# 🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨
# This file was automatically generated from src/transformers/models/bamba/modular_bamba.py.
# Do NOT edit this file manually as any edits will be overwritten by the generation of
# the file from the modular. If any change should be done, please apply the change to the
# modular_bamba.py file directly. One of our CI enforces this.
# 🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨🚨
# coding=utf-8
# Copyright 2024 IBM and the HuggingFace Inc. team. All rights reserved.
#
# This code is based on EleutherAI's GPT-NeoX library and the GPT-NeoX
# and OPT implementations in this library. It has been modified from its
# original forms to accommodate minor architectural differences compared
# to GPT-NeoX and OPT used by the Meta AI team that trained the model.
#
# 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 typing import Callable, Optional, Tuple, Union
import torch
from torch import nn
import transformers.models.jamba.modeling_jamba as modeling_jamba
from transformers.activations import ACT2FN
from ...cache_utils import Cache # we need __iter__ and __len__ of pkv
from ...generation import GenerationMixin
from ...modeling_attn_mask_utils import AttentionMaskConverter
from ...modeling_flash_attention_utils import FlashAttentionKwargs
from ...modeling_outputs import BaseModelOutputWithPast, CausalLMOutputWithPast
from ...modeling_rope_utils import ROPE_INIT_FUNCTIONS, dynamic_rope_update
from ...modeling_utils import ALL_ATTENTION_FUNCTIONS, PreTrainedModel
from ...processing_utils import Unpack
from ...utils import (
add_start_docstrings,
add_start_docstrings_to_model_forward,
can_return_tuple,
logging,
replace_return_docstrings,
)
from ...utils.deprecation import deprecate_kwarg
from ...utils.import_utils import is_causal_conv1d_available, is_mamba_2_ssm_available
from .configuration_bamba import BambaConfig
if is_mamba_2_ssm_available():
from mamba_ssm.ops.triton.selective_state_update import selective_state_update
from mamba_ssm.ops.triton.ssd_combined import mamba_chunk_scan_combined, mamba_split_conv1d_scan_combined
else:
selective_state_update = None
if is_causal_conv1d_available():
from causal_conv1d import causal_conv1d_fn, causal_conv1d_update
else:
causal_conv1d_update, causal_conv1d_fn = None, None
logger = logging.get_logger(__name__)
_CONFIG_FOR_DOC = "BambaConfig"
# Adapted from transformers.models.jamba.modeling_jamba.HybridMambaAttentionDynamicCache for the v2 mixer
class HybridMambaAttentionDynamicCache(modeling_jamba.HybridMambaAttentionDynamicCache):
"""
A dynamic cache that can handle both the attention cache (which has a seq_len dimension) and the mamba cache
(which has a constant shape regardless of seq_len).
This cache has two sets of lists of tensors: `key_cache` and `value_cache` for attention cache and `conv_states`
and `ssm_states` for mamba cache. Each of these lists has `num_layers` tensors. The expected shape for each tensor
For attention layers, `key_cache` and `value_cache` have a shape of `(batch_size, num_heads, seq_len, head_dim)`,
while `conv_states` and `ssm_states` have a shape of `(batch_size, 0)` (empty tensors).
For mamba layers, `key_cache` and `value_cache` have a shape of `(batch_size, 0)` (empty tensors),
while `conv_states` represents the convolution state and has a shape of `(batch_size, d_inner, d_conv)`,
and `ssm_states` represents the ssm state and has a shape of `(batch_size, d_inner, d_state)`.
"""
def __init__(self, config: BambaConfig, batch_size, dtype=torch.float16, device=None):
super().__init__(config, batch_size, dtype, device)
self.layers_block_type = config.layers_block_type
self.has_previous_state = False # only used by mamba
conv_kernel_size = config.mamba_d_conv
ssm_state_size = config.mamba_d_state
self.conv_states = []
self.ssm_states = []
self.transformer_layers = []
for i in range(config.num_hidden_layers):
if self.layers_block_type[i] == "mamba":
self.conv_states += [
torch.zeros(
batch_size,
(config.mamba_expand * config.hidden_size + 2 * config.mamba_n_groups * ssm_state_size),
conv_kernel_size,
device=device,
dtype=dtype,
)
]
self.ssm_states += [
torch.zeros(
batch_size,
config.mamba_n_heads,
config.mamba_d_head,
ssm_state_size,
device=device,
dtype=dtype,
)
]
else:
self.conv_states += [torch.tensor([[]] * batch_size, device=device)]
self.ssm_states += [torch.tensor([[]] * batch_size, device=device)]
self.transformer_layers.append(i)
self.key_cache = [torch.tensor([[]] * batch_size, device=device) for _ in range(config.num_hidden_layers)]
self.value_cache = [torch.tensor([[]] * batch_size, device=device) for _ in range(config.num_hidden_layers)]
class BambaRotaryEmbedding(nn.Module):
def __init__(self, config: BambaConfig, device=None):
super().__init__()
# BC: "rope_type" was originally "type"
if hasattr(config, "rope_scaling") and config.rope_scaling is not None:
self.rope_type = config.rope_scaling.get("rope_type", config.rope_scaling.get("type"))
else:
self.rope_type = "default"
self.max_seq_len_cached = config.max_position_embeddings
self.original_max_seq_len = config.max_position_embeddings
self.config = config
self.rope_init_fn = ROPE_INIT_FUNCTIONS[self.rope_type]
inv_freq, self.attention_scaling = self.rope_init_fn(self.config, device)
self.register_buffer("inv_freq", inv_freq, persistent=False)
self.original_inv_freq = self.inv_freq
@torch.no_grad()
@dynamic_rope_update # power user: used with advanced RoPE types (e.g. dynamic rope)
def forward(self, x, position_ids):
inv_freq_expanded = self.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 torch.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() * self.attention_scaling
sin = emb.sin() * self.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)
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: Optional[torch.Tensor],
scaling: float,
dropout: float = 0.0,
**kwargs,
):
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 attention_mask is not None:
causal_mask = attention_mask[:, :, :, : key_states.shape[-2]]
attn_weights = attn_weights + causal_mask
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
# Adapted from transformers.models.glm.modular_glm.apply_rotary_pos_emb
def apply_rotary_pos_emb(q, k, cos, sin, position_ids=None, unsqueeze_dim=1):
"""Applies Rotary Position Embedding to the query and key tensors.
Removes the interleaving of cos and sin from GLM
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.
position_ids (`torch.Tensor`, *optional*):
Deprecated and unused.
