# Copyright (c) Facebook, Inc. and its affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
from typing import Optional, TypeVar, Union, overload
import torch
import torch.nn.functional as F
from torch import Tensor, device, dtype, nn
import bitsandbytes as bnb
import bitsandbytes.functional
from bitsandbytes.autograd._functions import get_inverse_transform_indices, undo_layout
from bitsandbytes.optim import GlobalOptimManager
from bitsandbytes.utils import OutlierTracer, find_outlier_dims
T = TypeVar("T", bound="torch.nn.Module")
class StableEmbedding(torch.nn.Embedding):
def __init__(
self,
num_embeddings: int,
embedding_dim: int,
padding_idx: Optional[int] = None,
max_norm: Optional[float] = None,
norm_type: float = 2.0,
scale_grad_by_freq: bool = False,
sparse: bool = False,
_weight: Optional[Tensor] = None,
device=None,
dtype=None,
) -> None:
super().__init__(
num_embeddings,
embedding_dim,
padding_idx,
max_norm,
norm_type,
scale_grad_by_freq,
sparse,
_weight,
device,
dtype,
)
self.norm = torch.nn.LayerNorm(embedding_dim, device=device)
GlobalOptimManager.get_instance().register_module_override(
self, "weight", {"optim_bits": 32}
)
def reset_parameters(self) -> None:
torch.nn.init.xavier_uniform_(self.weight)
self._fill_padding_idx_with_zero()
""" !!! This is a redefinition of _fill_padding_idx_with_zero in torch.nn.Embedding
to make the Layer compatible with Pytorch < 1.9.
This means that if this changes in future PyTorch releases this need to change too
which is cumbersome. However, with this we can ensure compatibility with previous
PyTorch releases.
"""
def _fill_padding_idx_with_zero(self) -> None:
if self.padding_idx is not None:
with torch.no_grad():
self.weight[self.padding_idx].fill_(0)
def forward(self, input: Tensor) -> Tensor:
emb = F.embedding(
input,
self.weight,
self.padding_idx,
self.max_norm,
self.norm_type,
self.scale_grad_by_freq,
self.sparse,
)
# always apply layer norm in full precision
emb = emb.to(torch.get_default_dtype())
return self.norm(emb).to(self.weight.dtype)
class Embedding(torch.nn.Embedding):
def __init__(
self,
num_embeddings: int,
embedding_dim: int,
padding_idx: Optional[int] = None,
max_norm: Optional[float] = None,
norm_type: float = 2.0,
scale_grad_by_freq: bool = False,
sparse: bool = False,
_weight: Optional[Tensor] = None,
) -> None:
super().__init__(
num_embeddings,
embedding_dim,
padding_idx,
max_norm,
norm_type,
scale_grad_by_freq,
sparse,
_weight,
)
GlobalOptimManager.get_instance().register_module_override(
self, "weight", {"optim_bits": 32}
)
def reset_parameters(self) -> None:
torch.nn.init.xavier_uniform_(self.weight)
self._fill_padding_idx_with_zero()
""" !!! This is a redefinition of _fill_padding_idx_with_zero in torch.nn.Embedding
to make the Layer compatible with Pytorch < 1.9.
This means that if this changes in future PyTorch releases this need to change too
which is cumbersome. However, with this we can ensure compatibility with previous
PyTorch releases.
"""
def _fill_padding_idx_with_zero(self) -> None:
if self.padding_idx is not None:
with torch.no_grad():
self.weight[self.padding_idx].fill_(0)
def forward(self, input: Tensor) -> Tensor:
emb = F.embedding(
input,
self.weight,
self.padding_idx,
self.max_norm,
self.norm_type,
self.scale_grad_by_freq,
self.sparse,
)
return emb
class OutlierAwareLinear(nn.Linear):
def __init__(self, input_features, output_features, bias=True):
super().__init__(input_features, output_features, bias)
self.outlier_dim = None
self.is_quantized = False
def forward_with_outliers(self, x, outlier_idx):
raise NotImplementedError('Please override the `forward_with_outliers(self, x, outlier_idx)` function')
def quantize_weight(self, w, outlier_idx):
raise NotImplementedError('Please override the `quantize_weights(self, w, outlier_idx)` function')
def forward(self, x):
if self.outlier_dim is None:
tracer = OutlierTracer.get_instance()
if not tracer.is_initialized():
print('Please use OutlierTracer.initialize(model) before using the OutlierAwareLinear layer')
outlier_idx = tracer.get_outliers(self.weight)
#print(outlier_idx, tracer.get_hvalue(self.weight))
self.outlier_dim = outlier_idx
if not self.is_quantized:
w = self.quantize_weight(self.weight, self.outlier_dim)
self.weight.data.copy_(w)
self.is_quantized = True
return self.forward_with_outliers(x, self.outlier_dim)
class Int8Params(torch.nn.Parameter):
def __new__(
cls,
data=None,
requires_grad=True,
has_fp16_weights=False,
CB=None,
SCB=None,
):
cls.has_fp16_weights = has_fp16_weights
cls.CB = None
cls.SCB = None
if data is None:
data = torch.empty(0)
return torch.Tensor._make_subclass(cls, data, requires_grad)
def cuda(self, device):
if self.has_fp16_weights:
return super().cuda(device)
else:
# we store the 8-bit rows-major weight
# we convert this weight to the turning/ampere weight during the first inference pass
B = self.data.contiguous().half().cuda(device)
CB, CBt, SCB, SCBt, coo_tensorB = bnb.functional.double_quant(B)
del CBt
del SCBt
self.data = CB
setattr(self, "CB", CB)
setattr(self, "SCB", SCB)
return self
@overload
def to(
self: T,
device: Optional[Union[int, device]] = ...,
dtype: Optional[Union[dtype, str]] = ...,
non_blocking: bool = ...,
) -> T:
...
