[Model] Add Support for Multimodal Granite Models (#10291)

Signed-off-by: Alex-Brooks <Alex.Brooks@ibm.com>
Co-authored-by: Cyrus Leung <cyrus.tl.leung@gmail.com>

vllm/model_executor/models/clip.py

@@ -21,7 +21,8 @@ from vllm.model_executor.layers.quantization import QuantizationConfig
 from vllm.model_executor.model_loader.weight_utils import default_weight_loader
 from vllm.multimodal.utils import (cached_get_tokenizer,
                                    consecutive_placeholder_ranges,
-                                   repeat_and_pad_placeholder_tokens)
+                                   repeat_and_pad_placeholder_tokens,
+                                   resolve_visual_encoder_outputs)
 from vllm.sequence import SequenceData
 
 from .utils import get_vit_attn_backend
@@ -389,12 +390,20 @@ class CLIPEncoder(nn.Module):
             for layer_idx in range(num_hidden_layers)
         ])
 
-    def forward(self, inputs_embeds: torch.Tensor):
-
+    def forward(
+        self, inputs_embeds: torch.Tensor, return_all_hidden_states: bool
+    ) -> Union[torch.Tensor, list[torch.Tensor]]:
+        hidden_states_pool = []
         hidden_states = inputs_embeds
+
         for encoder_layer in self.layers:
             hidden_states = encoder_layer(hidden_states)
-
+            if return_all_hidden_states:
+                hidden_states_pool.append(hidden_states)
+        # If we have multiple feature sample layers, we return all hidden
+        # states in order and grab the ones we need by index.
+        if return_all_hidden_states:
+            return hidden_states_pool
         return hidden_states
 
 
@@ -419,6 +428,7 @@ class CLIPVisionTransformer(nn.Module):
         # NOTE: This typo of "layrnorm" is not fixed on purpose to match
         # the original transformers code and name of the model weights.
         self.pre_layrnorm = nn.LayerNorm(embed_dim, eps=config.layer_norm_eps)
+
         self.encoder = CLIPEncoder(
             config=config,
             quant_config=quant_config,
@@ -446,16 +456,26 @@ class CLIPVisionTransformer(nn.Module):
     def forward(
         self,
         pixel_values: torch.Tensor,
+        feature_sample_layers: Optional[list[int]] = None,
     ) -> torch.Tensor:
 
         hidden_states = self.embeddings(pixel_values)
         hidden_states = self.pre_layrnorm(hidden_states)
-        hidden_states = self.encoder(inputs_embeds=hidden_states)
 
-        if self.post_layernorm is None:
-            return hidden_states
+        return_all_hidden_states = feature_sample_layers is not None
+
+        # Produces either the last layer output or all of the hidden states,
+        # depending on if we have feature_sample_layers or not
+        encoder_outputs = self.encoder(
+            inputs_embeds=hidden_states,
+            return_all_hidden_states=return_all_hidden_states)
+
+        # Handle post-norm (if applicable) and stacks feature layers if needed
+        encoder_outputs = resolve_visual_encoder_outputs(
+            encoder_outputs, feature_sample_layers, self.post_layernorm,
+            self.config.num_hidden_layers)
 
-        return self.post_layernorm(hidden_states)
+        return encoder_outputs
 
 
 class CLIPVisionModel(nn.Module):
@@ -478,11 +498,14 @@ class CLIPVisionModel(nn.Module):
             quant_config=quant_config,
             num_hidden_layers_override=num_hidden_layers_override,
             require_post_norm=require_post_norm,
-            prefix=f"{prefix}.vision_model",
-        )
+            prefix=f"{prefix}.vision_model")
 
-    def forward(self, pixel_values: torch.Tensor) -> torch.Tensor:
-        return self.vision_model(pixel_values)
+    def forward(
+        self,
+        pixel_values: torch.Tensor,
+        feature_sample_layers: Optional[list[int]] = None,
+    ) -> torch.Tensor:
+        return self.vision_model(pixel_values, feature_sample_layers)
 
