Spaces:

flax-community
/

image-captioning

Runtime error

image-captioning / vit_gpt2 /modeling_flax_gpt2.py

ydshieh

try load model from hub

e755009 almost 3 years ago

No virus

31.3 kB

	# coding=utf-8
	# Copyright 2021 The Google Flax Team Authors and The HuggingFace Inc. team.
	#
	# Licensed under the Apache License, Version 2.0 (the "License");
	# you may not use this file except in compliance with the License.
	# You may obtain a copy of the License at
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS,
	# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	# See the License for the specific language governing permissions and
	# limitations under the License.

	from typing import Any, Optional, Tuple

	import flax.linen as nn
	import jax
	import jax.numpy as jnp
	from flax.core.frozen_dict import FrozenDict, unfreeze
	from flax.linen import combine_masks, make_causal_mask
	from flax.linen.attention import dot_product_attention_weights
	from jax import lax

	from transformers.file_utils import add_start_docstrings, add_start_docstrings_to_model_forward
	from transformers.modeling_flax_outputs import FlaxBaseModelOutput, FlaxBaseModelOutputWithPast, FlaxCausalLMOutput, FlaxBaseModelOutputWithPastAndCrossAttentions, FlaxSeq2SeqLMOutput
	from transformers.modeling_flax_utils import ACT2FN, FlaxPreTrainedModel, append_call_sample_docstring
	from transformers.utils import logging
	from transformers.models.gpt2.configuration_gpt2 import GPT2Config


	logger = logging.get_logger(__name__)

	_CHECKPOINT_FOR_DOC = "gpt2"
	_CONFIG_FOR_DOC = "GPT2Config"
	_TOKENIZER_FOR_DOC = "GPT2Tokenizer"


	GPT2_START_DOCSTRING = r"""

	This model inherits from :class:`~transformers.FlaxPreTrainedModel`. Check the superclass documentation for the
	generic methods the library implements for all its model (such as downloading or saving, resizing the input
	embeddings, pruning heads etc.)

	This model is also a Flax Linen `flax.nn.Module
	<https://flax.readthedocs.io/en/latest/_autosummary/flax.nn.module.html>`__ subclass. Use it as a regular Flax
	Module and refer to the Flax documentation for all matter related to general usage and behavior.

	Finally, this model supports inherent JAX features such as:

	- `Just-In-Time (JIT) compilation <https://jax.readthedocs.io/en/latest/jax.html#just-in-time-compilation-jit>`__
	- `Automatic Differentiation <https://jax.readthedocs.io/en/latest/jax.html#automatic-differentiation>`__
	- `Vectorization <https://jax.readthedocs.io/en/latest/jax.html#vectorization-vmap>`__
	- `Parallelization <https://jax.readthedocs.io/en/latest/jax.html#parallelization-pmap>`__

	Parameters:
	config (:class:`~transformers.GPT2Config`): Model configuration class with all the parameters of the model.
	Initializing with a config file does not load the weights associated with the model, only the
	configuration. Check out the :meth:`~transformers.FlaxPreTrainedModel.from_pretrained` method to load the
	model weights.
	"""

	GPT2_INPUTS_DOCSTRING = r"""
	Args:
	input_ids (:obj:`numpy.ndarray` of shape :obj:`(batch_size, input_ids_length)`):
	:obj:`input_ids_length` = ``sequence_length``. Indices of input sequence tokens in the vocabulary.

	Indices can be obtained using :class:`~transformers.GPT2Tokenizer`. See
	:meth:`transformers.PreTrainedTokenizer.encode` and :meth:`transformers.PreTrainedTokenizer.__call__` for
	details.

	`What are input IDs? <../glossary.html#input-ids>`__
	attention_mask (:obj:`numpy.ndarray` of shape :obj:`(batch_size, sequence_length)`, `optional`):
	Mask to avoid performing attention on padding token indices. Mask values selected in ``[0, 1]``:

	- 1 for tokens that are not masked,
	- 0 for tokens that are masked.

