gemma-3-270m-it-p2.8 / modeling_gemma3.py
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# This file was automatically generated from src/transformers/models/gemma3/modular_gemma3.py.
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# Copyright 2025 Google Inc. HuggingFace Inc. 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 collections.abc import Callable
from dataclasses import dataclass
from typing import Optional
import torch
import torch.nn as nn
import torch.nn.functional as F
from transformers import initialization as init
from transformers.activations import ACT2FN
from transformers.cache_utils import Cache, DynamicCache
from transformers.configuration_utils import PreTrainedConfig
from transformers.generation import GenerationMixin
from transformers.integrations import use_kernel_func_from_hub, use_kernelized_func
from transformers.masking_utils import create_causal_mask, create_masks_for_generate, create_sliding_window_causal_mask
from transformers.modeling_layers import GenericForSequenceClassification, GradientCheckpointingLayer
from transformers.modeling_outputs import (
BaseModelOutputWithPast,
BaseModelOutputWithPooling,
CausalLMOutputWithPast,
SequenceClassifierOutputWithPast,
)
from transformers.modeling_rope_utils import ROPE_INIT_FUNCTIONS, dynamic_rope_update
from transformers.modeling_utils import ALL_ATTENTION_FUNCTIONS, PreTrainedModel
from transformers.processing_utils import Unpack
from transformers.utils import ModelOutput, TransformersKwargs, auto_docstring, can_return_tuple, torch_compilable_check
from transformers.utils.generic import maybe_autocast, merge_with_config_defaults
from transformers.utils.output_capturing import capture_outputs
from transformers import AutoModel
from configuration_gemma3 import Gemma3Config, Gemma3TextConfig
from p28_modules import LTIInjection, StabilityMonitor, ReadOnlyCache
@auto_docstring(
custom_intro="""
Base class for Gemma3 outputs, with hidden states and attentions.
"""
)
@dataclass
class Gemma3ModelOutputWithPast(BaseModelOutputWithPast):
r"""
image_hidden_states (`torch.FloatTensor`, *optional*):
A `torch.FloatTensor` of size `(batch_size, num_images, sequence_length, hidden_size)`.
image_hidden_states of the model produced by the vision encoder and after projecting the last hidden state.
"""
image_hidden_states: torch.FloatTensor | None = None
@auto_docstring(
custom_intro="""
Base class for Gemma3 causal language model (or autoregressive) outputs.
"""
)
@dataclass
class Gemma3CausalLMOutputWithPast(ModelOutput):
r"""
loss (`torch.FloatTensor` of shape `(1,)`, *optional*, returned when `labels` is provided):
Language modeling loss (for next-token prediction).
logits (`torch.FloatTensor` of shape `(batch_size, sequence_length, config.text_config.vocab_size)`):
Prediction scores of the language modeling head (scores for each vocabulary token before SoftMax).
past_key_values (`Cache`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
It is a [`~cache_utils.Cache`] instance. For more details, see our [kv cache guide](https://huggingface.co/docs/transformers/en/kv_cache).
Contains pre-computed hidden-states (key and values in the self-attention blocks) that can be used (see
`past_key_values` input) to speed up sequential decoding.
image_hidden_states (`torch.FloatTensor`, *optional*):
A `torch.FloatTensor` of size `(batch_size, num_images, sequence_length, hidden_size)`.
image_hidden_states of the model produced by the vision encoder after projecting last hidden state.
"""
loss: torch.FloatTensor | None = None
logits: torch.FloatTensor | None = None
past_key_values: Cache | None = None
hidden_states: tuple[torch.FloatTensor] | None = None
attentions: tuple[torch.FloatTensor] | None = None
image_hidden_states: torch.FloatTensor | None = None
class Gemma3TextScaledWordEmbedding(nn.Embedding):
"""
This module overrides nn.Embeddings' forward by multiplying with embeddings scale.
"""
def __init__(self, num_embeddings: int, embedding_dim: int, padding_idx: int, embed_scale: float = 1.0):
super().__init__(num_embeddings, embedding_dim, padding_idx)
self.scalar_embed_scale = embed_scale
self.register_buffer("embed_scale", torch.tensor(embed_scale), persistent=False)
def forward(self, input_ids: torch.Tensor):
return super().forward(input_ids) * self.embed_scale.to(self.weight.dtype)
class Gemma3MLP(nn.Module):
def __init__(self, config: Gemma3TextConfig):
super().__init__()
self.config = config
self.hidden_size = config.hidden_size
self.intermediate_size = config.intermediate_size
self.gate_proj = nn.Linear(self.hidden_size, self.intermediate_size, bias=False)
self.up_proj = nn.Linear(self.hidden_size, self.intermediate_size, bias=False)
self.down_proj = nn.Linear(self.intermediate_size, self.hidden_size, bias=False)
self.act_fn = ACT2FN[config.hidden_activation]
def forward(self, x):
down_proj = self.down_proj(self.act_fn(self.gate_proj(x)) * self.up_proj(x))
return down_proj
class Gemma3RMSNorm(nn.Module):
def __init__(self, dim: int, eps: float = 1e-6):
super().__init__()
self.eps = eps
self.weight = nn.Parameter(torch.zeros(dim))
def _norm(self, x):
return x * torch.rsqrt(x.pow(2).mean(-1, keepdim=True) + self.eps)
def forward(self, x):
output = self._norm(x.float())
# Llama does x.to(float16) * w whilst Gemma3 is (x * w).to(float16)
# See https://github.com/huggingface/transformers/pull/29402
output = output * (1.0 + self.weight.float())
return output.type_as(x)
def extra_repr(self):
return f"{tuple(self.weight.shape)}, eps={self.eps}"
class Gemma3RotaryEmbedding(nn.Module):
inv_freq: torch.Tensor # fix linting for `register_buffer`
def __init__(self, config: Gemma3TextConfig):
super().__init__()
self.max_seq_len_cached = config.max_position_embeddings
self.original_max_seq_len = config.max_position_embeddings
self.config = config
self.layer_types = list(set(config.layer_types))
self.rope_type = {}
for layer_type in self.layer_types:
rope_params = self.config.rope_parameters[layer_type]
if rope_params is None:
continue
self.rope_type[layer_type] = rope_params["rope_type"]
rope_init_fn: Callable = self.compute_default_rope_parameters
if self.rope_type[layer_type] != "default":
rope_init_fn = ROPE_INIT_FUNCTIONS[self.rope_type[layer_type]]
curr_inv_freq, curr_attention_scaling = rope_init_fn(self.config, layer_type=layer_type)
self.register_buffer(f"{layer_type}_inv_freq", curr_inv_freq, persistent=False)
self.register_buffer(f"{layer_type}_original_inv_freq", curr_inv_freq.clone(), persistent=False)
setattr(self, f"{layer_type}_attention_scaling", curr_attention_scaling)
@staticmethod
def compute_default_rope_parameters(
config: Gemma3TextConfig | None = None,
device: Optional["torch.device"] = None,
seq_len: int | None = None,
layer_type: str | None = None,
) -> tuple["torch.Tensor", float]:
"""
Computes the inverse frequencies according to the original RoPE implementation
Args:
config ([`~transformers.PreTrainedConfig`]):
The model configuration.
