# coding=utf-8

# Copyright 2024 The HuggingFace Inc. team.

# Copyright (c) 2022, 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 inspect

import itertools

import os

import re

from collections import OrderedDict

from functools import partial

from pathlib import Path

from typing import Any, Callable, List, Optional, Tuple, Union

import safetensors

import torch

from huggingface_hub import create_repo

from huggingface_hub.utils import validate_hf_hub_args

from torch import Tensor, nn

from .. import __version__

from ..utils import (

CONFIG_NAME,

FLAX_WEIGHTS_NAME,

SAFETENSORS_FILE_EXTENSION,

SAFETENSORS_WEIGHTS_NAME,

WEIGHTS_NAME,

_add_variant,

_get_model_file,

deprecate,

is_accelerate_available,

is_torch_version,

logging,

)

from ..utils.hub_utils import PushToHubMixin, load_or_create_model_card, populate_model_card

logger = logging.get_logger(__name__)

if is_torch_version(">=", "1.9.0"):

_LOW_CPU_MEM_USAGE_DEFAULT = True

else:

_LOW_CPU_MEM_USAGE_DEFAULT = False

if is_accelerate_available():

import accelerate

from accelerate import infer_auto_device_map

from accelerate.utils import get_balanced_memory, get_max_memory, set_module_tensor_to_device

from accelerate.utils.versions import is_torch_version

def get_parameter_device(parameter: torch.nn.Module) -> torch.device:

try:

parameters_and_buffers = itertools.chain(parameter.parameters(), parameter.buffers())

return next(parameters_and_buffers).device

except StopIteration:

# For torch.nn.DataParallel compatibility in PyTorch 1.5

def find_tensor_attributes(module: torch.nn.Module) -> List[Tuple[str, Tensor]]:

tuples = [(k, v) for k, v in module.__dict__.items() if torch.is_tensor(v)]

return tuples

gen = parameter._named_members(get_members_fn=find_tensor_attributes)

first_tuple = next(gen)

return first_tuple[1].device

def get_parameter_dtype(parameter: torch.nn.Module) -> torch.dtype:

try:

params = tuple(parameter.parameters())

if len(params) > 0:

return params[0].dtype

buffers = tuple(parameter.buffers())

if len(buffers) > 0:

return buffers[0].dtype

except StopIteration:

# For torch.nn.DataParallel compatibility in PyTorch 1.5

def find_tensor_attributes(module: torch.nn.Module) -> List[Tuple[str, Tensor]]:

tuples = [(k, v) for k, v in module.__dict__.items() if torch.is_tensor(v)]

return tuples

gen = parameter._named_members(get_members_fn=find_tensor_attributes)

first_tuple = next(gen)

return first_tuple[1].dtype

# Adapted from `transformers` (see modeling_utils.py)

def _determine_device_map(model: "ModelMixin", device_map, max_memory, torch_dtype):

if isinstance(device_map, str):

no_split_modules = model._get_no_split_modules(device_map)

device_map_kwargs = {"no_split_module_classes": no_split_modules}

if device_map != "sequential":

max_memory = get_balanced_memory(

model,

dtype=torch_dtype,

low_zero=(device_map == "balanced_low_0"),

max_memory=max_memory,

**device_map_kwargs,

)

else:

max_memory = get_max_memory(max_memory)

device_map_kwargs["max_memory"] = max_memory

device_map = infer_auto_device_map(model, dtype=torch_dtype, **device_map_kwargs)

return device_map

def load_state_dict(checkpoint_file: Union[str, os.PathLike], variant: Optional[str] = None):

"""

Reads a checkpoint file, returning properly formatted errors if they arise.

"""

try:

file_extension = os.path.basename(checkpoint_file).split(".")[-1]

if file_extension == SAFETENSORS_FILE_EXTENSION:

return safetensors.torch.load_file(checkpoint_file, device="cpu")

else:

weights_only_kwarg = {"weights_only": True} if is_torch_version(">=", "1.13") else {}

return torch.load(

checkpoint_file,

map_location="cpu",

**weights_only_kwarg,

)

except Exception as e:

try:

with open(checkpoint_file) as f:

if f.read().startswith("version"):

raise OSError(

"You seem to have cloned a repository without having git-lfs installed. Please install "

"git-lfs and run `git lfs install` followed by `git lfs pull` in the folder "

"you cloned."

)

else:

raise ValueError(

f"Unable to locate the file {checkpoint_file} which is necessary to load this pretrained "

"model. Make sure you have saved the model properly."