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)
# Keep half or full tensor for later concatenation
rotary_dim = cos.shape[-1]
q_rot, q_pass = q[..., :rotary_dim], q[..., rotary_dim:]
k_rot, k_pass = k[..., :rotary_dim], k[..., rotary_dim:]
# Apply rotary embeddings on the first half or full tensor
q_embed = (q_rot * cos) + (rotate_half(q_rot) * sin)
k_embed = (k_rot * cos) + (rotate_half(k_rot) * sin)
# Concatenate back to full shape
q_embed = torch.cat([q_embed, q_pass], dim=-1)
k_embed = torch.cat([k_embed, k_pass], dim=-1)
return q_embed, k_embed
class BambaAttention(nn.Module):
"""Multi-headed attention from 'Attention Is All You Need' paper"""
def __init__(self, config: BambaConfig, layer_idx: int):
super().__init__()
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 = self.head_dim**-0.5
self.attention_dropout = config.attention_dropout
self.is_causal = True
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
)
def forward(
self,
hidden_states: torch.Tensor,
position_embeddings: Tuple[torch.Tensor, torch.Tensor],
attention_mask: Optional[torch.Tensor],
past_key_value: 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).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)
cos, sin = position_embeddings
query_states, key_states = apply_rotary_pos_emb(query_states, key_states, cos, sin)
if past_key_value is not None:
# sin and cos are specific to RoPE models; cache_position needed for the static cache
cache_kwargs = {"sin": sin, "cos": cos, "cache_position": cache_position}
key_states, value_states = past_key_value.update(key_states, value_states, self.layer_idx, cache_kwargs)
attention_interface: Callable = eager_attention_forward
if self.config._attn_implementation != "eager":
if self.config._attn_implementation == "sdpa" and kwargs.get("output_attentions", False):
logger.warning_once(
"`torch.nn.functional.scaled_dot_product_attention` does not support `output_attentions=True`. Falling back to "
'eager attention. This warning can be removed using the argument `attn_implementation="eager"` when loading the model.'
)
else:
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,
**kwargs,
)
attn_output = attn_output.reshape(*input_shape, -1).contiguous()
attn_output = self.o_proj(attn_output)
return attn_output, attn_weights
class BambaRMSNormGated(torch.nn.Module):
def __init__(self, hidden_size, eps=1e-6):
super().__init__()
self.weight = nn.Parameter(torch.ones(hidden_size))
self.variance_epsilon = eps
def forward(self, hidden_states, gate=None):
input_dtype = hidden_states.dtype
hidden_states = hidden_states.to(torch.float32)
if gate is not None:
hidden_states = hidden_states * nn.functional.silu(gate.to(torch.float32))
variance = hidden_states.pow(2).mean(-1, keepdim=True)
hidden_states = hidden_states * torch.rsqrt(variance + self.variance_epsilon)
return self.weight * hidden_states.to(input_dtype)
# Helper methods for segment sum computation
def pad_tensor_by_size(input_tensor: torch.Tensor, pad_size: int):
"""
Padding x tensor with `pad_size` on the seq_len dim (dim=1)
Assumes that we only have tensors of either size 4 or 3
"""
pad_shape = (0, 0, 0, 0, 0, pad_size, 0, 0) if len(input_tensor.shape) == 4 else (0, 0, 0, pad_size, 0, 0)
return torch.nn.functional.pad(input_tensor, pad_shape, mode="constant", value=0)
def reshape_into_chunks(input_tensor, pad_size, chunk_size):
"""
Padding input_tensor with `pad_size` on the seq_len dim (dim=1) and
simultaneously splitting it into chunk sequences.
Assumes that we only have tensors of either size 4 or 3
"""
# [bsz, seq_len, ...] -> [bsz, seq_len multiple of chunk_size, ...]
input_tensor = pad_tensor_by_size(input_tensor, pad_size)
if len(input_tensor.shape) == 3:
# [bsz, seq_len multiple of chunk_size, num_heads] -> [bsz, -1, chunk_size, num_heads]
return input_tensor.reshape(input_tensor.shape[0], -1, chunk_size, input_tensor.shape[2])
else:
# [bsz, seq_len multiple of chunk_size, num_heads, head_dim or state_size] -> [bsz, -1, chunk_size, num_heads, head_dim or state_size]
return input_tensor.reshape(
input_tensor.shape[0], -1, chunk_size, input_tensor.shape[2], input_tensor.shape[3]
)
def segment_sum(input_tensor):
"""
More stable segment sum calculation. Uses cumulative sums and masking instead of direct subtractions.
"""
chunk_size = input_tensor.size(-1)
# 1. expand input tensor to have an additional dimension and repeat along that dimension
# [..., chunk_size] -> [..., chunk_size, chunk_size]
input_tensor = input_tensor[..., None].expand(*input_tensor.size(), chunk_size)
# 2. create a lower triangular mask with the diagonal set to 0 to 0 out elements above diag
mask = torch.tril(torch.ones(chunk_size, chunk_size, device=input_tensor.device, dtype=torch.bool), diagonal=-1)
input_tensor = input_tensor.masked_fill(~mask, 0)
# 3. compute actual cumsum
tensor_segsum = torch.cumsum(input_tensor, dim=-2)
# 4. apply mask to keep only the lower triangular part of the cumulative sum result (incl diagonal this time)
mask = torch.tril(torch.ones(chunk_size, chunk_size, device=input_tensor.device, dtype=torch.bool), diagonal=0)
tensor_segsum = tensor_segsum.masked_fill(~mask, -torch.inf)
return tensor_segsum
is_fast_path_available = all((selective_state_update, causal_conv1d_fn, causal_conv1d_update))
def apply_mask_to_padding_states(hidden_states, attention_mask):
"""
Tunes out the hidden states for padding tokens, see https://github.com/state-spaces/mamba/issues/66
"""
if attention_mask is not None and attention_mask.shape[1] > 1 and attention_mask.shape[0] > 1:
dtype = hidden_states.dtype
hidden_states = (hidden_states * attention_mask[:, :, None]).to(dtype)
return hidden_states
# Adapted from transformers.models.mamba2.modeling_mamba2.Mamba2Mixer
class BambaMixer(nn.Module):
"""
Compute ∆, A, B, C, and D the state space parameters and compute the `contextualized_states`.
A, D are input independent (see Mamba paper [1] Section 3.5.2 "Interpretation of A" for why A isn't selective)
∆, B, C are input-dependent (this is a key difference between Mamba and the linear time invariant S4,
and is why Mamba is called **selective** state spaces)
The are a few differences between this and Mamba2Mixer:
- The variable use_precomputed_states is slightly different due to the HybridCache structure
- There's a few non-obvious bugs fixed with batching in the slow path that exist in main
- Some extra variables that our layer doesn't need have been removed
- We ported most of the refactors in https://github.com/huggingface/transformers/pull/35154, which is (as of Dec 18, 2024) unmerged
"""
def __init__(self, config: BambaConfig, layer_idx: int):
super().__init__()
self.num_heads = config.mamba_n_heads
self.hidden_size = config.hidden_size
self.ssm_state_size = config.mamba_d_state
self.conv_kernel_size = config.mamba_d_conv
self.intermediate_size = int(config.mamba_expand * self.hidden_size)
self.layer_idx = layer_idx
self.use_conv_bias = config.mamba_conv_bias
self.activation = config.hidden_act
self.act = ACT2FN[config.hidden_act]
self.use_bias = config.mamba_proj_bias
self.layer_norm_epsilon = config.rms_norm_eps
self.n_groups = config.mamba_n_groups
self.head_dim = config.mamba_d_head
self.chunk_size = config.mamba_chunk_size
# FIXME:
self.time_step_limit = (0.0, float("inf"))
self.time_step_min = 0.001
self.time_step_max = 0.1
self.conv_dim = self.intermediate_size + 2 * self.n_groups * self.ssm_state_size
self.conv1d = nn.Conv1d(
in_channels=self.conv_dim,
out_channels=self.conv_dim,
bias=config.mamba_conv_bias,
kernel_size=self.conv_kernel_size,
groups=self.conv_dim,
padding=self.conv_kernel_size - 1,
)
# projection of the input hidden states
projection_size = self.intermediate_size + self.conv_dim + self.num_heads
self.in_proj = nn.Linear(
self.hidden_size,
projection_size,
bias=self.use_bias,
)
# selective projection used to make dt, B and C input dependant
# time step projection (discretization)
# instantiate once and copy inv_dt in init_weights of PretrainedModel
self.dt_bias = nn.Parameter(torch.ones(self.num_heads))
