modeling.py

# Copyright 2022 The HuggingFace Team. 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 contextlib
import gc
import importlib
import inspect
import json
import logging
import os
import re
import shutil
import tempfile
import warnings
from collections import OrderedDict, defaultdict
from typing import Dict, List, Optional, Tuple, Union

import packaging
import torch
import torch.nn as nn

from ..state import AcceleratorState
from .constants import SAFE_WEIGHTS_NAME, WEIGHTS_NAME
from .dataclasses import AutocastKwargs, CustomDtype, DistributedType
from .imports import (
    is_mlu_available,
    is_mps_available,
    is_npu_available,
    is_peft_available,
    is_torch_xla_available,
    is_xpu_available,
)
from .offload import load_offloaded_weight, offload_weight, save_offload_index
from .tqdm import is_tqdm_available, tqdm
from .versions import compare_versions


if is_npu_available(check_device=False):
    import torch_npu  # noqa: F401

if is_mlu_available(check_device=False):
    import torch_mlu  # noqa: F401

from safetensors import safe_open
from safetensors.torch import load_file as safe_load_file


WEIGHTS_INDEX_NAME = "pytorch_model.bin.index.json"

logger = logging.getLogger(__name__)


def is_peft_model(model):
    from .other import extract_model_from_parallel

    if is_peft_available():
        from peft import PeftModel

    return is_peft_available() and isinstance(extract_model_from_parallel(model), PeftModel)


def check_device_same(first_device, second_device):
    """
    Utility method to check if two `torch` devices are similar. When dealing with CUDA devices, torch throws `False`
    for `torch.device("cuda") == torch.device("cuda:0")` whereas they should be the same

    Args:
        first_device (`torch.device`):
            First device to check
        second_device (`torch.device`):
            Second device to check
    """
    if first_device.type != second_device.type:
        return False

    if first_device.type == "cuda" and first_device.index is None:
        # In case the first_device is a cuda device and have
        # the index attribute set to `None`, default it to `0`
        first_device = torch.device("cuda", index=0)

    if second_device.type == "cuda" and second_device.index is None:
        # In case the second_device is a cuda device and have
        # the index attribute set to `None`, default it to `0`
        second_device = torch.device("cuda", index=0)

    return first_device == second_device


def convert_file_size_to_int(size: Union[int, str]):
    """
    Converts a size expressed as a string with digits an unit (like `"5MB"`) to an integer (in bytes).

    Args:
        size (`int` or `str`): The size to convert. Will be directly returned if an `int`.

    Example:

    ```py
    >>> convert_file_size_to_int("1MiB")
    1048576
    ```
    """
    mem_size = -1
    err_msg = (
        f"`size` {size} is not in a valid format. Use an integer for bytes, or a string with an unit (like '5.0GB')."
    )
    try:
        if isinstance(size, int):
            mem_size = size
        elif size.upper().endswith("GIB"):
            mem_size = int(float(size[:-3]) * (2**30))
        elif size.upper().endswith("MIB"):
            mem_size = int(float(size[:-3]) * (2**20))
        elif size.upper().endswith("KIB"):
            mem_size = int(float(size[:-3]) * (2**10))
        elif size.upper().endswith("GB"):
            int_size = int(float(size[:-2]) * (10**9))
            mem_size = int_size // 8 if size.endswith("b") else int_size
        elif size.upper().endswith("MB"):
            int_size = int(float(size[:-2]) * (10**6))
            mem_size = int_size // 8 if size.endswith("b") else int_size
        elif size.upper().endswith("KB"):
            int_size = int(float(size[:-2]) * (10**3))
            mem_size = int_size // 8 if size.endswith("b") else int_size
    except ValueError:
        raise ValueError(err_msg)

    if mem_size < 0:
        raise ValueError(err_msg)
    return mem_size


def dtype_byte_size(dtype: torch.dtype):
    """
    Returns the size (in bytes) occupied by one parameter of type `dtype`.

    Example:

    ```py
    >>> dtype_byte_size(torch.float32)
    4
    ```
    """
    if dtype == torch.bool:
        return 1 / 8
    elif dtype == CustomDtype.INT2:
        return 1 / 4
    elif dtype == CustomDtype.INT4:
        return 1 / 2
    elif dtype == CustomDtype.FP8:
        return 1
    bit_search = re.search(r"[^\d](\d+)$", str(dtype))
    if bit_search is None:
        raise ValueError(f"`dtype` is not a valid dtype: {dtype}.")
    bit_size = int(bit_search.groups()[0])
    return bit_size // 8


def id_tensor_storage(tensor: torch.Tensor) -> Tuple[torch.device, int, int]:
    """
    Unique identifier to a tensor storage. Multiple different tensors can share the same underlying storage. For
    example, "meta" tensors all share the same storage, and thus their identifier will all be equal. This identifier is
    guaranteed to be unique and constant for this tensor's storage during its lifetime. Two tensor storages with
    non-overlapping lifetimes may have the same id.
    """
    _SIZE = {
        torch.int64: 8,
        torch.float32: 4,
        torch.int32: 4,
        torch.bfloat16: 2,
        torch.float16: 2,
        torch.int16: 2,
        torch.uint8: 1,
        torch.int8: 1,
        torch.bool: 1,
        torch.float64: 8,
    }
    try:
        storage_ptr = tensor.untyped_storage().data_ptr()
        storage_size = tensor.untyped_storage().nbytes()
    except Exception:
        # Fallback for torch==1.10
        try:
            storage_ptr = tensor.storage().data_ptr()
            storage_size = tensor.storage().size() * _SIZE[tensor.dtype]
        except NotImplementedError:
            # Fallback for meta storage
            storage_ptr = 0
            # On torch >=2.0 this is the tensor size
            storage_size = tensor.nelement() * _SIZE[tensor.dtype]

    return tensor.device, storage_ptr, storage_size


def shard_checkpoint(
    state_dict: Dict[str, torch.Tensor], max_shard_size: Union[int, str] = "10GB", weights_name: str = WEIGHTS_NAME
):
    """
    Splits a model state dictionary in sub-checkpoints so that the final size of each sub-checkpoint does not exceed a
    given size.

    The sub-checkpoints are determined by iterating through the `state_dict` in the order of its keys, so there is no
    optimization made to make each sub-checkpoint as close as possible to the maximum size passed. For example, if the
    limit is 10GB and we have weights of sizes [6GB, 6GB, 2GB, 6GB, 2GB, 2GB] they will get sharded as [6GB], [6+2GB],
    [6+2+2GB] and not [6+2+2GB], [6+2GB], [6GB].

    <Tip warning={true}>

    If one of the model's weight is bigger that `max_sahrd_size`, it will end up in its own sub-checkpoint which will
    have a size greater than `max_shard_size`.

    </Tip>

    Args:
        state_dict (`Dict[str, torch.Tensor]`): The state dictionary of a model to save.
        max_shard_size (`int` or `str`, *optional*, defaults to `"10GB"`):
            The maximum size of each sub-checkpoint. If expressed as a string, needs to be digits followed by a unit
            (like `"5MB"`).
        weights_name (`str`, *optional*, defaults to `"pytorch_model.bin"`):
            The name of the model save file.
    """
    max_shard_size = convert_file_size_to_int(max_shard_size)

    sharded_state_dicts = [{}]
    last_block_size = 0
    total_size = 0
    storage_id_to_block = {}

    for key, weight in state_dict.items():
        # when bnb serialization is used the weights in the state dict can be strings
        # check: https://github.com/huggingface/transformers/pull/24416 for more details
        if isinstance(weight, str):
            continue
        else:
            storage_id = id_tensor_storage(weight)

        # If a `weight` shares the same underlying storage as another tensor, we put `weight` in the same `block`
        if storage_id in storage_id_to_block:
            block_id = storage_id_to_block[storage_id]
            sharded_state_dicts[block_id][key] = weight
            continue

        weight_size = weight.numel() * dtype_byte_size(weight.dtype)

        # If this weight is going to tip up over the maximal size, we split.
        if last_block_size + weight_size > max_shard_size:
            sharded_state_dicts.append({})
            last_block_size = 0

        sharded_state_dicts[-1][key] = weight
        last_block_size += weight_size
        total_size += weight_size
        storage_id_to_block[storage_id] = len(sharded_state_dicts) - 1

    # If we only have one shard, we return it
    if len(sharded_state_dicts) == 1:
        return {weights_name: sharded_state_dicts[0]}, None

    # Otherwise, let's build the index
    weight_map = {}
    shards = {}
    for idx, shard in enumerate(sharded_state_dicts):
        shard_file = weights_name.replace(".bin", f"-{idx + 1:05d}-of-{len(sharded_state_dicts):05d}.bin")
        shard_file = shard_file.replace(
            ".safetensors", f"-{idx + 1:05d}-of-{len(sharded_state_dicts):05d}.safetensors"
        )
        shards[shard_file] = shard
        for key in shard.keys():
            weight_map[key] = shard_file

    # Add the metadata
    metadata = {"total_size": total_size}
    index = {"metadata": metadata, "weight_map": weight_map}
    return shards, index


def set_module_tensor_to_device(
    module: nn.Module,
    tensor_name: str,
    device: Union[int, str, torch.device],
    value: Optional[torch.Tensor] = None,
    dtype: Optional[Union[str, torch.dtype]] = None,
    fp16_statistics: Optional[torch.HalfTensor] = None,
    tied_params_map: Optional[Dict[int, Dict[torch.device, torch.Tensor]]] = None,
):
    """
    A helper function to set a given tensor (parameter of buffer) of a module on a specific device (note that doing
    `param.to(device)` creates a new tensor not linked to the parameter, which is why we need this function).

