# Copyright 2020 The Google AI Language Team Authors, Facebook AI Research authors and The HuggingFace Inc. team.
# Copyright (c) 2020, NVIDIA CORPORATION.  All rights reserved.
#
# 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.
import copy
import functools
import inspect
import os
import warnings
from collections.abc import Callable
from contextlib import contextmanager
from dataclasses import dataclass
from typing import TYPE_CHECKING, Any, Optional, cast

import torch
import torch.distributed as dist
from torch import nn

from ..cache_utils import (
    Cache,
    DynamicCache,
    EncoderDecoderCache,
    QuantizedCache,
    StaticCache,
)
from ..dynamic_module_utils import (
    check_python_requirements,
    get_cached_module_file,
    get_class_in_module,
    resolve_trust_remote_code,
)
from ..integrations.deepspeed import is_deepspeed_zero3_enabled
from ..integrations.fsdp import is_fsdp_managed_module
from ..masking_utils import create_masks_for_generate
from ..tokenization_python import ExtensionsTrie
from ..utils import (
    ModelOutput,
    TransformersKwargs,
    is_accelerate_available,
    logging,
)
from ..utils.generic import is_flash_attention_requested
from .candidate_generator import (
    AssistantVocabTranslatorCache,
    AssistedCandidateGenerator,
    AssistedCandidateGeneratorDifferentTokenizers,
    CandidateGenerator,
    EarlyExitCandidateGenerator,
    PromptLookupCandidateGenerator,
    SinglePositionMultiTokenCandidateGenerator,
    UniversalSpeculativeDecodingGenerator,
    _prepare_attention_mask,
    _prepare_position_ids,
    _prepare_token_type_ids,
)
from .configuration_utils import (
    ALL_STATIC_CACHE_IMPLEMENTATIONS,
    DEPRECATED_STATIC_CACHE_IMPLEMENTATIONS,
    STATIC_CACHE_IMPLEMENTATIONS,
    GenerationConfig,
    GenerationMode,
)
from .continuous_batching import ContinuousMixin
from .logits_process import (
    EncoderNoRepeatNGramLogitsProcessor,
    EncoderRepetitionPenaltyLogitsProcessor,
    EpsilonLogitsWarper,
    EtaLogitsWarper,
    ExponentialDecayLengthPenalty,
    ForcedBOSTokenLogitsProcessor,
    ForcedEOSTokenLogitsProcessor,
    InfNanRemoveLogitsProcessor,
    LogitNormalization,
    LogitsProcessorList,
    MinLengthLogitsProcessor,
    MinNewTokensLengthLogitsProcessor,
    MinPLogitsWarper,
    NoBadWordsLogitsProcessor,
    NoRepeatNGramLogitsProcessor,
    PrefixConstrainedLogitsProcessor,
    RepetitionPenaltyLogitsProcessor,
    SequenceBiasLogitsProcessor,
    SuppressTokensAtBeginLogitsProcessor,
    SuppressTokensLogitsProcessor,
    TemperatureLogitsWarper,
    TopHLogitsWarper,
    TopKLogitsWarper,
    TopPLogitsWarper,
    TypicalLogitsWarper,
    UnbatchedClassifierFreeGuidanceLogitsProcessor,
)
from .stopping_criteria import (
    ConfidenceCriteria,
    EosTokenCriteria,
    MaxLengthCriteria,
    MaxTimeCriteria,
    StoppingCriteria,
    StoppingCriteriaList,
    StopStringCriteria,
)


if TYPE_CHECKING:
    from .._typing import GenerativePreTrainedModel
    from ..modeling_utils import PreTrainedModel
    from ..tokenization_utils_base import PreTrainedTokenizerBase
    from .streamers import BaseStreamer

logger = logging.get_logger(__name__)

if is_accelerate_available():
    from accelerate.hooks import AlignDevicesHook, add_hook_to_module


# Variable names used to hold the cache at generation time
ALL_CACHE_NAMES = [
    "past_key_values",  # default
    "cache_params",  # mamba-based models
    "state",  # rwkv
    "mems",  # xlnet
    "past_buckets_states",  # reformer
]

GENERATION_MODES_MAPPING = {
    GenerationMode.SAMPLE: "_sample",
    GenerationMode.GREEDY_SEARCH: "_sample",
    GenerationMode.BEAM_SEARCH: "_beam_search",
    GenerationMode.BEAM_SAMPLE: "_beam_search",
    GenerationMode.ASSISTED_GENERATION: "_assisted_decoding",
    # Deprecated methods
    GenerationMode.DOLA_GENERATION: "transformers-community/dola",
    GenerationMode.CONTRASTIVE_SEARCH: "transformers-community/contrastive-search",
    GenerationMode.GROUP_BEAM_SEARCH: "transformers-community/group-beam-search",
    GenerationMode.CONSTRAINED_BEAM_SEARCH: "transformers-community/constrained-beam-search",
}


@dataclass
class GenerateDecoderOnlyOutput(ModelOutput):
    """
    Outputs of decoder-only generation models, when using non-beam methods.

    Args:
        sequences (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
            The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
            if all batches finished early due to the `eos_token_id`.
        scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True`):
            Processed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
            at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
            each generated token), with each tensor of shape `(batch_size, config.vocab_size)`.
        logits (`tuple(torch.FloatTensor)` *optional*, returned when `output_logits=True`):
            Unprocessed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
            at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
            each generated token), with each tensor of shape `(batch_size, config.vocab_size)`.
        attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True`):
            Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
            `torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
        hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True`):
            Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
            `torch.FloatTensor` of shape `(batch_size, generated_length, hidden_size)`.
        past_key_values (`Cache`, *optional*, returned when `use_cache=True`):
            Returns the model cache, used to speed up decoding. Different models have a different cache format, check
            the model's documentation. Usually, a [`~cache_utils.Cache`] instance.
    """

    sequences: torch.LongTensor
    scores: tuple[torch.FloatTensor] | None = None
    logits: tuple[torch.FloatTensor] | None = None
    attentions: tuple[tuple[torch.FloatTensor]] | None = None
    hidden_states: tuple[tuple[torch.FloatTensor]] | None = None
    past_key_values: Cache | None = None


@dataclass
class GenerateEncoderDecoderOutput(ModelOutput):
    """
    Outputs of encoder-decoder generation models, when using non-beam methods.

    Args:
        sequences (`torch.LongTensor` of shape `(batch_size*num_return_sequences, sequence_length)`):
            The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
            if all batches finished early due to the `eos_token_id`.
        scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True`):
            Processed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
            at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
            each generated token), with each tensor of shape `(batch_size, config.vocab_size)`.
        logits (`tuple(torch.FloatTensor)` *optional*, returned when `output_logits=True`):
            Unprocessed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
            at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
            each generated token), with each tensor of shape `(batch_size, config.vocab_size)`.
        encoder_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True`):
            Tuple of `torch.FloatTensor` (one for each layer of the decoder) of shape `(batch_size, num_heads,
            sequence_length, sequence_length)`.
        encoder_hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True`):
            Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of
            shape `(batch_size, sequence_length, hidden_size)`.
        decoder_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True`):
            Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
            `torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
        cross_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True`):
            Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
            `torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
        decoder_hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True`):
            Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
            `torch.FloatTensor` of shape `(batch_size, generated_length, hidden_size)`.
        past_key_values (`Cache`, *optional*, returned when `use_cache=True`):
            Returns the model cache, used to speed up decoding. Different models have a different cache format, check
            the model's documentation. Usually, a [`~cache_utils.Cache`] instance.
    """

    sequences: torch.LongTensor
    scores: tuple[torch.FloatTensor] | None = None
    logits: tuple[torch.FloatTensor] | None = None
    encoder_attentions: tuple[torch.FloatTensor] | None = None
    encoder_hidden_states: tuple[torch.FloatTensor] | None = None
    decoder_attentions: tuple[tuple[torch.FloatTensor]] | None = None
    cross_attentions: tuple[tuple[torch.FloatTensor]] | None = None
    decoder_hidden_states: tuple[tuple[torch.FloatTensor]] | None = None
    past_key_values: Cache | None = None


@dataclass
class GenerateBeamDecoderOnlyOutput(ModelOutput):
    """
    Outputs of decoder-only generation models, when using beam methods.

    Args:
        sequences (`torch.LongTensor` of shape `(batch_size*num_return_sequences, sequence_length)`):
            The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
            if all batches finished early due to the `eos_token_id`.
        sequences_scores (`torch.FloatTensor` of shape `(batch_size*num_return_sequences)`, *optional*, returned when `output_scores=True`):
            Final beam scores of the generated `sequences`.
        scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True`):
            Beam transition scores for each vocabulary token at each generation step. Beam transition scores consisting
            of log probabilities of tokens conditioned on log softmax of previously generated tokens in this beam.
            Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for each generated token),
            with each tensor of shape `(batch_size*num_beams, config.vocab_size)`.
        logits (`tuple(torch.FloatTensor)` *optional*, returned when `output_logits=True`):
            Unprocessed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
            at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
            each generated token), with each tensor of shape `(batch_size*num_beams, config.vocab_size)`.
        beam_indices (`torch.LongTensor`, *optional*, returned when `output_scores=True`):
            Beam indices of generated token id at each generation step. `torch.LongTensor` of shape
            `(batch_size*num_return_sequences, sequence_length)`.
        attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True`):
            Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
            `torch.FloatTensor` of shape `(batch_size*num_beams, num_heads, generated_length, sequence_length)`.
        hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True`):
            Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
            `torch.FloatTensor` of shape `(batch_size*num_beams*num_return_sequences, generated_length, hidden_size)`.
        past_key_values (`Cache`, *optional*, returned when `use_cache=True`):
            Returns the model cache, used to speed up decoding. Different models have a different cache format, check
            the model's documentation. Usually, a [`~cache_utils.Cache`] instance.
    """

    sequences: torch.LongTensor
    sequences_scores: torch.FloatTensor | None = None
    scores: tuple[torch.FloatTensor] | None = None
    logits: tuple[torch.FloatTensor] | None = None
    beam_indices: torch.LongTensor | None = None
    attentions: tuple[tuple[torch.FloatTensor]] | None = None
    hidden_states: tuple[tuple[torch.FloatTensor]] | None = None
    past_key_values: Cache | None = None


@dataclass
class GenerateBeamEncoderDecoderOutput(ModelOutput):
    """
    Outputs of encoder-decoder generation models, when using beam methods.

    Args:
        sequences (`torch.LongTensor` of shape `(batch_size*num_return_sequences, sequence_length)`):
            The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or shorter
            if all batches finished early due to the `eos_token_id`.
        sequences_scores (`torch.FloatTensor` of shape `(batch_size*num_return_sequences)`, *optional*, returned when `output_scores=True`):
            Final beam scores of the generated `sequences`.
        scores (`tuple(torch.FloatTensor)` *optional*, returned when `output_scores=True`):
            Beam transition scores for each vocabulary token at each generation step. Beam transition scores consisting
            of log probabilities of tokens conditioned on log softmax of previously generated tokens in this beam.
            Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for each generated token),
            with each tensor of shape `(batch_size*num_beams, config.vocab_size)`.
        logits (`tuple(torch.FloatTensor)` *optional*, returned when `output_logits=True`):
            Unprocessed prediction scores of the language modeling head (scores for each vocabulary token before SoftMax)
            at each generation step. Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for
            each generated token), with each tensor of shape `(batch_size*num_beams, config.vocab_size)`.
        beam_indices (`torch.LongTensor`, *optional*, returned when `output_scores=True`):
            Beam indices of generated token id at each generation step. `torch.LongTensor` of shape
            `(batch_size*num_return_sequences, sequence_length)`.
        encoder_attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True`):
            Tuple of `torch.FloatTensor` (one for each layer of the decoder) of shape `(batch_size, num_heads,
            sequence_length, sequence_length)`.
        encoder_hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True`):
            Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of
            shape `(batch_size*num_beams*num_return_sequences, sequence_length, hidden_size)`.
        decoder_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True`):
            Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
            `torch.FloatTensor` of shape `(batch_size*num_beams*num_return_sequences, num_heads, generated_length,
            sequence_length)`.
        cross_attentions (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_attentions=True`):
            Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
            `torch.FloatTensor` of shape `(batch_size, num_heads, generated_length, sequence_length)`.
        decoder_hidden_states (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `output_hidden_states=True`):
            Tuple (one element for each generated token) of tuples (one element for each layer of the decoder) of
            `torch.FloatTensor` of shape `(batch_size*num_beams*num_return_sequences, generated_length, hidden_size)`.
        past_key_values (`Cache`, *optional*, returned when `use_cache=True`):
            Returns the model cache, used to speed up decoding. Different models have a different cache format, check
            the model's documentation. Usually, a [`~cache_utils.Cache`] instance.
    """

    sequences: torch.LongTensor
    sequences_scores: torch.FloatTensor | None = None
    scores: tuple[torch.FloatTensor] | None = None
    logits: tuple[torch.FloatTensor] | None = None
    beam_indices: torch.LongTensor | None = None
    encoder_attentions: tuple[torch.FloatTensor] | None = None
    encoder_hidden_states: tuple[torch.FloatTensor] | None = None
    decoder_attentions: tuple[tuple[torch.FloatTensor]] | None = None
    cross_attentions: tuple[tuple[torch.FloatTensor]] | None = None
    decoder_hidden_states: tuple[tuple[torch.FloatTensor]] | None = None
    past_key_values: Cache | None = None


# Typing shortcuts
GenerateNonBeamOutput = GenerateDecoderOnlyOutput | GenerateEncoderDecoderOutput
GenerateBeamOutput = GenerateBeamDecoderOnlyOutput | GenerateBeamEncoderDecoderOutput
GenerateOutput = GenerateNonBeamOutput | GenerateBeamOutput


class GenerationMixin(ContinuousMixin):
    """
    A class containing all functions for auto-regressive text generation, to be used as a mixin in model classes.
    Inheriting from this class causes the model to have special generation-related behavior, such as loading a
    `GenerationConfig` at initialization time or ensuring `generate`-related tests are run in `transformers` CI.

    A model class should inherit from `GenerationMixin` to enable calling methods like `generate`, or when it
    has defined a custom `generate` method that relies on `GenerationMixin`, directly or indirectly, which
    approximately shares the same interface to public methods like `generate`. Three examples:
        - `LlamaForCausalLM` should inherit from `GenerationMixin` to enable calling `generate` and other public
            methods in the mixin;
        - `BlipForQuestionAnswering` has a custom `generate` method that approximately shares the same interface as
           `GenerationMixin.generate` (it has a few extra arguments, and the same output). That function also calls
           `GenerationMixin.generate` indirectly, through an inner model. As such, `BlipForQuestionAnswering` should
           inherit from `GenerationMixin` to benefit from all generation-related automation in our codebase;
        - `BarkModel` has a custom `generate` method and one of its inner models calls `GenerationMixin.generate`.
            However, its `generate` does not share the same interface as `GenerationMixin.generate`. In this case,
            `BarkModel` should NOT inherit from `GenerationMixin`, as it breaks the `generate` interface.

    The class exposes [`~generation.GenerationMixin.generate`], which can be used for:
        - *greedy decoding* if `num_beams=1` and `do_sample=False`
        - *multinomial sampling* if `num_beams=1` and `do_sample=True`
        - *beam-search decoding* if `num_beams>1` and `do_sample=False`
        - *beam-search multinomial sampling* if `num_beams>1` and `do_sample=True`
        - *assisted decoding* if `assistant_model` or `prompt_lookup_num_tokens` is passed to `.generate()`

    To learn more about decoding strategies refer to the [text generation strategies guide](../generation_strategies).
    """

    # Should be overwritten by models that can generate non-text output
    output_modalities = ("text",)

    def adjust_generation_fn(
        self: "GenerativePreTrainedModel",
        generation_config,
        from_auto_class,
        from_pipeline,
        pretrained_model_name_or_path,
        cache_dir,
        force_download,
        proxies,
        local_files_only,
        token,
        revision,
        subfolder,
        trust_remote_code,
        **kwargs,
    ):
        if self.can_generate() and generation_config is not None:
            self.generation_config = self.generation_config.from_dict(generation_config.to_dict())
        elif self.can_generate() and pretrained_model_name_or_path is not None:
            repo_loading_kwargs = {
                "cache_dir": cache_dir,
                "force_download": force_download,
                "proxies": proxies,
                "local_files_only": local_files_only,
                "token": token,
                "revision": revision,
                "subfolder": subfolder,
                **kwargs,
            }
            # Load generation config
            try:
                self.generation_config = GenerationConfig.from_pretrained(
                    pretrained_model_name_or_path,
                    _from_auto=from_auto_class,
                    _from_pipeline=from_pipeline,
                    **repo_loading_kwargs,
                )
            except OSError:
                # `self` already has a generation config created from model config, but model config will
                # not contain any generation-specific params. These are popped at config's `__init__`.
                # Thus we have to load from `config.json` and create a generation config from it (for BART)
                logger.info(
                    "Generation config file not found, using a generation config created from the model config."
                )
                self.generation_config = GenerationConfig.from_pretrained(
                    pretrained_model_name_or_path,
                    config_file_name="config.json",
                    _from_auto=from_auto_class,
                    _from_pipeline=from_pipeline,
                    _from_model_config=True,
                    **repo_loading_kwargs,
                )

            # Load custom generate function if `pretrained_model_name_or_path` defines it (and override `generate`)
            if hasattr(self, "load_custom_generate") and trust_remote_code:
                try:
                    custom_generate = self.load_custom_generate(
                        pretrained_model_name_or_path, trust_remote_code=trust_remote_code, **repo_loading_kwargs
                    )
                    self.generate = functools.partial(custom_generate, model=self)
                except OSError:  # there is no custom generate function
                    pass

    def load_custom_generate(
        self,
        pretrained_model_name_or_path: str | os.PathLike | None = None,
        trust_remote_code: bool | None = None,
        **kwargs,
    ) -> Callable:
        """
        Loads and returns a custom generate function, given a model repo.

        Args:
            pretrained_model_name_or_path (`str` or `os.PathLike`):
                 Can be either:
                    - A string, the *model id* of a pretrained model hosted inside a model repo on huggingface.co.
                    - A path to a *directory* containing model weights saved using
                      [`~PreTrainedModel.save_pretrained`], e.g., `./my_model_directory/`.
            trust_remote_code (`bool`, *optional*):
                Whether or not to allow for custom models defined on the Hub in their own modeling files. This option
                should only be set to `True` for repositories you trust and in which you have read the code, as it will
                execute code present on the Hub on your local machine.
            **kwargs:
                Additional keyword arguments for remote code loading.

        Raises:
            OSError: If `pretrained_model_name_or_path` does not contain a `custom_generate` subdirectory.

        Returns:
            A callable that can be used to generate text.
        """
        # Fetches the generate.py file from the model repo. If it doesn't exist, a file in `.no_exist` cache directory
        # is created (preventing future hub requests), and an OSError is raised.
        try:
            module = get_cached_module_file(
                pretrained_model_name_or_path, module_file="custom_generate/generate.py", **kwargs
            )
        except OSError:
            raise OSError(
                f"`{pretrained_model_name_or_path}` does not contain a `custom_generate` subdirectory with a "
                "`generate.py` file, can't load the custom generate function."
            )

        # Loading a custom generate function executes the repository's `custom_generate/generate.py`
        # (via `get_class_in_module` below), so it is remote code and must be gated by
        # `trust_remote_code` -- including when it is loaded from a local directory. `from_pretrained`
        # likewise requires `trust_remote_code` for custom modeling code that lives in a local repo;
        # treating a local path as trusted here previously let `custom_generate/generate.py` run with
        # no opt-in.
        error_message = (
            f"The repository `{pretrained_model_name_or_path}` contains custom generation code that will override "
            "the default `generate` method."
        )
        resolve_trust_remote_code(
            trust_remote_code,
            pretrained_model_name_or_path,
            has_local_code=False,
            has_remote_code=True,
            error_message=error_message,
        )

        # Load the custom generate function
        check_python_requirements(
            pretrained_model_name_or_path, requirements_file="custom_generate/requirements.txt", **kwargs
        )
        custom_generate_function = get_class_in_module("generate", module)
        return custom_generate_function

    def prepare_inputs_for_generation(
        self: "GenerativePreTrainedModel",
        input_ids: torch.LongTensor,
        next_sequence_length: int | None = None,
        past_key_values: Cache | None = None,
        attention_mask: torch.LongTensor | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        is_first_iteration: bool | None = False,
        **kwargs,
    ):
        """
        Prepare the model inputs for generation. Notable steps include selecting the correct input key and cloning when appropriate,
        creating position_ids from the attention_mask when missing, slicing inputs and converting 2D attention masks to 4D for
        compilable caches, and finally forwarding all additional keyword arguments unchanged to the model's forward pass.