     @property
     def device(self):

vllm/model_executor/models/llava.py

@@ -204,7 +204,41 @@ def input_processor_for_llava(ctx: InputContext, inputs: DecoderOnlyInputs):
 
 class LlavaLikeConfig(Protocol):
     vision_config: PretrainedConfig
-    vision_feature_layer: int
+    vision_feature_layer: Union[int, List[int]]
+
+
+def _get_num_hidden_layers(hf_config: LlavaLikeConfig) -> int:
+    """Determine the number of hidden layers to initialize up to in the
+    visual encoder.
+    
+    Args:
+        hf_config: Model config with vision feature layer(s).
+    """
+    feature_layers = hf_config.vision_feature_layer
+    num_hidden_layers = hf_config.vision_config.num_hidden_layers
+    # If we have one feature layer, initialize up to that layer
+    if isinstance(feature_layers, int):
+        return _get_layer_index(feature_layers, num_hidden_layers)
+    # If we have multiple feature layers, initialize up to the deepest one
+    elif isinstance(feature_layers, (list, tuple)):
+        return max(
+            _get_layer_index(idx, num_hidden_layers) for idx in feature_layers)
+    raise TypeError(f"vision_layer_feature type: {type(feature_layers)}"
+                    " is not supported")
+
+
+def _get_layer_index(feature_layer_index: int, num_hidden_layers: int) -> int:
+    """Given an signed vision feature layer, get the number of hidden layers
+    needed to leverage it.
+
+    Args:
+        feature_layer_index: Index of a required layer in the visual encoder.
+        num_hidden_layers: The total number of hidden layers in the visual
+            encoder.
+    """
+    if feature_layer_index < 0:
+        return num_hidden_layers + feature_layer_index + 1
+    return feature_layer_index + 1
 
 
 def init_vision_tower_for_llava(
@@ -216,13 +250,8 @@ def init_vision_tower_for_llava(
 ):
     vision_config = hf_config.vision_config
 
-    # Initialize the vision tower only up to the required feature layer
-    vision_feature_layer = hf_config.vision_feature_layer
-    if vision_feature_layer < 0:
-        num_hidden_layers = hf_config.vision_config.num_hidden_layers \
-            + vision_feature_layer + 1
-    else:
-        num_hidden_layers = vision_feature_layer + 1
+    # Initialize the vision tower only up to the deepest required feature layer
+    num_hidden_layers = _get_num_hidden_layers(hf_config)
 
     if isinstance(vision_config, CLIPVisionConfig):
         return CLIPVisionModel(

vllm/model_executor/models/llava_next.py

@@ -288,6 +288,21 @@ class LlavaNextForConditionalGeneration(nn.Module, SupportsMultiModal,
         pooler_config = vllm_config.model_config.pooler_config
         multimodal_config = vllm_config.model_config.multimodal_config
 
+        vision_feature_layer = config.vision_feature_layer
+        # Determine the layer up to which we will initialize the vision tower
+        if isinstance(vision_feature_layer, int):
+            vision_hidden_size = config.vision_config.hidden_size
+            self.feature_sample_layers = None
+        # Used for multimodal granite models to control encoder outputs
+        elif isinstance(vision_feature_layer, (list, tuple)):
+            vision_hidden_size = config.vision_config.hidden_size * len(
+                vision_feature_layer)
+            self.feature_sample_layers = vision_feature_layer
+        else:
+            raise TypeError(
+                f"vision_layer_feature type: {type(vision_feature_layer)}"
+                " is not supported")
+
         self.config = config
         self.multimodal_config = multimodal_config
 
@@ -300,7 +315,7 @@ class LlavaNextForConditionalGeneration(nn.Module, SupportsMultiModal,
         self.image_newline = nn.Parameter(
             torch.empty(config.text_config.hidden_size))
         self.multi_modal_projector = LlavaMultiModalProjector(
-            vision_hidden_size=config.vision_config.hidden_size,
+            vision_hidden_size=vision_hidden_size,
             text_hidden_size=config.text_config.hidden_size,
             projector_hidden_act=config.projector_hidden_act)
 
@@ -419,7 +434,8 @@ class LlavaNextForConditionalGeneration(nn.Module, SupportsMultiModal,
 
