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configuration_switchllama.py

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+""" LLaMA model configuration"""
+
+# from ...configuration_utils import PretrainedConfig
+# from ...utils import logging
+from transformers.models.llama.configuration_llama import *
+
+
+logger = logging.get_logger(__name__)
+
+LLAMA_PRETRAINED_CONFIG_ARCHIVE_MAP = {}
+
+
+class SwitchLlamaConfig(PretrainedConfig):
+    r"""
+    This is the configuration class to store the configuration of a [`LlamaModel`]. It is used to instantiate an LLaMA
+    model according to the specified arguments, defining the model architecture. Instantiating a configuration with the
+    defaults will yield a similar configuration to that of the LLaMA-7B.
+
+    Configuration objects inherit from [`PretrainedConfig`] and can be used to control the model outputs. Read the
+    documentation from [`PretrainedConfig`] for more information.
+
+
+    Args:
+        vocab_size (`int`, *optional*, defaults to 32000):
+            Vocabulary size of the LLaMA model. Defines the number of different tokens that can be represented by the
+            `inputs_ids` passed when calling [`LlamaModel`]
+        hidden_size (`int`, *optional*, defaults to 4096):
+            Dimension of the hidden representations.
+        intermediate_size (`int`, *optional*, defaults to 11008):
+            Dimension of the MLP representations.
+        num_hidden_layers (`int`, *optional*, defaults to 32):
+            Number of hidden layers in the Transformer encoder.
+        num_attention_heads (`int`, *optional*, defaults to 32):
+            Number of attention heads for each attention layer in the Transformer encoder.
+        num_key_value_heads (`int`, *optional*):
+            This is the number of key_value heads that should be used to implement Grouped Query Attention. If
+            `num_key_value_heads=num_attention_heads`, the model will use Multi Head Attention (MHA), if
+            `num_key_value_heads=1 the model will use Multi Query Attention (MQA) otherwise GQA is used. When
+            converting a multi-head checkpoint to a GQA checkpoint, each group key and value head should be constructed
+            by meanpooling all the original heads within that group. For more details checkout [this
+            paper](https://arxiv.org/pdf/2305.13245.pdf). If it is not specified, will default to
+            `num_attention_heads`.
+        pretraining_tp (`int`, *optional*, defaults to `1`):
+            Experimental feature. Tensor parallelism rank used during pretraining. Please refer to [this
+            document](https://huggingface.co/docs/transformers/parallelism) to understand more about it. This value is
+            necessary to ensure exact reproducibility of the pretraining results. Please refer to [this
+            issue](https://github.com/pytorch/pytorch/issues/76232).
+        hidden_act (`str` or `function`, *optional*, defaults to `"silu"`):
+            The non-linear activation function (function or string) in the decoder.
+        max_position_embeddings (`int`, *optional*, defaults to 2048):
+            The maximum sequence length that this model might ever be used with. Llama 1 supports up to 2048 tokens,
+            Llama 2 up to 4096, CodeLlama up to 16384.
+        initializer_range (`float`, *optional*, defaults to 0.02):
+            The standard deviation of the truncated_normal_initializer for initializing all weight matrices.
+        rms_norm_eps (`float`, *optional*, defaults to 1e-12):
+            The epsilon used by the rms normalization layers.
+        use_cache (`bool`, *optional*, defaults to `True`):
+            Whether or not the model should return the last key/values attentions (not used by all models). Only
+            relevant if `config.is_decoder=True`.
+        tie_word_embeddings(`bool`, *optional*, defaults to `False`):
+            Whether to tie weight embeddings
+        rope_theta (`float`, *optional*, defaults to 10000.0):
+            The base period of the RoPE embeddings.
+        rope_scaling (`Dict`, *optional*):
+            Dictionary containing the scaling configuration for the RoPE embeddings. Currently supports two scaling
+            strategies: linear and dynamic. Their scaling factor must be an float greater than 1. The expected format
+            is `{"type": strategy name, "factor": scaling factor}`. When using this flag, don't update
+            `max_position_embeddings` to the expected new maximum. See the following thread for more information on how
+            these scaling strategies behave:
+            https://www.reddit.com/r/LocalLLaMA/comments/14mrgpr/dynamically_scaled_rope_further_increases/. This is an
+            experimental feature, subject to breaking API changes in future versions.