        See the forward pass in the model documentation for expected arguments (different models might have different
        requirements for e.g. `past_key_values`). This function should work as is for most LLMs.
        """
        # Instantiate output
        model_inputs = {}

        # 1. Prepare base model inputs
        input_ids_key = "decoder_input_ids" if self.config.is_encoder_decoder else "input_ids"
        # if `inputs_embeds` are passed, we only want to use them in the 1st generation step for every prompt.
        if not self.config.is_encoder_decoder and inputs_embeds is not None and is_first_iteration:
            model_inputs[input_ids_key] = None
            prompt_embeds = (
                inputs_embeds[:, -next_sequence_length:, :] if next_sequence_length is not None else inputs_embeds
            )
            model_inputs["inputs_embeds"] = prompt_embeds.clone(memory_format=torch.contiguous_format)
            batch_size, sequence_length = prompt_embeds.shape[:2]
        else:
            # `clone` calls in this function ensure a consistent stride. See #32227
            input_ids = input_ids[:, -next_sequence_length:] if next_sequence_length is not None else input_ids
            model_inputs[input_ids_key] = input_ids.clone(memory_format=torch.contiguous_format)
            batch_size, sequence_length = input_ids.shape[:2]  # we slice here as some models may have them 3D

        # 2. Add important inputs
        if past_key_values is not None:
            model_inputs["past_key_values"] = past_key_values
        position_ids_key = "decoder_position_ids" if self.config.is_encoder_decoder else "position_ids"
        if (position_ids := kwargs.pop(position_ids_key, None)) is not None:
            model_inputs[position_ids_key] = position_ids
        if (token_type_ids := kwargs.pop("token_type_ids", None)) is not None:
            model_inputs["token_type_ids"] = token_type_ids

        # 3. Slice model inputs if it's an input that should have the same length as `input_ids`
        for model_input_name in [position_ids_key, "token_type_ids", "mm_token_type_ids"]:
            model_input = model_inputs.get(model_input_name)
            if model_input is not None and model_input.shape[-1] != sequence_length:
                # Input can be 2D or 3D, and we always slice on `seq-length` (last dim)
                model_input = model_input[..., -sequence_length:].clone(memory_format=torch.contiguous_format)
                model_inputs[model_input_name] = model_input

        # 4. Create 4D attention mask is we are using a compilable cache (important for performant compiled forward
        # pass)
        encoder_attention_mask = attention_mask if self.config.is_encoder_decoder else None
        attention_mask_key = "decoder_attention_mask" if self.config.is_encoder_decoder else "attention_mask"
        attention_mask = (
            kwargs.pop("decoder_attention_mask", None) if self.config.is_encoder_decoder else attention_mask
        )
        if (
            isinstance(past_key_values, Cache)
            and past_key_values.is_compileable
            and attention_mask is not None
            and attention_mask.ndim == 2
        ):
            # Some models may overwrite the general one
            causal_mask_creation_function = getattr(self, "create_masks_for_generate", create_masks_for_generate)
            attention_mask = causal_mask_creation_function(
                config=self.config,
                # we only need batch size, seq_length, dtype and device here - so we pass a 0-sized tensor with only the metadata
                inputs_embeds=torch.empty((batch_size, sequence_length, 0), dtype=self.dtype, device=input_ids.device),
                attention_mask=attention_mask,
                past_key_values=model_inputs.get("past_key_values"),
                position_ids=model_inputs.get(position_ids_key),
                block_sequence_ids=model_inputs.get("block_sequence_ids"),
                # The following kwargs are not used in the main function - only on a few models with overloaded `create_masks_for_generate`
                token_type_ids=model_inputs.get("token_type_ids"),
                mm_token_type_ids=model_inputs.get("mm_token_type_ids"),
                is_first_iteration=is_first_iteration,
            )

        if attention_mask is not None:
            model_inputs[attention_mask_key] = attention_mask

        if encoder_attention_mask is not None:
            model_inputs["attention_mask"] = encoder_attention_mask

        # 5. Forward ALL kwargs that are uninitialized, e.g. `use_cache` (except a few exceptions)
        kwargs_to_avoid_forwarding = ("labels", "next_sequence_length")
        for key, value in kwargs.items():
            if key not in model_inputs and key not in kwargs_to_avoid_forwarding:
                model_inputs[key] = value

        # BC for remote code models only: create `cache_position` on the fly here, as we don't want to maintain them in kwargs
        # between `forward`s
        if self.is_remote_code() and "cache_position" in set(inspect.signature(self.forward).parameters):
            logger.warning_once(
                "The remote code model you are currently using seems to expect `cache_position`. This arg has been "
                "removed from the Transformers library, and will stop being created in `generate` even for remote code models "
                "in a future release. Please open a PR on the remote code hub repo to remove any usage of `cache_position`."
            )
            past_seen_tokens = past_key_values.get_seq_length() if past_key_values is not None else 0
            cache_position = torch.arange(sequence_length, device=input_ids.device) + past_seen_tokens
            model_inputs["cache_position"] = cache_position

        # 6. Move the tensors the forward consumes onto the model device, right before the call.
        # It lets the caller intentionally keep inputs on a different device (e.g. Neuron/TPU) so
        # the generation loop's growing-tensor bookkeeping stays off-device.
        input_tensor = model_inputs.get("inputs_embeds", model_inputs[input_ids_key])  # input_ids is None for embeds
        if self.device.type != "meta" and input_tensor is not None and input_tensor.device != self.device:
            for key, value in model_inputs.items():
                if isinstance(value, torch.Tensor):
                    model_inputs[key] = value.to(self.device)

        return model_inputs

    def _prepare_model_inputs(
        self: "GenerativePreTrainedModel",
        inputs: torch.Tensor | None,
        bos_token_id: torch.Tensor | None,
        model_kwargs: dict[str, torch.Tensor],
    ) -> tuple[torch.Tensor, str | None, dict[str, torch.Tensor]]:
        """
        This function extracts the model-specific `inputs` for generation.
        """
        # 1. retrieve all kwargs that are non-None or non-model input related.
        # some encoder-decoder models have different names for model and encoder
        if (
            self.config.is_encoder_decoder
            and hasattr(self, "encoder")
            and self.encoder.main_input_name != self.main_input_name
        ):
            input_name = self.encoder.main_input_name
        else:
            input_name = self.main_input_name

        # 2. check whether model_input_name is passed as kwarg
        # if yes and `inputs` is None use kwarg inputs
        inputs_kwarg = model_kwargs.pop(input_name, None)
        if inputs_kwarg is not None and inputs is not None:
            raise ValueError(
                f"`inputs`: {inputs}` were passed alongside {input_name} which is not allowed. "
                f"Make sure to either pass {inputs} or {input_name}=..."
            )
        elif inputs_kwarg is not None:
            inputs = inputs_kwarg

        # 3. In the presence of `inputs_embeds` for text models:
        # - decoder-only models should complain if the user attempts to pass `inputs_embeds`, but the model
        # doesn't have its forwarding implemented. `inputs_embeds` is kept in `model_kwargs` and can coexist with
        # input_ids (`inputs_embeds` will be used in the 1st generation step, as opposed to `input_ids`)
        # - encoder-decoder models should complain if the user attempts to pass `inputs_embeds` and `input_ids`, and
        # pull the former to inputs. It will be used in place of `input_ids` to get the encoder hidden states.
        if input_name == "input_ids" and "inputs_embeds" in model_kwargs:
            if model_kwargs["inputs_embeds"] is None:
                model_kwargs.pop("inputs_embeds")
            elif not self.config.is_encoder_decoder:
                has_inputs_embeds_forwarding = "inputs_embeds" in set(
                    inspect.signature(self.prepare_inputs_for_generation).parameters.keys()
                )
                if not has_inputs_embeds_forwarding:
                    raise ValueError(
                        f"You passed `inputs_embeds` to `.generate()`, but the model class {self.__class__.__name__} "
                        "doesn't have its forwarding implemented. See the GPT2 implementation for an example "
                        "(https://github.com/huggingface/transformers/pull/21405), and feel free to open a PR with it!"
                    )
                # In this case, `input_ids` is moved to the `model_kwargs`, so a few automations (like the creation of
                # the attention mask) can rely on the actual model input.
                model_kwargs["input_ids"] = self._maybe_initialize_input_ids_for_generation(
                    inputs, bos_token_id, model_kwargs=model_kwargs
                )
                inputs, input_name = model_kwargs["inputs_embeds"], "inputs_embeds"
            else:
                if inputs is not None:
                    raise ValueError("You passed `inputs_embeds` and `input_ids` to `.generate()`. Please pick one.")
                inputs, input_name = model_kwargs["inputs_embeds"], "inputs_embeds"

        # 4. if `inputs` is still None, try to create `input_ids` from BOS token
        inputs = self._maybe_initialize_input_ids_for_generation(inputs, bos_token_id, model_kwargs)
        return inputs, input_name, model_kwargs

    def _maybe_initialize_input_ids_for_generation(
        self: "GenerativePreTrainedModel",
        inputs: torch.Tensor | None,
        bos_token_id: torch.Tensor | None,
        model_kwargs: dict[str, torch.Tensor],
    ) -> torch.LongTensor:
        """Initializes input ids for generation, if necessary."""
        if inputs is not None:
            return inputs

        encoder_outputs = model_kwargs.get("encoder_outputs")
        last_hidden_state = getattr(encoder_outputs, "last_hidden_state", None)
        if self.config.is_encoder_decoder and last_hidden_state is not None:
            # make dummy input_ids with value -100, as a sanity check ensuring that they won't be used for encoding
            shape = last_hidden_state.size()[:-1]
            return torch.ones(shape, dtype=torch.long, device=self.device) * -100

        # If there is some tensor in `model_kwargs`, we can infer the batch size from it. This is helpful with
        # soft-prompting or in multimodal implementations built on top of decoder-only language models.
        batch_size = 1
        for value in model_kwargs.values():
            if isinstance(value, torch.Tensor):
                batch_size = value.shape[0]
                break

        if "inputs_embeds" in model_kwargs:
            return torch.ones(
                (batch_size, 0),
                dtype=torch.long,
                # Use the device of the existing tensor to avoid any potential `meta` device issue, which is likely
                # linked to the offloading behavior (keeping it on meta device). See PR #44848. Previously, it used
                # `self.device`.
                device=self.device if self.device.type != "meta" else model_kwargs["inputs_embeds"].device,
            )

        if bos_token_id is None:
            raise ValueError("`bos_token_id` has to be defined when no `input_ids` are provided.")

        return torch.ones((batch_size, 1), dtype=torch.long, device=self.device) * bos_token_id

    def _prepare_position_ids_for_generation(self, inputs_tensor, model_kwargs):
        """
        Tries to infer position ids given attention mask and past kv cache length. All instances when
        `position_ids=None` should call this method.
        """
        # `input_ids` may be present in the model kwargs, instead of being the main input (e.g. multimodal model)
        if "input_ids" in model_kwargs and model_kwargs["input_ids"].shape[1] > 0:
            inputs_tensor = model_kwargs["input_ids"]

        seq_length = inputs_tensor.shape[1]

        if (attention_mask := model_kwargs.get("attention_mask")) is not None:
            position_ids = attention_mask.long().cumsum(-1) - 1
            # We need this as otherwise padding tokens appear as -1 in position
            position_ids = position_ids.masked_fill(attention_mask == 0, 0)
        else:
            past_length = 0
            if (cache := model_kwargs.get("past_key_values")) is not None:
                past_length = cache.get_seq_length()

            position_ids = torch.arange(seq_length + past_length, dtype=torch.long, device=inputs_tensor.device)
            position_ids = position_ids.unsqueeze(0)
        return position_ids

    def _prepare_attention_mask_for_generation(
        self,
        inputs_tensor: torch.Tensor,
        generation_config: GenerationConfig,
        model_kwargs: dict[str, Any],
    ) -> torch.LongTensor:
        pad_token_id = generation_config._pad_token_tensor
        eos_token_id = generation_config._eos_token_tensor

        # `input_ids` may be present in the model kwargs, instead of being the main input (e.g. multimodal model)
        if "input_ids" in model_kwargs and model_kwargs["input_ids"].shape[1] > 0:
            inputs_tensor = model_kwargs["input_ids"]

        # No information for attention mask inference -> return default attention mask
        default_attention_mask = torch.ones(inputs_tensor.shape[:2], dtype=torch.long, device=inputs_tensor.device)
        if pad_token_id is None:
            return default_attention_mask

        is_input_ids = len(inputs_tensor.shape) == 2 and inputs_tensor.dtype in [torch.int, torch.long]
        if not is_input_ids:
            return default_attention_mask

        is_pad_token_in_inputs = (pad_token_id is not None) and (torch.isin(inputs_tensor, pad_token_id).any())
        is_pad_token_not_equal_to_eos_token_id = (eos_token_id is None) or ~(
            torch.isin(eos_token_id, pad_token_id).any()
        )
        can_infer_attention_mask = is_pad_token_in_inputs * is_pad_token_not_equal_to_eos_token_id
        attention_mask_from_padding = inputs_tensor.ne(pad_token_id).long()

        attention_mask = (
            attention_mask_from_padding * can_infer_attention_mask + default_attention_mask * ~can_infer_attention_mask
        )
        return attention_mask

    def _prepare_encoder_decoder_kwargs_for_generation(
        self: "GenerativePreTrainedModel",
        inputs_tensor: torch.Tensor,
        model_kwargs,
        model_input_name: str | None,
        generation_config: GenerationConfig,
    ) -> dict[str, Any]:
        # 1. get encoder
        encoder = self.get_encoder()
        # Compatibility with Accelerate big model inference: we need the encoder to outputs stuff on the same device
        # as the inputs.
        if hasattr(self, "hf_device_map"):
            if hasattr(encoder, "_hf_hook"):
                encoder._hf_hook.io_same_device = True
            else:
                add_hook_to_module(encoder, AlignDevicesHook(io_same_device=True))

        # 2. Prepare encoder args and encoder kwargs from model kwargs and generation config.
        irrelevant_prefix = ["decoder_", "cross_attn", "use_cache", "past_key_values", "cache_params"]
        encoder_kwargs = {
            argument: value
            for argument, value in model_kwargs.items()
            if not any(argument.startswith(p) for p in irrelevant_prefix)
        }
        encoder_signature = set(inspect.signature(encoder.forward).parameters)
        encoder_accepts_wildcard = "kwargs" in encoder_signature or "model_kwargs" in encoder_signature
        if not encoder_accepts_wildcard:
            encoder_kwargs = {
                argument: value for argument, value in encoder_kwargs.items() if argument in encoder_signature
            }
        encoder_kwargs["output_attentions"] = generation_config.output_attentions
        encoder_kwargs["output_hidden_states"] = generation_config.output_hidden_states

        # 3. make sure that encoder returns `ModelOutput`
        model_input_name = model_input_name if model_input_name is not None else self.main_input_name
        encoder_kwargs["return_dict"] = True
        encoder_kwargs[model_input_name] = inputs_tensor
        model_kwargs["encoder_outputs"]: ModelOutput = encoder(**encoder_kwargs)

        return model_kwargs

    def _prepare_decoder_input_ids_for_generation(
        self: "GenerativePreTrainedModel",
        batch_size: int,
        model_input_name: str,
        model_kwargs: dict[str, torch.Tensor],
        decoder_start_token_id: torch.Tensor,
        device: torch.device | None = None,
    ) -> tuple[torch.LongTensor, dict[str, torch.Tensor]]:
        """Prepares `decoder_input_ids` for generation with encoder-decoder models"""
        # 1. Check whether the user has defined `decoder_input_ids` manually. To facilitate in terms of input naming,
        # we also allow the user to pass it under `input_ids`, if the encoder does not use it as the main input.
        if model_kwargs is not None and "decoder_input_ids" in model_kwargs:
            decoder_input_ids = model_kwargs.pop("decoder_input_ids")
        elif "input_ids" in model_kwargs and model_input_name != "input_ids":
            decoder_input_ids = model_kwargs.pop("input_ids")
        else:
            decoder_input_ids = None

        # 2. `decoder_start_token_id` must have shape (batch_size, 1)
        if device is None:
            device = self.device
        if decoder_start_token_id.ndim == 1:
            if decoder_start_token_id.shape[0] != batch_size:
                raise ValueError(
                    f"`decoder_start_token_id` expected to have length {batch_size} but got {decoder_start_token_id.shape[0]}"
                )
            decoder_start_token_id = decoder_start_token_id.view(-1, 1)
        else:
            decoder_start_token_id = (
                torch.ones((batch_size, 1), dtype=torch.long, device=device) * decoder_start_token_id
            )

        # 3. Encoder-decoder models expect the `decoder_input_ids` to start with a special token. Let's ensure that.
        # no user input -> use decoder_start_token_id as decoder_input_ids
        if decoder_input_ids is None:
            decoder_input_ids = decoder_start_token_id
        # exception: Donut checkpoints have task-specific decoder starts and don't expect a BOS token. Note that the
        # original checkpoints can't be detected through `self.__class__.__name__.lower()`, needing custom logic.
        # See: https://github.com/huggingface/transformers/pull/31470
        elif "donut" in self.__class__.__name__.lower() or (
            self.config.model_type == "vision-encoder-decoder" and "donut" in self.config.encoder.model_type.lower()
        ):
            pass
        elif self.config.model_type == "whisper":
            pass
        # user input but doesn't start with decoder_start_token_id -> prepend decoder_start_token_id (and adjust
        # decoder_attention_mask if provided)
        elif (decoder_input_ids[:, 0] != decoder_start_token_id[:, 0]).all().item():
            decoder_input_ids = torch.cat([decoder_start_token_id, decoder_input_ids], dim=-1)
            if "decoder_attention_mask" in model_kwargs:
                decoder_attention_mask = model_kwargs["decoder_attention_mask"]
                decoder_attention_mask = torch.cat(
                    (torch.ones_like(decoder_attention_mask)[:, :1], decoder_attention_mask),
                    dim=-1,
                )
                model_kwargs["decoder_attention_mask"] = decoder_attention_mask

        return decoder_input_ids, model_kwargs

    @staticmethod
    def _expand_inputs_for_generation(
        expand_size: int = 1,
        is_encoder_decoder: bool = False,
        input_ids: torch.LongTensor | None = None,
        **model_kwargs,
    ) -> tuple[torch.LongTensor, dict[str, Any]]:
        """Expands tensors from [batch_size, ...] to [batch_size * expand_size, ...]"""
        # Do not call torch.repeat_interleave if expand_size is 1 because it clones
        # the input tensor and thus requires more memory although no change is applied
        if expand_size == 1:
            return input_ids, model_kwargs

        def _expand_dict_for_generation(dict_to_expand):
            for key in dict_to_expand:
                if dict_to_expand[key] is not None and isinstance(dict_to_expand[key], torch.Tensor):
                    dict_to_expand[key] = dict_to_expand[key].repeat_interleave(expand_size, dim=0)
            return dict_to_expand

        if input_ids is not None:
            input_ids = input_ids.repeat_interleave(expand_size, dim=0)

        model_kwargs = _expand_dict_for_generation(model_kwargs)

        if is_encoder_decoder:
            if model_kwargs.get("encoder_outputs") is None:
                raise ValueError("If `is_encoder_decoder` is True, make sure that `encoder_outputs` is defined.")
            model_kwargs["encoder_outputs"] = _expand_dict_for_generation(model_kwargs["encoder_outputs"])

        return input_ids, model_kwargs

    def _update_model_kwargs_for_generation(
        self,
        outputs: ModelOutput,
        model_kwargs: dict[str, Any],
        is_encoder_decoder: bool = False,
        num_new_tokens: int = 1,
    ) -> dict[str, Any]:
        """
        Update the model kwargs to account for the `num_new_tokens` new tokens that were just generated.
        That is, update the `attention_mask`, `position_ids`, and `token_type_ids` to account for the
        new tokens of the total sequence.
        Note that this function never slices inputs, this is performed in `prepare_inputs_for_generation`.
        """
        # update past_key_values keeping its naming used in model code
        for possible_cache_name in ALL_CACHE_NAMES:
            if possible_cache_name in outputs:
                # TODO (joao): remove output/input mismatch when these old models (xlnet, reformer) are deprecated
                if possible_cache_name in ("past_buckets_states", "mems"):
                    cache_name = "past_key_values"
                else:
                    cache_name = possible_cache_name
                model_kwargs[cache_name] = getattr(outputs, possible_cache_name)
                break

        # update token_type_ids with last value
        if (token_type_ids := model_kwargs.get("token_type_ids")) is not None:
            model_kwargs["token_type_ids"] = torch.cat([token_type_ids, token_type_ids[:, -num_new_tokens:]], dim=-1)

        # update mm_token_type_ids with zeros (only-text)
        if (mm_token_type_ids := model_kwargs.get("mm_token_type_ids")) is not None:
            model_kwargs["mm_token_type_ids"] = torch.cat(
                [mm_token_type_ids, mm_token_type_ids.new_zeros((mm_token_type_ids.shape[0], num_new_tokens))], dim=-1
            )

        # Position ids (2D or 3D sometimes)
        position_ids_key = "position_ids" if not is_encoder_decoder else "decoder_position_ids"
        if (position_ids := model_kwargs.get(position_ids_key)) is not None:
            # We want to expand to the same number of dims which is not always the same
            required_dim = [1] * (position_ids.dim() - 1) + [-1]
            next_position_ids = (
                torch.arange(num_new_tokens, dtype=position_ids.dtype, device=position_ids.device).view(*required_dim)
                + position_ids[..., -1:]
                + 1
            )
            next_position_ids = torch.cat([position_ids, next_position_ids], dim=-1)
            model_kwargs[position_ids_key] = next_position_ids

