Convert AutoAWQ checkpoints to compressed-tensors

src/llmcompressor/modifiers/awq/convert_autoawq.py

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+"""
+Convert AutoAWQ models to llmcompressor-compatible models.
+
+This module offers the functionality to convert models quantized with AutoAWQ into
+compressed models in llmcompressor's format, which can then be served with vLLM.
+This module can be used as a CLI tool or as a Python API.
+
+## CLI Usage
+
+```sh
+python -m llmcompressor.modifiers.awq.convert_autoawq \
+  --model-name-or-path /path/to/model \
+  --output-dir /path/to/compressed/model \
+  --quantization-format naive-quantized
+```
+
+For more information, run `python -m llmcompressor.modifiers.awq.convert_autoawq --help`
+or refer to the `ConversionArgs` dataclass below.
+
+## Python API Usage
+
+```python
+from llmcompressor.modifiers.awq.convert_autoawq import load_and_convert_from_autoawq
+
+awq_model_path = "/path/to/model"  # can also be model_id on huggingface hub
+model = load_and_convert_from_autoawq(awq_model_path)
+model.generate(...)  # the converted model is now ready to be used.
+```
+"""
+
+import glob
+import os
+import re
+from dataclasses import dataclass, field
+from pathlib import Path
+from tempfile import TemporaryDirectory
+from typing import Any, Literal, cast
+
+import torch
+import transformers
+from auto_round.export.export_to_awq.utils import (
+    reverse_awq_order,
+    unpack_awq,
+)
+from compressed_tensors import ModelCompressor
+from compressed_tensors.quantization import (
+    QuantizationArgs,
+    QuantizationConfig,
+    QuantizationScheme,
+    QuantizationStatus,
+    QuantizationStrategy,
+    QuantizationType,
+)
+from huggingface_hub import load_state_dict_from_file, snapshot_download
+
+
+def is_autoawq_model(model_path: Path, trust_remote_code: bool = False) -> bool:
+    config = transformers.AutoConfig.from_pretrained(
+        model_path, trust_remote_code=trust_remote_code
+    )
+    if not hasattr(config, "quantization_config"):
+        return False
+
+    quantization_config = cast(dict[str, Any], config.quantization_config)
+    return quantization_config.get("quant_method") == "awq"
+
+
+def resolve_model_path(model_name_or_path: str) -> Path:
+    if os.path.isdir(model_name_or_path):
+        return Path(model_name_or_path)
+    else:
+        # If the input is a model ID, download the model from the Hugging Face Hub and
+        # return the path to the local directory.
+        return Path(snapshot_download(model_name_or_path))
+
+
+def load_state_dict_from_model_dir(model_path: Path) -> dict[str, torch.Tensor]:
+    weight_files = glob.glob(str(model_path / "*.safetensors"))
+    if not weight_files:
+        weight_files = glob.glob(str(model_path / "*.bin"))
+
+    state_dict = {}
+    for weight_file in weight_files:
+        state_dict.update(
+            load_state_dict_from_file(
+                weight_file, map_location="cpu", weights_only=True
+            )
+        )
+    return state_dict
+
+
+def dequantize_gemm(
+    state_dict: dict[str, torch.Tensor], prefix: str, autoawq_config: dict[str, Any]
+) -> None:
+    num_bits = cast(int, autoawq_config.get("bits"))
+    group_size = cast(int, autoawq_config.get("group_size"))
+
+    qweight = state_dict.pop(f"{prefix}.qweight")
+    scales = state_dict.pop(f"{prefix}.scales")
+    qzeros = state_dict.pop(f"{prefix}.qzeros")
+
+    def dequantize_gemm_original(
+        qweight: torch.Tensor,
+        qzeros: torch.Tensor,
+        scales: torch.Tensor,
+        bits: int,
+        group_size: int,
+    ) -> tuple[torch.Tensor, torch.Tensor]:
+        """Modified from auto_round.export.export_to_awq.utils.dequantize_gemm."""
