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fla2/models/linear_attn/configuration_linear_attn.py

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+# -*- coding: utf-8 -*-
+
+from typing import Optional
+
+from transformers.configuration_utils import PretrainedConfig
+
+
+class LinearAttentionConfig(PretrainedConfig):
+
+    model_type = 'linear_attn'
+    keys_to_ignore_at_inference = ['past_key_values']
+
+    def __init__(
+        self,
+        vocab_size: int = 32000,
+        hidden_size: int = 2048,
+        expand_k: int = 1,
+        expand_v: int = 1,
+        hidden_ratio: Optional[int] = 4,
+        intermediate_size: Optional[int] = None,
+        num_hidden_layers: int = 24,
+        num_heads: int = 4,
+        num_kv_heads: Optional[int] = None,
+        attn_mode: str = "fused_chunk",
+        feature_map: str = "elementwise_product",
+        tie_feature_map_qk: bool = False,
+        norm_q: bool = False,
+        norm_k: bool = False,
+        norm_feature_map: bool = False,
+        hidden_act: str = "swish",
+        max_position_embeddings: int = 2048,
+        elementwise_affine: Optional[bool] = True,
+        norm_eps: float = 1e-6,
+        use_cache: bool = True,
+        pad_token_id: int = None,
+        bos_token_id: int = 1,
+        eos_token_id: int = 2,
+        tie_word_embeddings: bool = False,
+        initializer_range: float = 0.02,
+        fuse_cross_entropy: bool = True,
+        **kwargs
+    ):
+        self.vocab_size = vocab_size
+        self.max_position_embeddings = max_position_embeddings
+        self.hidden_size = hidden_size
+        self.expand_k = expand_k
+        self.expand_v = expand_v
+        self.hidden_ratio = hidden_ratio
+        self.intermediate_size = intermediate_size
+        self.num_hidden_layers = num_hidden_layers
+        self.num_heads = num_heads
+        self.num_kv_heads = num_kv_heads
+        self.attn_mode = attn_mode
+        self.feature_map = feature_map
+        self.tie_feature_map_qk = tie_feature_map_qk
+        self.norm_q = norm_q
+        self.norm_k = norm_k
+        self.norm_feature_map = norm_feature_map
+        self.hidden_act = hidden_act
+        self.elementwise_affine = elementwise_affine
+        self.norm_eps = norm_eps
+        self.use_cache = use_cache
+        self.initializer_range = initializer_range
+        self.fuse_cross_entropy = fuse_cross_entropy
+
+        super().__init__(
+            pad_token_id=pad_token_id,
+            bos_token_id=bos_token_id,
+            eos_token_id=eos_token_id,
+            tie_word_embeddings=tie_word_embeddings,
+            **kwargs,
+        )

fla2/models/mamba/__init__.py

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+# -*- coding: utf-8 -*-
+
+from transformers import AutoConfig, AutoModel, AutoModelForCausalLM
+
+from fla.models.mamba.configuration_mamba import MambaConfig
+from fla.models.mamba.modeling_mamba import (MambaBlock, MambaForCausalLM,
+                                             MambaModel)
+
+AutoConfig.register(MambaConfig.model_type, MambaConfig, True)
+AutoModel.register(MambaConfig, MambaModel, True)
+AutoModelForCausalLM.register(MambaConfig, MambaForCausalLM, True)
+
+
+__all__ = ['MambaConfig', 'MambaForCausalLM', 'MambaModel', 'MambaBlock']

fla2/models/mamba/modeling_mamba.py

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+# coding=utf-8
+# Copyright 2024 state-spaces/mamba org and HuggingFace Inc. team.
+#
+# 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.
+"""PyTorch MAMBA model."""
