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from typing import Any, Dict, List, Optional, Union
import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F
from diffusers.configuration_utils import ConfigMixin, register_to_config
from diffusers.loaders import FromOriginalModelMixin, PeftAdapterMixin
from diffusers.models.attention import FeedForward
from diffusers.models.attention_processor import (
Attention,
FluxAttnProcessor2_0,
FluxSingleAttnProcessor2_0,
)
from diffusers.models.modeling_utils import ModelMixin
from diffusers.models.normalization import (
AdaLayerNormContinuous,
AdaLayerNormZero,
AdaLayerNormZeroSingle,
)
from diffusers.utils import (
USE_PEFT_BACKEND,
is_torch_version,
logging,
scale_lora_layers,
unscale_lora_layers,
)
from diffusers.utils.torch_utils import maybe_allow_in_graph
from diffusers.models.embeddings import (
CombinedTimestepGuidanceTextProjEmbeddings,
CombinedTimestepTextProjEmbeddings,
)
from diffusers.models.modeling_outputs import Transformer2DModelOutput
logger = logging.get_logger(__name__) # pylint: disable=invalid-name
# YiYi to-do: refactor rope related functions/classes
def rope(pos: torch.Tensor, dim: int, theta: int) -> torch.Tensor:
assert dim % 2 == 0, "The dimension must be even."
scale = torch.arange(0, dim, 2, dtype=torch.float64, device=pos.device) / dim
omega = 1.0 / (theta**scale)
batch_size, seq_length = pos.shape
out = torch.einsum("...n,d->...nd", pos, omega)
cos_out = torch.cos(out)
sin_out = torch.sin(out)
stacked_out = torch.stack([cos_out, -sin_out, sin_out, cos_out], dim=-1)
out = stacked_out.view(batch_size, -1, dim // 2, 2, 2)
return out.float()
# YiYi to-do: refactor rope related functions/classes
class EmbedND(nn.Module):
def __init__(self, dim: int, theta: int, axes_dim: List[int]):
super().__init__()
self.dim = dim
self.theta = theta
self.axes_dim = axes_dim
def forward(self, ids: torch.Tensor) -> torch.Tensor:
n_axes = ids.shape[-1]
emb = torch.cat(
[rope(ids[..., i], self.axes_dim[i], self.theta) for i in range(n_axes)],
dim=-3,
)
return emb.unsqueeze(1)
@maybe_allow_in_graph
class FluxSingleTransformerBlock(nn.Module):
r"""
A Transformer block following the MMDiT architecture, introduced in Stable Diffusion 3.
Reference: https://arxiv.org/abs/2403.03206
Parameters:
dim (`int`): The number of channels in the input and output.
num_attention_heads (`int`): The number of heads to use for multi-head attention.
attention_head_dim (`int`): The number of channels in each head.
context_pre_only (`bool`): Boolean to determine if we should add some blocks associated with the
processing of `context` conditions.
"""
def __init__(self, dim, num_attention_heads, attention_head_dim, mlp_ratio=4.0):
super().__init__()
self.mlp_hidden_dim = int(dim * mlp_ratio)
self.norm = AdaLayerNormZeroSingle(dim)
self.proj_mlp = nn.Linear(dim, self.mlp_hidden_dim)
self.act_mlp = nn.GELU(approximate="tanh")
self.proj_out = nn.Linear(dim + self.mlp_hidden_dim, dim)
processor = FluxSingleAttnProcessor2_0()
self.attn = Attention(
query_dim=dim,
cross_attention_dim=None,
dim_head=attention_head_dim,
heads=num_attention_heads,
out_dim=dim,
bias=True,
processor=processor,
qk_norm="rms_norm",
eps=1e-6,
pre_only=True,
)
def forward(
self,
hidden_states: torch.FloatTensor,
temb: torch.FloatTensor,
image_rotary_emb=None,
):
residual = hidden_states
norm_hidden_states, gate = self.norm(hidden_states, emb=temb)
mlp_hidden_states = self.act_mlp(self.proj_mlp(norm_hidden_states))
attn_output = self.attn(
hidden_states=norm_hidden_states,
image_rotary_emb=image_rotary_emb,
)
hidden_states = torch.cat([attn_output, mlp_hidden_states], dim=2)
gate = gate.unsqueeze(1)
hidden_states = gate * self.proj_out(hidden_states)
hidden_states = residual + hidden_states
if hidden_states.dtype == torch.float16:
hidden_states = hidden_states.clip(-65504, 65504)
return hidden_states
@maybe_allow_in_graph
class FluxTransformerBlock(nn.Module):
r"""
A Transformer block following the MMDiT architecture, introduced in Stable Diffusion 3.
