257 lines
11 KiB
Python
257 lines
11 KiB
Python
import math
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from dataclasses import dataclass
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import torch
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from einops import rearrange
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from torch import Tensor, nn
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from .math import attention, rope
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import comfy.ops
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class EmbedND(nn.Module):
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def __init__(self, dim: int, theta: int, axes_dim: list):
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super().__init__()
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self.dim = dim
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self.theta = theta
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self.axes_dim = axes_dim
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def forward(self, ids: Tensor) -> Tensor:
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n_axes = ids.shape[-1]
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emb = torch.cat(
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[rope(ids[..., i], self.axes_dim[i], self.theta) for i in range(n_axes)],
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dim=-3,
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)
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return emb.unsqueeze(1)
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def timestep_embedding(t: Tensor, dim, max_period=10000, time_factor: float = 1000.0):
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"""
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Create sinusoidal timestep embeddings.
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:param t: a 1-D Tensor of N indices, one per batch element.
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These may be fractional.
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:param dim: the dimension of the output.
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:param max_period: controls the minimum frequency of the embeddings.
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:return: an (N, D) Tensor of positional embeddings.
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"""
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t = time_factor * t
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half = dim // 2
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freqs = torch.exp(-math.log(max_period) * torch.arange(start=0, end=half, dtype=torch.float32) / half).to(
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t.device
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)
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args = t[:, None].float() * freqs[None]
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embedding = torch.cat([torch.cos(args), torch.sin(args)], dim=-1)
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if dim % 2:
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embedding = torch.cat([embedding, torch.zeros_like(embedding[:, :1])], dim=-1)
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if torch.is_floating_point(t):
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embedding = embedding.to(t)
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return embedding
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class MLPEmbedder(nn.Module):
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def __init__(self, in_dim: int, hidden_dim: int, dtype=None, device=None, operations=None):
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super().__init__()
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self.in_layer = operations.Linear(in_dim, hidden_dim, bias=True, dtype=dtype, device=device)
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self.silu = nn.SiLU()
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self.out_layer = operations.Linear(hidden_dim, hidden_dim, bias=True, dtype=dtype, device=device)
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def forward(self, x: Tensor) -> Tensor:
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return self.out_layer(self.silu(self.in_layer(x)))
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class RMSNorm(torch.nn.Module):
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def __init__(self, dim: int, dtype=None, device=None, operations=None):
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super().__init__()
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self.scale = nn.Parameter(torch.empty((dim), dtype=dtype, device=device))
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def forward(self, x: Tensor):
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x_dtype = x.dtype
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x = x.float()
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rrms = torch.rsqrt(torch.mean(x**2, dim=-1, keepdim=True) + 1e-6)
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return (x * rrms).to(dtype=x_dtype) * comfy.ops.cast_to(self.scale, dtype=x_dtype, device=x.device)
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class QKNorm(torch.nn.Module):
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def __init__(self, dim: int, dtype=None, device=None, operations=None):
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super().__init__()
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self.query_norm = RMSNorm(dim, dtype=dtype, device=device, operations=operations)
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self.key_norm = RMSNorm(dim, dtype=dtype, device=device, operations=operations)
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def forward(self, q: Tensor, k: Tensor, v: Tensor) -> tuple:
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q = self.query_norm(q)
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k = self.key_norm(k)
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return q.to(v), k.to(v)
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class SelfAttention(nn.Module):
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def __init__(self, dim: int, num_heads: int = 8, qkv_bias: bool = False, dtype=None, device=None, operations=None):
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super().__init__()
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self.num_heads = num_heads
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head_dim = dim // num_heads
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self.qkv = operations.Linear(dim, dim * 3, bias=qkv_bias, dtype=dtype, device=device)
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self.norm = QKNorm(head_dim, dtype=dtype, device=device, operations=operations)
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self.proj = operations.Linear(dim, dim, dtype=dtype, device=device)
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def forward(self, x: Tensor, pe: Tensor) -> Tensor:
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qkv = self.qkv(x)
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q, k, v = rearrange(qkv, "B L (K H D) -> K B H L D", K=3, H=self.num_heads)
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q, k = self.norm(q, k, v)
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x = attention(q, k, v, pe=pe)
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x = self.proj(x)
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return x
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@dataclass