device (`torch.device`):
The device to use for initialization of the inverse frequencies.
seq_len (`int`, *optional*):
The current sequence length. Unused for this type of RoPE.
layer_type (`str`, *optional*):
The current layer type if the model has different RoPE parameters per type.
Should not be used unless `config.layer_types is not None`
Returns:
Tuple of (`torch.Tensor`, `float`), containing the inverse frequencies for the RoPE embeddings and the
post-processing scaling factor applied to the computed cos/sin (unused in this type of RoPE).
"""
# For backward compatibility standardize the `rope_parameters_dict` if it uses old format
base = config.rope_parameters[layer_type]["rope_theta"]
dim = getattr(config, "head_dim", None) or config.hidden_size // config.num_attention_heads
attention_factor = 1.0 # Unused in this type of RoPE
# Compute the inverse frequencies
inv_freq = 1.0 / (
base ** (torch.arange(0, dim, 2, dtype=torch.int64).to(device=device, dtype=torch.float) / dim)
)
return inv_freq, attention_factor
@torch.no_grad()
@dynamic_rope_update # power user: used with advanced RoPE types (e.g. dynamic rope)
def forward(self, x, position_ids, layer_type=None):
inv_freq = getattr(self, f"{layer_type}_inv_freq")
attention_scaling = getattr(self, f"{layer_type}_attention_scaling")
inv_freq_expanded = inv_freq[None, :, None].float().expand(position_ids.shape[0], -1, 1).to(x.device)
position_ids_expanded = position_ids[:, None, :].float()
device_type = x.device.type if isinstance(x.device.type, str) and x.device.type != "mps" else "cpu"
with maybe_autocast(device_type=device_type, enabled=False): # Force float32
freqs = (inv_freq_expanded.float() @ position_ids_expanded.float()).transpose(1, 2)
emb = torch.cat((freqs, freqs), dim=-1)
cos = emb.cos() * attention_scaling
sin = emb.sin() * attention_scaling
return cos.to(dtype=x.dtype), sin.to(dtype=x.dtype)
def rotate_half(x):
"""Rotates half the hidden dims of the input."""
x1 = x[..., : x.shape[-1] // 2]
x2 = x[..., x.shape[-1] // 2 :]
return torch.cat((-x2, x1), dim=-1)
@use_kernel_func_from_hub("rotary_pos_emb")
def apply_rotary_pos_emb(q, k, cos, sin, unsqueeze_dim=1):
"""Applies Rotary Position Embedding to the query and key tensors.
Args:
q (`torch.Tensor`): The query tensor.
k (`torch.Tensor`): The key tensor.
cos (`torch.Tensor`): The cosine part of the rotary embedding.
sin (`torch.Tensor`): The sine part of the rotary embedding.
unsqueeze_dim (`int`, *optional*, defaults to 1):
The 'unsqueeze_dim' argument specifies the dimension along which to unsqueeze cos[position_ids] and
sin[position_ids] so that they can be properly broadcasted to the dimensions of q and k. For example, note
that cos[position_ids] and sin[position_ids] have the shape [batch_size, seq_len, head_dim]. Then, if q and
k have the shape [batch_size, heads, seq_len, head_dim], then setting unsqueeze_dim=1 makes
cos[position_ids] and sin[position_ids] broadcastable to the shapes of q and k. Similarly, if q and k have
the shape [batch_size, seq_len, heads, head_dim], then set unsqueeze_dim=2.
Returns:
`tuple(torch.Tensor)` comprising of the query and key tensors rotated using the Rotary Position Embedding.