Reference: https://arxiv.org/abs/2403.03206
Parameters:
dim (`int`): The number of channels in the input and output.
num_attention_heads (`int`): The number of heads to use for multi-head attention.
attention_head_dim (`int`): The number of channels in each head.
context_pre_only (`bool`): Boolean to determine if we should add some blocks associated with the
processing of `context` conditions.
"""
def __init__(
self, dim, num_attention_heads, attention_head_dim, qk_norm="rms_norm", eps=1e-6
):
super().__init__()
self.norm1 = AdaLayerNormZero(dim)
self.norm1_context = AdaLayerNormZero(dim)
if hasattr(F, "scaled_dot_product_attention"):
processor = FluxAttnProcessor2_0()
else:
raise ValueError(
"The current PyTorch version does not support the `scaled_dot_product_attention` function."
)
self.attn = Attention(
query_dim=dim,
cross_attention_dim=None,
added_kv_proj_dim=dim,
dim_head=attention_head_dim,
heads=num_attention_heads,
out_dim=dim,
context_pre_only=False,
bias=True,
processor=processor,
qk_norm=qk_norm,
eps=eps,
)
self.norm2 = nn.LayerNorm(dim, elementwise_affine=False, eps=1e-6)
self.ff = FeedForward(dim=dim, dim_out=dim, activation_fn="gelu-approximate")
self.norm2_context = nn.LayerNorm(dim, elementwise_affine=False, eps=1e-6)
self.ff_context = FeedForward(
dim=dim, dim_out=dim, activation_fn="gelu-approximate"
)
# let chunk size default to None
self._chunk_size = None
self._chunk_dim = 0
def forward(
self,
hidden_states: torch.FloatTensor,
encoder_hidden_states: torch.FloatTensor,
temb: torch.FloatTensor,
image_rotary_emb=None,
):
norm_hidden_states, gate_msa, shift_mlp, scale_mlp, gate_mlp = self.norm1(
hidden_states, emb=temb
)
(
norm_encoder_hidden_states,
c_gate_msa,
c_shift_mlp,
c_scale_mlp,
c_gate_mlp,
) = self.norm1_context(encoder_hidden_states, emb=temb)
# Attention.
attn_output, context_attn_output = self.attn(
hidden_states=norm_hidden_states,
encoder_hidden_states=norm_encoder_hidden_states,
image_rotary_emb=image_rotary_emb,
)
# Process attention outputs for the `hidden_states`.
attn_output = gate_msa.unsqueeze(1) * attn_output
hidden_states = hidden_states + attn_output
norm_hidden_states = self.norm2(hidden_states)
norm_hidden_states = (
norm_hidden_states * (1 + scale_mlp[:, None]) + shift_mlp[:, None]
)
ff_output = self.ff(norm_hidden_states)
ff_output = gate_mlp.unsqueeze(1) * ff_output
hidden_states = hidden_states + ff_output
# Process attention outputs for the `encoder_hidden_states`.
context_attn_output = c_gate_msa.unsqueeze(1) * context_attn_output
encoder_hidden_states = encoder_hidden_states + context_attn_output
norm_encoder_hidden_states = self.norm2_context(encoder_hidden_states)
norm_encoder_hidden_states = (
norm_encoder_hidden_states * (1 + c_scale_mlp[:, None])
+ c_shift_mlp[:, None]
)
context_ff_output = self.ff_context(norm_encoder_hidden_states)
encoder_hidden_states = (
encoder_hidden_states + c_gate_mlp.unsqueeze(1) * context_ff_output
)
if encoder_hidden_states.dtype == torch.float16:
encoder_hidden_states = encoder_hidden_states.clip(-65504, 65504)
return encoder_hidden_states, hidden_states
class FluxTransformer2DModel(
ModelMixin, ConfigMixin, PeftAdapterMixin, FromOriginalModelMixin
):
"""
The Transformer model introduced in Flux.
