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Python

# SPDX-License-Identifier: Apache-2.0
from typing import Any, Dict, List, Optional, Tuple, Union
import torch
import torch.nn as nn
import torch.nn.functional as F
from fastvideo.layers.mlp import MLP
from fastvideo.attention import LocalAttention
from fastvideo.configs.models.dits.glm_image import GlmImageDiTConfig
from fastvideo.layers.layernorm import ScaleResidualLayerNormScaleShift
from fastvideo.layers.linear import ReplicatedLinear
from fastvideo.layers.rotary_embedding import _apply_rotary_emb
from fastvideo.layers.visual_embedding import Timesteps
from fastvideo.models.dits.base import BaseDiT
from fastvideo.platforms import AttentionBackendEnum
class GlmImageLayerKVCache:
def __init__(self):
self.k_cache = None
self.v_cache = None
self.mode: Optional[str] = None
def store(self, k: torch.Tensor, v: torch.Tensor):
# Append along seq (dim=1).
if self.k_cache is None:
self.k_cache = k
self.v_cache = v
else:
self.k_cache = torch.cat([self.k_cache, k], dim=1)
self.v_cache = torch.cat([self.v_cache, v], dim=1)
def get(self):
return self.k_cache, self.v_cache
def clear(self):
self.k_cache = None
self.v_cache = None
self.mode = None
class GlmImageKVCache:
def __init__(self, num_layers: int):
self.num_layers = num_layers
self.caches = [GlmImageLayerKVCache() for _ in range(num_layers)]
def __getitem__(self, layer_idx: int) -> GlmImageLayerKVCache:
return self.caches[layer_idx]
def set_mode(self, mode: Optional[str]):
if mode is not None and mode not in ["write", "read", "skip"]:
raise ValueError(f"Invalid mode: {mode}, must be one of 'write', 'read', 'skip'")
for cache in self.caches:
cache.mode = mode
def clear(self):
for cache in self.caches:
cache.clear()
# =============================================================================
# Timestep and Text Projection
# =============================================================================
class GlmImageTimestepEmbedding(nn.Module):
def __init__(
self,
in_channels: int,
time_embed_dim: int,
act_fn: str = "silu",
out_dim: int = None,
):
super().__init__()
if out_dim is None:
out_dim = time_embed_dim
self.linear_1 = ReplicatedLinear(in_channels, time_embed_dim, bias=True)
if act_fn == "silu":
self.act = nn.SiLU()
elif act_fn == "gelu":
self.act = nn.GELU(approximate="tanh")
else:
self.act = nn.SiLU()
self.linear_2 = ReplicatedLinear(time_embed_dim, out_dim, bias=True)
def forward(self, sample: torch.Tensor) -> torch.Tensor:
sample, _ = self.linear_1(sample)
sample = self.act(sample)
sample, _ = self.linear_2(sample)
return sample
class GlmImageTextProjection(nn.Module):
def __init__(
self,
in_features: int,
hidden_size: int,
out_features: int = None,
act_fn: str = "silu",
):
super().__init__()
if out_features is None:
out_features = hidden_size
self.linear_1 = ReplicatedLinear(in_features, hidden_size, bias=True)
if act_fn == "silu":
self.act_1 = nn.SiLU()
elif act_fn == "gelu_tanh":
self.act_1 = nn.GELU(approximate="tanh")
else:
self.act_1 = nn.SiLU()
self.linear_2 = ReplicatedLinear(hidden_size, out_features, bias=True)
def forward(self, caption: torch.Tensor) -> torch.Tensor:
hidden_states, _ = self.linear_1(caption)
hidden_states = self.act_1(hidden_states)
hidden_states, _ = self.linear_2(hidden_states)