    Args:
        module (`torch.nn.Module`):
            The module in which the tensor we want to move lives.
        tensor_name (`str`):
            The full name of the parameter/buffer.
        device (`int`, `str` or `torch.device`):
            The device on which to set the tensor.
        value (`torch.Tensor`, *optional*):
            The value of the tensor (useful when going from the meta device to any other device).
        dtype (`torch.dtype`, *optional*):
            If passed along the value of the parameter will be cast to this `dtype`. Otherwise, `value` will be cast to
            the dtype of the existing parameter in the model.
        fp16_statistics (`torch.HalfTensor`, *optional*):
            The list of fp16 statistics to set on the module, used for 8 bit model serialization.
        tied_params_map (Dict[int, Dict[torch.device, torch.Tensor]], *optional*, defaults to `None`):
            A map of current data pointers to dictionaries of devices to already dispatched tied weights. For a given
            execution device, this parameter is useful to reuse the first available pointer of a shared weight on the
            device for all others, instead of duplicating memory.
    """
    # Recurse if needed
    if "." in tensor_name:
        splits = tensor_name.split(".")
        for split in splits[:-1]:
            new_module = getattr(module, split)
            if new_module is None:
                raise ValueError(f"{module} has no attribute {split}.")
            module = new_module
        tensor_name = splits[-1]

    if tensor_name not in module._parameters and tensor_name not in module._buffers:
        raise ValueError(f"{module} does not have a parameter or a buffer named {tensor_name}.")
    is_buffer = tensor_name in module._buffers
    old_value = getattr(module, tensor_name)

    # Treat the case where old_value (or a custom `value`, typically offloaded to RAM/disk) belongs to a tied group, and one of the weight
    # in the tied group has already been dispatched to the device, by avoiding reallocating memory on the device and just copying the pointer.
    if (
        value is not None
        and tied_params_map is not None
        and value.data_ptr() in tied_params_map
        and device in tied_params_map[value.data_ptr()]
    ):
        module._parameters[tensor_name] = tied_params_map[value.data_ptr()][device]
        return
    elif (
        tied_params_map is not None
        and old_value.data_ptr() in tied_params_map
        and device in tied_params_map[old_value.data_ptr()]
    ):
        module._parameters[tensor_name] = tied_params_map[old_value.data_ptr()][device]
        return

    if old_value.device == torch.device("meta") and device not in ["meta", torch.device("meta")] and value is None:
        raise ValueError(f"{tensor_name} is on the meta device, we need a `value` to put in on {device}.")

    if value is not None:
        if old_value.shape != value.shape:
            raise ValueError(
                f'Trying to set a tensor of shape {value.shape} in "{tensor_name}" (which has shape {old_value.shape}), this look incorrect.'
            )

        if dtype is None:
            # For compatibility with PyTorch load_state_dict which converts state dict dtype to existing dtype in model
            value = value.to(old_value.dtype)
        elif not str(value.dtype).startswith(("torch.uint", "torch.int", "torch.bool")):
            value = value.to(dtype)

    param = module._parameters[tensor_name] if tensor_name in module._parameters else None
    param_cls = type(param)

    device_quantization = None
    with torch.no_grad():
        # leave it on cpu first before moving them to cuda
        # # fix the case where the device is meta, we don't want to put it on cpu because there is no data =0
        if (
            param is not None
            and param.device.type != "cuda"
            and torch.device(device).type == "cuda"
            and param_cls.__name__ in ["Int8Params", "FP4Params", "Params4bit"]
        ):
            device_quantization = device
            device = "cpu"
        # `torch.Tensor.to(<int num>)` is not supported by `torch_npu` (see this [issue](https://github.com/Ascend/pytorch/issues/16)).
        if is_npu_available() and isinstance(device, int):
            device = f"npu:{device}"
        elif is_mlu_available() and isinstance(device, int):
            device = f"mlu:{device}"
        if is_xpu_available() and isinstance(device, int):
            device = f"xpu:{device}"
        if value is None:
            new_value = old_value.to(device)
            if dtype is not None and device in ["meta", torch.device("meta")]:
                if not str(old_value.dtype).startswith(("torch.uint", "torch.int", "torch.bool")):
                    new_value = new_value.to(dtype)

                if not is_buffer:
                    module._parameters[tensor_name] = param_cls(new_value, requires_grad=old_value.requires_grad)
        elif isinstance(value, torch.Tensor):
            new_value = value.to(device)
        else:
            new_value = torch.tensor(value, device=device)
        if device_quantization is not None:
            device = device_quantization
        if is_buffer:
            module._buffers[tensor_name] = new_value
        elif value is not None or not check_device_same(torch.device(device), module._parameters[tensor_name].device):
            param_cls = type(module._parameters[tensor_name])
            kwargs = module._parameters[tensor_name].__dict__
            if param_cls.__name__ in ["Int8Params", "FP4Params"]:
                if param_cls.__name__ == "Int8Params" and new_value.dtype == torch.float32:
                    # downcast to fp16 if any - needed for 8bit serialization
                    new_value = new_value.to(torch.float16)
                # quantize module that are going to stay on the cpu so that we offload quantized weights
                if device == "cpu" and param_cls.__name__ == "Int8Params":
                    new_value = param_cls(new_value, requires_grad=old_value.requires_grad, **kwargs).to(0).to("cpu")
                    new_value.CB = new_value.CB.to("cpu")
                    new_value.SCB = new_value.SCB.to("cpu")
                else:
                    new_value = param_cls(new_value, requires_grad=old_value.requires_grad, **kwargs).to(device)
            elif param_cls.__name__ in ["QTensor", "QBitsTensor"]:
                new_value = torch.nn.Parameter(new_value, requires_grad=old_value.requires_grad).to(device)
            else:
                new_value = param_cls(new_value, requires_grad=old_value.requires_grad).to(device)

            module._parameters[tensor_name] = new_value
            if fp16_statistics is not None:
                module._parameters[tensor_name].SCB = fp16_statistics.to(device)
                del fp16_statistics
            # as we put the weight to meta, it doesn't have SCB attr anymore. make sure that it is not a meta weight
            if (
                module.__class__.__name__ == "Linear8bitLt"
                and getattr(module.weight, "SCB", None) is None
                and str(module.weight.device) != "meta"
            ):
                # quantize only if necessary
                device_index = torch.device(device).index if torch.device(device).type == "cuda" else None
                if not getattr(module.weight, "SCB", None) and device_index is not None:
                    if module.bias is not None and module.bias.device.type != "meta":
                        # if a bias exists, we need to wait until the bias is set on the correct device
                        module = module.cuda(device_index)
                    elif module.bias is None:
                        # if no bias exists, we can quantize right away
                        module = module.cuda(device_index)
            elif module.__class__.__name__ == "Linear4bit" and getattr(module.weight, "quant_state", None) is None:
                # quantize only if necessary
                device_index = torch.device(device).index if torch.device(device).type == "cuda" else None
                if not getattr(module.weight, "quant_state", None) and device_index is not None:
                    module.weight = module.weight.cuda(device_index)
    # clean pre and post foward hook
    if is_npu_available():
        torch.npu.empty_cache()
    elif is_mlu_available():
        torch.mlu.empty_cache()
    elif is_xpu_available():
        torch.xpu.empty_cache()
    else:
        torch.cuda.empty_cache()

    # When handling tied weights, we update tied_params_map to keep track of the tied weights that have already been allocated on the device in
    # order to avoid duplicating memory, see above.
    if (
        tied_params_map is not None
        and old_value.data_ptr() in tied_params_map
        and device not in tied_params_map[old_value.data_ptr()]
    ):
        tied_params_map[old_value.data_ptr()][device] = new_value
    elif (
        value is not None
        and tied_params_map is not None
        and value.data_ptr() in tied_params_map
        and device not in tied_params_map[value.data_ptr()]
    ):
        tied_params_map[value.data_ptr()][device] = new_value


def named_module_tensors(
    module: nn.Module, include_buffers: bool = True, recurse: bool = False, remove_non_persistent: bool = False
):
    """
    A helper function that gathers all the tensors (parameters + buffers) of a given module. If `include_buffers=True`
    it's the same as doing `module.named_parameters(recurse=recurse) + module.named_buffers(recurse=recurse)`.