	`What are attention masks? <../glossary.html#attention-mask>`__
	position_ids (:obj:`numpy.ndarray` of shape :obj:`(batch_size, sequence_length)`, `optional`):
	Indices of positions of each input sequence tokens in the position embeddings. Selected in the range ``[0,
	config.max_position_embeddings - 1]``.
	past_key_values (:obj:`Dict[str, np.ndarray]`, `optional`, returned by ``init_cache`` or when passing previous ``past_key_values``):
	Dictionary of pre-computed hidden-states (key and values in the attention blocks) that can be used for fast
	auto-regressive decoding. Pre-computed key and value hidden-states are of shape `[batch_size, max_length]`.
	output_attentions (:obj:`bool`, `optional`):
	Whether or not to return the attentions tensors of all attention layers. See ``attentions`` under returned
	tensors for more detail.
	output_hidden_states (:obj:`bool`, `optional`):
	Whether or not to return the hidden states of all layers. See ``hidden_states`` under returned tensors for
	more detail.
	return_dict (:obj:`bool`, `optional`):
	Whether or not to return a :class:`~transformers.file_utils.ModelOutput` instead of a plain tuple.
	"""


	class FlaxConv1D(nn.Module):
	features: int
	use_bias: bool = True
	dtype: Any = jnp.float32
	precision: Any = None

	@nn.compact
	def __call__(self, inputs):
	inputs = jnp.asarray(inputs, self.dtype)
	kernel = self.param("kernel", jax.nn.initializers.normal(stddev=0.02), (self.features, inputs.shape[-1]))
	kernel = jnp.asarray(kernel.transpose(), self.dtype)
	y = lax.dot_general(inputs, kernel, (((inputs.ndim - 1,), (0,)), ((), ())), precision=self.precision)
	if self.use_bias:
	bias = self.param("bias", jax.nn.initializers.zeros, (self.features,))
	bias = jnp.asarray(bias, self.dtype)
	y = y + bias
	return y


	class FlaxGPT2Attention(nn.Module):
	config: GPT2Config
	dtype: jnp.dtype = jnp.float32
	causal: bool = True

	def setup(self):
	config = self.config
	self.embed_dim = config.hidden_size
	self.num_heads = config.num_attention_heads
	self.head_dim = self.embed_dim // self.num_heads

	self.c_attn = FlaxConv1D(features=3 * self.embed_dim, dtype=self.dtype)
	self.c_proj = FlaxConv1D(self.embed_dim, dtype=self.dtype)

	self.c_attn_for_k_v = FlaxConv1D(features=2 * self.embed_dim, dtype=self.dtype)

	self.resid_dropout = nn.Dropout(rate=config.resid_pdrop)

	if self.causal:
	self.causal_mask = make_causal_mask(jnp.ones((1, config.max_position_embeddings), dtype="bool"), dtype="bool")

	def _split_heads(self, hidden_states):
	return hidden_states.reshape(hidden_states.shape[:2] + (self.num_heads, self.head_dim))

	def _merge_heads(self, hidden_states):
	return hidden_states.reshape(hidden_states.shape[:2] + (self.embed_dim,))

	@nn.compact
	def _concatenate_to_cache(self, key, value, query, attention_mask):
	"""
	This function takes projected key, value states from a single input token and concatenates the states to cached
	states from previous steps. This function is slighly adapted from the official Flax repository:
	https://github.com/google/flax/blob/491ce18759622506588784b4fca0e4bf05f8c8cd/flax/linen/attention.py#L252
	"""
	# detect if we're initializing by absence of existing cache data.
	is_initialized = self.has_variable("cache", "cached_key")
	cached_key = self.variable("cache", "cached_key", jnp.zeros, key.shape, key.dtype)
	cached_value = self.variable("cache", "cached_value", jnp.zeros, value.shape, value.dtype)
	cache_index = self.variable("cache", "cache_index", lambda: jnp.array(0, dtype=jnp.int32))

	if is_initialized:
	*batch_dims, max_length, num_heads, depth_per_head = cached_key.value.shape
	# update key, value caches with our new 1d spatial slices
	cur_index = cache_index.value
	indices = (0,) * len(batch_dims) + (cur_index, 0, 0)
	key = lax.dynamic_update_slice(cached_key.value, key, indices)
	value = lax.dynamic_update_slice(cached_value.value, value, indices)
	cached_key.value = key
	cached_value.value = value
	num_updated_cache_vectors = query.shape[1]
	cache_index.value = cache_index.value + num_updated_cache_vectors
	# causal mask for cached decoder self-attention: our single query position should only attend to those key positions that have already been generated and cached, not the remaining zero elements.
	pad_mask = jnp.broadcast_to(
	jnp.arange(max_length) < cur_index + num_updated_cache_vectors,
	tuple(batch_dims) + (1, num_updated_cache_vectors, max_length),
	)
	attention_mask = combine_masks(pad_mask, attention_mask)
	return key, value, attention_mask

	def __call__(
	self,
	hidden_states,
	key_value_states: Optional[jnp.ndarray] = None,
	attention_mask=None,
	deterministic: bool = True,
	init_cache: bool = False,
	output_attentions: bool = False,
	):