"""
cos = cos.unsqueeze(unsqueeze_dim)
sin = sin.unsqueeze(unsqueeze_dim)
q_embed = (q * cos) + (rotate_half(q) * sin)
k_embed = (k * cos) + (rotate_half(k) * sin)
return q_embed, k_embed
def repeat_kv(hidden_states: torch.Tensor, n_rep: int) -> torch.Tensor:
"""
This is the equivalent of torch.repeat_interleave(x, dim=1, repeats=n_rep). The hidden states go from (batch,
num_key_value_heads, seqlen, head_dim) to (batch, num_attention_heads, seqlen, head_dim)
"""
batch, num_key_value_heads, slen, head_dim = hidden_states.shape
if n_rep == 1:
return hidden_states
hidden_states = hidden_states[:, :, None, :, :].expand(batch, num_key_value_heads, n_rep, slen, head_dim)
return hidden_states.reshape(batch, num_key_value_heads * n_rep, slen, head_dim)
def eager_attention_forward(
module: nn.Module,
query: torch.Tensor,
key: torch.Tensor,
value: torch.Tensor,
attention_mask: torch.Tensor | None,
dropout: float | int = 0.0,
scaling: float | None = None,
softcap: float | None = None,
**kwargs,
) -> tuple[torch.Tensor, torch.Tensor]:
if scaling is None:
scaling = module.head_dim**-0.5
key_states = repeat_kv(key, module.num_key_value_groups)
value_states = repeat_kv(value, module.num_key_value_groups)
attn_weights = torch.matmul(query, key_states.transpose(2, 3)) * scaling
if softcap is not None:
attn_weights = attn_weights / softcap
attn_weights = torch.tanh(attn_weights)
attn_weights = attn_weights * softcap
if attention_mask is not None:
attn_weights = attn_weights + attention_mask
# upcast attention to fp32
attn_weights = nn.functional.softmax(attn_weights, dim=-1, dtype=torch.float32).to(query.dtype)
attn_weights = nn.functional.dropout(attn_weights, p=dropout, training=module.training)
attn_output = torch.matmul(attn_weights, value_states)
attn_output = attn_output.transpose(1, 2).contiguous()
return attn_output, attn_weights
@use_kernelized_func(apply_rotary_pos_emb)
class Gemma3Attention(nn.Module):
"""Multi-headed attention from 'Attention Is All You Need' paper"""
def __init__(self, config: Gemma3TextConfig, layer_idx: int):
super().__init__()
self.layer_type = config.layer_types[layer_idx] if hasattr(config, "layer_types") else None
self.config = config
self.layer_idx = layer_idx
self.head_dim = getattr(config, "head_dim", config.hidden_size // config.num_attention_heads)
self.num_key_value_groups = config.num_attention_heads // config.num_key_value_heads
self.scaling = config.query_pre_attn_scalar**-0.5
self.attention_dropout = self.config.attention_dropout
self.is_causal = not self.config.use_bidirectional_attention
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
)
self.attn_logit_softcapping = self.config.attn_logit_softcapping
self.sliding_window = config.sliding_window if self.layer_type == "sliding_attention" else None
self.is_sliding = self.layer_type == "sliding_attention"
self.q_norm = Gemma3RMSNorm(dim=config.head_dim, eps=config.rms_norm_eps)
self.k_norm = Gemma3RMSNorm(dim=config.head_dim, eps=config.rms_norm_eps)
def forward(
self,
hidden_states: torch.Tensor,
position_embeddings: torch.Tensor = None,
attention_mask: torch.Tensor | None = None,
past_key_values: Cache | None = None,
**kwargs: Unpack[TransformersKwargs],
) -> tuple[torch.Tensor, torch.Tensor | None, tuple[torch.Tensor] | None]:
input_shape = hidden_states.shape[:-1]
hidden_shape = (*input_shape, -1, self.head_dim)
query_states = self.q_proj(hidden_states).view(hidden_shape).transpose(1, 2)
key_states = self.k_proj(hidden_states).view(hidden_shape).transpose(1, 2)
value_states = self.v_proj(hidden_states).view(hidden_shape).transpose(1, 2)
query_states = self.q_norm(query_states)
key_states = self.k_norm(key_states)
cos, sin = position_embeddings
query_states, key_states = apply_rotary_pos_emb(query_states, key_states, cos, sin)
if past_key_values is not None:
key_states, value_states = past_key_values.update(key_states, value_states, self.layer_idx)
attention_interface: Callable = ALL_ATTENTION_FUNCTIONS.get_interface(
self.config._attn_implementation, eager_attention_forward
)
attn_output, attn_weights = attention_interface(
self,
query_states,
key_states,
value_states,
attention_mask,
dropout=self.attention_dropout if self.training else 0.0,
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 Gemma3DecoderLayer(GradientCheckpointingLayer):
def __init__(self, config: Gemma3TextConfig, layer_idx: int):
super().__init__()
self.config = config
self.hidden_size = config.hidden_size
self.layer_idx = layer_idx
self.self_attn = Gemma3Attention(config=config, layer_idx=layer_idx)
self.mlp = Gemma3MLP(config)
self.input_layernorm = Gemma3RMSNorm(self.hidden_size, eps=config.rms_norm_eps)
self.post_attention_layernorm = Gemma3RMSNorm(self.hidden_size, eps=config.rms_norm_eps)
self.pre_feedforward_layernorm = Gemma3RMSNorm(self.hidden_size, eps=config.rms_norm_eps)
self.post_feedforward_layernorm = Gemma3RMSNorm(self.hidden_size, eps=config.rms_norm_eps)
def forward(
self,
hidden_states: torch.Tensor,
position_embeddings: torch.Tensor = None,
attention_mask: torch.Tensor | None = None,
position_ids: torch.LongTensor | None = None,
past_key_values: Cache | None = None,