         # NOTE: we skip the step to select the vision feature layer since
         # this is already done inside the vision tower
-        image_features = vision_tower(pixel_values)
+        image_features = vision_tower(
+            pixel_values, feature_sample_layers=self.feature_sample_layers)
 
         return self._select_image_features(
             image_features,

vllm/model_executor/models/pixtral.py

@@ -33,7 +33,8 @@ from vllm.model_executor.sampling_metadata import SamplingMetadata
 from vllm.multimodal import MULTIMODAL_REGISTRY, MultiModalKwargs
 from vllm.multimodal.inputs import PlaceholderRange
 from vllm.multimodal.utils import (cached_get_tokenizer,
-                                   consecutive_placeholder_ranges)
+                                   consecutive_placeholder_ranges,
+                                   resolve_visual_encoder_outputs)
 from vllm.sequence import IntermediateTensors, SequenceData
 from vllm.transformers_utils.processor import cached_get_processor
 from vllm.utils import is_list_of
@@ -970,9 +971,18 @@ class PixtralHFTransformer(nn.Module):
         x: torch.Tensor,
         attention_mask: torch.Tensor,
         position_embeddings: torch.Tensor,
+        return_all_hidden_states: bool,
     ) -> torch.Tensor:
+        hidden_states_pool = []
+
         for layer in self.layers:
             x = layer(x, attention_mask, position_embeddings)
+            if return_all_hidden_states:
+                hidden_states_pool.append(x)
+        # If we have multiple feature sample layers, we return all hidden
+        # states in order and grab the ones we need by index.
+        if return_all_hidden_states:
+            return hidden_states_pool
         return x
 
 
@@ -990,6 +1000,7 @@ class PixtralHFVisionModel(nn.Module):
         super().__init__()
 
         self.config = config
+
         self.patch_conv = nn.Conv2d(
             in_channels=config.num_channels,
             out_channels=config.hidden_size,
@@ -1024,6 +1035,7 @@ class PixtralHFVisionModel(nn.Module):
     def forward(
         self,
         pixel_values: List[torch.Tensor],
+        feature_sample_layers: Optional[list[int]] = None,
     ) -> torch.Tensor:
         """
         Args:
@@ -1031,6 +1043,9 @@ class PixtralHFVisionModel(nn.Module):
                 in pixel_values. This means it will be a list of tensors
                 because multiple requests batched can have multiple images,
                 each with their own shape potentially
+            feature_sample_layers: Layer indices whose features should be
+                concatenated and used as the visual encoder output. If none
+                are provided, the last layer is used.
 
         Returns:
             image_features: tensor of token features for
@@ -1065,8 +1080,15 @@ class PixtralHFVisionModel(nn.Module):
                 [p.shape[-2] * p.shape[-1] for p in patch_embeds_list],
                 patch_embeds)
 
-        out = self.transformer(patch_embeds, attention_mask,
-                               position_embedding)
+        return_all_hidden_states = feature_sample_layers is not None
+        out = self.transformer(
+            patch_embeds,
+            attention_mask,
+            position_embedding,
+            return_all_hidden_states=return_all_hidden_states)
+
+        out = resolve_visual_encoder_outputs(out, feature_sample_layers, None,
+                                             self.config.num_hidden_layers)
 
         return out
 

vllm/model_executor/models/siglip.py

@@ -25,7 +25,8 @@ from vllm.model_executor.layers.vocab_parallel_embedding import (
 from vllm.model_executor.model_loader.weight_utils import default_weight_loader
 from vllm.multimodal.utils import (cached_get_tokenizer,
                                    consecutive_placeholder_ranges,
-                                   repeat_and_pad_placeholder_tokens)
+                                   repeat_and_pad_placeholder_tokens,
+                                   resolve_visual_encoder_outputs)
 from vllm.sequence import SequenceData
 
 from .utils import get_vit_attn_backend
@@ -450,11 +451,19 @@ class SiglipEncoder(nn.Module):
     def forward(
         self,
         inputs_embeds: torch.Tensor,
-    ) -> torch.Tensor:
+        return_all_hidden_states: bool,
+    ) -> Union[torch.Tensor, list[torch.Tensor]]:
+        hidden_states_pool = []
         hidden_states = inputs_embeds
+
         for encoder_layer in self.layers:
             hidden_states, _ = encoder_layer(hidden_states)
-
+            if return_all_hidden_states:
+                hidden_states_pool.append(hidden_states)
+        # If we have multiple feature sample layers, we return all hidden
+        # states in order and grab the ones we need by index.
+        if return_all_hidden_states:
+            return hidden_states_pool
         return hidden_states
 
 
@@ -509,6 +518,7 @@ class SiglipVisionTransformer(nn.Module):
         embed_dim = config.hidden_size
 
         self.embeddings = SiglipVisionEmbeddings(config)
+
         self.encoder = SiglipEncoder(
             config,
             quant_config=quant_config,
@@ -546,23 +556,33 @@ class SiglipVisionTransformer(nn.Module):
         self,
         pixel_values: torch.Tensor,
         interpolate_pos_encoding: bool = True,
+        feature_sample_layers: Optional[list[int]] = None,
     ) -> torch.Tensor:
+
         hidden_states = self.embeddings(
             pixel_values,
             interpolate_pos_encoding=interpolate_pos_encoding,
         )
 
