backend/nn/unet.py

import math

import torch
from diffusers.configuration_utils import ConfigMixin, register_to_config
from einops import rearrange, repeat
from torch import nn

from backend.attention import attention_function


def checkpoint(f, args, parameters, enable=False):
    if enable:
        raise NotImplementedError("Gradient Checkpointing is not implemented.")
    return f(*args)


def exists(val):
    return val is not None


def default(val, d):
    if exists(val):
        return val
    return d


def conv_nd(dims, *args, **kwargs):
    if dims == 2:
        return nn.Conv2d(*args, **kwargs)
    elif dims == 3:
        return nn.Conv3d(*args, **kwargs)
    else:
        raise ValueError(f"unsupported dimensions: {dims}")


def avg_pool_nd(dims, *args, **kwargs):
    if dims == 1:
        return nn.AvgPool1d(*args, **kwargs)
    elif dims == 2:
        return nn.AvgPool2d(*args, **kwargs)
    elif dims == 3:
        return nn.AvgPool3d(*args, **kwargs)
    raise ValueError(f"unsupported dimensions: {dims}")


def apply_control(h, control, name):
    if control is not None and name in control and len(control[name]) > 0:
        ctrl = control[name].pop()
        if ctrl is not None:
            try:
                h += ctrl
            except:
                print("warning control could not be applied", h.shape, ctrl.shape)
    return h


def timestep_embedding(timesteps, dim, max_period=10000, repeat_only=False):
    # Consistent with Kohya to reduce differences between model training and inference.
    # Will be 0.005% slower than ComfyUI but Forge outweigh image quality than speed.
    if not repeat_only:
        half = dim // 2
        freqs = torch.exp(-math.log(max_period) * torch.arange(start=0, end=half, dtype=torch.float32) / half).to(device=timesteps.device)
        args = timesteps[:, None].float() * freqs[None]
        embedding = torch.cat([torch.cos(args), torch.sin(args)], dim=-1)
        if dim % 2:
            embedding = torch.cat([embedding, torch.zeros_like(embedding[:, :1])], dim=-1)
    else:
        embedding = repeat(timesteps, "b -> b d", d=dim)
    return embedding


class TimestepBlock(nn.Module):
    pass


class TimestepEmbedSequential(nn.Sequential, TimestepBlock):
    def forward(self, x, emb, context=None, transformer_options={}, output_shape=None):
        block_inner_modifiers = transformer_options.get("block_inner_modifiers", [])
        for layer_index, layer in enumerate(self):
            for modifier in block_inner_modifiers:
                x = modifier(x, "before", layer, layer_index, self, transformer_options)
            if isinstance(layer, TimestepBlock):
                x = layer(x, emb, transformer_options)
            elif isinstance(layer, SpatialTransformer):
                x = layer(x, context, transformer_options)
                if "transformer_index" in transformer_options:
                    transformer_options["transformer_index"] += 1
            elif isinstance(layer, Upsample):
                x = layer(x, output_shape=output_shape)
            else:
                x = layer(x)
            for modifier in block_inner_modifiers:
                x = modifier(x, "after", layer, layer_index, self, transformer_options)
        return x


class Timestep(nn.Module):
    def __init__(self, dim):
        super().__init__()
        self.dim = dim

    def forward(self, t):
        return timestep_embedding(t, self.dim)


class GEGLU(nn.Module):
    def __init__(self, dim_in, dim_out):
        super().__init__()
        self.proj = nn.Linear(dim_in, dim_out * 2)

    def forward(self, x):
        x, gate = self.proj(x).chunk(2, dim=-1)
        return x * torch.nn.functional.gelu(gate)


class FeedForward(nn.Module):
    def __init__(self, dim, dim_out=None, mult=4, glu=False, dropout=0.0):
        super().__init__()
        inner_dim = int(dim * mult)
        dim_out = default(dim_out, dim)
        project_in = nn.Sequential(nn.Linear(dim, inner_dim), nn.GELU()) if not glu else GEGLU(dim, inner_dim)
        self.net = nn.Sequential(project_in, nn.Dropout(dropout), nn.Linear(inner_dim, dim_out))

    def forward(self, x):
        return self.net(x)


