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# Copyright (c) 2024, NVIDIA CORPORATION. All rights reserved.
#
# NVIDIA CORPORATION and its licensors retain all intellectual property
# and proprietary rights in and to this software, related documentation
# and any modifications thereto. Any use, reproduction, disclosure or
# distribution of this software and related documentation without an express
# license agreement from NVIDIA CORPORATION is strictly prohibited.
import math
from typing import Dict, Optional
import torch
from torch import nn
from einops import rearrange
from timm.models.vision_transformer import Block
from .enable_spectral_reparam import disable_spectral_reparam, enable_spectral_reparam
class MLPBase(nn.Module):
def __init__(
self,
requires_summary_and_spatial: bool,
handles_summary_and_spatial: bool = False
) -> None:
super().__init__()
self.requires_summary_and_spatial = requires_summary_and_spatial
self.handles_summary_and_spatial = handles_summary_and_spatial
assert not handles_summary_and_spatial or requires_summary_and_spatial, "If handles summary and spatial, must require it too!"
class MLP(MLPBase):
def __init__(self, input_size: int, hidden_size: int, output_size: int,
num_inner: int = 0, device: torch.device = None, **kwargs):
super(MLP, self).__init__(requires_summary_and_spatial=False)
self.fc1 = nn.Linear(input_size, hidden_size, device=device)
self.norm = nn.LayerNorm(hidden_size, device=device)
self.relu = nn.ReLU()
inner = []
for _ in range(num_inner):
inner.extend([
nn.Linear(hidden_size, hidden_size, device=device),
nn.LayerNorm(hidden_size, device=device),
nn.ReLU(),
])
if inner:
self.inner = nn.Sequential(*inner)
else:
self.inner = nn.Identity()
self.fc2 = nn.Linear(hidden_size, output_size, device=device)
def forward(self, x: torch.Tensor) -> torch.Tensor:
x = self.fc1(x)
x = self.norm(x)
x = self.relu(x)
x = self.inner(x)
x = self.fc2(x)
return x
class MLP2(MLPBase):
def __init__(self, input_size: int, hidden_size: int, output_size: int,
num_inner: int = 0,
pre_norm: bool = False, device: torch.device = None,
upsample_factor: int = 1,
upsample_rank: int = None,
from_config: bool = False,
**kwargs):
super().__init__(requires_summary_and_spatial=False)
self.pre_norm = nn.Sequential(
nn.LayerNorm(input_size),
nn.GELU(),
) if pre_norm else nn.Identity()
self.upsample_factor = upsample_factor
sq_ups = upsample_factor ** 2
self._real_output_dim = output_size // sq_ups
# hidden_size *= upsample_factor
# output_size *= (upsample_factor ** 2)
self.fc1 = nn.Linear(input_size, hidden_size, device=device)
blocks = []
for _ in range(num_inner):
blocks.append(nn.Sequential(
nn.LayerNorm(hidden_size, device=device),
nn.GELU(),
nn.Linear(hidden_size, hidden_size, device=device),
))
self.blocks = nn.ModuleList(blocks)
self.final = nn.Sequential(
nn.LayerNorm(hidden_size, device=device),
nn.GELU(),
nn.Linear(hidden_size, output_size, device=device),
)
def forward(self, x: torch.Tensor, images: Optional[torch.Tensor] = None, patch_size: Optional[int] = None) -> torch.Tensor:
x = self.pre_norm(x)
x = self.fc1(x)
for block in self.blocks:
x = x + block(x)
x = self.final(x)
if self.upsample_factor > 1:
if images is None:
raise ValueError(f'`images` cannot be `None` when the head\'s `upsample_factor > 1`!')
if patch_size is None:
raise ValueError(f'`patch_size` cannot be `None` when the head\'s `upsample_factor > 1`!')
