import torch from torch import nn from argparse import Namespace import xformers.ops as xops from transformers.activations import ACT2FN class PatchEmbedding(nn.Module): def __init__(self, config): super().__init__() self.proj = nn.Conv2d(config.in_channels, config.hidden_size, kernel_size=config.patch_size, stride=config.patch_size) self.cls_embedding = nn.Parameter(torch.zeros(1, config.hidden_size)) self.position_embedding = nn.Embedding(config.num_positions, config.hidden_size) def forward(self, images: "tensor(B, C, H, W)") -> "tensor(B, L, D)": x = self.proj(images) x = x.flatten(2).transpose(1, 2) cls_token = self.cls_embedding.expand(x.shape[0], -1, -1) x = torch.cat((cls_token, x), dim=1) x += self.position_embedding.weight.unsqueeze(0) return x class Attention(nn.Module): def __init__(self, config): super().__init__() self.num_heads = config.num_heads head_dim = config.hidden_size // config.num_heads self.scale = head_dim ** -0.5 self.query_key_value = nn.Linear(config.hidden_size, config.hidden_size * 3) self.dense = nn.Linear(config.hidden_size, config.hidden_size) self.output_dropout = torch.nn.Dropout(config.dropout_prob) def forward(self, x: "tensor(B, L, D)") -> "tensor(B, L, D)": B, L, _ = x.shape qkv = self.query_key_value(x) qkv = qkv.reshape(B, L, 3, self.num_heads, -1).permute(2, 0, 1, 3, 4) # 3, B, L, H, D q, k, v = qkv[0], qkv[1], qkv[2] out = xops.memory_efficient_attention( q, k, v, scale=self.scale, ) output = self.dense(out.view(B, L, -1)) output = self.output_dropout(output) return output def attention(self, q, k, v): attn_weights = torch.matmul(q * self.scale, k.transpose(-2, -1)) attn_weights = attn_weights.softmax(dim=-1) output = torch.matmul(attn_weights, v) return output class MLP(nn.Module): def __init__(self, config): super().__init__() self.config = config self.activation_fn = ACT2FN[config.hidden_act] self.fc1 = nn.Linear(config.hidden_size, config.intermediate_size) self.fc2 = nn.Linear(config.intermediate_size, config.hidden_size) def forward(self, x: torch.Tensor) -> torch.Tensor: x = self.fc1(x) x = self.activation_fn(x) x = self.fc2(x) return x class TransformerLayer(nn.Module): def __init__(self, config): super().__init__() self.input_layernorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps) self.attention = Attention(config) self.mlp = MLP(config) self.post_attention_layernorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps) def forward(self, hidden_states): attention_input = hidden_states attention_output = self.input_layernorm(self.attention(attention_input)) hidden_states = attention_input + attention_output mlp_input = hidden_states mlp_output = self.post_attention_layernorm(self.mlp(mlp_input)) output = mlp_input + mlp_output return output class Transformer(nn.Module): def __init__(self, config): super().__init__() self.layers = nn.ModuleList([TransformerLayer(config) for _ in range(config.num_hidden_layers)]) def forward(self, hidden_states): for layer_module in self.layers: hidden_states = layer_module(hidden_states) return hidden_states class GLU(nn.Module): def __init__(self, config, in_features): super().__init__() self.linear_proj = nn.Linear(in_features, config.hidden_size, bias=False) self.norm1 = nn.LayerNorm(config.hidden_size) self.act1 = nn.GELU() self.act2 = nn.functional.silu self.dense_h_to_4h = nn.Linear(config.hidden_size, config.intermediate_size, bias=False) self.gate_proj = nn.Linear(config.hidden_size, config.intermediate_size, bias=False) self.dense_4h_to_h = nn.Linear(config.intermediate_size, config.hidden_size, bias=False) def forward(self, x): x = self.linear_proj(x) x = self.act1(self.norm1(x)) x = self.act2(self.gate_proj(x)) * self.dense_h_to_4h(x) x = self.dense_4h_to_h(x) return x class EVA2CLIPModel(nn.Module): def __init__(self, config): super().__init__() vision_config = Namespace(**config.vision_config) self.patch_embedding = PatchEmbedding(vision_config) self.transformer = Transformer(vision_config) self.linear_proj = GLU(config, in_features=vision_config.hidden_size) self.boi = nn.Parameter(torch.zeros(1, 1, config.hidden_size)) self.eoi = nn.Parameter(torch.zeros(1, 1, config.hidden_size)) self.pos_embed = nn.Parameter(torch.zeros((vision_config.image_size // vision_config.patch_size) ** 2, vision_config.hidden_size)) def forward(self, images: "tensor(B, C, H, W)") -> "tensor(B, L, D)": x = self.patch_embedding(images) x = self.transformer(x) x = x[:, 1:] x = self.linear_proj(x + self.pos_embed.unsqueeze(0)) boi = self.boi.expand(x.shape[0], -1, -1) eoi = self.eoi.expand(x.shape[0], -1, -1) x = torch.cat((boi, x, eoi), dim=1) return x