return hidden_states
class GlmImageCombinedTimestepSizeEmbeddings(nn.Module):
def __init__(
self,
embedding_dim: int,
condition_dim: int,
pooled_projection_dim: int,
timesteps_dim: int = 256,
):
super().__init__()
self.time_proj = Timesteps(num_channels=timesteps_dim, flip_sin_to_cos=True, downscale_freq_shift=0)
self.condition_proj = Timesteps(num_channels=condition_dim, flip_sin_to_cos=True, downscale_freq_shift=0)
self.timestep_embedder = GlmImageTimestepEmbedding(in_channels=timesteps_dim, time_embed_dim=embedding_dim)
self.condition_embedder = GlmImageTextProjection(pooled_projection_dim, embedding_dim, act_fn="silu")
def forward(
self,
timestep: torch.Tensor,
target_size: torch.Tensor,
crop_coords: torch.Tensor,
hidden_dtype: torch.dtype,
) -> torch.Tensor:
timesteps_proj = self.time_proj(timestep)
crop_coords_proj = self.condition_proj(crop_coords.flatten()).view(crop_coords.size(0), -1)
target_size_proj = self.condition_proj(target_size.flatten()).view(target_size.size(0), -1)
condition_proj = torch.cat([crop_coords_proj, target_size_proj], dim=1)
timesteps_emb = self.timestep_embedder(timesteps_proj.to(dtype=hidden_dtype))
condition_emb = self.condition_embedder(condition_proj.to(dtype=hidden_dtype))
conditioning = timesteps_emb + condition_emb
return conditioning
# =============================================================================
# Image Projector
# =============================================================================
class GlmImageImageProjector(nn.Module):
def __init__(
self,
in_channels: int = 16,
hidden_size: int = 2560,
patch_size: int = 2,
):
super().__init__()
self.patch_size = patch_size
self.proj = nn.Linear(in_channels * patch_size**2, hidden_size)
def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
batch_size, channel, height, width = hidden_states.shape
post_patch_height = height // self.patch_size
post_patch_width = width // self.patch_size
hidden_states = hidden_states.reshape(
batch_size,
channel,
post_patch_height,
self.patch_size,
post_patch_width,
self.patch_size,
)
hidden_states = (hidden_states.permute(0, 2, 4, 1, 3, 5).flatten(3, 5).flatten(1, 2))
hidden_states = self.proj(hidden_states)
return hidden_states
# =============================================================================
# AdaLayerNorm
# =============================================================================
class GlmImageAdaLayerNormZero(nn.Module):
def __init__(self, embedding_dim: int, dim: int) -> None:
super().__init__()
self.norm = nn.LayerNorm(dim, elementwise_affine=False, eps=1e-5)
self.norm_context = nn.LayerNorm(dim, elementwise_affine=False, eps=1e-5)
self.linear = ReplicatedLinear(embedding_dim, 12 * dim, bias=True)
def forward(
self,
hidden_states: torch.Tensor,
encoder_hidden_states: torch.Tensor,
temb: torch.Tensor,
) -> Tuple[torch.Tensor, ...]:
dtype = hidden_states.dtype
norm_hidden_states = self.norm(hidden_states).to(dtype=dtype)
norm_encoder_hidden_states = self.norm_context(encoder_hidden_states).to(dtype=dtype)
emb, _ = self.linear(temb)
(
shift_msa,
c_shift_msa,
scale_msa,
c_scale_msa,
gate_msa,
c_gate_msa,
shift_mlp,
c_shift_mlp,
scale_mlp,
c_scale_mlp,
gate_mlp,
c_gate_mlp,
) = emb.chunk(12, dim=1)
hidden_states = norm_hidden_states * (1 + scale_msa.unsqueeze(1)) + shift_msa.unsqueeze(1)