-        encoder_outputs = self.encoder(inputs_embeds=hidden_states)
+        return_all_hidden_states = feature_sample_layers is not None
+
+        # Produces either the last layer output or all of the hidden states,
+        # depending on if we have feature_sample_layers or not
+        encoder_outputs = self.encoder(
+            inputs_embeds=hidden_states,
+            return_all_hidden_states=return_all_hidden_states,
+        )
 
-        if self.post_layernorm is None:
-            return encoder_outputs
+        # Handle post-norm (if applicable) and stacks feature layers if needed
+        encoder_outputs = resolve_visual_encoder_outputs(
+            encoder_outputs, feature_sample_layers, self.post_layernorm,
+            self.config.num_hidden_layers)
 
-        last_hidden_state = self.post_layernorm(encoder_outputs)
-        # TODO: add this back when pooled_output is used in inference
+        # TODO: add this back when pooled_output is used in inference.
         # if self.use_head:
-        # pooled_output = self.head(last_hidden_state)
+        # pooled_output = self.head(encoder_outputs)
 
-        return last_hidden_state
+        return encoder_outputs
 
 
 class SiglipVisionModel(nn.Module):
@@ -595,10 +615,12 @@ class SiglipVisionModel(nn.Module):
         self,
         pixel_values: torch.Tensor,
         interpolate_pos_encoding: bool = False,
+        feature_sample_layers: Optional[list[int]] = None,
     ) -> torch.Tensor:
         return self.vision_model(
             pixel_values=pixel_values,
             interpolate_pos_encoding=interpolate_pos_encoding,
+            feature_sample_layers=feature_sample_layers,
         )
 
     def load_weights(self, weights: Iterable[Tuple[str,

vllm/multimodal/utils.py

@@ -6,6 +6,7 @@ from typing import Any, List, Optional, Tuple, TypeVar, Union
 
 import numpy as np
 import numpy.typing as npt
+import torch
 from PIL import Image
 
 import vllm.envs as envs
@@ -392,6 +393,49 @@ def encode_video_base64(frames: npt.NDArray):
     return ",".join(base64_frames)
 
 
+def resolve_visual_encoder_outputs(
+    encoder_outputs: Union[torch.Tensor, list[torch.Tensor]],
+    feature_sample_layers: Optional[list[int]],
+    post_layer_norm: Optional[torch.nn.LayerNorm],
+    max_possible_layers: int,
+) -> torch.Tensor:
+    """Given the outputs a visual encoder module that may correspond to the
+    output of the last layer, or a list of hidden states to be stacked,
+    handle post normalization and resolve it into a single output tensor.
+
+    Args:
+        encoder_outputs: Output of encoder's last layer or all hidden states.
+        feature_sample_layers: Optional layer indices to grab from the encoder
+            outputs; if provided, encoder outputs must be a list.
+        post_layer_norm: Post norm to apply to the output of the encoder.
+        max_possible_layers: Total layers in the fully loaded visual encoder.
+
+    """
+    if feature_sample_layers is None:
+        if post_layer_norm is not None:
+            return post_layer_norm(encoder_outputs)
+        return encoder_outputs
+
+    # Get the hidden states corresponding to the layer indices.
+    # Negative values are relative to the full visual encoder,
+    # so offset them depending on how many layers were loaded.
+    # NOTE: this assumes that encoder_outputs contains a list
+    # of hidden states in the same order as the encoder layers
+    # that produced them.
+    offset = max_possible_layers - len(encoder_outputs)
+    hs_pool = [
+        encoder_outputs[layer_idx]
+        if layer_idx >= 0 else encoder_outputs[layer_idx + offset]
+        for layer_idx in feature_sample_layers
+    ]
+
+    # Apply post-norm on the final hidden state if we are using it
+    uses_last_layer = feature_sample_layers[-1] in (len(hs_pool) - 1, -1)
+    if post_layer_norm is not None and uses_last_layer:
+        hs_pool[-1] = post_layer_norm(encoder_outputs)
+    return torch.cat(hs_pool, dim=-1)
+
+
 # Utilities for input processors
 _T = TypeVar("_T", str, int)