molmo.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project

import math
from collections.abc import Iterable, Mapping, Sequence
from dataclasses import dataclass
from functools import cached_property, partial
from itertools import islice
from typing import Annotated

import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F
from einops import rearrange
from transformers import BatchFeature, PretrainedConfig, ProcessorMixin, TensorType
from transformers.image_utils import ImageInput
from transformers.tokenization_utils_base import TextInput

from vllm.attention import Attention
from vllm.attention.layer import MultiHeadAttention
from vllm.compilation.decorators import support_torch_compile
from vllm.config import CacheConfig, VllmConfig
from vllm.config.multimodal import BaseDummyOptions
from vllm.distributed import (
    get_pp_group,
    get_tensor_model_parallel_rank,
    get_tensor_model_parallel_world_size,
    split_tensor_along_last_dim,
    tensor_model_parallel_all_gather,
)
from vllm.model_executor.layers.activation import MulAndSilu, QuickGELU, SiluAndMul
from vllm.model_executor.layers.layernorm import RMSNorm
from vllm.model_executor.layers.linear import (
    ColumnParallelLinear,
    MergedColumnParallelLinear,
    QKVParallelLinear,
    RowParallelLinear,
)
from vllm.model_executor.layers.logits_processor import LogitsProcessor
from vllm.model_executor.layers.quantization import QuantizationConfig
from vllm.model_executor.layers.rotary_embedding import get_rope
from vllm.model_executor.layers.vocab_parallel_embedding import (
    ParallelLMHead,
    VocabParallelEmbedding,
)
from vllm.model_executor.model_loader.weight_utils import default_weight_loader
from vllm.model_executor.models.module_mapping import MultiModelKeys
from vllm.multimodal import MULTIMODAL_REGISTRY
from vllm.multimodal.inputs import (
    MultiModalDataDict,
    MultiModalFieldConfig,
    MultiModalKwargsItems,
)
from vllm.multimodal.parse import ImageProcessorItems, ImageSize, MultiModalDataItems
from vllm.multimodal.processing import (
    BaseMultiModalProcessor,
    BaseProcessingInfo,
    PromptIndexTargets,
    PromptInsertion,
    PromptUpdate,
    PromptUpdateDetails,
)
from vllm.multimodal.profiling import BaseDummyInputsBuilder
from vllm.sequence import IntermediateTensors
from vllm.utils.tensor_schema import TensorSchema, TensorShape

from .interfaces import (
    MultiModalEmbeddings,
    SupportsLoRA,
    SupportsMultiModal,
    SupportsPP,
    SupportsQuant,
)
from .utils import (
    AutoWeightsLoader,
    WeightsMapper,
    is_pp_missing_parameter,
    make_empty_intermediate_tensors_factory,
    make_layers,
    maybe_prefix,
)

# TODO: hard-coded for now. Consider making it configurable.
VIT_LAYERS = [-2, -9]
NUM_PREFIX_TOKENS = 1
ADDITIONAL_VOCAB_SIZE = 128
IMAGE_PATCH_TOKEN = "<im_patch>"
IM_COL_TOKEN = "<im_col>"
IM_START_TOKEN = "<im_start>"
IM_END_TOKEN = "<im_end>"
POOLING_SIZE = 2


class MolmoImageInputs(TensorSchema):
    """
    Dimensions:
        - bn: Batch size * number of images
        - bnc: Batch size * number of images * number of crops (dynamic)
        - np: Number of patches
        - tp: Token sequence positions
        - pd: Patch dimension
    """

    images: Annotated[torch.Tensor, TensorShape("bnc", "np", "pd")]

    image_masks: Annotated[torch.Tensor | None, TensorShape("bnc", "np")]

    image_input_idx: Annotated[torch.Tensor, TensorShape("bnc", "tp")]
    """An index tensor that maps image features to their corresponding patch tokens."""

    num_crops: Annotated[torch.Tensor, TensorShape("bn")]


@dataclass
class VisionBackboneConfig:
    image_default_input_size: tuple[int, int] = (336, 336)
    image_patch_size: int = 14
    image_pos_patch_size: int = 14
    image_emb_dim: int = 1024
    image_num_heads: int = 16
    image_num_key_value_heads: int = 16
    image_num_layers: int = 23
    image_mlp_dim: int = 4096
    image_mlp_activations: str = "quick_gelu"
    image_num_pos: int = 577
    image_norm_eps: float = 1e-5

    def __post_init__(self):
        self.image_default_input_size = tuple(self.image_default_input_size)  # type: ignore[assignment]

    @property
    def image_num_patch(self):
        h, w = self.image_default_input_size
        return h // self.image_patch_size, w // self.image_patch_size


class ViTMLP(nn.Module):
    """MLP used in Vision Transformer."""

    def __init__(
        self,
        config: VisionBackboneConfig,
        quant_config: QuantizationConfig | None = None,
    ):
        super().__init__()
        self.w1 = ColumnParallelLinear(
            config.image_emb_dim,
            config.image_mlp_dim,
            bias=True,
            quant_config=quant_config,
        )
        # Activation function.
        assert config.image_mlp_activations == "quick_gelu"
        self.act = QuickGELU()
        self.w2 = RowParallelLinear(
            config.image_mlp_dim,
            config.image_emb_dim,
            bias=True,
            quant_config=quant_config,
        )

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        x, _ = self.w1(x)
        x = self.act(x)
        x, _ = self.w2(x)
        return x


class MultiHeadDotProductAttention(nn.Module):
    """Multi-head attention used in Vision Transformer."""