Reference: https://blackforestlabs.ai/announcing-black-forest-labs/
Parameters:
patch_size (`int`): Patch size to turn the input data into small patches.
in_channels (`int`, *optional*, defaults to 16): The number of channels in the input.
num_layers (`int`, *optional*, defaults to 18): The number of layers of MMDiT blocks to use.
num_single_layers (`int`, *optional*, defaults to 18): The number of layers of single DiT blocks to use.
attention_head_dim (`int`, *optional*, defaults to 64): The number of channels in each head.
num_attention_heads (`int`, *optional*, defaults to 18): The number of heads to use for multi-head attention.
joint_attention_dim (`int`, *optional*): The number of `encoder_hidden_states` dimensions to use.
pooled_projection_dim (`int`): Number of dimensions to use when projecting the `pooled_projections`.
guidance_embeds (`bool`, defaults to False): Whether to use guidance embeddings.
"""
_supports_gradient_checkpointing = True
@register_to_config
def __init__(
self,
patch_size: int = 1,
in_channels: int = 64,
num_layers: int = 19,
num_single_layers: int = 38,
attention_head_dim: int = 128,
num_attention_heads: int = 24,
joint_attention_dim: int = 4096,
pooled_projection_dim: int = 768,
guidance_embeds: bool = False,
axes_dims_rope: List[int] = [16, 56, 56],
):
super().__init__()
self.out_channels = in_channels
self.inner_dim = (
self.config.num_attention_heads * self.config.attention_head_dim
)
self.pos_embed = EmbedND(
dim=self.inner_dim, theta=10000, axes_dim=axes_dims_rope
)
text_time_guidance_cls = (
CombinedTimestepGuidanceTextProjEmbeddings
if guidance_embeds
else CombinedTimestepTextProjEmbeddings
)
self.time_text_embed = text_time_guidance_cls(
embedding_dim=self.inner_dim,
pooled_projection_dim=self.config.pooled_projection_dim,
)
self.context_embedder = nn.Linear(
self.config.joint_attention_dim, self.inner_dim
)
self.x_embedder = torch.nn.Linear(self.config.in_channels, self.inner_dim)
self.transformer_blocks = nn.ModuleList(
[
FluxTransformerBlock(
dim=self.inner_dim,
num_attention_heads=self.config.num_attention_heads,
attention_head_dim=self.config.attention_head_dim,
)
for i in range(self.config.num_layers)
]
)
self.single_transformer_blocks = nn.ModuleList(
[
FluxSingleTransformerBlock(
dim=self.inner_dim,
num_attention_heads=self.config.num_attention_heads,
attention_head_dim=self.config.attention_head_dim,
)
for i in range(self.config.num_single_layers)
]
)
self.norm_out = AdaLayerNormContinuous(
self.inner_dim, self.inner_dim, elementwise_affine=False, eps=1e-6
)
self.proj_out = nn.Linear(
self.inner_dim, patch_size * patch_size * self.out_channels, bias=True
)
self.gradient_checkpointing = False
def _set_gradient_checkpointing(self, module, value=False):
if hasattr(module, "gradient_checkpointing"):
module.gradient_checkpointing = value
def forward(
self,
hidden_states: torch.Tensor,
encoder_hidden_states: torch.Tensor = None,
pooled_projections: torch.Tensor = None,
timestep: torch.LongTensor = None,
img_ids: torch.Tensor = None,
txt_ids: torch.Tensor = None,
guidance: torch.Tensor = None,
joint_attention_kwargs: Optional[Dict[str, Any]] = None,
controlnet_block_samples=None,
controlnet_single_block_samples=None,
return_dict: bool = True,
) -> Union[torch.FloatTensor, Transformer2DModelOutput]:
"""
The [`FluxTransformer2DModel`] forward method.
Args:
hidden_states (`torch.FloatTensor` of shape `(batch size, channel, height, width)`):
Input `hidden_states`.
encoder_hidden_states (`torch.FloatTensor` of shape `(batch size, sequence_len, embed_dims)`):
Conditional embeddings (embeddings computed from the input conditions such as prompts) to use.
pooled_projections (`torch.FloatTensor` of shape `(batch_size, projection_dim)`): Embeddings projected
from the embeddings of input conditions.
timestep ( `torch.LongTensor`):
Used to indicate denoising step.
block_controlnet_hidden_states: (`list` of `torch.Tensor`):
A list of tensors that if specified are added to the residuals of transformer blocks.
joint_attention_kwargs (`dict`, *optional*):
A kwargs dictionary that if specified is passed along to the `AttentionProcessor` as defined under
`self.processor` in
[diffusers.models.attention_processor](https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/attention_processor.py).