**kwargs: Unpack[TransformersKwargs],
) -> tuple[torch.FloatTensor, tuple[torch.FloatTensor, torch.FloatTensor] | None]:
residual = hidden_states
hidden_states = self.input_layernorm(hidden_states)
hidden_states, _ = self.self_attn(
hidden_states=hidden_states,
position_embeddings=position_embeddings,
attention_mask=attention_mask,
position_ids=position_ids,
past_key_values=past_key_values,
**kwargs,
)
hidden_states = self.post_attention_layernorm(hidden_states)
hidden_states = residual + hidden_states
residual = hidden_states
hidden_states = self.pre_feedforward_layernorm(hidden_states)
hidden_states = self.mlp(hidden_states)
hidden_states = self.post_feedforward_layernorm(hidden_states)
hidden_states = residual + hidden_states
return hidden_states
@auto_docstring
class Gemma3PreTrainedModel(PreTrainedModel):
config: Gemma3Config
base_model_prefix = "model"
supports_gradient_checkpointing = True
_no_split_modules = [
"Gemma3DecoderLayer",
"SiglipVisionEmbeddings",
"SiglipEncoderLayer",
"SiglipMultiheadAttentionPoolingHead",
]
_skip_keys_device_placement = ["past_key_values"]
_supports_flash_attn = True
_supports_sdpa = True
_supports_flex_attn = True
_can_compile_fullgraph = True
_supports_attention_backend = True
_can_record_outputs = {
"hidden_states": Gemma3DecoderLayer,
"attentions": Gemma3Attention,
}
input_modalities = ("image", "text")
@torch.no_grad()
def _init_weights(self, module):
super()._init_weights(module)
if isinstance(module, Gemma3MultiModalProjector):
init.zeros_(module.mm_input_projection_weight)
# We initialize with 0s to be 1 centered as the RMSNorm here does (1 + weight)
elif "RMSNorm" in module.__class__.__name__:
init.zeros_(module.weight)
elif isinstance(module, Gemma3TextScaledWordEmbedding):
init.constant_(module.embed_scale, module.scalar_embed_scale)
elif isinstance(module, Gemma3RotaryEmbedding):
for layer_type in module.layer_types:
rope_init_fn = module.compute_default_rope_parameters
if module.rope_type[layer_type] != "default":
rope_init_fn = ROPE_INIT_FUNCTIONS[module.rope_type[layer_type]]
curr_inv_freq, _ = rope_init_fn(module.config, layer_type=layer_type)
init.copy_(getattr(module, f"{layer_type}_inv_freq"), curr_inv_freq)
init.copy_(getattr(module, f"{layer_type}_original_inv_freq"), curr_inv_freq)
def _bidirectional_window_overlay(sliding_window: int) -> Callable[[int, int, int, int], bool]:
"""
Enables a bidirectional mask within the sliding window.
"""
def inner_mask(batch_idx: int, head_idx: int, q_idx: int, kv_idx: int) -> bool:
"""A token can attend to any other token if their absolute distance is within
the (exclusive) sliding window size (distance < sliding_window)."""
return abs(q_idx - kv_idx) < sliding_window
return inner_mask
@auto_docstring
class Gemma3TextModel(Gemma3PreTrainedModel):
config: Gemma3TextConfig
input_modalities = ("text",)
def __init__(self, config: Gemma3TextConfig):
super().__init__(config)
self.padding_idx = config.pad_token_id
self.vocab_size = config.vocab_size
# Gemma3 downcasts the below to bfloat16, causing sqrt(3072)=55.4256 to become 55.5. See https://github.com/huggingface/transformers/pull/29402
self.embed_tokens = Gemma3TextScaledWordEmbedding(
config.vocab_size, config.hidden_size, self.padding_idx, embed_scale=self.config.hidden_size**0.5
)
self.layers = nn.ModuleList(
[Gemma3DecoderLayer(config, layer_idx) for layer_idx in range(config.num_hidden_layers)]
)
self.norm = Gemma3RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
self.rotary_emb = Gemma3RotaryEmbedding(config)
self.gradient_checkpointing = False
# p2.8 Core Components (Pure Zero-Shot)
self.p28_injection = LTIInjection(config.hidden_size)
self.p28_refine_weight = 0.05 # Winning RefineWeight from Sweep
# p2.8 Runtime Metrics (Heuristic-based)
self._phi_log = 1.0
self._lambda_log = 0.0
# Initialize weights and apply final processing
self.post_init()
# Ensure custom modules are in the right dtype
if hasattr(config, "torch_dtype") and config.torch_dtype is not None:
self.p28_injection.to(config.torch_dtype)
@merge_with_config_defaults
@capture_outputs
@auto_docstring
def forward(
self,
input_ids: torch.LongTensor | None = None,
attention_mask: torch.Tensor | None = None,
position_ids: torch.LongTensor | None = None,
past_key_values: Cache | None = None,
inputs_embeds: torch.FloatTensor | None = None,
use_cache: bool | None = None,
**kwargs: Unpack[TransformersKwargs],
) -> 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)
if use_cache and past_key_values is None:
past_key_values = DynamicCache(config=self.config)
if position_ids is None:
past_seen_tokens = past_key_values.get_seq_length() if past_key_values is not None else 0
position_ids = torch.arange(inputs_embeds.shape[1], device=inputs_embeds.device) + past_seen_tokens
position_ids = position_ids.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,
"inputs_embeds": inputs_embeds,
"attention_mask": attention_mask,
"past_key_values": past_key_values,
"position_ids": position_ids,
}
sliding_mask_kwargs = mask_kwargs.copy()
if self.config.use_bidirectional_attention:
mask_kwargs["or_mask_function"] = lambda *args: torch.tensor(True, dtype=torch.bool)