    Args:
        module (`torch.nn.Module`):
            The module we want the tensors on.
        include_buffer (`bool`, *optional*, defaults to `True`):
            Whether or not to include the buffers in the result.
        recurse (`bool`, *optional`, defaults to `False`):
            Whether or not to go look in every submodule or just return the direct parameters and buffers.
        remove_non_persistent (`bool`, *optional*, defaults to `False`):
            Whether or not to remove the non persistent buffer from the buffers. Useful only when include_buffers =
            True
    """
    yield from module.named_parameters(recurse=recurse)

    if include_buffers:
        non_persistent_buffers = set()
        if remove_non_persistent:
            non_persistent_buffers = get_non_persistent_buffers(module, recurse=recurse)
        for named_buffer in module.named_buffers(recurse=recurse):
            name, _ = named_buffer
            if name not in non_persistent_buffers:
                yield named_buffer


def get_non_persistent_buffers(module: nn.Module, recurse: bool = False):
    """
    Gather all non persistent buffers of a given modules into a set

    Args:
        module (`nn.Module`):
            The module we want the non persistent buffers on.
        recurse (`bool`, *optional*, defaults to `False`):
            Whether or not to go look in every submodule or just return the direct non persistent buffers.
    """

    non_persistent_buffers_set = module._non_persistent_buffers_set
    if recurse:
        for _, m in module.named_modules():
            non_persistent_buffers_set |= m._non_persistent_buffers_set

    return non_persistent_buffers_set


class FindTiedParametersResult(list):
    """
    This is a subclass of a list to handle backward compatibility for Transformers. Do not rely on the fact this is not
    a list or on the `values` method as in the future this will be removed.
    """

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    def values(self):
        # TODO: at the next Transformers release (4.28.0) issue a deprecation warning here.
        return sum([x[1:] for x in self], [])


def check_tied_parameters_in_config(model: nn.Module):
    """
    Check if there is any indication in the given model that some weights should be tied.

    Args:
        model (`torch.nn.Module`): The model to inspect

    Returns:
        bool: True if the model needs to have tied weights
    """

    # based on model.tie_weights() method
    has_tied_word_embedding = False
    has_tied_encoder_decoder = False
    has_tied_module = False

    if "PreTrainedModel" in [c.__name__ for c in inspect.getmro(model.__class__)]:
        has_tied_word_embedding = (
            hasattr(model, "config")
            and getattr(model.config, "tie_word_embeddings", False)
            and model.get_output_embeddings()
        )
        has_tied_encoder_decoder = (
            hasattr(model, "config")
            and getattr(model.config, "is_encoder_decoder", False)
            and getattr(model.config, "tie_encoder_decoder", False)
        )
        has_tied_module = any(hasattr(module, "_tie_weights") for module in model.modules())

    return any([has_tied_word_embedding, has_tied_encoder_decoder, has_tied_module])


def _get_param_device(param, device_map):
    if param in device_map:
        return device_map[param]
    parent_param = ".".join(param.split(".")[:-1])
    if parent_param == param:
        raise ValueError(f"The `device_map` does not contain the module {param}.")
    else:
        return _get_param_device(parent_param, device_map)


def check_tied_parameters_on_same_device(tied_params, device_map):
    """
    Check if tied parameters are on the same device

    Args:
        tied_params (`List[List[str]]`):
            A list of lists of parameter names being all tied together.

        device_map (`Dict[str, Union[int, str, torch.device]]`):
            A map that specifies where each submodule should go.

    """
    for tie_param in tied_params:
        tie_param_devices = {}
        for param in tie_param:
            tie_param_devices[param] = _get_param_device(param, device_map)
        if len(set(tie_param_devices.values())) > 1:
            logger.warn(
                f"Tied parameters are on different devices: {tie_param_devices}. "
                "Please modify your custom device map or set `device_map='auto'`. "
            )


def find_tied_parameters(model: nn.Module, **kwargs):
    """
    Find the tied parameters in a given model.

    <Tip warning={true}>

    The signature accepts keyword arguments, but they are for the recursive part of this function and you should ignore
    them.

    </Tip>

    Args:
        model (`torch.nn.Module`): The model to inspect.

    Returns:
        List[List[str]]: A list of lists of parameter names being all tied together.

    Example:

    ```py
    >>> from collections import OrderedDict
    >>> import torch.nn as nn

    >>> model = nn.Sequential(OrderedDict([("linear1", nn.Linear(4, 4)), ("linear2", nn.Linear(4, 4))]))
    >>> model.linear2.weight = model.linear1.weight
    >>> find_tied_parameters(model)
    [['linear1.weight', 'linear2.weight']]
    ```
    """
    # Initialize result and named_parameters before recursing.
    named_parameters = kwargs.get("named_parameters", None)
    prefix = kwargs.get("prefix", "")
    result = kwargs.get("result", {})

    if named_parameters is None:
        named_parameters = {n: p for n, p in model.named_parameters()}
    else:
        # A tied parameter will not be in the full `named_parameters` seen above but will be in the `named_parameters`
        # of the submodule it belongs to. So while recursing we track the names that are not in the initial
        # `named_parameters`.
        for name, parameter in model.named_parameters():
            full_name = name if prefix == "" else f"{prefix}.{name}"
            if full_name not in named_parameters:
                # When we find one, it has to be one of the existing parameters.
                for new_name, new_param in named_parameters.items():
                    if new_param is parameter:
                        if new_name not in result:
                            result[new_name] = []
                        result[new_name].append(full_name)

    # Once we have treated direct parameters, we move to the child modules.
    for name, child in model.named_children():
        child_name = name if prefix == "" else f"{prefix}.{name}"
        find_tied_parameters(child, named_parameters=named_parameters, prefix=child_name, result=result)

    return FindTiedParametersResult([sorted([weight] + list(set(tied))) for weight, tied in result.items()])


def retie_parameters(model, tied_params):
    """
    Reties tied parameters in a given model if the link was broken (for instance when adding hooks).

    Args:
        model (`torch.nn.Module`):
            The model in which to retie parameters.
        tied_params (`List[List[str]]`):
            A mapping parameter name to tied parameter name as obtained by `find_tied_parameters`.
    """
    for tied_group in tied_params:
        param_to_tie = None
        # two loops : the first one to set param_to_tie , the second one to change the values of tied_group
        for param_name in tied_group:
            module = model
            splits = param_name.split(".")
            for split in splits[:-1]:
                module = getattr(module, split)
            param = getattr(module, splits[-1])
            if param_to_tie is None and param.device != torch.device("meta"):
                param_to_tie = param
                break
        if param_to_tie is not None:
            for param_name in tied_group:
                module = model
                splits = param_name.split(".")
                for split in splits[:-1]:
                    module = getattr(module, split)
                setattr(module, splits[-1], param_to_tie)


def _get_proper_dtype(dtype: Union[str, torch.device]) -> torch.dtype:
    """
    Just does torch.dtype(dtype) if necessary.
    """
    if isinstance(dtype, str):
        # We accept "torch.float16" or just "float16"
        dtype = dtype.replace("torch.", "")
        dtype = getattr(torch, dtype)
    return dtype


def compute_module_sizes(
    model: nn.Module,
    dtype: Optional[Union[str, torch.device]] = None,
    special_dtypes: Optional[Dict[str, Union[str, torch.device]]] = None,
    buffers_only: bool = False,
):
    """
    Compute the size of each submodule of a given model.
    """
    if dtype is not None:
        dtype = _get_proper_dtype(dtype)
        dtype_size = dtype_byte_size(dtype)
    if special_dtypes is not None:
        special_dtypes = {key: _get_proper_dtype(dtyp) for key, dtyp in special_dtypes.items()}
        special_dtypes_size = {key: dtype_byte_size(dtyp) for key, dtyp in special_dtypes.items()}
    module_sizes = defaultdict(int)

    module_list = []

    if not buffers_only:
        module_list = named_module_tensors(model, recurse=True)
    else:
        module_list = model.named_buffers(recurse=True)

