MobileLLM-Pro / modeling_mobilellm_p1.py
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import math
from dataclasses import dataclass
from typing import Callable, Optional, Union
import copy
import torch
import torch.nn as nn
import torch.nn.functional as F
from transformers.activations import ACT2FN
from transformers.cache_utils import Cache, DynamicCache
from transformers.generation import GenerationMixin
from transformers.integrations import use_kernel_forward_from_hub
from transformers.masking_utils import (
create_causal_mask,
create_sliding_window_causal_mask,
)
from transformers.modeling_flash_attention_utils import FlashAttentionKwargs
from transformers.modeling_layers import GradientCheckpointingLayer
from transformers.modeling_outputs import (
BaseModelOutput,
BaseModelOutputWithPast,
CausalLMOutputWithPast,
ModelOutput,
)
from transformers.modeling_rope_utils import dynamic_rope_update, ROPE_INIT_FUNCTIONS
from transformers.modeling_utils import ALL_ATTENTION_FUNCTIONS, PreTrainedModel
from transformers.models.llama4.configuration_llama4 import (
Llama4Config,
Llama4TextConfig,
Llama4VisionConfig,
)
from transformers.models.llama4.modeling_llama4 import (
apply_rotary_emb,
eager_attention_forward,
Llama4PreTrainedModel,
Llama4TextDecoderLayer,
Llama4TextL2Norm,
Llama4TextMLP,
Llama4TextMoe,
Llama4TextRMSNorm,
Llama4TextRotaryEmbedding,
Llama4TextAttention,
Llama4TextDecoderLayer,
Llama4ForCausalLM
)
from transformers.processing_utils import Unpack
from transformers.utils import (
auto_docstring,
can_return_tuple,
logging,
TransformersKwargs,
)
from transformers.utils.deprecation import deprecate_kwarg
from transformers.utils.generic import check_model_inputs
from .configuration_mobilellm_p1 import MobileLLMP1TextConfig
logger = logging.get_logger(__name__)
class MobileLLMP1TextAttention(nn.Module):
"""Multi-headed attention from 'Attention Is All You Need' paper"""
def __init__(self, config: MobileLLMP1TextConfig, layer_idx):
super().__init__()
self.config = config
self.layer_idx = layer_idx
self.is_sliding = config.layer_types[layer_idx] == "sliding_attention"
self.head_dim = getattr(
config, "head_dim", config.hidden_size // config.num_attention_heads
)
self.num_attention_heads = config.num_attention_heads
self.num_key_value_groups = (
config.num_attention_heads // config.num_key_value_heads
)
self.num_key_value_heads = config.num_key_value_heads
self.scaling = self.head_dim**-0.5
self.attn_scale = config.attn_scale
self.floor_scale = config.floor_scale
self.attn_temperature_tuning = config.attn_temperature_tuning
self.attention_dropout = config.attention_dropout
self.is_causal = True
self.use_rope = config.no_rope_layers[layer_idx]
self.sliding_window = config.sliding_window if self.is_sliding else None
self.q_proj = nn.Linear(
config.hidden_size,
config.num_attention_heads * self.head_dim,
bias=config.attention_bias,
)
self.k_proj = nn.Linear(
config.hidden_size,
config.num_key_value_heads * self.head_dim,
bias=config.attention_bias,
)
self.v_proj = nn.Linear(
config.hidden_size,
config.num_key_value_heads * self.head_dim,
bias=config.attention_bias,
)
self.o_proj = nn.Linear(
config.num_attention_heads * self.head_dim,
config.hidden_size,
bias=config.attention_bias,
)
if self.config.use_qk_norm and self.use_rope:
self.qk_norm = Llama4TextL2Norm(config.rms_norm_eps)
def forward(
self,
hidden_states: torch.Tensor,
position_embeddings: tuple[torch.Tensor, torch.Tensor],