sliding_mask_kwargs["or_mask_function"] = _bidirectional_window_overlay(self.config.sliding_window)
# Create the masks
causal_mask_mapping = {
"full_attention": create_causal_mask(**mask_kwargs),
"sliding_attention": create_sliding_window_causal_mask(**sliding_mask_kwargs),
}
# embed positions
hidden_states = inputs_embeds
position_embeddings = {}
for layer_type in set(self.config.layer_types):
position_embeddings[layer_type] = self.rotary_emb(hidden_states, position_ids, layer_type)
# --- START p2.8 ARCHITECTURE ---
# 1. Prelude (Layers 0-5)
for i in range(6):
hidden_states = self.layers[i](
hidden_states,
attention_mask=causal_mask_mapping[self.config.layer_types[i]],
position_embeddings=position_embeddings[self.config.layer_types[i]],
position_ids=position_ids,
past_key_values=past_key_values,
**kwargs,
)
# 2. Recurrent Block (Layers 6-11)
e_static = hidden_states.clone() # Anchor snapshot
h = hidden_states
B, T, D = h.shape
phi_history = []
phi = 1.0
loop_outputs = []
n_loops_base = 2
t = 0
while t < 4: # Hard limit for safety
h_prev = h.clone()
# Mode Selection: Linear State Progression (LSP)
if t == 0:
e_mode = e_static
else:
phi_val = max(0.0, min(1.0, phi))
alpha = max(0.0, min(0.5, (1.0 - phi_val) * 2.0))
e_mode = (1.0 - alpha) * e_static + alpha * h_prev.clone()
# p5.1: Context-Preserving KV-Sync
if t == 0:
current_past = past_key_values
elif past_key_values is not None:
current_past = ReadOnlyCache(past_key_values)
else:
current_past = None
trans_out = h
for i_loop in range(6, 12):
l_type = self.config.layer_types[i_loop]
layer_out = self.layers[i_loop](
trans_out,
attention_mask=causal_mask_mapping[l_type],
position_embeddings=position_embeddings[l_type],
position_ids=position_ids,
past_key_values=current_past,
**kwargs,
)
trans_out = layer_out[0] if isinstance(layer_out, (tuple, list)) else layer_out
# Injection
h = self.p28_injection(h_prev, e_mode, trans_out)
phi_tensor = StabilityMonitor.calculate_phi(h, h_prev)
phi = phi_tensor.item()
phi_history.append(phi_tensor)
# p4.0: Lambda-Gated State Reset (LGSR)
lambda_val = StabilityMonitor.detect_lambda(h, e_static).item()
# p5.2: Orthogonal Thinking (OT)
if t > 0:
dot_he = (h * e_static).sum(dim=-1, keepdim=True)
dot_ee = (e_static * e_static).sum(dim=-1, keepdim=True)
proj = (dot_he / (dot_ee + 1e-6)) * e_static
ortho = h - proj
# Dampen Identity drift, keep Orthogonal logic
h = 0.95 * proj + 1.05 * ortho
if lambda_val > 0.55:
h = 0.8 * h + 0.2 * e_static # Pull back to manifold
loop_outputs.append(h.clone())
t += 1
# Dynamic Expansion Logic
if t == n_loops_base:
avg_phi = torch.stack(phi_history).mean().item()
if avg_phi < 0.85: # threshold from DEFAULT_PHI_LOOP_THRESHOLD
continue
else:
break
elif t >= n_loops_base + 1:
break
# Final Normalized Blend (Signal Preservation)
phi0 = phi_history[0].item()
# p4.1: Quadratic Beta Interpolation (QBI) Approximation
b_min = 0.05
b_max = 0.18
beta_final = b_min + (b_max - b_min) * (phi0 ** 2)
if len(loop_outputs) > 1:
h_base = loop_outputs[0]
h_t1 = loop_outputs[1]
if len(loop_outputs) > 2:
h_t2 = loop_outputs[2]
h_refined = 0.7 * h_t1 + 0.3 * h_t2
beta_final = beta_final * 0.8
else:
h_refined = h_t1
hidden_states = (1.0 - beta_final) * h_base + beta_final * h_refined
else:
hidden_states = loop_outputs[0]
# Store diagnostics
self._phi_log = torch.stack(phi_history).mean().item()
self._lambda_log = StabilityMonitor.detect_lambda(hidden_states, e_static).item()
# 3. Coda (Layers 12-17)
for i in range(12, 18):
hidden_states = self.layers[i](
hidden_states,
attention_mask=causal_mask_mapping[self.config.layer_types[i]],
position_embeddings=position_embeddings[self.config.layer_types[i]],
position_ids=position_ids,
past_key_values=past_key_values,
**kwargs,
)
# --- END p2.8 ARCHITECTURE ---
hidden_states = self.norm(hidden_states)
return BaseModelOutputWithPast(
last_hidden_state=hidden_states,
past_key_values=past_key_values,
)
@auto_docstring
class Gemma3ForCausalLM(Gemma3PreTrainedModel, GenerationMixin):
_tied_weights_keys = {"lm_head.weight": "model.embed_tokens.weight"}
_tp_plan = {"lm_head": "colwise_gather_output"}
_pp_plan = {"lm_head": (["hidden_states"], ["logits"])}
config: Gemma3TextConfig
def __init__(self, config: Gemma3TextConfig):
super().__init__(config)
self.model = Gemma3TextModel(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()
@can_return_tuple
@auto_docstring
def forward(
self,
input_ids: torch.LongTensor | None = None,
attention_mask: torch.Tensor | None = None,
position_ids: torch.LongTensor | None = None,
past_key_values: Cache | None = None,
inputs_embeds: torch.FloatTensor | None = None,
labels: torch.LongTensor | None = None,
use_cache: bool | None = None,
logits_to_keep: int | torch.Tensor = 0,
**kwargs: Unpack[TransformersKwargs],
) -> CausalLMOutputWithPast:
r"""
Example:
```python
>>> from transformers import AutoTokenizer, Gemma3ForCausalLM
>>> model = Gemma3ForCausalLM.from_pretrained("google/gemma-2-9b")
>>> tokenizer = AutoTokenizer.from_pretrained("google/gemma-2-9b")
>>> prompt = "What is your favorite condiment?"
>>> 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]
"What is your favorite condiment?"