    for name, tensor in module_list:
        if special_dtypes is not None and name in special_dtypes:
            size = tensor.numel() * special_dtypes_size[name]
        elif dtype is None:
            size = tensor.numel() * dtype_byte_size(tensor.dtype)
        elif str(tensor.dtype).startswith(("torch.uint", "torch.int", "torch.bool")):
            # According to the code in set_module_tensor_to_device, these types won't be converted
            # so use their original size here
            size = tensor.numel() * dtype_byte_size(tensor.dtype)
        else:
            size = tensor.numel() * min(dtype_size, dtype_byte_size(tensor.dtype))
        name_parts = name.split(".")
        for idx in range(len(name_parts) + 1):
            module_sizes[".".join(name_parts[:idx])] += size

    return module_sizes


def compute_module_total_buffer_size(
    model: nn.Module,
    dtype: Optional[Union[str, torch.device]] = None,
    special_dtypes: Optional[Dict[str, Union[str, torch.device]]] = None,
):
    """
    Compute the total size of buffers in each submodule of a given model.
    """
    module_sizes = compute_module_sizes(model, dtype=dtype, special_dtypes=special_dtypes, buffers_only=True)
    return module_sizes.get("", 0)


def get_max_layer_size(
    modules: List[Tuple[str, torch.nn.Module]], module_sizes: Dict[str, int], no_split_module_classes: List[str]
):
    """
    Utility function that will scan a list of named modules and return the maximum size used by one full layer. The
    definition of a layer being:
    - a module with no direct children (just parameters and buffers)
    - a module whose class name is in the list `no_split_module_classes`

    Args:
        modules (`List[Tuple[str, torch.nn.Module]]`):
            The list of named modules where we want to determine the maximum layer size.
        module_sizes (`Dict[str, int]`):
            A dictionary mapping each layer name to its size (as generated by `compute_module_sizes`).
        no_split_module_classes (`List[str]`):
            A list of class names for layers we don't want to be split.

    Returns:
        `Tuple[int, List[str]]`: The maximum size of a layer with the list of layer names realizing that maximum size.
    """
    max_size = 0
    layer_names = []
    modules_to_treat = modules.copy()
    while len(modules_to_treat) > 0:
        module_name, module = modules_to_treat.pop(0)
        modules_children = list(module.named_children()) if isinstance(module, torch.nn.Module) else []
        if len(modules_children) == 0 or module.__class__.__name__ in no_split_module_classes:
            # No splitting this one so we compare to the max_size
            size = module_sizes[module_name]
            if size > max_size:
                max_size = size
                layer_names = [module_name]
            elif size == max_size:
                layer_names.append(module_name)
        else:
            modules_to_treat = [(f"{module_name}.{n}", v) for n, v in modules_children] + modules_to_treat
    return max_size, layer_names


def get_max_memory(max_memory: Optional[Dict[Union[int, str], Union[int, str]]] = None):
    """
    Get the maximum memory available if nothing is passed, converts string to int otherwise.
    """
    import psutil

    if max_memory is None:
        if not (torch.cuda.is_available() or is_npu_available() or is_mlu_available() or is_xpu_available()):
            max_memory = {}

        else:
            # Make sure CUDA is initialized on each GPU to have the right memory info.
            if is_npu_available():
                for i in range(torch.npu.device_count()):
                    _ = torch.tensor(0, device=torch.device("npu", i))
                max_memory = {i: torch.npu.mem_get_info(i)[0] for i in range(torch.npu.device_count())}
            elif is_mlu_available():
                for i in range(torch.mlu.device_count()):
                    _ = torch.tensor(0, device=torch.device("mlu", i))
                max_memory = {i: torch.mlu.mem_get_info(i)[0] for i in range(torch.mlu.device_count())}
            elif is_xpu_available():
                for i in range(torch.xpu.device_count()):
                    _ = torch.tensor(0, device=torch.device("xpu", i))
                max_memory = {i: torch.xpu.max_memory_allocated(i) for i in range(torch.xpu.device_count())}
            else:
                for i in range(torch.cuda.device_count()):
                    _ = torch.tensor([0], device=i)
                max_memory = {i: torch.cuda.mem_get_info(i)[0] for i in range(torch.cuda.device_count())}
        # allocate everything in the mps device as the RAM is shared
        if is_mps_available():
            max_memory["mps"] = psutil.virtual_memory().available
        else:
            max_memory["cpu"] = psutil.virtual_memory().available
        return max_memory

    for key in max_memory:
        if isinstance(max_memory[key], str):
            max_memory[key] = convert_file_size_to_int(max_memory[key])

    # Need to sort the device by type to make sure that we allocate the gpu first.
    # As gpu/npu/xpu are represented by int, we need to sort them first.
    gpu_devices = [k for k in max_memory.keys() if isinstance(k, int)]
    gpu_devices.sort()
    # check if gpu/npu/xpu devices are available and if not, throw a warning
    if is_npu_available():
        num_devices = torch.npu.device_count()
    elif is_mlu_available():
        num_devices = torch.mlu.device_count()
    elif is_xpu_available():
        num_devices = torch.xpu.device_count()
    else:
        num_devices = torch.cuda.device_count()
    for device in gpu_devices:
        if device >= num_devices or device < 0:
            logger.warning(f"Device {device} is not available, available devices are {list(range(num_devices))}")
    # Add the other devices in the preset order if they are available
    all_devices = gpu_devices + [k for k in ["mps", "cpu", "disk"] if k in max_memory.keys()]
    # Raise an error if a device is not recognized
    for k in max_memory.keys():
        if k not in all_devices:
            raise ValueError(
                f"Device {k} is not recognized, available devices are integers(for GPU/XPU), 'mps', 'cpu' and 'disk'"
            )
    max_memory = {k: max_memory[k] for k in all_devices}

    return max_memory


def clean_device_map(device_map: Dict[str, Union[int, str, torch.device]], module_name: str = ""):
    """
    Cleans a device_map by grouping all submodules that go on the same device together.
    """
    # Get the value of the current module and if there is only one split across several keys, regroup it.
    prefix = "" if module_name == "" else f"{module_name}."
    values = [v for k, v in device_map.items() if k.startswith(prefix)]
    if len(set(values)) == 1 and len(values) > 1:
        for k in [k for k in device_map if k.startswith(prefix)]:
            del device_map[k]
        device_map[module_name] = values[0]

    # Recurse over the children
    children_modules = [k for k in device_map.keys() if k.startswith(prefix) and len(k) > len(module_name)]
    idx = len(module_name.split(".")) + 1 if len(module_name) > 0 else 1
    children_modules = set(".".join(k.split(".")[:idx]) for k in children_modules)
    for child in children_modules:
        clean_device_map(device_map, module_name=child)

    return device_map


def load_offloaded_weights(model, index, offload_folder):
    """
    Loads the weights from the offload folder into the model.

    Args:
        model (`torch.nn.Module`):
            The model to load the weights into.
        index (`dict`):
            A dictionary containing the parameter name and its metadata for each parameter that was offloaded from the
            model.
        offload_folder (`str`):
            The folder where the offloaded weights are stored.
    """
    if index is None or len(index) == 0:
        # Nothing to do
        return
    for param_name, metadata in index.items():
        if "SCB" in param_name:
            continue
        fp16_statistics = None
        if "weight" in param_name and param_name.replace("weight", "SCB") in index.keys():
            weight_name = param_name.replace("weight", "SCB")
            fp16_statistics = load_offloaded_weight(
                os.path.join(offload_folder, f"{weight_name}.dat"), index[weight_name]
            )
        tensor_file = os.path.join(offload_folder, f"{param_name}.dat")
        weight = load_offloaded_weight(tensor_file, metadata)
        set_module_tensor_to_device(model, param_name, "cpu", value=weight, fp16_statistics=fp16_statistics)


def get_balanced_memory(
    model: nn.Module,
    max_memory: Optional[Dict[Union[int, str], Union[int, str]]] = None,
    no_split_module_classes: Optional[List[str]] = None,
    dtype: Optional[Union[str, torch.dtype]] = None,
    special_dtypes: Optional[Dict[str, Union[str, torch.device]]] = None,
    low_zero: bool = False,
):
    """
    Compute a `max_memory` dictionary for [`infer_auto_device_map`] that will balance the use of each available GPU.

    <Tip>

    All computation is done analyzing sizes and dtypes of the model parameters. As a result, the model can be on the
    meta device (as it would if initialized within the `init_empty_weights` context manager).