attention_mask: Optional[torch.Tensor],
past_key_values: Optional[Cache] = None,
cache_position: Optional[torch.LongTensor] = None,
**kwargs: Unpack[FlashAttentionKwargs],
) -> tuple[torch.Tensor, Optional[torch.Tensor], Optional[tuple[torch.Tensor]]]:
input_shape = hidden_states.shape[:-1]
hidden_shape = (*input_shape, -1, self.head_dim)
query_states = self.q_proj(hidden_states).view(hidden_shape)
key_states = self.k_proj(hidden_states).view(*input_shape, -1, self.head_dim)
value_states = self.v_proj(hidden_states).view(hidden_shape).transpose(1, 2)
if self.use_rope: # the 16E model skips rope for long context on certain layers
query_states, key_states = apply_rotary_emb(
query_states, key_states, position_embeddings.to(query_states.device)
)
if hasattr(self, "qk_norm"): # the 128E model does not use qk_norm
query_states = self.qk_norm(query_states)
key_states = self.qk_norm(key_states)
# Use temperature tuning from https://huggingface.co/papers/2501.19399) to NoROPE layers
if self.attn_temperature_tuning and not self.use_rope:
attn_scales = (
torch.log(
torch.floor((cache_position.float() + 1.0) / self.floor_scale) + 1.0
)
* self.attn_scale
+ 1.0
)
attn_scales = attn_scales.view((1, input_shape[-1], 1, 1)).expand(
(*input_shape, 1, 1)
) # batch size > 1
query_states = (query_states * attn_scales).to(query_states.dtype)
query_states = query_states.transpose(1, 2)
key_states = key_states.transpose(1, 2)
if past_key_values is not None:
# sin and cos are specific to RoPE models; cache_position needed for the static cache
cache_kwargs = {"cache_position": cache_position}
key_states, value_states = past_key_values.update(
key_states, value_states, self.layer_idx, cache_kwargs
)
attention_interface: Callable = eager_attention_forward
if self.config._attn_implementation != "eager":
attention_interface = ALL_ATTENTION_FUNCTIONS[
self.config._attn_implementation
]
attn_output, attn_weights = attention_interface(
self,
query_states,
key_states,
value_states,
attention_mask,
dropout=0.0 if not self.training else self.attention_dropout,
scaling=self.scaling,
sliding_window=self.sliding_window,
**kwargs,
)
attn_output = attn_output.reshape(*input_shape, -1).contiguous()
attn_output = self.o_proj(attn_output)
return attn_output, attn_weights
class MobileLLMP1TextDecoderLayer(GradientCheckpointingLayer):
def __init__(self, config, layer_idx):
super().__init__()
self.hidden_size = config.hidden_size
self.layer_idx = layer_idx
self.attention_type = config.layer_types[layer_idx]
self.self_attn = MobileLLMP1TextAttention(config, layer_idx)
self.is_moe_layer = layer_idx in config.moe_layers
if self.is_moe_layer: # the 128E model interleaves dense / sparse
self.feed_forward = Llama4TextMoe(config)
else:
self.feed_forward = Llama4TextMLP(
config, intermediate_size=config.intermediate_size_mlp
)
self.input_layernorm = Llama4TextRMSNorm(
config.hidden_size, eps=config.rms_norm_eps
)
self.post_attention_layernorm = Llama4TextRMSNorm(
config.hidden_size, eps=config.rms_norm_eps
)
def forward(
self,
hidden_states: torch.Tensor,
attention_mask: Optional[torch.Tensor] = None,
position_ids: Optional[torch.LongTensor] = None,
past_key_values: Optional[Cache] = None,
use_cache: Optional[bool] = False,
cache_position: Optional[torch.LongTensor] = None,
position_embeddings: Optional[tuple[torch.Tensor, torch.Tensor]] = None, # necessary, but kept here for BC
**kwargs: Unpack[FlashAttentionKwargs],
) -> tuple[