# S4D real initialization. These are not discretized!
# The core is to load them, compute the discrete states, then write the updated state. Keeps the memory bounded
A = torch.arange(1, self.num_heads + 1)
self.A_log = nn.Parameter(torch.log(A))
self.A_log._no_weight_decay = True
self.norm = BambaRMSNormGated(self.intermediate_size, eps=self.layer_norm_epsilon)
self.D = nn.Parameter(torch.ones(self.num_heads))
self.D._no_weight_decay = True
self.out_proj = nn.Linear(self.intermediate_size, self.hidden_size, bias=self.use_bias)
if not is_fast_path_available:
logger.warning_once(
"The fast path is not available because on of `(selective_state_update, causal_conv1d_fn, causal_conv1d_update)`"
" is None. Falling back to the naive implementation. To install follow https://github.com/state-spaces/mamba/#installation and"
" https://github.com/Dao-AILab/causal-conv1d"
)
else:
logger.warning_once("The fast path for Bamba will be used when running the model on a GPU")
def cuda_kernels_forward(
self,
hidden_states: torch.Tensor,
cache_params: Optional[HybridMambaAttentionDynamicCache] = None,
cache_position: Optional[torch.LongTensor] = None,
attention_mask: Optional[torch.Tensor] = None,
):
# 1. Gated MLP's linear projection
hidden_states = apply_mask_to_padding_states(hidden_states, attention_mask)
projected_states = self.in_proj(hidden_states)
# Set up dimensions for reshapes later
batch_size, seq_len, _ = hidden_states.shape
groups_time_state_size = self.n_groups * self.ssm_state_size
use_precomputed_states = (
cache_params is not None
and cache_params.has_previous_state
and seq_len == 1
and cache_params.conv_states[self.layer_idx].shape[0]
== cache_params.ssm_states[self.layer_idx].shape[0]
== batch_size
and cache_position is not None
and cache_position[0] > 0
)
# getting projected states from cache if it exists
if use_precomputed_states:
gate, hidden_states_B_C, dt = projected_states.squeeze(1).split(
[self.intermediate_size, self.conv_dim, self.num_heads], dim=-1
)
# 2. Convolution sequence transformation
hidden_states_B_C = causal_conv1d_update(
hidden_states_B_C,
cache_params.conv_states[self.layer_idx],
self.conv1d.weight.squeeze(1),
self.conv1d.bias,
self.activation,
)
hidden_states, B, C = torch.split(
hidden_states_B_C,
[self.intermediate_size, groups_time_state_size, groups_time_state_size],
dim=-1,
)
# 3. SSM transformation
A = -torch.exp(self.A_log.float()) # (nheads,)
A = A[:, None, ...][:, :, None].expand(-1, self.head_dim, self.ssm_state_size).to(dtype=torch.float32)
dt = dt[:, :, None].expand(-1, -1, self.head_dim)
dt_bias = self.dt_bias[:, None, ...].expand(-1, self.head_dim)
D = self.D[:, None, ...].expand(-1, self.head_dim)
B = B.view(batch_size, self.n_groups, B.shape[1] // self.n_groups)
C = C.view(batch_size, self.n_groups, C.shape[1] // self.n_groups)
hidden_states_reshaped = hidden_states.view(batch_size, self.num_heads, self.head_dim)
hidden_states = selective_state_update(
cache_params.ssm_states[self.layer_idx],
hidden_states_reshaped,
dt,
A,
B,
C,
D,
z=None,
dt_bias=dt_bias,
dt_softplus=True,
)
hidden_states = hidden_states.view(batch_size, self.num_heads * self.head_dim)
hidden_states = self.norm(hidden_states, gate)
# 4. Final linear projection
out = self.out_proj(hidden_states)[:, None, ...]
# Fused calculations or step by step if no initialized cache is found
else:
A = -torch.exp(self.A_log.float()) # (num_heads) or (intermediate_size, state_size)
dt_limit_kwargs = {} if self.time_step_limit == (0.0, float("inf")) else {"dt_limit": self.time_step_limit}
# 2-4. Fused kernel for conv1d, SSM, and the final projection
if self.training and cache_params is None:
out = mamba_split_conv1d_scan_combined(
projected_states,
self.conv1d.weight.squeeze(1),
self.conv1d.bias,
self.dt_bias,
A,
D=self.D,
chunk_size=self.chunk_size,
seq_idx=None, # was seq_idx
activation=self.activation,
rmsnorm_weight=self.norm.weight,
rmsnorm_eps=self.norm.variance_epsilon,
outproj_weight=self.out_proj.weight,
outproj_bias=self.out_proj.bias,
headdim=self.head_dim,
ngroups=self.n_groups,
norm_before_gate=False,
return_final_states=False,
**dt_limit_kwargs,
)
else:
gate, hidden_states_B_C, dt = projected_states.split(
[self.intermediate_size, self.conv_dim, self.num_heads], dim=-1
)
# 2. Convolution sequence transformation
# Init cache
if cache_params is not None:
# storing the states
# If we just take xBC[:, :, -self.d_conv :], it will error if seqlen < self.d_conv
# Instead F.pad will pad with zeros if seqlen < self.d_conv, and truncate otherwise.
hidden_states_B_C_transposed = hidden_states_B_C.transpose(1, 2)
conv_states = nn.functional.pad(
hidden_states_B_C_transposed,
(self.conv_kernel_size - hidden_states_B_C_transposed.shape[-1], 0),
)
cache_params.conv_states[self.layer_idx].copy_(conv_states)
if self.activation not in ["silu", "swish"]:
hidden_states_B_C = self.act(
self.conv1d(hidden_states_B_C.transpose(1, 2))[..., :seq_len].transpose(1, 2)
)
else:
hidden_states_B_C = causal_conv1d_fn(
x=hidden_states_B_C.transpose(1, 2),
weight=self.conv1d.weight.squeeze(1),
bias=self.conv1d.bias,
activation=self.activation,
).transpose(1, 2)
hidden_states_B_C = apply_mask_to_padding_states(hidden_states_B_C, attention_mask)
hidden_states, B, C = torch.split(
hidden_states_B_C,
[self.intermediate_size, groups_time_state_size, groups_time_state_size],
dim=-1,
)
# 3. SSM transformation
scan_output, ssm_state = mamba_chunk_scan_combined(
hidden_states.view(batch_size, seq_len, -1, self.head_dim),
dt,
A,
B.view(batch_size, seq_len, self.n_groups, -1),
C.view(batch_size, seq_len, self.n_groups, -1),
chunk_size=self.chunk_size,
D=self.D,
z=None,
seq_idx=None,
return_final_states=True,
dt_bias=self.dt_bias,
dt_softplus=True,
**dt_limit_kwargs,
)
# Init cache
if ssm_state is not None and cache_params is not None:
cache_params.ssm_states[self.layer_idx].copy_(ssm_state)
scan_output = scan_output.view(batch_size, seq_len, -1)
# Multiply "gate" branch and apply extra normalization layer
scan_output = self.norm(scan_output, gate)
# 4. Final linear projection
out = self.out_proj(scan_output)
return out
# fmt: off
def torch_forward(
self,
input_states,
cache_params: Optional[HybridMambaAttentionDynamicCache] = None,
cache_position: Optional[torch.LongTensor] = None,
attention_mask: Optional[torch.Tensor] = None,
):
batch_size, seq_len, _ = input_states.shape
dtype = input_states.dtype
# 1. Gated MLP's linear projection
input_states = apply_mask_to_padding_states(input_states, attention_mask)
projected_states = self.in_proj(input_states)
gate, hidden_states_B_C, dt = projected_states.split(
[self.intermediate_size, self.conv_dim, self.num_heads], dim=-1
)
use_precomputed_states = (
cache_params is not None
and cache_params.has_previous_state
and seq_len == 1
and cache_params.conv_states[self.layer_idx].shape[0]
== cache_params.ssm_states[self.layer_idx].shape[0]
== batch_size
and cache_position is not None
and cache_position[0] > 0
)
# 2. Convolution sequence transformation
if use_precomputed_states:
cache_params.conv_states[self.layer_idx] = cache_params.conv_states[self.layer_idx].roll(shifts=-1, dims=-1)
cache_params.conv_states[self.layer_idx][:, :, -1] = hidden_states_B_C[:, 0, :].to(cache_params.conv_states[self.layer_idx].device)
# We need to guarantee that anything regarding the cache is on the same device
conv_states = cache_params.conv_states[self.layer_idx].to(device=self.conv1d.weight.device)
hidden_states_B_C = torch.sum(
conv_states * self.conv1d.weight.squeeze(1), dim=-1
)
if self.use_conv_bias:
hidden_states_B_C = hidden_states_B_C + self.conv1d.bias
hidden_states_B_C = self.act(hidden_states_B_C)
else:
# Init cache
if cache_params is not None:
hidden_states_B_C_transposed = hidden_states_B_C.transpose(1, 2)
conv_states = nn.functional.pad(
hidden_states_B_C_transposed, (self.conv_kernel_size - hidden_states_B_C_transposed.shape[-1], 0)
)
cache_params.conv_states[self.layer_idx].copy_(conv_states)
hidden_states_B_C = self.act(self.conv1d(hidden_states_B_C.transpose(1, 2))[..., :seq_len].transpose(1, 2))
hidden_states_B_C = apply_mask_to_padding_states(hidden_states_B_C, attention_mask)
hidden_states, B, C = torch.split(
hidden_states_B_C,
[self.intermediate_size, self.n_groups * self.ssm_state_size, self.n_groups * self.ssm_state_size],
dim=-1
)
# 3. SSM transformation
A = -torch.exp(self.A_log.float()) # [num_heads]
if use_precomputed_states:
# We need to guarantee that anything regarding the cache is on the same device
cache_device = cache_params.ssm_states[self.layer_idx].device
# Note: there is no need to pad parameter matrices here, as there is just one new token
# for batched generation
dt = dt[:, 0, :][:, None, ...]
dt = dt.transpose(1, 2).expand(batch_size, dt.shape[-1], self.head_dim)
# [num_heads] -> [num_heads, head_dim]
dt_bias = self.dt_bias[..., None].expand(self.dt_bias.shape[0], self.head_dim)
dt = torch.nn.functional.softplus(dt + dt_bias.to(dt.dtype))
dt = torch.clamp(dt, self.time_step_limit[0], self.time_step_limit[1])
A = A[..., None, None].expand(self.num_heads, self.head_dim, self.ssm_state_size).to(dtype=torch.float32)
# [bsz, num_heads, head_dim, state_size]
dA = (torch.exp(dt[..., None] * A)).to(device=cache_device)
# Discretize B
# [bsz, n_groups * state_size] -> [bsz, n_groups, 1, state_size] ->
# -> [bsz, n_groups, group to head repetition factor, state_size] -> [bsz, num_heads, state_size]
B = B.reshape(batch_size, self.n_groups, -1)[..., None, :]
B = B.expand(batch_size, self.n_groups, self.num_heads // self.n_groups, B.shape[-1]).contiguous()
B = B.reshape(batch_size, -1, B.shape[-1])
# [bsz, num_heads, head_dim, state_size]
dB = dt[..., None] * B[..., None, :]
# Discretize x into dB
# [bsz, intermediate_size] -> [bsz, num_heads, head_dim]
hidden_states = hidden_states.reshape(batch_size, -1, self.head_dim)
dBx = (dB * hidden_states[..., None]).to(device=cache_device)
# State calculation
cache_params.ssm_states[self.layer_idx].copy_(
cache_params.ssm_states[self.layer_idx] * dA + dBx
)
# Subsequent output
# [bsz, n_groups * state_size] -> [bsz, num_heads, state_size]
C = C.reshape(batch_size, self.n_groups, -1)[..., None, :]
C = C.expand(batch_size, self.n_groups, self.num_heads // self.n_groups, C.shape[-1]).contiguous()
C = C.reshape(batch_size, -1, C.shape[-1])
# [bsz, num_heads, head_dim]
ssm_states = cache_params.ssm_states[self.layer_idx].to(device=C.device, dtype=C.dtype) # Shape: [b, h, d, n]
# Reshape ssm_states to merge the first two dimensions
ssm_states_reshaped = ssm_states.view(batch_size * self.num_heads, self.head_dim, self.ssm_state_size) # Shape: [b*h, d, n]
C_reshaped = C.view(batch_size * self.num_heads, self.ssm_state_size, 1) # Shape: [b*h, n, 1]
y = torch.bmm(ssm_states_reshaped, C_reshaped)
y = y.view(batch_size, self.num_heads, self.head_dim)
# D skip connection
# [num_heads] -> [num_heads, head_dim]
D = self.D[..., None].expand(self.D.shape[0], self.head_dim)
y = (y + hidden_states * D).to(y.dtype)
# [bsz, num_heads, head_dim] -> [bsz, 1, intermediate_size]
y = y.reshape(batch_size, -1)[:, None, ...]