	# if key_value_states are provided this layer is used as a cross-attention layer
	# for the decoder
	is_cross_attention = key_value_states is not None

	qkv_out = self.c_attn(hidden_states)
	query, key, value = jnp.split(qkv_out, 3, axis=2)

	if is_cross_attention:
	_qkv_out = self.c_attn_for_k_v(key_value_states)
	key, value = jnp.split(_qkv_out, 2, axis=2)

	query = self._split_heads(query)
	key = self._split_heads(key)
	value = self._split_heads(value)

	query_length, key_length = query.shape[1], key.shape[1]

	if self.causal:
	if self.has_variable("cache", "cached_key"):
	mask_shift = self.variables["cache"]["cache_index"]
	max_decoder_length = self.variables["cache"]["cached_key"].shape[1]
	causal_mask = lax.dynamic_slice(
	self.causal_mask, (0, 0, mask_shift, 0), (1, 1, query_length, max_decoder_length)
	)
	else:
	causal_mask = self.causal_mask[:, :, :query_length, :key_length]

	batch_size = hidden_states.shape[0]
	causal_mask = jnp.broadcast_to(causal_mask, (batch_size,) + causal_mask.shape[1:])

	# combine masks if needed
	if attention_mask is not None and self.causal:
	attention_mask = jnp.broadcast_to(jnp.expand_dims(attention_mask, axis=(-3, -2)), causal_mask.shape)
	attention_mask = combine_masks(attention_mask, causal_mask)
	elif self.causal:
	attention_mask = causal_mask
	elif attention_mask is not None:
	attention_mask = jnp.expand_dims(attention_mask, axis=(-3, -2))

	dropout_rng = None
	if not deterministic and self.config.attn_pdrop > 0.0:
	dropout_rng = self.make_rng("dropout")

	# During fast autoregressive decoding, we feed one position at a time,
	# and cache the keys and values step by step.
	if self.causal and (self.has_variable("cache", "cached_key") or init_cache):
	key, value, attention_mask = self._concatenate_to_cache(key, value, query, attention_mask)

	# transform boolean mask into float mask
	if attention_mask is not None:
	attention_bias = lax.select(
	attention_mask > 0,
	jnp.full(attention_mask.shape, 0.0).astype(self.dtype),
	jnp.full(attention_mask.shape, -1e4).astype(self.dtype),
	)
	else:
	attention_bias = None

	# usual dot product attention
	attn_weights = dot_product_attention_weights(
	query,
	key,
	bias=attention_bias,
	dropout_rng=dropout_rng,
	dropout_rate=self.config.attn_pdrop,
	deterministic=deterministic,
	dtype=self.dtype,
	precision=None,
	)

	attn_output = jnp.einsum("...hqk,...khd->...qhd", attn_weights, value)
	attn_output = self._merge_heads(attn_output)
	attn_output = self.c_proj(attn_output)
	attn_output = self.resid_dropout(attn_output, deterministic=deterministic)

	outputs = (attn_output, attn_weights) if output_attentions else (attn_output,)
	return outputs


	class FlaxGPT2MLP(nn.Module):
	config: GPT2Config
	intermediate_size: int
	dtype: jnp.dtype = jnp.float32

	def setup(self):
	embed_dim = self.config.hidden_size
	self.c_fc = FlaxConv1D(self.intermediate_size, dtype=self.dtype)
	self.c_proj = FlaxConv1D(embed_dim, dtype=self.dtype)
	self.act = ACT2FN[self.config.activation_function]
	self.dropout = nn.Dropout(rate=self.config.resid_pdrop)

