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# coding=utf-8
# Copyright 2023 The vLLM team.
# Copyright (c) Google Inc.
#
# 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.
"""Inference-only Gemma model compatible with HuggingFace weights."""
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from functools import lru_cache
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from typing import Iterable, List, Optional, Tuple
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import torch
from torch import nn
from transformers import GemmaConfig

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from vllm.attention import Attention, AttentionMetadata
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from vllm.config import LoRAConfig
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from vllm.distributed import get_tensor_model_parallel_world_size
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from vllm.logger import init_logger
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from vllm.model_executor.layers.activation import GeluAndMul
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from vllm.model_executor.layers.layernorm import RMSNorm
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from vllm.model_executor.layers.linear import (MergedColumnParallelLinear,
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                                               QKVParallelLinear,
                                               RowParallelLinear)
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from vllm.model_executor.layers.logits_processor import LogitsProcessor
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from vllm.model_executor.layers.quantization.base_config import (
    QuantizationConfig)
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from vllm.model_executor.layers.rotary_embedding import get_rope
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from vllm.model_executor.layers.sampler import Sampler
from vllm.model_executor.layers.vocab_parallel_embedding import (
    VocabParallelEmbedding)
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from vllm.model_executor.model_loader.weight_utils import default_weight_loader
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from vllm.model_executor.sampling_metadata import SamplingMetadata
from vllm.sequence import SamplerOutput

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logger = init_logger(__name__)


@lru_cache(maxsize=None)
def _get_gemma_act_fn(
    hidden_act: Optional[str],
    hidden_activation: Optional[str],
) -> nn.Module:
    if hidden_activation is None:
        if hidden_act is not None:
            logger.warning(
                "Gemma's activation function was incorrectly set to exact GeLU "
                "in the config JSON file when it was initially released. "
                "Changing the activation function to approximate GeLU "
                "(`gelu_pytorch_tanh`). If you want to use the legacy "
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                "`%s`, edit the config JSON to set "
                "`hidden_activation=%s` instead of `hidden_act`. "
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                "See https://github.com/huggingface/transformers/pull/29402 "
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                "for more details.", hidden_act, hidden_act)
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        return GeluAndMul(approximate="tanh")
    elif hidden_activation == "gelu_pytorch_tanh":
        return GeluAndMul(approximate="tanh")
    elif hidden_activation == "gelu":
        return GeluAndMul(approximate="none")
    else:
        raise ValueError(f"Activation function {hidden_act} is not "
                         "supported for Gemma models.")

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class GemmaMLP(nn.Module):

    def __init__(
        self,
        hidden_size: int,
        intermediate_size: int,
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        hidden_act: Optional[str] = None,
        hidden_activation: Optional[str] = None,
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        quant_config: Optional[QuantizationConfig] = None,
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    ) -> None:
        super().__init__()
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        self.gate_up_proj = MergedColumnParallelLinear(
            hidden_size, [intermediate_size] * 2,
            bias=False,
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            quant_config=quant_config)
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        self.down_proj = RowParallelLinear(intermediate_size,
                                           hidden_size,
                                           bias=False,
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                                           quant_config=quant_config)
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        self.act_fn = _get_gemma_act_fn(hidden_act, hidden_activation)
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    def forward(self, x):
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        gate_up, _ = self.gate_up_proj(x)
        x = self.act_fn(gate_up)
        x, _ = self.down_proj(x)
        return x
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class GemmaAttention(nn.Module):

    def __init__(self,
                 hidden_size: int,
                 num_heads: int,
                 num_kv_heads: int,
                 head_dim: int,
                 max_position_embeddings: int = 8192,
                 rope_theta: float = 10000,
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                 quant_config: Optional[QuantizationConfig] = None) -> None:
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        super().__init__()
        self.hidden_size = hidden_size
        tp_size = get_tensor_model_parallel_world_size()
        self.total_num_heads = num_heads
        assert self.total_num_heads % tp_size == 0
        self.num_heads = self.total_num_heads // tp_size
        self.total_num_kv_heads = num_kv_heads
        if self.total_num_kv_heads >= tp_size:
            # Number of KV heads is greater than TP size, so we partition
            # the KV heads across multiple tensor parallel GPUs.
            assert self.total_num_kv_heads % tp_size == 0
        else:
            # Number of KV heads is less than TP size, so we replicate
            # the KV heads across multiple tensor parallel GPUs.
            assert tp_size % self.total_num_kv_heads == 0
        self.num_kv_heads = max(1, self.total_num_kv_heads // tp_size)
        self.head_dim = head_dim
        self.q_size = self.num_heads * self.head_dim
        self.kv_size = self.num_kv_heads * self.head_dim
        self.scaling = self.head_dim**-0.5
        self.rope_theta = rope_theta

