huggingface · a-r-r-o-w · Jul 8, 2025 · Mar 31, 2025 · Mar 31, 2025 · Mar 31, 2025
diff --git a/docs/source/en/api/cache.md b/docs/source/en/api/cache.md
@@ -28,3 +28,9 @@ Cache methods speedup diffusion transformers by storing and reusing intermediate
 [[autodoc]] FasterCacheConfig
 
 [[autodoc]] apply_faster_cache
+
+### FirstBlockCacheConfig
+
+[[autodoc]] FirstBlockCacheConfig
+
+[[autodoc]] apply_first_block_cache
diff --git a/src/diffusers/__init__.py b/src/diffusers/__init__.py
@@ -133,9 +133,11 @@
     _import_structure["hooks"].extend(
         [
             "FasterCacheConfig",
+            "FirstBlockCacheConfig",
             "HookRegistry",
             "PyramidAttentionBroadcastConfig",
             "apply_faster_cache",
+            "apply_first_block_cache",
             "apply_pyramid_attention_broadcast",
         ]
     )
@@ -751,9 +753,11 @@
     else:
         from .hooks import (
             FasterCacheConfig,
+            FirstBlockCacheConfig,
             HookRegistry,
             PyramidAttentionBroadcastConfig,
             apply_faster_cache,
+            apply_first_block_cache,
             apply_pyramid_attention_broadcast,
         )
         from .models import (

diff --git a/src/diffusers/hooks/__init__.py b/src/diffusers/hooks/__init__.py
@@ -1,8 +1,23 @@
+# Copyright 2024 The HuggingFace Team. 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.
+
 from ..utils import is_torch_available
 
 
 if is_torch_available():
     from .faster_cache import FasterCacheConfig, apply_faster_cache
+    from .first_block_cache import FirstBlockCacheConfig, apply_first_block_cache
     from .group_offloading import apply_group_offloading
     from .hooks import HookRegistry, ModelHook
     from .layerwise_casting import apply_layerwise_casting, apply_layerwise_casting_hook

diff --git a/src/diffusers/hooks/_common.py b/src/diffusers/hooks/_common.py
@@ -0,0 +1,30 @@
+# Copyright 2024 The HuggingFace Team. 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.
+
+from ..models.attention_processor import Attention, MochiAttention
+
+
+_ATTENTION_CLASSES = (Attention, MochiAttention)
+
+_SPATIAL_TRANSFORMER_BLOCK_IDENTIFIERS = ("blocks", "transformer_blocks", "single_transformer_blocks", "layers")
+_TEMPORAL_TRANSFORMER_BLOCK_IDENTIFIERS = ("temporal_transformer_blocks",)
+_CROSS_TRANSFORMER_BLOCK_IDENTIFIERS = ("blocks", "transformer_blocks", "layers")
+
+_ALL_TRANSFORMER_BLOCK_IDENTIFIERS = tuple(
+    {
+        *_SPATIAL_TRANSFORMER_BLOCK_IDENTIFIERS,
+        *_TEMPORAL_TRANSFORMER_BLOCK_IDENTIFIERS,
+        *_CROSS_TRANSFORMER_BLOCK_IDENTIFIERS,
+    }
+)
diff --git a/src/diffusers/hooks/_helpers.py b/src/diffusers/hooks/_helpers.py
@@ -0,0 +1,264 @@
+# Copyright 2025 The HuggingFace Team. 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
+from dataclasses import dataclass
+from typing import Any, Callable, Dict, Type
+
+
+@dataclass
+class AttentionProcessorMetadata:
+    skip_processor_output_fn: Callable[[Any], Any]
+
+
+@dataclass
+class TransformerBlockMetadata:
+    return_hidden_states_index: int = None
+    return_encoder_hidden_states_index: int = None
+
+    _cls: Type = None
+    _cached_parameter_indices: Dict[str, int] = None
+
+    def _get_parameter_from_args_kwargs(self, identifier: str, args=(), kwargs=None):
+        kwargs = kwargs or {}
+        if identifier in kwargs:
+            return kwargs[identifier]
+        if self._cached_parameter_indices is not None:
+            return args[self._cached_parameter_indices[identifier]]
+        if self._cls is None:
+            raise ValueError("Model class is not set for metadata.")