	def __call__(self, hidden_states, deterministic: bool = True):
	hidden_states = self.c_fc(hidden_states)
	hidden_states = self.act(hidden_states)
	hidden_states = self.c_proj(hidden_states)
	hidden_states = self.dropout(hidden_states, deterministic=deterministic)
	return hidden_states


	class FlaxGPT2Block(nn.Module):
	config: GPT2Config
	dtype: jnp.dtype = jnp.float32

	def setup(self):
	hidden_size = self.config.hidden_size
	inner_dim = self.config.n_inner if self.config.n_inner is not None else 4 * hidden_size

	self.ln_1 = nn.LayerNorm(epsilon=self.config.layer_norm_epsilon, dtype=self.dtype)
	self.attn = FlaxGPT2Attention(self.config, dtype=self.dtype)
	self.ln_3 = nn.LayerNorm(epsilon=self.config.layer_norm_epsilon, dtype=self.dtype)
	self.encoder_attn = FlaxGPT2Attention(config=self.config, dtype=self.dtype)
	self.ln_2 = nn.LayerNorm(epsilon=self.config.layer_norm_epsilon, dtype=self.dtype)
	self.mlp = FlaxGPT2MLP(self.config, inner_dim, dtype=self.dtype)

	def __call__(
	self,
	hidden_states,
	attention_mask=None,
	encoder_hidden_states: Optional[jnp.ndarray] = None,
	encoder_attention_mask: Optional[jnp.ndarray] = None,
	deterministic: bool = True,
	init_cache: bool = False,
	output_attentions: bool = False,
	):
	residual = hidden_states
	hidden_states = self.ln_1(hidden_states)
	outputs = self.attn(
	hidden_states,
	attention_mask=attention_mask,
	deterministic=deterministic,
	init_cache=init_cache,
	output_attentions=output_attentions,
	)
	# residual connection
	attn_output = outputs[0]
	hidden_states = attn_output + residual

	# Cross-Attention Block
	if encoder_hidden_states is not None:

	residual = hidden_states
	hidden_states = self.ln_3(hidden_states)

	cross_attn_outputs = self.encoder_attn(
	hidden_states=hidden_states,
	key_value_states=encoder_hidden_states,
	attention_mask=encoder_attention_mask,
	deterministic=deterministic,
	output_attentions=output_attentions,
	)

	# residual connection
	cross_attn_output = cross_attn_outputs[0]
	hidden_states = cross_attn_output + residual

	residual = hidden_states
	hidden_states = self.ln_2(hidden_states)
	feed_forward_hidden_states = self.mlp(hidden_states, deterministic=deterministic)
	# residual connection
	hidden_states = residual + feed_forward_hidden_states

	output = (hidden_states,) + outputs[1:]
	if encoder_hidden_states is not None:
	output = output + cross_attn_outputs[1:]

	return output


	class FlaxGPT2PreTrainedModel(FlaxPreTrainedModel):
	"""
	An abstract class to handle weights initialization and a simple interface for downloading and loading pretrained
	models.
	"""

	config_class = GPT2Config
	base_model_prefix = "transformer"
	module_class: nn.Module = None

	def __init__(
	self,
	config: GPT2Config,
	input_shape: Tuple = (1, 1),
	seed: int = 0,
	dtype: jnp.dtype = jnp.float32,
	**kwargs,
	):
	module = self.module_class(config=config, dtype=dtype, **kwargs)
	super().__init__(config, module, input_shape=input_shape, seed=seed, dtype=dtype)

	def init_weights(self, rng: jax.random.PRNGKey, input_shape: Tuple) -> FrozenDict:
	# init input tensors
	input_ids = jnp.zeros(input_shape, dtype="i4")
	attention_mask = jnp.ones_like(input_ids)
	position_ids = jnp.broadcast_to(jnp.arange(jnp.atleast_2d(input_ids).shape[-1]), input_shape)
	params_rng, dropout_rng = jax.random.split(rng)
	rngs = {"params": params_rng, "dropout": dropout_rng}

	if self.config.add_cross_attention:
	encoder_hidden_states = jnp.zeros(input_shape + (self.config.n_embd,))
	encoder_attention_mask = attention_mask
	module_init_outputs = self.module.init(rngs, input_ids, attention_mask, position_ids, encoder_hidden_states, encoder_attention_mask, return_dict=False)
	else:
	module_init_outputs = self.module.init(rngs, input_ids, attention_mask, position_ids, return_dict=False)

	return module_init_outputs["params"]

