool] = None, output_attentions: Optional[bool] = None, output_hidden_states: Optional[bool] = None, return_dict: Optional[bool] = None, ) -> Union[Tuple, BaseModelOutputWithPast]: r""" past_key_values (`tuple(tuple(torch.FloatTensor))` of length `config.n_layers` with each tuple having 4 tensors of shape `(batch_size, num_heads, sequence_length - 1, embed_size_per_head)`): Contains precomputed key and value hidden states of the attention blocks. Can be used to speed up decoding. If `past_key_values` are used, the user can optionally input only the last `decoder_input_ids` (those that don't have their past key value states given to this model) of shape `(batch_size, 1)` instead of all `decoder_input_ids` of shape `(batch_size, sequence_length)`. use_cache (`bool`, *optional*): If set to `True`, `past_key_values` key value states are returned and can be used to speed up decoding (see `past_key_values`). """ output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions output_hidden_states = ( output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states ) return_dict = return_dict if return_dict is not None else self.config.use_return_dict use_cache = use_cache if use_cache is not None else self.config.use_cache if input_ids is not None and inputs_embeds is not None: raise ValueError("You cannot specify both input_ids and inputs_embeds at the same time") elif input_ids is not None: self.warn_if_padding_and_no_attention_mask(input_ids, attention_mask) input_shape = input_ids.size() elif inputs_embeds is not None: input_shape = inputs_embeds.size()[:-1] else: raise ValueError("You have to specify either input_ids or inputs_embeds") batch_size, seq_length = input_shape if past_key_values is None: past_length = 0 past_key_values = tuple([None] * self.config.num_hidden_layers) else: past_length = past_key_values[0][0].size(-2) if position_ids is None: device = input_ids.device if input_ids is not None else inputs_embeds.device position_ids = torch.arange(past_length, seq_length + past_length, dtype=torch.long, device=device) position_ids = position_ids.unsqueeze(0) # Attention mask. if attention_mask is not None: assert batch_size > 0, "batch_size has to be defined and > 0" attention_mask = attention_mask.view(batch_size, -1) # We create a 3D attention mask from a 2D tensor mask. # Sizes are [batch_size, 1, 1, to_seq_length] # So we can broadcast to [batch_size, num_heads, from_seq_length, to_seq_length] # this attention mask is more simple than the triangular masking of causal attention # used in OpenAI GPT, we just need to prepare the broadcast dimension here. attention_mask = attention_mask[:, None, None, :] # Since attention_mask is 1.0 for positions we want to attend and 0.0 for # masked positions, this operation will create a tensor which is 0.0 for # positions we want to attend and the dtype's smallest value for masked positions. # Since we are adding it to the raw scores before the softmax, this is # effectively the same as removing these entirely. attention_mask = attention_mask.to(dtype=self.dtype) # fp16 compatibility attention_mask = (1.0 - attention_mask) * torch.finfo(self.dtype).min # Prepare head mask if needed # 1.0 in head_mask indicate we keep the head # attention_probs has shape bsz x n_heads x N x N # input head_mask has shape [num_heads] or [num_hidden_layers x num_heads] # and head_mask is converted to shape [num_hidden_layers x batch x num_heads x seq_length x seq_length] head_mask = self.get_head_mask(head_mask, self.config.num_hidden_layers) if inputs_embeds is None: inputs_embeds = self.embed_in(input_ids) hidden_states = self.emb_dropout(inputs_embeds) if self.gradient_checkpointing and self.training: if use_cache: logger.warning( "`use_cache=True` is incompatible with gradient checkpointing. Setting `use_cache=False`..." ) use_cache = False presents = () if use_cache else None all_attentions = () if output_attentions else None all_hidden_states = () if output_hidden_states else None for i, (layer, layer_past) in enumerate(zip(self.layers, past_key_values)): if output_hidden_states: all_hidden_states = all_hidden_states + (hidden_states,) if self.gradient_checkpointing and self.training: outputs = self._gradient_checkpointing_func( layer.__call__, hidden_states, attention_mask, position_ids, head_mask[i], use_cache, None, output_attentions, ) else: outputs = layer( hidden_states, attention_mask=attention_mask, position_ids=position_ids, head_mask=head_mask[i], layer_past=layer_past, use_cache=use_cache, output_attentions=output_attentions, ) hidden_states = outputs[0] if use_cache is True: presents = presents + (outputs[1],) if output_attentions: all_attentions = all_attentions + (outputs[2 if use_cache else 1],) hidden_states = self.final_layer_norm(hidden_states) # Add last hidden state if output_hidden_states: all_hidden_states = all_hidden_states + (hidden_states,) if not return_dict: return tuple(v for v in [hidden_states, presents, all_hidden_states, all_attentions] if v is not None) return BaseModelOutputWithPast( last_hidden_state=hidden_states, past_key_values=presents, hidden_states=all_hidden_states, attentions=all_attentions, ) class GPTNeoXAlibiForCausalLM(GPTNeoXPreTrainedModel): _tied_weights_keys = ["embed_out.weight"] def __init__(self, config): super().