class CrossAttention(nn.Module):
    def __init__(self, query_dim, context_dim=None, heads=8, dim_head=64, dropout=0.0):
        super().__init__()
        inner_dim = dim_head * heads
        context_dim = default(context_dim, query_dim)
        self.heads = heads
        self.dim_head = dim_head
        self.to_q = nn.Linear(query_dim, inner_dim, bias=False)
        self.to_k = nn.Linear(context_dim, inner_dim, bias=False)
        self.to_v = nn.Linear(context_dim, inner_dim, bias=False)
        self.to_out = nn.Sequential(nn.Linear(inner_dim, query_dim), nn.Dropout(dropout))

    def forward(self, x, context=None, value=None, mask=None, transformer_options={}):
        q = self.to_q(x)
        context = default(context, x)
        k = self.to_k(context)
        if value is not None:
            v = self.to_v(value)
            del value
        else:
            v = self.to_v(context)
        out = attention_function(q, k, v, self.heads, mask)
        return self.to_out(out)


class BasicTransformerBlock(nn.Module):
    def __init__(self, dim, n_heads, d_head, dropout=0.0, context_dim=None, gated_ff=True, checkpoint=True, ff_in=False, inner_dim=None, disable_self_attn=False):
        super().__init__()
        self.ff_in = ff_in or inner_dim is not None
        if inner_dim is None:
            inner_dim = dim
        self.is_res = inner_dim == dim
        if self.ff_in:
            self.norm_in = nn.LayerNorm(dim)
            self.ff_in = FeedForward(dim, dim_out=inner_dim, dropout=dropout, glu=gated_ff)
        self.disable_self_attn = disable_self_attn
        self.attn1 = CrossAttention(query_dim=inner_dim, heads=n_heads, dim_head=d_head, dropout=dropout, context_dim=context_dim if self.disable_self_attn else None)
        self.norm1 = nn.LayerNorm(inner_dim)
        self.attn2 = CrossAttention(query_dim=inner_dim, context_dim=context_dim, heads=n_heads, dim_head=d_head, dropout=dropout)
        self.norm2 = nn.LayerNorm(inner_dim)
        self.ff = FeedForward(inner_dim, dim_out=dim, dropout=dropout, glu=gated_ff)
        self.norm3 = nn.LayerNorm(inner_dim)
        self.checkpoint = checkpoint
        self.n_heads = n_heads
        self.d_head = d_head

    def forward(self, x, context=None, transformer_options={}):
        return checkpoint(self._forward, (x, context, transformer_options), None, self.checkpoint)