	@classmethod
	def _from_config(cls, config, **kwargs):
	return super()._from_config(config, **kwargs)

	def init_cache(self, batch_size, max_length):
	r"""
	Args:
	batch_size (:obj:`int`):
	batch_size used for fast auto-regressive decoding. Defines the batch size of the initialized cache.
	max_length (:obj:`int`):
	maximum possible length for auto-regressive decoding. Defines the sequence length of the initialized
	cache.
	"""
	# init input variables to retrieve cache
	input_ids = jnp.ones((batch_size, max_length))
	attention_mask = jnp.ones_like(input_ids)
	position_ids = jnp.broadcast_to(jnp.arange(jnp.atleast_2d(input_ids).shape[-1]), input_ids.shape)

	init_variables = self.module.init(
	jax.random.PRNGKey(0), input_ids, attention_mask, position_ids, return_dict=False, init_cache=True
	)
	return init_variables["cache"]

	@add_start_docstrings_to_model_forward(GPT2_INPUTS_DOCSTRING)
	def __call__(
	self,
	input_ids,
	attention_mask=None,
	position_ids=None,
	encoder_hidden_states: Optional[jnp.ndarray] = None,
	encoder_attention_mask: Optional[jnp.ndarray] = None,
	params: dict = None,
	past_key_values: dict = None,
	dropout_rng: jax.random.PRNGKey = None,
	train: bool = False,
	output_attentions: Optional[bool] = None,
	output_hidden_states: Optional[bool] = None,
	return_dict: Optional[bool] = None,
	):
	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.return_dict

	if encoder_hidden_states is not None and encoder_attention_mask is None:
	batch_size, sequence_length = encoder_hidden_states.shape[:2]
	encoder_attention_mask = jnp.ones((batch_size, sequence_length))

	batch_size, sequence_length = input_ids.shape

	if position_ids is None:
	if past_key_values is not None:
	raise ValueError("Make sure to provide `position_ids` when passing `past_key_values`.")

	position_ids = jnp.broadcast_to(jnp.arange(sequence_length)[None, :], (batch_size, sequence_length))

	if attention_mask is None:
	attention_mask = jnp.ones((batch_size, sequence_length))

	# Handle any PRNG if needed
	rngs = {}
	if dropout_rng is not None:
	rngs["dropout"] = dropout_rng

	inputs = {"params": params or self.params}

	# if past_key_values are passed then cache is already initialized a private flag init_cache has to be passed down to ensure cache is used. It has to be made sure that cache is marked as mutable so that it can be changed by FlaxGPT2Attention module
	if past_key_values:
	inputs["cache"] = past_key_values
	mutable = ["cache"]
	else:
	mutable = False

	outputs = self.module.apply(
	inputs,
	jnp.array(input_ids, dtype="i4"),
	jnp.array(attention_mask, dtype="i4"),
	jnp.array(position_ids, dtype="i4"),
	encoder_hidden_states,
	encoder_attention_mask,
	not train,
	False,
	output_attentions,
	output_hidden_states,
	return_dict,
	rngs=rngs,
	mutable=mutable,
	)

	# add updated cache to model output
	if past_key_values is not None and return_dict:
	outputs, past_key_values = outputs
	outputs["past_key_values"] = unfreeze(past_key_values["cache"])
	return outputs
	elif past_key_values is not None and not return_dict:
	outputs, past_key_values = outputs
	outputs = outputs[:1] + (unfreeze(past_key_values["cache"]),) + outputs[1:]

	return outputs


	class FlaxGPT2BlockCollection(nn.Module):
	config: GPT2Config
	dtype: jnp.dtype = jnp.float32

	def setup(self):
	self.blocks = [
	FlaxGPT2Block(self.config, name=str(i), dtype=self.dtype) for i in range(self.config.num_hidden_layers)
	]

	def __call__(
	self,
	hidden_states,
	attention_mask=None,
	encoder_hidden_states: Optional[jnp.ndarray] = None,
	encoder_attention_mask: Optional[jnp.ndarray] = None,
	deterministic: bool = True,
	init_cache: bool = False,
	output_attentions: bool = False,
	output_hidden_states: bool = False,
	return_dict: bool = True,
	):
	all_attentions = () if output_attentions else None
	all_hidden_states = () if output_hidden_states else None
	all_cross_attentions = () if (output_attentions and encoder_hidden_states is not None) else None