+
+        Example:
+
+    ```python
+    >>> from transformers import LlamaModel, LlamaConfig
+
+    >>> # Initializing a LLaMA llama-7b style configuration
+    >>> configuration = LlamaConfig()
+
+    >>> # Initializing a model from the llama-7b style configuration
+    >>> model = LlamaModel(configuration)
+
+    >>> # Accessing the model configuration
+    >>> configuration = model.config
+    ```"""
+    model_type = "switchllama"
+    keys_to_ignore_at_inference = ["past_key_values"]
+
+    def __init__(
+        self,
+        vocab_size=32000,
+        hidden_size=4096,
+        intermediate_size=11008,
+        num_hidden_layers=32,
+        num_attention_heads=32,
+        num_key_value_heads=None,
+        hidden_act="silu",
+        max_position_embeddings=2048,
+        initializer_range=0.02,
+        rms_norm_eps=1e-6,
+        use_cache=True,
+        pad_token_id=None,
+        bos_token_id=1,
+        eos_token_id=2,
+        pretraining_tp=1,
+        tie_word_embeddings=False,
+        rope_theta=10000.0,
+        rope_scaling=None,
+        # extra!
+        expert_capacity=64,
+        router_bias=False,
+        router_jitter_noise=0.01,
+        router_ignore_padding_tokens=False,
+        num_experts=8,
+        dropout_rate=0.01,
+        router_aux_loss_coef=0.001,
+        router_z_loss_coef=0.001,
+        **kwargs,
+    ):
+        self.router_aux_loss_coef=router_aux_loss_coef
+        self.router_z_loss_coef=router_z_loss_coef
+        self.dropout_rate = dropout_rate
+        self.num_experts = num_experts
+        self.router_ignore_padding_tokens = router_ignore_padding_tokens
+        self.router_jitter_noise = router_jitter_noise
+        self.router_bias = router_bias
+        self.expert_capacity = expert_capacity
+        self.vocab_size = vocab_size
+        self.max_position_embeddings = max_position_embeddings
+        self.hidden_size = hidden_size
+        self.intermediate_size = intermediate_size
+        self.num_hidden_layers = num_hidden_layers
+        self.num_attention_heads = num_attention_heads
+
+        # for backward compatibility
+        if num_key_value_heads is None:
+            num_key_value_heads = num_attention_heads
+
+        self.num_key_value_heads = num_key_value_heads
+        self.hidden_act = hidden_act
+        self.initializer_range = initializer_range
+        self.rms_norm_eps = rms_norm_eps
+        self.pretraining_tp = pretraining_tp
+        self.use_cache = use_cache
+        self.rope_theta = rope_theta
+        self.rope_scaling = rope_scaling
+        self._rope_scaling_validation()
+
+        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,
+        )
+
+    def _rope_scaling_validation(self):
+        """
+        Validate the `rope_scaling` configuration.
+        """
+        if self.rope_scaling is None:
+            return
+
+        if not isinstance(self.rope_scaling, dict) or len(self.rope_scaling) != 2:
+            raise ValueError(
+                "`rope_scaling` must be a dictionary with with two fields, `type` and `factor`, "
+                f"got {self.rope_scaling}"
+            )
+        rope_scaling_type = self.rope_scaling.get("type", None)
+        rope_scaling_factor = self.rope_scaling.get("factor", None)
+        if rope_scaling_type is None or rope_scaling_type not in ["linear", "dynamic"]:
+            raise ValueError(
+                f"`rope_scaling`'s type field must be one of ['linear', 'dynamic'], got {rope_scaling_type}"
+            )
+        if rope_scaling_factor is None or not isinstance(rope_scaling_factor, float) or rope_scaling_factor <= 1.0:
+            raise ValueError(f"`rope_scaling`'s factor field must be an float > 1, got {rope_scaling_factor}")

modeling_switchllama.py

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+# copyright idek
+
+from transformers.models.llama.modeling_llama import *
+from torch import nn
+import torch
+from configuration_switchllama import SwitchLlamaConfig
+
+
+def router_z_loss_func(router_logits: torch.Tensor) -> float:
+    r"""
+    Compute the router z-loss implemented in PyTorch.
+
+    The router z-loss was introduced in [Designing Effective Sparse Expert Models](https://arxiv.org/abs/2202.08906).
+    It encourages router logits to remain small in an effort to improve stability.
+
+    Args:
+        router_logits (`float`):
+            Input logits of shape [batch_size, sequence_length, num_experts]
+
+    Returns:
+        Scalar router z-loss.