    def _forward(self, x, context=None, transformer_options={}):
        # Stolen from ComfyUI with some modifications
        extra_options = {}
        block = transformer_options.get("block", None)
        block_index = transformer_options.get("block_index", 0)
        transformer_patches = {}
        transformer_patches_replace = {}
        for k in transformer_options:
            if k == "patches":
                transformer_patches = transformer_options[k]
            elif k == "patches_replace":
                transformer_patches_replace = transformer_options[k]
            else:
                extra_options[k] = transformer_options[k]
        extra_options["n_heads"] = self.n_heads
        extra_options["dim_head"] = self.d_head
        if self.ff_in:
            x_skip = x
            x = self.ff_in(self.norm_in(x))
            if self.is_res:
                x += x_skip
        n = self.norm1(x)
        if self.disable_self_attn:
            context_attn1 = context
        else:
            context_attn1 = None
        value_attn1 = None
        if "attn1_patch" in transformer_patches:
            patch = transformer_patches["attn1_patch"]
            if context_attn1 is None:
                context_attn1 = n
            value_attn1 = context_attn1
            for p in patch:
                n, context_attn1, value_attn1 = p(n, context_attn1, value_attn1, extra_options)
        if block is not None:
            transformer_block = (block[0], block[1], block_index)
        else:
            transformer_block = None
        attn1_replace_patch = transformer_patches_replace.get("attn1", {})
        block_attn1 = transformer_block
        if block_attn1 not in attn1_replace_patch:
            block_attn1 = block
        if block_attn1 in attn1_replace_patch:
            if context_attn1 is None:
                context_attn1 = n
                value_attn1 = n
            n = self.attn1.to_q(n)
            context_attn1 = self.attn1.to_k(context_attn1)
            value_attn1 = self.attn1.to_v(value_attn1)
            n = attn1_replace_patch[block_attn1](n, context_attn1, value_attn1, extra_options)
            n = self.attn1.to_out(n)
        else:
            n = self.attn1(n, context=context_attn1, value=value_attn1, transformer_options=extra_options)
        if "attn1_output_patch" in transformer_patches:
            patch = transformer_patches["attn1_output_patch"]
            for p in patch:
                n = p(n, extra_options)
        x += n
        if "middle_patch" in transformer_patches:
            patch = transformer_patches["middle_patch"]
            for p in patch:
                x = p(x, extra_options)
        if self.attn2 is not None:
            n = self.norm2(x)
            context_attn2 = context
            value_attn2 = None
            if "attn2_patch" in transformer_patches:
                patch = transformer_patches["attn2_patch"]
                value_attn2 = context_attn2
                for p in patch:
                    n, context_attn2, value_attn2 = p(n, context_attn2, value_attn2, extra_options)
            attn2_replace_patch = transformer_patches_replace.get("attn2", {})
            block_attn2 = transformer_block
            if block_attn2 not in attn2_replace_patch:
                block_attn2 = block
            if block_attn2 in attn2_replace_patch:
                if value_attn2 is None:
                    value_attn2 = context_attn2
                n = self.attn2.to_q(n)
                context_attn2 = self.attn2.to_k(context_attn2)
                value_attn2 = self.attn2.to_v(value_attn2)
                n = attn2_replace_patch[block_attn2](n, context_attn2, value_attn2, extra_options)
                n = self.attn2.to_out(n)
            else:
                n = self.attn2(n, context=context_attn2, value=value_attn2, transformer_options=extra_options)
        if "attn2_output_patch" in transformer_patches:
            patch = transformer_patches["attn2_output_patch"]
            for p in patch:
                n = p(n, extra_options)
        x += n
        x_skip = 0
        if self.is_res:
            x_skip = x
        x = self.ff(self.norm3(x))
        if self.is_res:
            x += x_skip
        return x


class SpatialTransformer(nn.Module):
    def __init__(self, in_channels, n_heads, d_head, depth=1, dropout=0.0, context_dim=None, disable_self_attn=False, use_linear=False, use_checkpoint=True):
        super().__init__()
        if exists(context_dim) and not isinstance(context_dim, list):
            context_dim = [context_dim] * depth
        self.in_channels = in_channels
        inner_dim = n_heads * d_head
        self.norm = nn.GroupNorm(num_groups=32, num_channels=in_channels, eps=1e-6, affine=True)
        if not use_linear:
            self.proj_in = nn.Conv2d(in_channels, inner_dim, kernel_size=1, stride=1, padding=0)
        else:
            self.proj_in = nn.Linear(in_channels, inner_dim)
        self.transformer_blocks = nn.ModuleList([BasicTransformerBlock(inner_dim, n_heads, d_head, dropout=dropout, context_dim=context_dim[d], disable_self_attn=disable_self_attn, checkpoint=use_checkpoint) for d in range(depth)])
        if not use_linear:
            self.proj_out = nn.Conv2d(inner_dim, in_channels, kernel_size=1, stride=1, padding=0)
        else:
            self.proj_out = nn.Linear(in_channels, inner_dim)
        self.use_linear = use_linear

    def forward(self, x, context=None, transformer_options={}):
        if not isinstance(context, list):
            context = [context] * len(self.transformer_blocks)
        b, c, h, w = x.shape
        x_in = x
        x = self.norm(x)
        if not self.use_linear:
            x = self.proj_in(x)
        x = rearrange(x, "b c h w -> b (h w) c").contiguous()
        if self.use_linear:
            x = self.proj_in(x)
        for i, block in enumerate(self.transformer_blocks):
            transformer_options["block_index"] = i
            x = block(x, context=context[i], transformer_options=transformer_options)
        if self.use_linear:
            x = self.proj_out(x)
        x = rearrange(x, "b (h w) c -> b c h w", h=h, w=w).contiguous()
        if not self.use_linear:
            x = self.proj_out(x)
        return x + x_in