        self.qkv_proj = QKVParallelLinear(
            hidden_size,
            self.head_dim,
            self.total_num_heads,
            self.total_num_kv_heads,
            bias=False,
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            quant_config=quant_config,
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        )
        self.o_proj = RowParallelLinear(
            self.total_num_heads * self.head_dim,
            hidden_size,
            bias=False,
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            quant_config=quant_config,
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        )

        self.rotary_emb = get_rope(
            self.head_dim,
            rotary_dim=self.head_dim,
            max_position=max_position_embeddings,
            base=self.rope_theta,
            is_neox_style=True,
        )
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        self.attn = Attention(self.num_heads,
                              self.head_dim,
                              self.scaling,
                              num_kv_heads=self.num_kv_heads)
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    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
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        kv_cache: torch.Tensor,
        attn_metadata: AttentionMetadata,
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    ) -> torch.Tensor:
        qkv, _ = self.qkv_proj(hidden_states)
        q, k, v = qkv.split([self.q_size, self.kv_size, self.kv_size], dim=-1)
        q, k = self.rotary_emb(positions, q, k)
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        attn_output = self.attn(q, k, v, kv_cache, attn_metadata)
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        output, _ = self.o_proj(attn_output)
        return output


class GemmaDecoderLayer(nn.Module):

    def __init__(
        self,
        config: GemmaConfig,
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        quant_config: Optional[QuantizationConfig] = None,
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    ) -> None:
        super().__init__()
        self.hidden_size = config.hidden_size
        self.self_attn = GemmaAttention(
            hidden_size=self.hidden_size,
            num_heads=config.num_attention_heads,
            num_kv_heads=config.num_key_value_heads,
            head_dim=config.head_dim,
            max_position_embeddings=config.max_position_embeddings,
            rope_theta=config.rope_theta,
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            quant_config=quant_config,
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        )
        self.mlp = GemmaMLP(
            hidden_size=self.hidden_size,
            intermediate_size=config.intermediate_size,
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            hidden_act=config.hidden_act,
            hidden_activation=getattr(config, "hidden_activation", None),
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            quant_config=quant_config,
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        )
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        self.input_layernorm = RMSNorm(config.hidden_size,
                                       eps=config.rms_norm_eps)
        self.post_attention_layernorm = RMSNorm(config.hidden_size,
                                                eps=config.rms_norm_eps)
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    def forward(
        self,
        positions: torch.Tensor,
        hidden_states: torch.Tensor,
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        kv_cache: torch.Tensor,
        attn_metadata: AttentionMetadata,
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        residual: Optional[torch.Tensor],
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    ) -> Tuple[torch.Tensor, torch.Tensor]:
        # Self Attention
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        if residual is None:
            residual = hidden_states
            hidden_states = self.input_layernorm(hidden_states)
        else:
            hidden_states, residual = self.input_layernorm(
                hidden_states, residual)
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        hidden_states = self.self_attn(
            positions=positions,
            hidden_states=hidden_states,
            kv_cache=kv_cache,
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            attn_metadata=attn_metadata,
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        )

        # Fully Connected
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        hidden_states, residual = self.post_attention_layernorm(
            hidden_states, residual)
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        hidden_states = self.mlp(hidden_states)
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        return hidden_states, residual
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class GemmaModel(nn.Module):

    def __init__(
        self,
        config: GemmaConfig,
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        quant_config: Optional[QuantizationConfig] = None,
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    ) -> None:
        super().__init__()
        self.config = config

        self.embed_tokens = VocabParallelEmbedding(
            config.vocab_size,
            config.hidden_size,
        )
        self.layers = nn.ModuleList([
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            GemmaDecoderLayer(config, quant_config)
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            for _ in range(config.num_hidden_layers)
        ])
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        self.norm = RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
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        # Normalize the embedding by sqrt(hidden_size)
        # The normalizer's data type should be downcasted to the model's
        # data type such as bfloat16, not float32.
        # See https://github.com/huggingface/transformers/pull/29402
        normalizer = self.config.hidden_size**0.5
        self.register_buffer("normalizer", torch.tensor(normalizer))