__init__(config) self.gpt_neox = GPTNeoXAlibiModel(config) self.embed_out = nn.Linear(config.hidden_size, config.vocab_size, bias=False) # Initialize weights and apply final processing self.post_init() def get_output_embeddings(self): return self.embed_out def set_output_embeddings(self, new_embeddings): self.embed_out = new_embeddings def forward( self, input_ids: Optional[torch.LongTensor] = None, attention_mask: Optional[torch.FloatTensor] = None, position_ids: Optional[torch.LongTensor] = None, inputs_embeds: Optional[torch.FloatTensor] = None, head_mask: Optional[torch.FloatTensor] = None, past_key_values: Optional[Tuple[Tuple[torch.FloatTensor]]] = None, labels: Optional[torch.LongTensor] = None, use_cache: Optional[bool] = None, output_attentions: Optional[bool] = None, output_hidden_states: Optional[bool] = None, return_dict: Optional[bool] = None, ) -> Union[Tuple, CausalLMOutputWithPast]: r""" past_key_values (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`): Tuple of `tuple(torch.FloatTensor)` of length `config.n_layers`, with each tuple having 2 tensors of shape `(batch_size, num_heads, sequence_length, embed_size_per_head)`) and 2 additional tensors of shape `(batch_size, num_heads, encoder_sequence_length, embed_size_per_head)`. The two additional tensors are only required when the model is used as a decoder in a Sequence to Sequence model. Contains pre-computed hidden-states (key and values in the self-attention blocks that can be used (see `past_key_values` input) to speed up sequential decoding. If `past_key_values` are used, the user can optionally input only the last `decoder_input_ids` (those that don't have their past key value states given to this model) of shape `(batch_size, 1)` instead of all `decoder_input_ids` of shape `(batch_size, sequence_length)`. labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*): Labels for computing the left-to-right language modeling loss (next word prediction). Indices should be in `[-100, 0, ..., config.vocab_size]` (see `input_ids` docstring) Tokens with indices set to `-100` are ignored (masked), the loss is only computed for the tokens with labels n `[0, ..., config.vocab_size]`. use_cache (`bool`, *optional*): If set to `True`, `past_key_values` key value states are returned and can be used to speed up decoding (see `past_key_values`). Returns: Example: ```python >>> from transformers import AutoTokenizer, GPTNeoXForCausalLM, GPTNeoXConfig >>> import torch >>> tokenizer = AutoTokenizer.from_pretrained("EleutherAI/gpt-neox-20b") >>> config = GPTNeoXConfig.from_pretrained("EleutherAI/gpt-neox-20b") >>> config.is_decoder = True >>> model = GPTNeoXForCausalLM.from_pretrained("EleutherAI/gpt-neox-20b", config=config) >>> inputs = tokenizer("Hello, my dog is cute", return_tensors="pt") >>> outputs = model(**inputs) >>> prediction_logits = outputs.logits ```""" return_dict = return_dict if return_dict is not None else self.config.use_return_dict outputs = self.gpt_neox( input_ids, attention_mask=attention_mask, position_ids=position_ids, head_mask=head_mask, inputs_embeds=inputs_embeds, past_key_values=past_key_values, use_cache=use_cache, output_attentions=output_attentions, output_hidden_states=output_hidden_states, return_dict=return_dict, ) hidden_states = outputs[0] lm_logits = self.embed_out(hidden_states) lm_loss = None if labels is not None: # move labels to correct device to enable model parallelism labels = labels.to(lm_logits.device) # we are doing next-token prediction; shift prediction scores and input ids by one shift_logits = lm_logits[:, :-1, :].contiguous() labels = labels[:, 1:].contiguous() loss_fct = CrossEntropyLoss() lm_loss = loss_fct(shift_logits.view(-1, shift_logits.size(-1)), labels.view(-1)) if not return_dict: output = (lm_logits,) + outputs[1:] return ((lm_loss,) + output) if lm_loss is not None else output return CausalLMOutputWithPast( loss=lm_loss, logits=lm_logits, past_key_values=outputs.past_key_values, hidden_states=outputs.hidden_states, attentions=outputs.attentions, ) def prepare_inputs_for_generation( self, input_ids, past_key_values=None, attention_mask=None, inputs_embeds=None, **kwargs ): input_shape = input_ids.shape # cut decoder_input_ids if past is used if past_key_values is not None: past_length = past_key_values[0][0].shape[2] # Some generation methods already pass only the last input ID if input_ids.shape[1] > past_length: remove_prefix_length = past_length else: # Default to old behavior: keep only final ID remove_prefix_length = input_ids.shape[1] - 1 input_ids = input_ids[:, remove_prefix_length:] position_ids = kwargs.get("position_ids", None) if attention_mask is not None and position_ids is None: # create position_ids on the fly for batch generation position_ids = attention_mask.long().cumsum(-1) - 1 position_ids.masked_fill_(attention_mask == 0, 1) if past_key_values: position_ids = position_ids[:, -input_ids.shape[1] :] # if model is used as a decoder in encoder-decoder model, the decoder attention mask is created on the fly if attention_mask is None: attention_mask = input_ids.new_ones(input_shape) # if `inputs_embeds` are passed, we only want to use them in the 1st generation step if inputs_embeds is not None and past_key_values is None: model_inputs = {"inputs_embeds": inputs_embeds} else: model_inputs = {"input_ids": input_ids} model_inputs.update( { "attention_mask": attention_mask, "past_key_values": past_key_values, "position_ids": position_ids, } ) return model_inputs def _reorder_cache(self, past_key_values, beam_idx): reordered_past = () for layer_past in past_key_values: reordered_past += ( tuple(past_state.index_select(0, beam_idx.to(past_state.device)) for past_state in layer_past[:2]) + layer_past[2:], ) return reordered_past