+    """
+    num_groups, tokens_per_group, _ = router_logits.shape
+    log_z = torch.logsumexp(router_logits, dim=-1)
+    z_loss = log_z**2
+    return torch.sum(z_loss) / (num_groups * tokens_per_group)
+
+
+def load_balancing_loss_func(router_probs: torch.Tensor, expert_indices: torch.Tensor) -> float:
+    r"""
+    Computes auxiliary load balancing loss as in Switch Transformer - implemented in Pytorch.
+
+    See Switch Transformer (https://arxiv.org/abs/2101.03961) for more details. This function implements the loss
+    function presented in equations (4) - (6) of the paper. It aims at penalizing cases where the routing between
+    experts is too unbalanced.
+
+    Args:
+        router_probs (`torch.Tensor`):
+            Probability assigned to each expert per token. Shape: [batch_size, seqeunce_length, num_experts].
+        expert_indices (`torch.Tensor`):
+            Indices tensor of shape [batch_size, seqeunce_length] identifying the selected expert for a given token.
+
+    Returns:
+        The auxiliary loss.
+    """
+    num_experts = router_probs.shape[-1]
+
+    # cast the expert indices to int64, otherwise one-hot encoding will fail
+    if expert_indices.dtype != torch.int64:
+        expert_indices = expert_indices.to(torch.int64)
+
+    if len(expert_indices.shape) == 2:
+        expert_indices = expert_indices.unsqueeze(2)
+
+    expert_mask = torch.nn.functional.one_hot(expert_indices, num_experts)
+
+    # For a given token, determine if it was routed to a given expert.
+    expert_mask = torch.max(expert_mask, axis=-2).values
+
+    # cast to float32 otherwise mean will fail
+    expert_mask = expert_mask.to(torch.float32)
+    tokens_per_group_and_expert = torch.mean(expert_mask, axis=-2)
+
+    router_prob_per_group_and_expert = torch.mean(router_probs, axis=-2)
+    return torch.mean(tokens_per_group_and_expert * router_prob_per_group_and_expert) * (num_experts**2)
+
+
+# Copied from transformers.models.bart.modeling_bart._make_causal_mask
+def _make_causal_mask(
+    input_ids_shape: torch.Size, dtype: torch.dtype, device: torch.device, past_key_values_length: int = 0
+):
+    """
+    Make causal mask used for bi-directional self-attention.
+    """
+    bsz, tgt_len = input_ids_shape
+    mask = torch.full((tgt_len, tgt_len), torch.finfo(dtype).min, device=device)
+    mask_cond = torch.arange(mask.size(-1), device=device)
+    mask.masked_fill_(mask_cond < (mask_cond + 1).view(mask.size(-1), 1), 0)
+    mask = mask.to(dtype)
+
+    if past_key_values_length > 0:
+        mask = torch.cat([torch.zeros(tgt_len, past_key_values_length, dtype=dtype, device=device), mask], dim=-1)
+    return mask[None, None, :, :].expand(bsz, 1, tgt_len, tgt_len + past_key_values_length)
+
+def _expand_mask(mask: torch.Tensor, dtype: torch.dtype, tgt_len: Optional[int] = None):
+    """
+    Expands attention_mask from `[bsz, seq_len]` to `[bsz, 1, tgt_seq_len, src_seq_len]`.
+    """
+    bsz, src_len = mask.size()
+    tgt_len = tgt_len if tgt_len is not None else src_len
+
+    expanded_mask = mask[:, None, None, :].expand(bsz, 1, tgt_len, src_len).to(dtype)
+
+    inverted_mask = 1.0 - expanded_mask
+
+    return inverted_mask.masked_fill(inverted_mask.to(torch.bool), torch.finfo(dtype).min)
+
+
+
+class SwitchLlamaTop1Router(nn.Module):
+    """
+    Router using tokens choose top-1 experts assignment.
+
+    This router uses the same mechanism as in Switch Transformer (https://arxiv.org/abs/2101.03961) and V-MoE
+    (https://arxiv.org/abs/2106.05974): tokens choose their top experts. Items are sorted by router_probs and then
+    routed to their choice of expert until the expert's expert_capacity is reached. **There is no guarantee that each
+    token is processed by an expert**, or that each expert receives at least one token.
+
+    """
+
+    def __init__(self, config: SwitchLlamaConfig):
+        super().__init__()
+        self.num_experts = config.num_experts
+        self.expert_capacity = config.expert_capacity
+        self.classifier = nn.Linear(config.hidden_size, self.num_experts, bias=config.router_bias)
+        self.jitter_noise = config.router_jitter_noise
+        self.ignore_padding_tokens = config.router_ignore_padding_tokens
+        
+    def _compute_router_probabilities(self, hidden_states: torch.Tensor) -> Tuple[torch.Tensor, torch.Tensor]:
+        r"""
+        Computes router probabilities from input hidden states.