encoder_hidden_states = norm_encoder_hidden_states * (1 + c_scale_msa.unsqueeze(1)) + c_shift_msa.unsqueeze(1)
return (
hidden_states,
gate_msa,
shift_mlp,
scale_mlp,
gate_mlp,
encoder_hidden_states,
c_gate_msa,
c_shift_mlp,
c_scale_mlp,
c_gate_mlp,
)
# =============================================================================
# Attention
# =============================================================================
class GlmImageAttention(nn.Module):
def __init__(
self,
query_dim: int,
heads: int,
dim_head: int,
out_dim: int,
bias: bool = True,
qk_norm: str = "layer_norm",
elementwise_affine: bool = False,
eps: float = 1e-5,
supported_attention_backends: set[AttentionBackendEnum] | None = None,
prefix: str = "",
):
super().__init__()
self.heads = out_dim // dim_head if out_dim is not None else heads
self.num_kv_heads = self.heads
self.dim_head = dim_head
self.inner_dim = out_dim if out_dim is not None else dim_head * heads
self.inner_kv_dim = self.inner_dim
self.out_dim = out_dim if out_dim is not None else query_dim
self.to_q = ReplicatedLinear(query_dim, self.inner_dim, bias=bias)
self.to_k = ReplicatedLinear(query_dim, self.inner_kv_dim, bias=bias)
self.to_v = ReplicatedLinear(query_dim, self.inner_kv_dim, bias=bias)
self.to_out = nn.ModuleList([ReplicatedLinear(self.inner_dim, self.out_dim, bias=True)])
if qk_norm is None:
self.norm_q = None
self.norm_k = None
elif qk_norm == "layer_norm":
self.norm_q = nn.LayerNorm(dim_head, eps=eps, elementwise_affine=elementwise_affine)
self.norm_k = nn.LayerNorm(dim_head, eps=eps, elementwise_affine=elementwise_affine)
else:
raise ValueError(f"unknown qk_norm: {qk_norm}")
self.attn = LocalAttention(
num_heads=self.heads,
head_size=dim_head,
num_kv_heads=self.heads,
softmax_scale=None,
causal=False,
supported_attention_backends=supported_attention_backends,
)
def forward(
self,
hidden_states: torch.Tensor,
encoder_hidden_states: torch.Tensor,
image_rotary_emb: Optional[Tuple[torch.Tensor, torch.Tensor]] = None,
kv_cache: Optional[GlmImageLayerKVCache] = None,
) -> Tuple[torch.Tensor, torch.Tensor]:
dtype = encoder_hidden_states.dtype
batch_size, text_seq_length, embed_dim = encoder_hidden_states.shape
batch_size, image_seq_length, embed_dim = hidden_states.shape
hidden_states = torch.cat([encoder_hidden_states, hidden_states], dim=1)
# 1. QKV projections
query, _ = self.to_q(hidden_states)
key, _ = self.to_k(hidden_states)
value, _ = self.to_v(hidden_states)
query = query.unflatten(2, (self.heads, -1))
key = key.unflatten(2, (self.heads, -1))
value = value.unflatten(2, (self.heads, -1))
# 2. QK normalization
if self.norm_q is not None:
query = self.norm_q(query).to(dtype=dtype)
if self.norm_k is not None:
key = self.norm_k(key).to(dtype=dtype)
# 3. Rotational positional embeddings applied to latent stream
if image_rotary_emb is not None:
cos, sin = image_rotary_emb
query[:, text_seq_length:, :, :] = _apply_rotary_emb(query[:, text_seq_length:, :, :],
cos,
sin,
is_neox_style=True)
key[:, text_seq_length:, :, :] = _apply_rotary_emb(key[:, text_seq_length:, :, :],
cos,
sin,
is_neox_style=True)
# 4. KV Cache handling
if kv_cache is not None:
if kv_cache.mode == "write":
kv_cache.store(key, value)
elif kv_cache.mode == "read":
