mistral.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
from typing import Any

from transformers import PretrainedConfig

from vllm.logger import init_logger

logger = init_logger(__name__)


def adapt_config_dict(config_dict: dict[str, Any],
                      **kwargs) -> PretrainedConfig:
    config_dict.update(kwargs)
    config_dict = _remap_general_mistral_args(config_dict)

    if bool(config_dict.get("quantization")):
        config_dict = _remap_mistral_quantization_args(config_dict)

    if bool(config_dict.get("moe")):
        config_dict["architectures"] = ["MixtralForCausalLM"]
    else:
        config_dict["architectures"] = ["MistralForCausalLM"]

    if bool(config_dict.get("yarn")):
        config_dict = _remap_mistral_yarn_args(config_dict)
    if bool((config_dict.get("multimodal") or {}).get("vision_encoder_args")
            or config_dict.get("vision_encoder")):
        config_dict = _remap_mistral_vision_args(config_dict)

    config = PretrainedConfig.from_dict(config_dict)

    logger.debug("Initialized config", config)

    return config


def _remap_mistral_vision_args(config: dict) -> dict:
    if config.get("multimodal"):
        vision_config = config.pop("multimodal")
    else:
        vision_config = config.pop("vision_encoder")

    quant_config = config.get("quantization_config")
    config = {
        "model_type": "pixtral",
        "architectures": ["PixtralForConditionalGeneration"],
        "text_config": PretrainedConfig.from_dict(config),
        "vision_config": PretrainedConfig.from_dict(vision_config),
    }
    if quant_config:
        config["quantization_config"] = quant_config
    return config


def _remap_mistral_yarn_args(config: dict) -> dict:
    # Direct remaps: yarn.X -> rope_scaling.Y
    # Source keys are from mistral.model.args.YarnArgs
    _map = {
        "beta": "beta_fast",
        "alpha": "beta_slow",
    }
    yarn_config = config.get("yarn") or {}
    renamed_yarn_config = {_map.get(k, k): v for k, v in yarn_config.items()}
    config["rope_scaling"] = {
        "rope_type": "yarn",
        "mscale_all_dim": 1,  # We hardcoded this to 1
        **renamed_yarn_config
    }
    return config


def _remap_general_mistral_args(config: dict) -> dict:
    # Mistral key -> HF key
    config_mapping = {
        "dim": "hidden_size",
        "norm_eps": "rms_norm_eps",
        "n_kv_heads": "num_key_value_heads",
        "n_layers": "num_hidden_layers",
        "n_heads": "num_attention_heads",
        "hidden_dim": "intermediate_size",
    }
    # HF key -> (Mistral key, default value)
    top_level_mapping_with_default = {
        "model_type": ("model_type", "transformer"),
        "hidden_act": ("activation", "silu"),
        "tie_word_embeddings": ("tied_embeddings", False),
        "max_seq_len": ("max_seq_len", 128_000),
        "max_position_embeddings": ("max_position_embeddings", 128_000),
    }

    for key, new_key in config_mapping.items():
        if key in config:
            config[new_key] = config.pop(key)

    for new_key, (key,
                  default_value) in top_level_mapping_with_default.items():
        config[new_key] = config.pop(key, default_value)

    return config


def _remap_mistral_quantization_args(config: dict) -> dict:
    quantization = config.get("quantization", {})
    if quantization.get("qformat_weight") == "fp8_e4m3":
        # This maps to the FP8 static per-tensor quantization scheme
        quantization_config = {
            "quant_method": "fp8",
            "activation_scheme": "static"
        }
    elif quantization.get("quant_method") == "compressed-tensors":
        # Pass through the quantization config to compressed-tensors
        quantization_config = quantization
    else:
        raise ValueError(
            f"Found unknown quantization='{quantization}' in config")

    config["quantization_config"] = quantization_config

    return config