) from e

except (UnicodeDecodeError, ValueError):

raise OSError(

f"Unable to load weights from checkpoint file for '{checkpoint_file}' " f"at '{checkpoint_file}'. "

)

def load_model_dict_into_meta(

model,

state_dict: OrderedDict,

device: Optional[Union[str, torch.device]] = None,

dtype: Optional[Union[str, torch.dtype]] = None,

model_name_or_path: Optional[str] = None,

) -> List[str]:

device = device or torch.device("cpu")

dtype = dtype or torch.float32

accepts_dtype = "dtype" in set(inspect.signature(set_module_tensor_to_device).parameters.keys())

unexpected_keys = []

empty_state_dict = model.state_dict()

for param_name, param in state_dict.items():

if param_name not in empty_state_dict:

unexpected_keys.append(param_name)

continue

if empty_state_dict[param_name].shape != param.shape:

model_name_or_path_str = f"{model_name_or_path} " if model_name_or_path is not None else ""

raise ValueError(

f"Cannot load {model_name_or_path_str}because {param_name} expected shape {empty_state_dict[param_name]}, but got {param.shape}. If you want to instead overwrite randomly initialized weights, please make sure to pass both `low_cpu_mem_usage=False` and `ignore_mismatched_sizes=True`. For more information, see also: https://github.com/huggingface/diffusers/issues/1619#issuecomment-1345604389 as an example."

)

if accepts_dtype:

set_module_tensor_to_device(model, param_name, device, value=param, dtype=dtype)

else:

set_module_tensor_to_device(model, param_name, device, value=param)

return unexpected_keys

def _load_state_dict_into_model(model_to_load, state_dict: OrderedDict) -> List[str]:

# Convert old format to new format if needed from a PyTorch state_dict

# copy state_dict so _load_from_state_dict can modify it

state_dict = state_dict.copy()

error_msgs = []

# PyTorch's `_load_from_state_dict` does not copy parameters in a module's descendants

# so we need to apply the function recursively.

def load(module: torch.nn.Module, prefix: str = ""):

args = (state_dict, prefix, {}, True, [], [], error_msgs)

module._load_from_state_dict(*args)

for name, child in module._modules.items():

if child is not None:

load(child, prefix + name + ".")

load(model_to_load)

return error_msgs

class ModelMixin(torch.nn.Module, PushToHubMixin):

r"""

Base class for all models.

[`ModelMixin`] takes care of storing the model configuration and provides methods for loading, downloading and

saving models.

- **config_name** ([`str`]) -- Filename to save a model to when calling [`~models.ModelMixin.save_pretrained`].

"""

config_name = CONFIG_NAME

_automatically_saved_args = ["_diffusers_version", "_class_name", "_name_or_path"]

_supports_gradient_checkpointing = False

_keys_to_ignore_on_load_unexpected = None

_no_split_modules = None

def __init__(self):

super().__init__()

def __getattr__(self, name: str) -> Any:

"""The only reason we overwrite `getattr` here is to gracefully deprecate accessing

config attributes directly. See https://github.com/huggingface/diffusers/pull/3129 We need to overwrite

__getattr__ here in addition so that we don't trigger `torch.nn.Module`'s __getattr__':

https://pytorch.org/docs/stable/_modules/torch/nn/modules/module.html#Module

"""

is_in_config = "_internal_dict" in self.__dict__ and hasattr(self.__dict__["_internal_dict"], name)

is_attribute = name in self.__dict__

if is_in_config and not is_attribute:

deprecation_message = f"Accessing config attribute `{name}` directly via '{type(self).__name__}' object attribute is deprecated. Please access '{name}' over '{type(self).__name__}'s config object instead, e.g. 'unet.config.{name}'."

deprecate("direct config name access", "1.0.0", deprecation_message, standard_warn=False, stacklevel=3)

return self._internal_dict[name]

# call PyTorch's https://pytorch.org/docs/stable/_modules/torch/nn/modules/module.html#Module

return super().__getattr__(name)

@property

def is_gradient_checkpointing(self) -> bool:

"""

Whether gradient checkpointing is activated for this model or not.

"""

return any(hasattr(m, "gradient_checkpointing") and m.gradient_checkpointing for m in self.modules())

def enable_gradient_checkpointing(self) -> None:

"""

Activates gradient checkpointing for the current model (may be referred to as *activation checkpointing* or

*checkpoint activations* in other frameworks).

"""

if not self._supports_gradient_checkpointing:

raise ValueError(f"{self.__class__.__name__} does not support gradient checkpointing.")

self.apply(partial(self._set_gradient_checkpointing, value=True))

def disable_gradient_checkpointing(self) -> None:

"""

Deactivates gradient checkpointing for the current model (may be referred to as *activation checkpointing* or

*checkpoint activations* in other frameworks).

