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321 lines (254 loc) · 11.5 KB
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# Copyright 2023 The HuggingFace Team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import math
import torch
from torch import nn
from ..configuration_utils import ConfigMixin, register_to_config
from .attention_processor import Attention
from .embeddings import get_timestep_embedding
from .modeling_utils import ModelMixin
class T5FilmDecoder(ModelMixin, ConfigMixin):
@register_to_config
def __init__(
self,
input_dims: int = 128,
targets_length: int = 256,
max_decoder_noise_time: float = 2000.0,
d_model: int = 768,
num_layers: int = 12,
num_heads: int = 12,
d_kv: int = 64,
d_ff: int = 2048,
dropout_rate: float = 0.1,
):
super().__init__()
self.conditioning_emb = nn.Sequential(
nn.Linear(d_model, d_model * 4, bias=False),
nn.SiLU(),
nn.Linear(d_model * 4, d_model * 4, bias=False),
nn.SiLU(),
)
self.position_encoding = nn.Embedding(targets_length, d_model)
self.position_encoding.weight.requires_grad = False
self.continuous_inputs_projection = nn.Linear(input_dims, d_model, bias=False)
self.dropout = nn.Dropout(p=dropout_rate)
self.decoders = nn.ModuleList()
for lyr_num in range(num_layers):
# FiLM conditional T5 decoder
lyr = DecoderLayer(d_model=d_model, d_kv=d_kv, num_heads=num_heads, d_ff=d_ff, dropout_rate=dropout_rate)
self.decoders.append(lyr)
self.decoder_norm = T5LayerNorm(d_model)
self.post_dropout = nn.Dropout(p=dropout_rate)
self.spec_out = nn.Linear(d_model, input_dims, bias=False)
def encoder_decoder_mask(self, query_input, key_input):
mask = torch.mul(query_input.unsqueeze(-1), key_input.unsqueeze(-2))
return mask.unsqueeze(-3)
def forward(self, encodings_and_masks, decoder_input_tokens, decoder_noise_time):
batch, _, _ = decoder_input_tokens.shape
assert decoder_noise_time.shape == (batch,)
# decoder_noise_time is in [0, 1), so rescale to expected timing range.
time_steps = get_timestep_embedding(
decoder_noise_time * self.config.max_decoder_noise_time,
embedding_dim=self.config.d_model,
max_period=self.config.max_decoder_noise_time,
).to(dtype=self.dtype)
conditioning_emb = self.conditioning_emb(time_steps).unsqueeze(1)
assert conditioning_emb.shape == (batch, 1, self.config.d_model * 4)
seq_length = decoder_input_tokens.shape[1]
# If we want to use relative positions for audio context, we can just offset
# this sequence by the length of encodings_and_masks.
decoder_positions = torch.broadcast_to(
torch.arange(seq_length, device=decoder_input_tokens.device),
(batch, seq_length),
)
position_encodings = self.position_encoding(decoder_positions)
inputs = self.continuous_inputs_projection(decoder_input_tokens)
inputs += position_encodings
y = self.dropout(inputs)
# decoder: No padding present.
decoder_mask = torch.ones(
decoder_input_tokens.shape[:2], device=decoder_input_tokens.device, dtype=inputs.dtype
)
# Translate encoding masks to encoder-decoder masks.
encodings_and_encdec_masks = [(x, self.encoder_decoder_mask(decoder_mask, y)) for x, y in encodings_and_masks]
# cross attend style: concat encodings
encoded = torch.cat([x[0] for x in encodings_and_encdec_masks], dim=1)
encoder_decoder_mask = torch.cat([x[1] for x in encodings_and_encdec_masks], dim=-1)
for lyr in self.decoders:
y = lyr(
y,
conditioning_emb=conditioning_emb,
encoder_hidden_states=encoded,
encoder_attention_mask=encoder_decoder_mask,
)[0]
y = self.decoder_norm(y)
y = self.post_dropout(y)
spec_out = self.spec_out(y)
return spec_out
class DecoderLayer(nn.Module):
def __init__(self, d_model, d_kv, num_heads, d_ff, dropout_rate, layer_norm_epsilon=1e-6):
super().__init__()
self.layer = nn.ModuleList()
# cond self attention: layer 0
self.layer.append(
T5LayerSelfAttentionCond(d_model=d_model, d_kv=d_kv, num_heads=num_heads, dropout_rate=dropout_rate)
)
# cross attention: layer 1
self.layer.append(
T5LayerCrossAttention(
d_model=d_model,
d_kv=d_kv,
num_heads=num_heads,
dropout_rate=dropout_rate,
layer_norm_epsilon=layer_norm_epsilon,
)
)
# Film Cond MLP + dropout: last layer
self.layer.append(
T5LayerFFCond(d_model=d_model, d_ff=d_ff, dropout_rate=dropout_rate, layer_norm_epsilon=layer_norm_epsilon)
)
def forward(
self,
hidden_states,
conditioning_emb=None,
attention_mask=None,
encoder_hidden_states=None,
encoder_attention_mask=None,
encoder_decoder_position_bias=None,
):
hidden_states = self.layer[0](
hidden_states,
conditioning_emb=conditioning_emb,
attention_mask=attention_mask,
)
if encoder_hidden_states is not None:
encoder_extended_attention_mask = torch.where(encoder_attention_mask > 0, 0, -1e10).to(
encoder_hidden_states.dtype
)
hidden_states = self.layer[1](
hidden_states,
key_value_states=encoder_hidden_states,
attention_mask=encoder_extended_attention_mask,