```"""
# decoder outputs consists of (dec_features, layer_state, dec_hidden, dec_attn)
outputs: BaseModelOutputWithPast = 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,
**kwargs,
)
hidden_states = outputs.last_hidden_state
# Only compute necessary logits, 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, :])
if self.config.final_logit_softcapping is not None:
logits = logits / self.config.final_logit_softcapping
logits = torch.tanh(logits)
logits = logits * self.config.final_logit_softcapping
loss = None
if labels is not None:
loss = self.loss_function(logits, labels, self.vocab_size, **kwargs)
return CausalLMOutputWithPast(
loss=loss,
logits=logits,
past_key_values=outputs.past_key_values,
hidden_states=outputs.hidden_states,
attentions=outputs.attentions,
)
class Gemma3MultiModalProjector(nn.Module):
def __init__(self, config: Gemma3Config):
super().__init__()
self.mm_input_projection_weight = nn.Parameter(
torch.zeros(config.vision_config.hidden_size, config.text_config.hidden_size)
)
self.mm_soft_emb_norm = Gemma3RMSNorm(
config.vision_config.hidden_size, eps=config.vision_config.layer_norm_eps
)
self.patches_per_image = int(config.vision_config.image_size // config.vision_config.patch_size)
self.tokens_per_side = int(config.mm_tokens_per_image**0.5)
self.kernel_size = self.patches_per_image // self.tokens_per_side
self.avg_pool = nn.AvgPool2d(kernel_size=self.kernel_size, stride=self.kernel_size)
def forward(self, vision_outputs: torch.Tensor):
batch_size, _, hidden_size = vision_outputs.shape
reshaped_vision_outputs = vision_outputs.transpose(1, 2)
reshaped_vision_outputs = reshaped_vision_outputs.reshape(
batch_size, hidden_size, self.patches_per_image, self.patches_per_image
)
reshaped_vision_outputs = reshaped_vision_outputs.contiguous()
pooled_vision_outputs = self.avg_pool(reshaped_vision_outputs)
pooled_vision_outputs = pooled_vision_outputs.flatten(2)
pooled_vision_outputs = pooled_vision_outputs.transpose(1, 2)
normed_vision_outputs = self.mm_soft_emb_norm(pooled_vision_outputs)
projected_vision_outputs = torch.matmul(normed_vision_outputs, self.mm_input_projection_weight)
return projected_vision_outputs.type_as(vision_outputs)
def get_block_sequence_ids_for_mask(token_type_ids: torch.Tensor, device: torch.device | None = None) -> torch.Tensor:
# First find where a new image block starts: 1 if image and previous not image
# The images cannot attend to future images, but can attend to all prev images and to itself bidirectionally
is_image = (token_type_ids == 1).to(device=device)
is_previous_image = nn.functional.pad(is_image, (1, 0), value=0)[:, :-1]
new_image_start = is_image & ~is_previous_image
group_ids = torch.cumsum(new_image_start.int(), dim=1) - 1
block_sequence_ids = torch.where(is_image, group_ids, -1)
return block_sequence_ids
@auto_docstring(
custom_intro="""
The Base Gemma3 model which consists of a vision backbone and a language model without language modeling head.,
"""
)
class Gemma3Model(Gemma3PreTrainedModel):
# we are filtering the logits/labels so we shouldn't divide the loss based on num_items_in_batch
accepts_loss_kwargs = False
def __init__(self, config: Gemma3Config):
super().__init__(config)
self.vision_tower = AutoModel.from_config(config=config.vision_config)
self.multi_modal_projector = Gemma3MultiModalProjector(config)
self.vocab_size = config.text_config.vocab_size
language_model = AutoModel.from_config(config=config.text_config)
self.language_model = language_model
self.post_init()
@can_return_tuple
@auto_docstring(custom_intro="Projects the last hidden state from the vision model into language model space.")
def get_image_features(
self, pixel_values: torch.FloatTensor, **kwargs: Unpack[TransformersKwargs]
) -> tuple | BaseModelOutputWithPooling:
vision_outputs = self.vision_tower(pixel_values=pixel_values, return_dict=True, **kwargs)
last_hidden_state = vision_outputs.last_hidden_state
vision_outputs.pooler_output = self.multi_modal_projector(last_hidden_state)
return vision_outputs
def get_placeholder_mask(
self, input_ids: torch.LongTensor, inputs_embeds: torch.FloatTensor, image_features: torch.FloatTensor
):
"""
Obtains multimodal placeholder mask from `input_ids` or `inputs_embeds`, and checks that the placeholder token count is
equal to the length of multimodal features. If the lengths are different, an error is raised.
"""
if input_ids is None:
special_image_mask = inputs_embeds == self.get_input_embeddings()(
torch.tensor(self.config.image_token_id, dtype=torch.long, device=inputs_embeds.device)
)
special_image_mask = special_image_mask.all(-1)
else:
special_image_mask = input_ids == self.config.image_token_id
n_image_tokens = special_image_mask.sum()
n_image_features = image_features.shape[0] * image_features.shape[1]
special_image_mask = special_image_mask.unsqueeze(-1).expand_as(inputs_embeds).to(inputs_embeds.device)
torch_compilable_check(
inputs_embeds[special_image_mask].numel() == image_features.numel(),
f"Image features and image tokens do not match, tokens: {n_image_tokens}, features: {n_image_features}",
)
return special_image_mask
@can_return_tuple
@auto_docstring
def forward(
self,
input_ids: torch.LongTensor | None = None,
pixel_values: torch.FloatTensor | None = None,
attention_mask: torch.Tensor | None = None,
position_ids: torch.LongTensor | None = None,
past_key_values: Cache | None = None,
token_type_ids: torch.LongTensor | None = None,
inputs_embeds: torch.FloatTensor | None = None,
labels: torch.LongTensor | None = None,
use_cache: bool | None = None,
**lm_kwargs: Unpack[TransformersKwargs],
) -> tuple | Gemma3ModelOutputWithPast:
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.text_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.text_config.vocab_size]`.