"""

if self._supports_gradient_checkpointing:

self.apply(partial(self._set_gradient_checkpointing, value=False))

def set_use_npu_flash_attention(self, valid: bool) -> None:

r"""

Set the switch for the npu flash attention.

"""

def fn_recursive_set_npu_flash_attention(module: torch.nn.Module):

if hasattr(module, "set_use_npu_flash_attention"):

module.set_use_npu_flash_attention(valid)

for child in module.children():

fn_recursive_set_npu_flash_attention(child)

for module in self.children():

if isinstance(module, torch.nn.Module):

fn_recursive_set_npu_flash_attention(module)

def enable_npu_flash_attention(self) -> None:

r"""

Enable npu flash attention from torch_npu

"""

self.set_use_npu_flash_attention(True)

def disable_npu_flash_attention(self) -> None:

r"""

disable npu flash attention from torch_npu

"""

self.set_use_npu_flash_attention(False)

def set_use_memory_efficient_attention_xformers(

self, valid: bool, attention_op: Optional[Callable] = None

) -> None:

# Recursively walk through all the children.

# Any children which exposes the set_use_memory_efficient_attention_xformers method

# gets the message

def fn_recursive_set_mem_eff(module: torch.nn.Module):

if hasattr(module, "set_use_memory_efficient_attention_xformers"):

module.set_use_memory_efficient_attention_xformers(valid, attention_op)

for child in module.children():

fn_recursive_set_mem_eff(child)

for module in self.children():

if isinstance(module, torch.nn.Module):

fn_recursive_set_mem_eff(module)

def enable_xformers_memory_efficient_attention(self, attention_op: Optional[Callable] = None) -> None:

r"""

Enable memory efficient attention from [xFormers](https://facebookresearch.github.io/xformers/).

When this option is enabled, you should observe lower GPU memory usage and a potential speed up during

inference. Speed up during training is not guaranteed.

<Tip warning={true}>

⚠️ When memory efficient attention and sliced attention are both enabled, memory efficient attention takes

precedent.

</Tip>

Parameters:

attention_op (`Callable`, *optional*):

Override the default `None` operator for use as `op` argument to the

[`memory_efficient_attention()`](https://facebookresearch.github.io/xformers/components/ops.html#xformers.ops.memory_efficient_attention)

function of xFormers.

Examples:

```py

>>> import torch

>>> from diffusers import UNet2DConditionModel

>>> from xformers.ops import MemoryEfficientAttentionFlashAttentionOp

>>> model = UNet2DConditionModel.from_pretrained(

... "stabilityai/stable-diffusion-2-1", subfolder="unet", torch_dtype=torch.float16

... )

>>> model = model.to("cuda")

>>> model.enable_xformers_memory_efficient_attention(attention_op=MemoryEfficientAttentionFlashAttentionOp)

```

"""

self.set_use_memory_efficient_attention_xformers(True, attention_op)

def disable_xformers_memory_efficient_attention(self) -> None:

r"""

Disable memory efficient attention from [xFormers](https://facebookresearch.github.io/xformers/).

"""

self.set_use_memory_efficient_attention_xformers(False)

def save_pretrained(

self,

save_directory: Union[str, os.PathLike],

is_main_process: bool = True,

save_function: Optional[Callable] = None,

safe_serialization: bool = True,

variant: Optional[str] = None,

push_to_hub: bool = False,

**kwargs,

):

"""

Save a model and its configuration file to a directory so that it can be reloaded using the

[`~models.ModelMixin.from_pretrained`] class method.

Arguments:

save_directory (`str` or `os.PathLike`):

Directory to save a model and its configuration file to. Will be created if it doesn't exist.

is_main_process (`bool`, *optional*, defaults to `True`):

Whether the process calling this is the main process or not. Useful during distributed training and you

need to call this function on all processes. In this case, set `is_main_process=True` only on the main

process to avoid race conditions.

save_function (`Callable`):

The function to use to save the state dictionary. Useful during distributed training when you need to

replace `torch.save` with another method. Can be configured with the environment variable

`DIFFUSERS_SAVE_MODE`.

safe_serialization (`bool`, *optional*, defaults to `True`):

Whether to save the model using `safetensors` or the traditional PyTorch way with `pickle`.

variant (`str`, *optional*):

If specified, weights are saved in the format `pytorch_model.<variant>.bin`.

push_to_hub (`bool`, *optional*, defaults to `False`):

Whether or not to push your model to the Hugging Face Hub after saving it. You can specify the

repository you want to push to with `repo_id` (will default to the name of `save_directory` in your

namespace).

kwargs (`Dict[str, Any]`, *optional*):

Additional keyword arguments passed along to the [`~utils.PushToHubMixin.push_to_hub`] method.