else:
# begin ssd naive implementation without einsums
dt = nn.functional.softplus(dt + self.dt_bias)
dt = torch.clamp(dt, self.time_step_limit[0], self.time_step_limit[1])
hidden_states = hidden_states.reshape(batch_size, seq_len, -1, self.head_dim).float()
B = B.reshape(batch_size, seq_len, -1, self.ssm_state_size).float()
C = C.reshape(batch_size, seq_len, -1, self.ssm_state_size).float()
B = B.repeat(1, 1, self.num_heads // self.n_groups, 1)
C = C.repeat(1, 1, self.num_heads // self.n_groups, 1)
pad_size = (self.chunk_size - seq_len % self.chunk_size) % self.chunk_size
D_residual = self.D[..., None] * pad_tensor_by_size(hidden_states, pad_size)
# Discretize x and A
hidden_states = hidden_states * dt[..., None]
A = A.to(hidden_states.dtype) * dt
# Rearrange into blocks/chunks
hidden_states, A, B, C = [reshape_into_chunks(t, pad_size, self.chunk_size) for t in (hidden_states, A, B, C)]
# [bsz, -1, chunk_size, num_heads] -> [bsz, num_heads, -1, chunk_size]
A = A.permute(0, 3, 1, 2)
A_cumsum = torch.cumsum(A, dim=-1)
# 1. Compute the output for each intra-chunk (diagonal blocks)
# This is the analog of a causal mask
L = torch.exp(segment_sum(A))
# Contraction of C and B to get G (attention-weights like)
G_intermediate = C[:, :, :, None, :, :] * B[:, :, None, :, :, :] # shape: (b, c, l, s, h, n)
G = G_intermediate.sum(dim=-1) # shape: (b, c, l, s, h)
# Compute M, equivalent to applying attention mask to weights
M_intermediate = G[..., None] * L.permute(0, 2, 3, 4, 1)[..., None]
M = M_intermediate.sum(dim=-1)
# Compute Y_diag (apply to values)
Y_diag = (M[..., None] * hidden_states[:, :, None]).sum(dim=3)
# 2. Compute the state for each intra-chunk
# (right term of low-rank factorization of off-diagonal blocks; B terms)
decay_states = torch.exp((A_cumsum[:, :, :, -1:] - A_cumsum))
B_decay = B * decay_states.permute(0, -2, -1, 1)[..., None]
states = (B_decay[..., None, :] * hidden_states[..., None]).sum(dim=2)
# 3. Compute the inter-chunk SSM recurrence; produces correct SSM states at chunk boundaries
# (middle term of factorization of off-diag blocks; A terms)
if use_precomputed_states:
previous_states = cache_params.ssm_states[self.layer_idx][:, None, ...].to(device=states.device)
else:
previous_states = torch.zeros_like(states[:, :1])
states = torch.cat([previous_states, states], dim=1)
decay_chunk = torch.exp(segment_sum(nn.functional.pad(A_cumsum[:, :, :, -1], (1, 0))))
decay_chunk = decay_chunk.transpose(1, 3)
new_states = (decay_chunk[..., None, None] * states[:, :, None, ...]).sum(dim=1)
states, ssm_state = new_states[:, :-1], new_states[:, -1]
# 4. Compute state -> output conversion per chunk
# (left term of low-rank factorization of off-diagonal blocks; C terms)
state_decay_out = torch.exp(A_cumsum)
C_times_states = (C[..., None, :] * states[:, :, None, ...])
state_decay_out_permuted = state_decay_out.permute(0, 2, 3, 1)
Y_off = (C_times_states.sum(-1) * state_decay_out_permuted[..., None])
# Add output of intra-chunk and inter-chunk terms (diagonal and off-diagonal blocks)
y = Y_diag + Y_off
# [bsz, -1, self.chunk_size, num_heads, head_dim] -> [bsz, (padded) seq_len, num_heads, head_dim]
y = y.reshape(batch_size, -1, self.num_heads, self.head_dim)
y = y + D_residual
# Cutting off padded chunks
if pad_size > 0:
y = y[:, :seq_len, :, :]
y = y.reshape(batch_size, seq_len, -1)
# Init cache
if ssm_state is not None and cache_params is not None:
cache_params.ssm_states[self.layer_idx].copy_(ssm_state)
scan_output = self.norm(y, gate)
# end ssd naive
# 4. Final linear projection
contextualized_states = self.out_proj(scan_output.to(dtype)) # [batch, seq_len, hidden_size]
return contextualized_states
# fmt: on
def forward(
self,
hidden_states,
cache_params: Optional[HybridMambaAttentionDynamicCache] = None,
cache_position: Optional[torch.LongTensor] = None,
attention_mask: Optional[torch.Tensor] = None,
):
if is_fast_path_available and "cuda" in self.in_proj.weight.device.type:
return self.cuda_kernels_forward(hidden_states, cache_params, cache_position, attention_mask)
dtype = hidden_states.dtype
if attention_mask is not None and attention_mask.shape[1] > 1 and attention_mask.shape[0] > 1:
# tune out hidden states for pad tokens, see https://github.com/state-spaces/mamba/issues/66
hidden_states = (hidden_states * attention_mask[:, :, None]).to(dtype)
return self.torch_forward(hidden_states, cache_params, cache_position, attention_mask)
class BambaMLP(nn.Module):
def __init__(self, config):
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=config.mlp_bias)
self.up_proj = nn.Linear(self.hidden_size, self.intermediate_size, bias=config.mlp_bias)
self.down_proj = nn.Linear(self.intermediate_size, self.hidden_size, bias=config.mlp_bias)
self.act_fn = ACT2FN[config.hidden_act]
def forward(self, x):
down_proj = self.down_proj(self.act_fn(self.gate_proj(x)) * self.up_proj(x))
return down_proj
class BambaRMSNorm(nn.Module):
def __init__(self, hidden_size, eps=1e-6):
"""
BambaRMSNorm is equivalent to T5LayerNorm
"""
super().__init__()
self.weight = nn.Parameter(torch.ones(hidden_size))
self.variance_epsilon = eps
def forward(self, hidden_states):
input_dtype = hidden_states.dtype
hidden_states = hidden_states.to(torch.float32)
variance = hidden_states.pow(2).mean(-1, keepdim=True)
hidden_states = hidden_states * torch.rsqrt(variance + self.variance_epsilon)
return self.weight * hidden_states.to(input_dtype)
def extra_repr(self):
return f"{tuple(self.weight.shape)}, eps={self.variance_epsilon}"
class BambaDecoderLayer(nn.Module):
def __init__(self, config: BambaConfig, layer_idx: int, layer_type: str = "mamba"):
super().__init__()
num_experts = 1
ffn_layer_class = BambaMLP if num_experts == 1 else None
self.feed_forward = ffn_layer_class(config)
self.input_layernorm = BambaRMSNorm(config.hidden_size, eps=config.rms_norm_eps)
self.pre_ff_layernorm = BambaRMSNorm(config.hidden_size, eps=config.rms_norm_eps)
self.layer_type = layer_type
if layer_type == "mamba":
self.mamba = BambaMixer(config=config, layer_idx=layer_idx)
elif layer_type == "attention":
self.self_attn = BambaAttention(config, layer_idx)
else:
raise ValueError("Invalid layer_type")
def forward(
self,
hidden_states: torch.Tensor,
attention_mask: Optional[torch.Tensor] = None,
position_ids: Optional[torch.LongTensor] = None,
past_key_value: Optional[HybridMambaAttentionDynamicCache] = None,
output_attentions: Optional[bool] = False,
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,
) -> Tuple[torch.FloatTensor, Optional[Tuple[torch.FloatTensor, torch.FloatTensor]]]:
"""
Args:
hidden_states (`torch.FloatTensor`): input to the layer of shape `(batch, seq_len, embed_dim)`
attention_mask (`torch.FloatTensor`, *optional*): attention mask of size
`(batch, sequence_length)` where padding elements are indicated by 0.