        # 2D attention mask (always 2D here)
        attention_mask_key = "attention_mask" if not is_encoder_decoder else "decoder_attention_mask"
        if (attention_mask := model_kwargs.get(attention_mask_key)) is not None:
            model_kwargs[attention_mask_key] = torch.cat(
                [attention_mask, attention_mask.new_ones((attention_mask.shape[0], num_new_tokens))], dim=-1
            )

        return model_kwargs

    def _get_candidate_generator(
        self: "GenerativePreTrainedModel",
        generation_config: GenerationConfig,
        input_ids: torch.LongTensor,
        inputs_tensor: torch.Tensor,
        logits_processor: LogitsProcessorList,
        model_kwargs: dict[str, Any],
        assistant_model: Optional["PreTrainedModel"] = None,
        target_tokenizer: Optional["PreTrainedTokenizerBase"] = None,
        assistant_tokenizer: Optional["PreTrainedTokenizerBase"] = None,
    ) -> CandidateGenerator:
        """
        Returns the candidate generator to be used in `assisted_generation`
        """
        different_tokenizers = all(v is not None for v in (assistant_model, target_tokenizer, assistant_tokenizer))

        if generation_config.assistant_early_exit is not None:
            candidate_generator = EarlyExitCandidateGenerator(
                input_ids=input_ids,
                assistant_model=self,
                generation_config=generation_config,
                model_kwargs=model_kwargs,
                inputs_tensor=inputs_tensor,
                logits_processor=logits_processor,
            )
        elif generation_config.prompt_lookup_num_tokens is not None:
            candidate_generator = PromptLookupCandidateGenerator(
                eos_token_id=generation_config._eos_token_tensor,
                num_output_tokens=generation_config.prompt_lookup_num_tokens,
                max_matching_ngram_size=generation_config.max_matching_ngram_size or 2,
                max_length=generation_config.max_length,
                logits_processor=logits_processor,
                vocab_size=self.config.get_text_config().vocab_size,
            )
        # SinglePositionMultiTokenCandidateGenerator requires a target model that can provide, and an assistant model that
        # can work from a shared_kv_states dictionary. Currently, the only models that can provide this are Gemma 3n and
        # Gemma 4, and the only model that can work from it is a Gemma 4 Assistant
        elif assistant_model is not None and assistant_model.__class__.__name__.startswith(
            ("Gemma4Assistant", "Gemma4UnifiedAssistant")
        ):
            if not self.__class__.__name__.startswith(("Gemma4", "Gemma3n")):
                raise ValueError(
                    f"Expected class name to start with Gemma4 or Gemma3n. Got {self.__class__.__name__}."
                    " Gemma4Assistant models require a target model that provides a shared_kv_states dictionary."
                    " Currently, only Gemma4 and Gemma3n provide a shared_kv_states dictionary."
                )

            candidate_generator = SinglePositionMultiTokenCandidateGenerator(
                input_ids=input_ids,
                assistant_model=assistant_model,
                target_model_input_embeddings=self.get_input_embeddings(),
                generation_config=generation_config,
                model_kwargs=model_kwargs,
                inputs_tensor=inputs_tensor,
                logits_processor=logits_processor,
            )
        elif different_tokenizers:
            assistant_model = cast("PreTrainedModel", assistant_model)
            target_tokenizer = cast("PreTrainedTokenizerBase", target_tokenizer)
            assistant_tokenizer = cast("PreTrainedTokenizerBase", assistant_tokenizer)
            if generation_config.do_sample is True:
                atm_translator = AssistantVocabTranslatorCache.get_translator(
                    target_tokenizer,
                    assistant_tokenizer,
                    self.config.get_text_config().vocab_size,
                    assistant_model=assistant_model,
                    assistant_prune_lm_head=True,  # prune LM head of assistant model
                )
                # Since we prune the LM head, we cannot use the repetition penalty on the assistant model due to mismatches between token ids and logits index
                assistant_model.generation_config.repetition_penalty = None
                candidate_generator = UniversalSpeculativeDecodingGenerator(
                    input_ids=input_ids,
                    assistant_model=assistant_model,
                    generation_config=generation_config,
                    model_kwargs=model_kwargs,
                    inputs_tensor=inputs_tensor,
                    logits_processor=logits_processor,
                    target_tokenizer=target_tokenizer,
                    assistant_tokenizer=assistant_tokenizer,
                    atm_translator=atm_translator,
                )
            elif generation_config.do_sample is False:
                candidate_generator = AssistedCandidateGeneratorDifferentTokenizers(
                    input_ids=input_ids,
                    assistant_model=assistant_model,
                    generation_config=generation_config,
                    model_kwargs=model_kwargs,
                    inputs_tensor=inputs_tensor,
                    logits_processor=logits_processor,
                    target_tokenizer=target_tokenizer,
                    assistant_tokenizer=assistant_tokenizer,
                )
            else:
                raise ValueError(
                    f"Invalid value for `do_sample`: expected a boolean, got {type(generation_config.do_sample).__name__}"
                )
        else:
            candidate_generator = AssistedCandidateGenerator(
                input_ids=input_ids,
                assistant_model=assistant_model,
                generation_config=generation_config,
                model_kwargs=model_kwargs,
                inputs_tensor=inputs_tensor,
                logits_processor=logits_processor,
            )
        return candidate_generator

    def _get_logits_processor(
        self: "GenerativePreTrainedModel",
        generation_config: GenerationConfig,
        input_ids_seq_length: int | None = None,
        encoder_input_ids: torch.LongTensor | None = None,
        prefix_allowed_tokens_fn: Callable[[int, torch.Tensor], list[int]] | None = None,
        logits_processor: LogitsProcessorList | None = None,
        device: str | None = None,
        model_kwargs: dict[str, Any] | None = None,
        negative_prompt_ids: torch.Tensor | None = None,
        negative_prompt_attention_mask: torch.Tensor | None = None,
    ) -> LogitsProcessorList:
        """
        This class returns a [`LogitsProcessorList`] list object that contains all relevant [`LogitsProcessor`]
        instances used to modify the scores of the language model head.
        """
        # instantiate processors list
        processors = LogitsProcessorList()
        if logits_processor is None:
            logits_processor = []

        if generation_config.guidance_scale is not None and generation_config.guidance_scale != 1:
            processors.append(
                UnbatchedClassifierFreeGuidanceLogitsProcessor(
                    generation_config.guidance_scale,
                    self,
                    unconditional_ids=negative_prompt_ids,
                    unconditional_attention_mask=negative_prompt_attention_mask,
                    use_cache=generation_config.use_cache,
                )
            )
        if generation_config.sequence_bias is not None:
            processors.append(SequenceBiasLogitsProcessor(sequence_bias=generation_config.sequence_bias))

        if (
            generation_config.encoder_repetition_penalty is not None
            and generation_config.encoder_repetition_penalty != 1.0
        ):
            if encoder_input_ids is not None and len(encoder_input_ids.shape) == 2:
                processors.append(
                    EncoderRepetitionPenaltyLogitsProcessor(
                        penalty=generation_config.encoder_repetition_penalty,
                        encoder_input_ids=encoder_input_ids,
                    )
                )
            else:
                warnings.warn(
                    "Passing `encoder_repetition_penalty` requires some form of `input_ids` to be passed to "
                    "`generate`, ignoring the argument.",
                    UserWarning,
                )
        if generation_config.repetition_penalty is not None and generation_config.repetition_penalty != 1.0:
            processors.append(RepetitionPenaltyLogitsProcessor(penalty=generation_config.repetition_penalty))
            if not self.config.is_encoder_decoder and (input_ids_seq_length is None or input_ids_seq_length == 0):
                warnings.warn(
                    "Passing `repetition_penalty` with `inputs_embeds` and without `input_ids` to `generate` will "
                    "apply the penalty only to newly generated tokens, not to the prompt.",
                    UserWarning,
                )
        if generation_config.no_repeat_ngram_size is not None and generation_config.no_repeat_ngram_size > 0:
            processors.append(NoRepeatNGramLogitsProcessor(generation_config.no_repeat_ngram_size))
            if not self.config.is_encoder_decoder and (input_ids_seq_length is None or input_ids_seq_length == 0):
                warnings.warn(
                    "Passing `no_repeat_ngram_size` with `inputs_embeds` and without `input_ids` to `generate` will "
                    "apply n-gram constraints only to newly generated tokens, not to the prompt.",
                    UserWarning,
                )
        if (
            generation_config.encoder_no_repeat_ngram_size is not None
            and generation_config.encoder_no_repeat_ngram_size > 0
        ):
            if encoder_input_ids is not None and len(encoder_input_ids.shape) == 2:
                processors.append(
                    EncoderNoRepeatNGramLogitsProcessor(
                        generation_config.encoder_no_repeat_ngram_size,
                        encoder_input_ids,
                    )
                )
            else:
                warnings.warn(
                    "Passing `encoder_no_repeat_ngram_size` requires some form of `input_ids` to be passed to "
                    "`generate`, ignoring the argument.",
                    UserWarning,
                )
        if generation_config.bad_words_ids is not None:
            processors.append(
                NoBadWordsLogitsProcessor(
                    generation_config.bad_words_ids,
                    generation_config._eos_token_tensor,
                )
            )
        if (
            generation_config.min_length is not None
            and getattr(generation_config, "_eos_token_tensor", None) is not None
            and generation_config.min_length > 0
        ):
            processors.append(
                MinLengthLogitsProcessor(
                    generation_config.min_length,
                    generation_config._eos_token_tensor,
                    device=device,
                )
            )
        if (
            generation_config.min_new_tokens is not None
            and getattr(generation_config, "_eos_token_tensor", None) is not None
            and generation_config.min_new_tokens > 0
        ):
            processors.append(
                MinNewTokensLengthLogitsProcessor(
                    input_ids_seq_length,
                    generation_config.min_new_tokens,
                    generation_config._eos_token_tensor,
                    device=device,
                )
            )
        if prefix_allowed_tokens_fn is not None:
            processors.append(
                PrefixConstrainedLogitsProcessor(
                    prefix_allowed_tokens_fn,
                    generation_config.num_beams,
                )
            )
        if generation_config.forced_bos_token_id is not None:
            processors.append(
                ForcedBOSTokenLogitsProcessor(
                    generation_config.forced_bos_token_id,
                )
            )
        if generation_config.forced_eos_token_id is not None:
            processors.append(
                ForcedEOSTokenLogitsProcessor(
                    generation_config.max_length,
                    generation_config.forced_eos_token_id,
                    device=device,
                )
            )
        if generation_config.remove_invalid_values is True:
            processors.append(InfNanRemoveLogitsProcessor())
        if generation_config.exponential_decay_length_penalty is not None:
            processors.append(
                ExponentialDecayLengthPenalty(
                    generation_config.exponential_decay_length_penalty,
                    generation_config._eos_token_tensor,
                    input_ids_seq_length,
                )
            )
        if generation_config.suppress_tokens is not None:
            processors.append(
                SuppressTokensLogitsProcessor(
                    generation_config.suppress_tokens,
                    device=device,
                )
            )
        if generation_config.begin_suppress_tokens is not None:
            begin_index = input_ids_seq_length
            begin_index = (
                begin_index
                if (input_ids_seq_length > 1 or generation_config.forced_bos_token_id is None)
                else begin_index + 1
            )
            processors.append(
                SuppressTokensAtBeginLogitsProcessor(
                    generation_config.begin_suppress_tokens,
                    begin_index,
                    device=device,
                )
            )

        # TODO (joao): find a strategy to specify the order of the processors
        processors = self._merge_criteria_processor_list(processors, logits_processor)

        # Processors previously known as `LogitsWarpers`, only applied with sampling strategies
        if generation_config.do_sample:
            # In beam methods, we need to keep at least one non-eos token to explore continuations that might have a
            # better score (i.e. keep len(list(generation_config._eos_token_tensor)) + 1)
            if generation_config.num_beams is not None and generation_config.num_beams > 1:
                if isinstance(generation_config._eos_token_tensor, list):
                    min_tokens_to_keep = len(generation_config._eos_token_tensor) + 1
                elif isinstance(generation_config._eos_token_tensor, torch.Tensor):
                    min_tokens_to_keep = generation_config._eos_token_tensor.shape[0] + 1
                else:
                    min_tokens_to_keep = 2
            else:
                min_tokens_to_keep = 1

            # the following idea is largely copied from this PR: https://github.com/huggingface/transformers/pull/5420/files
            # all samplers can be found in `generation_utils_samplers.py`
            if generation_config.temperature is not None and generation_config.temperature != 1.0:
                processors.append(TemperatureLogitsWarper(generation_config.temperature))
            if generation_config.top_h is not None:
                processors.append(TopHLogitsWarper(top_h=generation_config.top_h))
            if generation_config.top_k is not None and generation_config.top_k != 0:
                processors.append(
                    TopKLogitsWarper(top_k=generation_config.top_k, min_tokens_to_keep=min_tokens_to_keep)
                )
            if generation_config.top_p is not None and generation_config.top_p < 1.0:
                processors.append(
                    TopPLogitsWarper(top_p=generation_config.top_p, min_tokens_to_keep=min_tokens_to_keep)
                )
            if generation_config.min_p is not None:
                # Applied after temperature scaling (see https://github.com/ggerganov/llama.cpp/pull/3841#issuecomment-2073826084)
                processors.append(
                    MinPLogitsWarper(min_p=generation_config.min_p, min_tokens_to_keep=min_tokens_to_keep)
                )
            if generation_config.typical_p is not None and generation_config.typical_p < 1.0:
                processors.append(
                    TypicalLogitsWarper(mass=generation_config.typical_p, min_tokens_to_keep=min_tokens_to_keep)
                )
            if generation_config.epsilon_cutoff is not None and 0.0 < generation_config.epsilon_cutoff < 1.0:
                processors.append(
                    EpsilonLogitsWarper(
                        epsilon=generation_config.epsilon_cutoff, min_tokens_to_keep=min_tokens_to_keep
                    )
                )
            if generation_config.eta_cutoff is not None and 0.0 < generation_config.eta_cutoff < 1.0:
                processors.append(
                    EtaLogitsWarper(
                        epsilon=generation_config.eta_cutoff, min_tokens_to_keep=min_tokens_to_keep, device=device
                    )
                )

        # Watermarking should be after all logits processing is finished (see #34630)
        if generation_config.watermarking_config is not None:
            processors.append(
                generation_config.watermarking_config.construct_processor(
                    self.config.get_text_config().vocab_size, device
                )
            )

        # `LogitNormalization` should always be the last logit processor, when present
        if generation_config.renormalize_logits is True:
            processors.append(LogitNormalization())
        return processors

    def _get_stopping_criteria(
        self: "GenerativePreTrainedModel",
        generation_config: GenerationConfig,
        stopping_criteria: StoppingCriteriaList | None,
        tokenizer: Optional["PreTrainedTokenizerBase"] = None,
    ) -> StoppingCriteriaList:
        criteria = StoppingCriteriaList()
        if generation_config.max_length is not None:
            max_position_embeddings = getattr(self.config, "max_position_embeddings", None)
            criteria.append(
                MaxLengthCriteria(
                    max_length=generation_config.max_length,
                    max_position_embeddings=max_position_embeddings,
                )
            )
        if generation_config.max_time is not None:
            criteria.append(MaxTimeCriteria(max_time=generation_config.max_time))
        if generation_config.stop_strings is not None:
            if tokenizer is None:
                raise ValueError(
                    "There are one or more stop strings, either in the arguments to `generate` or in the "
                    "model's generation config, but we could not locate a tokenizer. When generating with "
                    "stop strings, you must pass the model's tokenizer to the `tokenizer` argument of `generate`."
                )
            criteria.append(StopStringCriteria(stop_strings=generation_config.stop_strings, tokenizer=tokenizer))
        if generation_config._eos_token_tensor is not None:
            criteria.append(EosTokenCriteria(eos_token_id=generation_config._eos_token_tensor))
        if (
            generation_config.is_assistant
            and generation_config.assistant_confidence_threshold is not None
            and generation_config.assistant_confidence_threshold > 0
        ):
            criteria.append(
                ConfidenceCriteria(assistant_confidence_threshold=generation_config.assistant_confidence_threshold)
            )
        criteria = self._merge_criteria_processor_list(criteria, stopping_criteria)
        return criteria

    def _merge_criteria_processor_list(
        self,
        default_list: LogitsProcessorList | StoppingCriteriaList,
        custom_list: LogitsProcessorList | StoppingCriteriaList,
    ) -> LogitsProcessorList | StoppingCriteriaList:
        """
        Merge user-defined processors/criteria with the ones instantiated inside `generate`. In case the same
        processor/criteria is present on both lists, use the user-defined one.

        (Note: up to v4.49.0, this function threw an exception is the same logit processor was found twice.)
        """
        if len(custom_list) == 0:
            return default_list

        final_list = type(default_list)()
        for default in default_list:
            using_custom = False
            for custom in custom_list:
                if type(custom) is type(default):
                    object_type = "stopping criteria" if isinstance(custom, StoppingCriteria) else "logits processor"
                    logger.warning_once(
                        f"A custom {object_type} of type {type(custom)} has been passed to `.generate()`, but it "
                        f"was also created in `.generate()`, given its parameterization. The custom {type(custom)} "
                        f"will take precedence. Please check the docstring of {type(custom)} to see related "
                        "`.generate()` flags."
                    )
                    final_list.append(custom)
                    using_custom = True
                    break
            if not using_custom:
                final_list.append(default)

        for custom in custom_list:
            if custom not in final_list:
                final_list.append(custom)
        return final_list

    def compute_transition_scores(
        self: "GenerativePreTrainedModel",
        sequences: torch.Tensor,
        scores: tuple[torch.Tensor],
        beam_indices: torch.Tensor | None = None,
        normalize_logits: bool = False,
    ) -> torch.Tensor:
        """
        Computes the transition scores of sequences given the generation scores (and beam indices, if beam search was
        used). This is a convenient method to quickly obtain the scores of the selected tokens at generation time.

        Parameters:
            sequences (`torch.LongTensor`):
                The generated sequences. The second dimension (sequence_length) is either equal to `max_length` or
                shorter if all batches finished early due to the `eos_token_id`.
            scores (`tuple(torch.FloatTensor)`):
                Transition scores for each vocabulary token at each generation step. Beam transition scores consisting
                of log probabilities of tokens conditioned on log softmax of previously generated tokens in this beam.
                Tuple of `torch.FloatTensor` with up to `max_new_tokens` elements (one element for each generated token),
                with each tensor of shape `(batch_size*num_beams, config.vocab_size)`.
            beam_indices (`torch.LongTensor`, *optional*):
                Beam indices of generated token id at each generation step. `torch.LongTensor` of shape
                `(batch_size*num_return_sequences, sequence_length)`. Only required if a `num_beams>1` at
                generate-time.
            normalize_logits (`bool`, *optional*, defaults to `False`):
                Whether to normalize the logits (which, for legacy reasons, may be unnormalized).

        Return:
            `torch.Tensor`: A `torch.Tensor` of shape `(batch_size*num_return_sequences, sequence_length)` containing
                the transition scores (logits)

        Examples:

        ```python
        >>> from transformers import GPT2Tokenizer, AutoModelForCausalLM
        >>> import numpy as np

        >>> tokenizer = GPT2Tokenizer.from_pretrained("gpt2")
        >>> model = AutoModelForCausalLM.from_pretrained("openai-community/gpt2")
        >>> tokenizer.pad_token_id = tokenizer.eos_token_id
        >>> inputs = tokenizer(["Today is"], return_tensors="pt")

        >>> # Example 1: Print the scores for each token generated with Greedy Search
        >>> outputs = model.generate(**inputs, max_new_tokens=5, return_dict_in_generate=True, output_scores=True)
        >>> transition_scores = model.compute_transition_scores(
        ...     outputs.sequences, outputs.scores, normalize_logits=True
        ... )
        >>> # input_length is the length of the input prompt for decoder-only models, like the GPT family, and 1 for
        >>> # encoder-decoder models, like BART or T5.
        >>> input_length = 1 if model.config.is_encoder_decoder else inputs.input_ids.shape[1]
        >>> generated_tokens = outputs.sequences[:, input_length:]
        >>> for tok, score in zip(generated_tokens[0], transition_scores[0]):
        ...     # | token | token string | log probability | probability
        ...     print(f"| {tok:5d} | {tokenizer.decode(tok):8s} | {score.numpy():.3f} | {np.exp(score.numpy()):.2%}")
        |   262 |  the     | -1.414 | 24.33%
        |  1110 |  day     | -2.609 | 7.36%
        |   618 |  when    | -2.010 | 13.40%
        |   356 |  we      | -1.859 | 15.58%
        |   460 |  can     | -2.508 | 8.14%

        >>> # Example 2: Reconstruct the sequence scores from Beam Search
        >>> outputs = model.generate(
        ...     **inputs,
        ...     max_new_tokens=5,
        ...     num_beams=4,
        ...     num_return_sequences=4,
        ...     return_dict_in_generate=True,
        ...     output_scores=True,
        ... )
        >>> transition_scores = model.compute_transition_scores(
        ...     outputs.sequences, outputs.scores, outputs.beam_indices, normalize_logits=False
        ... )
        >>> # If you sum the generated tokens' scores and apply the length penalty, you'll get the sequence scores.
        >>> # Tip 1: recomputing the scores is only guaranteed to match with `normalize_logits=False`. Depending on the
        >>> # use case, you might want to recompute it with `normalize_logits=True`.
        >>> # Tip 2: the output length does NOT include the input length
        >>> output_length = np.sum(transition_scores.numpy() < 0, axis=1)
        >>> length_penalty = model.generation_config.length_penalty
        >>> reconstructed_scores = transition_scores.sum(axis=1) / (output_length**length_penalty)
        >>> print(np.allclose(outputs.sequences_scores, reconstructed_scores))
        True
        ```"""
        # 1. In absence of `beam_indices`, we can assume that we come from e.g. greedy search, which is equivalent
        # to a beam search approach were the first (and only) beam is always selected
        if beam_indices is None:
            beam_indices = torch.arange(scores[0].shape[0]).view(-1, 1).to(sequences.device)
            beam_indices = beam_indices.expand(-1, len(scores))

        # 2. reshape scores as [batch_size*vocab_size, # generation steps] with # generation steps being
        # seq_len - input_length
        stacked_scores: torch.Tensor = torch.stack(scores).reshape(len(scores), -1).transpose(0, 1)

        # 3. Optionally normalize the logits (across the vocab dimension)
        if normalize_logits:
            stacked_scores = stacked_scores.reshape(
                -1, self.config.get_text_config().vocab_size, stacked_scores.shape[-1]
            )
            stacked_scores = torch.nn.functional.log_softmax(stacked_scores, dim=1)
            stacked_scores = stacked_scores.reshape(-1, stacked_scores.shape[-1])

        # 4. cut beam_indices to longest beam length
        beam_indices_mask = beam_indices < 0
        max_beam_length = (1 - beam_indices_mask.long()).sum(-1).max()
        beam_indices = beam_indices.clone()[:, :max_beam_length]
        beam_indices_mask = beam_indices_mask[:, :max_beam_length]

        # 5. Set indices of beams that finished early to 0; such indices will be masked correctly afterwards
        beam_indices[beam_indices_mask] = 0

        # 6. multiply beam_indices with vocab size to gather correctly from scores
        beam_sequence_indices = beam_indices * self.config.get_text_config().vocab_size

        # 7. Define which indices contributed to scores
        cut_idx = sequences.shape[-1] - max_beam_length
        indices = sequences[:, cut_idx:] + beam_sequence_indices