)
# Apply Film Conditional Feed Forward layer
hidden_states = self.layer[-1](hidden_states, conditioning_emb)
return (hidden_states,)
class T5LayerSelfAttentionCond(nn.Module):
def __init__(self, d_model, d_kv, num_heads, dropout_rate):
super().__init__()
self.layer_norm = T5LayerNorm(d_model)
self.FiLMLayer = T5FiLMLayer(in_features=d_model * 4, out_features=d_model)
self.attention = Attention(query_dim=d_model, heads=num_heads, dim_head=d_kv, out_bias=False, scale_qk=False)
self.dropout = nn.Dropout(dropout_rate)
def forward(
self,
hidden_states,
conditioning_emb=None,
attention_mask=None,
):
# pre_self_attention_layer_norm
normed_hidden_states = self.layer_norm(hidden_states)
if conditioning_emb is not None:
normed_hidden_states = self.FiLMLayer(normed_hidden_states, conditioning_emb)
# Self-attention block
attention_output = self.attention(normed_hidden_states)
hidden_states = hidden_states + self.dropout(attention_output)
return hidden_states
class T5LayerCrossAttention(nn.Module):
def __init__(self, d_model, d_kv, num_heads, dropout_rate, layer_norm_epsilon):
super().__init__()
self.attention = Attention(query_dim=d_model, heads=num_heads, dim_head=d_kv, out_bias=False, scale_qk=False)
self.layer_norm = T5LayerNorm(d_model, eps=layer_norm_epsilon)
self.dropout = nn.Dropout(dropout_rate)
def forward(
self,
hidden_states,
key_value_states=None,
attention_mask=None,
):
normed_hidden_states = self.layer_norm(hidden_states)
attention_output = self.attention(
normed_hidden_states,
encoder_hidden_states=key_value_states,
attention_mask=attention_mask.squeeze(1),
)
layer_output = hidden_states + self.dropout(attention_output)
return layer_output
class T5LayerFFCond(nn.Module):
def __init__(self, d_model, d_ff, dropout_rate, layer_norm_epsilon):
super().__init__()
self.DenseReluDense = T5DenseGatedActDense(d_model=d_model, d_ff=d_ff, dropout_rate=dropout_rate)
self.film = T5FiLMLayer(in_features=d_model * 4, out_features=d_model)
self.layer_norm = T5LayerNorm(d_model, eps=layer_norm_epsilon)
self.dropout = nn.Dropout(dropout_rate)
def forward(self, hidden_states, conditioning_emb=None):
forwarded_states = self.layer_norm(hidden_states)
if conditioning_emb is not None:
forwarded_states = self.film(forwarded_states, conditioning_emb)
forwarded_states = self.DenseReluDense(forwarded_states)
hidden_states = hidden_states + self.dropout(forwarded_states)
return hidden_states
class T5DenseGatedActDense(nn.Module):
def __init__(self, d_model, d_ff, dropout_rate):
super().__init__()
self.wi_0 = nn.Linear(d_model, d_ff, bias=False)
self.wi_1 = nn.Linear(d_model, d_ff, bias=False)
self.wo = nn.Linear(d_ff, d_model, bias=False)
self.dropout = nn.Dropout(dropout_rate)
self.act = NewGELUActivation()
def forward(self, hidden_states):
hidden_gelu = self.act(self.wi_0(hidden_states))
hidden_linear = self.wi_1(hidden_states)
hidden_states = hidden_gelu * hidden_linear
hidden_states = self.dropout(hidden_states)
hidden_states = self.wo(hidden_states)
return hidden_states
class T5LayerNorm(nn.Module):
def __init__(self, hidden_size, eps=1e-6):
"""
Construct a layernorm module in the T5 style. No bias and no subtraction of mean.
"""
super().__init__()
self.weight = nn.Parameter(torch.ones(hidden_size))
self.variance_epsilon = eps
def forward(self, hidden_states):
# T5 uses a layer_norm which only scales and doesn't shift, which is also known as Root Mean
# Square Layer Normalization https://arxiv.org/abs/1910.07467 thus variance is calculated
# w/o mean and there is no bias. Additionally we want to make sure that the accumulation for
# half-precision inputs is done in fp32
variance = hidden_states.to(torch.float32).pow(2).mean(-1, keepdim=True)
hidden_states = hidden_states * torch.rsqrt(variance + self.variance_epsilon)
# convert into half-precision if necessary
if self.weight.dtype in [torch.float16, torch.bfloat16]:
hidden_states = hidden_states.to(self.weight.dtype)
return self.weight * hidden_states
class NewGELUActivation(nn.Module):
"""
Implementation of the GELU activation function currently in Google BERT repo (identical to OpenAI GPT). Also see
the Gaussian Error Linear Units paper: https://arxiv.org/abs/1606.08415
"""
def forward(self, input: torch.Tensor) -> torch.Tensor:
return 0.5 * input * (1.0 + torch.tanh(math.sqrt(2.0 / math.pi) * (input + 0.044715 * torch.pow(input, 3.0))))
class T5FiLMLayer(nn.Module):
"""
FiLM Layer
"""
def __init__(self, in_features, out_features):
super().__init__()
self.scale_bias = nn.Linear(in_features, out_features * 2, bias=False)
def forward(self, x, conditioning_emb):
emb = self.scale_bias(conditioning_emb)
scale, shift = torch.chunk(emb, 2, -1)
x = x * (1 + scale) + shift
return x
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