+
+import math
+from dataclasses import dataclass
+from typing import Any, Dict, Optional, Tuple, Union
+
+import torch
+import torch.utils.checkpoint
+from torch import nn
+from transformers.activations import ACT2FN
+from transformers.modeling_utils import PreTrainedModel
+from transformers.utils import ModelOutput, logging
+
+from fla.models.mamba.configuration_mamba import MambaConfig
+from fla.modules import FusedCrossEntropyLoss, RMSNorm
+
+logger = logging.get_logger(__name__)
+
+try:
+    from mamba_ssm.ops.selective_scan_interface import (mamba_inner_fn,
+                                                        selective_scan_fn)
+    from mamba_ssm.ops.triton.selective_state_update import \
+        selective_state_update
+except ImportError:
+    selective_state_update, selective_scan_fn, mamba_inner_fn = None, None, None
+
+try:
+    from causal_conv1d import causal_conv1d_fn, causal_conv1d_update
+except ImportError:
+    causal_conv1d_update, causal_conv1d_fn = None, None
+
+is_fast_path_available = all(
+    (selective_state_update, selective_scan_fn, causal_conv1d_fn, causal_conv1d_update, mamba_inner_fn)
+)
+
+
+class MambaCache:
+    def __init__(self, config, batch_size, dtype=torch.float16, device=None):
+        self.seqlen_offset = 0
+        self.dtype = dtype
+        intermediate_size = config.intermediate_size
+        ssm_state_size = config.state_size
+        conv_kernel_size = config.conv_kernel
+
+        self.conv_states = {
+            i: torch.zeros(batch_size, intermediate_size, conv_kernel_size, device=device, dtype=dtype)
+            for i in range(config.num_hidden_layers)
+        }
+        self.ssm_states = {
+            i: torch.zeros(batch_size, intermediate_size, ssm_state_size, device=device, dtype=dtype)
+            for i in range(config.num_hidden_layers)
+        }
+
+
+class MambaMixer(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)
+    """
+
+    def __init__(self, config, layer_idx):
+        super().__init__()
+        self.hidden_size = config.hidden_size
+        self.ssm_state_size = config.state_size
+        self.conv_kernel_size = config.conv_kernel
+        self.intermediate_size = config.intermediate_size
+        self.time_step_rank = config.time_step_rank
+        self.layer_idx = layer_idx
+        self.use_conv_bias = config.use_conv_bias
+        self.conv1d = nn.Conv1d(
+            in_channels=self.intermediate_size,
+            out_channels=self.intermediate_size,
+            bias=config.use_conv_bias,
+            kernel_size=config.conv_kernel,
+            groups=self.intermediate_size,
+            padding=config.conv_kernel - 1,
+        )
+
+        self.activation = config.hidden_act
+        self.act = ACT2FN[config.hidden_act]
+
+        # projection of the input hidden states
+        self.in_proj = nn.Linear(self.hidden_size, self.intermediate_size * 2, bias=config.use_bias)
+        # selective projection used to make dt, B and C input dependant
+        self.x_proj = nn.Linear(self.intermediate_size, self.time_step_rank + self.ssm_state_size * 2, bias=False)
+        # time step projection (discretization)
+        self.dt_proj = nn.Linear(self.time_step_rank, self.intermediate_size, bias=True)
+
+        # 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.ssm_state_size + 1, dtype=torch.float32)[None, :]
+        A = A.expand(self.intermediate_size, -1).contiguous()
+
+        self.A_log = nn.Parameter(torch.log(A))
+        self.D = nn.Parameter(torch.ones(self.intermediate_size))
+        self.out_proj = nn.Linear(self.intermediate_size, self.hidden_size, bias=config.use_bias)
+        self.use_bias = config.use_bias
+
+        if not is_fast_path_available:
+            logger.warning_once(
+                "The fast path is not available because on of "
+                "`(selective_state_update, selective_scan_fn, causal_conv1d_fn, causal_conv1d_update, mamba_inner_fn)`"
+                " 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"
+            )
+
+    def cuda_kernels_forward(self, hidden_states: torch.Tensor, cache_params: Optional[MambaCache] = None):
+        # 1. Gated MLP's linear projection
+        projected_states = self.in_proj(hidden_states).transpose(1, 2)
+
+        if self.training and cache_params is None:  # Doesn't support outputting the states -> used for training
+            contextualized_states = mamba_inner_fn(
+                projected_states,
+                self.conv1d.weight,
+                self.conv1d.bias if self.use_conv_bias else None,