h, w = tuple(d // patch_size for d in images.shape[-2:])
x = rearrange(x, 'b (h w) (u1 u2 c) -> b (h u1 w u2) c',
h=h, w=w, u1=self.upsample_factor, u2=self.upsample_factor,
c=self._real_output_dim)
return x
class AttnFDHead(MLPBase):
def __init__(
self,
input_size: int,
hidden_size: int,
output_size: int,
num_inner: int = 0,
pre_norm: bool = False,
device: torch.device = None,
upsample_factor: int = 1,
upsample_rank: int = 0,
**kwargs # Ignore kwargs that might be to other "mlp" verions, e.g. teacher_summary_idxs
) -> None:
super().__init__(requires_summary_and_spatial=False)
from timm.models.vision_transformer import Block
self.blocks = nn.Sequential(*[
Block(input_size, num_heads=16, init_values=1e-5)
for _ in range(2)
])
self.mlp = MLP2(input_size, hidden_size, output_size,
num_inner=0, pre_norm=pre_norm, device=device,
upsample_factor=upsample_factor, upsample_rank=upsample_rank, **kwargs)
def forward(self, x: torch.Tensor, **kwargs) -> torch.Tensor:
x = self.blocks(x)
x = self.mlp(x)
return x
MLP_SUMMARY_FACTORY = {
'v1': MLP,
'v2': MLP2,
}
MLP_FD_FACTORY = {
'v1': MLP,
'v2': MLP2,
'attn': AttnFDHead,
}
def strip_prefix(state: Dict[str, torch.Tensor], prefix: str):
state = {
k[len(prefix):]: v
for k, v in state.items()
if k.startswith(prefix)
}
return state
def get_mlp_info_from_state(version: str, state: Dict[str, torch.Tensor], prefix: str = '', spectral_weights: bool = False):
state = strip_prefix(state, prefix)
weight_suffix = 'weight' if not spectral_weights else 'parametrizations.weight.original'
if version == 'v1':
hidden_dim, input_dim = state[f'fc1.{weight_suffix}'].shape
output_dim = state[f'fc2.{weight_suffix}'].shape[0]
for num_inner in range(1000):
k = f'inner.{num_inner}.0.weight'
if k not in state:
break
elif version == 'v2':
hidden_dim, input_dim = state[f'fc1.{weight_suffix}'].shape
output_dim = state[f'final.2.{weight_suffix}'].shape[0]
for num_inner in range(1000):
k = f'blocks.{num_inner}.0.weight'
if k not in state:
break
elif version == 'attn':
hidden_dim, input_dim = state[f'mlp.fc1.{weight_suffix}'].shape
output_dim = state[f'mlp.final.2.{weight_suffix}'].shape[0]
num_inner = 0
else:
raise ValueError(f'Unsupported MLP version: {version}')
return input_dim, hidden_dim, output_dim, num_inner
def create_mlp_from_config(version: str, input_dim: int, hidden_dim: int, output_dim: int, num_inner: int, is_summary: bool = True, **kwargs):
factory = MLP_SUMMARY_FACTORY if is_summary else MLP_FD_FACTORY
ret: nn.Module = factory[version](input_dim, hidden_dim, output_dim, num_inner, from_config=True, **kwargs)
return ret
def create_mlp_from_state(version: str, state: Dict[str, torch.Tensor], prefix: str = '', spectral_weights: bool = False, is_summary: bool = True, **kwargs):
state = strip_prefix(state, prefix)
input_dim, hidden_dim, output_dim, num_inner = get_mlp_info_from_state(version, state, spectral_weights=spectral_weights)
ret: nn.Module = create_mlp_from_config(version, input_dim, hidden_dim, output_dim, num_inner, is_summary=is_summary, **kwargs)
if spectral_weights:
enable_spectral_reparam(ret, init_norm_to_current=False, state_dict_guidance=state)
ret.load_state_dict(state)
if spectral_weights:
disable_spectral_reparam(ret)
return ret
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