Example:
```python
>>> from PIL import Image
>>> import httpx
>>> from io import BytesIO
>>> from transformers import AutoProcessor, Gemma3ForConditionalGeneration
>>> model = Gemma3ForConditionalGeneration.from_pretrained("google/gemma32-3b-mix-224")
>>> processor = AutoProcessor.from_pretrained("google/gemma32-3b-mix-224")
>>> prompt = "Where is the cat standing?"
>>> url = "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/pipeline-cat-chonk.jpeg"
>>> with httpx.stream("GET", url) as response:
... image = Image.open(BytesIO(response.read()))
>>> inputs = processor(images=image, text=prompt, return_tensors="pt")
>>> # Generate
>>> generate_ids = model.generate(**inputs,)
>>> processor.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
"Where is the cat standing?\nsnow"
```"""
if (input_ids is None) ^ (inputs_embeds is not None):
raise ValueError("You must specify exactly one of input_ids or inputs_embeds")
# Replace image id with PAD if the image token if OOV, to avoid index-errors
if input_ids is not None and self.config.image_token_id >= self.vocab_size:
special_image_mask = input_ids == self.config.image_token_id
llm_input_ids = input_ids.clone()
llm_input_ids[special_image_mask] = 0
else:
llm_input_ids = input_ids
if inputs_embeds is None:
inputs_embeds = self.get_input_embeddings()(llm_input_ids)
# Merge text and images
if pixel_values is not None:
image_features = self.get_image_features(pixel_values, return_dict=True).pooler_output
image_features = image_features.to(inputs_embeds.device, inputs_embeds.dtype)
special_image_mask = self.get_placeholder_mask(
input_ids, inputs_embeds=inputs_embeds, image_features=image_features
)
inputs_embeds = inputs_embeds.masked_scatter(special_image_mask, image_features)
# It may already have been prepared by e.g. `generate`
if not isinstance(causal_mask_mapping := attention_mask, dict):
mask_kwargs = {
"config": self.config.get_text_config(),
"inputs_embeds": inputs_embeds,
"attention_mask": attention_mask,
"past_key_values": past_key_values,
"position_ids": position_ids,
}
if token_type_ids is not None:
mask_kwargs["block_sequence_ids"] = get_block_sequence_ids_for_mask(
token_type_ids, device=inputs_embeds.device
)
# Create the masks
sliding_mask_kwargs = mask_kwargs.copy()
causal_mask_mapping = {
"full_attention": create_causal_mask(**mask_kwargs),
"sliding_attention": create_sliding_window_causal_mask(**sliding_mask_kwargs),
}
outputs = self.language_model(
attention_mask=causal_mask_mapping,
position_ids=position_ids,
past_key_values=past_key_values,
inputs_embeds=inputs_embeds,
use_cache=use_cache,
return_dict=True,
**lm_kwargs,
)
return Gemma3ModelOutputWithPast(
last_hidden_state=outputs.last_hidden_state,
past_key_values=outputs.past_key_values,
hidden_states=outputs.hidden_states,
attentions=outputs.attentions,
image_hidden_states=image_features if pixel_values is not None else None,
)
@auto_docstring(
custom_intro="""
The Base Gemma3 model which consists of a vision backbone and a language model without language modeling head.,
"""
)
class Gemma3ForConditionalGeneration(Gemma3PreTrainedModel, GenerationMixin):
_tied_weights_keys = {"lm_head.weight": "model.language_model.embed_tokens.weight"}
# we are filtering the logits/labels so we shouldn't divide the loss based on num_items_in_batch
# Fix: https://github.com/huggingface/transformers/issues/40564
accepts_loss_kwargs = False
def __init__(self, config: Gemma3Config):
super().__init__(config)
self.model = Gemma3Model(config)
self.lm_head = nn.Linear(config.text_config.hidden_size, config.text_config.vocab_size, bias=False)
self.post_init()
@auto_docstring
def get_image_features(self, pixel_values: torch.FloatTensor, **kwargs: Unpack[TransformersKwargs]):
return self.model.get_image_features(pixel_values, **kwargs)
@can_return_tuple
@auto_docstring
def forward(
self,
input_ids: torch.LongTensor | None = None,
pixel_values: torch.FloatTensor | None = None,
attention_mask: torch.Tensor | None = None,
position_ids: torch.LongTensor | None = None,
past_key_values: Cache | None = None,
token_type_ids: torch.LongTensor | None = None,
inputs_embeds: torch.FloatTensor | None = None,
labels: torch.LongTensor | None = None,
use_cache: bool | None = None,
logits_to_keep: int | torch.Tensor = 0,
**lm_kwargs: Unpack[TransformersKwargs],
) -> tuple | Gemma3CausalLMOutputWithPast:
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.text_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.text_config.vocab_size]`.