	for block in self.blocks:
	if output_hidden_states:
	all_hidden_states += (hidden_states,)

	layer_outputs = block(
	hidden_states,
	attention_mask,
	encoder_hidden_states=encoder_hidden_states,
	encoder_attention_mask=encoder_attention_mask,
	deterministic=deterministic,
	init_cache=init_cache,
	output_attentions=output_attentions,
	)
	hidden_states = layer_outputs[0]

	if output_attentions:
	all_attentions += (layer_outputs[1],)
	if encoder_hidden_states is not None:
	all_cross_attentions += (layer_outputs[2],)

	if output_hidden_states:
	all_hidden_states += (hidden_states,)

	outputs = [hidden_states, all_hidden_states, all_attentions, all_cross_attentions]

	if not return_dict:
	return tuple(v for v in outputs if v is not None)

	if encoder_hidden_states is None:
	return FlaxBaseModelOutputWithPast(
	last_hidden_state=hidden_states,
	past_key_values=None,
	hidden_states=all_hidden_states,
	attentions=all_attentions,
	)
	else:
	return FlaxBaseModelOutputWithPastAndCrossAttentions(
	last_hidden_state=hidden_states,
	past_key_values=None,
	hidden_states=all_hidden_states,
	attentions=all_attentions,
	cross_attentions=all_cross_attentions,
	)

	class FlaxGPT2Module(nn.Module):
	config: GPT2Config
	dtype: jnp.dtype = jnp.float32

	def setup(self):
	self.embed_dim = self.config.hidden_size

	self.wte = nn.Embed(
	self.config.vocab_size,
	self.embed_dim,
	embedding_init=jax.nn.initializers.normal(stddev=self.config.initializer_range),
	dtype=self.dtype,
	)
	self.wpe = nn.Embed(
	self.config.max_position_embeddings,
	self.embed_dim,
	embedding_init=jax.nn.initializers.normal(stddev=self.config.initializer_range),
	dtype=self.dtype,
	)
	self.dropout = nn.Dropout(rate=self.config.embd_pdrop)
	self.h = FlaxGPT2BlockCollection(self.config, dtype=self.dtype)
	self.ln_f = nn.LayerNorm(epsilon=self.config.layer_norm_epsilon, dtype=self.dtype)

	def __call__(
	self,
	input_ids,
	attention_mask,
	position_ids,
	encoder_hidden_states: Optional[jnp.ndarray] = None,
	encoder_attention_mask: Optional[jnp.ndarray] = None,
	deterministic=True,
	init_cache: bool = False,
	output_attentions: bool = False,
	output_hidden_states: bool = False,
	return_dict: bool = True,
	):
	input_embeds = self.wte(input_ids.astype("i4"))
	position_embeds = self.wpe(position_ids.astype("i4"))

	hidden_states = input_embeds + position_embeds
	hidden_states = self.dropout(hidden_states, deterministic=deterministic)

	outputs = self.h(
	hidden_states,
	attention_mask,
	encoder_hidden_states,
	encoder_attention_mask,
	deterministic=deterministic,
	init_cache=init_cache,
	output_attentions=output_attentions,
	output_hidden_states=output_hidden_states,
	return_dict=return_dict,
	)

	hidden_states = outputs[0]
	hidden_states = self.ln_f(hidden_states)

	if not return_dict:
	return (hidden_states,) + outputs[1:]

	if encoder_hidden_states is None:
	return FlaxBaseModelOutput(
	last_hidden_state=hidden_states,
	hidden_states=outputs.hidden_states,
	attentions=outputs.attentions,
	)
	else:
	return FlaxBaseModelOutputWithPastAndCrossAttentions(
	last_hidden_state=hidden_states,
	hidden_states=outputs.hidden_states,
	attentions=outputs.attentions,
	cross_attentions=outputs.cross_attentions,
	)