    def __init__(
        self,
        config: VisionBackboneConfig,
        use_bias: bool = True,
        nlayers: int = 1,
        quant_config: QuantizationConfig | None = None,
    ):
        super().__init__()

        self.hidden_size = config.image_emb_dim
        self.total_num_heads = config.image_num_heads
        tp_size = get_tensor_model_parallel_world_size()

        assert self.hidden_size % self.total_num_heads == 0
        assert self.total_num_heads % tp_size == 0

        self.num_heads = self.total_num_heads // tp_size
        self.head_dim = self.hidden_size // self.total_num_heads

        self.total_num_kv_heads = config.image_num_key_value_heads
        if self.total_num_kv_heads >= tp_size:
            assert self.total_num_kv_heads % tp_size == 0
        else:
            assert tp_size % self.total_num_kv_heads == 0

        self.num_kv_heads = max(1, self.total_num_kv_heads // tp_size)

        self.wq = ColumnParallelLinear(
            nlayers * self.hidden_size,
            self.total_num_heads * self.head_dim,
            bias=use_bias,
            quant_config=quant_config,
        )
        self.wk = ColumnParallelLinear(
            nlayers * self.hidden_size,
            self.total_num_kv_heads * self.head_dim,
            bias=use_bias,
            quant_config=quant_config,
        )
        self.wv = ColumnParallelLinear(
            nlayers * self.hidden_size,
            self.total_num_kv_heads * self.head_dim,
            bias=use_bias,
            quant_config=quant_config,
        )
        self.wo = RowParallelLinear(
            self.total_num_heads * self.head_dim,
            self.hidden_size,
            bias=use_bias,
            quant_config=quant_config,
        )

        self.scale = self.head_dim**-0.5
        self.attn = MultiHeadAttention(
            self.num_heads, self.head_dim, self.scale, num_kv_heads=self.num_kv_heads
        )

    def forward(
        self, inputs_q: torch.Tensor, inputs_kv: torch.Tensor | None = None
    ) -> torch.Tensor:
        if inputs_kv is not None:
            inputs_k = inputs_kv
            inputs_v = inputs_kv
        else:
            inputs_k = inputs_q
            inputs_v = inputs_q

        xq, _ = self.wq(inputs_q)
        xk, _ = self.wk(inputs_k)
        xv, _ = self.wv(inputs_v)

        output = self.attn(xq, xk, xv)
        output, _ = self.wo(output)

        return output


class ResidualAttentionBlock(nn.Module):
    """Residual attention block used in Vision Transformer."""

    def __init__(
        self,
        config: VisionBackboneConfig,
        quant_config: QuantizationConfig | None = None,
    ):
        super().__init__()
        self.attention = MultiHeadDotProductAttention(config, quant_config=quant_config)
        self.feed_forward = ViTMLP(config, quant_config)
        self.attention_norm = nn.LayerNorm(
            config.image_emb_dim,
            eps=config.image_norm_eps,
        )
        self.ffn_norm = nn.LayerNorm(
            config.image_emb_dim,
            eps=config.image_norm_eps,
        )

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        x = x + self.attention(self.attention_norm(x))
        x = x + self.feed_forward(self.ffn_norm(x))
        return x


class BlockCollection(nn.Module):
    """Collection of residual attention blocks used in Vision Transformer."""

    def __init__(
        self,
        config: VisionBackboneConfig,
        quant_config: QuantizationConfig | None = None,
    ):
        super().__init__()
        self.resblocks = nn.ModuleList(
            [
                ResidualAttentionBlock(config, quant_config)
                for _ in range(config.image_num_layers)
            ]
        )

    def forward(self, x: torch.Tensor) -> list[torch.Tensor]:
        hidden_states = []
        for r in self.resblocks:
            x = r(x)
            hidden_states.append(x)
        return hidden_states


def _expand_token(token: torch.Tensor, batch_size: int) -> torch.Tensor:
    return token.view(1, 1, -1).expand(batch_size, -1, -1)


class VisionTransformer(nn.Module):
    """Vision Transformer used in Vision Backbone."""

    def __init__(
        self,
        config: VisionBackboneConfig,
        quant_config: QuantizationConfig | None = None,
    ):
        super().__init__()
        scale = config.image_emb_dim**-0.5
        self.patch_num = config.image_num_patch
        self.class_embedding = nn.Parameter(torch.randn(config.image_emb_dim) * scale)
        self.num_prefix_tokens: int = NUM_PREFIX_TOKENS
        self.positional_embedding = nn.Parameter(
            torch.randn(config.image_num_pos, config.image_emb_dim) * scale
        )
        image_patch_size = config.image_patch_size
        self.patch_embedding = nn.Linear(
            image_patch_size * image_patch_size * 3,
            config.image_emb_dim,
            bias=False,
        )
        self.pre_ln = nn.LayerNorm(config.image_emb_dim, eps=config.image_norm_eps)
        self.transformer = BlockCollection(config, quant_config)

    def add_pos_emb(self, x: torch.Tensor, patch_num: int) -> torch.Tensor:
        cls_emb = self.positional_embedding[0:1]
        pos_emb = self.positional_embedding[1:]

        pos_emb = pos_emb.reshape(
            (
                int(math.sqrt(pos_emb.shape[0])),
                int(math.sqrt(pos_emb.shape[0])),
                pos_emb.shape[1],
            )
        )

        (patch_num_0, patch_num_1) = patch_num

        if pos_emb.shape[0] != patch_num_0 or pos_emb.shape[1] != patch_num_1:
            # from https://github.com/facebookresearch/mae/blob/main/util/pos_embed.py
            pos_emb = pos_emb.unsqueeze(0).permute(0, 3, 1, 2)
            pos_emb = F.interpolate(
                pos_emb,
                size=(patch_num_0, patch_num_1),
                mode="bicubic",
                align_corners=False,
                antialias=True,
            )
            pos_emb = pos_emb.permute(0, 2, 3, 1).squeeze(0)

        pos_emb = pos_emb.reshape(-1, pos_emb.shape[-1])
        x = x + torch.cat([cls_emb[None, :, :], pos_emb[None, :, :]], dim=1).to(x.dtype)
        return x

    def forward(
        self, x: torch.Tensor, patch_num: int | None = None
    ) -> list[torch.Tensor]:
        """
        : param x: (batch_size, num_patch, n_pixels)
        """
        if patch_num is None:
            patch_num = self.patch_num
        B, N, D = x.shape

        x = self.patch_embedding(x)

        # class embeddings and positional embeddings
        x = torch.cat(
            [_expand_token(self.class_embedding, x.shape[0]).to(x.dtype), x], dim=1
        )
        x = self.add_pos_emb(x, patch_num)

        x = self.pre_ln(x)

        hidden_states = self.transformer(x)
        return hidden_states


class MolmoAttention(nn.Module):
    """Molmo's LLM attention."""