+
+        Args:
+            hidden_states (`torch.Tensor`):
+                (batch_size, sequence_length, hidden_dim) from which router probabilities are computed.
+        Returns:
+            router_probabilities (`torch.Tensor`):
+                Tensor of shape (batch_size, sequence_length, num_experts) corresponding to the probabilities for each
+                token and expert. Used for routing tokens to experts.
+            router_logits (`torch.Tensor`):
+                Logits tensor of shape (batch_size, sequence_length, num_experts) corresponding to raw router logits.
+                This is used later for computing router z-loss.
+        """
+        if self.jitter_noise > 0:
+            # Get the lower and upper bound of the uniform distribution
+            # Adapted from: https://stackoverflow.com/questions/44328530/how-to-get-a-uniform-distribution-in-a-range-r1-r2-in-pytorch
+            distrib_lower_bound = 1.0 - self.jitter_noise
+            distrib_upper_bound = 1.0 + self.jitter_noise
+
+            uniform_distrib = torch.rand(hidden_states.shape, device=hidden_states.device, dtype=hidden_states.dtype)
+            uniform_distrib = uniform_distrib * (distrib_lower_bound - distrib_upper_bound)
+
+            uniform_distrib = uniform_distrib + distrib_upper_bound
+            # Multiply the token inputs by the uniform distribution - adding some noise
+            hidden_states *= uniform_distrib
+
+        # Shape: [num_groups, tokens_per_group, num_experts]
+        router_logits = self.classifier(hidden_states)
+
+        # Apply Softmax
+        router_probabilities = nn.functional.softmax(router_logits, dim=-1)
+        return router_probabilities, router_logits
+        
+    def forward(self, hidden_states: torch.Tensor) -> Tuple:
+        r"""
+        Generic forward function for every Router class. Each Router expects to have the same input hidden states
+        (`hidden_states`) corresponding to the hidden states for each token, the `expert_capacity` corresponding to the
+        number of tokens the Router will send to each expert, some Routers can send up to few tokens to each expert.
+
+        Each Router works as the following: it expects the hidden states for each token, gets the `router_probs` and
+        `router_logits` from the `router_weights`. This will assign for each token, the raw probability to be assigned
+        to an expert. Then each Router class will have to define its own `_compute_routing_instructions`.
+
+        Args:
+            hidden_states (`torch.Tensor`) :
+                [num_groups, tokens_per_group, hidden_dim] inputs to send to experts.
+        Returns:
+            Tuple[`torch.Tensor`, `torch.Tensor`, `torch.Tensor`] Tuple containing the expert index, the router probs
+            and the router logits. The router probabilities and logits are required to compute the loss.
+        """
+        router_probs, router_logits = self._compute_router_probabilities(hidden_states)
+
+        expert_index = torch.argmax(router_probs, dim=-1)
+        expert_index = torch.nn.functional.one_hot(expert_index, num_classes=self.num_experts)
+
+        # Mask tokens outside expert capacity. Sum over each sequence
+        token_priority = torch.cumsum(expert_index, dim=-2)
+        # mask if the token routed to to the expert will overflow
+        expert_capacity_mask = token_priority <= self.expert_capacity
+        expert_index = expert_index * expert_capacity_mask
+
+        router_probs = torch.max(router_probs, dim=-1).values.unsqueeze(-1)
+        return expert_index, router_probs, router_logits
+
+class SwitchLlamaSparseMLP(nn.Module):
+    r"""
+    Implementation of the Switch Transformers Sparse MLP module.
+    """
+
+    def __init__(self, config: SwitchLlamaConfig, expert_class: nn.Module = LlamaMLP):
+        super().__init__()
+        # Step 1: Get the correct router according to its class
+        self.router = SwitchLlamaTop1Router(config)
+
+        # Step 2: Get the experts
+        self.experts = nn.ModuleDict()
+        for idx in range(config.num_experts):
+            self.experts[f"expert_{idx}"] = expert_class(config)
+
+    def forward(self, hidden_states):
+        r"""
+        Hold on, this will be slightly tricky to understand In the correct order, a MoE layer does the following:
+
+        1- Gets the `router_mask` from the router. The shape of the mask is `(batch_size, sequence_length, num_expert)`
+        and corresponds to the argmax of the `router_probs`. The probabilities are needed in the computation of the
+        hidden states : they are broadcasted to the hidden states values (can be interpreted as a scaling factor).