class Upsample(nn.Module):
    def __init__(self, channels, use_conv, dims=2, out_channels=None, padding=1):
        super().__init__()
        self.channels = channels
        self.out_channels = out_channels or channels
        self.use_conv = use_conv
        self.dims = dims
        if use_conv:
            self.conv = conv_nd(dims, self.channels, self.out_channels, 3, padding=padding)

    def forward(self, x, output_shape=None):
        assert x.shape[1] == self.channels
        if self.dims == 3:
            shape = [x.shape[2], x.shape[3] * 2, x.shape[4] * 2]
            if output_shape is not None:
                shape[1] = output_shape[3]
                shape[2] = output_shape[4]
        else:
            shape = [x.shape[2] * 2, x.shape[3] * 2]
            if output_shape is not None:
                shape[0] = output_shape[2]
                shape[1] = output_shape[3]
        x = torch.nn.functional.interpolate(x, size=shape, mode="nearest")
        if self.use_conv:
            x = self.conv(x)
        return x


class Downsample(nn.Module):
    def __init__(self, channels, use_conv, dims=2, out_channels=None, padding=1):
        super().__init__()
        self.channels = channels
        self.out_channels = out_channels or channels
        self.use_conv = use_conv
        self.dims = dims
        stride = 2 if dims != 3 else (1, 2, 2)
        if use_conv:
            self.op = conv_nd(dims, self.channels, self.out_channels, 3, stride=stride, padding=padding)
        else:
            assert self.channels == self.out_channels
            self.op = avg_pool_nd(dims, kernel_size=stride, stride=stride)

    def forward(self, x):
        assert x.shape[1] == self.channels
        return self.op(x)


class ResBlock(TimestepBlock):
    def __init__(self, channels, emb_channels, dropout, out_channels=None, use_conv=False, use_scale_shift_norm=False, dims=2, use_checkpoint=False, up=False, down=False, kernel_size=3, exchange_temb_dims=False, skip_t_emb=False):
        super().__init__()
        self.channels = channels
        self.emb_channels = emb_channels
        self.dropout = dropout
        self.out_channels = out_channels or channels
        self.use_conv = use_conv
        self.use_checkpoint = use_checkpoint
        self.use_scale_shift_norm = use_scale_shift_norm
        self.exchange_temb_dims = exchange_temb_dims
        if isinstance(kernel_size, list):
            padding = [k // 2 for k in kernel_size]
        else:
            padding = kernel_size // 2
        self.in_layers = nn.Sequential(
            nn.GroupNorm(32, channels),
            nn.SiLU(),
            conv_nd(dims, channels, self.out_channels, kernel_size, padding=padding),
        )
        self.updown = up or down
        if up:
            self.h_upd = Upsample(channels, False, dims)
            self.x_upd = Upsample(channels, False, dims)
        elif down:
            self.h_upd = Downsample(channels, False, dims)
            self.x_upd = Downsample(channels, False, dims)
        else:
            self.h_upd = self.x_upd = nn.Identity()
        self.skip_t_emb = skip_t_emb
        if self.skip_t_emb:
            self.emb_layers = None
            self.exchange_temb_dims = False
        else:
            self.emb_layers = nn.Sequential(
                nn.SiLU(),
                nn.Linear(emb_channels, 2 * self.out_channels if use_scale_shift_norm else self.out_channels),
            )
        self.out_layers = nn.Sequential(nn.GroupNorm(32, self.out_channels), nn.SiLU(), nn.Dropout(p=dropout), conv_nd(dims, self.out_channels, self.out_channels, kernel_size, padding=padding))
        if self.out_channels == channels:
            self.skip_connection = nn.Identity()
        elif use_conv:
            self.skip_connection = conv_nd(dims, channels, self.out_channels, kernel_size, padding=padding)
        else:
            self.skip_connection = conv_nd(dims, channels, self.out_channels, 1)

    def forward(self, x, emb, transformer_options={}):
        return checkpoint(self._forward, (x, emb, transformer_options), None, self.use_checkpoint)