    def __init__(
        self,
        config: PretrainedConfig,
        cache_config: CacheConfig | None = None,
        quant_config: QuantizationConfig | None = None,
        prefix: str = "",
    ) -> None:
        super().__init__()
        self.hidden_size = config.hidden_size
        self.tp_size = get_tensor_model_parallel_world_size()
        self.total_num_heads = config.num_attention_heads

        assert self.hidden_size % self.total_num_heads == 0
        assert self.total_num_heads % self.tp_size == 0

        self.num_heads = self.total_num_heads // self.tp_size
        self.total_num_kv_heads = config.num_key_value_heads or self.total_num_heads
        if self.total_num_kv_heads >= self.tp_size:
            assert self.total_num_kv_heads % self.tp_size == 0
        else:
            assert self.tp_size % self.total_num_kv_heads == 0

        self.num_kv_heads = max(1, self.total_num_kv_heads // self.tp_size)
        self.head_dim = self.hidden_size // self.total_num_heads
        self.q_size = self.num_heads * self.head_dim
        self.kv_size = self.num_kv_heads * self.head_dim
        self.max_position_embeddings = config.max_position_embeddings
        self.rope_theta = config.rope_theta

        # Attention input projection. Projects x -> (q, k, v)
        self.qkv_proj = QKVParallelLinear(
            self.hidden_size,
            self.head_dim,
            self.total_num_heads,
            self.total_num_kv_heads,
            bias=config.qkv_bias,
            quant_config=quant_config,
        )

        self.tp_rank: int | None = None
        self.k_norm: nn.Module | None = None
        self.q_norm: nn.Module | None = None
        if config.attention_layer_norm:
            self.tp_rank = get_tensor_model_parallel_rank()
            self.k_norm = RMSNorm(
                self.total_num_kv_heads * self.head_dim, eps=config.layer_norm_eps
            )
            self.q_norm = RMSNorm(config.hidden_size, eps=config.layer_norm_eps)

        # Rotary embeddings.
        self.rotary_emb = get_rope(
            self.head_dim,
            rotary_dim=self.head_dim,
            max_position=self.max_position_embeddings,
            base=self.rope_theta,
        )
        self.scaling = self.head_dim**-0.5
        self.attn = Attention(
            self.num_heads,
            self.head_dim,
            self.scaling,
            num_kv_heads=self.num_kv_heads,
            cache_config=cache_config,
            quant_config=quant_config,
            prefix=f"{prefix}.attn",
        )

        # Attention output projection.
        self.o_proj = RowParallelLinear(
            self.total_num_heads * self.head_dim,
            self.hidden_size,
            bias=False,
            quant_config=quant_config,
        )

    def _apply_qk_norm(
        self, q: torch.Tensor, k: torch.Tensor
    ) -> tuple[torch.Tensor, torch.Tensor]:
        if self.tp_size > 1:
            q = tensor_model_parallel_all_gather(q.contiguous())
            k = tensor_model_parallel_all_gather(k.contiguous())
        q = self.q_norm(q)
        k = self.k_norm(k)
        if self.tp_size > 1:
            splitter = partial(split_tensor_along_last_dim, num_partitions=self.tp_size)
            q = splitter(q)[self.tp_rank]
            k = splitter(k)[self.tp_rank]
        return q, k

    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
    ) -> torch.Tensor:
        qkv, _ = self.qkv_proj(hidden_states)
        q, k, v = qkv.split([self.q_size, self.kv_size, self.kv_size], dim=-1)
        if self.q_norm is not None and self.k_norm is not None:
            q, k = self._apply_qk_norm(q, k)
        q, k = self.rotary_emb(positions, q, k)
        attn_output = self.attn(q, k, v)
        output, _ = self.o_proj(attn_output)
        return output


class LanguageModelMLP(nn.Module):
    """Molmo's LLM mlp."""

    def __init__(
        self,
        config: PretrainedConfig,
        input_dim: int | None = None,
        quant_config: QuantizationConfig | None = None,
    ) -> None:
        super().__init__()
        self.hidden_size = config.hidden_size
        self.intermediate_size = config.intermediate_size // 2

        self.gate_up_proj = MergedColumnParallelLinear(
            input_dim or self.hidden_size,
            [self.intermediate_size] * 2,
            bias=False,
            quant_config=quant_config,
        )
        # Activation function.
        self.act_fn = MulAndSilu()
        # Feed-forward output projection.
        self.down_proj = RowParallelLinear(
            self.intermediate_size,
            self.hidden_size,
            bias=False,
            quant_config=quant_config,
        )

    def forward(
        self,
        x: torch.Tensor,
    ) -> torch.Tensor:
        gate_up, _ = self.gate_up_proj(x)
        x = self.act_fn(gate_up)
        x, _ = self.down_proj(x)
        return x


class ImageProjectorMLP(nn.Module):
    """Molmo's image_projector mlp."""

    def __init__(
        self,
        config: PretrainedConfig,
        input_dim: int | None = None,
        quant_config: QuantizationConfig | None = None,
    ) -> None:
        super().__init__()
        self.hidden_size = config.hidden_size
        self.intermediate_size = config.intermediate_size // 2

        self.merged_linear = MergedColumnParallelLinear(
            input_dim or self.hidden_size,
            [self.intermediate_size] * 2,
            bias=False,
            quant_config=quant_config,
        )
        # Activation function.
        self.act_fn = SiluAndMul()

        # Feed-forward output projection.
        self.down_proj = RowParallelLinear(
            self.intermediate_size,
            self.hidden_size,
            bias=False,
            quant_config=quant_config,
        )

    def forward(
        self,
        x: torch.Tensor,
    ) -> torch.Tensor:
        gate_up, _ = self.merged_linear(x)
        x = self.act_fn(gate_up)
        x, _ = self.down_proj(x)
        return x


class MolmoDecoderLayer(nn.Module):
    def __init__(
        self,
        config: PretrainedConfig,
        cache_config: CacheConfig | None = None,
        quant_config: QuantizationConfig | None = None,
        prefix: str = "",
    ) -> None:
        super().__init__()
        # Attention block.
        self.self_attn = MolmoAttention(
            config, cache_config, quant_config, prefix=f"{prefix}.self_attn"
        )