+        # Unpack the qweight and qzeros tensors
+        iweight, izeros = unpack_awq(qweight, qzeros, bits)
+        # Reverse the order of the iweight and izeros tensors
+        iweight, izeros = reverse_awq_order(iweight, izeros, bits)
+
+        # overflow checks
+        iweight = torch.bitwise_and(iweight, (2**bits) - 1)
+        izeros = torch.bitwise_and(izeros, (2**bits) - 1)
+
+        # fp16 weights
+        scales_interleaved = scales.repeat_interleave(group_size, dim=0)
+        izeros_interleaved = izeros.repeat_interleave(group_size, dim=0)
+        fweight = (iweight - izeros_interleaved) * scales_interleaved
+
+        return fweight, izeros
+
+    weight, zero_point = dequantize_gemm_original(
+        qweight, qzeros, scales, num_bits, group_size
+    )
+
+    # AutoAWQ uses [0, 2^bits - 1], e.g., [0, 15], for quantized weights, but
+    # compressed-tensors uses [-2^(bits - 1), 2^(bits - 1) - 1], e.g., [-8, 7].
+    # Therefore, we need to shift the zero point by 2^(bits - 1) to match the range
+    # of compressed-tensors and to allow correct quant/dequantization.
+    shifted_zero_point = zero_point - 2 ** (num_bits - 1)
+
+    state_dict.update(
+        {
+            f"{prefix}.weight": weight.T,
+            f"{prefix}.weight_scale": scales.T,
+            f"{prefix}.weight_zero_point": shifted_zero_point.T,
+        }
+    )
+
+
+def dequantize_autoawq_state_dict(
+    state_dict: dict[str, torch.Tensor], autoawq_config: dict[str, Any]
+) -> dict[str, torch.Tensor]:
+    version = cast(str, autoawq_config.get("version"))
+
+    # TODO: maybe add support for other versions?
+    match version:
+        case "gemm":
+            dequantize_fn = dequantize_gemm
+        case _:
+            raise ValueError(f"Unsupported version: {version}")
+
+    keys = list(state_dict.keys())
+    for key in filter(lambda k: k.endswith("qweight"), keys):
+        prefix = key.removesuffix(".qweight")
+        dequantize_fn(state_dict, prefix, autoawq_config)
+
+    return state_dict
+
+
+def convert_and_save(
+    model_name_or_path: str,
+    output_dir: str,
+    quantization_format: str,
+    overwrite: bool = False,
+    trust_remote_code: bool = False,
+) -> None:
+    """Convert an AutoAWQ model to a compressed model and save it.
+
+    Steps:
+
+    1. Load the model weights directly.
+    2. Dequantize the weights accordingly.
+    3. Load the model with the dequantized weights.
+    4. Add the quantization parameters to the model.
+    5. Re-pack the weights using `ModelCompressor` with the correct configuration.
+    6. Save the model to the output directory.
+
+    :param model_name_or_path: Model ID on huggingface hub or path to local model.
+    :param output_dir: Path to save the converted model.
+    :param quantization_format: Compression format to be saved.
+    :param overwrite: Overwrite the existing output directory if it exists.
+    :param trust_remote_code: Whether to trust remote code.
+    """
+    output_exists = os.path.exists(output_dir)
+    is_directory = os.path.isdir(output_dir) if output_exists else False
+    is_empty_dir = False
+    if output_exists and is_directory:
+        is_empty_dir = not any(os.scandir(output_dir))
+
+    if not output_exists:
+        # Safe: output_dir does not exist
+        pass
+    elif not is_directory or (not is_empty_dir and not overwrite):
+        raise FileExistsError(
+            f"{output_dir=} already exists. Set `overwrite=True` to"
+            " overwrite the existing directory."
+        )
+
+    model_path = resolve_model_path(model_name_or_path)
+    if not is_autoawq_model(model_path, trust_remote_code):
+        raise ValueError("Model is not an AutoAWQ model")
+
+    config = transformers.AutoConfig.from_pretrained(
+        model_path, trust_remote_code=trust_remote_code
+    )
+    autoawq_config = cast(dict[str, Any], config.quantization_config)
+    num_bits = cast(int, autoawq_config.get("bits"))
+    is_symmetric = not autoawq_config.get("zero_point")
+    group_size = cast(int, autoawq_config.get("group_size"))
+
+    # Convert AutoAWQ's substring-based ignore list to llm-compressor's regex format
+    # Usage in AutoAWQ:
+    # ```python
+    # if any(key in name for key in modules_to_not_convert): ...
+    # ```
+    # See https://github.com/casper-hansen/AutoAWQ/blob/88e4c76b20755db275574e6a03c83c84ba3bece5/awq/utils/module.py#L62
+    modules_to_not_convert = autoawq_config.get("modules_to_not_convert", None)
+    ignore = []
+    if modules_to_not_convert is not None:
+        # Convert each substring pattern to a regex pattern that matches it anywhere
+        for module in modules_to_not_convert:
+            ignore.append(f"re:.*{re.escape(module)}.*")
+
+    ignore.append("lm_head")  # AutoAWQ ignores lm_head by default
+
+    # 1. Load the model weights directly.