Example:
```python
>>> from PIL import Image
>>> import httpx
>>> from io import BytesIO
>>> from transformers import AutoProcessor, Gemma3ForConditionalGeneration
>>> model = Gemma3ForConditionalGeneration.from_pretrained("google/gemma-3-4b-it")
>>> processor = AutoProcessor.from_pretrained("google/gemma-3-4b-it")
>>> messages = [
... {
... "role": "system",
... "content": [
... {"type": "text", "text": "You are a helpful assistant."}
... ]
... },
... {
... "role": "user", "content": [
... {"type": "image", "url": "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/pipeline-cat-chonk.jpeg"},
... {"type": "text", "text": "Where is the cat standing?"},
... ]
... },
... ]
>>> inputs = processor.apply_chat_template(
... messages,
... tokenize=True,
... return_dict=True,
... return_tensors="pt",
... add_generation_prompt=True
... )
>>> # Generate
>>> generate_ids = model.generate(**inputs)
>>> processor.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
"user\nYou are a helpful assistant.\n\n\n\n\n\nWhere is the cat standing?\nmodel\nBased on the image, the cat is standing in a snowy area, likely outdoors. It appears to"
```
"""
outputs = self.model(
input_ids=input_ids,
pixel_values=pixel_values,
token_type_ids=token_type_ids,
attention_mask=attention_mask,
position_ids=position_ids,
past_key_values=past_key_values,
inputs_embeds=inputs_embeds,
use_cache=use_cache,
labels=labels,
return_dict=True,
**lm_kwargs,
)
hidden_states = outputs[0]
# Only compute necessary logits, 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:
# Upcast to float if we need to compute the loss to avoid potential precision issues
logits = logits.float()
shift_logits = logits[..., :-1, :]
shift_labels = labels[..., 1:]
if attention_mask is not None:
# we use the input attention mask to shift the logits and labels, because it is 2D.
# we also crop attn mask in case it is longer, which happens in PrefixTuning with peft
shift_attention_mask = attention_mask[:, -shift_logits.shape[1] :].to(logits.device)
shift_logits = shift_logits[shift_attention_mask.to(logits.device) != 0].contiguous()
shift_labels = shift_labels[shift_attention_mask.to(shift_labels.device) != 0].contiguous()
else:
shift_logits = shift_logits.contiguous()
shift_labels = shift_labels.contiguous()
# Flatten the tokens
loss_fct = nn.CrossEntropyLoss()
flat_logits = shift_logits.view(-1, self.config.text_config.vocab_size)
flat_labels = shift_labels.view(-1).to(shift_logits.device)
loss = loss_fct(flat_logits, flat_labels)
return Gemma3CausalLMOutputWithPast(
loss=loss,
logits=logits,
past_key_values=outputs.past_key_values,
hidden_states=outputs.hidden_states,
attentions=outputs.attentions,
image_hidden_states=outputs.image_hidden_states,
)
def prepare_inputs_for_generation(
self,
input_ids,
past_key_values=None,
inputs_embeds=None,
position_ids=None,
pixel_values=None,
attention_mask=None,
token_type_ids=None,
use_cache=True,
logits_to_keep=None,
labels=None,
is_first_iteration=False,
**kwargs,
):
# Overwritten -- custom `pixel_values` handling
model_inputs = super().prepare_inputs_for_generation(
input_ids,
past_key_values=past_key_values,
inputs_embeds=inputs_embeds,
attention_mask=attention_mask,
position_ids=position_ids,
use_cache=use_cache,
logits_to_keep=logits_to_keep,
token_type_ids=token_type_ids,
is_first_iteration=is_first_iteration,
**kwargs,
)
# Pixel values are used only in the first iteration if available
# In subsequent iterations, they are already merged with text and cached
# NOTE: first iteration doesn't have to be prefill, it can be the first
# iteration with a question and cached system prompt (continue generate from cache). NOTE: use_cache=False needs pixel_values always
if is_first_iteration or not use_cache:
model_inputs["pixel_values"] = pixel_values
else:
# Don't pass to not apply bidirectional mask on top
model_inputs["token_type_ids"] = None
return model_inputs
@staticmethod
def create_masks_for_generate(
config: PreTrainedConfig,
inputs_embeds: torch.Tensor,
attention_mask: torch.Tensor | None,
past_key_values: Cache | None,
position_ids: torch.Tensor | None,
token_type_ids: torch.Tensor | None = None,
is_first_iteration: bool | None = False,
**kwargs,
) -> dict:
mask_kwargs = {
"config": config.get_text_config(),
"inputs_embeds": inputs_embeds,
"attention_mask": attention_mask,
"past_key_values": past_key_values,
"position_ids": position_ids,
}
if token_type_ids is not None:
mask_kwargs["block_sequence_ids"] = get_block_sequence_ids_for_mask(
token_type_ids, device=inputs_embeds.device
)
return create_masks_for_generate(**mask_kwargs)
@auto_docstring(
custom_intro="""
Gemma3TextForSequenceClassification is a text-only sequence classification model that works with Gemma3TextConfig.
It uses the generic sequence classification implementation for efficiency and consistency."""
)
class Gemma3TextForSequenceClassification(GenericForSequenceClassification, Gemma3PreTrainedModel):
config: Gemma3TextConfig
input_modalities = ("text",)
class Gemma3ForSequenceClassification(GenericForSequenceClassification, Gemma3PreTrainedModel):
def forward(
self,
input_ids: torch.LongTensor | None = None,
pixel_values: torch.FloatTensor | None = None,
attention_mask: torch.Tensor | None = None,
position_ids: torch.LongTensor | None = None,
past_key_values: Cache | None = None,
token_type_ids: torch.LongTensor | None = None,
inputs_embeds: torch.FloatTensor | None = None,
labels: torch.LongTensor | None = None,
**kwargs: Unpack[TransformersKwargs],
) -> SequenceClassifierOutputWithPast:
return super().forward(
input_ids=input_ids,
attention_mask=attention_mask,
position_ids=position_ids,
past_key_values=past_key_values,
inputs_embeds=inputs_embeds,
pixel_values=pixel_values,
token_type_ids=token_type_ids,
labels=labels,
**kwargs,
)
__all__ = [
"Gemma3PreTrainedModel",
"Gemma3TextModel",
"Gemma3ForCausalLM",
"Gemma3ForConditionalGeneration",
"Gemma3Model",
"Gemma3ForSequenceClassification",
"Gemma3TextForSequenceClassification",
]