+                self.x_proj.weight,
+                self.dt_proj.weight,
+                self.out_proj.weight,
+                self.out_proj.bias.float() if self.use_bias else None,
+                -torch.exp(self.A_log.float()),
+                None,  # input-dependent B
+                None,  # input-dependent C
+                self.D.float(),
+                delta_bias=self.dt_proj.bias.float(),
+                delta_softplus=True,
+            )
+
+        else:
+            hidden_states, gate = projected_states.chunk(2, dim=1)
+
+            # 2. Convolution sequence transformation
+            conv_weights = self.conv1d.weight.view(self.conv1d.weight.size(0), self.conv1d.weight.size(2))
+            if cache_params is not None and cache_params.seqlen_offset > 0:
+                hidden_states = causal_conv1d_update(
+                    hidden_states.squeeze(-1),
+                    cache_params.conv_states[self.layer_idx],
+                    conv_weights,
+                    self.conv1d.bias,
+                    self.activation,
+                )
+                hidden_states = hidden_states.unsqueeze(-1)
+            else:
+                if cache_params is not None:
+                    conv_states = nn.functional.pad(
+                        hidden_states, (self.conv_kernel_size - hidden_states.shape[-1], 0)
+                    )
+                    cache_params.conv_states[self.layer_idx].copy_(conv_states)
+                hidden_states = causal_conv1d_fn(
+                    hidden_states, conv_weights, self.conv1d.bias, activation=self.activation
+                )
+
+            # 3. State Space Model sequence transformation
+            # 3.a. input varying initialization of time_step, B and C
+            ssm_parameters = self.x_proj(hidden_states.transpose(1, 2))
+            time_step, B, C = torch.split(
+                ssm_parameters, [self.time_step_rank, self.ssm_state_size, self.ssm_state_size], dim=-1
+            )
+            discrete_time_step = self.dt_proj.weight @ time_step.transpose(1, 2)
+
+            A = -torch.exp(self.A_log.float())
+            # 3.c perform the recurrence y ← SSM(A, B, C)(x)
+            time_proj_bias = self.dt_proj.bias.float() if hasattr(self.dt_proj, "bias") else None
+            if cache_params is not None and cache_params.seqlen_offset > 0:
+                scan_outputs = selective_state_update(
+                    cache_params.ssm_states[self.layer_idx],
+                    hidden_states[..., 0],
+                    discrete_time_step[..., 0],
+                    A,
+                    B[:, 0],
+                    C[:, 0],
+                    self.D,
+                    gate[..., 0],
+                    time_proj_bias,
+                    dt_softplus=True,
+                ).unsqueeze(-1)
+            else:
+                scan_outputs, ssm_state = selective_scan_fn(
+                    hidden_states,
+                    discrete_time_step,
+                    A,
+                    B.transpose(1, 2),
+                    C.transpose(1, 2),
+                    self.D.float(),
+                    gate,
+                    time_proj_bias,
+                    delta_softplus=True,
+                    return_last_state=True,
+                )
+                if ssm_state is not None and cache_params is not None:
+                    cache_params.ssm_states[self.layer_idx].copy_(ssm_state)
+
+            # 4. Final linear projection
+            contextualized_states = self.out_proj(scan_outputs.transpose(1, 2))
+        return contextualized_states
+
+    # fmt: off
+    def slow_forward(self, input_states, cache_params: Optional[MambaCache] = None):
+        batch_size, seq_len, _ = input_states.shape
+        dtype = input_states.dtype
+        # 1. Gated MLP's linear projection
+        # [batch, 2 * intermediate_size, seq_len]
+        projected_states = self.in_proj(input_states).transpose(1, 2)
+        hidden_states, gate = projected_states.chunk(2, dim=1)
+
+        # 2. Convolution sequence transformation
+        if cache_params is not None:
+            ssm_state = cache_params.ssm_states[self.layer_idx].clone()
+            if cache_params.seqlen_offset > 0:
+                # [batch, intermediate_size, conv_kernel_size]
+                conv_state = cache_params.conv_states[self.layer_idx]
+                conv_state = torch.roll(conv_state, shifts=-1, dims=-1)
+                conv_state[:, :, -1] = hidden_states[:, :, 0]
