RotEx / flux /modules /adaptive_blocks.py
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"""
Adaptive Flux Blocks with enhanced AdaLN integration.
These blocks serve as building blocks for the SwiftFlux architecture with
advanced style transfer control and optional MoE-compatible components.
Author: https://github.com/datnguyen-tien204
"""
import torch
from torch import nn
from einops import rearrange
from flux.modules.normalization import AdaLNModulation
from flux.utils.math import attention, apply_rope
from flux.utils.logger_utils import ConsoleLogger
# Constants
SWIGLU_HIDDEN_RATIO = 2 / 3 # Hidden dimension ratio for SwiGLU
class QKNorm(nn.Module):
"""Query-Key normalization for stable attention"""
def __init__(self, dim: int):
super().__init__()
self.query_norm = nn.LayerNorm(dim, elementwise_affine=True, eps=1e-6)
self.key_norm = nn.LayerNorm(dim, elementwise_affine=True, eps=1e-6)
def forward(self, q: torch.Tensor, k: torch.Tensor) -> tuple[torch.Tensor, torch.Tensor]:
return self.query_norm(q), self.key_norm(k)
class SwiGLU(nn.Module):
"""SwiGLU activation for efficient FFN"""
def __init__(self, in_features, hidden_features=None, out_features=None):
super().__init__()
out_features = out_features or in_features
hidden_features = hidden_features or in_features
hidden_features = int(hidden_features * SWIGLU_HIDDEN_RATIO)
self.w1 = nn.Linear(in_features, hidden_features)
self.w2 = nn.Linear(in_features, hidden_features)
self.w3 = nn.Linear(hidden_features, out_features)
self.silu = nn.SiLU()
def forward(self, x):
x1 = self.w1(x)
x2 = self.w2(x)
hidden = self.silu(x1) * x2
return self.w3(hidden)
class AdaptiveFluxBlock(nn.Module):
"""
Base Adaptive Flux Block with AdaLN integration.
Serves as foundation for both double-stream and single-stream variants.
Features:
- AdaLN for layer-wise style and conditioning control
- QKNorm for attention stability
- SwiGLU for efficient feed-forward
- Optional sparse activation support for MoE compatibility
"""
def __init__(self, hidden_size, num_heads, mlp_ratio=4.0, use_sparse=False):
super().__init__()
self.hidden_size = hidden_size
self.num_heads = num_heads
self.head_dim = hidden_size // num_heads
self.use_sparse = use_sparse
# Note: adaLN should be initialized in subclasses
def apply_adaptive_norm(self, x, scale, shift):
"""Apply AdaLN normalization with scale and shift"""
return x * (1 + scale.unsqueeze(1)) + shift.unsqueeze(1)
class AdaptiveDoubleStreamBlock(AdaptiveFluxBlock):
"""
Adaptive Double-Stream Block with enhanced AdaLN.
Processes image and style streams separately with cross-attention.
Improvements:
- Dedicated AdaLN for both streams
- Enhanced normalization for better style consistency
- Support for sparse activation patterns
"""
def __init__(self, hidden_size, num_heads, mlp_ratio=4.0, use_sparse=False):
super().__init__(hidden_size, num_heads, mlp_ratio, use_sparse)
# Image stream components
self.img_norm1 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
self.img_qkv = nn.Linear(hidden_size, hidden_size * 3)
self.img_proj = nn.Linear(hidden_size, hidden_size)
self.img_qk_norm = QKNorm(self.head_dim)
self.img_norm2 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
self.img_mlp = SwiGLU(hidden_size, int(hidden_size * mlp_ratio))
# Style stream components
self.sty_norm1 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
self.sty_qkv = nn.Linear(hidden_size, hidden_size * 3)
self.sty_proj = nn.Linear(hidden_size, hidden_size)
self.sty_qk_norm = QKNorm(self.head_dim)
self.sty_norm2 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
self.sty_mlp = SwiGLU(hidden_size, int(hidden_size * mlp_ratio))
# AdaLN with 12 components (6 for img, 6 for style)
self.adaLN = AdaLNModulation(hidden_size, components=12)
def forward(self, img, sty, vec, pe):
"""
Forward pass with dual-stream processing
Args:
img: Image features [B, L_img, D]
sty: Style features [B, L_sty, D]
vec: Conditioning vector [B, D]
pe: Position embeddings
Returns:
Updated (img, sty) features
"""
# Generate all modulation parameters
params = self.adaLN(vec)
(shift_i_a, scale_i_a, gate_i_a, shift_i_m, scale_i_m, gate_i_m,
shift_s_a, scale_s_a, gate_s_a, shift_s_m, scale_s_m, gate_s_m) = params
# Image stream - attention
img_mod = self.apply_adaptive_norm(self.img_norm1(img), scale_i_a, shift_i_a)
sty_mod = self.apply_adaptive_norm(self.sty_norm1(sty), scale_s_a, shift_s_a)
qkv_i = self.img_qkv(img_mod)
qkv_s = self.sty_qkv(sty_mod)
q_i, k_i, v_i = rearrange(qkv_i, "B L (K H D) -> K B L H D", K=3, H=self.num_heads)
q_s, k_s, v_s = rearrange(qkv_s, "B L (K H D) -> K B L H D", K=3, H=self.num_heads)
q_i, k_i = self.img_qk_norm(q_i, k_i)
q_s, k_s = self.sty_qk_norm(q_s, k_s)
# Preserve dtype for Flash Attention
dtype = img.dtype
q_i, k_i, v_i = q_i.to(dtype), k_i.to(dtype), v_i.to(dtype)
q_s, k_s, v_s = q_s.to(dtype), k_s.to(dtype), v_s.to(dtype)
# Apply RoPE if position embeddings provided
if pe is not None:
pe = pe.transpose(1, 2)
pe_s = pe[:, :1, ...]