        # 8. Compute scores
        transition_scores = stacked_scores.gather(0, indices)

        # 9. Mask out transition_scores of beams that stopped early
        transition_scores[beam_indices_mask] = 0

        return transition_scores

    def _validate_generation_mode(
        self: "GenerativePreTrainedModel", generation_mode, generation_config, generation_mode_kwargs
    ):
        supported_modes = getattr(self, "_supported_generation_modes", None)
        if supported_modes is not None and generation_mode not in supported_modes:
            raise ValueError(
                f"{self.__class__.__name__} only supports {supported_modes}, but got "
                f"generation mode '{generation_mode}'."
            )

        if generation_mode == GenerationMode.BEAM_SEARCH and "streamer" in generation_mode_kwargs:
            raise ValueError(
                "`streamer` cannot be used with beam search (yet!). Make sure that `num_beams` is set to 1."
            )

        if generation_mode == GenerationMode.ASSISTED_GENERATION:
            if generation_config.num_return_sequences > 1:
                raise ValueError(
                    "num_return_sequences has to be 1 when doing assisted generate, "
                    f"but is {generation_config.num_return_sequences}."
                )
            if self._is_stateful:
                # In assisted generation we need the ability to confirm whether the model would pick certain tokens,
                # which is not possible with stateful models (they can't reset to a previous subset of generated text)
                raise ValueError(
                    f"assisted generation is not supported with stateful models, such as {self.__class__.__name__}"
                )

        if (assistant_model := generation_mode_kwargs.get("assistant_model")) is not None:
            if self.config.is_encoder_decoder and not assistant_model.config.is_encoder_decoder:
                attributes_to_check = ["encoder_attention_heads", "encoder_ffn_dim", "encoder_layers"]
                attributes_to_check = [attr for attr in dir(assistant_model.config) if attr in attributes_to_check]
                are_equal = all(
                    getattr(self.config, attr) == getattr(assistant_model.config, attr) for attr in attributes_to_check
                )
                if not are_equal:
                    raise ValueError(
                        "The main model and the assistant don't have compatible encoder-dependent input shapes. "
                        "Ensure you load the assistant with the correct encoder-decoder class, e.g. `AutoModelForSpeechSeq2Seq` for Whisper."
                    )

            doc_reference = (
                "(see https://huggingface.co/docs/transformers/en/generation_strategies#universal-assisted-decoding)"
            )
            if self.config.get_text_config().vocab_size == assistant_model.config.get_text_config().vocab_size:
                if "assistant_tokenizer" in generation_mode_kwargs:
                    raise ValueError(
                        f"`assistant_tokenizer` is not required when the main and assistant models use the same tokenizer. Please omit `assistant_tokenizer` from `generate()` {doc_reference}."
                    )
            else:
                if "tokenizer" not in generation_mode_kwargs or "assistant_tokenizer" not in generation_mode_kwargs:
                    raise ValueError(
                        f"The main and assistant models have different tokenizers. Please provide `tokenizer` and `assistant_tokenizer` to `generate()` {doc_reference}."
                    )

    def _validate_model_kwargs(self: "GenerativePreTrainedModel", model_kwargs: dict[str, Any]):
        """Validates model kwargs for generation. Generate argument typos will also be caught here."""
        # Excludes arguments that are handled before calling any model function
        if self.config.is_encoder_decoder:
            for key in ["decoder_input_ids"]:
                model_kwargs.pop(key, None)

        unused_model_args = []
        model_args = set(inspect.signature(self.prepare_inputs_for_generation).parameters)
        # `kwargs`/`model_kwargs` is often used to handle optional forward pass inputs like `attention_mask`. If
        # `prepare_inputs_for_generation` doesn't accept them, then a stricter check can be made ;)
        if "kwargs" in model_args or "model_kwargs" in model_args:
            model_args |= set(inspect.signature(self.forward).parameters)

        # Encoder-Decoder models may also need Encoder arguments from `model_kwargs`
        if self.config.is_encoder_decoder:
            base_model = getattr(self, self.base_model_prefix, None)

            # allow encoder kwargs
            encoder = getattr(self, "encoder", None)
            # `MusicgenForConditionalGeneration` has `text_encoder` and `audio_encoder`.
            # Also, it has `base_model_prefix = "encoder_decoder"` but there is no `self.encoder_decoder`
            # TODO: A better way to handle this.
            if encoder is None and base_model is not None:
                encoder = getattr(base_model, "encoder", None)

            if encoder is not None:
                encoder_model_args = set(inspect.signature(encoder.forward).parameters)
                model_args |= encoder_model_args

            # allow decoder kwargs
            decoder = getattr(self, "decoder", None)
            if decoder is None and base_model is not None:
                decoder = getattr(base_model, "decoder", None)

            if decoder is not None:
                decoder_model_args = set(inspect.signature(decoder.forward).parameters)
                model_args |= {f"decoder_{x}" for x in decoder_model_args}

        # TransformersKwargs are model-agnostic attention and generation arguments such as 'output_attentions'
        for key, value in model_kwargs.items():
            if (
                value is not None
                and key not in model_args
                and key not in TransformersKwargs.__optional_keys__
                and key != "debug_io"
            ):
                unused_model_args.append(key)

        if unused_model_args:
            raise ValueError(
                f"The following `model_kwargs` are not used by the model: {unused_model_args} (note: typos in the"
                " generate arguments will also show up in this list)"
            )

    def _validate_generated_length(
        self: "GenerativePreTrainedModel", generation_config, input_ids_length, has_default_max_length
    ):
        """Performs validation related to the resulting generated length"""
        # 1. Max length warnings related to poor parameterization
        if has_default_max_length and generation_config.max_new_tokens is None:
            # 20 is the default max_length of the generation config
            warnings.warn(
                f"Using the model-agnostic default `max_length` (={generation_config.max_length}) to control the "
                "generation length. We recommend setting `max_new_tokens` to control the maximum length of the "
                "generation.",
                UserWarning,
            )
        if input_ids_length >= generation_config.max_length:
            input_ids_string = "decoder_input_ids" if self.config.is_encoder_decoder else "input_ids"
            raise ValueError(
                f"Input length of {input_ids_string} is {input_ids_length}, but `max_length` is set to"
                f" {generation_config.max_length}. This can lead to unexpected behavior. You should consider"
                " increasing `max_length` or, better yet, setting `max_new_tokens`."
            )

        # 2. Min length warnings due to unfeasible parameter combinations
        min_length_error_suffix = (
            " Generation will stop at the defined maximum length. You should decrease the minimum length and/or "
            "increase the maximum length."
        )
        if has_default_max_length:
            min_length_error_suffix += (
                f" Note that `max_length` is set to {generation_config.max_length}, its default value."
            )
        if generation_config.min_length is not None and generation_config.min_length > generation_config.max_length:
            warnings.warn(
                f"Unfeasible length constraints: `min_length` ({generation_config.min_length}) is larger than"
                f" the maximum possible length ({generation_config.max_length})." + min_length_error_suffix,
                UserWarning,
            )
        if generation_config.min_new_tokens is not None:
            min_length = generation_config.min_new_tokens + input_ids_length
            if min_length > generation_config.max_length:
                warnings.warn(
                    f"Unfeasible length constraints: `min_new_tokens` ({generation_config.min_new_tokens}), when "
                    f"added to the prompt length ({input_ids_length}), is larger than"
                    f" the maximum possible length ({generation_config.max_length})." + min_length_error_suffix,
                    UserWarning,
                )

    def _prepare_generated_length(
        self: "GenerativePreTrainedModel",
        generation_config,
        has_default_max_length,
        has_default_min_length,
        model_input_name,
        input_ids_length,
        inputs_tensor,
    ):
        """Prepared max and min length in generation configs to avoid clashes between similar attributes"""

        if generation_config.max_new_tokens is not None:
            if not has_default_max_length and generation_config.max_length is not None:
                logger.warning(
                    f"Both `max_new_tokens` (={generation_config.max_new_tokens}) and `max_length`(="
                    f"{generation_config.max_length}) seem to have been set. `max_new_tokens` will take precedence. "
                    "Please refer to the documentation for more information. "
                    "(https://huggingface.co/docs/transformers/main/en/main_classes/text_generation)"
                )
            generation_config.max_length = generation_config.max_new_tokens + input_ids_length

        # If both `inputs_embeds` and `input_ids` are passed, we correct length with `inputs_tensor.shape`
        # We need to get max_length = inputs_embeds_len + max_new_tokens
        elif (
            model_input_name == "inputs_embeds"
            and input_ids_length != inputs_tensor.shape[1]
            and not self.config.is_encoder_decoder
            and not has_default_max_length
        ):
            generation_config.max_length -= inputs_tensor.shape[1]
        elif has_default_max_length:  # by default let's always generate 20 new tokens
            generation_config.max_length = generation_config.max_length + input_ids_length
            max_position_embeddings = getattr(self.config, "max_position_embeddings", None)
            if max_position_embeddings is not None:
                generation_config.max_length = min(generation_config.max_length, max_position_embeddings)

        # same for min length
        if generation_config.min_new_tokens is not None:
            if not has_default_min_length:
                logger.warning(
                    f"Both `min_new_tokens` (={generation_config.min_new_tokens}) and `min_length`(="
                    f"{generation_config.min_length}) seem to have been set. `min_new_tokens` will take precedence. "
                    "Please refer to the documentation for more information. "
                    "(https://huggingface.co/docs/transformers/main/en/main_classes/text_generation)"
                )
            generation_config.min_length = generation_config.min_new_tokens + input_ids_length

        elif (
            model_input_name == "inputs_embeds"
            and input_ids_length != inputs_tensor.shape[1]
            and not self.config.is_encoder_decoder
        ):
            generation_config.min_length = max(generation_config.min_length - inputs_tensor.shape[1], 0)

        return generation_config

    def _prepare_generation_config(
        self: "GenerativePreTrainedModel",
        generation_config: GenerationConfig | None,
        **kwargs: Any,
    ) -> tuple[GenerationConfig, dict]:
        """
        Prepares the base generation config, then applies any generation configuration options from kwargs. This
        function handles retrocompatibility with respect to configuration files.
        """
        # parameterization priority:
        # user-defined kwargs or `generation_config` > `self.generation_config` > global default values
        # TODO (joao): per-model generation config classes.

        generation_config_provided = generation_config is not None
        if generation_config is None:
            # Users may modify `model.config` to control generation. This is a legacy behavior and is not supported anymore
            if len(self.config._get_generation_parameters()) > 0:
                raise ValueError(
                    "You have modified the pretrained model configuration to control generation "
                    f"We detected the following values set - {self.config._get_generation_parameters()}. "
                    "This strategy to control generation is not supported anymore. Please use and modify `model.generation_config` "
                    "(see https://huggingface.co/docs/transformers/generation_strategies#default-text-generation-configuration )",
                )
            generation_config = GenerationConfig()

        # `torch.export.export` usually raises an exception if it is called
        # with ``strict=True``. deepcopy can only be processed if ``strict=False``.
        generation_config = copy.deepcopy(generation_config)

        # First set values from the loaded `self.generation_config`, then set default values (BC)
        #
        # Only update values that are `None`, i.e. these values were not explicitly set by users to `generate()`,
        # or values that are not present in the current config, i.e. custom entries that were set via `**kwargs`.
        # Thus we use the specific kwargs `defaults_only=True` (`None` values only) and `allow_custom_entries=True`
        # (custom entries are carried over).
        global_defaults = self.generation_config._get_default_generation_params()
        generation_config.update(**self.generation_config.to_dict(), defaults_only=True, allow_custom_entries=True)
        generation_config.update(**global_defaults, defaults_only=True)

        # Finally, if there are any kwargs, update config with it -> highest priority at the end
        model_kwargs = generation_config.update(**kwargs)

        # Related to #40039: prior to this PR, models with sliding window attention were forced to have
        # `cache_implementation="hybrid"` (the static sliding window cache). For these models, we now want to use
        # the dynamic sliding window cache by default, so we UNSET `cache_implementation` if it is a default value.
        # (if we're inside this branch, then it is because we're using default values from the Hub)
        if generation_config.cache_implementation == "hybrid":
            generation_config.cache_implementation = None

        # It doesn't make sense to allow kwargs and `generation_config`, that should be mutually exclusive
        if generation_config_provided and set(kwargs.keys()) - set(model_kwargs.keys()):
            generation_kwargs = set(kwargs.keys()) - set(model_kwargs.keys())
            logger.warning_once(
                f"Passing `generation_config` together with generation-related "
                f"arguments=({generation_kwargs}) is deprecated and will be removed in future versions. "
                "Please pass either a `generation_config` object OR all generation "
                "parameters explicitly, but not both.",
            )

        # Finally keep output_xxx args in `model_kwargs` so it can be passed to `forward`
        output_attentions = generation_config.output_attentions
        output_hidden_states = generation_config.output_hidden_states
        model_kwargs.update({"output_attentions": output_attentions} if output_attentions else {})
        model_kwargs.update({"output_hidden_states": output_hidden_states} if output_hidden_states else {})

        return generation_config, model_kwargs

    def _get_static_cache_init_shape(self: "GenerativePreTrainedModel") -> tuple[int, int] | None:
        """
        Returns the per-rank `(num_heads, head_dim)` to eagerly initialize a `StaticCache`, with the head count sharded
        for tensor parallelism. Returns `None` when the cache cannot be early initialized.
        """
        if hasattr(self, "hf_device_map") and len(set(self.hf_device_map.values())) > 1:
            # The model layers are on different devices
            return None
        text_config = self.config.get_text_config(decoder=True)
        tp_size = getattr(self, "_tp_size", None) or 1
        num_key_value_heads = getattr(text_config, "num_key_value_heads", None) or text_config.num_attention_heads
        if num_key_value_heads % tp_size != 0:
            # The model cannot be evenly sharded by head
            return None
        if getattr(text_config, "qk_head_dim", None) is not None:
            # MLA models have distinct key (`qk_head_dim`) and value (`v_head_dim`) sizes.
            return None
        head_dim = getattr(text_config, "head_dim", None) or text_config.hidden_size // text_config.num_attention_heads
        return num_key_value_heads // tp_size, head_dim

    def _prepare_static_cache(
        self: "GenerativePreTrainedModel",
        cache_implementation: str,
        batch_size: int,
        max_cache_len: int,
        prefill_chunk_size: int | None,
        model_kwargs,
    ) -> Cache:
        """
        Sets a cache for `generate`, that will persist across calls. A new cache will only be initialized a
        new `generate` call requires a larger cache or uses a different batch size.

        Returns the resulting cache object.
        """
        offload_cache = "offloaded" in cache_implementation

        cache_to_check: StaticCache | None = None
        if hasattr(self, "_cache"):
            if isinstance(self._cache, EncoderDecoderCache):
                cache_to_check = self._cache.self_attention_cache
            elif isinstance(self._cache, StaticCache):
                cache_to_check = self._cache

        need_new_cache = (
            cache_to_check is None
            or cache_to_check.offloading != offload_cache
            or cache_to_check.batch_size != batch_size
            or cache_to_check.get_max_length() < max_cache_len
        )

        encoder_decoder_cache = getattr(self, "_cache", None)
        if isinstance(encoder_decoder_cache, EncoderDecoderCache):
            need_new_cache = (
                need_new_cache
                or encoder_decoder_cache.cross_attention_cache.get_max_length()
                != model_kwargs["encoder_outputs"][0].shape[1]
            )

        if need_new_cache:
            self_attention_cache_kwargs = {
                "config": self.config.get_text_config(decoder=True),
                "max_cache_len": max_cache_len,
                "offloading": offload_cache,
            }
            self._cache = StaticCache(**self_attention_cache_kwargs)
            if self.config.is_encoder_decoder:
                cross_attention_cache_kwargs = {
                    "config": self.config.get_text_config(decoder=True),
                    "max_cache_len": model_kwargs["encoder_outputs"][0].shape[1],
                    "offloading": offload_cache,
                }
                self._cache = EncoderDecoderCache(self._cache, StaticCache(**cross_attention_cache_kwargs))
            elif prefill_chunk_size is not None:
                # Chunked prefill compiles the prefill, so eagerly init the fresh cache to avoid a recompile next call
                # (#46421). Skipped (-> lazy init) when it can't be initialized on a single device.
                init_shape = self._get_static_cache_init_shape()
                if init_shape is not None:
                    num_heads, head_dim = init_shape
                    self._cache.early_initialization(
                        batch_size=batch_size,
                        num_heads=num_heads,
                        head_dim=head_dim,
                        dtype=self.dtype,
                        device=self.device,
                    )
        else:
            self._cache.reset()
        return self._cache

    @classmethod
    def _supports_default_dynamic_cache(cls: type["GenerativePreTrainedModel"]) -> bool:
        """
        Return `True` if current model can use a `DynamicCache` instance when initializing the `past_key_values`.
        """
        # NOTE: remove xlnet/reformer when the models are deprecated, non-standard model architecture/cache name
        unsupported_model_names = (
            "reformer",
            "minimax",
            "xlnet",
            "olmohybrid",  # olmo_hybrid cannot use linear attention cache for now as it uses split k,q,v conv states
            "rwkv",
            "xlstm",
        )
        # The "minimax" exclusion targets the original linear-attention MiniMax (custom cache); the later
        # MiniMax M2 / M3 are standard attention models that use the regular Dynamic/Static caches.
        name = cls.__name__.lower()
        return (
            "minimaxm2" in name
            or "minimaxm3" in name
            or all(unsupported_name not in name for unsupported_name in unsupported_model_names)
        )

    def _prepare_cache_for_generation(
        self: "GenerativePreTrainedModel",
        generation_config: GenerationConfig,
        model_kwargs: dict,
        generation_mode: GenerationMode,
        batch_size: int,
        max_cache_length: int,
    ) -> bool:
        """
        Prepares the cache for generation (if applicable), given `generate`'s parameterization. If a cache is
        instantiated, writes it to `model_kwargs`, under the name expected by the model.
        """

        # TODO @raushan, unify cache arg naming for all models
        is_linear_attn_cache = "mamba" in self.__class__.__name__.lower()
        cache_name = "past_key_values" if not is_linear_attn_cache else "cache_params"

        # Quick escape route 1: if the user specifies a cache, we only need to check for conflicting `generate` arguments
        user_defined_cache = model_kwargs.get(cache_name)
        if user_defined_cache is not None:
            if generation_config.cache_implementation is not None:
                raise ValueError(
                    f"Passing both `cache_implementation` (used to initialize certain caches) and `{cache_name}` (a "
                    "Cache object) is unsupported. Please use only one of the two."
                )
            if isinstance(user_defined_cache, tuple):
                raise ValueError(
                    "Passing a tuple of `past_key_values` is not supported anymore. Please use a `Cache` instance."
                )
            return

        # Quick escape route 2: if the user specifies no cache is to be used. (conflicting arguments are handled in
        # `generation_config.validate()`)
        if generation_config.use_cache is False:
            return

        # Quick escape route 3: model that supply it in `prepare_inputs_for_generation` (mamba, zamba, ...)
        if not self._supports_default_dynamic_cache():
            if generation_config.cache_implementation is not None:
                logger.warning_once(
                    "This model does not support `Cache` instances. `cache_implementation` (set to "
                    f"{generation_config.cache_implementation}) will be ignored.",
                )
            return

        # Otherwise we NEED to prepare a cache, based on `generation_config.cache_implementation`

        # Assisted decoding and contrastive search require cache rollback, which is incompatible with sliding layers.
        # To handle this, we skip passing the model config to DynamicCache (forcing a full-layer cache).
        # The "dynamic_full" option is a shortcut for generate() users to avoid sliding layers on their own.
        if generation_mode in (GenerationMode.ASSISTED_GENERATION, GenerationMode.CONTRASTIVE_SEARCH):
            if generation_config.cache_implementation is not None:
                logger.warning_once(
                    "An assistant model is provided, using a dynamic cache instead of a cache of type="
                    f"'{generation_config.cache_implementation}'."
                )
            generation_config.cache_implementation = "dynamic_full"

        dynamic_cache_kwargs = {}
        dynamic_cache_kwargs["config"] = self.config.get_text_config(decoder=True)

        if generation_config.cache_implementation == "offloaded":
            dynamic_cache_kwargs["offloading"] = True

        if generation_config.cache_implementation in ALL_STATIC_CACHE_IMPLEMENTATIONS:
            if generation_config.cache_implementation in DEPRECATED_STATIC_CACHE_IMPLEMENTATIONS:
                logger.warning_once(
                    f"Using `cache_implementation='{generation_config.cache_implementation}' is deprecated "
                    f"and will be removed in v5.13. Please only use one of {STATIC_CACHE_IMPLEMENTATIONS}, "
                    "and the layer structure will be inferred automatically."
                )
            # `max_cache_len` lets the static cache be sized for the worst case across calls, so that later calls
            # with a longer prompt or a larger `max_new_tokens` (up to that ceiling) reuse the same cache instead of
            # triggering a reallocation (and a `torch.compile` recompilation). Without it, the cache is sized to the
            # current call's `max_length` only. See #46424.
            if generation_config.max_cache_len is not None:
                max_cache_length = max(max_cache_length, generation_config.max_cache_len)
            cache_batch_size = max(generation_config.num_beams, generation_config.num_return_sequences) * batch_size
            model_kwargs[cache_name] = self._prepare_static_cache(
                cache_implementation=generation_config.cache_implementation,
                batch_size=cache_batch_size,
                max_cache_len=max_cache_length,
                prefill_chunk_size=generation_config.prefill_chunk_size,
                model_kwargs=model_kwargs,
            )
        elif generation_config.cache_implementation == "quantized":
            if self.config.is_encoder_decoder or not self._supports_default_dynamic_cache():
                raise ValueError(
                    "This model does not support the quantized cache. If you want your model to support quantized "
                    "cache, please open an issue and tag @zucchini-nlp."
                )

            cache_config = generation_config.cache_config if generation_config.cache_config is not None else {}
            cache_config.setdefault("config", self.config.get_text_config(decoder=True))
            backend = cache_config.pop("backend", "quanto")
            model_kwargs[cache_name] = QuantizedCache(backend=backend, **cache_config)
        # i.e. `cache_implementation` in [None, "dynamic", "offloaded", "dynamic_full"]
        # TODO: prepare linear cache from a single API, instead of creating in modeling code
        else:
            model_kwargs[cache_name] = DynamicCache(**dynamic_cache_kwargs)

        if (
            self.config.is_encoder_decoder
            and cache_name in model_kwargs
            and not isinstance(model_kwargs[cache_name], EncoderDecoderCache)
        ):
            model_kwargs[cache_name] = EncoderDecoderCache(
                model_kwargs[cache_name],  # self-attention cache
                DynamicCache(**dynamic_cache_kwargs),  # cross-attention cache
            )

    def _supports_logits_to_keep(self: "GenerativePreTrainedModel") -> bool:
        """
        Return True if the current model supports the keyword argument `logits_to_keep` in forward()
        to save memory. Checking it in this way allows to avoid using a new model attribute.
        """
        return "logits_to_keep" in set(inspect.signature(self.forward).parameters.keys())

    def _prepare_special_tokens(
        self: "GenerativePreTrainedModel",
        generation_config: GenerationConfig,
        kwargs_has_attention_mask: bool | None = None,
        device: torch.device | str | None = None,
    ):
        """
        Prepares the special tokens for generation, overwriting the generation config with their processed versions
        converted to tensor.