+                cache_params.conv_states[self.layer_idx].copy_(conv_state)
+                hidden_states = torch.sum(conv_state * self.conv1d.weight[:, 0, :], dim=-1)
+                if self.use_conv_bias:
+                    hidden_states += self.conv1d.bias
+                # [batch, intermediate_size, 1] : decoding
+                hidden_states = self.act(hidden_states).to(dtype).unsqueeze(-1)
+            else:
+                conv_state = nn.functional.pad(
+                    hidden_states,
+                    (self.conv_kernel_size - hidden_states.shape[-1], 0)
+                )
+                cache_params.conv_states[self.layer_idx].copy_(conv_state)
+                # [batch, intermediate_size, seq_len]
+                hidden_states = self.act(self.conv1d(hidden_states)[..., :seq_len])
+        else:
+            ssm_state = torch.zeros(
+                (batch_size, self.intermediate_size, self.ssm_state_size),
+                device=hidden_states.device, dtype=dtype
+            )
+            # [batch, intermediate_size, seq_len]
+            hidden_states = self.act(self.conv1d(hidden_states)[..., :seq_len])
+
+        # 3. State Space Model sequence transformation
+        # 3.a. Selection:  [batch, seq_len, self.time_step_rank + self.ssm_state_size * 2]
+        ssm_parameters = self.x_proj(hidden_states.transpose(1, 2))
+        time_step, B, C = torch.split(
+            ssm_parameters, [self.time_step_rank, self.ssm_state_size, self.ssm_state_size], dim=-1
+        )
+        # [batch, seq_len, intermediate_size]
+        discrete_time_step = self.dt_proj(time_step)
+        # [batch, intermediate_size, seq_len]
+        discrete_time_step = nn.functional.softplus(discrete_time_step).transpose(1, 2)
+
+        # 3.b. Discretization: B and C to [batch, seq_len, intermediate_size, ssm_state_size] (SRAM)
+        # [intermediate_size, ssm_state_size]
+        A = -torch.exp(self.A_log.float())
+        # [batch, intermediate_size, seq_len, ssm_state_size]
+        discrete_A = torch.exp(A[None, :, None, :] * discrete_time_step[:, :, :, None])
+        # [batch, intermediade_size, seq_len, ssm_state_size]
+        discrete_B = discrete_time_step[:, :, :, None] * B[:, None, :, :].float()
+        deltaB_u = discrete_B * hidden_states[:, :, :, None].float()
+
+        # 3.c perform the recurrence y ← SSM(A, B, C)(x)
+        scan_outputs = []
+        for i in range(seq_len):
+            # [batch, intermediade_size, ssm_state]
+            ssm_state = discrete_A[:, :, i, :] * ssm_state + deltaB_u[:, :, i, :]
+            # [batch, intermediade_size, 1]
+            scan_output = torch.matmul(ssm_state.to(dtype), C[:, i, :].unsqueeze(-1))
+            scan_outputs.append(scan_output[:, :, 0])
+        # [batch, seq_len, intermediade_size]
+        scan_output = torch.stack(scan_outputs, dim=-1)
+        scan_output = scan_output + (hidden_states * self.D[None, :, None])
+        scan_output = (scan_output * self.act(gate))
+
+        if cache_params is not None:
+            cache_params.ssm_states[self.layer_idx].copy_(ssm_state)
+
+        # 4. Final linear projection
+        # [batch, seq_len, hidden_size]
+        contextualized_states = self.out_proj(scan_output.transpose(1, 2))
+        return contextualized_states
+    # fmt: on
+
+    def forward(self, hidden_states, cache_params: Optional[MambaCache] = None):
+        if is_fast_path_available and "cuda" in self.x_proj.weight.device.type:
+            return self.cuda_kernels_forward(hidden_states, cache_params)
+        return self.slow_forward(hidden_states, cache_params)
+
+
+class MambaBlock(nn.Module):
+    def __init__(self, config, layer_idx):
+        super().__init__()
+        self.config = config
+        self.layer_idx = layer_idx
+        self.residual_in_fp32 = config.residual_in_fp32
+        self.norm = RMSNorm(config.hidden_size, eps=config.layer_norm_epsilon)
+        self.mixer = MambaMixer(config, layer_idx=layer_idx)
+
+    def forward(self, hidden_states, cache_params: Optional[MambaCache] = None):
+        residual = hidden_states
+        hidden_states = self.norm(hidden_states)
+        # if self.residual_in_fp32:
+        #     residual = residual.to(torch.float32)
+        hidden_states = self.mixer(hidden_states, cache_params=cache_params)
+        hidden_states = residual + hidden_states
+        return hidden_states
+
+
+class MambaPreTrainedModel(PreTrainedModel):
+    """
+    An abstract class to handle weights initialization and a simple interface for downloading and loading pretrained
+    models.