    </Tip>

    Args:
        model (`torch.nn.Module`):
            The model to analyze.
        max_memory (`Dict`, *optional*):
            A dictionary device identifier to maximum memory. Will default to the maximum memory available if unset.
            Example: `max_memory={0: "1GB"}`.
        no_split_module_classes (`List[str]`, *optional*):
            A list of layer class names that should never be split across device (for instance any layer that has a
            residual connection).
        dtype (`str` or `torch.dtype`, *optional*):
            If provided, the weights will be converted to that type when loaded.
        special_dtypes (`Dict[str, Union[str, torch.device]]`, *optional*):
            If provided, special dtypes to consider for some specific weights (will override dtype used as default for
            all weights).
        low_zero (`bool`, *optional*):
            Minimizes the number of weights on GPU 0, which is convenient when it's used for other operations (like the
            Transformers generate function).
    """
    # Get default / clean up max_memory
    user_not_set_max_memory = max_memory is None
    max_memory = get_max_memory(max_memory)

    if is_npu_available():
        num_devices = len([d for d in max_memory if torch.device(d).type == "npu" and max_memory[d] > 0])
    elif is_mlu_available():
        num_devices = len([d for d in max_memory if torch.device(d).type == "mlu" and max_memory[d] > 0])
    elif is_xpu_available():
        num_devices = len(
            [
                d
                for d in max_memory
                if (
                    d != "cpu"
                    and (torch.device(d).type == "xpu" or torch.xpu.get_device_properties(d).dev_type == "gpu")
                )
                and max_memory[d] > 0
            ]
        )
    else:
        num_devices = len([d for d in max_memory if torch.device(d).type == "cuda" and max_memory[d] > 0])

    if num_devices == 0:
        return max_memory

    if num_devices == 1:
        # We cannot do low_zero on just one GPU, but we will still reserve some memory for the buffer
        low_zero = False
        # If user just asked us to handle memory usage, we should avoid OOM
        if user_not_set_max_memory:
            for key in max_memory.keys():
                if isinstance(key, int):
                    max_memory[key] *= 0.9  # 90% is a good compromise
                    logger.info(
                        f"We will use 90% of the memory on device {key} for storing the model, and 10% for the buffer to avoid OOM. "
                        "You can set `max_memory` in to a higher value to use more memory (at your own risk)."
                    )
                    break  # only one device

    module_sizes = compute_module_sizes(model, dtype=dtype, special_dtypes=special_dtypes)
    per_gpu = module_sizes[""] // (num_devices - 1 if low_zero else num_devices)

    # We can't just set the memory to model_size // num_devices as it will end being too small: each GPU will get
    # slightly less layers and some layers will end up offload at the end. So this function computes a buffer size to
    # add which is the biggest of:
    # - the size of no split block (if applicable)
    # - the mean of the layer sizes
    if no_split_module_classes is None:
        no_split_module_classes = []
    elif not isinstance(no_split_module_classes, (list, tuple)):
        no_split_module_classes = [no_split_module_classes]

    # Identify the size of the no_split_block modules
    if len(no_split_module_classes) > 0:
        no_split_children = {}
        for name, size in module_sizes.items():
            if name == "":
                continue
            submodule = model
            for submodule_name in name.split("."):
                submodule = getattr(submodule, submodule_name)
            class_name = submodule.__class__.__name__
            if class_name in no_split_module_classes and class_name not in no_split_children:
                no_split_children[class_name] = size

            if set(no_split_children.keys()) == set(no_split_module_classes):
                break
        buffer = max(no_split_children.values()) if len(no_split_children) > 0 else 0
    else:
        buffer = 0

    # Compute mean of final modules. In the first dict of module sizes, leaves are the parameters
    leaves = [n for n in module_sizes if len([p for p in module_sizes if n == "" or p.startswith(n + ".")]) == 0]
    module_sizes = {n: v for n, v in module_sizes.items() if n not in leaves}
    # Once removed, leaves are the final modules.
    leaves = [n for n in module_sizes if len([p for p in module_sizes if n == "" or p.startswith(n + ".")]) == 0]
    mean_leaves = int(sum([module_sizes[n] for n in leaves]) / max(len(leaves), 1))
    buffer = int(1.25 * max(buffer, mean_leaves))
    per_gpu += buffer

    # Sorted list of GPUs id (we may have some gpu ids not included in the our max_memory list - let's ignore them)
    gpus_idx_list = list(
        sorted(
            device_id for device_id, device_mem in max_memory.items() if isinstance(device_id, int) and device_mem > 0
        )
    )
    # The last device is left with max_memory just in case the buffer is not enough.
    for idx in gpus_idx_list[:-1]:
        max_memory[idx] = min(max_memory[0] if low_zero and idx == 0 else per_gpu, max_memory[idx])

    if low_zero:
        min_zero = max(0, module_sizes[""] - sum([max_memory[i] for i in range(1, num_devices)]))
        max_memory[0] = min(min_zero, max_memory[0])

    return max_memory


def calculate_maximum_sizes(model: torch.nn.Module):
    "Computes the total size of the model and its largest layer"
    sizes = compute_module_sizes(model)
    # `transformers` models store this information for us
    no_split_modules = getattr(model, "_no_split_modules", None)
    if no_split_modules is None:
        no_split_modules = []

    modules_to_treat = (
        list(model.named_parameters(recurse=False))
        + list(model.named_children())
        + list(model.named_buffers(recurse=False))
    )
    largest_layer = get_max_layer_size(modules_to_treat, sizes, no_split_modules)
    total_size = sizes[""]
    return total_size, largest_layer


def infer_auto_device_map(
    model: nn.Module,
    max_memory: Optional[Dict[Union[int, str], Union[int, str]]] = None,
    no_split_module_classes: Optional[List[str]] = None,
    dtype: Optional[Union[str, torch.dtype]] = None,
    special_dtypes: Optional[Dict[str, Union[str, torch.dtype]]] = None,
    verbose: bool = False,
    clean_result: bool = True,
    offload_buffers: bool = False,
):
    """
    Compute a device map for a given model giving priority to GPUs, then offload on CPU and finally offload to disk,
    such that:
    - we don't exceed the memory available of any of the GPU.
    - if offload to the CPU is needed, there is always room left on GPU 0 to put back the layer offloaded on CPU that
      has the largest size.
    - if offload to the CPU is needed,we don't exceed the RAM available on the CPU.
    - if offload to the disk is needed, there is always room left on the CPU to put back the layer offloaded on disk
      that has the largest size.

    <Tip>

    All computation is done analyzing sizes and dtypes of the model parameters. As a result, the model can be on the
    meta device (as it would if initialized within the `init_empty_weights` context manager).

    </Tip>

    Args:
        model (`torch.nn.Module`):
            The model to analyze.
        max_memory (`Dict`, *optional*):
            A dictionary device identifier to maximum memory. Will default to the maximum memory available if unset.
            Example: `max_memory={0: "1GB"}`.
        no_split_module_classes (`List[str]`, *optional*):
            A list of layer class names that should never be split across device (for instance any layer that has a
            residual connection).
        dtype (`str` or `torch.dtype`, *optional*):
            If provided, the weights will be converted to that type when loaded.
        special_dtypes (`Dict[str, Union[str, torch.device]]`, *optional*):
            If provided, special dtypes to consider for some specific weights (will override dtype used as default for
            all weights).
        verbose (`bool`, *optional*, defaults to `False`):
            Whether or not to provide debugging statements as the function builds the device_map.
        clean_result (`bool`, *optional*, defaults to `True`):
            Clean the resulting device_map by grouping all submodules that go on the same device together.
        offload_buffers (`bool`, *optional*, defaults to `False`):
            In the layers that are offloaded on the CPU or the hard drive, whether or not to offload the buffers as
            well as the parameters.
    """
    # Get default / clean up max_memory
    max_memory = get_max_memory(max_memory)
    if no_split_module_classes is None:
        no_split_module_classes = []
    elif not isinstance(no_split_module_classes, (list, tuple)):
        no_split_module_classes = [no_split_module_classes]

    devices = list(max_memory.keys())
    if "disk" not in devices:
        devices.append("disk")
    gpus = [device for device in devices if device not in ["cpu", "disk"]]

    # Devices that need to keep space for a potential offloaded layer.
    if "mps" in gpus:
        main_devices = ["mps"]
    elif len(gpus) > 0:
        main_devices = [gpus[0], "cpu"]
    else:
        main_devices = ["cpu"]

    module_sizes = compute_module_sizes(model, dtype=dtype, special_dtypes=special_dtypes)
    tied_parameters = find_tied_parameters(model)

    if check_tied_parameters_in_config(model) and len(tied_parameters) == 0:
        logger.warn(
            "The model weights are not tied. Please use the `tie_weights` method before using the `infer_auto_device` function."
        )

    device_map = OrderedDict()
    current_device = 0
    current_memory_used = 0
    device_memory_used = {}
    device_buffer_sizes = {}