torch.FloatTensor, Optional[tuple[torch.FloatTensor, torch.FloatTensor]]
]:
residual = hidden_states
hidden_states = self.input_layernorm(hidden_states)
# Self Attention
attention_states, _ = self.self_attn(
hidden_states=hidden_states,
position_embeddings=position_embeddings,
attention_mask=attention_mask,
past_key_values=past_key_values,
use_cache=use_cache,
cache_position=cache_position,
**kwargs,
)
hidden_states = residual + attention_states
# Fully Connected
residual = hidden_states
hidden_states = self.post_attention_layernorm(hidden_states)
hidden_states = self.feed_forward(hidden_states)
if self.is_moe_layer:
hidden_states, _ = hidden_states
hidden_states = residual + hidden_states.view(residual.shape)
return hidden_states
class MobileLLMP1TextModel(Llama4PreTrainedModel):
_no_split_modules = ["MobileLLMP1TextDecoderLayer"]
base_model_prefix = "model"
config: MobileLLMP1TextConfig
_can_record_outputs = {
"attentions": MobileLLMP1TextAttention,
"hidden_states": MobileLLMP1TextDecoderLayer,
"router_logits": Llama4TextMoe,
}
def __init__(self, config: MobileLLMP1TextConfig):
super().__init__(config)
self.padding_idx = config.pad_token_id
self.vocab_size = config.vocab_size
self.embed_tokens = nn.Embedding(
config.vocab_size, config.hidden_size, self.padding_idx
)
self.layers = nn.ModuleList(
[
MobileLLMP1TextDecoderLayer(config, layer_idx)
for layer_idx in range(config.num_hidden_layers)
]
)
self.norm = Llama4TextRMSNorm(config.hidden_size, eps=config.rms_norm_eps)
self.rotary_emb = Llama4TextRotaryEmbedding(config=config)
self.gradient_checkpointing = False
# Initialize weights and apply final processing
self.post_init()
def forward(
self,
input_ids: Optional[torch.LongTensor] = None,
attention_mask: Optional[torch.Tensor] = None,
position_ids: Optional[torch.LongTensor] = None,
past_key_values: Optional[Cache] = None,
inputs_embeds: Optional[torch.FloatTensor] = None,
use_cache: Optional[bool] = None,
cache_position: Optional[torch.LongTensor] = None,
**kwargs: Unpack[TransformersKwargs],
) -> Union[tuple, BaseModelOutputWithPast]:
if (input_ids is None) ^ (inputs_embeds is not None):
raise ValueError(
"You must specify exactly one of input_ids or inputs_embeds"
)
if inputs_embeds is None:
inputs_embeds = self.embed_tokens(
input_ids.to(self.embed_tokens.weight.device)
)
if use_cache and past_key_values is None:
past_key_values = DynamicCache(config=self.config)
if cache_position is None:
past_seen_tokens = (
past_key_values.get_seq_length() if past_key_values is not None else 0
)
cache_position = torch.arange(
past_seen_tokens,
past_seen_tokens + inputs_embeds.shape[1],
device=inputs_embeds.device,
)
if position_ids is None:
position_ids = cache_position.unsqueeze(0)
# It may already have been prepared by e.g. `generate`
if not isinstance(causal_mask_mapping := attention_mask, dict):
# Prepare mask arguments
mask_kwargs = {
"config": self.config,
"input_embeds": inputs_embeds,
"attention_mask": attention_mask,
"cache_position": cache_position,
"past_key_values": past_key_values,
"position_ids": position_ids,
}
sliding_mask_kwargs = mask_kwargs.copy()
del sliding_mask_kwargs['position_ids']
# Create the masks
causal_mask_mapping = {
"full_attention": create_causal_mask(**mask_kwargs),
"sliding_attention": create_sliding_window_causal_mask(
**sliding_mask_kwargs
),
}
hidden_states = inputs_embeds
# create position embeddings to be shared across the decoder layers
freq_cis = self.rotary_emb(hidden_states, position_ids)