+    """
+
+    config_class = MambaConfig
+    base_model_prefix = "backbone"
+    _no_split_modules = ["MambaBlock"]
+    supports_gradient_checkpointing = True
+
+    def _init_weights(self, module):
+        """Initialize the weights."""
+        if isinstance(module, MambaMixer):
+            module.A_log._no_weight_decay = True
+            module.D._no_weight_decay = True
+
+            dt_init_std = self.config.time_step_rank**-0.5 * self.config.time_step_scale
+            if self.config.time_step_init_scheme == "constant":
+                nn.init.constant_(module.dt_proj.weight, dt_init_std)
+            elif self.config.time_step_init_scheme == "random":
+                nn.init.uniform_(module.dt_proj.weight, -dt_init_std, dt_init_std)
+
+            dt = torch.exp(
+                torch.rand(self.config.intermediate_size)
+                * (math.log(self.config.time_step_max) - math.log(self.config.time_step_min))
+                + math.log(self.config.time_step_min)
+            ).clamp(min=self.config.time_step_floor)
+            # # Inverse of softplus: https://github.com/pytorch/pytorch/issues/72759
+            inv_dt = dt + torch.log(-torch.expm1(-dt))
+            with torch.no_grad():
+                module.dt_proj.bias.copy_(inv_dt)
+            module.dt_proj.bias._no_reinit = True
+
+        if isinstance(module, nn.Linear):
+            if module.bias is not None:
+                if not getattr(module.bias, "_no_reinit", False):
+                    nn.init.zeros_(module.bias)
+        elif isinstance(module, nn.Embedding):
+            nn.init.normal_(module.weight, std=self.config.initializer_range)
+
+        if self.config.rescale_prenorm_residual:
+            # Reinitialize selected weights subject to the OpenAI GPT-2 Paper Scheme:
+            #   > A modified initialization which accounts for the accumulation on the residual path with model depth. Scale
+            #   > the weights of residual layers at initialization by a factor of 1/√N where N is the # of residual layers.
+            #   >   -- GPT-2 :: https://openai.com/blog/better-language-models/
+            #
+            # Reference (Megatron-LM): https://github.com/NVIDIA/Megatron-LM/blob/main/megatron/model/gpt_model.py
+            for name, p in module.named_parameters():
+                if name in ["out_proj.weight"]:
+                    # Special Scaled Initialization --> There are 2 Layer Norms per Transformer Block
+                    # Following Pytorch init, except scale by 1/sqrt(2 * n_layer)
+                    # We need to reinit p since this code could be called multiple times
+                    # Having just p *= scale would repeatedly scale it down
+                    nn.init.kaiming_uniform_(p, a=math.sqrt(5))
+                    with torch.no_grad():
+                        p /= math.sqrt(self.config.num_layers)
+
+
+@dataclass
+class MambaOutput(ModelOutput):
+    """
+    Class for the MAMBA model outputs.
+
+    Args:
+        last_hidden_state (`torch.FloatTensor` of shape `(batch_size, sequence_length, hidden_size)`):
+            Sequence of hidden-states at the output of the last layer of the model.
+        cache_params (`MambaCache`):
+            The state of the model at the last time step. Can be used in a forward method with the next `input_ids` to
+            avoid providing the old `input_ids`.
+
+            Includes both the State space model state matrices after the selective scan, and the Convolutional states
+        hidden_states (`tuple(torch.FloatTensor)`, *optional*,
+            returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
+            Tuple of `torch.FloatTensor` (one for the output of the embeddings, if the model has an embedding layer, +
+            one for the output of each layer) of shape `(batch_size, sequence_length, hidden_size)`.
+
+            Hidden-states of the model at the output of each layer plus the optional initial embedding outputs.
+    """
+
+    last_hidden_state: Optional[torch.FloatTensor] = None
+    cache_params: Optional[MambaCache] = None
+    hidden_states: Optional[Tuple[torch.FloatTensor]] = None
+
+
+@dataclass
+class MambaCausalLMOutput(ModelOutput):
+    """
+    Base class for causal language model (or autoregressive) outputs.