pe_i = pe[:, 1:, ...]
q_i, k_i = apply_rope(q_i, k_i, pe_i)
q_s, k_s = apply_rope(q_s, k_s, pe_s)
q_i, k_i = q_i.to(dtype), k_i.to(dtype)
q_s, k_s = q_s.to(dtype), k_s.to(dtype)
# Cross-attention between streams
full_k = torch.cat([k_s, k_i], dim=1)
full_v = torch.cat([v_s, v_i], dim=1)
img_attn_out = self.img_proj(attention(q_i, full_k, full_v))
sty_attn_out = self.sty_proj(attention(q_s, full_k, full_v))
# Apply gating and residual
img = img + gate_i_a.unsqueeze(1) * img_attn_out
sty = sty + gate_s_a.unsqueeze(1) * sty_attn_out
# MLP blocks with AdaLN
img_mod = self.apply_adaptive_norm(self.img_norm2(img), scale_i_m, shift_i_m)
img = img + gate_i_m.unsqueeze(1) * self.img_mlp(img_mod)
sty_mod = self.apply_adaptive_norm(self.sty_norm2(sty), scale_s_m, shift_s_m)
sty = sty + gate_s_m.unsqueeze(1) * self.sty_mlp(sty_mod)
return img, sty
class AdaptiveSingleStreamBlock(AdaptiveFluxBlock):
"""
Adaptive Single-Stream Block with enhanced AdaLN.
Processes unified features with self-attention.
Improvements:
- Enhanced AdaLN control for unified stream
- Better style propagation through the network
- Optional sparse activation for MoE
"""
def __init__(self, hidden_size, num_heads, mlp_ratio=4.0, use_sparse=False):
super().__init__(hidden_size, num_heads, mlp_ratio, use_sparse)
self.norm1 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
self.qkv = nn.Linear(hidden_size, hidden_size * 3)
self.proj = nn.Linear(hidden_size, hidden_size)
self.qk_norm = QKNorm(self.head_dim)
self.norm2 = nn.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6)
self.mlp = SwiGLU(hidden_size, int(hidden_size * mlp_ratio))
# AdaLN with 6 components (scale, shift, gate for attention and MLP)
self.adaLN = AdaLNModulation(hidden_size, components=6)
def forward(self, x, vec, pe):
"""
Forward pass with single-stream processing
Args:
x: Input features [B, L, D]
vec: Conditioning vector [B, D]
pe: Position embeddings
Returns:
Updated features
"""
shift_a, scale_a, gate_a, shift_m, scale_m, gate_m = self.adaLN(vec)
# Attention with AdaLN
x_mod = self.apply_adaptive_norm(self.norm1(x), scale_a, shift_a)
qkv = self.qkv(x_mod)
q, k, v = rearrange(qkv, "B L (K H D) -> K B L H D", K=3, H=self.num_heads)
q, k = self.qk_norm(q, k)
dtype = x.dtype
q, k, v = q.to(dtype), k.to(dtype), v.to(dtype)
# Apply RoPE if position embeddings provided
if pe is not None:
pe_reshaped = pe.transpose(1, 2)
q, k = apply_rope(q, k, pe_reshaped)
q, k = q.to(dtype), k.to(dtype)
x_attn = self.proj(attention(q, k, v))
x = x + gate_a.unsqueeze(1) * x_attn
# MLP with AdaLN
x_mod = self.apply_adaptive_norm(self.norm2(x), scale_m, shift_m)
x = x + gate_m.unsqueeze(1) * self.mlp(x_mod)
return x
# For backward compatibility, create aliases
SwiftDoubleStreamBlock = AdaptiveDoubleStreamBlock
SwiftSingleStreamBlock = AdaptiveSingleStreamBlock
__all__ = [
'AdaptiveFluxBlock',
'AdaptiveDoubleStreamBlock',
'AdaptiveSingleStreamBlock',
'SwiftDoubleStreamBlock',
'SwiftSingleStreamBlock',
'QKNorm',
'SwiGLU',
]