    # Direct submodules and parameters
    modules_to_treat = (
        list(model.named_parameters(recurse=False))
        + list(model.named_children())
        + list(model.named_buffers(recurse=False))
    )
    # Initialize maximum largest layer, to know which space to keep in memory
    max_layer_size, max_layer_names = get_max_layer_size(modules_to_treat, module_sizes, no_split_module_classes)

    # Ready ? This is going to be a bit messy.
    while len(modules_to_treat) > 0:
        name, module = modules_to_treat.pop(0)
        if verbose:
            print(f"\nTreating module {name}.")
        # Max size in the remaining layers may have changed since we took one, so we maybe update it.
        max_layer_names = [n for n in max_layer_names if n != name and not n.startswith(name + ".")]
        if len(max_layer_names) == 0:
            max_layer_size, max_layer_names = get_max_layer_size(
                [(n, m) for n, m in modules_to_treat if isinstance(m, torch.nn.Module)],
                module_sizes,
                no_split_module_classes,
            )
        # Assess size needed
        module_size = module_sizes[name]

        # We keep relevant tied parameters only: one of the tied parameters in the group is inside the current module
        # and the other is not.
        # Note: If we are currently processing the name `compute.weight`, an other parameter named e.g. `compute.weight_submodule.parameter`
        # needs to be considered outside the current module, hence the check with additional dots.
        tied_param_goups = [
            tied_group
            for tied_group in tied_parameters
            if any(name + "." in k + "." for k in tied_group) and not all(name + "." in k + "." for k in tied_group)
        ]

        if verbose and len(tied_param_goups) > 0:
            print(f"  Found the relevant tied param groups {tied_param_goups}")

        # Then we keep track of all the parameters that are tied to the current module, but not in the current module
        tied_params = sum(
            [[p for p in tied_group if name + "." not in p + "."] for tied_group in tied_param_goups], []
        )

        if verbose and len(tied_params) > 0:
            print(f"  So those parameters need to be taken into account {tied_params}")

        device = devices[current_device]
        current_max_size = max_memory[device] if device != "disk" else None
        current_memory_reserved = 0
        # Reduce max size available by the largest layer.
        if devices[current_device] in main_devices:
            current_max_size = current_max_size - max_layer_size
            current_memory_reserved = max_layer_size
        # Case 1 -> We're too big!
        if current_max_size is not None and current_memory_used + module_size > current_max_size:
            # Split or not split?
            modules_children = (
                []
                if isinstance(module, nn.Parameter) or isinstance(module, torch.Tensor)
                else list(module.named_children())
            )
            if verbose:
                print(
                    f"Not enough space on {devices[current_device]} to put {name} (space available "
                    f"{current_max_size - current_memory_used}, module size {module_size})."
                )
            if len(modules_children) == 0 or module.__class__.__name__ in no_split_module_classes:
                # -> no split, we go to the next device
                if verbose:
                    print("This module cannot be split, going to the next device.")

                device_memory_used[device] = current_memory_used + current_memory_reserved
                current_device += 1
                modules_to_treat = [(name, module)] + modules_to_treat
                current_memory_used = 0
            else:
                # -> split, we replace the module studied by its children + parameters
                if verbose:
                    print(f"Splitting {name}.")
                modules_children = list(module.named_parameters(recurse=False)) + modules_children
                modules_to_treat = [(f"{name}.{n}", v) for n, v in modules_children] + modules_to_treat
                # Update the max layer size.
                max_layer_size, max_layer_names = get_max_layer_size(
                    [(n, m) for n, m in modules_to_treat if isinstance(m, torch.nn.Module)],
                    module_sizes,
                    no_split_module_classes,
                )

        # Case 2, it fits! We're not entirely out of the wood though, because we may have some tied parameters.
        elif len(tied_params) > 0:
            # First locate all tied modules
            tied_module_names = []
            tied_modules = []
            for tied_param in tied_params:
                tied_module_index = [i for i, (n, _) in enumerate(modules_to_treat) if n in tied_param][0]
                tied_module_names.append(modules_to_treat[tied_module_index][0])
                tied_modules.append(modules_to_treat[tied_module_index][1])
            if verbose:
                print(
                    f"  It looks like {name} is going to fit on {devices[current_device]} but we have tied "
                    f"parameters to account for.\n  - Names {tied_params}\n  - Module names {tied_module_names}"
                )

            # Let's see if it all fits first
            module_size_with_ties = module_size
            for tied_param, tied_module_name in zip(tied_params, tied_module_names):
                module_size_with_ties += module_sizes[tied_module_name] - module_sizes[tied_param]

            if current_max_size is None or current_memory_used + module_size_with_ties <= current_max_size:
                # We really really fit!
                if verbose:
                    print(f"Putting {name} and {tied_module_names} on {devices[current_device]}.")
                current_memory_used += module_size_with_ties
                device_map[name] = devices[current_device]
                for tied_module_name in tied_module_names:
                    if tied_module_name in [m[0] for m in modules_to_treat]:
                        # The module may have been removed by a previous iteration of this loop.
                        tied_module_index = [i for i, (n, _) in enumerate(modules_to_treat) if n == tied_module_name][
                            0
                        ]
                        modules_to_treat.pop(tied_module_index)
                    device_map[tied_module_name] = devices[current_device]

                if not offload_buffers and isinstance(module, nn.Module):
                    current_buffer_size = compute_module_total_buffer_size(
                        module, dtype=dtype, special_dtypes=special_dtypes
                    )
                    device_buffer_sizes[device] = device_buffer_sizes.get(device, 0) + current_buffer_size

            else:
                # We don't fit with the tied modules. Next question is: can we split one of the tied modules to make it
                # smaller or do we need to go on the next device?
                if verbose:
                    print(
                        f"Not enough space on {devices[current_device]} to put {name} and {tied_module_names} (space "
                        f"available {current_max_size - current_memory_used}, needed size {module_size_with_ties})."
                    )
                split_happened = False
                for tied_module_name, tied_module in zip(tied_module_names, tied_modules):
                    tied_module_children = list(tied_module.named_children())
                    if len(tied_module_children) == 0 or tied_module.__class__.__name__ in no_split_module_classes:
                        # can't break this one.
                        continue

                    if verbose:
                        print(f"Splitting {tied_module_name}.")
                    tied_module_children = list(tied_module.named_parameters(recurse=False)) + tied_module_children
                    tied_module_children = [(f"{tied_module_name}.{n}", v) for n, v in tied_module_children]
                    tied_module_index = [i for i, (n, _) in enumerate(modules_to_treat) if n == tied_module_name][0]

                    modules_to_treat = (
                        [(name, module)]
                        + modules_to_treat[:tied_module_index]
                        + tied_module_children
                        + modules_to_treat[tied_module_index + 1 :]
                    )
                    # Update the max layer size.
                    max_layer_size, max_layer_names = get_max_layer_size(
                        [(n, m) for n, m in modules_to_treat if isinstance(m, torch.nn.Module)],
                        module_sizes,
                        no_split_module_classes,
                    )
                    split_happened = True
                    break

                if not split_happened:
                    # If the tied module is not split, we go to the next device
                    if verbose:
                        print("None of the tied module can be split, going to the next device.")

                    device_memory_used[device] = current_memory_used + current_memory_reserved
                    current_device += 1
                    modules_to_treat = [(name, module)] + modules_to_treat
                    current_memory_used = 0

        else:
            if verbose:
                if current_max_size is None:
                    print(f"Putting {name} (size={module_size}) on {devices[current_device]}.")
                else:
                    print(
                        f"Putting {name} (size={module_size}) on {devices[current_device]} "
                        f"(available={current_max_size - current_memory_used})."
                    )
            current_memory_used += module_size
            device_memory_used[device] = current_memory_used + current_memory_reserved
            device_map[name] = devices[current_device]

            if not offload_buffers and isinstance(module, nn.Module):
                current_buffer_size = compute_module_total_buffer_size(
                    module, dtype=dtype, special_dtypes=special_dtypes
                )
                device_buffer_sizes[device] = device_buffer_sizes.get(device, 0) + current_buffer_size

    if clean_result:
        device_map = clean_device_map(device_map)

    non_gpu_buffer_size = device_buffer_sizes.get("cpu", 0) + device_buffer_sizes.get("disk", 0)
    if non_gpu_buffer_size > 0 and not offload_buffers:
        is_buffer_fit_any_gpu = False
        for gpu_device, gpu_max_memory in max_memory.items():
            if gpu_device == "cpu" or gpu_device == "disk":
                continue

            if not is_buffer_fit_any_gpu:
                gpu_memory_used = device_memory_used.get(gpu_device, 0)

                if gpu_max_memory >= non_gpu_buffer_size + gpu_memory_used:
                    is_buffer_fit_any_gpu = True

        if len(gpus) > 0 and not is_buffer_fit_any_gpu:
            warnings.warn(
                f"Current model requires {non_gpu_buffer_size} bytes of buffer for offloaded layers, which seems does "
                f"not fit any GPU's remaining memory. If you are experiencing a OOM later, please consider using "
                f"offload_buffers=True."
            )

    return device_map


def check_device_map(model: nn.Module, device_map: Dict[str, Union[int, str, torch.device]]):
    """
    Checks a device map covers everything in a given model.