past_key_value (`HybridMambaAttentionDynamicCache`, *optional*): cached past key and value projection states
output_attentions (`bool`, *optional*):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under
returned tensors for more detail.
use_cache (`bool`, *optional*):
If set to `True`, `past_key_values` key value states are returned and can be used to speed up decoding
(see `past_key_values`).
cache_position (`torch.LongTensor` of shape `(sequence_length)`, *optional*):
Indices depicting the position of the input sequence tokens in the sequence.
position_embeddings (`Tuple[torch.FloatTensor, torch.FloatTensor]`, *optional*):
Tuple containing the cosine and sine positional embeddings of shape `(batch_size, seq_len, head_dim)`,
with `head_dim` being the embedding dimension of each attention head.
kwargs (`dict`, *optional*):
Arbitrary kwargs to be ignored, used for FSDP and other methods that injects code
into the model
"""
residual = hidden_states
hidden_states = self.input_layernorm(hidden_states)
# this is a hybrid decoder layer
if self.layer_type == "mamba":
hidden_states = self.mamba(
hidden_states=hidden_states,
cache_params=past_key_value,
cache_position=cache_position,
attention_mask=attention_mask,
)
self_attn_weights = None
elif self.layer_type == "attention":
hidden_states, self_attn_weights = self.self_attn(
hidden_states=hidden_states,
attention_mask=attention_mask,
position_ids=position_ids,
past_key_value=past_key_value,
output_attentions=output_attentions,
use_cache=use_cache,
cache_position=cache_position,
position_embeddings=position_embeddings,
**kwargs,
)
# residual connection after attention
hidden_states = residual + hidden_states
# feed-forward
residual = hidden_states
hidden_states = self.pre_ff_layernorm(hidden_states)
hidden_states = self.feed_forward(hidden_states)
hidden_states = residual + hidden_states
outputs = (hidden_states,)
if output_attentions:
outputs += (self_attn_weights,)
return outputs
BAMBA_START_DOCSTRING = r"""
This model inherits from [`PreTrainedModel`]. Check the superclass documentation for the generic methods the
library implements for all its model (such as downloading or saving, resizing the input embeddings, pruning heads
etc.)
This model is also a PyTorch [torch.nn.Module](https://pytorch.org/docs/stable/nn.html#torch.nn.Module) subclass.
Use it as a regular PyTorch Module and refer to the PyTorch documentation for all matter related to general usage
and behavior.
Parameters:
config ([`BambaConfig`]):
Model configuration class with all the parameters of the model. Initializing with a config file does not
load the weights associated with the model, only the configuration. Check out the
[`~PreTrainedModel.from_pretrained`] method to load the model weights.
"""
@add_start_docstrings(
"The bare BambaModel outputting raw hidden-states without any specific head on top.",
BAMBA_START_DOCSTRING,
)
class BambaPreTrainedModel(PreTrainedModel):
config_class = BambaConfig
base_model_prefix = "model"
supports_gradient_checkpointing = True
_no_split_modules = ["BambaDecoderLayer"]
_skip_keys_device_placement = "past_key_values"
_supports_flash_attn_2 = True
_supports_sdpa = True
_supports_cache_class = True # Note: only supports HybridMambaAttentionDynamicCache
_is_stateful = True
def _init_weights(self, module):
std = self.config.initializer_range
if isinstance(module, (nn.Linear, nn.Conv1d)):
module.weight.data.normal_(mean=0.0, std=std)
if module.bias is not None:
module.bias.data.zero_()
elif isinstance(module, nn.Embedding):
module.weight.data.normal_(mean=0.0, std=std)
if module.padding_idx is not None:
module.weight.data[module.padding_idx].zero_()
BAMBA_INPUTS_DOCSTRING = r"""
Args:
input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
Indices of input sequence tokens in the vocabulary. Padding will be ignored by default should you provide
it.
Indices can be obtained using [`AutoTokenizer`]. See [`PreTrainedTokenizer.encode`] and
[`PreTrainedTokenizer.__call__`] for details.
[What are input IDs?](../glossary#input-ids)
attention_mask (`torch.Tensor` of shape `(batch_size, sequence_length)`, *optional*):
Mask to avoid performing attention on padding token indices. Mask values selected in `[0, 1]`:
- 1 for tokens that are **not masked**,
- 0 for tokens that are **masked**.
[What are attention masks?](../glossary#attention-mask)
Indices can be obtained using [`AutoTokenizer`]. See [`PreTrainedTokenizer.encode`] and
[`PreTrainedTokenizer.__call__`] for details.
If `past_key_values` is used, optionally only the last `input_ids` have to be input (see
`past_key_values`).
If you want to change padding behavior, you should read [`modeling_opt._prepare_decoder_attention_mask`]
and modify to your needs. See diagram 1 in [the paper](https://arxiv.org/abs/1910.13461) for more
information on the default strategy.
- 1 indicates the head is **not masked**,
- 0 indicates the head is **masked**.
position_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
Indices of positions of each input sequence tokens in the position embeddings. Selected in the range `[0,
config.n_positions - 1]`.
[What are position IDs?](../glossary#position-ids)
past_key_values (`HybridMambaAttentionDynamicCache`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
A HybridMambaAttentionDynamicCache object containing pre-computed hidden-states (keys and values in the
self-attention blocks and convolution and ssm states in the mamba blocks) that can be used (see
`past_key_values` input) to speed up sequential decoding.
Key and value cache tensors have shape `(batch_size, num_heads, seq_len, head_dim)`.
Convolution and ssm states tensors have shape `(batch_size, d_inner, d_conv)` and
`(batch_size, d_inner, d_state)` respectively.
See the `HybridMambaAttentionDynamicCache` class for more details.
If `past_key_values` are used, the user can optionally input only the last `input_ids` (those that
don't have their past key value states given to this model) of shape `(batch_size, 1)` instead of all
`input_ids` of shape `(batch_size, sequence_length)`.
inputs_embeds (`torch.FloatTensor` of shape `(batch_size, sequence_length, hidden_size)`, *optional*):
Optionally, instead of passing `input_ids` you can choose to directly pass an embedded representation. This
is useful if you want more control over how to convert `input_ids` indices into associated vectors than the
model's internal embedding lookup matrix.
use_cache (`bool`, *optional*):
If set to `True`, `past_key_values` key value states are returned and can be used to speed up decoding (see
`past_key_values`).
output_attentions (`bool`, *optional*):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under returned
tensors for more detail.
output_hidden_states (`bool`, *optional*):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors for
more detail.
output_router_logits (`bool`, *optional*):
Whether or not to return the logits of all the routers. They are useful for computing the router loss, and
should not be returned during inference.
return_dict (`bool`, *optional*):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
cache_position (`torch.LongTensor` of shape `(sequence_length)`, *optional*):
Indices depicting the position of the input sequence tokens in the sequence. Contrarily to `position_ids`,
this tensor is not affected by padding. It is used to update the cache in the correct position and to infer
the complete sequence length.