    def _forward(self, x, emb, transformer_options={}):
        if self.updown:
            in_rest, in_conv = self.in_layers[:-1], self.in_layers[-1]
            if "group_norm_wrapper" in transformer_options:
                in_norm, in_rest = in_rest[0], in_rest[1:]
                h = transformer_options["group_norm_wrapper"](in_norm, x, transformer_options)
                h = in_rest(h)
            else:
                h = in_rest(x)
            h = self.h_upd(h)
            x = self.x_upd(x)
            h = in_conv(h)
        else:
            if "group_norm_wrapper" in transformer_options:
                in_norm = self.in_layers[0]
                h = transformer_options["group_norm_wrapper"](in_norm, x, transformer_options)
                h = self.in_layers[1:](h)
            else:
                h = self.in_layers(x)
        emb_out = None
        if not self.skip_t_emb:
            emb_out = self.emb_layers(emb).type(h.dtype)
            while len(emb_out.shape) < len(h.shape):
                emb_out = emb_out[..., None]
        if self.use_scale_shift_norm:
            out_norm, out_rest = self.out_layers[0], self.out_layers[1:]
            if "group_norm_wrapper" in transformer_options:
                h = transformer_options["group_norm_wrapper"](out_norm, h, transformer_options)
            else:
                h = out_norm(h)
            if emb_out is not None:
                scale, shift = torch.chunk(emb_out, 2, dim=1)
                h *= 1 + scale
                h += shift
            h = out_rest(h)
        else:
            if emb_out is not None:
                if self.exchange_temb_dims:
                    emb_out = rearrange(emb_out, "b t c ... -> b c t ...")
                h = h + emb_out
            if "group_norm_wrapper" in transformer_options:
                h = transformer_options["group_norm_wrapper"](self.out_layers[0], h, transformer_options)
                h = self.out_layers[1:](h)
            else:
                h = self.out_layers(h)
        return self.skip_connection(x) + h


class IntegratedUNet2DConditionModel(nn.Module, ConfigMixin):
    config_name = "config.json"