# Prepend cached condition k/v along seq (dim=1).
k_cache, v_cache = kv_cache.get()
key = torch.cat([k_cache, key], dim=1) if k_cache is not None else key
value = (torch.cat([v_cache, value], dim=1) if v_cache is not None else value)
elif kv_cache.mode == "skip":
pass
hidden_states = self.attn(query, key, value)
hidden_states = hidden_states.flatten(2, 3)
hidden_states = hidden_states.to(query.dtype)
# 6. Output projection
hidden_states, _ = self.to_out[0](hidden_states)
encoder_hidden_states, hidden_states = hidden_states.split(
[text_seq_length, hidden_states.size(1) - text_seq_length], dim=1)
return hidden_states, encoder_hidden_states
# =============================================================================
# Transformer Block
# =============================================================================
class GlmImageTransformerBlock(nn.Module):
def __init__(
self,
dim: int = 2560,
num_attention_heads: int = 64,
attention_head_dim: int = 40,
time_embed_dim: int = 512,
supported_attention_backends: set[AttentionBackendEnum] | None = None,
prefix: str = "",
) -> None:
super().__init__()
# 1. Attention
self.norm1 = GlmImageAdaLayerNormZero(time_embed_dim, dim)
self.attn1 = GlmImageAttention(
query_dim=dim,
heads=num_attention_heads,
dim_head=attention_head_dim,
out_dim=dim,
bias=True,
qk_norm="layer_norm",
elementwise_affine=False,
eps=1e-5,
supported_attention_backends=supported_attention_backends,
prefix=f"{prefix}.attn1",
)
# 2. Feedforward with fused ScaleResidualLayerNorm
self.norm2 = ScaleResidualLayerNormScaleShift(dim, norm_type="layer", eps=1e-5, elementwise_affine=False)
self.norm2_context = ScaleResidualLayerNormScaleShift(dim,
norm_type="layer",
eps=1e-5,
elementwise_affine=False)
self.ff = MLP(input_dim=dim, mlp_hidden_dim=dim * 4, output_dim=dim, act_type="gelu_pytorch_tanh")
def forward(
self,
hidden_states: torch.Tensor,
encoder_hidden_states: torch.Tensor,
temb: Optional[torch.Tensor] = None,
image_rotary_emb: Optional[Union[
Tuple[torch.Tensor, torch.Tensor],
List[Tuple[torch.Tensor, torch.Tensor]],
]] = None,
attention_kwargs: Optional[Dict[str, Any]] = None,
kv_cache: Optional[GlmImageLayerKVCache] = None,
) -> Tuple[torch.Tensor, torch.Tensor]:
# 1. Timestep conditioning
(
norm_hidden_states,
gate_msa,
shift_mlp,
scale_mlp,
gate_mlp,
norm_encoder_hidden_states,
c_gate_msa,
c_shift_mlp,
c_scale_mlp,
c_gate_mlp,
) = self.norm1(hidden_states, encoder_hidden_states, temb)
# 2. Attention
if attention_kwargs is None:
attention_kwargs = {}
attn_hidden_states, attn_encoder_hidden_states = self.attn1(
hidden_states=norm_hidden_states,
encoder_hidden_states=norm_encoder_hidden_states,
image_rotary_emb=image_rotary_emb,
kv_cache=kv_cache,
**attention_kwargs,
)
# 3. Feedforward (fused residual + norm + scale/shift)
norm_hidden_states, hidden_states = self.norm2(
hidden_states,
attn_hidden_states,
gate_msa.unsqueeze(1),
shift_mlp.unsqueeze(1),
scale_mlp.unsqueeze(1),
)
norm_encoder_hidden_states, encoder_hidden_states = self.norm2_context(
encoder_hidden_states,
attn_encoder_hidden_states,
c_gate_msa.unsqueeze(1),
c_shift_mlp.unsqueeze(1),
c_scale_mlp.unsqueeze(1),
)
ff_output = self.ff(norm_hidden_states)
ff_output_context = self.ff(norm_encoder_hidden_states)
hidden_states = hidden_states + ff_output * gate_mlp.unsqueeze(1)
encoder_hidden_states = (encoder_hidden_states + ff_output_context * c_gate_mlp.unsqueeze(1))
return hidden_states, encoder_hidden_states
# =============================================================================
# Rotary Positional Embedding
# =============================================================================
class GlmImageRotaryPosEmbed(nn.Module):
def __init__(self, dim: int, patch_size: int, theta: float = 10000.0) -> None:
super().__init__()
self.dim = dim
self.patch_size = patch_size
