from typing import List, Tuple import torch from torch import LongTensor, nn, FloatTensor, BoolTensor torch.set_grad_enabled(False) from .dalle_bart_encoder import GLU, AttentionBase class DecoderCrossAttention(AttentionBase): def forward( self, decoder_state: FloatTensor, encoder_state: FloatTensor, attention_mask: BoolTensor ) -> FloatTensor: keys = self.k_proj.forward(encoder_state) values = self.v_proj.forward(encoder_state) queries = self.q_proj.forward(decoder_state) return super().forward(keys, values, queries, attention_mask) class DecoderSelfAttention(AttentionBase): def forward( self, decoder_state: FloatTensor, attention_state: FloatTensor, attention_mask: BoolTensor, token_mask: BoolTensor ) -> Tuple[FloatTensor, FloatTensor]: keys = self.k_proj.forward(decoder_state) values = self.v_proj.forward(decoder_state) queries = self.q_proj.forward(decoder_state) attention_state = torch.where( token_mask[None, :, None], torch.cat([keys, values]), attention_state ) batch_count = decoder_state.shape[0] keys = attention_state[:batch_count] values = attention_state[batch_count:] decoder_state = super().forward(keys, values, queries, attention_mask) return decoder_state, attention_state class DecoderLayer(nn.Module): def __init__( self, image_token_count: int, head_count: int, embed_count: int, glu_embed_count: int ): super().__init__() self.image_token_count = image_token_count self.pre_self_attn_layer_norm = nn.LayerNorm(embed_count) self.self_attn = DecoderSelfAttention(head_count, embed_count) self.self_attn_layer_norm = nn.LayerNorm(embed_count) self.pre_encoder_attn_layer_norm = nn.LayerNorm(embed_count) self.encoder_attn = DecoderCrossAttention(head_count, embed_count) self.encoder_attn_layer_norm = nn.LayerNorm(embed_count) self.glu = GLU(embed_count, glu_embed_count) self.token_indices = torch.arange(self.image_token_count) if torch.cuda.is_available(): self.token_indices = self.token_indices.cuda() def forward( self, decoder_state: FloatTensor, encoder_state: FloatTensor, attention_state: FloatTensor, attention_mask: BoolTensor, token_index: LongTensor ) -> Tuple[FloatTensor, FloatTensor]: # Self Attention residual = decoder_state decoder_state = self.pre_self_attn_layer_norm.forward(decoder_state) self_attn_mask = self.token_indices < token_index + 1 token_mask = self.token_indices == token_index self_attn_mask = torch.stack([self_attn_mask] * decoder_state.shape[0]) decoder_state, attention_state = self.self_attn.forward( decoder_state, attention_state, self_attn_mask, token_mask ) decoder_state = self.self_attn_layer_norm.forward(decoder_state) decoder_state = residual + decoder_state # Cross Attention residual = decoder_state decoder_state = self.pre_encoder_attn_layer_norm.forward(decoder_state) decoder_state = self.encoder_attn.forward( decoder_state, encoder_state, attention_mask ) decoder_state = self.encoder_attn_layer_norm.forward(decoder_state) decoder_state = residual + decoder_state # Feed forward residual = decoder_state decoder_state = self.glu.forward(decoder_state) decoder_state = residual + decoder_state return decoder_state, attention_state class DalleBartDecoder(nn.Module): def __init__( self, image_vocab_count: int, image_token_count: int, sample_token_count: int, embed_count: int, attention_head_count: int, glu_embed_count: int, layer_count: int, batch_count: int, start_token: int ): super().__init__() self.layer_count = layer_count self.sample_token_count = sample_token_count self.condition_factor = 10.0 self.image_token_count = image_token_count self.embed_tokens = nn.Embedding(image_vocab_count + 1, embed_count) self.embed_positions = nn.Embedding(image_token_count, embed_count) self.layers: List[DecoderLayer] = nn.ModuleList([ DecoderLayer( image_token_count, attention_head_count, embed_count, glu_embed_count ) for _ in range(layer_count) ]) self.layernorm_embedding = nn.LayerNorm(embed_count) self.final_ln = nn.LayerNorm(embed_count) self.lm_head = nn.Linear(embed_count, image_vocab_count + 1, bias=False) self.attention_state_shape = ( layer_count, 2 * batch_count, image_token_count, embed_count ) self.zero_prob = torch.zeros([1]) self.token_indices = torch.arange(self.sample_token_count) self.start_token = torch.tensor([start_token]).to(torch.long) if torch.cuda.is_available(): self.zero_prob = self.zero_prob.cuda() self.token_indices = self.token_indices.cuda() self.start_token = self.start_token.cuda() def decode_step( self, text_tokens: LongTensor, encoder_state: FloatTensor, attention_state: FloatTensor, prev_token: LongTensor, token_index: LongTensor ) -> Tuple[LongTensor, FloatTensor]: attention_mask = text_tokens.not_equal(1) batch_count = encoder_state.shape[0] prev_token_batched = torch.cat([prev_token] * batch_count) token_index_batched = torch.cat([token_index] * batch_count) decoder_state = self.embed_tokens.forward(prev_token_batched) decoder_state += self.embed_positions.forward(token_index_batched) decoder_state = self.layernorm_embedding.forward(decoder_state) decoder_state = decoder_state[:, None] attention_states_new = [] for i in range(self.layer_count): decoder_state, attention_state_layer = self.layers[i].forward( decoder_state, encoder_state, attention_state[i], attention_mask, token_index ) attention_states_new.append(attention_state_layer) decoder_state = self.final_ln(decoder_state) logits = self.lm_head(decoder_state) a = self.condition_factor logits: FloatTensor = (1 - a) * logits[0, -1] + a * logits[1, -1] top_logits, _ = logits.topk(50, dim=-1) probs = torch.where( logits < top_logits[-1], self.zero_prob, torch.exp(logits - top_logits[0]) ) return probs, torch.stack(attention_states_new) def forward( self, text_tokens: LongTensor, encoder_state: FloatTensor ) -> LongTensor: image_tokens: List[LongTensor] = [] attention_state = torch.zeros(self.attention_state_shape) if torch.cuda.is_available(): attention_state = attention_state.cuda() image_token = self.start_token for i in range(self.sample_token_count): probs, attention_state = self.decode_step( text_tokens = text_tokens, encoder_state = encoder_state, attention_state = attention_state, prev_token = image_token, token_index = self.token_indices[[i]] ) image_token = torch.multinomial(probs, 1) image_tokens += [image_token] return torch.cat(image_tokens)