        Note that `generation_config` is changed in place and stops being serializable after this method is called.
        That is no problem if called within `generate` (`generation_config` is a local copy that doesn't leave the
        function). However, if called outside `generate`, consider creating a copy of `generation_config` first.
        """

        # Convert special tokens to tensors
        def _tensor_or_none(token, device=None):
            if token is None:
                return token

            device = device if device is not None else self.device
            if isinstance(token, torch.Tensor):
                return token.to(device)
            return torch.tensor(token, device=device, dtype=torch.long)

        bos_token_tensor = _tensor_or_none(generation_config.bos_token_id, device=device)
        eos_token_tensor = _tensor_or_none(generation_config.eos_token_id, device=device)
        pad_token_tensor = _tensor_or_none(generation_config.pad_token_id, device=device)
        decoder_start_token_tensor = _tensor_or_none(generation_config.decoder_start_token_id, device=device)

        # for BC we also try to get `decoder_start_token_id` or `bos_token_id` (#30892)
        if self.config.is_encoder_decoder:
            decoder_start_token_tensor = (
                decoder_start_token_tensor if decoder_start_token_tensor is not None else bos_token_tensor
            )

        # We can have more than one eos token. Always treat it as a 1D tensor (when it exists).
        if eos_token_tensor is not None and eos_token_tensor.ndim == 0:
            eos_token_tensor = eos_token_tensor.unsqueeze(0)

        # Set pad token if unset (and there are conditions to do so)
        if pad_token_tensor is None and eos_token_tensor is not None:
            if kwargs_has_attention_mask is not None and not kwargs_has_attention_mask:
                logger.warning(
                    "The attention mask and the pad token id were not set. As a consequence, you may observe "
                    "unexpected behavior. Please pass your input's `attention_mask` to obtain reliable results."
                )
            pad_token_tensor = eos_token_tensor[0]
            logger.warning(f"Setting `pad_token_id` to `eos_token_id`:{pad_token_tensor} for open-end generation.")

        # Sanity checks/warnings
        if self.config.is_encoder_decoder and decoder_start_token_tensor is None:
            raise ValueError(
                "`decoder_start_token_id` or `bos_token_id` has to be defined for encoder-decoder generation."
            )
        if eos_token_tensor is not None and torch.isin(eos_token_tensor, pad_token_tensor).any():
            if kwargs_has_attention_mask is not None and not kwargs_has_attention_mask:
                logger.warning_once(
                    "The attention mask is not set and cannot be inferred from input because pad token is same as "
                    "eos token. As a consequence, you may observe unexpected behavior. Please pass your input's "
                    "`attention_mask` to obtain reliable results."
                )
        if eos_token_tensor is not None and (
            torch.is_floating_point(eos_token_tensor) or (eos_token_tensor < 0).any()
        ):
            logger.warning(
                f"`eos_token_id` should consist of positive integers, but is {eos_token_tensor}. Your generation "
                "will not stop until the maximum length is reached. Depending on other flags, it may even crash."
            )

        # Update generation config with the updated special tokens tensors
        # NOTE: this must be written into a different attribute name than the one holding the original special tokens
        # (in their non-tensor form), in order to enable end-to-end compilation. See
        # https://pytorch.org/docs/stable/torch.compiler_cudagraph_trees.html#limitations
        generation_config._bos_token_tensor = bos_token_tensor
        generation_config._eos_token_tensor = eos_token_tensor
        generation_config._pad_token_tensor = pad_token_tensor
        generation_config._decoder_start_token_tensor = decoder_start_token_tensor

    def _valid_auto_compile_criteria(
        self: "GenerativePreTrainedModel", model_kwargs: dict[str, Any], generation_config: GenerationConfig
    ) -> bool:
        """
        Determines whether to trigger auto-compilation of the model's forward pass at generation time.
        """
        # Override: honor `disable_compile` flag
        if generation_config.disable_compile:
            return False

        cache = model_kwargs.get("past_key_values", model_kwargs.get("cache_params"))

        # Base logic
        valid_hardware = self.device.type in ["cuda", "xpu", "neuron", "tpu"] or bool(
            generation_config.compile_config is not None and generation_config.compile_config._compile_all_devices
        )
        # Note: for some models that only use linear attention (e.g. Mamba), even a DynamicCache is compileable since all
        # layers are, but we don't want to ALWAYS compile when calling `generate`, so we check the type
        using_compilable_cache = cache is not None and cache.is_compileable and type(cache) is not DynamicCache
        can_compile = valid_hardware and using_compilable_cache

        # Exception 1: Some quantization methods do not support compilation
        if getattr(self, "hf_quantizer", None) is not None:
            can_compile &= self.hf_quantizer.is_compileable

        if hasattr(self, "hf_device_map"):
            all_model_devices = set(self.hf_device_map.values())
            # Exception 2: Don't compile if the model is using CPU offload (as of April 2025, this results in a crash)
            has_cpu_offload = "cpu" in all_model_devices and len(all_model_devices) > 1
            can_compile &= not has_cpu_offload

            # Exception 3: Disk offload is not supported for compilation
            has_disk_offload = "disk" in all_model_devices
            can_compile &= not has_disk_offload

        # If the user has manually specified compilation options, but compilation is not possible, let's warn
        # them
        if generation_config.compile_config is not None and not can_compile:
            logger.warning_once(
                "You have set `compile_config`, but we are unable to meet the criteria for compilation. Compilation "
                "will be skipped."
            )

        if can_compile:
            # Finally: if we can compile, disable tokenizers parallelism
            os.environ["TOKENIZERS_PARALLELISM"] = "0"

            # If we use FA and a static cache, we cannot compile with fullgraph
            if is_flash_attention_requested(self.config):
                # only raise warning if the user passed an explicit compile-config
                if generation_config.compile_config is not None and generation_config.compile_config.fullgraph:
                    logger.warning_once(
                        "When using Flash Attention and a static cache, you cannot use the option `CompileConfig(fullgraph=True)` as "
                        "FA introduces graph breaks. We overrode the option with `fullgraph=False`."
                    )
                    generation_config.compile_config.fullgraph = False

        return can_compile

    @contextmanager
    def _optimize_model_for_decode(self: "GenerativePreTrainedModel"):
        original_experts_implementation = self.config._experts_implementation
        # On non-CPU devices, 'batched_mm' can trade off a bit of memory (by duplicating selected experts weights)
        # for much better speed during decoding, especially for smaller inputs. On CPU, grouped_mm is usually better.
        if original_experts_implementation == "grouped_mm" and self.device.type != "cpu":
            logger.info_once(
                "We will be switching to 'batched_mm' for the decoding stage as it is much more performant than 'grouped_mm' on smaller inputs. "
                "If you experience any issues with this, please open an issue on the Hugging Face Transformers GitHub repository.",
            )
            self.set_experts_implementation("batched_mm")

        try:
            yield
        finally:
            if original_experts_implementation == "grouped_mm" and self.device.type != "cpu":
                self.set_experts_implementation(original_experts_implementation)

    def _get_deprecated_gen_repo(
        self,
        generation_mode: GenerationMode,
        trust_remote_code: bool,
        custom_generate: str | None = None,
    ) -> str | None:
        """
        Returns the Hub repo for a deprecated generation mode, if any.
        """
        if custom_generate is not None or "/" not in (repo := GENERATION_MODES_MAPPING[generation_mode]):
            return None

        logger.warning_once(
            f"{generation_mode.name.replace('_', ' ').title()} was moved to a `custom_generate` repo: https://hf.co/{repo}. "
            f"To prevent loss of backward compatibility, add `custom_generate='{repo}'` "
            "to your `generate` call before v4.62.0."
        )
        if not trust_remote_code:
            raise ValueError(
                f"{generation_mode.name.replace('_', ' ').title()} requires `trust_remote_code=True` in your `generate` call, "
                f"since it loads https://hf.co/{repo}."
            )
        return repo

    def _extract_generation_mode_kwargs(
        self,
        custom_generate,
        kwargs,
        synced_gpus,
        assistant_model,
        streamer,
    ) -> dict[str, Any]:
        """
        Extracts and returns the generation mode related keyword arguments from the provided kwargs.
        """
        generation_mode_kwargs = {
            "tokenizer": kwargs.pop("tokenizer", None),
            "assistant_tokenizer": kwargs.pop("assistant_tokenizer", None),
            "assistant_model": assistant_model,
            "streamer": streamer,
        }
        world_size = dist.get_world_size() if dist.is_available() and dist.is_initialized() else 1  # type: ignore
        generation_mode_kwargs["synced_gpus"] = (
            (is_deepspeed_zero3_enabled() or is_fsdp_managed_module(self)) and world_size > 1
            if synced_gpus is None
            else synced_gpus
        )
        generation_mode_kwargs = {k: v for k, v in generation_mode_kwargs.items() if v is not None}
        # Custom_generate callables can have their own set of arguments
        # To extract them, we compare the signature with the standard _sample method
        if isinstance(custom_generate, Callable):
            usual_mode_kwargs = inspect.signature(GenerationMixin._sample).parameters.keys()
            custom_generate_kwargs = inspect.signature(custom_generate).parameters.keys()
            new_custom_keys = custom_generate_kwargs - usual_mode_kwargs
            generation_mode_kwargs = {k: kwargs.pop(k) for k in new_custom_keys if k in kwargs}
        return generation_mode_kwargs

    @torch.no_grad()
    def generate(
        self: "GenerativePreTrainedModel",
        inputs: torch.Tensor | None = None,
        generation_config: GenerationConfig | None = None,
        logits_processor: LogitsProcessorList | None = None,
        stopping_criteria: StoppingCriteriaList | None = None,
        prefix_allowed_tokens_fn: Callable[[int, torch.Tensor], list[int]] | None = None,
        synced_gpus: bool | None = None,
        assistant_model: Optional["PreTrainedModel"] = None,
        streamer: Optional["BaseStreamer"] = None,
        negative_prompt_ids: torch.Tensor | None = None,
        negative_prompt_attention_mask: torch.Tensor | None = None,
        custom_generate: str | Callable | None = None,
        **kwargs,
    ) -> GenerateOutput | torch.LongTensor:
        r"""

        Generates sequences of token ids for models with a language modeling head.

        <Tip warning={true}>

        Most generation-controlling parameters are set in `generation_config` which, if not passed, will be set to the
        model's default generation configuration. You can override any `generation_config` by passing the corresponding
        parameters to generate(), e.g. `.generate(inputs, num_beams=4, do_sample=True)`.

        For an overview of generation strategies and code examples, check out the [following
        guide](../generation_strategies).

        </Tip>

        Parameters:
            inputs (`torch.Tensor` of varying shape depending on the modality, *optional*):
                The sequence used as a prompt for the generation or as model inputs to the encoder. If `None` the
                method initializes it with `bos_token_id` and a batch size of 1. For decoder-only models `inputs`
                should be in the format of `input_ids`. For encoder-decoder models *inputs* can represent any of
                `input_ids`, `input_values`, `input_features`, or `pixel_values`.
            generation_config ([`~generation.GenerationConfig`], *optional*):
                The generation configuration to be used as base parametrization for the generation call. `**kwargs`
                passed to generate matching the attributes of `generation_config` will override them. If
                `generation_config` is not provided, the default will be used, which has the following loading
                priority: 1) from the `generation_config.json` model file, if it exists; 2) from the model
                configuration. Please note that unspecified parameters will inherit [`~generation.GenerationConfig`]'s
                default values, whose documentation should be checked to parameterize generation.
            logits_processor (`LogitsProcessorList`, *optional*):
                Custom logits processors that complement the default logits processors built from arguments and
                generation config. If a logit processor is passed that is already created with the arguments or a
                generation config an error is thrown. This feature is intended for advanced users.
            stopping_criteria (`StoppingCriteriaList`, *optional*):
                Custom stopping criteria that complements the default stopping criteria built from arguments and a
                generation config. If a stopping criteria is passed that is already created with the arguments or a
                generation config an error is thrown. If your stopping criteria depends on the `scores` input, make
                sure you pass `return_dict_in_generate=True, output_scores=True` to `generate`. This feature is
                intended for advanced users.
            prefix_allowed_tokens_fn (`Callable[[int, torch.Tensor], list[int]]`, *optional*):
                If provided, this function constraints the beam search to allowed tokens only at each step. If not
                provided no constraint is applied. This function takes 2 arguments: the batch ID `batch_id` and
                `input_ids`. It has to return a list with the allowed tokens for the next generation step conditioned
                on the batch ID `batch_id` and the previously generated tokens `inputs_ids`. This argument is useful
                for constrained generation conditioned on the prefix, as described in [Autoregressive Entity
                Retrieval](https://huggingface.co/papers/2010.00904).
            synced_gpus (`bool`, *optional*):
                Whether to continue running the while loop until max_length. Unless overridden, this flag will be set
                to `True` if using `FullyShardedDataParallel` or DeepSpeed ZeRO Stage 3 with multiple GPUs to avoid
                deadlocking if one GPU finishes generating before other GPUs. Otherwise, defaults to `False`.
            assistant_model (`PreTrainedModel`, *optional*):
                An assistant model that can be used to accelerate generation. The assistant model must have the exact
                same tokenizer. The acceleration is achieved when forecasting candidate tokens with the assistant model
                is much faster than running generation with the model you're calling generate from. As such, the
                assistant model should be much smaller.
            streamer (`BaseStreamer`, *optional*):
                Streamer object that will be used to stream the generated sequences. Generated tokens are passed
                through `streamer.put(token_ids)` and the streamer is responsible for any further processing.
            negative_prompt_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
                The negative prompt needed for some processors such as CFG. The batch size must match the input batch
                size. This is an experimental feature, subject to breaking API changes in future versions.
            negative_prompt_attention_mask (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
                Attention_mask for `negative_prompt_ids`.
            custom_generate (`str` or `Callable`, *optional*):
                One of the following:
                - `str` (Hugging Face Hub repository name): runs the custom `generate` function defined at
                  `custom_generate/generate.py` in that repository instead of the standard `generate` method. The
                  repository fully replaces the generation logic, and the return type may differ.
                - `str` (local repository path): same as above but from a local path. Local directories also
                  require `trust_remote_code=True` because the local `custom_generate/generate.py` is executed.
                - `Callable`: `generate` will perform the usual input preparation steps, then call the provided callable to
                  run the decoding loop.
                For more information, see [the docs](../../generation_strategies#custom-generation-methods).
            kwargs (`dict[str, Any]`, *optional*):
                Ad hoc parametrization of `generation_config` and/or additional model-specific kwargs that will be
                forwarded to the `forward` function of the model. If the model is an encoder-decoder model, encoder
                specific kwargs should not be prefixed and decoder specific kwargs should be prefixed with *decoder_*.

        Return:
            [`~utils.ModelOutput`] or `torch.LongTensor`: A [`~utils.ModelOutput`] (if `return_dict_in_generate=True`
            or when `config.return_dict_in_generate=True`) or a `torch.LongTensor`.

                If the model is *not* an encoder-decoder model (`model.config.is_encoder_decoder=False`), the possible
                [`~utils.ModelOutput`] types are:

                    - [`~generation.GenerateDecoderOnlyOutput`],
                    - [`~generation.GenerateBeamDecoderOnlyOutput`]

                If the model is an encoder-decoder model (`model.config.is_encoder_decoder=True`), the possible
                [`~utils.ModelOutput`] types are:

                    - [`~generation.GenerateEncoderDecoderOutput`],
                    - [`~generation.GenerateBeamEncoderDecoderOutput`]
        """
        # 0.a. If requested, load an arbitrary generation recipe from the Hub and run it instead
        trust_remote_code = kwargs.pop("trust_remote_code", None)

        if custom_generate is not None and isinstance(custom_generate, str):
            # Get all `generate` arguments in a single variable. Custom functions are responsible for handling them:
            # they receive the same inputs as `generate`, with `model` instead of `self` and excluding the arguments to
            # trigger the custom generation. They can access to methods from `GenerationMixin` through `model`.
            global_keys_to_exclude = {
                "self",
                "kwargs",
                "global_keys_to_exclude",
                "trust_remote_code",
                "custom_generate",
            }
            generate_arguments = {key: value for key, value in locals().items() if key not in global_keys_to_exclude}
            generate_arguments.update(kwargs)

            custom_generate_function = self.load_custom_generate(
                custom_generate, trust_remote_code=trust_remote_code, **kwargs
            )
            return custom_generate_function(model=self, **generate_arguments)

        # 0.b. If requested, switched to continuous batching generation
        if kwargs.get("cache_implementation") == "paged":
            logger.warning(
                "Detected cache_implementation=paged: switching to continuous batching. You should consider using "
                "generate_batch directly instead."
            )

            # generate_batch expects a list of lists of ints, so we create it from the inputs or input_ids
            inputs = inputs if inputs is not None else kwargs.get("input_ids")
            if inputs is None:
                raise ValueError("inputs or input_ids must be provided for CB generation.")

            if inputs.dim() == 1:
                inputs = inputs.unsqueeze(0).tolist()
            elif inputs.dim() == 2:
                inputs = inputs.tolist()
            else:
                raise ValueError(f"inputs must be a 1D or 2D tensor, got {inputs.dim() = }")

            # some arguments are not supported for continuous batching
            if stopping_criteria is not None:
                raise NotImplementedError(
                    f"stopping_criteria is not supported for continuous batching. Got {stopping_criteria = }"
                )
            if prefix_allowed_tokens_fn is not None:
                raise NotImplementedError(
                    f"prefix_allowed_tokens_fn is not supported for continuous batching. Got {prefix_allowed_tokens_fn = }"
                )
            if assistant_model is not None:
                raise NotImplementedError(
                    f"assistant_model is not supported for continuous batching. Got {assistant_model = }"
                )
            if streamer is not None:  # TODO: actually this could be supported
                raise NotImplementedError(f"streaming is not supported for continuous batching. Got {streamer = }")
            if negative_prompt_ids is not None:
                raise NotImplementedError(
                    f"negative_prompt_ids is not supported for continuous batching. Got {negative_prompt_ids = }"
                )
            if negative_prompt_attention_mask is not None:
                raise NotImplementedError(
                    f"negative_prompt_attention_mask is not supported for continuous batching. Got {negative_prompt_attention_mask = }"
                )

            # others are ignored
            if synced_gpus is not None:
                logger.warning(f"synced_gpus is not ignored for continuous batching. Got {synced_gpus = }")
            num_beams = kwargs.get("num_beams", 1)
            if num_beams > 1:  # FIXME: remove this once CB supports num_beams (which is planned)
                logger.warning(f"num_beams is not supported for continuous batching yet. Got {num_beams = }. ")

            # switch to CB
            outputs = self.generate_batch(
                inputs=inputs,
                generation_config=self._prepare_generation_config(generation_config, **kwargs)[0],
                **kwargs,
            )
            sequences = [
                outputs[f"req_{i}"].prompt_ids + outputs[f"req_{i}"].generated_tokens for i in range(len(outputs))
            ]

            # To use the same indexing (outputs[0]) as the regular generate method, we unsqueeze the tensor
            sequences_as_tensor = torch.tensor(sequences, dtype=torch.long, device=self.device)
            sequences_as_tensor = sequences_as_tensor.unsqueeze(0)
            return sequences_as_tensor

        # 1. Handle kwargs, `generation_config`, validate them and obtain generation mode
        generation_mode_kwargs = self._extract_generation_mode_kwargs(
            custom_generate,
            kwargs,
            synced_gpus,
            assistant_model,
            streamer,
        )

        # Check length values before updating the config with defaults. We'll use it later to define the final min/max length (# 6)
        has_default_max_length = (
            kwargs.get("max_length") is None
            and (generation_config is None or generation_config.max_length is None)
            and self.generation_config.max_length is None
        )
        has_default_min_length = (
            kwargs.get("min_length") is None
            and (generation_config is None or generation_config.min_length is None)
            and self.generation_config.min_length is None
        )
        generation_config, model_kwargs = self._prepare_generation_config(generation_config, **kwargs)

        generation_mode = generation_config.get_generation_mode(assistant_model)
        deprecated_mode_repo = self._get_deprecated_gen_repo(generation_mode, trust_remote_code, custom_generate)

        if isinstance(custom_generate, Callable):
            decoding_method = custom_generate
        elif deprecated_mode_repo is None:
            # type() required to access the unbound class-level method
            decoding_method = getattr(type(self), GENERATION_MODES_MAPPING[generation_mode])

        self._validate_model_kwargs(model_kwargs.copy())
        self._validate_generation_mode(generation_mode, generation_config, generation_mode_kwargs)

        # Deprecation-related step: set Hub repo for deprecated strategies.
        # NOTE: This must come after initializing generation_config, since we need it to determine if this is a deprecated mode.
        # It must also be before any preparation steps, since Hub repos expect to be loaded before preparation steps.
        # TODO joao, manuel: remove this in v4.62.0
        if deprecated_mode_repo is not None:
            return GenerationMixin.generate(
                self,
                inputs=inputs,
                generation_config=generation_config,
                logits_processor=logits_processor,
                stopping_criteria=stopping_criteria,
                prefix_allowed_tokens_fn=prefix_allowed_tokens_fn,
                assistant_model=assistant_model,
                negative_prompt_ids=negative_prompt_ids,
                negative_prompt_attention_mask=negative_prompt_attention_mask,
                custom_generate=deprecated_mode_repo,
                trust_remote_code=trust_remote_code,
                **generation_mode_kwargs,
                **kwargs,
            )

        # 2. Set generation parameters if not already defined
        logits_processor = logits_processor if logits_processor is not None else LogitsProcessorList()
        stopping_criteria = stopping_criteria if stopping_criteria is not None else StoppingCriteriaList()

        accepts_attention_mask = "attention_mask" in set(inspect.signature(self.forward).parameters.keys())
        kwargs_has_attention_mask = model_kwargs.get("attention_mask", None) is not None

        # 3. Define model inputs
        inputs_tensor, model_input_name, model_kwargs = self._prepare_model_inputs(
            inputs, generation_config.bos_token_id, model_kwargs
        )
        # Some generation modes (e.g. assisted) need `inputs_tensor` to rerun encoder.forward()
        if "inputs_tensor" in inspect.signature(decoding_method).parameters.keys():
            generation_mode_kwargs["inputs_tensor"] = inputs_tensor
        batch_size = inputs_tensor.shape[0]

        device = inputs_tensor.device
        self._prepare_special_tokens(generation_config, kwargs_has_attention_mask, device=device)

        # decoder-only models must use left-padding for batched generation.
        if not self.config.is_encoder_decoder:
            # If `input_ids` was given, check if the last id in any sequence is `pad_token_id`
            # Note: If using, `inputs_embeds` this check does not work, because we want to be more hands-off.
            if generation_config._pad_token_tensor is not None and batch_size > 1 and len(inputs_tensor.shape) == 2:
                # When an attention mask is provided, use it to detect right-padding (more reliable than
                # checking token ids, which can produce false positives when pad_token_id == eos_token_id
                # or pad_token_id == bos_token_id, as is the case for Qwen3 and other models).
                attention_mask = model_kwargs.get("attention_mask", None)
                if attention_mask is not None and attention_mask.shape == inputs_tensor.shape:
                    # Right-padding means there are zeros (masked positions) at the end of some sequences
                    has_right_padding = torch.any(attention_mask[:, -1] == 0).item()
                else:
                    # Fallback: check if the last token is a pad token (original heuristic)
                    has_right_padding = torch.sum(inputs_tensor[:, -1] == generation_config._pad_token_tensor) > 0
                if has_right_padding:
                    logger.warning(
                        "A decoder-only architecture is being used, but right-padding was detected! For correct "
                        "generation results, please set `padding_side='left'` when initializing the tokenizer."
                    )