self.theta = theta
self._cache_key: tuple | None = None
self._cache_value: tuple[torch.Tensor, torch.Tensor] | None = None
def forward(self, hidden_states: torch.Tensor) -> Tuple[torch.Tensor, torch.Tensor]:
_, _, raw_h, raw_w = hidden_states.shape
height = raw_h // self.patch_size
width = raw_w // self.patch_size
device = hidden_states.device
cache_key = (height, width, device.type, device.index if device.index is not None else -1)
if self._cache_key == cache_key and self._cache_value is not None:
return self._cache_value
dim_h, dim_w = self.dim // 2, self.dim // 2
h_inv_freq = 1.0 / (self.theta
**(torch.arange(0, dim_h, 2, dtype=torch.float32, device=device)[:(dim_h // 2)] / dim_h))
w_inv_freq = 1.0 / (self.theta
**(torch.arange(0, dim_w, 2, dtype=torch.float32, device=device)[:(dim_w // 2)] / dim_w))
h_seq = torch.arange(height, device=device)
w_seq = torch.arange(width, device=device)
freqs_h = torch.outer(h_seq, h_inv_freq).unsqueeze(1).expand(height, width, -1)
freqs_w = torch.outer(w_seq, w_inv_freq).unsqueeze(0).expand(height, width, -1)
freqs = torch.cat([freqs_h, freqs_w], dim=-1).reshape(height * width, -1)
result = (freqs.cos(), freqs.sin())
self._cache_key = cache_key
self._cache_value = result
return result
# =============================================================================
# Final AdaLayerNorm
# =============================================================================
class GlmImageAdaLayerNormContinuous(nn.Module):
def __init__(
self,
embedding_dim: int,
conditioning_embedding_dim: int,
elementwise_affine: bool = True,
eps: float = 1e-5,
bias: bool = True,
norm_type: str = "layer_norm",
):
super().__init__()
self.linear = nn.Linear(conditioning_embedding_dim, embedding_dim * 2, bias=bias)
if norm_type == "layer_norm":
self.norm = nn.LayerNorm(embedding_dim, eps, elementwise_affine, bias)
elif norm_type == "rms_norm":
self.norm = nn.RMSNorm(embedding_dim, eps, elementwise_affine)
else:
raise ValueError(f"unknown norm_type {norm_type}")
def forward(self, x: torch.Tensor, conditioning_embedding: torch.Tensor) -> torch.Tensor:
emb = self.linear(conditioning_embedding.to(x.dtype))
scale, shift = torch.chunk(emb, 2, dim=1)
x = self.norm(x) * (1 + scale)[:, None, :] + shift[:, None, :]
return x
# =============================================================================
# Main Model
# =============================================================================
class GlmImageTransformer2DModel(BaseDiT):
_fsdp_shard_conditions = GlmImageDiTConfig().arch_config._fsdp_shard_conditions
_compile_conditions = GlmImageDiTConfig().arch_config._compile_conditions
_supported_attention_backends = (
AttentionBackendEnum.FLASH_ATTN,
AttentionBackendEnum.TORCH_SDPA,
)
param_names_mapping = GlmImageDiTConfig().arch_config.param_names_mapping
reverse_param_names_mapping = {}
lora_param_names_mapping = {}
def __init__(
self,
config: GlmImageDiTConfig,
hf_config: dict[str, Any],
):
super().__init__(config=config, hf_config=hf_config)
arch_config = config.arch_config
self.in_channels = arch_config.in_channels
self.out_channels = arch_config.out_channels
self.patch_size = arch_config.patch_size
self.num_layers = arch_config.num_layers
self.attention_head_dim = arch_config.attention_head_dim
self.num_attention_heads = arch_config.num_attention_heads
self.text_embed_dim = arch_config.text_embed_dim
self.time_embed_dim = arch_config.time_embed_dim
# GlmImage uses 2 additional SDXL-like conditions - target_size, crop_coords
# Each of these are sincos embeddings of shape 2 * condition_dim
pooled_projection_dim = 2 * 2 * arch_config.condition_dim
inner_dim = arch_config.num_attention_heads * arch_config.attention_head_dim
self.hidden_size = inner_dim
self.num_channels_latents = arch_config.out_channels
