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import torch
import random
import numpy as np
from torch import nn
import torch.nn.functional as F
def seed_everything(seed=42):
random.seed(seed)
np.random.seed(seed)
torch.manual_seed(seed)
torch.cuda.manual_seed_all(seed)
torch.backends.cudnn.deterministic = True
torch.backends.cudnn.benchmark = False
def compute_kl_divergence(model, target_model, inputs):
with torch.no_grad():
ref_outputs = target_model(**inputs)
ref_probs = F.log_softmax(ref_outputs.logits, dim=-1)
ref_probs = ref_probs.view(-1, ref_outputs.logits.shape[-1])
outputs = model(**inputs)
current_probs = F.log_softmax(outputs.logits, dim=-1)
current_probs = current_probs.view(-1, outputs.logits.shape[-1])
# minimum KL divergence
return nn.functional.kl_div(
current_probs, ref_probs, reduction="batchmean", log_target=True
), outputs
def compute_batch_nll(model, inputs):
# get the sum loss for each sequence in a batch
# NOTE: not same as model(**inputs).loss but has sum loss for each seq in a batch
outputs = model(**inputs)
logits = outputs.logits
labels = inputs["labels"]
shifted_labels = labels[..., 1:].contiguous()
logits = logits[..., :-1, :].contiguous()
loss_function = nn.CrossEntropyLoss(ignore_index=-100, reduction="none")
loss = loss_function(logits.transpose(-1, -2), shifted_labels).sum(dim=-1)
return loss, outputs
def compute_dpo_loss(model, ref_model, win_inputs=None, lose_inputs=None, beta=1.0):
if win_inputs is None and lose_inputs is None:
raise ValueError("Both win_inputs and lose_inputs can't be None")
win_log_ratio, lose_log_ratio = 0.0, 0.0
win_outputs, lose_outputs = None, None
if win_inputs is not None:
win_loss, win_outputs = compute_batch_nll(model, win_inputs)
with torch.no_grad():
win_ref_loss, _ = compute_batch_nll(ref_model, win_inputs)
win_log_ratio = -(win_loss - win_ref_loss)
if lose_inputs is not None:
lose_loss, lose_outputs = compute_batch_nll(model, lose_inputs)
with torch.no_grad():
lose_ref_loss, _ = compute_batch_nll(ref_model, lose_inputs)
lose_log_ratio = -(lose_loss - lose_ref_loss)
loss = -2 / beta * F.logsigmoid(beta * (win_log_ratio - lose_log_ratio)).mean()
return loss, (win_outputs, lose_outputs)
def compute_undial_loss(model, ref_model, inputs, beta):
# Forward pass on the student (trainable) model
outputs = model(**inputs)
logits = outputs.logits
labels = inputs["labels"]
shift_labels = labels[..., 1:].contiguous()
shift_logits = logits[..., :-1, :].contiguous()
# Forward pass on the teacher model (no grad)
with torch.no_grad():
teacher_logits = ref_model(**inputs).logits
shift_teacher_logits = teacher_logits[..., :-1, :].contiguous()
# Build the mask that identifies the tokens need to be unlearned
mask = torch.zeros_like(shift_teacher_logits)
batch_idx = torch.arange(mask.shape[0]).view(-1, 1, 1)
seq_idx = torch.arange(mask.shape[1]).view(1, -1, 1)
mask[batch_idx, seq_idx, shift_labels.unsqueeze(-1)] = 1.0
# Adjust teacher logits: subtract di_strength on the correct token
pre_softmax = shift_teacher_logits - mask * beta
soft_label = F.softmax(pre_softmax, dim=-1)
loss_fct = nn.CrossEntropyLoss(reduction="none")
loss = loss_fct(
shift_logits.view(-1, shift_logits.size(-1)),
soft_label.view(-1, soft_label.size(-1)),
)
return loss.mean(), outputs
def compute_wga_loss(model, inputs, beta):
outputs = model(**inputs)
labels = inputs["labels"]
labels = labels.to(outputs.logits.device)
shift_logits = outputs.logits[..., :-1, :].contiguous()
shift_labels = labels[..., 1:].contiguous()
lm_loss = nn.CrossEntropyLoss(ignore_index=-100, reduction="none")(
shift_logits.view(-1, shift_logits.size(-1)), shift_labels.view(-1)
)
weight_ce = ((-lm_loss).exp().detach()) ** beta
forget_loss = -(weight_ce * lm_loss)[shift_labels.view(-1) != -100].mean()
return forget_loss, outputs
def compute_satimp_loss(model, inputs, beta1, beta2):
outputs = model(**inputs)
labels = inputs["labels"]
labels = labels.to(outputs.logits.device)
shift_logits = outputs.logits[..., :-1, :].contiguous()
shift_labels = labels[..., 1:].contiguous()
lm_loss = nn.CrossEntropyLoss(ignore_index=-100, reduction="none")(
shift_logits.view(-1, shift_logits.size(-1)), shift_labels.view(-1)
)
weight_sat = ((-lm_loss).exp().detach()) ** beta1
weight_imp = (1 - (-lm_loss).exp().detach()) ** beta2
forget_loss = -((weight_sat * weight_imp) * lm_loss)[
shift_labels.view(-1) != -100
].mean()
return forget_loss, outputs