    Args:
        model (`torch.nn.Module`): The model to check the device map against.
        device_map (`Dict[str, Union[int, str, torch.device]]`): The device map to check.
    """
    all_model_tensors = [name for name, _ in model.state_dict().items()]
    for module_name in device_map.keys():
        if module_name == "":
            all_model_tensors.clear()
            break
        else:
            all_model_tensors = [
                name
                for name in all_model_tensors
                if not name == module_name and not name.startswith(module_name + ".")
            ]
    if len(all_model_tensors) > 0:
        non_covered_params = ", ".join(all_model_tensors)
        raise ValueError(
            f"The device_map provided does not give any device for the following parameters: {non_covered_params}"
        )


def load_state_dict(checkpoint_file, device_map=None):
    """
    Load a checkpoint from a given file. If the checkpoint is in the safetensors format and a device map is passed, the
    weights can be fast-loaded directly on the GPU.

    Args:
        checkpoint_file (`str`): The path to the checkpoint to load.
        device_map (`Dict[str, Union[int, str, torch.device]]`, *optional*):
            A map that specifies where each submodule should go. It doesn't need to be refined to each parameter/buffer
            name, once a given module name is inside, every submodule of it will be sent to the same device.
    """
    if checkpoint_file.endswith(".safetensors"):
        with safe_open(checkpoint_file, framework="pt") as f:
            metadata = f.metadata()
            weight_names = f.keys()

        if metadata is None:
            logger.warn(
                f"The safetensors archive passed at {checkpoint_file} does not contain metadata. "
                "Make sure to save your model with the `save_pretrained` method. Defaulting to 'pt' metadata."
            )
            metadata = {"format": "pt"}

        if metadata.get("format") not in ["pt", "tf", "flax"]:
            raise OSError(
                f"The safetensors archive passed at {checkpoint_file} does not contain the valid metadata. Make sure "
                "you save your model with the `save_pretrained` method."
            )
        elif metadata["format"] != "pt":
            raise ValueError(f"The checkpoint passed was saved with {metadata['format']}, we need a the pt format.")
        if device_map is None:
            return safe_load_file(checkpoint_file)
        else:
            # if we only have one device we can load everything directly
            if len(set(device_map.values())) == 1:
                return safe_load_file(checkpoint_file, device=list(device_map.values())[0])

            devices = list(set(device_map.values()) - {"disk"})
            # cpu device should always exist as fallback option
            if "cpu" not in devices:
                devices.append("cpu")

            # For each device, get the weights that go there
            device_weights = {device: [] for device in devices}
            for module_name, device in device_map.items():
                if device in devices:
                    device_weights[device].extend(
                        [k for k in weight_names if k == module_name or k.startswith(module_name + ".")]
                    )

            # all weights that haven't defined a device should be loaded on CPU
            device_weights["cpu"].extend([k for k in weight_names if k not in sum(device_weights.values(), [])])
            tensors = {}
            if is_tqdm_available():
                progress_bar = tqdm(
                    main_process_only=False,
                    total=sum([len(device_weights[device]) for device in devices]),
                    unit="w",
                    smoothing=0,
                    leave=False,
                )
            else:
                progress_bar = None
            for device in devices:
                target_device = device

                if is_xpu_available():
                    current_safetensors_version = packaging.version.parse(importlib.metadata.version("safetensors"))

                    if compare_versions(current_safetensors_version, "<", "0.4.2"):
                        raise ModuleNotFoundError(
                            f"You need at least safetensors 0.4.2 for Intel GPU, while you have {current_safetensors_version}"
                        )

                    if isinstance(device, int):
                        target_device = f"xpu:{device}"

                with safe_open(checkpoint_file, framework="pt", device=target_device) as f:
                    for key in device_weights[device]:
                        if progress_bar is not None:
                            progress_bar.set_postfix(dev=device, refresh=False)
                            progress_bar.set_description(key)
                        tensors[key] = f.get_tensor(key)
                        if progress_bar is not None:
                            progress_bar.update()
            if progress_bar is not None:
                progress_bar.close()

            return tensors
    else:
        return torch.load(checkpoint_file, map_location=torch.device("cpu"))


def get_state_dict_offloaded_model(model: nn.Module):
    """
    Returns the state dictionary for an offloaded model via iterative onloading

    Args:
        model (`torch.nn.Module`):
            The offloaded model we want to save
    """
    from ..hooks import AlignDevicesHook

    state_dict = {}
    placeholders = set()
    for name, module in model.named_modules():
        if name == "":
            continue
        if hasattr(module, "_hf_hook") and isinstance(module._hf_hook, AlignDevicesHook) and module._hf_hook.offload:
            original_device = module._hf_hook.execution_device
            # assign hook execution device to cpu
            module._hf_hook.execution_device = "cpu"
            # onload meta tensors to execution device
            try:
                module._hf_hook.pre_forward(module)
            except MemoryError:
                raise MemoryError("Offloaded module must fit in CPU memory to call save_model!") from None
            module_state_dict = module.state_dict()
            # offload meta tensors from cpu
            module._hf_hook.post_forward(module, torch.tensor([]))
            # re-assign hook to original execution device
            module._hf_hook.execution_device = original_device
        else:
            module_state_dict = module.state_dict()

        for key in module_state_dict:
            # ignore placeholder parameters that are still on the meta device
            if module_state_dict[key].device == torch.device("meta"):
                placeholders.add(name + f".{key}")
                continue
            params = module_state_dict[key]
            state_dict[name + f".{key}"] = params
    for key in placeholders.copy():
        if key in state_dict:
            placeholders.remove(key)
    if placeholders:
        logger.warning(f"The following tensors were not saved because they were still on meta device: {placeholders}")

    return state_dict


def load_checkpoint_in_model(
    model: nn.Module,
    checkpoint: Union[str, os.PathLike],
    device_map: Optional[Dict[str, Union[int, str, torch.device]]] = None,
    offload_folder: Optional[Union[str, os.PathLike]] = None,
    dtype: Optional[Union[str, torch.dtype]] = None,
    offload_state_dict: bool = False,
    offload_buffers: bool = False,
    keep_in_fp32_modules: List[str] = None,
    offload_8bit_bnb: bool = False,
    strict: bool = False,
):
    """
    Loads a (potentially sharded) checkpoint inside a model, potentially sending weights to a given device as they are
    loaded.

    <Tip warning={true}>

    Once loaded across devices, you still need to call [`dispatch_model`] on your model to make it able to run. To
    group the checkpoint loading and dispatch in one single call, use [`load_checkpoint_and_dispatch`].

    </Tip>

    Args:
        model (`torch.nn.Module`):
            The model in which we want to load a checkpoint.
        checkpoint (`str` or `os.PathLike`):
            The folder checkpoint to load. It can be:
            - a path to a file containing a whole model state dict
            - a path to a `.json` file containing the index to a sharded checkpoint
            - a path to a folder containing a unique `.index.json` file and the shards of a checkpoint.
            - a path to a folder containing a unique pytorch_model.bin or a model.safetensors file.
        device_map (`Dict[str, Union[int, str, torch.device]]`, *optional*):
            A map that specifies where each submodule should go. It doesn't need to be refined to each parameter/buffer
            name, once a given module name is inside, every submodule of it will be sent to the same device.
        offload_folder (`str` or `os.PathLike`, *optional*):
            If the `device_map` contains any value `"disk"`, the folder where we will offload weights.
        dtype (`str` or `torch.dtype`, *optional*):
            If provided, the weights will be converted to that type when loaded.
        offload_state_dict (`bool`, *optional*, defaults to `False`):
            If `True`, will temporarily offload the CPU state dict on the hard drive to avoid getting out of CPU RAM if
            the weight of the CPU state dict + the biggest shard does not fit.
        offload_buffers (`bool`, *optional*, defaults to `False`):
            Whether or not to include the buffers in the weights offloaded to disk.
        keep_in_fp32_modules(`List[str]`, *optional*):
            A list of the modules that we keep in `torch.float32` dtype.
        offload_8bit_bnb (`bool`, *optional*):
            Whether or not to enable offload of 8-bit modules on cpu/disk.
        strict (`bool`, *optional*, defaults to `False`):
            Whether to strictly enforce that the keys in the checkpoint state_dict match the keys of the model's
            state_dict.

