from __future__ import annotations
from typing import Iterable, TYPE_CHECKING
if TYPE_CHECKING:
from torch import Tensor
from .base import ModelBase, TextModel, gguf
@ModelBase.register("BitnetForCausalLM", "BitNetForCausalLM")
@ModelBase.example("microsoft/bitnet-b1.58-2B-4T")
class BitnetModel(TextModel):
model_arch = gguf.MODEL_ARCH.BITNET
def set_vocab(self):
self._set_vocab_sentencepiece()
def set_gguf_parameters(self):
super().set_gguf_parameters()
self.gguf_writer.add_rope_scaling_type(gguf.RopeScalingType.LINEAR)
self.gguf_writer.add_rope_scaling_factor(1.0)
def weight_quant(self, weight: Tensor) -> Tensor:
dtype = weight.dtype
weight = weight.float()
scale = weight.abs().mean().clamp(min=1e-5)
iscale = 1 / scale
# TODO: multiply by the scale directly instead of inverting it twice
# (this is also unnecessarily doubly inverted upstream)
# ref: https://huggingface.co/1bitLLM/bitnet_b1_58-3B/blob/af89e318d78a70802061246bf037199d2fb97020/utils_quant.py#L10
result = (weight * iscale).round().clamp(-1, 1) / iscale
return result.type(dtype)
def modify_tensors(self, data_torch: Tensor, name: str, bid: int | None) -> Iterable[tuple[str, Tensor]]:
new_name = self.map_tensor_name(name)
if any(self.match_model_tensor_name(new_name, key, bid) for key in [
gguf.MODEL_TENSOR.ATTN_Q,
gguf.MODEL_TENSOR.ATTN_K,
gguf.MODEL_TENSOR.ATTN_V,
gguf.MODEL_TENSOR.ATTN_OUT,
gguf.MODEL_TENSOR.FFN_UP,
gguf.MODEL_TENSOR.FFN_DOWN,
gguf.MODEL_TENSOR.FFN_GATE,
]):
# transform weight into 1/0/-1 (in fp32)
data_torch = self.weight_quant(data_torch)
yield from super().modify_tensors(data_torch, name, bid)