+        parameters = list(inspect.signature(self._cls.forward).parameters.keys())
+        parameters = parameters[1:]  # skip `self`
+        self._cached_parameter_indices = {param: i for i, param in enumerate(parameters)}
+        if identifier not in self._cached_parameter_indices:
+            raise ValueError(f"Parameter '{identifier}' not found in function signature but was requested.")
+        index = self._cached_parameter_indices[identifier]
+        if index >= len(args):
+            raise ValueError(f"Expected {index} arguments but got {len(args)}.")
+        return args[index]
+
+
+class AttentionProcessorRegistry:
+    _registry = {}
+    # TODO(aryan): this is only required for the time being because we need to do the registrations
+    # for classes. If we do it eagerly, i.e. call the functions in global scope, we will get circular
+    # import errors because of the models imported in this file.
+    _is_registered = False
+
+    @classmethod
+    def register(cls, model_class: Type, metadata: AttentionProcessorMetadata):
+        cls._register()
+        cls._registry[model_class] = metadata
+
+    @classmethod
+    def get(cls, model_class: Type) -> AttentionProcessorMetadata:
+        cls._register()
+        if model_class not in cls._registry:
+            raise ValueError(f"Model class {model_class} not registered.")
+        return cls._registry[model_class]
+
+    @classmethod
+    def _register(cls):
+        if cls._is_registered:
+            return
+        cls._is_registered = True
+        _register_attention_processors_metadata()
+
+
+class TransformerBlockRegistry:
+    _registry = {}
+    # TODO(aryan): this is only required for the time being because we need to do the registrations
+    # for classes. If we do it eagerly, i.e. call the functions in global scope, we will get circular
+    # import errors because of the models imported in this file.
+    _is_registered = False
+
+    @classmethod
+    def register(cls, model_class: Type, metadata: TransformerBlockMetadata):
+        cls._register()
+        metadata._cls = model_class
+        cls._registry[model_class] = metadata
+
+    @classmethod
+    def get(cls, model_class: Type) -> TransformerBlockMetadata:
+        cls._register()
+        if model_class not in cls._registry:
+            raise ValueError(f"Model class {model_class} not registered.")
+        return cls._registry[model_class]
+
+    @classmethod
+    def _register(cls):
+        if cls._is_registered:
+            return
+        cls._is_registered = True
+        _register_transformer_blocks_metadata()
+
+
+def _register_attention_processors_metadata():
+    from ..models.attention_processor import AttnProcessor2_0
+    from ..models.transformers.transformer_cogview4 import CogView4AttnProcessor
+
+    # AttnProcessor2_0
+    AttentionProcessorRegistry.register(
+        model_class=AttnProcessor2_0,
+        metadata=AttentionProcessorMetadata(
+            skip_processor_output_fn=_skip_proc_output_fn_Attention_AttnProcessor2_0,
+        ),
+    )
+
+    # CogView4AttnProcessor
+    AttentionProcessorRegistry.register(
+        model_class=CogView4AttnProcessor,
+        metadata=AttentionProcessorMetadata(
+            skip_processor_output_fn=_skip_proc_output_fn_Attention_CogView4AttnProcessor,
+        ),
+    )
+
+
+def _register_transformer_blocks_metadata():
+    from ..models.attention import BasicTransformerBlock
+    from ..models.transformers.cogvideox_transformer_3d import CogVideoXBlock
+    from ..models.transformers.transformer_cogview4 import CogView4TransformerBlock
+    from ..models.transformers.transformer_flux import FluxSingleTransformerBlock, FluxTransformerBlock
+    from ..models.transformers.transformer_hunyuan_video import (
+        HunyuanVideoSingleTransformerBlock,
+        HunyuanVideoTokenReplaceSingleTransformerBlock,