+
+        2- Dispatch the tokens to its associated experts. We do a classic for loop over the experts and assign for each
+        expert the corresponding hidden states.
+
+        """
+        # Step 1: Get the router_mask from the router as wel as the probabilities
+        router_mask, router_probs, router_logits = self.router(hidden_states)
+        expert_index = torch.argmax(router_mask, dim=-1)
+
+        # The routers introduced might not always map all the tokens, to a router, which means that some hidden states
+        # can be unchanged from one layer to another. That is why the hidden states are cloned before updating only the seleced ones.
+
+        next_states = hidden_states.clone()
+        for idx, expert in enumerate(self.experts.values()):
+            token_indices = router_mask[:, :, idx].bool()
+            next_states[token_indices] = expert(hidden_states[token_indices])
+
+        hidden_states = router_probs * next_states
+        return hidden_states, (router_logits, expert_index)
+
+class SwitchLlamaLayerFF(nn.Module):
+    r"""
+    Switch Transformers Feed Forward layer module. This is a wrapper around the Mixture of Experts module.
+
+    Parameters:
+        config : ([`SwitchTransformersConfig`]): 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.
+        is_sparse (`bool`):
+            Whether the MLP layer is a `Sparse` layer (contains a Mixture of Experts) or not
+    """
+
+    def __init__(self, config: SwitchLlamaConfig, is_sparse=True):
+        super().__init__()
+        self.is_sparse = is_sparse
+
+        # Check if it is a sparse layer, if not then it is a dense layer
+        if not self.is_sparse:
+            self.mlp = LlamaMLP(config)
+        else:
+            self.mlp = SwitchLlamaSparseMLP(config)
+
+        # self.layer_norm = LlamaRMSNorm(config.hidden_size, eps=config.rms_norm_eps)
+        self.dropout = nn.Dropout(config.dropout_rate)
+
+    def forward(self, hidden_states, output_router_logits=False):
+        # forwarded_states = self.layer_norm(hidden_states)
+        forwarded_states = self.mlp(hidden_states)
+
+        if isinstance(forwarded_states, tuple):
+            forwarded_states, router_tuple = forwarded_states
+        else:
+            router_tuple = None
+
+        output = hidden_states + self.dropout(forwarded_states)
+
+        if output_router_logits and router_tuple is not None:
+            output = (output, router_tuple)
+
+        return output
+
+class SwitchLlamaDecoderLayer(nn.Module):
+    def __init__(self, config: SwitchLlamaConfig):
+        super().__init__()
+        self.hidden_size = config.hidden_size
+        self.self_attn = LlamaAttention(config=config)
+        self.mlp = SwitchLlamaLayerFF(config)
+        self.input_layernorm = LlamaRMSNorm(config.hidden_size, eps=config.rms_norm_eps)
+        self.post_attention_layernorm = LlamaRMSNorm(config.hidden_size, eps=config.rms_norm_eps)
+
+    def forward(
+        self,
+        hidden_states: torch.Tensor,
+        attention_mask: Optional[torch.Tensor] = None,
+        position_ids: Optional[torch.LongTensor] = None,
+        past_key_value: Optional[Tuple[torch.Tensor]] = None,
+        output_attentions: Optional[bool] = False,
+        use_cache: Optional[bool] = False,
+        output_router_logits = True
+    ) -> 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, 1, tgt_len, src_len)` where padding elements are indicated by very large negative 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.
+            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`).