# 1. RoPE
self.rotary_emb = GlmImageRotaryPosEmbed(arch_config.attention_head_dim, arch_config.patch_size, theta=10000.0)
# 2. Patch & Text-timestep embedding
self.image_projector = GlmImageImageProjector(arch_config.in_channels, inner_dim, arch_config.patch_size)
self.glyph_projector = MLP(
input_dim=arch_config.text_embed_dim,
mlp_hidden_dim=inner_dim,
output_dim=inner_dim,
act_type="gelu",
)
self.prior_token_embedding = nn.Embedding(arch_config.prior_vq_quantizer_codebook_size, inner_dim)
self.prior_projector = MLP(
input_dim=inner_dim,
mlp_hidden_dim=inner_dim,
output_dim=inner_dim,
act_type="silu",
)
self.time_condition_embed = GlmImageCombinedTimestepSizeEmbeddings(
embedding_dim=arch_config.time_embed_dim,
condition_dim=arch_config.condition_dim,
pooled_projection_dim=pooled_projection_dim,
timesteps_dim=arch_config.time_embed_dim,
)
# 3. Transformer blocks
self.transformer_blocks = nn.ModuleList([
GlmImageTransformerBlock(
inner_dim,
arch_config.num_attention_heads,
arch_config.attention_head_dim,
arch_config.time_embed_dim,
supported_attention_backends=self._supported_attention_backends,
prefix=f"transformer_blocks.{i}",
) for i in range(arch_config.num_layers)
])
# 4. Output projection
self.norm_out = GlmImageAdaLayerNormContinuous(inner_dim, arch_config.time_embed_dim, elementwise_affine=False)
self.proj_out = nn.Linear(
inner_dim,
arch_config.patch_size * arch_config.patch_size * arch_config.out_channels,
bias=True,
)
self.gradient_checkpointing = False
self.__post_init__()
def forward(
self,
hidden_states: torch.Tensor,
encoder_hidden_states: torch.Tensor,
prior_token_id: torch.Tensor,
prior_token_drop: torch.Tensor,
timestep: torch.LongTensor,
target_size: torch.Tensor,
crop_coords: torch.Tensor,
attention_kwargs: Optional[Dict[str, Any]] = None,
kv_caches: Optional[GlmImageKVCache] = None,
kv_caches_mode: Optional[str] = None,
freqs_cis: Optional[Union[
Tuple[torch.Tensor, torch.Tensor],
List[Tuple[torch.Tensor, torch.Tensor]],
]] = None,
guidance: torch.Tensor = None,
**kwargs,
) -> torch.Tensor:
if kv_caches is not None:
kv_caches.set_mode(kv_caches_mode)
batch_size, num_channels, height, width = hidden_states.shape
if isinstance(encoder_hidden_states, list):
encoder_hidden_states = encoder_hidden_states[0]
# 1. RoPE
image_rotary_emb = freqs_cis
if image_rotary_emb is None:
image_rotary_emb = self.rotary_emb(hidden_states)
# 2. Patch & Timestep embeddings
p = self.patch_size
post_patch_height = height // p
post_patch_width = width // p
hidden_states = self.image_projector(hidden_states)
encoder_hidden_states = self.glyph_projector(encoder_hidden_states)
prior_embedding = self.prior_token_embedding(prior_token_id)
# Zero dropped priors by multiply: boolean indexing + .any() syncs each step.
keep = (~prior_token_drop).to(device=prior_embedding.device, dtype=prior_embedding.dtype)
while keep.dim() < prior_embedding.dim():
keep = keep.unsqueeze(-1)
prior_embedding = prior_embedding * keep
prior_hidden_states = self.prior_projector(prior_embedding)
hidden_states = hidden_states + prior_hidden_states
temb = self.time_condition_embed(timestep, target_size, crop_coords, hidden_states.dtype)
temb = F.silu(temb)
# 3. Transformer blocks
for idx, block in enumerate(self.transformer_blocks):
hidden_states, encoder_hidden_states = block(
hidden_states,
encoder_hidden_states,
temb,
image_rotary_emb,
attention_kwargs,
kv_cache=kv_caches[idx] if kv_caches is not None else None,
)
# 4. Output norm & projection
hidden_states = self.norm_out(hidden_states, temb)
hidden_states = self.proj_out(hidden_states)
# 5. Unpatchify
hidden_states = hidden_states.reshape(batch_size, post_patch_height, post_patch_width, -1, p, p)
output = hidden_states.permute(0, 3, 1, 4, 2, 5).flatten(4, 5).flatten(2, 3)
return output.float()
EntryClass = GlmImageTransformer2DModel