Add OPT

cacheflow/worker/models/__init__.py

+from cacheflow.worker.models.opt import OPTForCausalLM
+
+__all__ = [
+    'OPTForCausalLM',
+]

cacheflow/worker/models/opt.py

+"""1D OPT model compatible with HuggingFace weights."""
+import torch
+from torch import nn
+from transformers import OPTConfig
+from transformers import PreTrainedModel
+
+
+class OPTLearnedPositionalEmbedding(nn.Embedding):
+
+    def __init__(self, num_embeddings: int, embedding_dim: int):
+        # OPT is set up so that if padding_idx is specified then offset the embedding ids by 2
+        # and adjust num_embeddings appropriately. Other models don't have this hack
+        self.offset = 2
+        super().__init__(num_embeddings + self.offset, embedding_dim)
+
+    def forward(self, positions: torch.LongTensor):
+        return super().forward(positions + self.offset)
+
+
+class OPTAttention(nn.Module):
+
+    def __init__(
+        self,
+        embed_dim: int,
+        num_heads: int,
+        bias: bool = True,
+    ) -> None:
+        super().__init__()
+        self.embed_dim = embed_dim
+        self.num_heads = num_heads
+        self.head_dim = embed_dim // num_heads
+        self.scaling = self.head_dim**-0.5
+
+        self.k_proj = nn.Linear(embed_dim, embed_dim, bias=bias)
+        self.v_proj = nn.Linear(embed_dim, embed_dim, bias=bias)
+        self.q_proj = nn.Linear(embed_dim, embed_dim, bias=bias)
+        self.out_proj = nn.Linear(embed_dim, embed_dim, bias=bias)
+
+    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
+        q = self.q_proj(hidden_states) * self.scaling
+        k = self.k_proj(hidden_states)
+        v = self.v_proj(hidden_states)
+        # TODO
+        attn_output = None
+        output = self.out_proj(attn_output)
+        return output
+
+
+class OPTDecoderLayer(nn.Module):
+
+    def __init__(self, config: OPTConfig):
+        super().__init__()
+        self.embed_dim = config.hidden_size
+        self.self_attn = OPTAttention(
+            embed_dim=self.embed_dim,
+            num_heads=config.num_attention_heads,
+            bias=config.enable_bias,
+        )
+        self.do_layer_norm_before = config.do_layer_norm_before
+        assert config.activation_function == 'relu'
+        self.activation_fn = nn.ReLU()
+
+        self.self_attn_layer_norm = nn.LayerNorm(
+            self.embed_dim, elementwise_affine=config.layer_norm_elementwise_affine)
+        self.fc1 = nn.Linear(self.embed_dim, config.ffn_dim, bias=config.enable_bias)
+        self.fc2 = nn.Linear(config.ffn_dim, self.embed_dim, bias=config.enable_bias)
+        self.final_layer_norm = nn.LayerNorm(self.embed_dim, elementwise_affine=config.layer_norm_elementwise_affine)
+
+    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
+        # Self Attention
+        residual = hidden_states
+        # 125m, 1.7B, ..., 175B applies layer norm BEFORE attention
+        if self.do_layer_norm_before:
+            hidden_states = self.self_attn_layer_norm(hidden_states)
+        hidden_states = self.self_attn(hidden_states=hidden_states)
+        hidden_states = residual + hidden_states
+        # 350m applies layer norm AFTER attention
+        if not self.do_layer_norm_before:
+            hidden_states = self.self_attn_layer_norm(hidden_states)
+
+        # Fully Connected
+        residual = hidden_states
+        # 125m, 1.7B, ..., 175B applies layer norm BEFORE attention
+        if self.do_layer_norm_before:
+            hidden_states = self.final_layer_norm(hidden_states)
+        hidden_states = self.fc1(hidden_states)
+        hidden_states = self.activation_fn(hidden_states)
+        hidden_states = self.fc2(hidden_states)
+        hidden_states = residual + hidden_states
+        # 350m applies layer norm AFTER attention
+        if not self.do_layer_norm_before:
+            hidden_states = self.final_layer_norm(hidden_states)
+        return hidden_states
+
+
+class OPTPreTrainedModel(PreTrainedModel):