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class ModulationOut:
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shift: Tensor
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scale: Tensor
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gate: Tensor
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class Modulation(nn.Module):
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def __init__(self, dim: int, double: bool, dtype=None, device=None, operations=None):
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super().__init__()
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self.is_double = double
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self.multiplier = 6 if double else 3
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self.lin = operations.Linear(dim, self.multiplier * dim, bias=True, dtype=dtype, device=device)
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def forward(self, vec: Tensor) -> tuple:
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out = self.lin(nn.functional.silu(vec))[:, None, :].chunk(self.multiplier, dim=-1)
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return (
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ModulationOut(*out[:3]),
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ModulationOut(*out[3:]) if self.is_double else None,
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)
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class DoubleStreamBlock(nn.Module):
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def __init__(self, hidden_size: int, num_heads: int, mlp_ratio: float, qkv_bias: bool = False, dtype=None, device=None, operations=None):
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super().__init__()
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mlp_hidden_dim = int(hidden_size * mlp_ratio)
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self.num_heads = num_heads
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self.hidden_size = hidden_size
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self.img_mod = Modulation(hidden_size, double=True, dtype=dtype, device=device, operations=operations)
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self.img_norm1 = operations.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6, dtype=dtype, device=device)
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self.img_attn = SelfAttention(dim=hidden_size, num_heads=num_heads, qkv_bias=qkv_bias, dtype=dtype, device=device, operations=operations)
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self.img_norm2 = operations.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6, dtype=dtype, device=device)
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self.img_mlp = nn.Sequential(
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operations.Linear(hidden_size, mlp_hidden_dim, bias=True, dtype=dtype, device=device),
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nn.GELU(approximate="tanh"),
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operations.Linear(mlp_hidden_dim, hidden_size, bias=True, dtype=dtype, device=device),
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)
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self.txt_mod = Modulation(hidden_size, double=True, dtype=dtype, device=device, operations=operations)
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self.txt_norm1 = operations.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6, dtype=dtype, device=device)
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self.txt_attn = SelfAttention(dim=hidden_size, num_heads=num_heads, qkv_bias=qkv_bias, dtype=dtype, device=device, operations=operations)
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self.txt_norm2 = operations.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6, dtype=dtype, device=device)
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self.txt_mlp = nn.Sequential(
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operations.Linear(hidden_size, mlp_hidden_dim, bias=True, dtype=dtype, device=device),
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nn.GELU(approximate="tanh"),
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operations.Linear(mlp_hidden_dim, hidden_size, bias=True, dtype=dtype, device=device),
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)
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def forward(self, img: Tensor, txt: Tensor, vec: Tensor, pe: Tensor):
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img_mod1, img_mod2 = self.img_mod(vec)
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txt_mod1, txt_mod2 = self.txt_mod(vec)
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# prepare image for attention
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img_modulated = self.img_norm1(img)
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img_modulated = (1 + img_mod1.scale) * img_modulated + img_mod1.shift
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img_qkv = self.img_attn.qkv(img_modulated)
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img_q, img_k, img_v = rearrange(img_qkv, "B L (K H D) -> K B H L D", K=3, H=self.num_heads)
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img_q, img_k = self.img_attn.norm(img_q, img_k, img_v)
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# prepare txt for attention
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txt_modulated = self.txt_norm1(txt)
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txt_modulated = (1 + txt_mod1.scale) * txt_modulated + txt_mod1.shift
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txt_qkv = self.txt_attn.qkv(txt_modulated)
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txt_q, txt_k, txt_v = rearrange(txt_qkv, "B L (K H D) -> K B H L D", K=3, H=self.num_heads)
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txt_q, txt_k = self.txt_attn.norm(txt_q, txt_k, txt_v)
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# run actual attention
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q = torch.cat((txt_q, img_q), dim=2)
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k = torch.cat((txt_k, img_k), dim=2)
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v = torch.cat((txt_v, img_v), dim=2)
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attn = attention(q, k, v, pe=pe)
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txt_attn, img_attn = attn[:, : txt.shape[1]], attn[:, txt.shape[1] :]
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# calculate the img bloks
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img = img + img_mod1.gate * self.img_attn.proj(img_attn)
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img = img + img_mod2.gate * self.img_mlp((1 + img_mod2.scale) * self.img_norm2(img) + img_mod2.shift)
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# calculate the txt bloks
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txt = txt + txt_mod1.gate * self.txt_attn.proj(txt_attn)
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txt = txt + txt_mod2.gate * self.txt_mlp((1 + txt_mod2.scale) * self.txt_norm2(txt) + txt_mod2.shift)
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return img, txt
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class SingleStreamBlock(nn.Module):
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"""
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A DiT block with parallel linear layers as described in
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https://arxiv.org/abs/2302.05442 and adapted modulation interface.