        # 4. Define other model kwargs
        # decoder-only models with inputs_embeds forwarding must use caching (otherwise we can't detect whether we are
        # generating the first new token or not, and we only want to use the embeddings for the first new token)
        if not self.config.is_encoder_decoder and model_input_name == "inputs_embeds":
            generation_config.use_cache = True

        if not kwargs_has_attention_mask and not self.config.is_encoder_decoder and accepts_attention_mask:
            model_kwargs["attention_mask"] = self._prepare_attention_mask_for_generation(
                inputs_tensor, generation_config, model_kwargs
            )
        elif kwargs_has_attention_mask:
            # TODO (joao): generalize this check with other types of inputs
            if model_input_name == "input_ids" and len(model_kwargs["attention_mask"].shape) > 2:
                raise ValueError("`attention_mask` passed to `generate` must be 2D.")

        kwargs_has_position_ids = model_kwargs.get("position_ids", None) is not None
        accepts_position_ids = "position_ids" in set(inspect.signature(self.forward).parameters.keys())
        if not kwargs_has_position_ids and accepts_position_ids and not self.config.is_encoder_decoder:
            model_kwargs["position_ids"] = self._prepare_position_ids_for_generation(inputs_tensor, model_kwargs)

        if self.config.is_encoder_decoder and "encoder_outputs" not in model_kwargs:
            # if model is encoder decoder encoder_outputs are created and added to `model_kwargs`
            model_kwargs = self._prepare_encoder_decoder_kwargs_for_generation(
                inputs_tensor, model_kwargs, model_input_name, generation_config
            )

        # 5. Prepare `input_ids` which will be used for auto-regressive generation
        if self.config.is_encoder_decoder:
            input_ids, model_kwargs = self._prepare_decoder_input_ids_for_generation(
                batch_size=batch_size,
                model_input_name=model_input_name,
                model_kwargs=model_kwargs,
                decoder_start_token_id=generation_config._decoder_start_token_tensor,
                device=inputs_tensor.device,
            )
        else:
            input_ids = inputs_tensor if model_input_name == "input_ids" else model_kwargs.pop("input_ids")

        # Expand inputs depending on the generation mode
        input_ids, model_kwargs = self._expand_inputs_for_generation(
            input_ids=input_ids,
            expand_size=max(generation_config.num_beams, generation_config.num_return_sequences),
            is_encoder_decoder=self.config.is_encoder_decoder,
            **model_kwargs,
        )

        if generation_config.token_healing:
            input_ids = self.heal_tokens(input_ids, generation_mode_kwargs.get("tokenizer"))

        if streamer is not None:
            streamer.put(input_ids.cpu())

        # 6. Prepare `max_length` depending on other stopping criteria.
        input_ids_length = input_ids.shape[1]
        generation_config = self._prepare_generated_length(
            generation_config=generation_config,
            has_default_max_length=has_default_max_length,
            has_default_min_length=has_default_min_length,
            model_input_name=model_input_name,
            inputs_tensor=inputs_tensor,
            input_ids_length=input_ids_length,
        )

        # If the model supports `logits_to_keep` in forward(), set it to 1 to avoid computing the whole
        # logit matrix. This can save a lot of memory during the first forward pass. Note that assisted decoding
        # dynamically overrides this value as it can need more than the last token logits
        if self._supports_logits_to_keep() and "logits_to_keep" not in model_kwargs:
            model_kwargs["logits_to_keep"] = 1

        self._validate_generated_length(generation_config, input_ids_length, has_default_max_length)

        # 7. Prepare the cache.
        # - `model_kwargs` may be updated in place with a cache as defined by the parameters in `generation_config`.
        # - different models have a different cache name expected by the model (default = "past_key_values")
        # - `max_length`, prepared above, is used to determine the maximum cache length
        max_cache_length = generation_config.max_length - 1
        if (
            inputs_tensor.shape[1] != input_ids_length
            and model_input_name == "inputs_embeds"
            and not self.config.is_encoder_decoder
        ):
            max_cache_length += inputs_tensor.shape[1]
        self._prepare_cache_for_generation(
            generation_config, model_kwargs, generation_mode, batch_size, max_cache_length
        )

        if self.device.type != input_ids.device.type:
            warnings.warn(
                "You are calling .generate() with the `input_ids` being on a device type different"
                f" than your model's device. `input_ids` is on {input_ids.device.type}, whereas the model"
                f" is on {self.device.type}. You may experience unexpected behaviors or slower generation."
                " Please make sure that you have put `input_ids` to the"
                f" correct device by calling for example input_ids = input_ids.to('{self.device.type}') before"
                " running `.generate()`.",
                UserWarning,
            )

        # 8. Prepare logits processors and stopping criteria
        prepared_logits_processor = self._get_logits_processor(
            generation_config=generation_config,
            input_ids_seq_length=input_ids_length,
            encoder_input_ids=inputs_tensor,
            prefix_allowed_tokens_fn=prefix_allowed_tokens_fn,
            logits_processor=logits_processor,
            device=inputs_tensor.device,
            model_kwargs=model_kwargs,
            negative_prompt_ids=negative_prompt_ids,
            negative_prompt_attention_mask=negative_prompt_attention_mask,
        )
        prepared_stopping_criteria = self._get_stopping_criteria(
            generation_config=generation_config,
            stopping_criteria=stopping_criteria,
            tokenizer=generation_mode_kwargs.get("tokenizer"),
        )

        # Set model_kwargs `use_cache` so we can use it later in forward runs
        model_kwargs["use_cache"] = generation_config.use_cache

        # 9. Call generation mode
        result = decoding_method(
            self,
            input_ids,
            logits_processor=prepared_logits_processor,
            stopping_criteria=prepared_stopping_criteria,
            generation_config=generation_config,
            **generation_mode_kwargs,
            **model_kwargs,
        )

        return result

    def _has_unfinished_sequences(self, this_peer_finished: bool, synced_gpus: bool, device: torch.device) -> bool:
        """
        Returns whether there are still unfinished sequences in the device. The existence of unfinished sequences is
        fed through `this_peer_finished`. ZeRO stage 3-friendly.
        """
        if synced_gpus:
            # Under synced_gpus the `forward` call must continue until all gpus complete their sequence.
            # The following logic allows an early break if all peers finished generating their sequence
            this_peer_finished_flag = torch.tensor(0.0 if this_peer_finished else 1.0, device=device)
            # send 0.0 if we finished, 1.0 otherwise
            dist.all_reduce(this_peer_finished_flag, op=dist.ReduceOp.SUM)  # type: ignore
            # did all peers finish? the reduced sum will be 0.0 then
            if this_peer_finished_flag.item() == 0.0:
                return False
        elif this_peer_finished:
            return False
        return True

    def heal_tokens(
        self, input_ids: torch.LongTensor, tokenizer: Optional["PreTrainedTokenizerBase"] = None
    ) -> torch.LongTensor:
        r"""
        Generates sequences of token ids for models with a language modeling head.
        Parameters:
            input_ids (`torch.LongTensor`): The sequence used as a prompt for the generation.
            tokenizer (`PreTrainedTokenizerBase`, *optional*): The tokenizer used to decode the input ids.
        Return:
            `torch.LongTensor` where each sequence has its tail token replaced with its appropriate extension.
        """
        if tokenizer is None:
            raise ValueError(
                " When generating with token healing, you must pass the model's tokenizer to the `tokenizer` "
                "argument of `generate`."
            )

        bos_token_id, pad_token_id = tokenizer.bos_token_id, tokenizer.pad_token_id
        vocab_trie = ExtensionsTrie(tokenizer.get_vocab())
        generation_config = GenerationConfig(max_new_tokens=1, pad_token_id=pad_token_id)

        # assumption: leading/trailing whitespace is not meaningful, so the prompts are
        # stripped before re-tokenizing to desensitize generation to whitespace artefacts
        prompts = [p.strip() for p in tokenizer.decode(input_ids, skip_special_tokens=True)]
        input_ids = tokenizer(
            prompts,
            return_tensors="pt",
            padding=True,
        ).input_ids.to(input_ids.device)

        # replace bos with pad to not condition healing on it
        input_ids = torch.where(input_ids == bos_token_id, pad_token_id, input_ids)

        # the latter code assumes the input_ids is not empty, input_id has to be checked if contains elements
        if input_ids.numel() == 0:
            return input_ids

        tail_ids = input_ids[:, -1].tolist()

        # tail tokens are used for a prefix search, thus, whitespaces are replaced with
        # their tokenization (e.g. 'Ġ') to enable search for tokens prefixed with a whitespace
        if tokenizer.convert_tokens_to_ids(" ") is not None:
            space_tok = tokenizer.convert_ids_to_tokens(tokenizer.convert_tokens_to_ids(" "))[0]
            tail_toks = (cast(str, tokenizer.decode(t)).replace(" ", space_tok) for t in tail_ids)
        else:
            tail_toks = (cast(str, tokenizer.decode(t)) for t in tail_ids)

        for batch_idx, (tail_id, tail_tok) in enumerate(zip(tail_ids, tail_toks)):
            batch_ids = input_ids[batch_idx]
            if torch.all(batch_ids == pad_token_id).item():
                continue  # skip empty sequences (all pad ids)

            # apply bias for alternatives (extensions) to the tail token
            """
            seq_bias key has to be tuple with int so have to use
            tokenizer function to convert str to int
			"""
            seq_bias = {
                (tokenizer.convert_tokens_to_ids(alt_tok),): 10.0 for alt_tok in vocab_trie.extensions(prefix=tail_tok)
            }

            if len(seq_bias) == 1:
                continue  # skip if there are no token alternatives to heal with

            # slightly favor original token to limit aggressive healing e.g. 'http' -> 'https'
            seq_bias[(tail_id,)] += 1.0
            generation_config.update(sequence_bias=seq_bias)

            trimmed_ids = batch_ids[:-1]

            """
            the latter code assumes trimmed_ids is not empty
            so have to check the its element count
			"""
            if trimmed_ids.numel() == 0:
                continue

            # if the prompt is a single (non-pad) token, regenerate from bos
            if len(batch_ids[batch_ids != pad_token_id]) == 1:
                trimmed_ids[-1] = bos_token_id

            input_ids[batch_idx] = self.generate(trimmed_ids.unsqueeze(0), generation_config=generation_config)

        return input_ids

    def _sample(
        self: "GenerativePreTrainedModel",
        input_ids: torch.LongTensor,
        logits_processor: LogitsProcessorList,
        stopping_criteria: StoppingCriteriaList,
        generation_config: GenerationConfig,
        synced_gpus: bool = False,
        streamer: Optional["BaseStreamer"] = None,
        **model_kwargs,
    ) -> GenerateNonBeamOutput | torch.LongTensor:
        r"""
        Generates sequences of token ids for models with a language modeling head using **multinomial sampling** and
        can be used for text-decoder, text-to-text, speech-to-text, and vision-to-text models.

        Parameters:
            input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
                The sequence used as a prompt for the generation.
            logits_processor (`LogitsProcessorList`):
                An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
                used to modify the prediction scores of the language modeling head applied at each generation step.
            stopping_criteria (`StoppingCriteriaList`):
                An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
                used to tell if the generation loop should stop.
            generation_config ([`~generation.GenerationConfig`]):
                The generation configuration to be used as parametrization of the decoding method.
            synced_gpus (`bool`):
                Whether to continue running the while loop until max_length (needed to avoid deadlocking with
                `FullyShardedDataParallel` and DeepSpeed ZeRO Stage 3).
            streamer (`BaseStreamer`, *optional*):
                Streamer object that will be used to stream the generated sequences. Generated tokens are passed
                through `streamer.put(token_ids)` and the streamer is responsible for any further processing.
            model_kwargs:
                Additional model specific kwargs will be forwarded to the `forward` function of the model. If model is
                an encoder-decoder model the kwargs should include `encoder_outputs`.

        Return:
            [`~generation.GenerateDecoderOnlyOutput`], [`~generation.GenerateEncoderDecoderOutput`] or `torch.LongTensor`:
            A `torch.LongTensor` containing the generated tokens (default behaviour) or a
            [`~generation.GenerateDecoderOnlyOutput`] if `model.config.is_encoder_decoder=False` and
            `return_dict_in_generate=True` or a [`~generation.GenerateEncoderDecoderOutput`] if
            `model.config.is_encoder_decoder=True`.
        """
        # init values
        pad_token_id = generation_config._pad_token_tensor
        output_attentions = generation_config.output_attentions
        output_hidden_states = generation_config.output_hidden_states
        output_scores = generation_config.output_scores
        output_logits = generation_config.output_logits
        return_dict_in_generate = generation_config.return_dict_in_generate
        has_eos_stopping_criteria = any(hasattr(criteria, "eos_token_id") for criteria in stopping_criteria)
        do_sample = generation_config.do_sample

        # init attention / hidden states / scores tuples
        scores = () if (return_dict_in_generate and output_scores) else None
        raw_logits = () if (return_dict_in_generate and output_logits) else None
        decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
        cross_attentions = () if (return_dict_in_generate and output_attentions) else None
        decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None

        # if model is an encoder-decoder, retrieve encoder attention weights and hidden states
        if return_dict_in_generate and self.config.is_encoder_decoder:
            encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
            encoder_hidden_states = (
                model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
            )

        # keep track of which sequences are already finished
        batch_size = input_ids.shape[0]
        this_peer_finished = False
        unfinished_sequences = torch.ones(batch_size, dtype=torch.long, device=input_ids.device)

        # `pad_token_id` is created on `inputs_tensor.device` in `_prepare_special_tokens`. For multimodal models
        # (e.g. BLIP-2, LLaVA) sharded across devices via `device_map="auto"`, `inputs_tensor` (e.g. `pixel_values`
        # on the vision encoder) and `input_ids` (on the language model) can live on different devices, so we need to
        # realign `pad_token_id` with `input_ids` to avoid cross-device ops below.
        if pad_token_id is not None:
            pad_token_id = pad_token_id.to(input_ids.device)

        model_forward = (
            self.get_compiled_call(generation_config.compile_config)
            if self._valid_auto_compile_criteria(model_kwargs, generation_config)
            else self.__call__
        )

        prefill_consumed = False
        outputs = self._prefill(
            input_ids,
            generation_config,
            model_kwargs,
            is_first_iteration=not generation_config.is_assistant,
        )

        while self._has_unfinished_sequences(this_peer_finished, synced_gpus, device=input_ids.device):
            if prefill_consumed:
                next_sequence_length = 1 if model_kwargs["use_cache"] else None
                model_inputs = self.prepare_inputs_for_generation(
                    input_ids, next_sequence_length=next_sequence_length, **model_kwargs
                )
                with self._optimize_model_for_decode():
                    outputs = model_forward(**model_inputs, return_dict=True)
            prefill_consumed = True
            model_kwargs = self._update_model_kwargs_for_generation(
                outputs,
                model_kwargs,
                is_encoder_decoder=self.config.is_encoder_decoder,
            )
            if synced_gpus and this_peer_finished:
                continue

            # Copy is needed to avoid keeping a hanging ref to outputs.logits which may be very large for first iteration
            # (the clone itself is always small)
            next_token_logits = outputs.logits[:, -1, :].to(copy=True, dtype=torch.float32, device=input_ids.device)

            # pre-process distribution
            next_token_scores = logits_processor(input_ids, next_token_logits)

            # Store scores, attentions and hidden_states when required
            if return_dict_in_generate:
                if output_scores:
                    scores += (next_token_scores,)
                if output_logits:
                    raw_logits += (next_token_logits,)
                if output_attentions:
                    decoder_attentions += (
                        (outputs.decoder_attentions,) if self.config.is_encoder_decoder else (outputs.attentions,)
                    )
                    if self.config.is_encoder_decoder:
                        cross_attentions += (outputs.cross_attentions,)

                if output_hidden_states:
                    decoder_hidden_states += (
                        (outputs.decoder_hidden_states,)
                        if self.config.is_encoder_decoder
                        else (outputs.hidden_states,)
                    )

            # token selection
            if do_sample:
                probs = nn.functional.softmax(next_token_scores, dim=-1)
                # TODO (joao): this OP throws "skipping cudagraphs due to ['incompatible ops']", find solution
                next_tokens = torch.multinomial(probs, num_samples=1).squeeze(1)
            else:
                next_tokens = torch.argmax(next_token_scores, dim=-1)

            # finished sentences should have their next token be a padding token
            if has_eos_stopping_criteria:
                next_tokens = next_tokens * unfinished_sequences + pad_token_id * (1 - unfinished_sequences)

            # update generated ids, model inputs, and length for next step
            input_ids = torch.cat([input_ids, next_tokens[:, None]], dim=-1)
            if streamer is not None:
                streamer.put(next_tokens.cpu())

            unfinished_sequences = unfinished_sequences & ~stopping_criteria(input_ids, scores)
            this_peer_finished = unfinished_sequences.max() == 0

            # This is needed to properly delete outputs.logits which may be very large for first iteration
            # Otherwise a reference to outputs is kept which keeps the logits alive in the next iteration
            del outputs

        if streamer is not None:
            streamer.end()

        if return_dict_in_generate:
            cache = None
            if any(cache_key in model_kwargs for cache_key in ALL_CACHE_NAMES):
                cache_key = next(cache_key for cache_key in ALL_CACHE_NAMES if cache_key in model_kwargs)
                cache = model_kwargs[cache_key]
            if self.config.is_encoder_decoder:
                return GenerateEncoderDecoderOutput(
                    sequences=input_ids,
                    scores=scores,
                    logits=raw_logits,
                    encoder_attentions=encoder_attentions,
                    encoder_hidden_states=encoder_hidden_states,
                    decoder_attentions=decoder_attentions,
                    cross_attentions=cross_attentions,
                    decoder_hidden_states=decoder_hidden_states,
                    past_key_values=cache,
                )
            else:
                return GenerateDecoderOnlyOutput(
                    sequences=input_ids,
                    scores=scores,
                    logits=raw_logits,
                    attentions=decoder_attentions,
                    hidden_states=decoder_hidden_states,
                    past_key_values=cache,
                )
        else:
            return input_ids

    @staticmethod
    def _flatten_beam_dim(tensor: torch.Tensor) -> torch.Tensor:
        """[batch_size, num_beams, ...] -> [batch_size * num_beams, ...]"""
        shape = list(tensor.shape)
        return torch.reshape(tensor, [shape[0] * shape[1]] + shape[2:])

    @staticmethod
    def _unflatten_beam_dim(tensor: torch.Tensor, batch_size: int, num_beams: int) -> torch.Tensor:
        """[batch_size * num_beams, ...] -> [batch_size, num_beams, ...]"""
        shape = list(tensor.shape)
        return torch.reshape(tensor, [batch_size, num_beams] + shape[1:])

    @staticmethod
    def _gather_beams(tensor: torch.Tensor, beam_indices: torch.Tensor) -> torch.Tensor:
        """
        Gathers the beam slices indexed by beam_indices into new beam array.

        Args:
            tensor (`torch.Tensor`): A tensor containing data to be gathered. The tensor is a 2D or a 3D tensor
                with the two first dimensions depicting the batch and the beam dimensions.
            beam_indices (`torch.Tensor` of shape `(batch_size, num_beams_to_select)`): The indices of the beams to
                select .

        Returns:
            A tensor with the selected beams
        """
        # `take_along_dim` requires its indices arg to have the same number of dims as `input`
        while len(beam_indices.shape) < len(tensor.shape):
            beam_indices = beam_indices.unsqueeze(-1)
        gathered_tensor = torch.take_along_dim(input=tensor, indices=beam_indices, dim=1)
        return gathered_tensor

    @staticmethod
    def _check_early_stop_heuristic(
        is_early_stop_heuristic_unsatisfied: torch.Tensor,
        running_beam_scores: torch.Tensor,
        beam_scores: torch.Tensor,
        is_sent_finished: torch.Tensor,
        cur_len: int,
        max_length: int,
        decoder_prompt_len: int,
        early_stopping: bool | str,
        length_penalty: float,
    ):
        """
        Determine whether early stopping is possible by checking if the best possible score of running beams
        could still improve upon the finished ones.

        Mechanism:
        - Without a length penalty, beam scores typically decrease as more tokens are generated.
        So, if the *best possible* score from any running beam is already worse than the *worst* finished beam,
        we can safely stop early.
        - With a length penalty, scores may increase with longer sequences. In this case, we use heuristics
        to estimate the best possible score — though this estimate may not always be correct — and stop
        if no further improvement seems likely.

        We apply different heuristics depending on the value of `early_stopping`:
        1. `early_stopping == False`:
        -> Use a heuristic that assumes the best score comes from the current length minus the decoder prompt length.
        -> See detailed discussion: https://github.com/huggingface/transformers/pull/20901#issuecomment-1369845565

        2. `early_stopping == "never"`:
        -> Estimate the best score using either `max_length` or `cur_len`, depending on the sign of `length_penalty`.
        -> A positive length penalty favors longer sequences, so we use `max_length` in that case.