+    state_dict = load_state_dict_from_model_dir(model_path)
+
+    # 2. Dequantize the weights accordingly.
+    state_dict = dequantize_autoawq_state_dict(state_dict, autoawq_config)
+
+    # 3. Load the model with the dequantized weights.
+    del config.quantization_config  # remove to avoid loading with AutoAWQ.
+    with transformers.modeling_utils.no_init_weights():
+        model = transformers.AutoModelForCausalLM.from_config(
+            config, torch_dtype=torch.float16, trust_remote_code=trust_remote_code
+        )
+
+    model.load_state_dict(state_dict, strict=False)
+
+    # 4. Add the quantization parameters to the model.
+    quantization_scheme = QuantizationScheme(
+        targets=["Linear"],
+        weights=QuantizationArgs(
+            num_bits=num_bits,
+            type=QuantizationType.INT,
+            symmetric=is_symmetric,
+            group_size=group_size,
+            strategy=QuantizationStrategy.GROUP,
+        ),
+    )
+
+    for key in filter(lambda k: k.endswith("weight_zero_point"), state_dict.keys()):
+        module_name = key.removesuffix(".weight_zero_point")
+        setattr(
+            model.get_submodule(module_name), "quantization_scheme", quantization_scheme
+        )
+
+    quant_config = QuantizationConfig(
+        config_groups={"group_0": quantization_scheme},
+        quant_method="compressed-tensors",
+        quantization_status=QuantizationStatus.COMPRESSED,
+        format=quantization_format,
+        ignore=ignore,
+    )
+
+    # 5. Re-pack the weights using `ModelCompressor`.
+    compressor = ModelCompressor(quantization_config=quant_config)
+    compressed_state_dict = compressor.compress(model, state_dict, show_progress=True)
+
+    # 6. Save the model.
+    tokenizer = transformers.AutoTokenizer.from_pretrained(
+        model_name_or_path, trust_remote_code=trust_remote_code
+    )
+    model.save_pretrained(output_dir, state_dict=compressed_state_dict)
+    tokenizer.save_pretrained(output_dir)
+    compressor.update_config(output_dir)
+
+
+def load_and_convert_from_autoawq(
+    model_name_or_path: str,
+    quantization_format: str = "naive-quantized",
+    trust_remote_code: bool = False,
+) -> transformers.modeling_utils.PreTrainedModel:
+    """
+    Load an AutoAWQ checkpoint and convert it to a compressed model.
+
+    :param model_name_or_path: Model ID on huggingface hub or path to local model.
+    :param quantization_format: Compression format to be saved.
+    :param trust_remote_code: Whether to trust remote code.
+    :return: A compressed model.
+    """
+    with TemporaryDirectory() as temp_dir:
+        convert_and_save(
+            model_name_or_path,
+            temp_dir,
+            quantization_format,
+            trust_remote_code=trust_remote_code,
+        )
+        return transformers.AutoModelForCausalLM.from_pretrained(
+            temp_dir, torch_dtype=torch.float16, trust_remote_code=trust_remote_code
+        )
+
+
+@dataclass
+class ConversionArgs:
+    model_name_or_path: str = field(
+        metadata={"help": "Model ID on huggingface hub or path to local model."},
+    )
+    output_dir: str = field(
+        metadata={"help": "Path to save the converted model."},
+    )
+    quantization_format: Literal["naive-quantized", "pack-quantized"] = field(
+        default="naive-quantized",
+        metadata={"help": "Compression format to be saved."},
+    )  # TODO: switch default to packed-quantized once supported by llm-compressor.
+    overwrite: bool = field(
+        default=False,
+        metadata={"help": "Overwrite the existing output directory if it exists."},
+    )
+    trust_remote_code: bool = field(
+        default=False,
+        metadata={"help": "Whether to trust remote code."},
+    )
+
+
+__all__ = ["convert_and_save", "load_and_convert_from_autoawq", "ConversionArgs"]
+
+
+if __name__ == "__main__":
+    parser = transformers.HfArgumentParser(ConversionArgs)
+    args = parser.parse_args_into_dataclasses()[0]
+    convert_and_save(
+        args.model_name_or_path,
+        args.output_dir,
+        args.quantization_format,
+        args.overwrite,
+        args.trust_remote_code,
+    )