+    config_class = OPTConfig
+    base_model_prefix = "model"
+    supports_gradient_checkpointing = True
+    _no_split_modules = ["OPTDecoderLayer"]
+    _keys_to_ignore_on_load_unexpected = [r"decoder\.version"]
+
+    def _init_weights(self, module) -> None:
+        del module  # unused
+        return
+
+
+class OPTDecoder(OPTPreTrainedModel):
+
+    def __init__(self, config: OPTConfig):
+        super().__init__(config)
+        self.padding_idx = config.pad_token_id
+        self.max_target_positions = config.max_position_embeddings
+        self.vocab_size = config.vocab_size
+
+        self.embed_tokens = nn.Embedding(config.vocab_size, config.word_embed_proj_dim, self.padding_idx)
+        self.embed_positions = OPTLearnedPositionalEmbedding(config.max_position_embeddings, config.hidden_size)
+
+        if config.word_embed_proj_dim != config.hidden_size:
+            self.project_out = nn.Linear(config.hidden_size, config.word_embed_proj_dim, bias=False)
+        else:
+            self.project_out = None
+
+        if config.word_embed_proj_dim != config.hidden_size:
+            self.project_in = nn.Linear(config.word_embed_proj_dim, config.hidden_size, bias=False)
+        else:
+            self.project_in = None
+
+        # Note that the only purpose of `config._remove_final_layer_norm` is to keep backward compatibility
+        # with checkpoints that have been fine-tuned before transformers v4.20.1
+        # see https://github.com/facebookresearch/metaseq/pull/164
+        if config.do_layer_norm_before and not config._remove_final_layer_norm:
+            self.final_layer_norm = nn.LayerNorm(
+                config.hidden_size, elementwise_affine=config.layer_norm_elementwise_affine
+            )
+        else:
+            self.final_layer_norm = None
+
+        self.layers = nn.ModuleList([OPTDecoderLayer(config) for _ in range(config.num_hidden_layers)])
+
+        # Initialize weights and apply final processing
+        self.post_init()
+
+    def forward(
+        self,
+        input_ids: torch.LongTensor,
+        positions: torch.LongTensor,
+    ) -> torch.Tensor:
+        inputs_embeds = self.embed_tokens(input_ids)
+        pos_embeds = self.embed_positions(positions)
+        pos_embeds = None
+        if self.project_in is not None:
+            inputs_embeds = self.project_in(inputs_embeds)
+        hidden_states = inputs_embeds + pos_embeds
+
+        for layer in self.layers:
+            hidden_states = layer(hidden_states)
+
+        if self.final_layer_norm is not None:
+            hidden_states = self.final_layer_norm(hidden_states)
+        if self.project_out is not None:
+            hidden_states = self.project_out(hidden_states)
+        return hidden_states
+
+
+class OPTModel(OPTPreTrainedModel):
+
+    def __init__(self, config: OPTConfig):
+        super().__init__(config)
+        self.decoder = OPTDecoder(config)
+        # Initialize weights and apply final processing
+        self.post_init()
+
+    def forward(
+        self,
+        input_ids: torch.LongTensor,
+        positions: torch.LongTensor,
+    ) -> torch.Tensor:
+        return self.decoder(input_ids, positions)
+
+
+class OPTForCausalLM(OPTPreTrainedModel):
+    _keys_to_ignore_on_load_missing = [r"lm_head.weight"]
+
+    def __init__(self, config):
+        super().__init__(config)
+        self.model = OPTModel(config)
+
+        # the lm_head weight is automatically tied to the embed tokens weight
+        self.lm_head = nn.Linear(config.word_embed_proj_dim, config.vocab_size, bias=False)
+
+        # Initialize weights and apply final processing
+        self.post_init()
+
+    def forward(
+        self,
+        input_ids: torch.LongTensor,
+        positions: torch.LongTensor,
+    ) -> torch.Tensor:
+        hidden_states = self.model.decoder(input_ids, positions)
+        logits = self.lm_head(hidden_states).contiguous()
+        return logits