+
+    Args:
+        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.vocab_size)`):
+            Prediction scores of the language modeling head (scores for each vocabulary token before SoftMax).
+        cache_params (`MambaCache`):
+            The state of the model at the last time step. Can be used in a forward method with the next `input_ids` to
+            avoid providing the old `input_ids`.
+
+            Includes both the State space model state matrices after the selective scan, and the Convolutional states
+        hidden_states (`tuple(torch.FloatTensor)`, *optional*,
+            returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`):
+            Tuple of `torch.FloatTensor` (one for the output of the embeddings, if the model has an embedding layer, +
+            one for the output of each layer) of shape `(batch_size, sequence_length, hidden_size)`.
+
+            Hidden-states of the model at the output of each layer plus the optional initial embedding outputs.
+    """
+
+    loss: Optional[torch.FloatTensor] = None
+    logits: Optional[torch.FloatTensor] = None
+    cache_params: Optional[MambaCache] = None
+    hidden_states: Optional[Tuple[torch.FloatTensor]] = None
+
+
+class MambaModel(MambaPreTrainedModel):
+    def __init__(self, config):
+        super().__init__(config)
+
+        self.embeddings = nn.Embedding(config.vocab_size, config.hidden_size)
+        self.layers = nn.ModuleList([MambaBlock(config, layer_idx=idx) for idx in range(config.num_hidden_layers)])
+
+        self.gradient_checkpointing = False
+        self.norm_f = RMSNorm(config.hidden_size, eps=config.layer_norm_epsilon)
+        # Initialize weights and apply final processing
+        self.post_init()
+
+    def get_input_embeddings(self):
+        return self.embeddings
+
+    def set_input_embeddings(self, new_embeddings):
+        self.embeddings = new_embeddings
+
+    def forward(
+        self,
+        input_ids: Optional[torch.LongTensor] = None,
+        inputs_embeds: Optional[torch.LongTensor] = None,
+        cache_params: Optional[MambaCache] = None,
+        use_cache: Optional[bool] = None,
+        output_hidden_states: Optional[bool] = None,
+        return_dict: Optional[bool] = None,
+        **kwargs,  # `attention_mask` is passed by the tokenizer and we don't want it
+    ) -> Union[Tuple, MambaOutput]:
+        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 not self.training else False)
+        return_dict = return_dict if return_dict is not None else self.config.use_return_dict
+
+        if (input_ids is None) ^ (inputs_embeds is not None):  # ^ is python for xor
+            raise ValueError(
+                "You cannot specify both input_ids and inputs_embeds at the same time, and must specify either one"
+            )
+
+        if inputs_embeds is None:
+            inputs_embeds = self.embeddings(input_ids)
+
+        if self.gradient_checkpointing and self.training and use_cache:
+            use_cache = False
+
+        if cache_params is None and use_cache:
+            cache_params = MambaCache(
+                self.config, inputs_embeds.size(0), device=inputs_embeds.device, dtype=inputs_embeds.dtype
+            )
+
+        hidden_states = inputs_embeds
+        all_hidden_states = () if output_hidden_states else None
+        for mixer_block in self.layers:
+            if self.gradient_checkpointing and self.training:
+                hidden_states = self._gradient_checkpointing_func(mixer_block.__call__, hidden_states, cache_params)
+            else:
+                hidden_states = mixer_block(hidden_states, cache_params=cache_params)
+
+            if output_hidden_states:
+                all_hidden_states = all_hidden_states + (hidden_states,)
+
+        if use_cache:
+            cache_params.seqlen_offset += inputs_embeds.shape[1]
+
+        hidden_states = self.norm_f(hidden_states)
+
+        if output_hidden_states:
+            all_hidden_states = all_hidden_states + (hidden_states,)
+
+        if not return_dict:
+            return tuple(v for v in [hidden_states, cache_params, all_hidden_states] if v is not None)
+
+        return MambaOutput(
+            last_hidden_state=hidden_states,
+            cache_params=cache_params if use_cache else None,
+            hidden_states=all_hidden_states,
+        )
+
+
+class MambaForCausalLM(MambaPreTrainedModel):
+    _tied_weights_keys = ["lm_head.weight"]
+
+    def __init__(self, config):
+        super().__init__(config)
+        self.backbone = MambaModel(config)
+        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)
+        # Initialize weights and apply final processing
+        self.post_init()
+
+    def get_output_embeddings(self):
+        return self.lm_head
+
+    def set_output_embeddings(self, new_embeddings):
+        self.lm_head = new_embeddings
+
+    def get_input_embeddings(self):
+        return self.backbone.get_input_embeddings()
+
+    def set_input_embeddings(self, new_embeddings):
+        return self.backbone.set_input_embeddings(new_embeddings)
+
+    def _update_model_kwargs_for_generation(
+        self, outputs: ModelOutput, model_kwargs: Dict[str, Any], **kwargs
+    ) -> Dict[str, Any]:
+        model_kwargs["cache_params"] = outputs.get("cache_params", None)
+        return model_kwargs
+
+    def prepare_inputs_for_generation(
+        self, input_ids, cache_params: Optional[MambaCache] = None, inputs_embeds=None, attention_mask=None, **kwargs
+    ):
+        # only last token for inputs_ids if the state is passed along.
