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# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# This source code is licensed under the Apache License, Version 2.0
# found in the LICENSE file in the root directory of this source tree.
import os
from typing import Callable, Optional
import warnings
from torch import Tensor, nn
import torch.nn.functional as F
class SwiGLUFFN(nn.Module):
def __init__(
self,
in_features: int,
hidden_features: Optional[int] = None,
out_features: Optional[int] = None,
act_layer: Callable[..., nn.Module] = None,
drop: float = 0.0,
bias: bool = True,
) -> None:
super().__init__()
out_features = out_features or in_features
hidden_features = hidden_features or in_features
self.w12 = nn.Linear(in_features, 2 * hidden_features, bias=bias)
self.w3 = nn.Linear(hidden_features, out_features, bias=bias)
def forward(self, x: Tensor) -> Tensor:
x12 = self.w12(x)
x1, x2 = x12.chunk(2, dim=-1)
hidden = F.silu(x1) * x2
return self.w3(hidden)
XFORMERS_ENABLED = os.environ.get("XFORMERS_DISABLED") is None
try:
if XFORMERS_ENABLED:
from xformers.ops import SwiGLU
XFORMERS_AVAILABLE = True
warnings.warn("xFormers is available (SwiGLU)")
else:
warnings.warn("xFormers is disabled (SwiGLU)")
raise ImportError
except ImportError:
SwiGLU = SwiGLUFFN
XFORMERS_AVAILABLE = False
warnings.warn("xFormers is not available (SwiGLU)")
class SwiGLUFFNFused(SwiGLU):
def __init__(
self,
in_features: int,
hidden_features: Optional[int] = None,
out_features: Optional[int] = None,
act_layer: Callable[..., nn.Module] = None,
drop: float = 0.0,
bias: bool = True,
) -> None:
out_features = out_features or in_features
hidden_features = hidden_features or in_features
hidden_features = (int(hidden_features * 2 / 3) + 7) // 8 * 8
super().__init__(
in_features=in_features,
hidden_features=hidden_features,
out_features=out_features,
bias=bias,
)