        # MLP block.
        self.mlp = LanguageModelMLP(config, quant_config=quant_config)

        # LayerNorm
        assert config.layer_norm_type == "rms"
        self.input_layernorm = RMSNorm(config.hidden_size, eps=config.layer_norm_eps)
        self.post_attention_layernorm = RMSNorm(
            config.hidden_size, eps=config.layer_norm_eps
        )

    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
        residual: torch.Tensor | None,
    ) -> tuple[torch.Tensor, tuple[torch.Tensor, torch.Tensor] | None]:
        # Self Attention
        if residual is None:
            residual = hidden_states
            hidden_states = self.input_layernorm(hidden_states)
        else:
            hidden_states, residual = self.input_layernorm(hidden_states, residual)
        hidden_states = self.self_attn(
            positions=positions,
            hidden_states=hidden_states,
        )

        hidden_states, residual = self.post_attention_layernorm(hidden_states, residual)
        hidden_states = self.mlp(hidden_states)
        return hidden_states, residual


class MolmoDecoderNormAfterLayer(MolmoDecoderLayer):
    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
        residual: torch.Tensor | None,
    ) -> tuple[torch.Tensor, tuple[torch.Tensor, torch.Tensor] | None]:
        # Self Attention
        residual = hidden_states
        hidden_states = self.self_attn(
            positions=positions,
            hidden_states=hidden_states,
        )

        hidden_states = self.input_layernorm(hidden_states)
        hidden_states = hidden_states + residual
        residual = hidden_states

        hidden_states = self.mlp(hidden_states)
        hidden_states = self.post_attention_layernorm(hidden_states)
        hidden_states = hidden_states + residual
        residual = None
        return hidden_states, residual


class MolmoVisionBackbone(nn.Module, SupportsQuant):
    packed_modules_mapping = {"merged_linear": ["gate_proj", "up_proj"]}

    def __init__(
        self,
        config: PretrainedConfig,
        vision_config: VisionBackboneConfig,
        quant_config: QuantizationConfig | None = None,
    ) -> None:
        super().__init__()
        self.vit_layers = VIT_LAYERS
        self.image_num_patch = vision_config.image_num_patch
        self.llm_patches_per_crop = (
            (self.image_num_patch[0] + 1) // POOLING_SIZE,
            (self.image_num_patch[1] + 1) // POOLING_SIZE,
        )
        self.image_vit = VisionTransformer(vision_config, quant_config=quant_config)
        self.num_prefix_tokens = self.image_vit.num_prefix_tokens
        assert self.num_prefix_tokens in {0, 1}, (
            "Only 0 or 1 prefix tokens are supported"
        )
        self.image_pooling_2d = MultiHeadDotProductAttention(
            vision_config, nlayers=len(self.vit_layers), quant_config=quant_config
        )
        self.image_projector = ImageProjectorMLP(
            config,
            input_dim=vision_config.image_emb_dim,
            quant_config=quant_config,
        )

        image_dim = vision_config.image_emb_dim * len(self.vit_layers)
        self.pad_embed = nn.Parameter(torch.zeros((2, image_dim)))

    @property
    def dtype(self) -> torch.dtype:
        return self.image_vit.patch_embedding.weight.dtype

    @property
    def device(self) -> torch.device:
        return self.image_vit.patch_embedding.weight.device

    def encode_image(self, images: torch.Tensor) -> torch.Tensor:
        """
        : param images: (batch_size, num_crops, num_patch, n_pixels)
        """
        B, T, N, D = images.shape

        mask = ~torch.all(images.view(B * T, N, D) == -1, dim=(1, 2), keepdim=True)

        images = images.view(B * T, N, D)
        image_features = self.image_vit(images)

        if self.vit_layers is not None:
            features = []
            for layer in self.vit_layers:
                features.append(image_features[layer])
            image_features = torch.cat(features, dim=-1)
        else:
            image_features = image_features[-1]

        if self.num_prefix_tokens > 0:
            image_features = image_features[:, 1:]

        image_features = image_features * mask
        image_features = image_features.view(B, T, N, -1)

        return image_features

    def forward(
        self,
        images: torch.Tensor,
        image_masks: torch.Tensor,
    ) -> torch.Tensor:
        # image_features: (batch_size, num_crops(=num_image), num_patch, nximage_emb_dim) # noqa: E501
        batch_size, num_image = images.shape[:2]
        images = images.to(device=self.device, dtype=self.dtype)
        image_features = self.encode_image(images)

        og_dtype = image_features.dtype
        assert image_masks is not None
        pad_embed = self.pad_embed[:, None, None, None, :]
        all_pad = image_masks == 0
        partial_pad = torch.logical_and(image_masks < 1, torch.logical_not(all_pad)).to(
            dtype=torch.float32
        )
        all_pad = all_pad.to(dtype=torch.float32)
        image_features = image_features + pad_embed[0] * torch.unsqueeze(all_pad, -1)
        image_features = image_features + pad_embed[1] * torch.unsqueeze(
            partial_pad, -1
        )

        image_features = image_features.to(og_dtype)

        image_features = image_features.reshape(
            (batch_size, num_image) + self.image_num_patch + (-1,),
        )

        if missing_w := self.image_num_patch[0] % POOLING_SIZE:
            # Padding for image pooling (see below)
            image_features = F.pad(
                image_features,
                (0, 0, 0, missing_w, 0, missing_w, 0, 0, 0, 0),
            )

        # image pooling
        image_features = rearrange(
            image_features,
            "b n (h dh) (w dw) c -> (b n h w) (dh dw) c",
            dh=POOLING_SIZE,
            dw=POOLING_SIZE,
        )

        query = image_features.mean(-2, keepdim=True)
        image_features = self.image_pooling_2d(query, image_features)

        h, w = self.llm_patches_per_crop
        image_features = image_features.view(batch_size, num_image, h * w, -1)

        image_features = self.image_projector(image_features)