        NOTE: the canonical beam search implementation can be replicated with `early_stopping="never"` and
        `length_penalty=0.0`, which are NOT the default flags. The default behavior was empirically found to produce
        better sequences (prior to 2022), and changing it is BC breaking.
        """
        if early_stopping == "never" and length_penalty > 0.0:
            best_hypothetical_length = max_length - decoder_prompt_len
        else:
            best_hypothetical_length = cur_len - decoder_prompt_len
        best_possible_running_score = running_beam_scores[:, :1] / (best_hypothetical_length**length_penalty)
        worst_finished_score = torch.where(is_sent_finished, torch.min(beam_scores, dim=1, keepdim=True)[0], -1.0e9)
        return is_early_stop_heuristic_unsatisfied & torch.any(
            best_possible_running_score > worst_finished_score, dim=-1, keepdim=True
        )

    @staticmethod
    def _beam_search_has_unfinished_sequences(
        is_early_stop_heuristic_unsatisfied: torch.Tensor,
        is_sent_finished: torch.Tensor,
        next_token_hits_stopping_criteria: torch.Tensor,
        early_stopping: bool | str,
    ):
        """
        Beam Search stopping condition -- halts the generation loop if any of these conditions becomes False
        """
        # a. Can the open beams improve the top completed scores?
        improvement_possible = torch.any(is_early_stop_heuristic_unsatisfied)

        # b. Is there still a beam without fully completed sequences? This is only relevant if early_stopping is
        # enabled, where we want to finish as soon as all beams have a completed sequence.
        exists_open_beam = ~(torch.all(is_sent_finished) & (early_stopping is True))

        # c. Have we hit a stopping criteria with all running sequences and have no way to continue? e.g. we have
        # reached `max_length``
        valid_continuations = ~torch.all(next_token_hits_stopping_criteria)

        return improvement_possible & exists_open_beam & valid_continuations

    def _get_top_k_continuations(
        self,
        accumulated_log_probs: torch.Tensor,
        running_sequences: torch.Tensor,
        running_beam_indices: torch.Tensor,
        cur_len: int,
        decoder_prompt_len: int,
        do_sample: bool,
        beams_to_keep: int,
        num_beams: int,
        vocab_size: int,
        batch_size: int,
    ) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
        """
        Get top-K continuations given the accumulated log probs on the next token.

        A few notes to understand what's going on:
        1. Each item in batch has `num_beams` * `vocab_size` candidate continuations. For each item, get the
        top K [K = (number of EOS tokens + 1) * `num_beams`] candidates with the highest accumulated
        log-probabilities, or sample them without replacement using the accumulated scores
        2. We gather the top K (as opposed to `num_beams`, or any number lower than K) here so that we have at
        least `num_beams` sequences remaining to continue the live beam search.
        3. Note that other stopping criteria might result in impossible to continue beams, i.e. all continuations
        selected in this step hit the stopping criteria.
        """
        # TODO (joao): This function should take an optional beam scorer function, to manipulate the scores after
        # token selection. The function should be an argument exposed, so that custom scoring functions can be
        # defined.

        # Gather the top K scores from _all_ beams.
        if do_sample:
            topk_indices = torch.multinomial(
                nn.functional.softmax(accumulated_log_probs, dim=-1), num_samples=beams_to_keep
            )
            topk_log_probs = torch.gather(input=accumulated_log_probs, dim=1, index=topk_indices)
        else:
            topk_log_probs, topk_indices = torch.topk(accumulated_log_probs, k=beams_to_keep)

        # Gather K top beams, recover the beam index by floor division and token id by modulo division
        topk_current_beam_indices = topk_indices // vocab_size
        topk_running_beam_indices = self._gather_beams(running_beam_indices, topk_current_beam_indices)
        topk_running_sequences = self._gather_beams(running_sequences, topk_current_beam_indices)
        topk_ids = topk_indices % vocab_size

        # Update sequences for the K top-k new sequences.
        topk_running_sequences[:, :, cur_len] = topk_ids

        # we want to store the beam indices with batch information -> real beam index = beam index % num beams
        batch_offset = torch.arange(batch_size, device=topk_ids.device).view(-1, 1) * num_beams
        batch_modified_indices = topk_current_beam_indices + batch_offset
        topk_running_beam_indices[:, :, cur_len - decoder_prompt_len] = batch_modified_indices

        return topk_log_probs, topk_running_sequences, topk_running_beam_indices

    def _get_running_beams_for_next_iteration(
        self,
        topk_log_probs: torch.Tensor,
        topk_running_sequences: torch.Tensor,
        topk_running_beam_indices: torch.Tensor,
        next_token_hits_stopping_criteria: torch.Tensor,
        num_beams: int,
    ) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
        """
        Given the top-K continuations, their scores, and whether they hit a stopping criteria, select the
        best non-finished beams to continue beam search in the next iteration.
        """
        # To prevent these just finished sequences from being used in subsequent iterations, set their log probs
        # to a very large negative value
        topk_running_log_probs = topk_log_probs + next_token_hits_stopping_criteria.to(torch.float32) * -1.0e9

        next_topk_indices = torch.topk(topk_running_log_probs, k=num_beams)[1]
        running_sequences = self._gather_beams(topk_running_sequences, next_topk_indices)
        running_beam_scores = self._gather_beams(topk_running_log_probs, next_topk_indices)
        running_beam_indices = self._gather_beams(topk_running_beam_indices, next_topk_indices)
        return running_sequences, running_beam_scores, running_beam_indices

    def _update_finished_beams(
        self,
        sequences: torch.Tensor,
        topk_running_sequences: torch.Tensor,
        beam_scores: torch.Tensor,
        topk_log_probs: torch.Tensor,
        beam_indices: torch.Tensor,
        topk_running_beam_indices: torch.Tensor,
        is_early_stop_heuristic_unsatisfied: torch.Tensor,
        is_sent_finished: torch.Tensor,
        next_token_hits_stopping_criteria: torch.Tensor,
        top_num_beam_mask: torch.Tensor,
        num_beams: int,
        cur_len: int,
        decoder_prompt_len: int,
        length_penalty: float,
        early_stopping: bool | str,
    ) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor, torch.Tensor]:
        """
        Updates the finished beams if (and only if) there are new completed sequences that have a higher score than
        the current finished sequences.
        """
        # Only the top `num_beam` sequences can be considered for the final returned sequences. Remember: the
        # remaining sequences only exist as a backup to ensure that we have at least `num_beams` sequences to
        # continue.
        did_top_num_beams_just_finished = next_token_hits_stopping_criteria & top_num_beam_mask[None, :]

        # Further process topk logits for the finished beams
        # - add length penalty
        topk_log_probs = topk_log_probs / ((cur_len + 1 - decoder_prompt_len) ** length_penalty)
        # - make sure no scores can be added anymore if beam is full and early stopping is on
        beams_in_batch_are_full = torch.all(is_sent_finished, axis=-1, keepdims=True) & (early_stopping is True)
        topk_log_probs += beams_in_batch_are_full.to(torch.float32) * -1.0e9
        # - make sure no scores can be added anymore if improvement is not possible
        topk_log_probs += (~is_early_stop_heuristic_unsatisfied).to(torch.float32) * -1.0e9

        # - make sure still running sequences cannot be chosen as finalized beam
        topk_log_probs += (~did_top_num_beams_just_finished) * -1.0e9

        # Get finalized  `num_beam` sequences for the next generation step -- combine the previous finalized
        # data with the new finalized sequences (if any, non-finalized sequences have a very large negative score
        # in this step), and keep the best `num_beams` sequences.
        merged_sequences = torch.cat((sequences, topk_running_sequences), dim=1)
        merged_scores = torch.cat((beam_scores, topk_log_probs), dim=1)
        merged_beam_indices = torch.cat((beam_indices, topk_running_beam_indices), dim=1)
        merged_is_sent_finished = torch.cat((is_sent_finished, did_top_num_beams_just_finished), dim=1)
        topk_merged_indices = torch.topk(merged_scores, k=num_beams)[1]
        sequences = self._gather_beams(merged_sequences, topk_merged_indices)
        beam_scores = self._gather_beams(merged_scores, topk_merged_indices)
        beam_indices = self._gather_beams(merged_beam_indices, topk_merged_indices)
        is_sent_finished = self._gather_beams(merged_is_sent_finished, topk_merged_indices)
        return sequences, beam_scores, beam_indices, is_sent_finished

    # end of auxiliary functions for beam search

    def _beam_search(
        self: "GenerativePreTrainedModel",
        input_ids: torch.LongTensor,
        logits_processor: LogitsProcessorList,
        stopping_criteria: StoppingCriteriaList,
        generation_config: GenerationConfig,
        synced_gpus: bool = False,
        **model_kwargs,
    ) -> GenerateBeamOutput | torch.LongTensor:
        r"""
        Generates sequences of token ids for models with a language modeling head using **beam search decoding** and
        can be used for text-decoder, text-to-text, speech-to-text, and vision-to-text models.

        If it's the first time you're diving into Beam Search, we recommend you read the following blog post:
        https://huggingface.co/blog/how-to-generate (especially the beam search section).

        You can recompute the sequence scores from the individual scores using the `compute_transition_scores` function
        (https://huggingface.co/docs/transformers/main_classes/text_generation#transformers.GenerationMixin.compute_transition_scores)

        Parameters:
            input_ids (`torch.LongTensor` of shape `(batch_size*num_beams, sequence_length)`):
                The sequence used as a prompt for the generation.
            logits_processor (`LogitsProcessorList`):
                An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
                used to modify the prediction scores of the language modeling head applied at each generation step.
            stopping_criteria (`StoppingCriteriaList`:
                An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
                used to tell if the generation loop should stop.
            generation_config ([`~generation.GenerationConfig`]):
                The generation configuration to be used as parametrization of the decoding method.
            synced_gpus (`bool`):
                Whether to continue running the while loop until max_length (needed to avoid deadlocking with
                `FullyShardedDataParallel` and DeepSpeed ZeRO Stage 3).
            model_kwargs:
                Additional model specific kwargs will be forwarded to the `forward` function of the model. If model is
                an encoder-decoder model the kwargs should include `encoder_outputs`.

        Return:
            [`generation.GenerateBeamDecoderOnlyOutput`], [`~generation.GenerateBeamEncoderDecoderOutput`] or
            `torch.LongTensor`: A `torch.LongTensor` containing the generated tokens (default behaviour) or a
            [`~generation.GenerateBeamDecoderOnlyOutput`] if `model.config.is_encoder_decoder=False` and
            `return_dict_in_generate=True` or a [`~generation.GenerateBeamEncoderDecoderOutput`] if
            `model.config.is_encoder_decoder=True`.
        """
        # 1. init beam_search values
        pad_token_id = generation_config._pad_token_tensor
        eos_token_id = generation_config._eos_token_tensor
        output_attentions = generation_config.output_attentions
        output_hidden_states = generation_config.output_hidden_states
        output_scores = generation_config.output_scores
        output_logits = generation_config.output_logits
        return_dict_in_generate = generation_config.return_dict_in_generate
        do_sample = generation_config.do_sample
        early_stopping = generation_config.early_stopping
        length_penalty = generation_config.length_penalty
        max_length = generation_config.max_length
        num_beams = generation_config.num_beams
        num_return_sequences = generation_config.num_return_sequences

        batch_size_unflattened, cur_len = input_ids.shape[:2]
        batch_size = batch_size_unflattened // num_beams
        # TODO (joao): standardize special cases
        if self.__class__.__name__ == "MoshiDepthDecoder":
            vocab_size = self.config.audio_vocab_size
        elif self.__class__.__name__ == "ImageGPTForCausalImageModeling":
            vocab_size = self.get_output_embeddings().out_features
        elif self.__class__.__name__ == "BarkSemanticModel":
            vocab_size = self.config.output_vocab_size
        else:
            vocab_size = self.config.get_text_config().vocab_size
        decoder_prompt_len = cur_len
        this_peer_finished = False

        # At each beam search step, we want to keep top K [K = (number of EOS tokens + 1) * `num_beams`] candidates
        # with the highest log-probabilities, or sample K continuations without replacement. We gather the top K
        # (as opposed to `num_beams`, or any number lower than K) so that we have at least `num_beams` sequences
        # non-finished to continue the live beam search, in case the top `num_beams` all select an EOS token.
        n_eos_tokens = eos_token_id.shape[0] if eos_token_id is not None else 0
        beams_to_keep = max(2, 1 + n_eos_tokens) * num_beams
        top_num_beam_mask = torch.cat(
            (torch.ones((num_beams), dtype=torch.bool), torch.zeros((beams_to_keep - num_beams), dtype=torch.bool)),
            dim=0,
        ).to(input_ids.device)

        # (joao) feature lost in the refactor. Probably won't implement, hurts readability with minimal gains (there
        # are newer low-memory alternatives like the offloaded cache)
        sequential = generation_config.low_memory
        if sequential:
            raise ValueError(
                "`low_memory=True` is not supported after the beam search refactor. Please check the discussion in "
                "#35802 *after the PR got merged*, and add a comment there if your questions are not yet answered."
            )

        # 2. init output tuples
        all_scores = () if (return_dict_in_generate and output_scores) else None
        raw_logits = () if (return_dict_in_generate and output_logits) else None
        beam_indices = () if (return_dict_in_generate and output_logits) else None
        decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
        cross_attentions = () if (return_dict_in_generate and output_attentions) else None
        decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None

        # if model is an encoder-decoder, retrieve encoder attention weights and hidden states
        if return_dict_in_generate and self.config.is_encoder_decoder:
            encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
            encoder_hidden_states = (
                model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
            )

        # 3. init running tensors and static-shaped placeholders

        # per batch, beam-item holding current token in loop and completed sequences
        output_fill_value = pad_token_id or eos_token_id[0] if eos_token_id is not None else -1
        running_sequences = torch.full(
            (batch_size, num_beams, max_length),
            fill_value=output_fill_value,
            dtype=torch.int64,
            device=input_ids.device,
        )
        running_sequences[:, :, :cur_len] = self._unflatten_beam_dim(input_ids, batch_size, num_beams)
        sequences = running_sequences.detach().clone()

        # per batch, beam-item score, logprobs
        # initialise score of first beam with 0 and the rest with -1e9. This makes sure that only tokens
        # of the first beam are considered to avoid sampling the exact same tokens across all beams.
        running_beam_scores = torch.zeros((batch_size, num_beams), dtype=torch.float, device=input_ids.device)
        running_beam_scores[:, 1:] = -1e9
        beam_scores = torch.full((batch_size, num_beams), fill_value=-1e9, dtype=torch.float, device=input_ids.device)

        # per batch, beam-item state bit indicating if sentence has finished.
        is_sent_finished = torch.zeros((batch_size, num_beams), dtype=torch.bool, device=input_ids.device)

        # per batch state bit indicating if there is a possibility to improve the best finished sentence.
        is_early_stop_heuristic_unsatisfied = torch.ones((batch_size, 1), dtype=torch.bool, device=input_ids.device)

        # per batch, beam-item state bit indicating if there are valid continuations.
        next_token_hits_stopping_criteria = torch.zeros(
            (batch_size, num_beams), dtype=torch.bool, device=input_ids.device
        )

        # per batch selected beam indices
        running_beam_indices = torch.full(
            (batch_size, num_beams, max_length - cur_len), fill_value=-1, dtype=torch.int32, device=input_ids.device
        )
        beam_indices = running_beam_indices.detach().clone()

        flat_running_sequences = input_ids
        prefill_consumed = False
        model_outputs = self._prefill(
            input_ids,
            generation_config,
            model_kwargs,
            is_first_iteration=not generation_config.is_assistant,
        )

        # 4. run the generation loop
        while self._has_unfinished_sequences(this_peer_finished, synced_gpus, device=input_ids.device):
            if prefill_consumed:
                # a. Forward current tokens, obtain the logits
                flat_running_sequences = self._flatten_beam_dim(running_sequences[:, :, :cur_len])
                next_sequence_length = 1 if model_kwargs["use_cache"] else None
                model_inputs = self.prepare_inputs_for_generation(
                    flat_running_sequences, next_sequence_length=next_sequence_length, **model_kwargs
                )
                model_outputs = self(**model_inputs, return_dict=True)
            prefill_consumed = True

            # synced_gpus: don't waste resources running the code we don't need; kwargs must be updated before skipping
            model_kwargs = self._update_model_kwargs_for_generation(
                model_outputs,
                model_kwargs,
                is_encoder_decoder=self.config.is_encoder_decoder,
            )
            if synced_gpus and this_peer_finished:
                continue

            # Copy is needed to avoid keeping a hanging ref
            logits = model_outputs.logits[:, -1, :].to(copy=True, dtype=torch.float32, device=input_ids.device)

            # b. Compute log probs -- get log probabilities from logits, process logits with processors (*e.g.*
            # `temperature`, ...), and add new logprobs to existing running logprobs scores.
            log_probs = nn.functional.log_softmax(logits, dim=-1)
            log_probs = logits_processor(flat_running_sequences, log_probs)

            # Store logits, attentions and hidden_states when required
            if return_dict_in_generate:
                if output_logits:
                    raw_logits += (logits.clone(),)
                if return_dict_in_generate and output_scores:
                    all_scores += (log_probs.clone(),)

                if output_attentions:
                    decoder_attentions += (
                        (model_outputs.decoder_attentions,)
                        if self.config.is_encoder_decoder
                        else (model_outputs.attentions,)
                    )
                    if self.config.is_encoder_decoder:
                        cross_attentions += (model_outputs.cross_attentions,)

                if output_hidden_states:
                    decoder_hidden_states += (
                        (model_outputs.decoder_hidden_states,)
                        if self.config.is_encoder_decoder
                        else (model_outputs.hidden_states,)
                    )

            # This is needed to properly delete logits which may be very large for first iteration
            # Otherwise a reference to outputs is kept which keeps the logits alive in the next iteration
            del model_outputs

            log_probs = self._unflatten_beam_dim(log_probs, batch_size, num_beams)
            log_probs = log_probs + running_beam_scores[:, :, None]
            log_probs = torch.reshape(log_probs, (batch_size, num_beams * vocab_size))

            # c. Retrieve top-K continuations, i.e. select the next token (greedy or sampling) and then keep the best
            # continuations among all beams based on the accumulated scores.
            topk_log_probs, topk_running_sequences, topk_running_beam_indices = self._get_top_k_continuations(
                accumulated_log_probs=log_probs,
                running_sequences=running_sequences,
                running_beam_indices=running_beam_indices,
                cur_len=cur_len,
                decoder_prompt_len=decoder_prompt_len,
                do_sample=do_sample,
                beams_to_keep=beams_to_keep,
                num_beams=num_beams,
                vocab_size=vocab_size,
                batch_size=batch_size,
            )

            # d. Check which running sequences have finished
            next_token_hits_stopping_criteria = stopping_criteria(
                self._flatten_beam_dim(topk_running_sequences[:, :, : cur_len + 1]),  # remove unfilled token indexes
                all_scores,
            )
            next_token_hits_stopping_criteria = self._unflatten_beam_dim(
                next_token_hits_stopping_criteria, batch_size, beams_to_keep
            )

            # e. Get the non-finished running `num_beams` sequences for the next generation step
            running_sequences, running_beam_scores, running_beam_indices = self._get_running_beams_for_next_iteration(
                topk_log_probs=topk_log_probs,
                topk_running_sequences=topk_running_sequences,
                topk_running_beam_indices=topk_running_beam_indices,
                next_token_hits_stopping_criteria=next_token_hits_stopping_criteria,
                num_beams=num_beams,
            )

            # f. Update the completed beams if a new high score in a finished sequence is found
            sequences, beam_scores, beam_indices, is_sent_finished = self._update_finished_beams(
                sequences=sequences,
                topk_running_sequences=topk_running_sequences,
                beam_scores=beam_scores,
                topk_log_probs=topk_log_probs,
                beam_indices=beam_indices,
                topk_running_beam_indices=topk_running_beam_indices,
                is_early_stop_heuristic_unsatisfied=is_early_stop_heuristic_unsatisfied,
                is_sent_finished=is_sent_finished,
                next_token_hits_stopping_criteria=next_token_hits_stopping_criteria,
                top_num_beam_mask=top_num_beam_mask,
                num_beams=num_beams,
                cur_len=cur_len,
                decoder_prompt_len=decoder_prompt_len,
                length_penalty=length_penalty,
                early_stopping=early_stopping,
            )

            # g. Prepare remaining data for the next iteration, including computing the stopping condition for
            # beam search as a whole (as opposed to individual beams, i.e. `stopping_criteria`)

            # pluck the cache from the beam indices that will be used in the next iteration
            # NOTE: we need to check if `self._reorder_cache` exists for special models like RAG, RecurrentGemma etc.
            if any(cache_key in model_kwargs for cache_key in ALL_CACHE_NAMES):
                cache_key = next(cache_key for cache_key in ALL_CACHE_NAMES if cache_key in model_kwargs)
                beam_idx = self._flatten_beam_dim(running_beam_indices[..., cur_len - decoder_prompt_len])
                if hasattr(self, "_reorder_cache"):
                    model_kwargs[cache_key] = self._reorder_cache(model_kwargs[cache_key], beam_idx)
                elif hasattr(model_kwargs[cache_key], "reorder_cache"):
                    model_kwargs[cache_key].reorder_cache(beam_idx)
                else:
                    raise ValueError(
                        f"{self.__class__.__name__} cannot use beam search with a cache currently, as the cache cannot be reordered"
                    )

            cur_len = cur_len + 1
            is_early_stop_heuristic_unsatisfied = self._check_early_stop_heuristic(
                is_early_stop_heuristic_unsatisfied=is_early_stop_heuristic_unsatisfied,
                running_beam_scores=running_beam_scores,
                beam_scores=beam_scores,
                is_sent_finished=is_sent_finished,
                cur_len=cur_len,
                max_length=max_length,
                decoder_prompt_len=decoder_prompt_len,
                early_stopping=early_stopping,
                length_penalty=length_penalty,
            )
            this_peer_finished = not self._beam_search_has_unfinished_sequences(
                is_early_stop_heuristic_unsatisfied,
                is_sent_finished,
                next_token_hits_stopping_criteria,
                early_stopping,
            )

        # 5. prepare outputs
        # Take best beams for each batch (the score is sorted in descending order)
        sequences = self._flatten_beam_dim(sequences[:, :num_return_sequences, :])
        beam_scores = self._flatten_beam_dim(beam_scores[:, :num_return_sequences])
        beam_indices = self._flatten_beam_dim(beam_indices[:, :num_return_sequences, :])

        # Crop the static-shaped tensors to the actual size.
        # `beam_indices` is initialized with -1s, and is updated with the beam index of the generated token at each
        # step. We can use it to detect the generated length, which may be != `cur_len`  (e.g. selected beam is from a
        # previous decoding iteration)
        max_generated_length = ((beam_indices + 1).bool()).sum(dim=1).max()
        output_length = decoder_prompt_len + max_generated_length
        sequences = sequences[:, :output_length]
        beam_indices = beam_indices[:, :max_generated_length]

        if return_dict_in_generate:
            if not output_scores:
                beam_scores = None

            cache = None
            if any(cache_key in model_kwargs for cache_key in ALL_CACHE_NAMES):
                cache_key = next(cache_key for cache_key in ALL_CACHE_NAMES if cache_key in model_kwargs)
                cache = model_kwargs[cache_key]

            if self.config.is_encoder_decoder:
                return GenerateBeamEncoderDecoderOutput(
                    sequences=sequences,
                    sequences_scores=beam_scores,
                    scores=all_scores,
                    logits=raw_logits,
                    beam_indices=beam_indices,
                    encoder_attentions=encoder_attentions,
                    encoder_hidden_states=encoder_hidden_states,
                    decoder_attentions=decoder_attentions,
                    cross_attentions=cross_attentions,
                    decoder_hidden_states=decoder_hidden_states,
                    past_key_values=cache,
                )
            else:
                return GenerateBeamDecoderOnlyOutput(
                    sequences=sequences,
                    sequences_scores=beam_scores,
                    scores=all_scores,
                    logits=raw_logits,
                    beam_indices=beam_indices,
                    attentions=decoder_attentions,
                    hidden_states=decoder_hidden_states,
                    past_key_values=cache,
                )
        else:
            return sequences

    def _assisted_decoding(
        self: "GenerativePreTrainedModel",
        input_ids: torch.LongTensor,
        logits_processor: LogitsProcessorList,
        stopping_criteria: StoppingCriteriaList,
        generation_config: GenerationConfig,
        synced_gpus: bool = False,
        streamer: Optional["BaseStreamer"] = None,
        inputs_tensor: torch.FloatTensor | None = None,
        assistant_model: Optional["PreTrainedModel"] = None,
        assistant_tokenizer: Optional["PreTrainedTokenizerBase"] = None,
        tokenizer: Optional["PreTrainedTokenizerBase"] = None,
        **model_kwargs,
    ) -> GenerateNonBeamOutput | torch.LongTensor:
        r"""
        Generates sequences of token ids for models with a language modeling head using **greedy decoding** or
        **sample** (depending on `do_sample`), assisted by candidate sequences. Assisted generation is an example of a
        candidate decoding strategy. Can be used for text-decoder, text-to-text, speech-to-text, and vision-to-text
        models.