"""

if os.path.isfile(save_directory):

logger.error(f"Provided path ({save_directory}) should be a directory, not a file")

return

os.makedirs(save_directory, exist_ok=True)

if push_to_hub:

commit_message = kwargs.pop("commit_message", None)

private = kwargs.pop("private", False)

create_pr = kwargs.pop("create_pr", False)

token = kwargs.pop("token", None)

repo_id = kwargs.pop("repo_id", save_directory.split(os.path.sep)[-1])

repo_id = create_repo(repo_id, exist_ok=True, private=private, token=token).repo_id

# Only save the model itself if we are using distributed training

model_to_save = self

# Attach architecture to the config

# Save the config

if is_main_process:

model_to_save.save_config(save_directory)

# Save the model

state_dict = model_to_save.state_dict()

weights_name = SAFETENSORS_WEIGHTS_NAME if safe_serialization else WEIGHTS_NAME

weights_name = _add_variant(weights_name, variant)

# Save the model

if safe_serialization:

safetensors.torch.save_file(

state_dict, Path(save_directory, weights_name).as_posix(), metadata={"format": "pt"}

)

else:

torch.save(state_dict, Path(save_directory, weights_name).as_posix())

logger.info(f"Model weights saved in {Path(save_directory, weights_name).as_posix()}")

if push_to_hub:

# Create a new empty model card and eventually tag it

model_card = load_or_create_model_card(repo_id, token=token)

model_card = populate_model_card(model_card)

model_card.save(Path(save_directory, "README.md").as_posix())

self._upload_folder(

save_directory,

repo_id,

token=token,

commit_message=commit_message,

create_pr=create_pr,

)

@classmethod

@validate_hf_hub_args

def from_pretrained(cls, pretrained_model_name_or_path: Optional[Union[str, os.PathLike]], **kwargs):

r"""

Instantiate a pretrained PyTorch model from a pretrained model configuration.

The model is set in evaluation mode - `model.eval()` - by default, and dropout modules are deactivated. To

train the model, set it back in training mode with `model.train()`.

Parameters:

pretrained_model_name_or_path (`str` or `os.PathLike`, *optional*):

Can be either:

- A string, the *model id* (for example `google/ddpm-celebahq-256`) of a pretrained model hosted on

the Hub.

- A path to a *directory* (for example `./my_model_directory`) containing the model weights saved

with [`~ModelMixin.save_pretrained`].

cache_dir (`Union[str, os.PathLike]`, *optional*):

Path to a directory where a downloaded pretrained model configuration is cached if the standard cache

is not used.

torch_dtype (`str` or `torch.dtype`, *optional*):

Override the default `torch.dtype` and load the model with another dtype. If `"auto"` is passed, the

dtype is automatically derived from the model's weights.

force_download (`bool`, *optional*, defaults to `False`):

Whether or not to force the (re-)download of the model weights and configuration files, overriding the

cached versions if they exist.

resume_download:

Deprecated and ignored. All downloads are now resumed by default when possible. Will be removed in v1

of Diffusers.

proxies (`Dict[str, str]`, *optional*):

A dictionary of proxy servers to use by protocol or endpoint, for example, `{'http': 'foo.bar:3128',

'http://hostname': 'foo.bar:4012'}`. The proxies are used on each request.

output_loading_info (`bool`, *optional*, defaults to `False`):

Whether or not to also return a dictionary containing missing keys, unexpected keys and error messages.

local_files_only(`bool`, *optional*, defaults to `False`):

Whether to only load local model weights and configuration files or not. If set to `True`, the model

won't be downloaded from the Hub.

token (`str` or *bool*, *optional*):

The token to use as HTTP bearer authorization for remote files. If `True`, the token generated from

`diffusers-cli login` (stored in `~/.huggingface`) is used.

revision (`str`, *optional*, defaults to `"main"`):

The specific model version to use. It can be a branch name, a tag name, a commit id, or any identifier

allowed by Git.

from_flax (`bool`, *optional*, defaults to `False`):

Load the model weights from a Flax checkpoint save file.

subfolder (`str`, *optional*, defaults to `""`):

The subfolder location of a model file within a larger model repository on the Hub or locally.

mirror (`str`, *optional*):

Mirror source to resolve accessibility issues if you're downloading a model in China. We do not

guarantee the timeliness or safety of the source, and you should refer to the mirror site for more

information.

device_map (`str` or `Dict[str, Union[int, str, torch.device]]`, *optional*):

A map that specifies where each submodule should go. It doesn't need to be defined for each

parameter/buffer name; once a given module name is inside, every submodule of it will be sent to the

same device.