"""
@add_start_docstrings(
"The bare Bamba Model outputting raw hidden-states without any specific head on top.",
BAMBA_START_DOCSTRING,
)
# Adapted from transformers.models.jamba.modeling_jamba.JambaModel
class BambaModel(BambaPreTrainedModel):
"""
Transformer decoder consisting of *config.num_hidden_layers* layers. Each layer is a [`BambaDecoderLayer`]
Args:
config: BambaConfig
"""
def __init__(self, config: BambaConfig):
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)
decoder_layers = []
for i in range(config.num_hidden_layers):
decoder_layers.append(BambaDecoderLayer(config, layer_idx=i, layer_type=config.layers_block_type[i]))
self.layers = nn.ModuleList(decoder_layers)
self._attn_implementation = config._attn_implementation
self.final_layernorm = BambaRMSNorm(config.hidden_size, eps=config.rms_norm_eps)
self.rotary_emb = BambaRotaryEmbedding(config=config)
self.gradient_checkpointing = False
# Initialize weights and apply final processing
self.post_init()
def get_input_embeddings(self):
return self.embed_tokens
def set_input_embeddings(self, value):
self.embed_tokens = value
@can_return_tuple
@add_start_docstrings_to_model_forward(BAMBA_INPUTS_DOCSTRING)
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[HybridMambaAttentionDynamicCache] = None,
inputs_embeds: Optional[torch.FloatTensor] = None,
use_cache: Optional[bool] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
cache_position: Optional[torch.LongTensor] = None,
**kwargs, # NOOP kwargs, for now
) -> BaseModelOutputWithPast:
output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
)
use_cache = use_cache if use_cache is not None else self.config.use_cache
if (input_ids is None) ^ (inputs_embeds is not None):
raise ValueError("You must specify exactly one of input_ids or inputs_embeds")
if self.gradient_checkpointing and self.training and use_cache:
logger.warning_once(
"`use_cache=True` is incompatible with gradient checkpointing. Setting `use_cache=False`."
)
use_cache = False
if inputs_embeds is None:
inputs_embeds = self.embed_tokens(input_ids)
hidden_states = inputs_embeds
if use_cache and past_key_values is None:
logger.warning_once(
"Bamba requires an initialized `HybridMambaAttentionDynamicCache` to return a cache. None was "
"provided, so no cache will be returned."
)
if cache_position is None:
cache_position = torch.arange(hidden_states.shape[1], device=hidden_states.device)
if position_ids is None:
position_ids = cache_position.unsqueeze(0)
causal_mask = self._update_causal_mask(
attention_mask, inputs_embeds, cache_position, past_key_values, output_attentions
)
mamba_mask = self._update_mamba_mask(attention_mask, cache_position)
# create position embeddings to be shared across the decoder layers
position_embeddings = self.rotary_emb(hidden_states, position_ids)
all_hidden_states = () if output_hidden_states else None
all_self_attns = () if output_attentions else None
for decoder_layer in self.layers:
# Depending on the layer type we opt for 2D base attention mask (Mamba) or 4D causal mask (Attention)
layer_mask = mamba_mask if decoder_layer.layer_type == "mamba" else causal_mask
if output_hidden_states:
all_hidden_states += (hidden_states,)
if self.gradient_checkpointing and self.training:
layer_outputs = self._gradient_checkpointing_func(
decoder_layer.__call__,
hidden_states,
layer_mask,
position_ids,
past_key_values,
output_attentions,
use_cache,
cache_position,
position_embeddings,
)
else:
layer_outputs = decoder_layer(
hidden_states,
attention_mask=layer_mask,
position_ids=position_ids,
past_key_value=past_key_values,
output_attentions=output_attentions,
use_cache=use_cache,
cache_position=cache_position,
position_embeddings=position_embeddings,
)
hidden_states = layer_outputs[0]
if output_attentions:
if layer_outputs[1] is not None:
# append attentions only of attention layers. Mamba layers return `None` as the attention weights
all_self_attns += (layer_outputs[1],)
hidden_states = self.final_layernorm(hidden_states)
# add hidden states from the last decoder layer
if output_hidden_states:
all_hidden_states += (hidden_states,)
if past_key_values and not past_key_values.has_previous_state:
past_key_values.has_previous_state = True
next_cache = None if not use_cache else past_key_values
return BaseModelOutputWithPast(
last_hidden_state=hidden_states,
past_key_values=next_cache,
hidden_states=all_hidden_states,
attentions=all_self_attns,
)
def _update_causal_mask(
self,
attention_mask: torch.Tensor,
input_tensor: torch.Tensor,
cache_position: torch.Tensor,
past_key_values: HybridMambaAttentionDynamicCache,
output_attentions: bool,
):
if self.config._attn_implementation == "flash_attention_2":
if attention_mask is not None and 0.0 in attention_mask:
return attention_mask
return None
# For SDPA, when possible, we will rely on its `is_causal` argument instead of its `attn_mask` argument, in
# order to dispatch on Flash Attention 2. This feature is not compatible with static cache, as SDPA will fail
# to infer the attention mask.
past_seen_tokens = past_key_values.get_seq_length() if past_key_values is not None else 0
# When output attentions is True, sdpa implementation's forward method calls the eager implementation's forward
if self.config._attn_implementation == "sdpa" and not output_attentions:
if AttentionMaskConverter._ignore_causal_mask_sdpa(
attention_mask,
inputs_embeds=input_tensor,
past_key_values_length=past_seen_tokens,
is_training=self.training,
):
return None
dtype, device = input_tensor.dtype, input_tensor.device
sequence_length = input_tensor.shape[1]
target_length = (
attention_mask.shape[-1]
if isinstance(attention_mask, torch.Tensor)
else past_seen_tokens + sequence_length + 1
)
# In case the provided `attention` mask is 2D, we generate a causal mask here (4D).
causal_mask = self._prepare_4d_causal_attention_mask_with_cache_position(
attention_mask,
sequence_length=sequence_length,
target_length=target_length,
dtype=dtype,
device=device,
cache_position=cache_position,
batch_size=input_tensor.shape[0],
)
if (
self.config._attn_implementation == "sdpa"
and attention_mask is not None
and attention_mask.device.type in ["cuda", "xpu"]
and not output_attentions
):
# Attend to all tokens in fully masked rows in the causal_mask, for example the relevant first rows when
# using left padding. This is required by F.scaled_dot_product_attention memory-efficient attention path.
# Details: https://github.com/pytorch/pytorch/issues/110213
min_dtype = torch.finfo(dtype).min
causal_mask = AttentionMaskConverter._unmask_unattended(causal_mask, min_dtype)
return causal_mask
@staticmethod
def _prepare_4d_causal_attention_mask_with_cache_position(
attention_mask: torch.Tensor,
sequence_length: int,
target_length: int,
dtype: torch.dtype,
device: torch.device,
cache_position: torch.Tensor,
batch_size: int,
**kwargs,
):
"""
Creates a causal 4D mask of shape `(batch_size, 1, query_length, key_value_length)` from a 2D mask of shape
`(batch_size, key_value_length)`, or if the input `attention_mask` is already 4D, do nothing.