        # image_features: (batch_size, num_image, num_patch, d_model)
        return image_features

    def load_weights(self, weights: Iterable[tuple[str, torch.Tensor]]) -> set[str]:
        stacked_params_mapping = [
            # (param_name, shard_name, shard_id)
            ("merged_linear", "gate_proj", 0),
            ("merged_linear", "up_proj", 1),
        ]
        params_dict = dict(self.named_parameters())
        loaded_params: set[str] = set()

        for name, loaded_weight in weights:
            for param_name, weight_name, shard_id in stacked_params_mapping:
                if weight_name not in name:
                    continue
                name = name.replace(weight_name, param_name)
                # Skip loading extra bias for GPTQ models.
                if name.endswith(".bias") and name not in params_dict:
                    continue
                if is_pp_missing_parameter(name, self):
                    continue
                param = params_dict[name]
                weight_loader = param.weight_loader
                weight_loader(param, loaded_weight, shard_id)
                break
            else:
                if name.endswith(".bias") and name not in params_dict:
                    continue
                if is_pp_missing_parameter(name, self):
                    continue
                param = params_dict[name]
                weight_loader = getattr(param, "weight_loader", default_weight_loader)
                weight_loader(param, loaded_weight)
            loaded_params.add(name)
        return loaded_params


@support_torch_compile
class MolmoModel(nn.Module, SupportsQuant):
    def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
        super().__init__()

        config = vllm_config.model_config.hf_config
        cache_config = vllm_config.cache_config
        quant_config = vllm_config.quant_config

        self.config = config

        self.embedding_size = config.embedding_size or config.vocab_size
        self.embedding_size += ADDITIONAL_VOCAB_SIZE
        self.embed_tokens = VocabParallelEmbedding(
            self.embedding_size,
            config.hidden_size,
            quant_config=quant_config,
        )

        decoder_layer = (
            MolmoDecoderNormAfterLayer if config.norm_after else MolmoDecoderLayer
        )
        self.start_layer, self.end_layer, self.layers = make_layers(
            config.num_hidden_layers,
            lambda prefix: decoder_layer(
                config, cache_config, quant_config, prefix=prefix
            ),
            prefix=f"{prefix}.layers",
        )

        assert config.layer_norm_type == "rms"
        self.norm = RMSNorm(config.hidden_size, config.layer_norm_eps)

        self.make_empty_intermediate_tensors = make_empty_intermediate_tensors_factory(
            ["hidden_states", "residual"], config.hidden_size
        )

    def embed_input_ids(self, input_ids: torch.Tensor) -> torch.Tensor:
        return self.embed_tokens(input_ids)

    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
        intermediate_tensors: IntermediateTensors | None = None,
        inputs_embeds: torch.Tensor | None = None,
    ) -> torch.Tensor:
        if get_pp_group().is_first_rank:
            if inputs_embeds is not None:
                hidden_states = inputs_embeds
            else:
                hidden_states = self.embed_tokens(input_ids)
            residual = None
        else:
            assert intermediate_tensors is not None
            hidden_states = intermediate_tensors["hidden_states"]
            residual = intermediate_tensors["residual"]

        # Apply blocks one-by-one.
        for layer in islice(self.layers, self.start_layer, self.end_layer):
            hidden_states, residual = layer(
                positions,
                hidden_states,
                residual,
            )
        if not get_pp_group().is_last_rank:
            return IntermediateTensors(
                {"hidden_states": hidden_states, "residual": residual}
            )
        if residual is not None:
            hidden_states, _ = self.norm(hidden_states, residual)
        else:
            hidden_states = self.norm(hidden_states)
        return hidden_states

    def load_weights(self, weights: Iterable[tuple[str, torch.Tensor]]) -> set[str]:
        params_dict = dict(self.named_parameters())
        loaded_params: set[str] = set()

        for name, loaded_weight in weights:
            if name.endswith(".bias") and name not in params_dict:
                continue
            if is_pp_missing_parameter(name, self):
                continue

            param = params_dict[name]
            weight_loader = getattr(param, "weight_loader", default_weight_loader)
            weight_loader(param, loaded_weight)
            loaded_params.add(name)
        return loaded_params


def _lowest_multiple(x: int, k: int) -> int:
    return (x // k) * k


def get_num_patches(
    num_tiles: int,
    *,
    crop_patches: int,
    left_margin: int,
    right_margin: int,
    pooling_size: int,
) -> int:
    if num_tiles == 1:
        return _lowest_multiple(crop_patches + pooling_size - 1, pooling_size)

    crop_window_patches = crop_patches - (left_margin + right_margin)

    left_num = _lowest_multiple(
        crop_window_patches + left_margin + pooling_size - 1,
        pooling_size,
    )
    middle_num = _lowest_multiple(
        crop_window_patches + pooling_size - 1,
        pooling_size,
    )
    right_num = _lowest_multiple(
        crop_window_patches + right_margin + pooling_size - 1,
        pooling_size,
    )

    return left_num + (num_tiles - 2) * middle_num + right_num


def get_patches_grid_size(
    *,
    tiling_h: int,
    tiling_w: int,
    crop_patches: int,
    left_margin: int,
    right_margin: int,
    pooling_size: int,
) -> tuple[int, int]:
    nrows = get_num_patches(
        tiling_h,
        crop_patches=crop_patches,
        left_margin=left_margin,
        right_margin=right_margin,
        pooling_size=pooling_size,
    )
    ncols = get_num_patches(
        tiling_w,
        crop_patches=crop_patches,
        left_margin=left_margin,
        right_margin=right_margin,
        pooling_size=pooling_size,
    )

    return nrows, ncols


def get_candidate_tilings(max_num: int) -> list[tuple[int, int]]:
    tilings = [
        (i, j)
        for i in range(1, max_num + 1)
        for j in range(1, max_num + 1)
        if i * j <= max_num
    ]
    return sorted(tilings, key=lambda x: x[0] * x[1])


def select_tiling(
    *,
    height: int,
    width: int,
    patch_size: int,
    max_num_patches: int,
):
    tilings = get_candidate_tilings(max_num_patches)
    candidate_tilings = np.array(tilings, dtype=np.int32)
    candidate_resolutions = candidate_tilings * patch_size

    original_size = np.array([height, width], dtype=np.float32)
    required_scale_d = candidate_resolutions.astype(np.float32) / original_size
    required_scale = required_scale_d.min(axis=-1, keepdims=True)

    if (required_scale < 1).all():
        ix = required_scale.argmax()
    else:
        ix = np.where(required_scale < 1.0, 10e9, required_scale).argmin()

    return candidate_tilings[ix]


class MolmoProcessorWrapper:
    """
    Wraps `MolmoProcessor` so that it can be called directly.