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"""
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def __init__(
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self,
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hidden_size: int,
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num_heads: int,
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mlp_ratio: float = 4.0,
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qk_scale: float = None,
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dtype=None,
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device=None,
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operations=None
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):
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super().__init__()
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self.hidden_dim = hidden_size
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self.num_heads = num_heads
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head_dim = hidden_size // num_heads
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self.scale = qk_scale or head_dim**-0.5
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self.mlp_hidden_dim = int(hidden_size * mlp_ratio)
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# qkv and mlp_in
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self.linear1 = operations.Linear(hidden_size, hidden_size * 3 + self.mlp_hidden_dim, dtype=dtype, device=device)
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# proj and mlp_out
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self.linear2 = operations.Linear(hidden_size + self.mlp_hidden_dim, hidden_size, dtype=dtype, device=device)
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self.norm = QKNorm(head_dim, dtype=dtype, device=device, operations=operations)
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self.hidden_size = hidden_size
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self.pre_norm = operations.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6, dtype=dtype, device=device)
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self.mlp_act = nn.GELU(approximate="tanh")
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self.modulation = Modulation(hidden_size, double=False, dtype=dtype, device=device, operations=operations)
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def forward(self, x: Tensor, vec: Tensor, pe: Tensor) -> Tensor:
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mod, _ = self.modulation(vec)
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x_mod = (1 + mod.scale) * self.pre_norm(x) + mod.shift
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qkv, mlp = torch.split(self.linear1(x_mod), [3 * self.hidden_size, self.mlp_hidden_dim], dim=-1)
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q, k, v = rearrange(qkv, "B L (K H D) -> K B H L D", K=3, H=self.num_heads)
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q, k = self.norm(q, k, v)
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# compute attention
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attn = attention(q, k, v, pe=pe)
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# compute activation in mlp stream, cat again and run second linear layer
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output = self.linear2(torch.cat((attn, self.mlp_act(mlp)), 2))
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return x + mod.gate * output
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class LastLayer(nn.Module):
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def __init__(self, hidden_size: int, patch_size: int, out_channels: int, dtype=None, device=None, operations=None):
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super().__init__()
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self.norm_final = operations.LayerNorm(hidden_size, elementwise_affine=False, eps=1e-6, dtype=dtype, device=device)
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self.linear = operations.Linear(hidden_size, patch_size * patch_size * out_channels, bias=True, dtype=dtype, device=device)
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self.adaLN_modulation = nn.Sequential(nn.SiLU(), operations.Linear(hidden_size, 2 * hidden_size, bias=True, dtype=dtype, device=device))
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def forward(self, x: Tensor, vec: Tensor) -> Tensor:
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shift, scale = self.adaLN_modulation(vec).chunk(2, dim=1)
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x = (1 + scale[:, None, :]) * self.norm_final(x) + shift[:, None, :]
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x = self.linear(x)
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return x
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