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vllm-omni/vllm_omni/diffusion/models/wan2_2/norm.py
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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
"""Normalization layer used by the Wan VAE patch."""
import torch
import torch.nn as nn
import torch.nn.functional as F
from vllm_omni.diffusion.layers.custom_op import CustomOp
class RMSNormVAE(CustomOp):
"""Root Mean Square Layer Normalization for Channel-First or Last"""
def __init__(
self,
dim: int,
channel_first: bool = True,
images: bool = True,
bias: bool = False,
epsilon: float = 1e-6,
) -> None:
super().__init__()
broadcastable_dims = (1, 1, 1) if not images else (1, 1)
shape = (dim, *broadcastable_dims) if channel_first else (dim,)
self.channel_first = channel_first
self.scale = dim**0.5
self.gamma = nn.Parameter(torch.ones(shape))
self.bias = nn.Parameter(torch.zeros(shape)) if bias else None
self.epsilon = epsilon
self.gamma_rmsnorm = None
def forward_cuda(
self,
x: torch.Tensor,
) -> torch.Tensor:
return self.forward_native(x)
def forward_hip(
self,
x: torch.Tensor,
) -> torch.Tensor:
return self.forward_native(x)
def forward_npu(
self,
x: torch.Tensor,
) -> torch.Tensor:
import torch_npu
if self.gamma_rmsnorm is None:
self.gamma_rmsnorm = self.gamma.reshape(-1)
if self.channel_first:
x = x.transpose(1, -1)
out = torch_npu.npu_rms_norm(x, self.gamma_rmsnorm, epsilon=self.epsilon)[0].transpose(1, -1)
else:
out = torch_npu.npu_rms_norm(x, self.gamma_rmsnorm, epsilon=self.epsilon)[0]
if self.bias is not None:
out = out + self.bias
return out
def forward_native(
self,
x: torch.Tensor,
) -> torch.Tensor:
out = (
F.normalize(
x,
dim=(1 if self.channel_first else -1),
eps=self.epsilon,
)
* self.scale
* self.gamma
)
if self.bias is not None:
out = out + self.bias
return out