    The original definition can be found here:
    https://huggingface.co/allenai/Molmo-7B-D-0924/blob/main/preprocessing_molmo.py
    """

    def __init__(self, processor: ProcessorMixin):
        super().__init__()

        self.processor = processor

    @cached_property
    def vocab(self) -> dict[str, int]:
        return self.processor.tokenizer.vocab  # type: ignore

    @cached_property
    def max_crops(self) -> int:
        image_processor = self.processor.image_processor  # type: ignore

        max_crops = image_processor.max_crops
        assert isinstance(max_crops, int)

        return max_crops

    @cached_property
    def base_image_input_size(self) -> tuple[int, int]:
        image_processor = self.processor.image_processor  # type: ignore

        base_image_input_size = image_processor.base_image_input_size
        if isinstance(base_image_input_size, int):
            return base_image_input_size, base_image_input_size

        return tuple(base_image_input_size)

    @cached_property
    def image_patch_size(self) -> int:
        image_processor = self.processor.image_processor  # type: ignore

        image_patch_size = image_processor.image_patch_size
        assert isinstance(image_patch_size, int)

        return image_patch_size

    @cached_property
    def overlap_margins(self) -> tuple[int, int]:
        image_processor = self.processor.image_processor  # type: ignore

        left_margin, right_margin = image_processor.overlap_margins
        assert isinstance(left_margin, int)
        assert isinstance(right_margin, int)

        return left_margin, right_margin

    @cached_property
    def image_token_length_w(self) -> int:
        image_processor = self.processor.image_processor  # type: ignore

        image_token_length_w = image_processor.image_token_length_w
        assert isinstance(image_token_length_w, int)

        return image_token_length_w

    @cached_property
    def image_token_length_h(self) -> int:
        image_processor = self.processor.image_processor  # type: ignore

        image_token_length_h = image_processor.image_token_length_h
        assert isinstance(image_token_length_h, int)

        return image_token_length_h

    @property
    def message_format(self) -> str | None:
        return "role"

    @property
    def always_start_with_space(self) -> bool:
        return True

    @cached_property
    def image_patch_id(self) -> int:
        return self.vocab[IMAGE_PATCH_TOKEN]

    @cached_property
    def im_col_id(self) -> int:
        return self.vocab[IM_COL_TOKEN]

    @cached_property
    def im_start_id(self) -> int:
        return self.vocab[IM_START_TOKEN]

    @cached_property
    def im_end_id(self) -> int:
        return self.vocab[IM_END_TOKEN]

    @property
    def pooling_size(self) -> int:
        return POOLING_SIZE

    def select_tiling(
        self,
        *,
        image_width: int,
        image_height: int,
    ) -> tuple[int, int]:
        max_crops = self.max_crops
        left_margin, right_margin = self.overlap_margins
        base_image_input_size = self.base_image_input_size
        base_image_input_d = self.image_patch_size

        total_margin_pixels = base_image_input_d * (right_margin + left_margin)
        crop_patches = base_image_input_size[0] // base_image_input_d
        crop_window_patches = crop_patches - (right_margin + left_margin)
        crop_window_size = crop_window_patches * base_image_input_d
        tiling_h, tiling_w = select_tiling(
            height=image_height - total_margin_pixels,
            width=image_width - total_margin_pixels,
            patch_size=crop_window_size,
            max_num_patches=max_crops,
        )

        return tiling_w, tiling_h

    def get_patches_grid_size(
        self,
        *,
        image_width: int,
        image_height: int,
    ) -> tuple[int, int]:
        left_margin, right_margin = self.overlap_margins
        base_image_input_size = self.base_image_input_size
        base_image_input_d = self.image_patch_size
        pooling_size = self.pooling_size

        crop_patches = base_image_input_size[0] // base_image_input_d
        tiling_w, tiling_h = self.select_tiling(
            image_height=image_height,
            image_width=image_width,
        )

        nrows, ncols = get_patches_grid_size(
            tiling_h=tiling_h,
            tiling_w=tiling_w,
            crop_patches=crop_patches,
            left_margin=left_margin,
            right_margin=right_margin,
            pooling_size=pooling_size,
        )

        return ncols, nrows

    def __call__(
        self,
        text: TextInput | list[TextInput] | None = None,
        images: ImageInput | list[ImageInput] | None = None,
        return_tensors: str | TensorType | None = None,
        **kwargs,
    ) -> BatchFeature:
        outputs = self.processor.process(  # type: ignore
            text, images, **kwargs
        )

        if images is None:
            images = []
        if not isinstance(images, list):
            images = [images]

        input_ids: torch.Tensor = outputs.pop("input_ids")
        outputs["input_ids"] = input_ids.unsqueeze(0)

        image_input_idx = outputs.pop("image_input_idx", None)
        if image_input_idx is not None:
            feat_is_patch = image_input_idx >= 0

            tilings = [
                self.select_tiling(
                    image_width=image.size[0],
                    image_height=image.size[1],
                )
                for image in images
            ]
            # For each image: tiling_h * tiling_w + extra
            num_crops = torch.tensor(tilings).prod(-1) + 1
            assert num_crops.sum() == len(feat_is_patch)

            outputs["image_input_idx"] = image_input_idx
            outputs["num_crops"] = num_crops
            outputs["img_patch_id"] = self.image_patch_id

        return BatchFeature(outputs)


class MolmoProcessingInfo(BaseProcessingInfo):
    def get_hf_processor(self, **kwargs: object) -> MolmoProcessorWrapper:
        processor = self.ctx.get_hf_processor(**kwargs)
        return MolmoProcessorWrapper(processor)

    def get_supported_mm_limits(self) -> Mapping[str, int | None]:
        return {"image": None}

    def get_num_image_tokens(
        self,
        *,
        image_width: int,
        image_height: int,
        processor: MolmoProcessorWrapper | None,
    ) -> int:
        if processor is None:
            processor = self.get_hf_processor()

        ncols, nrows = processor.get_patches_grid_size(
            image_width=image_width,
            image_height=image_height,
        )
        pooling_size = processor.pooling_size

        image_token_length_w = processor.image_token_length_w
        image_token_length_h = processor.image_token_length_h