+            past_key_value (`Tuple(torch.FloatTensor)`, *optional*): cached past key and value projection states
+        """
+
+        residual = hidden_states
+
+        hidden_states = self.input_layernorm(hidden_states)
+
+        # Self Attention
+        hidden_states, self_attn_weights, present_key_value = 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,
+        )
+        hidden_states = residual + hidden_states
+
+        # Fully Connected
+        residual = hidden_states
+        hidden_states = self.post_attention_layernorm(hidden_states)
+        hidden_states = self.mlp(hidden_states, output_router_logits=output_router_logits)
+        if type(hidden_states)==tuple:
+            hidden_states, router_tuple = hidden_states
+        else:
+            router_tuple = (torch.tensor([0], device=hidden_states.device),)
+        hidden_states = residual + hidden_states
+
+        outputs = (hidden_states,)
+
+        if output_attentions:
+            outputs += (self_attn_weights,)
+
+        if use_cache:
+            outputs += (present_key_value,)
+
+        # if output_router_logits:
+        #     outputs += (router_tuple,)
+        return outputs + (router_tuple,)
+
+class SwitchLlamaPreTrainedModel(PreTrainedModel):
+    config_class = SwitchLlamaConfig
+    base_model_prefix = "model"
+    supports_gradient_checkpointing = True
+    _no_split_modules = ["SwitchLlamaDecoderLayer"]
+    _skip_keys_device_placement = "past_key_values"
+
+    def _init_weights(self, module):
+        std = self.config.initializer_range
+        if isinstance(module, nn.Linear):
+            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_()
+
+    def _set_gradient_checkpointing(self, module, value=False):
+        if isinstance(module, LlamaModel):
+            module.gradient_checkpointing = value
+
+
+class SwitchLlamaModel(SwitchLlamaPreTrainedModel):
+    """
+    Transformer decoder consisting of *config.num_hidden_layers* layers. Each layer is a [`LlamaDecoderLayer`]
+
+    Args:
+        config: SwitchLlamaConfig
+    """
+
+    def __init__(self, config: SwitchLlamaConfig):
+        super().__init__(config)
+        self.padding_idx = config.pad_token_id
+        self.vocab_size = config.vocab_size
+
+        self.embed_tokens = nn.Embedding(config.vocab_size, config.hidden_size, self.padding_idx)
+        self.layers = nn.ModuleList([SwitchLlamaDecoderLayer(config) for _ in range(config.num_hidden_layers)])
+        self.norm = LlamaRMSNorm(config.hidden_size, eps=config.rms_norm_eps)
+
+        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
+
+    # Copied from transformers.models.bart.modeling_bart.BartDecoder._prepare_decoder_attention_mask
+    def _prepare_decoder_attention_mask(self, attention_mask, input_shape, inputs_embeds, past_key_values_length):
+        # create causal mask
+        # [bsz, seq_len] -> [bsz, 1, tgt_seq_len, src_seq_len]
+        combined_attention_mask = None
+        if input_shape[-1] > 1:
+            combined_attention_mask = _make_causal_mask(
+                input_shape,
+                inputs_embeds.dtype,
+                device=inputs_embeds.device,
+                past_key_values_length=past_key_values_length,
+            )
+
+        if attention_mask is not None:
+            # [bsz, seq_len] -> [bsz, 1, tgt_seq_len, src_seq_len]
+            expanded_attn_mask = _expand_mask(attention_mask, inputs_embeds.dtype, tgt_len=input_shape[-1]).to(
+                inputs_embeds.device
+            )
+            combined_attention_mask = (
+                expanded_attn_mask if combined_attention_mask is None else expanded_attn_mask + combined_attention_mask
+            )
+
+        return combined_attention_mask
+
+    @add_start_docstrings_to_model_forward(LLAMA_INPUTS_DOCSTRING)
+    def forward(
+        self,
+        input_ids: torch.LongTensor = None,
+        attention_mask: Optional[torch.Tensor] = None,
+        position_ids: Optional[torch.LongTensor] = None,
+        past_key_values: Optional[List[torch.FloatTensor]] = None,
+        inputs_embeds: Optional[torch.FloatTensor] = None,
+        use_cache: Optional[bool] = None,
+        output_attentions: Optional[bool] = None,
+        output_hidden_states: Optional[bool] = None,
+        return_dict: Optional[bool] = None,
+        output_router_logits = False
+    ) -> Union[Tuple, 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
+
+        return_dict = return_dict if return_dict is not None else self.config.use_return_dict
+        all_router_probs = () if output_router_logits else None
+        # retrieve input_ids and inputs_embeds
+        if input_ids is not None and inputs_embeds is not None:
+            raise ValueError("You cannot specify both decoder_input_ids and decoder_inputs_embeds at the same time")
+        elif input_ids is not None:
+            batch_size, seq_length = input_ids.shape
+        elif inputs_embeds is not None:
+            batch_size, seq_length, _ = inputs_embeds.shape
+        else:
+            raise ValueError("You have to specify either decoder_input_ids or decoder_inputs_embeds")
+
+        seq_length_with_past = seq_length
+        past_key_values_length = 0
+
+        if past_key_values is not None:
+            past_key_values_length = past_key_values[0][0].shape[2]
+            seq_length_with_past = seq_length_with_past + past_key_values_length
+
+        if position_ids is None:
+            device = input_ids.device if input_ids is not None else inputs_embeds.device
+            position_ids = torch.arange(
+                past_key_values_length, seq_length + past_key_values_length, dtype=torch.long, device=device
+            )
+            position_ids = position_ids.unsqueeze(0).view(-1, seq_length)
+        else:
+            position_ids = position_ids.view(-1, seq_length).long()
+
+        if inputs_embeds is None:
+            inputs_embeds = self.embed_tokens(input_ids)
+        # embed positions
+        if attention_mask is None:
+            attention_mask = torch.ones(
+                (batch_size, seq_length_with_past), dtype=torch.bool, device=inputs_embeds.device
+            )
+        attention_mask = self._prepare_decoder_attention_mask(
+            attention_mask, (batch_size, seq_length), inputs_embeds, past_key_values_length
+        )
+
+        hidden_states = inputs_embeds
+
+        if self.gradient_checkpointing and self.training:
+            if use_cache:
+                logger.warning_once(
+                    "`use_cache=True` is incompatible with gradient checkpointing. Setting `use_cache=False`..."