+        if cache_params is not None:
+            input_ids = input_ids[:, -1].unsqueeze(-1)
+
+        if inputs_embeds is not None and cache_params is None:
+            model_inputs = {"inputs_embeds": inputs_embeds}
+        else:
+            model_inputs = {"input_ids": input_ids}
+
+        model_inputs["cache_params"] = cache_params
+        return model_inputs
+
+    def forward(
+        self,
+        input_ids: Optional[torch.LongTensor] = None,
+        attention_mask: Optional[torch.Tensor] = None,  # noqa
+        inputs_embeds: Optional[torch.FloatTensor] = None,
+        cache_params: Optional[MambaCache] = None,
+        labels: Optional[torch.LongTensor] = None,
+        output_hidden_states: Optional[bool] = None,
+        return_dict: Optional[bool] = None,
+        use_cache: Optional[bool] = None,
+        **kwargs,  # for now we need this for generation
+    ) -> Union[Tuple, MambaCausalLMOutput]:
+        r"""
+        labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
+            Labels for language modeling. Note that the labels **are shifted** inside the model, i.e. you can set
+            `labels = input_ids` Indices are selected in `[-100, 0, ..., config.vocab_size]` All labels set to `-100`
+            are ignored (masked), the loss is only computed for labels in `[0, ..., config.vocab_size]`
+        """
+        return_dict = return_dict if return_dict is not None else self.config.use_return_dict
+
+        mamba_outputs = self.backbone(
+            input_ids,
+            cache_params=cache_params,
+            inputs_embeds=inputs_embeds,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+            use_cache=use_cache,
+        )
+        hidden_states = mamba_outputs[0]
+        logits = self.lm_head(hidden_states)
+
+        loss = None
+        if labels is not None:
+            if self.config.fuse_cross_entropy:
+                loss_fct = FusedCrossEntropyLoss(inplace_backward=True)
+            else:
+                loss_fct = nn.CrossEntropyLoss()
+            # Enable model parallelism
+            labels = labels.to(logits.device)
+            labels = torch.cat((labels[..., 1:], torch.full_like(labels[:, :1], loss_fct.ignore_index)), 1)
+            loss = loss_fct(logits.view(-1, self.config.vocab_size), labels.view(-1))
+
+        if not return_dict:
+            output = (logits,) + mamba_outputs[1:]
+            return (loss,) + output if loss is not None else output
+
+        return MambaCausalLMOutput(
+            loss=loss,
+            logits=logits,
+            cache_params=mamba_outputs.cache_params,
+            hidden_states=mamba_outputs.hidden_states,
+        )

fla2/models/mamba2/__init__.py

@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+
+from transformers import AutoConfig, AutoModel, AutoModelForCausalLM
+
+from fla.models.mamba2.configuration_mamba2 import Mamba2Config
+from fla.models.mamba2.modeling_mamba2 import Mamba2ForCausalLM, Mamba2Model
+
+AutoConfig.register(Mamba2Config.model_type, Mamba2Config, True)
+AutoModel.register(Mamba2Config, Mamba2Model, True)
+AutoModelForCausalLM.register(Mamba2Config, Mamba2ForCausalLM, True)
+
+
+__all__ = ['Mamba2Config', 'Mamba2ForCausalLM', 'Mamba2Model']