	@add_start_docstrings(
	"The bare GPT2 Model transformer outputting raw hidden-states without any specific head on top.",
	GPT2_START_DOCSTRING,
	)
	class FlaxGPT2Model(FlaxGPT2PreTrainedModel):
	module_class = FlaxGPT2Module


	append_call_sample_docstring(
	FlaxGPT2Model, _TOKENIZER_FOR_DOC, _CHECKPOINT_FOR_DOC, FlaxBaseModelOutput, _CONFIG_FOR_DOC
	)


	class FlaxGPT2LMHeadModule(nn.Module):
	config: GPT2Config
	dtype: jnp.dtype = jnp.float32

	def setup(self):
	self.transformer = FlaxGPT2Module(self.config, dtype=self.dtype)
	self.lm_head = nn.Dense(
	self.config.vocab_size,
	use_bias=False,
	dtype=self.dtype,
	kernel_init=jax.nn.initializers.normal(stddev=self.config.initializer_range, dtype=self.dtype),
	)

	def __call__(
	self,
	input_ids,
	attention_mask,
	position_ids,
	encoder_hidden_states: Optional[jnp.ndarray] = None,
	encoder_attention_mask: Optional[jnp.ndarray] = None,
	deterministic: bool = True,
	init_cache: bool = False,
	output_attentions: bool = False,
	output_hidden_states: bool = False,
	return_dict: bool = True,
	):
	outputs = self.transformer(
	input_ids,
	attention_mask,
	position_ids,
	encoder_hidden_states,
	encoder_attention_mask,
	deterministic=deterministic,
	init_cache=init_cache,
	output_attentions=output_attentions,
	output_hidden_states=output_hidden_states,
	return_dict=return_dict,
	)

	hidden_states = outputs[0]

	if self.config.tie_word_embeddings:
	shared_kernel = self.transformer.variables["params"]["wte"]["embedding"].T
	lm_logits = self.lm_head.apply({"params": {"kernel": shared_kernel}}, hidden_states)
	else:
	lm_logits = self.lm_head(hidden_states)

	if not return_dict:
	return (lm_logits,) + outputs[1:]

	if encoder_hidden_states is None:
	return FlaxCausalLMOutput(logits=lm_logits, hidden_states=outputs.hidden_states, attentions=outputs.attentions)
	else:
	return FlaxSeq2SeqLMOutput(
	logits=lm_logits,
	decoder_hidden_states=outputs.hidden_states,
	decoder_attentions=outputs.attentions,
	cross_attentions=outputs.cross_attentions,
	encoder_last_hidden_state=encoder_hidden_states,
	encoder_hidden_states=None,
	encoder_attentions=None,
	)

	@add_start_docstrings(
	"""
	The GPT2 Model transformer with a language modeling head on top (linear layer with weights tied to the input
	embeddings).
	""",
	GPT2_START_DOCSTRING,
	)
	class FlaxGPT2LMHeadModel(FlaxGPT2PreTrainedModel):
	module_class = FlaxGPT2LMHeadModule

	def prepare_inputs_for_generation(self, input_ids, max_length, attention_mask: Optional[jnp.DeviceArray] = None):
	# initializing the cache
	batch_size, seq_length = input_ids.shape

	past_key_values = self.init_cache(batch_size, max_length)
	# Note that usually one would have to put 0's in the attention_mask for x > input_ids.shape[-1] and x < cache_length.
	# But since GPT2 uses a causal mask, those positions are masked anyways.
	# Thus we can create a single static attention_mask here, which is more efficient for compilation
	extended_attention_mask = jnp.ones((batch_size, max_length), dtype="i4")
	if attention_mask is not None:
	position_ids = attention_mask.cumsum(axis=-1) - 1
	extended_attention_mask = lax.dynamic_update_slice(extended_attention_mask, attention_mask, (0, 0))
	else:
	position_ids = jnp.broadcast_to(jnp.arange(seq_length, dtype="i4")[None, :], (batch_size, seq_length))

	return {
	"past_key_values": past_key_values,
	"attention_mask": extended_attention_mask,
	"position_ids": position_ids,
	}

	def update_inputs_for_generation(self, model_outputs, model_kwargs):
	model_kwargs["past_key_values"] = model_outputs.past_key_values
	model_kwargs["position_ids"] = model_kwargs["position_ids"][:, -1:] + 1
	return model_kwargs


	append_call_sample_docstring(
	FlaxGPT2LMHeadModel, _TOKENIZER_FOR_DOC, _CHECKPOINT_FOR_DOC, FlaxCausalLMOutput, _CONFIG_FOR_DOC
	)