# Copyright (c) ByteDance, Inc. and its affiliates. # All rights reserved. # # This source code is licensed under the license found in the # LICENSE file in the root directory of this source tree. import torch import torch.nn as nn from timm.models.layers import DropPath _cur_active: torch.Tensor = None # B1ff # todo: try to use `gather` for speed? def _get_active_ex_or_ii(H, W, returning_active_ex=True): h_repeat, w_repeat = H // _cur_active.shape[-2], W // _cur_active.shape[-1] active_ex = _cur_active.repeat_interleave(h_repeat, dim=2).repeat_interleave(w_repeat, dim=3) return active_ex if returning_active_ex else active_ex.squeeze(1).nonzero(as_tuple=True) # ii: bi, hi, wi def sp_conv_forward(self, x: torch.Tensor): x = super(type(self), self).forward(x) x *= _get_active_ex_or_ii(H=x.shape[2], W=x.shape[3], returning_active_ex=True) # (BCHW) *= (B1HW), mask the output of conv return x def sp_bn_forward(self, x: torch.Tensor): ii = _get_active_ex_or_ii(H=x.shape[2], W=x.shape[3], returning_active_ex=False) bhwc = x.permute(0, 2, 3, 1) nc = bhwc[ii] # select the features on non-masked positions to form a flatten feature `nc` nc = super(type(self), self).forward(nc) # use BN1d to normalize this flatten feature `nc` bchw = torch.zeros_like(bhwc) bchw[ii] = nc bchw = bchw.permute(0, 3, 1, 2) return bchw class SparseConv2d(nn.Conv2d): forward = sp_conv_forward # hack: override the forward function; see `sp_conv_forward` above for more details class SparseMaxPooling(nn.MaxPool2d): forward = sp_conv_forward # hack: override the forward function; see `sp_conv_forward` above for more details class SparseAvgPooling(nn.AvgPool2d): forward = sp_conv_forward # hack: override the forward function; see `sp_conv_forward` above for more details class SparseBatchNorm2d(nn.BatchNorm1d): forward = sp_bn_forward # hack: override the forward function; see `sp_bn_forward` above for more details class SparseSyncBatchNorm2d(nn.SyncBatchNorm): forward = sp_bn_forward # hack: override the forward function; see `sp_bn_forward` above for more details class SparseConvNeXtLayerNorm(nn.LayerNorm): r""" LayerNorm that supports two data formats: channels_last (default) or channels_first. The ordering of the dimensions in the inputs. channels_last corresponds to inputs with shape (batch_size, height, width, channels) while channels_first corresponds to inputs with shape (batch_size, channels, height, width). """ def __init__(self, normalized_shape, eps=1e-6, data_format="channels_last", sparse=True): if data_format not in ["channels_last", "channels_first"]: raise NotImplementedError super().__init__(normalized_shape, eps, elementwise_affine=True) self.data_format = data_format self.sparse = sparse def forward(self, x): if x.ndim == 4: # BHWC or BCHW if self.data_format == "channels_last": # BHWC if self.sparse: ii = _get_active_ex_or_ii(H=x.shape[1], W=x.shape[2], returning_active_ex=False) nc = x[ii] nc = super(SparseConvNeXtLayerNorm, self).forward(nc) x = torch.zeros_like(x) x[ii] = nc return x else: return super(SparseConvNeXtLayerNorm, self).forward(x) else: # channels_first, BCHW if self.sparse: ii = _get_active_ex_or_ii(H=x.shape[2], W=x.shape[3], returning_active_ex=False) bhwc = x.permute(0, 2, 3, 1) nc = bhwc[ii] nc = super(SparseConvNeXtLayerNorm, self).forward(nc) x = torch.zeros_like(bhwc) x[ii] = nc return x.permute(0, 3, 1, 2) else: u = x.mean(1, keepdim=True) s = (x - u).pow(2).mean(1, keepdim=True) x = (x - u) / torch.sqrt(s + self.eps) x = self.weight[:, None, None] * x + self.bias[:, None, None] return x else: # BLC or BC if self.sparse: raise NotImplementedError else: return super(SparseConvNeXtLayerNorm, self).forward(x) def __repr__(self): return super(SparseConvNeXtLayerNorm, self).