        # Calculate total tokens: 2 for start/end + (w+1)*h for column separators
        extra = 2 + (image_token_length_w + 1) * image_token_length_h
        joint = 2 + ((ncols + 1) // pooling_size + 1) * ((nrows + 1) // pooling_size)

        return extra + joint

    def get_image_size_with_most_features(self) -> ImageSize:
        processor = self.get_hf_processor()

        tilings = get_candidate_tilings(processor.max_crops)
        base_h, base_w = processor.base_image_input_size

        largest_feature_size, largest_feature_pinpoint = 0, None
        for wr, hr in tilings:
            width, height = base_w * wr, base_h * hr

            feat_size = self.get_num_image_tokens(
                image_width=width,
                image_height=height,
                processor=processor,
            )
            if feat_size > largest_feature_size:
                largest_feature_size = feat_size
                largest_feature_pinpoint = ImageSize(width=width, height=height)

        if largest_feature_size == 0 or largest_feature_pinpoint is None:
            raise ValueError("Cannot have a largest feature size of 0!")

        return largest_feature_pinpoint


class MolmoDummyInputsBuilder(BaseDummyInputsBuilder[MolmoProcessingInfo]):
    def get_dummy_text(self, mm_counts: Mapping[str, int]) -> str:
        return ""

    def get_dummy_mm_data(
        self,
        seq_len: int,
        mm_counts: Mapping[str, int],
        mm_options: Mapping[str, BaseDummyOptions] | None = None,
    ) -> MultiModalDataDict:
        target_width, target_height = self.info.get_image_size_with_most_features()
        num_images = mm_counts.get("image", 0)

        image_overrides = mm_options.get("image") if mm_options else None

        return {
            "image": self._get_dummy_images(
                width=target_width,
                height=target_height,
                num_images=num_images,
                overrides=image_overrides,
            )
        }


class MolmoMultiModalProcessor(BaseMultiModalProcessor[MolmoProcessingInfo]):
    def _apply_hf_processor_tokens_only(
        self,
        prompt_tokens: list[int],
    ) -> list[int]:
        processor = self.info.get_hf_processor()

        # The chat template is already applied to the prompt tokens
        # Use message_format="none" to avoid applying it again
        # Prepend an empty space if `always_start_with_space` is True
        tokens = processor.processor.get_tokens_input(  # type: ignore
            self.info.get_tokenizer().decode(prompt_tokens),
            message_format="none",
            always_start_with_space=processor.always_start_with_space,
        )

        # Prepend a BOS token id to the tokens
        processed_data = self.info.ctx.call_hf_processor(
            processor,  # type: ignore
            dict(tokens=tokens),
        )
        (prompt_ids,) = processed_data.pop("input_ids").tolist()

        return prompt_ids

    def _get_mm_fields_config(
        self,
        hf_inputs: BatchFeature,
        hf_processor_mm_kwargs: Mapping[str, object],
    ) -> Mapping[str, MultiModalFieldConfig]:
        num_crops = hf_inputs.get("num_crops", torch.empty(0))
        num_images = len(num_crops)

        return dict(
            images=MultiModalFieldConfig.flat_from_sizes("image", num_crops),
            image_masks=MultiModalFieldConfig.flat_from_sizes("image", num_crops),
            image_input_idx=MultiModalFieldConfig.flat_from_sizes("image", num_crops),
            num_crops=MultiModalFieldConfig.batched("image"),
            img_patch_id=MultiModalFieldConfig.shared("image", num_images),
        )

    def _get_prompt_updates(
        self,
        mm_items: MultiModalDataItems,
        hf_processor_mm_kwargs: Mapping[str, object],
        out_mm_kwargs: MultiModalKwargsItems,
    ) -> Sequence[PromptUpdate]:
        processor = self.info.get_hf_processor(**hf_processor_mm_kwargs)

        image_token_length_w = processor.image_token_length_w
        image_token_length_h = processor.image_token_length_h
        pooling_size = processor.pooling_size

        img_patch_id = processor.image_patch_id
        img_col_id = processor.im_col_id
        img_start_id = processor.im_start_id
        img_end_id = processor.im_end_id

        extra_row = [img_patch_id] * image_token_length_w + [img_col_id]
        extra_joint = [img_start_id] + extra_row * image_token_length_h + [img_end_id]

        def get_insertion_molmo(item_idx: int):
            images = mm_items.get_items("image", ImageProcessorItems)
            image_size = images.get_image_size(item_idx)

            ncols, nrows = processor.get_patches_grid_size(
                image_width=image_size.width,
                image_height=image_size.height,
            )

            joint_row = [img_patch_id] * ((ncols + 1) // pooling_size) + [img_col_id]
            joint = (
                [img_start_id]
                + joint_row * ((nrows + 1) // pooling_size)
                + [img_end_id]
            )

            return PromptUpdateDetails.select_token_id(
                extra_joint + joint,
                embed_token_id=img_patch_id,
            )

        return [
            PromptInsertion(
                modality="image",
                target=PromptIndexTargets.prefix("<|endoftext|>"),
                insertion=get_insertion_molmo,
            )
        ]