+        HunyuanVideoTokenReplaceTransformerBlock,
+        HunyuanVideoTransformerBlock,
+    )
+    from ..models.transformers.transformer_ltx import LTXVideoTransformerBlock
+    from ..models.transformers.transformer_mochi import MochiTransformerBlock
+    from ..models.transformers.transformer_wan import WanTransformerBlock
+
+    # BasicTransformerBlock
+    TransformerBlockRegistry.register(
+        model_class=BasicTransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=0,
+            return_encoder_hidden_states_index=None,
+        ),
+    )
+
+    # CogVideoX
+    TransformerBlockRegistry.register(
+        model_class=CogVideoXBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=0,
+            return_encoder_hidden_states_index=1,
+        ),
+    )
+
+    # CogView4
+    TransformerBlockRegistry.register(
+        model_class=CogView4TransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=0,
+            return_encoder_hidden_states_index=1,
+        ),
+    )
+
+    # Flux
+    TransformerBlockRegistry.register(
+        model_class=FluxTransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=1,
+            return_encoder_hidden_states_index=0,
+        ),
+    )
+    TransformerBlockRegistry.register(
+        model_class=FluxSingleTransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=1,
+            return_encoder_hidden_states_index=0,
+        ),
+    )
+
+    # HunyuanVideo
+    TransformerBlockRegistry.register(
+        model_class=HunyuanVideoTransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=0,
+            return_encoder_hidden_states_index=1,
+        ),
+    )
+    TransformerBlockRegistry.register(
+        model_class=HunyuanVideoSingleTransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=0,
+            return_encoder_hidden_states_index=1,
+        ),
+    )
+    TransformerBlockRegistry.register(
+        model_class=HunyuanVideoTokenReplaceTransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=0,
+            return_encoder_hidden_states_index=1,
+        ),
+    )
+    TransformerBlockRegistry.register(
+        model_class=HunyuanVideoTokenReplaceSingleTransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=0,
+            return_encoder_hidden_states_index=1,
+        ),
+    )
+
+    # LTXVideo
+    TransformerBlockRegistry.register(
+        model_class=LTXVideoTransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=0,
+            return_encoder_hidden_states_index=None,
+        ),
+    )
+
+    # Mochi
+    TransformerBlockRegistry.register(
+        model_class=MochiTransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=0,
+            return_encoder_hidden_states_index=1,
+        ),
+    )
+
+    # Wan
+    TransformerBlockRegistry.register(
+        model_class=WanTransformerBlock,
+        metadata=TransformerBlockMetadata(
+            return_hidden_states_index=0,
+            return_encoder_hidden_states_index=None,
+        ),
+    )
+
+
+# fmt: off
+def _skip_attention___ret___hidden_states(self, *args, **kwargs):
+    hidden_states = kwargs.get("hidden_states", None)
+    if hidden_states is None and len(args) > 0:
+        hidden_states = args[0]
+    return hidden_states
+
+
+def _skip_attention___ret___hidden_states___encoder_hidden_states(self, *args, **kwargs):
+    hidden_states = kwargs.get("hidden_states", None)
+    encoder_hidden_states = kwargs.get("encoder_hidden_states", None)
+    if hidden_states is None and len(args) > 0:
+        hidden_states = args[0]
+    if encoder_hidden_states is None and len(args) > 1:
+        encoder_hidden_states = args[1]
+    return hidden_states, encoder_hidden_states
+
+
+_skip_proc_output_fn_Attention_AttnProcessor2_0 = _skip_attention___ret___hidden_states
+_skip_proc_output_fn_Attention_CogView4AttnProcessor = _skip_attention___ret___hidden_states___encoder_hidden_states
+# fmt: on