        Parameters:
            input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
                The sequence used as a prompt for the generation.
            logits_processor (`LogitsProcessorList`):
                An instance of [`LogitsProcessorList`]. List of instances of class derived from [`LogitsProcessor`]
                used to modify the prediction scores of the language modeling head applied at each generation step.
            stopping_criteria (`StoppingCriteriaList`):
                An instance of [`StoppingCriteriaList`]. List of instances of class derived from [`StoppingCriteria`]
                used to tell if the generation loop should stop.
            generation_config ([`~generation.GenerationConfig`]):
                The generation configuration to be used as parametrization of the decoding method.
            synced_gpus (`bool`):
                Whether to continue running the while loop until max_length (needed to avoid deadlocking with
                `FullyShardedDataParallel` and DeepSpeed ZeRO Stage 3).
            streamer (`BaseStreamer`, *optional*):
                Streamer object that will be used to stream the generated sequences. Generated tokens are passed
                through `streamer.put(token_ids)` and the streamer is responsible for any further processing.
            inputs_tensor (`torch.FloatTensor`, *optional*):
                The input tensor for generation. For decoder models, usually `input_ids`. For encoder-decoder models,
                the tensor that produced `model_kwargs["encoder_outputs"]`.
            assistant_model (`PreTrainedModel`, *optional*):
                The model used to assist the generation process. If not provided, the main model will be used.
            assistant_tokenizer (`PreTrainedTokenizerBase`, *optional*):
                The tokenizer used for the assistant model. If not provided, the token space is assumed to be the same.
            tokenizer (`PreTrainedTokenizerBase`, *optional*):
                The tokenizer used for the main model. If not provided, the token space is assumed to be the same.
            model_kwargs:
                Additional model specific keyword arguments will be forwarded to the `forward` function of the model.
                If model is an encoder-decoder model the kwargs should include `encoder_outputs`.

        Return:
            [`~generation.GenerateDecoderOnlyOutput`], [`~generation.GenerateEncoderDecoderOutput`] or
            `torch.LongTensor`: A `torch.LongTensor` containing the generated tokens (default behaviour) or a
            [`~generation.GenerateDecoderOnlyOutput`] if `model.config.is_encoder_decoder=False` and
            `return_dict_in_generate=True` or a [`~generation.GenerateEncoderDecoderOutput`] if
            `model.config.is_encoder_decoder=True`.
        """
        # The cache must be dynamic for assisted generation, and the check must happen AFTER preparing cache
        if not model_kwargs["use_cache"]:
            raise ValueError("assisted generate requires `use_cache=True`")
        if (
            generation_config.cache_implementation in ["static", "hybrid", "sliding_window"]
            or type(model_kwargs.get("past_key_values")) is StaticCache
        ):
            raise ValueError("assisted generate is not supported with Static cache classes`")
        # Get the candidate generator, given the parameterization
        candidate_generator = self._get_candidate_generator(
            generation_config=generation_config,
            input_ids=input_ids,
            inputs_tensor=inputs_tensor,
            assistant_model=assistant_model,
            logits_processor=logits_processor,
            target_tokenizer=tokenizer,
            assistant_tokenizer=assistant_tokenizer,
            model_kwargs=model_kwargs,
        )
        # init values
        do_sample = generation_config.do_sample
        output_attentions = generation_config.output_attentions
        output_hidden_states = generation_config.output_hidden_states
        output_scores = generation_config.output_scores
        output_logits = generation_config.output_logits
        return_dict_in_generate = generation_config.return_dict_in_generate

        # init attention / hidden states / scores tuples
        scores = () if (return_dict_in_generate and output_scores) else None
        raw_logits = () if (return_dict_in_generate and output_logits) else None
        decoder_attentions = () if (return_dict_in_generate and output_attentions) else None
        cross_attentions = () if (return_dict_in_generate and output_attentions) else None
        decoder_hidden_states = () if (return_dict_in_generate and output_hidden_states) else None

        # if model is an encoder-decoder, retrieve encoder attention weights and hidden states
        if return_dict_in_generate and self.config.is_encoder_decoder:
            encoder_attentions = model_kwargs["encoder_outputs"].get("attentions") if output_attentions else None
            encoder_hidden_states = (
                model_kwargs["encoder_outputs"].get("hidden_states") if output_hidden_states else None
            )

        # keep track of which sequences are already finished
        batch_size, cur_len = input_ids.shape[:2]
        if batch_size > 1:
            raise ValueError("assisted generate is only supported for batch_size = 1")
        unfinished_sequences = torch.ones(batch_size, dtype=torch.long, device=input_ids.device)

        this_peer_finished = False
        is_first_iteration = True  # to preserve the same API in the output as other generation methods
        outputs = None
        n_matches = 0
        while self._has_unfinished_sequences(this_peer_finished, synced_gpus, device=input_ids.device):
            cur_len = input_ids.shape[1]

            #  1. Fetch candidate sequences from a `CandidateGenerator` and move to the correct device
            if candidate_generator.requires_model_outputs:
                candidate_input_ids, candidate_logits = candidate_generator.get_candidates(
                    input_ids,
                    model_kwargs=model_kwargs,
                    model_outputs=outputs,
                    is_first_iteration=is_first_iteration,
                    n_last_matches=n_matches,
                )
            else:
                candidate_input_ids, candidate_logits = candidate_generator.get_candidates(input_ids)
            candidate_input_ids = candidate_input_ids.to(self.device)
            if candidate_logits is not None:
                candidate_logits = candidate_logits.to(self.device)

            candidate_length = candidate_input_ids.shape[1] - input_ids.shape[1]
            is_done_candidate = stopping_criteria(candidate_input_ids, None)

            # 2. Use the original model to obtain the next token logits given the candidate sequence. We obtain
            # `candidate_length + 1` relevant logits from this process: in the event that all candidates are correct,
            # we use this forward pass to also pick the subsequent logits in the original model.

            # 2.1. Prepare the model inputs
            candidate_kwargs = copy.copy(model_kwargs)
            candidate_kwargs = _prepare_attention_mask(
                candidate_kwargs, candidate_input_ids.shape[1], self.config.is_encoder_decoder
            )
            candidate_kwargs = _prepare_token_type_ids(candidate_kwargs, candidate_input_ids.shape[1])
            if (position_ids := candidate_kwargs.get("position_ids")) is not None and candidate_length > 0:
                new_length = candidate_length + position_ids.shape[-1]
                candidate_kwargs = _prepare_position_ids(candidate_kwargs, new_length, self.config.is_encoder_decoder)

            next_sequence_length = candidate_length + 1 if not is_first_iteration else None
            model_inputs = self.prepare_inputs_for_generation(
                candidate_input_ids,
                next_sequence_length=next_sequence_length,
                is_first_iteration=is_first_iteration,
                **candidate_kwargs,
            )

            if "logits_to_keep" in model_inputs:
                model_inputs["logits_to_keep"] = candidate_length + 1

            # We usually need to force returning hidden_states and some others if the candidate_generator requires the model's outputs
            if candidate_generator.requires_model_outputs:
                model_inputs |= candidate_generator.model_kwargs_overrides

            # 2.2. Run a forward pass on the candidate sequence
            outputs = self(**model_inputs)

            # 2.3. Process the new logits
            # .float() is needed to retain precision for later logits manipulations
            new_logits = outputs.logits[:, -candidate_length - 1 :].to(
                dtype=torch.float32, device=input_ids.device
            )  # excludes the input prompt if present
            next_token_logits = new_logits.clone()
            if len(logits_processor) > 0:
                for i in range(candidate_length + 1):
                    new_logits[:, i, :] = logits_processor(candidate_input_ids[:, : cur_len + i], new_logits[:, i, :])

            # 3. Select the accepted tokens. There are two possible cases:
            # Case 1: `do_sample=True` and we have logits for the candidates (originally from speculative decoding)
            # 👉 Apply algorithm 1 from the speculative decoding paper (https://huggingface.co/papers/2211.17192).
            if do_sample and candidate_logits is not None:
                valid_tokens, n_matches = _speculative_sampling(
                    candidate_input_ids,
                    candidate_logits,
                    candidate_length,
                    new_logits,
                    is_done_candidate,
                )

            # Case 2: all other cases (originally from assisted generation) 👉 Compare the tokens selected from the
            # original model logits with the candidate tokens. We can keep the candidate tokens until the first
            # mismatch, or until the max length is reached.
            else:
                if do_sample:
                    probs = new_logits.softmax(dim=-1)
                    selected_tokens = torch.multinomial(probs[0, :, :], num_samples=1).squeeze(1)[None, :]
                else:
                    selected_tokens = new_logits.argmax(dim=-1)

                candidate_new_tokens = candidate_input_ids[:, cur_len:]
                n_matches = ((~(candidate_new_tokens == selected_tokens[:, :-1])).cumsum(dim=-1) < 1).sum()

                # Ensure we don't generate beyond max_len or an EOS token
                if is_done_candidate and n_matches == candidate_length:
                    n_matches -= 1
                valid_tokens = selected_tokens[:, : n_matches + 1]

            # 4. Update variables according to the number of matching assistant tokens. Remember: the token generated
            # by the model after the last candidate match is also valid, as it is generated from a correct sequence.
            # Because of this last token, assisted generation search reduces to a normal greedy search/sample if there
            # is no match.

            # 4.1. Get the valid continuation, after the matching tokens
            input_ids = torch.cat((input_ids, valid_tokens), dim=-1)
            if streamer is not None:
                streamer.put(valid_tokens.cpu())
            new_cur_len = input_ids.shape[1]

            # 4.2. Discard past key values relative to unused assistant tokens
            outputs.past_key_values.crop(new_cur_len - 1)

            # 5. Update the candidate generation strategy if needed
            candidate_generator.update_candidate_strategy(input_ids, new_logits, n_matches)

            # synced_gpus: don't waste resources running the code we don't need; kwargs must be updated before skipping
            model_kwargs = self._update_model_kwargs_for_generation(
                outputs,
                model_kwargs,
                is_encoder_decoder=self.config.is_encoder_decoder,
                num_new_tokens=n_matches + 1,
            )
            if synced_gpus and this_peer_finished:
                continue

            # Store scores, attentions and hidden_states when required
            # Assistant: modified to append one tuple element per token, as in the other generation methods.
            if return_dict_in_generate:
                newly_added_length = n_matches + 1
                if output_scores:
                    scores += tuple(new_logits[:, i, :] for i in range(newly_added_length))
                if output_logits:
                    raw_logits += tuple(next_token_logits[:, i, :] for i in range(newly_added_length))

                newly_added_length = new_cur_len if is_first_iteration else newly_added_length
                if output_attentions:
                    if self.config.is_encoder_decoder:
                        cross_attentions = _split_model_outputs(
                            cross_attentions, outputs.cross_attentions, cur_len, newly_added_length
                        )
                        decoder_attentions = _split_model_outputs(
                            decoder_attentions,
                            outputs.decoder_attentions,
                            cur_len,
                            newly_added_length,
                            is_decoder_attention=True,
                        )
                    # some (V)LLMs have hard requirement on SDPA and thus never return attn
                    elif outputs.attentions[0] is not None:
                        decoder_attentions = _split_model_outputs(
                            decoder_attentions,
                            outputs.attentions,
                            cur_len,
                            newly_added_length,
                            is_decoder_attention=True,
                        )
                if output_hidden_states:
                    if self.config.is_encoder_decoder:
                        decoder_hidden_states = _split_model_outputs(
                            decoder_hidden_states, outputs.decoder_hidden_states, cur_len, newly_added_length
                        )
                    else:
                        decoder_hidden_states = _split_model_outputs(
                            decoder_hidden_states, outputs.hidden_states, cur_len, newly_added_length
                        )

            unfinished_sequences = unfinished_sequences & ~stopping_criteria(input_ids, scores)
            this_peer_finished = unfinished_sequences.max() == 0
            is_first_iteration = False

        if streamer is not None:
            streamer.end()

        if (
            isinstance(candidate_generator, AssistedCandidateGenerator)
            and candidate_generator.assistant_model.generation_config.num_assistant_tokens_schedule == "heuristic"
        ):
            candidate_generator.assistant_model.generation_config.num_assistant_tokens = (
                candidate_generator.num_assistant_tokens
            )
        if return_dict_in_generate:
            cache = None
            if any(cache_key in model_kwargs for cache_key in ALL_CACHE_NAMES):
                cache_key = next(cache_key for cache_key in ALL_CACHE_NAMES if cache_key in model_kwargs)
                cache = model_kwargs[cache_key]
            if self.config.is_encoder_decoder:
                return GenerateEncoderDecoderOutput(
                    sequences=input_ids,
                    scores=scores,
                    logits=raw_logits,
                    encoder_attentions=encoder_attentions,
                    encoder_hidden_states=encoder_hidden_states,
                    decoder_attentions=decoder_attentions,
                    cross_attentions=cross_attentions,
                    decoder_hidden_states=decoder_hidden_states,
                    past_key_values=cache,
                )
            else:
                return GenerateDecoderOnlyOutput(
                    sequences=input_ids,
                    scores=scores,
                    logits=raw_logits,
                    attentions=decoder_attentions,
                    hidden_states=decoder_hidden_states,
                    past_key_values=cache,
                )
        else:
            return input_ids

    # TODO: v5.1: make public once API stabilized
    def _prefill(
        self: "GenerativePreTrainedModel",
        input_ids: torch.LongTensor,
        generation_config: GenerationConfig,
        model_kwargs: dict,
        is_first_iteration: bool = True,
    ):
        """
        Perform the prefill stage of generation.

        Note that usually, the prefill stage is always the first iteration of a new input batch, and thus multimodal inputs etc
        should be treated as if it's the first iteration. However, for assisted decoding, assistants call `generate`
        several time in a row for a same batch of inputs, so we need to pass `is_first_iteration` here for such cases.
        """
        # When restarting from previous cache, the `input_ids` are either the FULL sequence, including previous inputs,
        # or only the new tokens but in this case the attention_mask still contains the FULL sequence (because otherwise we may
        # lose some early padding tokens information). So slice inputs according to that if needed
        # When restarting from `inputs_embeds`, it's always the FULL sequence, and we always need to slice
        next_sequence_length = None
        inputs_embeds = model_kwargs.get("inputs_embeds")
        use_inputs_embeds = False
        if not self.config.is_encoder_decoder and inputs_embeds is not None and is_first_iteration:
            use_inputs_embeds = True
        if (cache := model_kwargs.get("past_key_values")) is not None:
            past_length = cache.get_seq_length()
            # It will be sliced as inputs_embeds = inputs_embeds[:, -next_sequence_length:, :] in `prepare_inputs_for_generation`
            if use_inputs_embeds:
                next_sequence_length = model_kwargs["inputs_embeds"].shape[1] - past_length
            else:
                attention_mask_key = "decoder_attention_mask" if self.config.is_encoder_decoder else "attention_mask"
                attention_mask = model_kwargs.get(attention_mask_key)
                # In this case we need to slice - if it's smaller than the mask, only the new inputs were passed -> no need to do anything
                if attention_mask is not None and input_ids.shape[1] == attention_mask.shape[1]:
                    # inputs will be sliced as `input_ids[:, -next_sequence_length :]` in `prepare_inputs_for_generation`
                    next_sequence_length = input_ids.shape[1] - past_length

        # Usual prefill
        if generation_config.prefill_chunk_size is None:
            model_inputs = self.prepare_inputs_for_generation(
                input_ids,
                next_sequence_length=next_sequence_length,
                is_first_iteration=is_first_iteration,
                **model_kwargs,
            )
            return self(**model_inputs, return_dict=True)

        # Chunked prefill (for very large contexts)
        else:
            # Even if we are not compiling the forward, flex is always compiled when used. With chunked prefill, we may
            # end up needing just a bit more graphs than the default (which is 8). Doing this avoids very cryptic warnings
            getattr(torch, "_dynamo").config.cache_size_limit = 64

            chunk_size = generation_config.prefill_chunk_size
            input_chunks = torch.split(input_ids, chunk_size, dim=-1)

            if "past_key_values" not in model_kwargs:
                raise ValueError("Cannot use prefill chunking without a cache")

            model_forward = (
                self.get_compiled_call(generation_config.compile_config)
                if self._valid_auto_compile_criteria(model_kwargs, generation_config)
                else self.__call__
            )

            attention_mask = model_kwargs.pop("attention_mask", None)
            position_ids = model_kwargs.pop("position_ids", None)
            past_length = 0
            for input_chunk in input_chunks:
                current_length = past_length + input_chunk.shape[-1]
                if attention_mask is not None:
                    model_kwargs["attention_mask"] = attention_mask[:, :current_length]
                if position_ids is not None:
                    model_kwargs["position_ids"] = position_ids[:, past_length:current_length]
                model_inputs = self.prepare_inputs_for_generation(input_chunk, **model_kwargs)

                outputs = model_forward(**model_inputs, return_dict=True)

                model_kwargs["past_key_values"] = outputs.past_key_values
                past_length = current_length

            # Recreate the kwargs based on the full length
            model_kwargs["attention_mask"] = attention_mask
            model_kwargs["position_ids"] = position_ids

            # Latest outputs contain next token logits
            return outputs


def _speculative_sampling(
    candidate_input_ids,
    candidate_logits,
    candidate_length,
    new_logits,
    is_done_candidate,
):
    """
    Applies sampling as in the speculative decoding paper (https://huggingface.co/papers/2211.17192, algorithm 1). Returns
    the selected tokens, as well as the number of candidate matches.

    NOTE: Unless otherwise stated, the variable names match those in the paper.
    """
    new_candidate_input_ids = candidate_input_ids[:, -candidate_length:]
    # Gets the probabilities from the logits. q_i and p_i denote the assistant and model probabilities of the tokens
    # selected by the assistant, respectively.
    q = candidate_logits.softmax(dim=-1)
    q_i = q[:, torch.arange(candidate_length), new_candidate_input_ids].squeeze(0, 1)
    p = new_logits.softmax(dim=-1)
    p_i = p[:, torch.arange(candidate_length), new_candidate_input_ids].squeeze(0, 1)
    probability_ratio = p_i / q_i

    # When probability_ratio > 1 (i.e. q_i(x) < p_i(x), or "assistant probability of the candidate token is smaller
    # than the model probability for the same token"), keep the token. Otherwise reject with p = 1 - probability_ratio
    # (= keep with p = probability_ratio). Keep all the tokens until the first rejection
    r_i = torch.rand_like(probability_ratio)
    is_accepted = r_i <= probability_ratio
    n_matches = ((~is_accepted).cumsum(dim=-1) < 1).sum()  # this is `n` in algorithm 1

    # Ensure we don't generate beyond max_len or an EOS token (not in algorithm 1, but needed for correct behavior)
    if is_done_candidate and n_matches == candidate_length:
        # Output length is assumed to be `n_matches + 1`. Since we won't generate another token with the target model
        # due to acceptance on EOS we fix `n_matches`
        n_matches -= 1
        valid_tokens = new_candidate_input_ids[:, : n_matches + 1]
    else:
        # Next token selection: if there is a rejection, adjust the distribution from the main model before sampling.
        gamma = candidate_logits.shape[1]
        p_n_plus_1 = p[:, n_matches, :]
        if n_matches < gamma:
            q_n_plus_1 = q[:, n_matches, :]
            p_prime = torch.clamp((p_n_plus_1 - q_n_plus_1), min=0)
            p_prime.div_(p_prime.sum())
        else:
            p_prime = p_n_plus_1
        t = torch.multinomial(p_prime, num_samples=1).squeeze(1)[None, :]

        # The selected tokens include the matches (if any) plus the next sampled tokens
        if n_matches > 0:
            valid_tokens = torch.cat((new_candidate_input_ids[:, :n_matches], t), dim=-1)
        else:
            valid_tokens = t

    return valid_tokens, n_matches


def _split_model_outputs(outputs, new_outputs, cur_len, added_len, is_decoder_attention=False):
    """
    Given the (decoder/cross attentions)/(decoder hidden states) for multiple generated tokens, splits it into a tuple
    where each member corresponds to a single generated token.
    """
    # Retrocompatibility: in our generation functions, the first iteration includes the attention/hidden states for the
    # prompt.
    if len(outputs) == 0:
        new_tuple = ()
        for layer in new_outputs:
            last_dim_size = cur_len if is_decoder_attention else layer.shape[-1]
            new_tuple += (layer[..., :cur_len, :last_dim_size],)
        outputs += (new_tuple,)
        # The first iteration contains the prompt + 1 generated token, let's update the length variables accordingly
        cur_len += 1
        added_len -= cur_len

    for i in range(added_len):
        new_tuple = ()
        for layer in new_outputs:
            last_dim_size = cur_len + i if is_decoder_attention else layer.shape[-1]
            new_tuple += (layer[..., i : i + 1, :last_dim_size],)
        outputs += (new_tuple,)
    return outputs