@MULTIMODAL_REGISTRY.register_processor(
    MolmoMultiModalProcessor,
    info=MolmoProcessingInfo,
    dummy_inputs=MolmoDummyInputsBuilder,
)
class MolmoForCausalLM(
    nn.Module, SupportsMultiModal, SupportsPP, SupportsLoRA, SupportsQuant
):
    merge_by_field_config = True

    hf_to_vllm_mapper = WeightsMapper(
        orig_to_new_substr={
            # vision backbone mapping
            "image_projector.w1.": "image_projector.gate_proj.",
            "image_projector.w3.": "image_projector.up_proj.",
            "image_projector.w2.": "image_projector.down_proj.",
            # language backbone mapping
            "att_proj": "self_attn.qkv_proj",
            "attn_out": "self_attn.o_proj",
            "q_norm": "self_attn.q_norm",
            "k_norm": "self_attn.k_norm",
            "ff_proj": "mlp.gate_up_proj",
            "ff_out": "mlp.down_proj",
            "attn_norm": "input_layernorm",
            "ff_norm": "post_attention_layernorm",
        },
        orig_to_new_prefix={
            # vision backbone mapping
            "model.vision_backbone.": "vision_backbone.",
            # language backbone mapping
            "model.transformer.blocks.": "model.layers.",
            "model.transformer.ln_f.": "model.norm.",
            # lm_head is renamed to model.transformer.mlp.down_proj firstly,
            # we need to run a second renaming for it
            "model.transformer.mlp.down_proj.": "lm_head.",
        },
    )

    packed_modules_mapping = {
        "qkv_proj": ["qkv_proj"],
        "gate_up_proj": ["gate_up_proj"],  # language model
        "merged_linear": ["gate_proj", "up_proj"],  # image_projector
    }

    @classmethod
    def get_placeholder_str(cls, modality: str, i: int) -> str | None:
        if modality.startswith("image"):
            return None

        raise ValueError("Only image modality is supported")

    def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
        super().__init__()
        config = vllm_config.model_config.hf_config
        quant_config = vllm_config.quant_config
        multimodal_config = vllm_config.model_config.multimodal_config

        self.config = config
        self.multimodal_config = multimodal_config

        vision_config = VisionBackboneConfig()
        self.vision_backbone = MolmoVisionBackbone(config, vision_config, quant_config)
        self.model = MolmoModel(
            vllm_config=vllm_config, prefix=maybe_prefix(prefix, "model")
        )
        self.img_patch_id = None

        if self.config.weight_tying:
            self.lm_head = self.model.transformer.wte
        else:
            self.lm_head = ParallelLMHead(
                config.embedding_size or config.vocab_size,
                config.hidden_size,
                quant_config=quant_config,
                prefix=maybe_prefix(prefix, "lm_head"),
            )

        self.logits_processor = LogitsProcessor(
            config.embedding_size or config.vocab_size
        )

        self.make_empty_intermediate_tensors = (
            self.model.make_empty_intermediate_tensors
        )

    def _parse_and_validate_image_input(
        self,
        **kwargs: object,
    ) -> MolmoImageInputs | None:
        images = kwargs.pop("images", None)
        image_masks = kwargs.pop("image_masks", None)
        image_input_idx = kwargs.pop("image_input_idx", None)
        num_crops = kwargs.pop("num_crops", None)

        if images is None:
            return None

        img_patch_id = kwargs.pop("img_patch_id", None)
        if isinstance(img_patch_id, torch.Tensor):
            img_patch_id = img_patch_id.item()

        assert isinstance(img_patch_id, int)
        self.img_patch_id = img_patch_id

        return MolmoImageInputs(
            images=images,
            image_masks=image_masks,
            image_input_idx=image_input_idx,
            num_crops=num_crops,
        )

    def _process_image_input(
        self,
        image_input: MolmoImageInputs,
    ) -> list[torch.Tensor]:
        images = image_input["images"]
        image_masks = image_input["image_masks"]
        image_input_idx = image_input["image_input_idx"]
        num_crops = image_input["num_crops"]

        # Call the vision backbone on the whole batch at once
        image_features = self.vision_backbone(
            images=images.unsqueeze(0),
            image_masks=None if image_masks is None else image_masks.unsqueeze(0),
        ).squeeze(0)

        # Only the features corresponding to patch tokens are relevant
        # Re-order the features using the image_input_idx tensor
        results = []
        num_crops_list = num_crops.tolist()
        for feats, img_idx in zip(
            image_features.split(num_crops_list),
            image_input_idx.split(num_crops_list),
        ):
            is_valid = img_idx >= 0
            valid_img_idx = img_idx[is_valid]
            order = torch.argsort(valid_img_idx)
            results.append(feats[is_valid][order])
        return results

    def get_language_model(self) -> torch.nn.Module:
        return self.model

    def embed_multimodal(self, **kwargs: object) -> MultiModalEmbeddings:
        image_input = self._parse_and_validate_image_input(**kwargs)
        if image_input is None:
            return []

        return self._process_image_input(image_input)

    def forward(
        self,
        input_ids: torch.LongTensor,
        positions: torch.LongTensor,
        intermediate_tensors: IntermediateTensors | None = None,
        inputs_embeds: torch.Tensor | None = None,
        **kwargs: object,
    ) -> torch.Tensor:
        if intermediate_tensors is not None:
            inputs_embeds = None

        hidden_states = self.model(
            input_ids, positions, intermediate_tensors, inputs_embeds=inputs_embeds
        )

        return hidden_states

    def compute_logits(self, hidden_states: torch.Tensor) -> torch.Tensor:
        logits = self.logits_processor(self.lm_head, hidden_states)
        return logits

    def load_weights(self, weights: Iterable[tuple[str, torch.Tensor]]):
        loader = AutoWeightsLoader(self)
        weights = _get_weights_with_merged_embedding(weights)
        return loader.load_weights(weights, mapper=self.hf_to_vllm_mapper)

    def get_mm_mapping(self) -> MultiModelKeys:
        """
        Get the module prefix in multimodal models
        """
        return MultiModelKeys.from_string_field(
            language_model="model",
            connector="vision_backbone.image_projector",
            tower_model="vision_backbone",
        )


def _get_weights_with_merged_embedding(
    weights: Iterable[tuple[str, torch.Tensor]],
) -> Iterable[tuple[str, torch.Tensor]]:
    embedding_weights = {}
    for name, weight in weights:
        if "wte.embedding" in name:
            embedding_weights["embedding"] = weight
        elif "wte.new_embedding" in name:
            embedding_weights["new_embedding"] = weight
        else:
            yield (name, weight)
    # this is compatible with most of quantization,
    # because they won't quantize embed_tokens
    embedding_weights = torch.cat(
        [embedding_weights["embedding"], embedding_weights["new_embedding"]],
        dim=0,
    )
    yield ("model.embed_tokens.weight", embedding_weights)