+                )
+                use_cache = False
+
+        # decoder layers
+        all_hidden_states = () if output_hidden_states else None
+        all_self_attns = () if output_attentions else None
+        next_decoder_cache = () if use_cache else None
+
+        for idx, decoder_layer in enumerate(self.layers):
+            if output_hidden_states:
+                all_hidden_states += (hidden_states,)
+
+            past_key_value = past_key_values[idx] if past_key_values is not None else None
+
+            if self.gradient_checkpointing and self.training:
+
+                def create_custom_forward(module):
+                    def custom_forward(*inputs):
+                        # None for past_key_value
+                        return module(*inputs, past_key_value, output_attentions)
+
+                    return custom_forward
+
+                layer_outputs = torch.utils.checkpoint.checkpoint(
+                    create_custom_forward(decoder_layer),
+                    hidden_states,
+                    attention_mask,
+                    position_ids,
+                )
+            else:
+                layer_outputs = decoder_layer(
+                    hidden_states,
+                    attention_mask=attention_mask,
+                    position_ids=position_ids,
+                    past_key_value=past_key_value,
+                    output_attentions=output_attentions,
+                    use_cache=use_cache,
+                    output_router_logits=output_router_logits
+                )
+
+            hidden_states = layer_outputs[0]
+            router_probs = layer_outputs[-1]
+            
+            if use_cache:
+                next_decoder_cache += (layer_outputs[2 if output_attentions else 1],)
+
+            if output_attentions:
+                all_self_attns += (layer_outputs[1],)
+                
+            if output_router_logits:
+                all_router_probs = all_router_probs + (router_probs,)
+        hidden_states = self.norm(hidden_states)
+
+        # add hidden states from the last decoder layer
+        if output_hidden_states:
+            all_hidden_states += (hidden_states,)
+
+        next_cache = next_decoder_cache if use_cache else None
+        if not return_dict:
+            return tuple(v for v in [hidden_states, next_cache, all_hidden_states, all_self_attns] if v is not None)
+
+        from transformers.models.switch_transformers.modeling_switch_transformers import MoEModelOutputWithPastAndCrossAttentions
+        return MoEModelOutputWithPastAndCrossAttentions(
+            last_hidden_state=hidden_states,
+            past_key_values=next_cache,
+            hidden_states=all_hidden_states,
+            attentions=all_self_attns,
+            router_probs=all_router_probs,
+        )
+
+class SwitchLlamaForCausalLM(SwitchLlamaPreTrainedModel):
+    _tied_weights_keys = ["lm_head.weight"]
+
+    def __init__(self, config):
+        super().__init__(config)
+        self.model = SwitchLlamaModel(config)
+        self.vocab_size = config.vocab_size
+        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)
+
+        self.router_z_loss_coef = config.router_z_loss_coef
+        self.router_aux_loss_coef = config.router_aux_loss_coef
+        # Initialize weights and apply final processing
+        self.post_init()
+    def _unpack_router_logits(self, router_outputs):
+        total_router_logits = []
+        total_expert_indexes = []
+        for router_output in router_outputs:
+            if len(router_output[0].shape) > 1:
+                router_logits, expert_indexes = router_output
+                total_router_logits.append(router_logits)
+                total_expert_indexes.append(expert_indexes)
+        return torch.cat(total_router_logits, dim=1), torch.cat(total_expert_indexes, dim=1)
+
+
+    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
+
+    def forward(
+        self,
+        input_ids: torch.LongTensor = None,
+        attention_mask: Optional[torch.Tensor] = None,
+        position_ids: Optional[torch.LongTensor] = None,
+        past_key_values: Optional[List[torch.FloatTensor]] = 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,
+        return_dict: Optional[bool] = None,
+        output_router_logits = False,
+    ) -> Union[Tuple, CausalLMOutputWithPast]:
+        r"""
+        Args:
+            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]`.