Set `device_map="auto"` to have 🤗 Accelerate automatically compute the most optimized `device_map`. For

more information about each option see [designing a device

map](https://hf.co/docs/accelerate/main/en/usage_guides/big_modeling#designing-a-device-map).

max_memory (`Dict`, *optional*):

A dictionary device identifier for the maximum memory. Will default to the maximum memory available for

each GPU and the available CPU RAM if unset.

offload_folder (`str` or `os.PathLike`, *optional*):

The path to offload weights if `device_map` contains the value `"disk"`.

offload_state_dict (`bool`, *optional*):

If `True`, temporarily offloads the CPU state dict to the hard drive to avoid running out of CPU RAM if

the weight of the CPU state dict + the biggest shard of the checkpoint does not fit. Defaults to `True`

when there is some disk offload.

low_cpu_mem_usage (`bool`, *optional*, defaults to `True` if torch version >= 1.9.0 else `False`):

Speed up model loading only loading the pretrained weights and not initializing the weights. This also

tries to not use more than 1x model size in CPU memory (including peak memory) while loading the model.

Only supported for PyTorch >= 1.9.0. If you are using an older version of PyTorch, setting this

argument to `True` will raise an error.

variant (`str`, *optional*):

Load weights from a specified `variant` filename such as `"fp16"` or `"ema"`. This is ignored when

loading `from_flax`.

use_safetensors (`bool`, *optional*, defaults to `None`):

If set to `None`, the `safetensors` weights are downloaded if they're available **and** if the

`safetensors` library is installed. If set to `True`, the model is forcibly loaded from `safetensors`

weights. If set to `False`, `safetensors` weights are not loaded.

<Tip>

To use private or [gated models](https://huggingface.co/docs/hub/models-gated#gated-models), log-in with

`huggingface-cli login`. You can also activate the special

["offline-mode"](https://huggingface.co/diffusers/installation.html#offline-mode) to use this method in a

firewalled environment.

</Tip>

Example:

```py

from diffusers import UNet2DConditionModel

unet = UNet2DConditionModel.from_pretrained("runwayml/stable-diffusion-v1-5", subfolder="unet")

```

If you get the error message below, you need to finetune the weights for your downstream task:

```bash

Some weights of UNet2DConditionModel were not initialized from the model checkpoint at runwayml/stable-diffusion-v1-5 and are newly initialized because the shapes did not match:

- conv_in.weight: found shape torch.Size([320, 4, 3, 3]) in the checkpoint and torch.Size([320, 9, 3, 3]) in the model instantiated

You should probably TRAIN this model on a down-stream task to be able to use it for predictions and inference.

```

"""

cache_dir = kwargs.pop("cache_dir", None)

ignore_mismatched_sizes = kwargs.pop("ignore_mismatched_sizes", False)

force_download = kwargs.pop("force_download", False)

from_flax = kwargs.pop("from_flax", False)

resume_download = kwargs.pop("resume_download", None)

proxies = kwargs.pop("proxies", None)

output_loading_info = kwargs.pop("output_loading_info", False)

local_files_only = kwargs.pop("local_files_only", None)

token = kwargs.pop("token", None)

revision = kwargs.pop("revision", None)

torch_dtype = kwargs.pop("torch_dtype", None)

subfolder = kwargs.pop("subfolder", None)

device_map = kwargs.pop("device_map", None)

max_memory = kwargs.pop("max_memory", None)

offload_folder = kwargs.pop("offload_folder", None)

offload_state_dict = kwargs.pop("offload_state_dict", False)

low_cpu_mem_usage = kwargs.pop("low_cpu_mem_usage", _LOW_CPU_MEM_USAGE_DEFAULT)

variant = kwargs.pop("variant", None)

use_safetensors = kwargs.pop("use_safetensors", None)

allow_pickle = False

if use_safetensors is None:

use_safetensors = True

allow_pickle = True

if low_cpu_mem_usage and not is_accelerate_available():

low_cpu_mem_usage = False

logger.warning(

"Cannot initialize model with low cpu memory usage because `accelerate` was not found in the"

" environment. Defaulting to `low_cpu_mem_usage=False`. It is strongly recommended to install"

" `accelerate` for faster and less memory-intense model loading. You can do so with: \n```\npip"

" install accelerate\n```\n."

)

if device_map is not None and not is_accelerate_available():

raise NotImplementedError(

"Loading and dispatching requires `accelerate`. Please make sure to install accelerate or set"

" `device_map=None`. You can install accelerate with `pip install accelerate`."