# found = False
for decoder_layer in self.layers[: self.config.num_hidden_layers]:
hidden_states = decoder_layer(
hidden_states,
attention_mask=causal_mask_mapping[decoder_layer.attention_type],
position_ids=position_ids,
past_key_values=past_key_values,
use_cache=use_cache,
cache_position=cache_position,
position_embeddings=freq_cis,
**kwargs,
)
hidden_states = self.norm(hidden_states)
return BaseModelOutputWithPast(
last_hidden_state=hidden_states,
past_key_values=past_key_values if use_cache else None,
)
class MobileLLMP1ForCausalLM(Llama4PreTrainedModel, GenerationMixin):
_no_split_modules = ["MobileLLMP1TextDecoderLayer"]
base_model_prefix = "language_model"
_tied_weights_keys = ["lm_head.weight"]
_tp_plan = {"lm_head": "colwise_rep"}
config: MobileLLMP1TextConfig
def __init__(self, config: MobileLLMP1TextConfig):
super().__init__(config)
self.model = MobileLLMP1TextModel(config)
self.vocab_size = config.vocab_size
self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)
# Initialize weights and apply final processing
self.post_init()
def forward(
self,
input_ids: Optional[torch.LongTensor] = None,
attention_mask: Optional[torch.Tensor] = None,
position_ids: Optional[torch.LongTensor] = None,
past_key_values: Optional[Union[Cache, list[torch.FloatTensor]]] = None,
inputs_embeds: Optional[torch.FloatTensor] = None,
labels: Optional[torch.LongTensor] = None,
use_cache: Optional[bool] = None,
cache_position: Optional[torch.LongTensor] = None,
logits_to_keep: Union[int, torch.Tensor] = 0,
**kwargs: Unpack[TransformersKwargs],
) -> Union[tuple, CausalLMOutputWithPast]:
r"""
labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
Labels for computing the masked language modeling loss. Indices should either be in `[0, ...,
config.vocab_size]` or -100 (see `input_ids` docstring). Tokens with indices set to `-100` are ignored
(masked), the loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]`.
Example:
```python
>>> from transformers import AutoTokenizer, Llama4ForCausalLM
>>> model = Llama4ForCausalLM.from_pretrained("meta-llama4/Llama4-2-7b-hf")
>>> tokenizer = AutoTokenizer.from_pretrained("meta-llama4/Llama4-2-7b-hf")
>>> prompt = "Hey, are you conscious? Can you talk to me?"
>>> inputs = tokenizer(prompt, return_tensors="pt")
>>> # Generate
>>> generate_ids = model.generate(inputs.input_ids, max_length=30)
>>> tokenizer.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
"Hey, are you conscious? Can you talk to me?\nI'm not conscious, but I can talk to you."
```"""
outputs = self.model(
input_ids=input_ids,
attention_mask=attention_mask,
position_ids=position_ids,
past_key_values=past_key_values,
inputs_embeds=inputs_embeds,
use_cache=use_cache,
cache_position=cache_position,
**kwargs,
)
hidden_states = outputs[0]
# Only compute necessary logixts, and do not upcast them to float if we are not computing the loss
slice_indices = (
slice(-logits_to_keep, None)
if isinstance(logits_to_keep, int)
else logits_to_keep
)
logits = self.lm_head(hidden_states[:, slice_indices, :])
loss = None
if labels is not None:
loss = self.loss_function(
logits=logits,
labels=labels,
vocab_size=self.config.vocab_size,
**kwargs,
)
return CausalLMOutputWithPast(
loss=loss,
logits=logits,
past_key_values=outputs.past_key_values,
hidden_states=outputs.hidden_states,
attentions=outputs.attentions,
)
__all__ = [
"MobileLLMP1ForCausalLM",
"MobileLLMP1TextModel",
"MobileLLMP1TextDecoderLayer",
"MobileLLMP1TextAttention",
]