Args:
attention_mask (`torch.Tensor`):
A 2D attention mask of shape `(batch_size, key_value_length)` or a 4D attention mask of shape
`(batch_size, 1, query_length, key_value_length)`.
sequence_length (`int`):
The sequence length being processed.
target_length (`int`):
The target length: when generating with static cache, the mask should be as long as the static cache,
to account for the 0 padding, the part of the cache that is not filled yet.
dtype (`torch.dtype`):
The dtype to use for the 4D attention mask.
device (`torch.device`):
The device to place the 4D attention mask on.
cache_position (`torch.Tensor`):
Indices depicting the position of the input sequence tokens in the sequence.
batch_size (`torch.Tensor`):
Batch size.
"""
if attention_mask is not None and attention_mask.dim() == 4:
# In this case we assume that the mask comes already in inverted form and requires no inversion or slicing.
causal_mask = attention_mask
else:
min_dtype = torch.finfo(dtype).min
causal_mask = torch.full(
(sequence_length, target_length), fill_value=min_dtype, dtype=dtype, device=device
)
if sequence_length != 1:
causal_mask = torch.triu(causal_mask, diagonal=1)
causal_mask *= torch.arange(target_length, device=device) > cache_position.reshape(-1, 1)
causal_mask = causal_mask[None, None, :, :].expand(batch_size, 1, -1, -1)
if attention_mask is not None:
causal_mask = causal_mask.clone() # copy to contiguous memory for in-place edit
mask_length = attention_mask.shape[-1]
padding_attention_mask = (attention_mask[:, None, None, :] == attention_mask[:, None, :, None])[
:, :, -sequence_length:, :
].to(dtype)
padding_mask = causal_mask[:, :, :, :mask_length] + padding_attention_mask
padding_mask = padding_mask == 0
causal_mask[:, :, :, :mask_length] = causal_mask[:, :, :, :mask_length].masked_fill(
padding_mask, min_dtype
)
return causal_mask
def _update_mamba_mask(self, attention_mask, cache_position):
"""
No need for zeroing states when
1. Cached forward
2. Attending to all inputs
"""
mamba_mask = attention_mask
if cache_position[0] > 0 or (attention_mask is not None and torch.all(attention_mask == 1)):
mamba_mask = None
return mamba_mask
class BambaForCausalLM(BambaPreTrainedModel, GenerationMixin):
_tied_weights_keys = ["lm_head.weight"]
_tp_plan = {"lm_head": "colwise_rep"}
_pp_plan = {"lm_head": (["hidden_states"], ["logits"])}
def __init__(self, config):
super().__init__(config)
self.model = BambaModel(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 get_input_embeddings(self):
return self.model.embed_tokens
def set_input_embeddings(self, value):
self.model.embed_tokens = value
def get_output_embeddings(self):
return self.lm_head
def set_output_embeddings(self, new_embeddings):
self.lm_head = new_embeddings
def set_decoder(self, decoder):
self.model = decoder
def get_decoder(self):
return self.model
@can_return_tuple
@deprecate_kwarg("num_logits_to_keep", version="4.50", new_name="logits_to_keep")
@add_start_docstrings_to_model_forward(BAMBA_INPUTS_DOCSTRING)
@replace_return_docstrings(output_type=CausalLMOutputWithPast, config_class=_CONFIG_FOR_DOC)
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[HybridMambaAttentionDynamicCache] = None,
inputs_embeds: Optional[torch.FloatTensor] = None,
labels: Optional[torch.LongTensor] = None,
use_cache: Optional[bool] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
cache_position: Optional[torch.LongTensor] = None,
logits_to_keep: Union[int, torch.Tensor] = 0,
**kwargs,
) -> 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]`.
logits_to_keep (`int` or `torch.Tensor`, *optional*):
If an `int`, compute logits for the last `logits_to_keep` tokens. If `0`, calculate logits for all
`input_ids` (special case). Only last token logits are needed for generation, and calculating them only for that
token can save memory, which becomes pretty significant for long sequences or large vocabulary size.
If a `torch.Tensor`, must be 1D corresponding to the indices to keep in the sequence length dimension.
This is useful when using packed tensor format (single dimension for batch and sequence length).
Returns:
Example:
```python
>>> from transformers import AutoTokenizer, BambaForCausalLM
>>> model = BambaForCausalLM.from_pretrained("...")
>>> tokenizer = AutoTokenizer.from_pretrained("...")
>>> 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."
```"""
output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
)
# 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,
output_attentions=output_attentions,
output_hidden_states=output_hidden_states,
cache_position=cache_position,
**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, :])
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,
)
def prepare_inputs_for_generation(
self,
input_ids,
past_key_values=None,
attention_mask=None,
inputs_embeds=None,
cache_position=None,
position_ids=None,
use_cache=True,
**kwargs,
):
# Overwitten -- has a unique cache type, `HybridMambaAttentionDynamicCache`
empty_past_kv = past_key_values is None
# If we have cache: let's slice `input_ids` through `cache_position`, to keep only the unprocessed tokens
# Exception 1: when passing input_embeds, input_ids may be missing entries
# Exception 2: some generation methods do special slicing of input_ids, so we don't need to do it here
# Exception 3: with synced GPUs cache_position may go out of bounds, but we only want dummy token in that case.
# (we can't check exception 3 while compiling)
if not empty_past_kv:
if (
inputs_embeds is not None # Exception 1
or cache_position[-1] >= input_ids.shape[1] # Exception 3
):
input_ids = input_ids[:, -cache_position.shape[0] :]
elif input_ids.shape[1] != cache_position.shape[0]: # Default case (the "else", a no op, is Exception 2)
input_ids = input_ids[:, cache_position]
else:
past_key_values = HybridMambaAttentionDynamicCache(
self.config, input_ids.shape[0], self.dtype, device=self.device
)
if attention_mask is not None and position_ids is None:
# create position_ids on the fly for batch generation
position_ids = attention_mask.long().cumsum(-1) - 1
position_ids.masked_fill_(attention_mask == 0, 1)
if not empty_past_kv:
position_ids = position_ids[:, -input_ids.shape[1] :]
# if `inputs_embeds` are passed, we only want to use them in the 1st generation step
if inputs_embeds is not None and empty_past_kv:
model_inputs = {"inputs_embeds": inputs_embeds}
else:
model_inputs = {"input_ids": input_ids.contiguous()} # `contiguous()` needed for compilation use cases
model_inputs.update(
{
"position_ids": position_ids,
"past_key_values": past_key_values,
"use_cache": use_cache,
"attention_mask": attention_mask,
"logits_to_keep": self.config.num_logits_to_keep,
"cache_position": cache_position,
}
)
return model_inputs
__all__ = ["BambaModel", "BambaForCausalLM", "BambaPreTrainedModel"]