)

# Check if we can handle device_map and dispatching the weights

if device_map is not None and not is_torch_version(">=", "1.9.0"):

raise NotImplementedError(

"Loading and dispatching requires torch >= 1.9.0. Please either update your PyTorch version or set"

" `device_map=None`."

)

if low_cpu_mem_usage is True and not is_torch_version(">=", "1.9.0"):

raise NotImplementedError(

"Low memory initialization requires torch >= 1.9.0. Please either update your PyTorch version or set"

" `low_cpu_mem_usage=False`."

)

if low_cpu_mem_usage is False and device_map is not None:

raise ValueError(

f"You cannot set `low_cpu_mem_usage` to `False` while using device_map={device_map} for loading and"

" dispatching. Please make sure to set `low_cpu_mem_usage=True`."

)

# change device_map into a map if we passed an int, a str or a torch.device

if isinstance(device_map, torch.device):

device_map = {"": device_map}

elif isinstance(device_map, str) and device_map not in ["auto", "balanced", "balanced_low_0", "sequential"]:

try:

device_map = {"": torch.device(device_map)}

except RuntimeError:

raise ValueError(

"When passing device_map as a string, the value needs to be a device name (e.g. cpu, cuda:0) or "

f"'auto', 'balanced', 'balanced_low_0', 'sequential' but found {device_map}."

)

elif isinstance(device_map, int):

if device_map < 0:

raise ValueError(

"You can't pass device_map as a negative int. If you want to put the model on the cpu, pass device_map = 'cpu' "

)

else:

device_map = {"": device_map}

if device_map is not None:

if low_cpu_mem_usage is None:

low_cpu_mem_usage = True

elif not low_cpu_mem_usage:

raise ValueError("Passing along a `device_map` requires `low_cpu_mem_usage=True`")

if low_cpu_mem_usage:

if device_map is not None and not is_torch_version(">=", "1.10"):

# The max memory utils require PyTorch >= 1.10 to have torch.cuda.mem_get_info.

raise ValueError("`low_cpu_mem_usage` and `device_map` require PyTorch >= 1.10.")

# Load config if we don't provide a configuration

config_path = pretrained_model_name_or_path

user_agent = {

"diffusers": __version__,

"file_type": "model",

"framework": "pytorch",

}

# load config

config, unused_kwargs, commit_hash = cls.load_config(

config_path,

cache_dir=cache_dir,

return_unused_kwargs=True,

return_commit_hash=True,

force_download=force_download,

resume_download=resume_download,

proxies=proxies,

local_files_only=local_files_only,

token=token,

revision=revision,

subfolder=subfolder,

user_agent=user_agent,

**kwargs,

)

# load model

model_file = None

if from_flax:

model_file = _get_model_file(

pretrained_model_name_or_path,

weights_name=FLAX_WEIGHTS_NAME,

cache_dir=cache_dir,

force_download=force_download,

resume_download=resume_download,

proxies=proxies,

local_files_only=local_files_only,

token=token,

revision=revision,

subfolder=subfolder,

user_agent=user_agent,

commit_hash=commit_hash,

)

model = cls.from_config(config, **unused_kwargs)

# Convert the weights

from .modeling_pytorch_flax_utils import load_flax_checkpoint_in_pytorch_model

model = load_flax_checkpoint_in_pytorch_model(model, model_file)

else:

if use_safetensors:

try:

model_file = _get_model_file(

pretrained_model_name_or_path,

weights_name=_add_variant(SAFETENSORS_WEIGHTS_NAME, variant),

cache_dir=cache_dir,

force_download=force_download,

resume_download=resume_download,

proxies=proxies,

local_files_only=local_files_only,

token=token,

revision=revision,

subfolder=subfolder,

user_agent=user_agent,

commit_hash=commit_hash,

)

except IOError as e:

if not allow_pickle:

raise e

pass

if model_file is None:

model_file = _get_model_file(

pretrained_model_name_or_path,

weights_name=_add_variant(WEIGHTS_NAME, variant),

cache_dir=cache_dir,

force_download=force_download,

resume_download=resume_download,

proxies=proxies,

local_files_only=local_files_only,

token=token,

revision=revision,

subfolder=subfolder,

user_agent=user_agent,

commit_hash=commit_hash,

)

if low_cpu_mem_usage:

# Instantiate model with empty weights

with accelerate.init_empty_weights():

model = cls.from_config(config, **unused_kwargs)

# if device_map is None, load the state dict and move the params from meta device to the cpu

if device_map is None:

param_device = "cpu"

state_dict = load_state_dict(model_file, variant=variant)

model._convert_deprecated_attention_blocks(state_dict)

# move the params from meta device to cpu

missing_keys = set(model.state_dict().keys()) - set(state_dict.keys())

if len(missing_keys) > 0:

raise ValueError(

f"Cannot load {cls} from {pretrained_model_name_or_path} because the following keys are"

f" missing: \n {', '.join(missing_keys)}. \n Please make sure to pass"

" `low_cpu_mem_usage=False` and `device_map=None` if you want to randomly initialize"

" those weights or else make sure your checkpoint file is correct."