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    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
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        kv_caches: List[torch.Tensor],
        attn_metadata: AttentionMetadata,
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    ) -> torch.Tensor:
        hidden_states = self.embed_tokens(input_ids)
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        hidden_states *= self.normalizer
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        residual = None
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        for i in range(len(self.layers)):
            layer = self.layers[i]
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            hidden_states, residual = layer(
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                positions,
                hidden_states,
                kv_caches[i],
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                attn_metadata,
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                residual,
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            )
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        hidden_states, _ = self.norm(hidden_states, residual)
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        return hidden_states


class GemmaForCausalLM(nn.Module):
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    packed_modules_mapping = {
        "qkv_proj": [
            "q_proj",
            "k_proj",
            "v_proj",
        ],
        "gate_up_proj": [
            "gate_proj",
            "up_proj",
        ],
    }

    # LoRA specific attributes
    supported_lora_modules = [
        "qkv_proj",
        "o_proj",
        "gate_up_proj",
        "down_proj",
    ]
    # Gemma does not apply LoRA to the embedding layer.
    embedding_modules = {}
    embedding_padding_modules = []
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    def __init__(
        self,
        config: GemmaConfig,
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        quant_config: Optional[QuantizationConfig] = None,
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        lora_config: Optional[LoRAConfig] = None,
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    ) -> None:
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        del lora_config  # Unused.
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        super().__init__()
        self.config = config
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        self.quant_config = quant_config
        self.model = GemmaModel(config, quant_config)
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        self.logits_processor = LogitsProcessor(config.vocab_size)
        self.sampler = Sampler()
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    @torch.no_grad()
    def forward(
        self,
        input_ids: torch.Tensor,
        positions: torch.Tensor,
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        kv_caches: List[torch.Tensor],
        attn_metadata: AttentionMetadata,
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    ) -> torch.Tensor:
        hidden_states = self.model(input_ids, positions, kv_caches,
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                                   attn_metadata)
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        return hidden_states

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    def compute_logits(self, hidden_states: torch.Tensor,
                       sampling_metadata: SamplingMetadata) -> torch.Tensor:
        logits = self.logits_processor(self.model.embed_tokens.weight,
                                       hidden_states, sampling_metadata)
        return logits

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    def sample(
        self,
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        logits: torch.Tensor,
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        sampling_metadata: SamplingMetadata,
    ) -> Optional[SamplerOutput]:
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        next_tokens = self.sampler(logits, sampling_metadata)
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        return next_tokens

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    def load_weights(self, weights: Iterable[Tuple[str, torch.Tensor]]):
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        stacked_params_mapping = [
            # (param_name, shard_name, shard_id)
            ("qkv_proj", "q_proj", "q"),
            ("qkv_proj", "k_proj", "k"),
            ("qkv_proj", "v_proj", "v"),
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            ("gate_up_proj", "gate_proj", 0),
            ("gate_up_proj", "up_proj", 1),
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        ]
        params_dict = dict(self.named_parameters())
        loaded_params = set()
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        for name, loaded_weight in weights:
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            for (param_name, shard_name, shard_id) in stacked_params_mapping:
                if shard_name not in name:
                    continue
                name = name.replace(shard_name, param_name)
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                # Skip loading extra bias for GPTQ models.
                if name.endswith(".bias") and name not in params_dict:
                    continue
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                param = params_dict[name]
                weight_loader = param.weight_loader
                weight_loader(param, loaded_weight, shard_id)
                break
            else:
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                # lm_head is not used in vllm as it is tied with embed_token.
                # To prevent errors, skip loading lm_head.weight.
                if "lm_head.weight" in name:
                    continue
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                # Skip loading extra bias for GPTQ models.
                if name.endswith(".bias") and name not in params_dict:
                    continue
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                # GemmaRMSNorm is different from Llama's in that it multiplies
                # (1 + weight) to the output, instead of just weight.
                if "norm.weight" in name:
                    loaded_weight += 1.0
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                param = params_dict[name]
                weight_loader = getattr(param, "weight_loader",
                                        default_weight_loader)
                weight_loader(param, loaded_weight)
            loaded_params.add(name)
        unloaded_params = params_dict.keys() - loaded_params
        if unloaded_params:
            raise RuntimeError(
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                "Some weights are not initialized from checkpoints: "
                f"{unloaded_params}")