__repr__()[:-1] + f', ch={self.data_format.split("_")[-1]}, sp={self.sparse})' class SparseConvNeXtBlock(nn.Module): r""" ConvNeXt Block. There are two equivalent implementations: (1) DwConv -> LayerNorm (channels_first) -> 1x1 Conv -> GELU -> 1x1 Conv; all in (N, C, H, W) (2) DwConv -> Permute to (N, H, W, C); LayerNorm (channels_last) -> Linear -> GELU -> Linear; Permute back We use (2) as we find it slightly faster in PyTorch Args: dim (int): Number of input channels. drop_path (float): Stochastic depth rate. Default: 0.0 layer_scale_init_value (float): Init value for Layer Scale. Default: 1e-6. """ def __init__(self, dim, drop_path=0., layer_scale_init_value=1e-6, sparse=True, ks=7): super().__init__() self.dwconv = nn.Conv2d(dim, dim, kernel_size=ks, padding=ks//2, groups=dim) # depthwise conv self.norm = SparseConvNeXtLayerNorm(dim, eps=1e-6, sparse=sparse) self.pwconv1 = nn.Linear(dim, 4 * dim) # pointwise/1x1 convs, implemented with linear layers self.act = nn.GELU() self.pwconv2 = nn.Linear(4 * dim, dim) self.gamma = nn.Parameter(layer_scale_init_value * torch.ones((dim)), requires_grad=True) if layer_scale_init_value > 0 else None self.drop_path: nn.Module = DropPath(drop_path) if drop_path > 0. else nn.Identity() self.sparse = sparse def forward(self, x): input = x x = self.dwconv(x) x = x.permute(0, 2, 3, 1) # (N, C, H, W) -> (N, H, W, C) x = self.norm(x) x = self.pwconv1(x) x = self.act(x) # GELU(0) == (0), so there is no need to mask x (no need to `x *= _get_active_ex_or_ii`) x = self.pwconv2(x) if self.gamma is not None: x = self.gamma * x x = x.permute(0, 3, 1, 2) # (N, H, W, C) -> (N, C, H, W) if self.sparse: x *= _get_active_ex_or_ii(H=x.shape[2], W=x.shape[3], returning_active_ex=True) x = input + self.drop_path(x) return x def __repr__(self): return super(SparseConvNeXtBlock, self).__repr__()[:-1] + f', sp={self.sparse})' class SparseEncoder(nn.Module): def __init__(self, cnn, input_size, sbn=False, verbose=False): super(SparseEncoder, self).__init__() self.sp_cnn = SparseEncoder.dense_model_to_sparse(m=cnn, verbose=verbose, sbn=sbn) self.input_size, self.downsample_raito, self.enc_feat_map_chs = input_size, cnn.get_downsample_ratio(), cnn.get_feature_map_channels() @staticmethod def dense_model_to_sparse(m: nn.Module, verbose=False, sbn=False): oup = m if isinstance(m, nn.Conv2d): m: nn.Conv2d bias = m.bias is not None oup = SparseConv2d( m.in_channels, m.out_channels, kernel_size=m.kernel_size, stride=m.stride, padding=m.padding, dilation=m.dilation, groups=m.groups, bias=bias, padding_mode=m.padding_mode, ) oup.weight.data.copy_(m.weight.data) if bias: oup.bias.data.copy_(m.bias.data) elif isinstance(m, nn.MaxPool2d): m: nn.MaxPool2d oup = SparseMaxPooling(m.kernel_size, stride=m.stride, padding=m.padding, dilation=m.dilation, return_indices=m.return_indices, ceil_mode=m.ceil_mode) elif isinstance(m, nn.AvgPool2d): m: nn.AvgPool2d oup = SparseAvgPooling(m.kernel_size, m.stride, m.padding, ceil_mode=m.ceil_mode, count_include_pad=m.count_include_pad, divisor_override=m.divisor_override) elif isinstance(m, (nn.BatchNorm2d, nn.SyncBatchNorm)): m: nn.BatchNorm2d oup = (SparseSyncBatchNorm2d if sbn else SparseBatchNorm2d)(m.weight.shape[0], eps=m.eps, momentum=m.momentum, affine=m.affine, track_running_stats=m.track_running_stats) oup.weight.data.copy_(m.weight.data) oup.bias.data.copy_(m.bias.data) oup.running_mean.data.copy_(m.running_mean.data) oup.running_var.data.copy_(m.running_var.data) oup.num_batches_tracked.data.copy_(m.num_batches_tracked.data) if hasattr(m, "qconfig"): oup.qconfig = m.qconfig elif isinstance(m, nn.LayerNorm) and not isinstance(m, SparseConvNeXtLayerNorm): m: nn.LayerNorm oup = SparseConvNeXtLayerNorm(m.weight.shape[0], eps=m.eps) oup.weight.data.copy_(m.weight.data) oup.bias.data.copy_(m.bias.data) elif isinstance(m, (nn.Conv1d,)): raise NotImplementedError for name, child in m.named_children(): oup.add_module(name, SparseEncoder.dense_model_to_sparse(child, verbose=verbose, sbn=sbn)) del m return oup def forward(self, x): return self.sp_cnn(x, hierarchical=True)