)

unexpected_keys = load_model_dict_into_meta(

model,

state_dict,

device=param_device,

dtype=torch_dtype,

model_name_or_path=pretrained_model_name_or_path,

)

if cls._keys_to_ignore_on_load_unexpected is not None:

for pat in cls._keys_to_ignore_on_load_unexpected:

unexpected_keys = [k for k in unexpected_keys if re.search(pat, k) is None]

if len(unexpected_keys) > 0:

logger.warning(

f"Some weights of the model checkpoint were not used when initializing {cls.__name__}: \n {[', '.join(unexpected_keys)]}"

)

else: # else let accelerate handle loading and dispatching.

# Load weights and dispatch according to the device_map

# by default the device_map is None and the weights are loaded on the CPU

device_map = _determine_device_map(model, device_map, max_memory, torch_dtype)

try:

accelerate.load_checkpoint_and_dispatch(

model,

model_file,

device_map,

max_memory=max_memory,

offload_folder=offload_folder,

offload_state_dict=offload_state_dict,

dtype=torch_dtype,

force_hooks=True,

strict=True,

)

except AttributeError as e:

# When using accelerate loading, we do not have the ability to load the state

# dict and rename the weight names manually. Additionally, accelerate skips

# torch loading conventions and directly writes into `module.{_buffers, _parameters}`

# (which look like they should be private variables?), so we can't use the standard hooks

# to rename parameters on load. We need to mimic the original weight names so the correct

# attributes are available. After we have loaded the weights, we convert the deprecated

# names to the new non-deprecated names. Then we _greatly encourage_ the user to convert

# the weights so we don't have to do this again.

if "'Attention' object has no attribute" in str(e):

logger.warning(

f"Taking `{str(e)}` while using `accelerate.load_checkpoint_and_dispatch` to mean {pretrained_model_name_or_path}"

" was saved with deprecated attention block weight names. We will load it with the deprecated attention block"

" names and convert them on the fly to the new attention block format. Please re-save the model after this conversion,"

" so we don't have to do the on the fly renaming in the future. If the model is from a hub checkpoint,"

" please also re-upload it or open a PR on the original repository."

)

model._temp_convert_self_to_deprecated_attention_blocks()

accelerate.load_checkpoint_and_dispatch(

model,

model_file,

device_map,

max_memory=max_memory,

offload_folder=offload_folder,

offload_state_dict=offload_state_dict,

dtype=torch_dtype,

)

model._undo_temp_convert_self_to_deprecated_attention_blocks()

else:

raise e

loading_info = {

"missing_keys": [],

"unexpected_keys": [],

"mismatched_keys": [],

"error_msgs": [],

}

else:

model = cls.from_config(config, **unused_kwargs)

state_dict = load_state_dict(model_file, variant=variant)

model._convert_deprecated_attention_blocks(state_dict)

model, missing_keys, unexpected_keys, mismatched_keys, error_msgs = cls._load_pretrained_model(

model,

state_dict,

model_file,

pretrained_model_name_or_path,

ignore_mismatched_sizes=ignore_mismatched_sizes,

)

loading_info = {

"missing_keys": missing_keys,

"unexpected_keys": unexpected_keys,

"mismatched_keys": mismatched_keys,

"error_msgs": error_msgs,

}

if torch_dtype is not None and not isinstance(torch_dtype, torch.dtype):

raise ValueError(

f"{torch_dtype} needs to be of type `torch.dtype`, e.g. `torch.float16`, but is {type(torch_dtype)}."

)

elif torch_dtype is not None:

model = model.to(torch_dtype)

model.register_to_config(_name_or_path=pretrained_model_name_or_path)

# Set model in evaluation mode to deactivate DropOut modules by default

model.eval()

if output_loading_info:

return model, loading_info

return model

@classmethod

def _load_pretrained_model(

cls,

model,

state_dict: OrderedDict,

resolved_archive_file,

pretrained_model_name_or_path: Union[str, os.PathLike],

ignore_mismatched_sizes: bool = False,

):

# Retrieve missing & unexpected_keys

model_state_dict = model.state_dict()

loaded_keys = list(state_dict.keys())

expected_keys = list(model_state_dict.keys())

original_loaded_keys = loaded_keys

missing_keys = list(set(expected_keys) - set(loaded_keys))

unexpected_keys = list(set(loaded_keys) - set(expected_keys))