    @register_to_config
    def __init__(self, in_channels, model_channels, out_channels, num_res_blocks, dropout=0, channel_mult=(1, 2, 4, 8), conv_resample=True, dims=2, num_classes=None, use_checkpoint=False, num_heads=-1, num_head_channels=-1, use_scale_shift_norm=False, resblock_updown=False, use_spatial_transformer=False, transformer_depth=1, context_dim=None, disable_self_attentions=None, num_attention_blocks=None, disable_middle_self_attn=False, use_linear_in_transformer=False, adm_in_channels=None, transformer_depth_middle=None, transformer_depth_output=None):
        super().__init__()
        if context_dim is not None:
            assert use_spatial_transformer
        if num_heads == -1:
            assert num_head_channels != -1
        if num_head_channels == -1:
            assert num_heads != -1
        self.in_channels = in_channels
        self.model_channels = model_channels
        self.out_channels = out_channels
        if isinstance(num_res_blocks, int):
            self.num_res_blocks = len(channel_mult) * [num_res_blocks]
        else:
            self.num_res_blocks = num_res_blocks
        if disable_self_attentions is not None:
            assert len(disable_self_attentions) == len(channel_mult)
        if num_attention_blocks is not None:
            assert len(num_attention_blocks) == len(self.num_res_blocks)
        transformer_depth = transformer_depth[:]
        transformer_depth_output = transformer_depth_output[:]
        self.dropout = dropout
        self.channel_mult = channel_mult
        self.conv_resample = conv_resample
        self.num_classes = num_classes
        self.use_checkpoint = use_checkpoint
        self.num_heads = num_heads
        self.num_head_channels = num_head_channels
        time_embed_dim = model_channels * 4
        self.time_embed = nn.Sequential(
            nn.Linear(model_channels, time_embed_dim),
            nn.SiLU(),
            nn.Linear(time_embed_dim, time_embed_dim),
        )
        if self.num_classes is not None:
            if isinstance(self.num_classes, int):
                self.label_emb = nn.Embedding(num_classes, time_embed_dim)
            elif self.num_classes == "continuous":
                self.label_emb = nn.Linear(1, time_embed_dim)
            elif self.num_classes == "sequential":
                assert adm_in_channels is not None
                self.label_emb = nn.Sequential(
                    nn.Sequential(
                        nn.Linear(adm_in_channels, time_embed_dim),
                        nn.SiLU(),
                        nn.Linear(time_embed_dim, time_embed_dim),
                    )
                )
            else:
                raise ValueError("Bad ADM")
        self.input_blocks = nn.ModuleList([TimestepEmbedSequential(conv_nd(dims, in_channels, model_channels, 3, padding=1))])
        self._feature_size = model_channels
        input_block_chans = [model_channels]
        ch = model_channels
        ds = 1
        for level, mult in enumerate(channel_mult):
            for nr in range(self.num_res_blocks[level]):
                layers = [
                    ResBlock(
                        channels=ch,
                        emb_channels=time_embed_dim,
                        dropout=dropout,
                        out_channels=mult * model_channels,
                        dims=dims,
                        use_checkpoint=use_checkpoint,
                        use_scale_shift_norm=use_scale_shift_norm,
                    )
                ]
                ch = mult * model_channels
                num_transformers = transformer_depth.pop(0)
                if num_transformers > 0:
                    if num_head_channels == -1:
                        dim_head = ch // num_heads
                    else:
                        num_heads = ch // num_head_channels
                        dim_head = num_head_channels
                    if exists(disable_self_attentions):
                        disabled_sa = disable_self_attentions[level]
                    else:
                        disabled_sa = False
                    if not exists(num_attention_blocks) or nr < num_attention_blocks[level]:
                        layers.append(SpatialTransformer(ch, num_heads, dim_head, depth=num_transformers, context_dim=context_dim, disable_self_attn=disabled_sa, use_checkpoint=use_checkpoint, use_linear=use_linear_in_transformer))
                self.input_blocks.append(TimestepEmbedSequential(*layers))
                self._feature_size += ch
                input_block_chans.append(ch)
            if level != len(channel_mult) - 1:
                out_ch = ch
                self.input_blocks.append(
                    TimestepEmbedSequential(
                        ResBlock(
                            channels=ch,
                            emb_channels=time_embed_dim,
                            dropout=dropout,
                            out_channels=out_ch,
                            dims=dims,
                            use_checkpoint=use_checkpoint,
                            use_scale_shift_norm=use_scale_shift_norm,
                            down=True,
                        )
                        if resblock_updown
                        else Downsample(ch, conv_resample, dims=dims, out_channels=out_ch)
                    )
                )
                ch = out_ch
                input_block_chans.append(ch)
                ds *= 2
                self._feature_size += ch
        if num_head_channels == -1:
            dim_head = ch // num_heads
        else:
            num_heads = ch // num_head_channels
            dim_head = num_head_channels
        mid_block = [
            ResBlock(
                channels=ch,
                emb_channels=time_embed_dim,
                dropout=dropout,
                out_channels=None,
                dims=dims,
                use_checkpoint=use_checkpoint,
                use_scale_shift_norm=use_scale_shift_norm,
            )
        ]
        if transformer_depth_middle >= 0:
            mid_block += [
                SpatialTransformer(ch, num_heads, dim_head, depth=transformer_depth_middle, context_dim=context_dim, disable_self_attn=disable_middle_self_attn, use_checkpoint=use_checkpoint, use_linear=use_linear_in_transformer),
                ResBlock(
                    channels=ch,
                    emb_channels=time_embed_dim,
                    dropout=dropout,
                    out_channels=None,
                    dims=dims,
                    use_checkpoint=use_checkpoint,
                    use_scale_shift_norm=use_scale_shift_norm,
                ),
            ]
        self.middle_block = TimestepEmbedSequential(*mid_block)
        self._feature_size += ch
        self.output_blocks = nn.ModuleList([])
        for level, mult in list(enumerate(channel_mult))[::-1]:
            for i in range(self.num_res_blocks[level] + 1):
                ich = input_block_chans.pop()
                layers = [
                    ResBlock(
                        channels=ch + ich,
                        emb_channels=time_embed_dim,
                        dropout=dropout,
                        out_channels=model_channels * mult,
                        dims=dims,
                        use_checkpoint=use_checkpoint,
                        use_scale_shift_norm=use_scale_shift_norm,
                    )
                ]
                ch = model_channels * mult
                num_transformers = transformer_depth_output.pop()
                if num_transformers > 0:
                    if num_head_channels == -1:
                        dim_head = ch // num_heads
                    else:
                        num_heads = ch // num_head_channels
                        dim_head = num_head_channels
                    if exists(disable_self_attentions):
                        disabled_sa = disable_self_attentions[level]
                    else:
                        disabled_sa = False
                    if not exists(num_attention_blocks) or i < num_attention_blocks[level]:
                        layers.append(SpatialTransformer(ch, num_heads, dim_head, depth=num_transformers, context_dim=context_dim, disable_self_attn=disabled_sa, use_checkpoint=use_checkpoint, use_linear=use_linear_in_transformer))
                if level and i == self.num_res_blocks[level]:
                    out_ch = ch
                    layers.append(
                        ResBlock(
                            channels=ch,
                            emb_channels=time_embed_dim,
                            dropout=dropout,
                            out_channels=out_ch,
                            dims=dims,
                            use_checkpoint=use_checkpoint,
                            use_scale_shift_norm=use_scale_shift_norm,
                            up=True,
                        )
                        if resblock_updown
                        else Upsample(ch, conv_resample, dims=dims, out_channels=out_ch)
                    )
                    ds //= 2
                self.output_blocks.append(TimestepEmbedSequential(*layers))
                self._feature_size += ch
        self.out = nn.Sequential(
            nn.GroupNorm(32, ch),
            nn.SiLU(),
            conv_nd(dims, model_channels, out_channels, 3, padding=1),
        )