@overload
def to(self: T, dtype: Union[dtype, str], non_blocking: bool = ...) -> T:
...
@overload
def to(self: T, tensor: Tensor, non_blocking: bool = ...) -> T:
...
def to(self, *args, **kwargs):
device, dtype, non_blocking, convert_to_format = torch._C._nn._parse_to(
*args, **kwargs
)
if (
device is not None
and device.type == "cuda"
and self.data.device.type == "cpu"
):
return self.cuda(device)
else:
new_param = Int8Params(
super().to(
device=device, dtype=dtype, non_blocking=non_blocking
),
requires_grad=self.requires_grad,
has_fp16_weights=self.has_fp16_weights,
)
new_param.CB = self.CB
new_param.SCB = self.SCB
return new_param
class Linear8bitLt(nn.Linear):
def __init__(self, input_features, output_features, bias=True, has_fp16_weights=True,
memory_efficient_backward=False, threshold=0.0, index=None):
super().__init__(input_features, output_features, bias)
assert not memory_efficient_backward, "memory_efficient_backward is no longer required and the argument is deprecated in 0.37.0 and will be removed in 0.39.0"
self.state = bnb.MatmulLtState()
self.index = index
self.state.threshold = threshold
self.state.has_fp16_weights = has_fp16_weights
self.state.memory_efficient_backward = memory_efficient_backward
if threshold > 0.0 and not has_fp16_weights:
self.state.use_pool = True
self.weight = Int8Params(self.weight.data, has_fp16_weights=has_fp16_weights, requires_grad=has_fp16_weights)
def _save_to_state_dict(self, destination, prefix, keep_vars):
if not self.state.has_fp16_weights and self.state.CB is None and self.state.CxB is not None:
# reorder weight layout back from ampere/turing to row
reorder_layout = True
weight_clone = self.weight.data.clone()
else:
reorder_layout = False
try:
if reorder_layout:
self.weight.data = undo_layout(self.state.CxB, self.state.tile_indices)
super()._save_to_state_dict(destination, prefix, keep_vars)
# we only need to save SCB as extra data, because CB for quantized weights is already stored in weight.data
weight_name = "SCB"
# case 1: .cuda was called, SCB is in self.weight
param_from_weight = getattr(self.weight, weight_name)
# case 2: self.init_8bit_state was called, SCB is in self.state
param_from_state = getattr(self.state, weight_name)
key_name = prefix + f"{weight_name}"
if param_from_weight is not None:
destination[key_name] = param_from_weight if keep_vars else param_from_weight.detach()
elif not self.state.has_fp16_weights and param_from_state is not None:
destination[key_name] = param_from_state if keep_vars else param_from_state.detach()
finally:
if reorder_layout:
self.weight.data = weight_clone
def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict,
missing_keys, unexpected_keys, error_msgs):
super()._load_from_state_dict(state_dict, prefix, local_metadata, strict, missing_keys, unexpected_keys,
error_msgs)
for key in unexpected_keys:
input_name = key[len(prefix):]
if input_name == "SCB":
if self.weight.SCB is None:
# buffers not yet initialized, can't call them directly without
raise RuntimeError("Loading a quantized checkpoint into non-quantized Linear8bitLt is "
"not supported. Please call module.cuda() before module.load_state_dict()")
input_param = state_dict[key]
self.weight.SCB.copy_(input_param)
unexpected_keys.remove(key)
def init_8bit_state(self):
self.state.CB = self.weight.CB
self.state.SCB = self.weight.SCB
self.weight.CB = None
self.weight.SCB = None
def forward(self, x: torch.Tensor):
self.state.is_training = self.training
if self.weight.CB is not None:
self.init_8bit_state()
# weights are cast automatically as Int8Params, but the bias has to be cast manually
if self.bias is not None and self.bias.dtype != x.dtype:
self.bias.data = self.bias.data.to(x.dtype)
out = bnb.matmul(x, self.weight, bias=self.bias, state=self.state)
if not self.state.has_fp16_weights:
if self.state.CB is not None and self.state.CxB is not None:
# we converted 8-bit row major to turing/ampere format in the first inference pass
# we no longer need the row-major weight
del self.state.CB
self.weight.data = self.state.CxB
return out
class SwitchBackLinearBnb(nn.Linear):
def __init__(
self,
input_features,
output_features,
bias=True,
has_fp16_weights=True,
memory_efficient_backward=False,
threshold=0.0,
index=None,
):
super().__init__(
input_features, output_features, bias
)
self.state = bnb.MatmulLtState()
self.index = index
self.state.threshold = threshold
self.state.has_fp16_weights = has_fp16_weights
self.state.memory_efficient_backward = memory_efficient_backward
if threshold > 0.0 and not has_fp16_weights:
self.state.use_pool = True
self.weight = Int8Params(
self.weight.data, has_fp16_weights=has_fp16_weights, requires_grad=has_fp16_weights
)
def init_8bit_state(self):
self.state.CB = self.weight.CB
self.state.SCB = self.weight.SCB
self.weight.CB = None
self.weight.SCB = None
def forward(self, x):
self.state.is_training = self.training
if self.weight.CB is not None:
self.init_8bit_state()
out = bnb.matmul_mixed(x.half(), self.weight.half(), bias=None, state=self.state) + self.bias