# Make sure we are able to load base models as well as derived models (with heads)

model_to_load = model

def _find_mismatched_keys(

state_dict,

model_state_dict,

loaded_keys,

ignore_mismatched_sizes,

):

mismatched_keys = []

if ignore_mismatched_sizes:

for checkpoint_key in loaded_keys:

model_key = checkpoint_key

if (

model_key in model_state_dict

and state_dict[checkpoint_key].shape != model_state_dict[model_key].shape

):

mismatched_keys.append(

(checkpoint_key, state_dict[checkpoint_key].shape, model_state_dict[model_key].shape)

)

del state_dict[checkpoint_key]

return mismatched_keys

if state_dict is not None:

# Whole checkpoint

mismatched_keys = _find_mismatched_keys(

state_dict,

model_state_dict,

original_loaded_keys,

ignore_mismatched_sizes,

)

error_msgs = _load_state_dict_into_model(model_to_load, state_dict)

if len(error_msgs) > 0:

error_msg = "\n\t".join(error_msgs)

if "size mismatch" in error_msg:

error_msg += (

"\n\tYou may consider adding `ignore_mismatched_sizes=True` in the model `from_pretrained` method."

)

raise RuntimeError(f"Error(s) in loading state_dict for {model.__class__.__name__}:\n\t{error_msg}")

if len(unexpected_keys) > 0:

logger.warning(

f"Some weights of the model checkpoint at {pretrained_model_name_or_path} were not used when"

f" initializing {model.__class__.__name__}: {unexpected_keys}\n- This IS expected if you are"

f" initializing {model.__class__.__name__} from the checkpoint of a model trained on another task"

" or with another architecture (e.g. initializing a BertForSequenceClassification model from a"

" BertForPreTraining model).\n- This IS NOT expected if you are initializing"

f" {model.__class__.__name__} from the checkpoint of a model that you expect to be exactly"

" identical (initializing a BertForSequenceClassification model from a"

" BertForSequenceClassification model)."

)

else:

logger.info(f"All model checkpoint weights were used when initializing {model.__class__.__name__}.\n")

if len(missing_keys) > 0:

logger.warning(

f"Some weights of {model.__class__.__name__} were not initialized from the model checkpoint at"

f" {pretrained_model_name_or_path} and are newly initialized: {missing_keys}\nYou should probably"

" TRAIN this model on a down-stream task to be able to use it for predictions and inference."

)

elif len(mismatched_keys) == 0:

logger.info(

f"All the weights of {model.__class__.__name__} were initialized from the model checkpoint at"

f" {pretrained_model_name_or_path}.\nIf your task is similar to the task the model of the"

f" checkpoint was trained on, you can already use {model.__class__.__name__} for predictions"

" without further training."

)

if len(mismatched_keys) > 0:

mismatched_warning = "\n".join(

[

f"- {key}: found shape {shape1} in the checkpoint and {shape2} in the model instantiated"

for key, shape1, shape2 in mismatched_keys

]

)

logger.warning(

f"Some weights of {model.__class__.__name__} were not initialized from the model checkpoint at"

f" {pretrained_model_name_or_path} and are newly initialized because the shapes did not"

f" match:\n{mismatched_warning}\nYou should probably TRAIN this model on a down-stream task to be"

" able to use it for predictions and inference."

)

return model, missing_keys, unexpected_keys, mismatched_keys, error_msgs

# Adapted from `transformers` modeling_utils.py

def _get_no_split_modules(self, device_map: str):

"""

Get the modules of the model that should not be spit when using device_map. We iterate through the modules to

get the underlying `_no_split_modules`.

Args:

device_map (`str`):

The device map value. Options are ["auto", "balanced", "balanced_low_0", "sequential"]

Returns:

`List[str]`: List of modules that should not be split

"""

_no_split_modules = set()

modules_to_check = [self]

while len(modules_to_check) > 0:

module = modules_to_check.pop(-1)

# if the module does not appear in _no_split_modules, we also check the children

if module.__class__.__name__ not in _no_split_modules:

if isinstance(module, ModelMixin):

if module._no_split_modules is None:

raise ValueError(

f"{module.__class__.__name__} does not support `device_map='{device_map}'`. To implement support, the model "

"class needs to implement the `_no_split_modules` attribute."

)

else:

_no_split_modules = _no_split_modules | set(module._no_split_modules)

modules_to_check += list(module.children())

return list(_no_split_modules)

@property

def device(self) -> torch.device:

"""

`torch.device`: The device on which the module is (assuming that all the module parameters are on the same

device).