    def forward(self, x, timesteps=None, context=None, y=None, control=None, transformer_options={}, **kwargs):
        transformer_options["original_shape"] = list(x.shape)
        transformer_options["transformer_index"] = 0
        transformer_patches = transformer_options.get("patches", {})
        block_modifiers = transformer_options.get("block_modifiers", [])
        assert (y is not None) == (self.num_classes is not None)
        hs = []
        t_emb = timestep_embedding(timesteps, self.model_channels, repeat_only=False).to(x.dtype)
        emb = self.time_embed(t_emb)
        if self.num_classes is not None:
            assert y.shape[0] == x.shape[0]
            emb = emb + self.label_emb(y)
        h = x
        for id, module in enumerate(self.input_blocks):
            transformer_options["block"] = ("input", id)
            for block_modifier in block_modifiers:
                h = block_modifier(h, "before", transformer_options)
            h = module(h, emb, context, transformer_options)
            h = apply_control(h, control, "input")
            for block_modifier in block_modifiers:
                h = block_modifier(h, "after", transformer_options)
            if "input_block_patch" in transformer_patches:
                patch = transformer_patches["input_block_patch"]
                for p in patch:
                    h = p(h, transformer_options)
            hs.append(h)
            if "input_block_patch_after_skip" in transformer_patches:
                patch = transformer_patches["input_block_patch_after_skip"]
                for p in patch:
                    h = p(h, transformer_options)
        transformer_options["block"] = ("middle", 0)
        for block_modifier in block_modifiers:
            h = block_modifier(h, "before", transformer_options)
        h = self.middle_block(h, emb, context, transformer_options)
        h = apply_control(h, control, "middle")
        for block_modifier in block_modifiers:
            h = block_modifier(h, "after", transformer_options)
        for id, module in enumerate(self.output_blocks):
            transformer_options["block"] = ("output", id)
            hsp = hs.pop()
            hsp = apply_control(hsp, control, "output")
            if "output_block_patch" in transformer_patches:
                patch = transformer_patches["output_block_patch"]
                for p in patch:
                    h, hsp = p(h, hsp, transformer_options)
            h = torch.cat([h, hsp], dim=1)
            del hsp
            if len(hs) > 0:
                output_shape = hs[-1].shape
            else:
                output_shape = None
            for block_modifier in block_modifiers:
                h = block_modifier(h, "before", transformer_options)
            h = module(h, emb, context, transformer_options, output_shape)
            for block_modifier in block_modifiers:
                h = block_modifier(h, "after", transformer_options)
        transformer_options["block"] = ("last", 0)
        for block_modifier in block_modifiers:
            h = block_modifier(h, "before", transformer_options)
        if "group_norm_wrapper" in transformer_options:
            out_norm, out_rest = self.out[0], self.out[1:]
            h = transformer_options["group_norm_wrapper"](out_norm, h, transformer_options)
            h = out_rest(h)
        else:
            h = self.out(h)
        for block_modifier in block_modifiers:
            h = block_modifier(h, "after", transformer_options)
        return h.type(x.dtype)