    """
    if offload_8bit_bnb:
        from .bnb import quantize_and_offload_8bit

    tied_params = find_tied_parameters(model)

    if check_tied_parameters_in_config(model) and len(tied_params) == 0:
        logger.warn(
            "The model weights are not tied. Please use the `tie_weights` method before using the `infer_auto_device` function."
        )
    if device_map is not None:
        check_tied_parameters_on_same_device(tied_params, device_map)

    if offload_folder is None and device_map is not None and "disk" in device_map.values():
        raise ValueError(
            "At least one of the model submodule will be offloaded to disk, please pass along an `offload_folder`."
        )
    elif offload_folder is not None and device_map is not None and "disk" in device_map.values():
        os.makedirs(offload_folder, exist_ok=True)

    if isinstance(dtype, str):
        # We accept "torch.float16" or just "float16"
        dtype = dtype.replace("torch.", "")
        dtype = getattr(torch, dtype)

    checkpoint_files = None
    index_filename = None
    if os.path.isfile(checkpoint):
        if str(checkpoint).endswith(".json"):
            index_filename = checkpoint
        else:
            checkpoint_files = [checkpoint]
    elif os.path.isdir(checkpoint):
        # check if the whole state dict is present
        potential_state_bin = [f for f in os.listdir(checkpoint) if f == WEIGHTS_NAME]
        potential_state_safetensor = [f for f in os.listdir(checkpoint) if f == SAFE_WEIGHTS_NAME]
        if len(potential_state_bin) == 1:
            checkpoint_files = [os.path.join(checkpoint, potential_state_bin[0])]
        elif len(potential_state_safetensor) == 1:
            checkpoint_files = [os.path.join(checkpoint, potential_state_safetensor[0])]
        else:
            # otherwise check for sharded checkpoints
            potential_index = [f for f in os.listdir(checkpoint) if f.endswith(".index.json")]
            if len(potential_index) == 0:
                raise ValueError(
                    f"{checkpoint} is not a folder containing a `.index.json` file or a {WEIGHTS_NAME} or a {SAFE_WEIGHTS_NAME} file"
                )
            elif len(potential_index) == 1:
                index_filename = os.path.join(checkpoint, potential_index[0])
            else:
                raise ValueError(
                    f"{checkpoint} containing more than one `.index.json` file, delete the irrelevant ones."
                )
    else:
        raise ValueError(
            "`checkpoint` should be the path to a file containing a whole state dict, or the index of a sharded "
            f"checkpoint, or a folder containing a sharded checkpoint or the whole state dict, but got {checkpoint}."
        )

    if index_filename is not None:
        checkpoint_folder = os.path.split(index_filename)[0]
        with open(index_filename) as f:
            index = json.loads(f.read())

        if "weight_map" in index:
            index = index["weight_map"]
        checkpoint_files = sorted(list(set(index.values())))
        checkpoint_files = [os.path.join(checkpoint_folder, f) for f in checkpoint_files]

    # Logic for missing/unexepected keys goes here.

    offload_index = {}
    if offload_state_dict:
        state_dict_folder = tempfile.mkdtemp()
        state_dict_index = {}

    unexpected_keys = set()
    model_keys = set(model.state_dict().keys())
    buffer_names = [name for name, _ in model.named_buffers()]
    for checkpoint_file in checkpoint_files:
        loaded_checkpoint = load_state_dict(checkpoint_file, device_map=device_map)
        if device_map is None:
            model.load_state_dict(loaded_checkpoint, strict=strict)
            unexpected_keys.update(set(loaded_checkpoint.keys()) - model_keys)
        else:
            for param_name, param in loaded_checkpoint.items():
                # skip SCB parameter (for 8-bit serialization)
                if "SCB" in param_name:
                    continue

                if param_name not in model_keys:
                    unexpected_keys.add(param_name)
                    if not strict:
                        continue  # Skip loading this parameter.

                module_name = param_name

                while len(module_name) > 0 and module_name not in device_map:
                    module_name = ".".join(module_name.split(".")[:-1])
                if module_name == "" and "" not in device_map:
                    # TODO: group all errors and raise at the end.
                    raise ValueError(f"{param_name} doesn't have any device set.")
                param_device = device_map[module_name]
                new_dtype = dtype
                if dtype is not None and torch.is_floating_point(param):
                    if keep_in_fp32_modules is not None and dtype == torch.float16:
                        proceed = False
                        for key in keep_in_fp32_modules:
                            if ((key in param_name) and (key + "." in param_name)) or key == param_name:
                                proceed = True
                                break
                        if proceed:
                            new_dtype = torch.float32

                if "weight" in param_name and param_name.replace("weight", "SCB") in loaded_checkpoint.keys():
                    if param.dtype == torch.int8:
                        fp16_statistics = loaded_checkpoint[param_name.replace("weight", "SCB")]
                else:
                    fp16_statistics = None

                if param_device == "disk":
                    if offload_buffers or param_name not in buffer_names:
                        if new_dtype is None:
                            new_dtype = param.dtype
                        if offload_8bit_bnb:
                            quantize_and_offload_8bit(
                                model, param, param_name, new_dtype, offload_folder, offload_index, fp16_statistics
                            )
                            continue
                        else:
                            set_module_tensor_to_device(model, param_name, "meta", dtype=new_dtype)
                        offload_weight(param, param_name, offload_folder, index=offload_index)
                elif param_device == "cpu" and offload_state_dict:
                    if new_dtype is None:
                        new_dtype = param.dtype
                    if offload_8bit_bnb:
                        quantize_and_offload_8bit(
                            model, param, param_name, new_dtype, state_dict_folder, state_dict_index, fp16_statistics
                        )
                    else:
                        set_module_tensor_to_device(model, param_name, "meta", dtype=new_dtype)
                        offload_weight(param, param_name, state_dict_folder, index=state_dict_index)
                else:
                    set_module_tensor_to_device(
                        model,
                        param_name,
                        param_device,
                        value=param,
                        dtype=new_dtype,
                        fp16_statistics=fp16_statistics,
                    )

        # Force Python to clean up.
        del loaded_checkpoint
        gc.collect()

    if not strict and len(unexpected_keys) > 0:
        logger.warning(
            f"Some weights of the model checkpoint at {checkpoint} were not used when"
            f" initializing {model.__class__.__name__}: {unexpected_keys}. This may or may not be an issue - make sure that the checkpoint does not have unnecessary parameters, or that the model definition correctly corresponds to the checkpoint."
        )

    save_offload_index(offload_index, offload_folder)

    # Load back offloaded state dict on CPU
    if offload_state_dict:
        load_offloaded_weights(model, state_dict_index, state_dict_folder)
        shutil.rmtree(state_dict_folder)

    retie_parameters(model, tied_params)


def get_mixed_precision_context_manager(native_amp: bool = False, autocast_kwargs: AutocastKwargs = None):
    """
    Return a context manager for autocasting mixed precision

    Args:
        native_amp (`bool`, *optional*, defaults to False):
            Whether mixed precision is actually enabled.
        cache_enabled (`bool`, *optional*, defaults to True):
            Whether the weight cache inside autocast should be enabled.
    """
    state = AcceleratorState()
    if autocast_kwargs is None:
        autocast_kwargs = {}
    else:
        autocast_kwargs = autocast_kwargs.to_kwargs()
    if native_amp:
        device_type = (
            "cuda"
            if (state.distributed_type == DistributedType.XLA and is_torch_xla_available(check_is_gpu=True))
            else state.device.type
        )
        if state.mixed_precision == "fp16":
            return torch.autocast(device_type=device_type, dtype=torch.float16, **autocast_kwargs)
        elif state.mixed_precision == "bf16" and state.distributed_type in [
            DistributedType.NO,
            DistributedType.MULTI_CPU,
            DistributedType.MULTI_GPU,
            DistributedType.MULTI_MLU,
            DistributedType.MULTI_NPU,
            DistributedType.MULTI_XPU,
            DistributedType.FSDP,
            DistributedType.XLA,
        ]:
            return torch.autocast(device_type=device_type, dtype=torch.bfloat16, **autocast_kwargs)
        else:
            return torch.autocast(device_type=device_type, **autocast_kwargs)
    else:
        return contextlib.nullcontext()