+
+        Returns:
+
+        Example:
+
+        ```python
+        >>> from transformers import AutoTokenizer, LlamaForCausalLM
+
+        >>> model = LlamaForCausalLM.from_pretrained(PATH_TO_CONVERTED_WEIGHTS)
+        >>> tokenizer = AutoTokenizer.from_pretrained(PATH_TO_CONVERTED_TOKENIZER)
+
+        >>> 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
+        )
+        return_dict = return_dict if return_dict is not None else self.config.use_return_dict
+
+        # decoder outputs consists of (dec_features, layer_state, dec_hidden, dec_attn)
+        outputs = self.model(
+            input_ids=input_ids,
+            attention_mask=attention_mask,
+            position_ids=position_ids,
+            past_key_values=past_key_values,
+            inputs_embeds=inputs_embeds,
+            use_cache=use_cache,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states,
+            return_dict=return_dict,
+            output_router_logits=output_router_logits
+        )
+
+        hidden_states = outputs[0]
+        if self.config.pretraining_tp > 1:
+            lm_head_slices = self.lm_head.weight.split(self.vocab_size // self.config.pretraining_tp, dim=0)
+            logits = [F.linear(hidden_states, lm_head_slices[i]) for i in range(self.config.pretraining_tp)]
+            logits = torch.cat(logits, dim=-1)
+        else:
+            logits = self.lm_head(hidden_states)
+        logits = logits.float()
+
+        loss = None
+        decoder_z_loss = None
+        decoder_aux_loss = None
+
+        if output_router_logits:
+            decoder_router_logits, decoder_expert_indexes = self._unpack_router_logits(outputs[-1])
+            decoder_z_loss = router_z_loss_func(decoder_router_logits)
+            decoder_router_probs = nn.Softmax(dim=-1)(decoder_router_logits)
+            decoder_aux_loss = load_balancing_loss_func(decoder_router_probs, decoder_expert_indexes)
+            
+        if labels is not None:
+            # Shift so that tokens < n predict n
+            shift_logits = logits[..., :-1, :].contiguous()
+            shift_labels = labels[..., 1:].contiguous()
+            # Flatten the tokens
+            loss_fct = CrossEntropyLoss()
+            shift_logits = shift_logits.view(-1, self.config.vocab_size)
+            shift_labels = shift_labels.view(-1)
+            # Enable model parallelism
+            shift_labels = shift_labels.to(shift_logits.device)
+            loss = loss_fct(shift_logits, shift_labels)
+
+            ##########################
+            if output_router_logits:
+                z_loss = self.router_z_loss_coef * decoder_z_loss
+                aux_loss = self.router_aux_loss_coef * decoder_aux_loss
+                loss = loss + z_loss + aux_loss
+            #########################
+        if not return_dict:
+            output = (logits,) + outputs[1:]
+            return (loss,) + output if loss is not None else output
+
+        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, **kwargs
+    ):
+        if past_key_values:
+            input_ids = input_ids[:, -1:]
+
+        position_ids = kwargs.get("position_ids", None)
+        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 past_key_values:
+                position_ids = position_ids[:, -1].unsqueeze(-1)
+
+        # if `inputs_embeds` are passed, we only want to use them in the 1st generation step
+        if inputs_embeds is not None and past_key_values is None:
+            model_inputs = {"inputs_embeds": inputs_embeds}
+        else:
+            model_inputs = {"input_ids": input_ids}
+
+        model_inputs.update(
+            {
+                "position_ids": position_ids,
+                "past_key_values": past_key_values,
+                "use_cache": kwargs.get("use_cache"),
+                "attention_mask": attention_mask,
+            }
+        )
+        return model_inputs
+
+    @staticmethod
+    def _reorder_cache(past_key_values, beam_idx):
+        reordered_past = ()
+        for layer_past in past_key_values:
+            reordered_past += (
+                tuple(past_state.index_select(0, beam_idx.to(past_state.device)) for past_state in layer_past),
+            )
+        return reordered_past