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# 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.
import dynamicconv_cuda
import torch
import torch.nn.functional as F
from fairseq import utils
from fairseq.incremental_decoding_utils import with_incremental_state
from fairseq.modules.fairseq_dropout import FairseqDropout
from fairseq.modules.unfold import unfold1d
from torch import nn
from torch.autograd import Function
class dynamicconvFunction(Function):
@staticmethod
def forward(ctx, x, weights, padding_l):
ctx.padding_l = padding_l
outputs = dynamicconv_cuda.forward(x, weights, padding_l)
variables = [x, weights]
ctx.save_for_backward(*variables)
return outputs[0]
@staticmethod
def backward(ctx, grad_output):
outputs = dynamicconv_cuda.backward(
grad_output.contiguous(), ctx.padding_l, *ctx.saved_tensors
)
grad_input, grad_weights = outputs
return grad_input, grad_weights, None
@with_incremental_state
class DynamicconvLayer(nn.Module):
def __init__(
self,
input_size,
kernel_size=1,
padding_l=None,
weight_softmax=False,
num_heads=1,
weight_dropout=0.0,
bias=False,
renorm_padding=False,
conv_bias=False,
query_size=None,
):
super(DynamicconvLayer, self).__init__()
self.input_size = input_size
self.query_size = input_size if query_size is None else query_size
self.kernel_size = kernel_size
self.padding_l = padding_l
self.num_heads = num_heads
self.weight_softmax = weight_softmax
self.weight_dropout_module = FairseqDropout(
weight_dropout, module_name=self.__class__.__name__
)
self.renorm_padding = renorm_padding
self.bias = bias
self.weight_linear = nn.Linear(input_size, num_heads * kernel_size, bias)
if conv_bias:
self.conv_bias = nn.Parameter(torch.Tensor(input_size))
else:
self.conv_bias = None
self.reset_parameters()
def reset_parameters(self):
nn.init.xavier_uniform_(self.weight_linear.weight)
if self.conv_bias is not None:
nn.init.constant_(self.conv_bias, 0.0)
nn.init.constant_(self.weight_linaer.bias, 0.0)
def forward(self, x, incremental_state=None, query=None, unfold=None):
T, B, C = x.size()
K, H = self.kernel_size, self.num_heads
# R = C // H
# during inference time, incremental BMM is faster
if incremental_state is not None:
unfold = (
x.size(0) > 512 if unfold is None else unfold
) # use unfold mode as default for long sequence to save memory
unfold = unfold or (incremental_state is not None)
assert query is None
if query is None:
query = x
if unfold:
output = self._forward_unfolded(x, incremental_state, query)
else:
output = self._forward_expanded(x, incremental_state, query)
if self.conv_bias is not None:
output = output + self.conv_bias.view(1, 1, -1)
return output
# during training time, use CUDA kernel
else:
weight = self.weight_linear(x).view(T, B, H, K)
if self.weight_softmax:
weight = F.softmax(weight, dim=-1)
if self.weight_dropout_module.p:
weight = self.weight_dropout_module(weight)
weight = weight.permute(1, 2, 3, 0).contiguous()
self.filters = weight
x = x.permute(1, 2, 0).contiguous()
output = dynamicconvFunction.apply(x, weight, self.padding_l).permute(
2, 0, 1
)
if self.conv_bias is not None:
output = output + self.conv_bias.view(1, 1, -1)
return output
def reorder_incremental_state(self, incremental_state, new_order):
input_buffer = self._get_input_buffer(incremental_state)
if input_buffer is not None:
input_buffer = input_buffer.index_select(1, new_order)
self._set_input_buffer(incremental_state, input_buffer)
def _get_input_buffer(self, incremental_state):
return utils.get_incremental_state(self, incremental_state, "input_buffer")
def _set_input_buffer(self, incremental_state, new_buffer):
return utils.set_incremental_state(
self, incremental_state, "input_buffer", new_buffer
)
def _forward_unfolded(self, x, incremental_state, query):
"""The conventional implementation of convolutions.
Unfolding the input by having a window shifting to the right."""
T, B, C = x.size()
K, H = self.kernel_size, self.num_heads
R = C // H
assert R * H == C == self.input_size
weight = self.weight_linear(query).view(T * B * H, -1)
# renorm_padding is only implemented in _forward_expanded
assert not self.renorm_padding or incremental_state is not None
if incremental_state is not None:
input_buffer = self._get_input_buffer(incremental_state)
if input_buffer is None:
input_buffer = x.new()
x_unfold = torch.cat([input_buffer, x.unsqueeze(3)], dim=3)
if self.kernel_size > 1:
self._set_input_buffer(
incremental_state, x_unfold[:, :, :, -self.kernel_size + 1 :]
)
x_unfold = x_unfold.view(T * B * H, R, -1)
else:
padding_l = self.padding_l
if K > T and padding_l == K - 1:
weight = weight.narrow(1, K - T, T)
K, padding_l = T, T - 1
# unfold the input: T x B x C --> T' x B x C x K
x_unfold = unfold1d(x, K, padding_l, 0)
x_unfold = x_unfold.view(T * B * H, R, K)
if self.weight_softmax and not self.renorm_padding:
weight = F.softmax(weight, dim=1)
weight = weight.narrow(1, 0, K)
if incremental_state is not None:
weight = weight[:, -x_unfold.size(2) :]
K = weight.size(1)
if self.weight_softmax and self.renorm_padding:
weight = F.softmax(weight, dim=1)
weight = self.weight_dropout_module(weight, inplace=False)
output = torch.bmm(x_unfold, weight.unsqueeze(2)) # T*B*H x R x 1
output = output.view(T, B, C)
return output
def _forward_expanded(self, x, incremental_stat, query):
"""Turn the convolution filters into band matrices and do matrix multiplication.
This is faster when the sequence is short, but less memory efficient.
This is not used in the decoder during inference.
"""
T, B, C = x.size()
K, H = self.kernel_size, self.num_heads
R = C // H
assert R * H == C == self.input_size
weight = self.weight_linear(query).view(T * B * H, -1)
if not self.renorm_padding:
if self.weight_softmax:
weight = F.softmax(weight, dim=1)
weight = self.weight_dropout_module(weight, inplace=False)
weight = weight.narrow(1, 0, K).contiguous()
weight = weight.view(T, B * H, K).transpose(0, 1)
x = x.view(T, B * H, R).transpose(0, 1)
if self.weight_softmax and self.renorm_padding:
# turn the convolution filters into band matrices
weight_expanded = weight.new(B * H, T, T + K - 1).fill_(float("-inf"))
weight_expanded.as_strided(
(B * H, T, K), (T * (T + K - 1), T + K, 1)
).copy_(weight)
weight_expanded = weight_expanded.narrow(2, self.padding_l, T)
# normalize the weight over valid positions like self-attention
weight_expanded = F.softmax(weight_expanded, dim=2)
weight_expanded = self.weight_dropout_module(weight_expanded, inplace=False)
else:
P = self.padding_l
# For efficiency, we cut the kernel size and reduce the padding when the kernel is larger than the length
if K > T and P == K - 1:
weight = weight.narrow(2, K - T, T)
K, P = T, T - 1
# turn the convolution filters into band matrices
weight_expanded = weight.new_zeros(B * H, T, T + K - 1, requires_grad=False)
weight_expanded.as_strided(
(B * H, T, K), (T * (T + K - 1), T + K, 1)
).copy_(weight)
weight_expanded = weight_expanded.narrow(2, P, T) # B*H x T x T
output = torch.bmm(weight_expanded, x)
output = output.transpose(0, 1).contiguous().view(T, B, C)
return output
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