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`~models.transformer_2d.Transformer2DModelOutput`] instead of a plain
tuple.
Returns:
If `return_dict` is True, an [`~models.transformer_2d.Transformer2DModelOutput`] is returned, otherwise a
`tuple` where the first element is the sample tensor.
"""
if joint_attention_kwargs is not None:
joint_attention_kwargs = joint_attention_kwargs.copy()
lora_scale = joint_attention_kwargs.pop("scale", 1.0)
else:
lora_scale = 1.0
if USE_PEFT_BACKEND:
# weight the lora layers by setting `lora_scale` for each PEFT layer
scale_lora_layers(self, lora_scale)
else:
if (
joint_attention_kwargs is not None
and joint_attention_kwargs.get("scale", None) is not None
):
logger.warning(
"Passing `scale` via `joint_attention_kwargs` when not using the PEFT backend is ineffective."
)
hidden_states = self.x_embedder(hidden_states)
timestep = timestep.to(hidden_states.dtype) * 1000
if guidance is not None:
guidance = guidance.to(hidden_states.dtype) * 1000
else:
guidance = None
temb = (
self.time_text_embed(timestep, pooled_projections)
if guidance is None
else self.time_text_embed(timestep, guidance, pooled_projections)
)
encoder_hidden_states = self.context_embedder(encoder_hidden_states)
txt_ids = txt_ids.expand(img_ids.size(0), -1, -1)
ids = torch.cat((txt_ids, img_ids), dim=1)
image_rotary_emb = self.pos_embed(ids)
for index_block, block in enumerate(self.transformer_blocks):
if self.training and self.gradient_checkpointing:
def create_custom_forward(module, return_dict=None):
def custom_forward(*inputs):
if return_dict is not None:
return module(*inputs, return_dict=return_dict)
else:
return module(*inputs)
return custom_forward
ckpt_kwargs: Dict[str, Any] = (
{"use_reentrant": False} if is_torch_version(">=", "1.11.0") else {}
)
(
encoder_hidden_states,
hidden_states,
) = torch.utils.checkpoint.checkpoint(
create_custom_forward(block),
hidden_states,
encoder_hidden_states,
temb,
image_rotary_emb,
**ckpt_kwargs,
)
else:
encoder_hidden_states, hidden_states = block(
hidden_states=hidden_states,
encoder_hidden_states=encoder_hidden_states,
temb=temb,
image_rotary_emb=image_rotary_emb,
)
# controlnet residual
if controlnet_block_samples is not None:
interval_control = len(self.transformer_blocks) / len(
controlnet_block_samples
)
interval_control = int(np.ceil(interval_control))
hidden_states = (
hidden_states
+ controlnet_block_samples[index_block // interval_control]
)
hidden_states = torch.cat([encoder_hidden_states, hidden_states], dim=1)
for index_block, block in enumerate(self.single_transformer_blocks):
if self.training and self.gradient_checkpointing:
def create_custom_forward(module, return_dict=None):
def custom_forward(*inputs):
if return_dict is not None:
return module(*inputs, return_dict=return_dict)
else:
return module(*inputs)
return custom_forward
ckpt_kwargs: Dict[str, Any] = (
{"use_reentrant": False} if is_torch_version(">=", "1.11.0") else {}
)
hidden_states = torch.utils.checkpoint.checkpoint(
create_custom_forward(block),
hidden_states,
temb,
image_rotary_emb,
**ckpt_kwargs,
)
else:
hidden_states = block(
hidden_states=hidden_states,
temb=temb,
image_rotary_emb=image_rotary_emb,
)
# controlnet residual
if controlnet_single_block_samples is not None:
interval_control = len(self.single_transformer_blocks) / len(
controlnet_single_block_samples
)
interval_control = int(np.ceil(interval_control))
hidden_states[:, encoder_hidden_states.shape[1] :, ...] = (
hidden_states[:, encoder_hidden_states.shape[1] :, ...]
+ controlnet_single_block_samples[index_block // interval_control]
)
hidden_states = hidden_states[:, encoder_hidden_states.shape[1] :, ...]
hidden_states = self.norm_out(hidden_states, temb)
output = self.proj_out(hidden_states)
if USE_PEFT_BACKEND:
# remove `lora_scale` from each PEFT layer
unscale_lora_layers(self, lora_scale)
if not return_dict:
return (output,)
return Transformer2DModelOutput(sample=output)
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