354 lines
16 KiB
Python
354 lines
16 KiB
Python
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# coding=utf-8
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# Copyright 2024 Cohere team. All rights reserved.
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#
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# This code is based on EleutherAI's GPT-NeoX library and the GPT-NeoX
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# and OPT implementations in this library. It has been modified from its
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# original forms to accommodate minor architectural differences compared
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# to GPT-NeoX and OPT used by the Meta AI team that trained the model.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# This file is based on the LLama model definition file in transformers
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"""PyTorch Cohere model."""
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from typing import Callable, Optional, Union
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import torch
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import torch.utils.checkpoint
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from torch import nn
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from ...cache_utils import Cache
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from ...modeling_flash_attention_utils import FlashAttentionKwargs
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from ...modeling_layers import GradientCheckpointingLayer
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from ...modeling_outputs import BaseModelOutputWithPast, CausalLMOutputWithPast
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from ...modeling_rope_utils import dynamic_rope_update
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from ...modeling_utils import ALL_ATTENTION_FUNCTIONS
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from ...processing_utils import Unpack
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from ...utils import TransformersKwargs, logging
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from ..llama.modeling_llama import (
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LlamaAttention,
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LlamaForCausalLM,
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LlamaMLP,
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LlamaModel,
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LlamaRotaryEmbedding,
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eager_attention_forward,
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)
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from .configuration_cohere import CohereConfig
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logger = logging.get_logger(__name__)
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class CohereLayerNorm(nn.Module):
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def __init__(self, hidden_size=None, eps=1e-5, bias=False):
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"""The hidden size can be a tuple or an int. The tuple is used for QKNorm to normalize across head_dim"""
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super().__init__()
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self.weight = nn.Parameter(torch.ones(hidden_size))
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self.variance_epsilon = eps
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def forward(self, hidden_states):
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input_dtype = hidden_states.dtype
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hidden_states = hidden_states.to(torch.float32)
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mean = hidden_states.mean(-1, keepdim=True)
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variance = (hidden_states - mean).pow(2).mean(-1, keepdim=True)
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hidden_states = (hidden_states - mean) * torch.rsqrt(variance + self.variance_epsilon)
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hidden_states = self.weight.to(torch.float32) * hidden_states
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return hidden_states.to(input_dtype)
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class CohereRotaryEmbedding(LlamaRotaryEmbedding):
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@torch.no_grad()
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@dynamic_rope_update # power user: used with advanced RoPE types (e.g. dynamic rope)
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def forward(self, x, position_ids):
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inv_freq_expanded = self.inv_freq[None, :, None].float().expand(position_ids.shape[0], -1, 1)
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position_ids_expanded = position_ids[:, None, :].float()
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device_type = x.device.type if isinstance(x.device.type, str) and x.device.type != "mps" else "cpu"
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with torch.autocast(device_type=device_type, enabled=False): # Force float32
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freqs = (inv_freq_expanded.float() @ position_ids_expanded.float()).transpose(1, 2)
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emb = torch.repeat_interleave(freqs, 2, dim=-1) # diff from Llama: we interleave() instead of cat()
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cos = emb.cos() * self.attention_scaling
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sin = emb.sin() * self.attention_scaling
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return cos.to(dtype=x.dtype), sin.to(dtype=x.dtype)
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def rotate_half(x):
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# Split and rotate. Note that this function is different from e.g. Llama.
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x1 = x[..., ::2]
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x2 = x[..., 1::2]
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rot_x = torch.stack([-x2, x1], dim=-1).flatten(-2)
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return rot_x
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def apply_rotary_pos_emb(q, k, cos, sin, position_ids=None, unsqueeze_dim=1):
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"""Applies Rotary Position Embedding to the query and key tensors.
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Args:
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q (`torch.Tensor`): The query tensor.
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k (`torch.Tensor`): The key tensor.
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cos (`torch.Tensor`): The cosine part of the rotary embedding.
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sin (`torch.Tensor`): The sine part of the rotary embedding.
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position_ids (`torch.Tensor`, *optional*):
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Deprecated and unused.
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unsqueeze_dim (`int`, *optional*, defaults to 1):
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The 'unsqueeze_dim' argument specifies the dimension along which to unsqueeze cos[position_ids] and
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sin[position_ids] so that they can be properly broadcasted to the dimensions of q and k. For example, note
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that cos[position_ids] and sin[position_ids] have the shape [batch_size, seq_len, head_dim]. Then, if q and
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k have the shape [batch_size, heads, seq_len, head_dim], then setting unsqueeze_dim=1 makes
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cos[position_ids] and sin[position_ids] broadcastable to the shapes of q and k. Similarly, if q and k have
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the shape [batch_size, seq_len, heads, head_dim], then set unsqueeze_dim=2.
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Returns:
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`tuple(torch.Tensor)` comprising of the query and key tensors rotated using the Rotary Position Embedding.
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"""
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dtype = q.dtype
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q = q.float()
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k = k.float()
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cos = cos.unsqueeze(unsqueeze_dim)
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sin = sin.unsqueeze(unsqueeze_dim)
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q_embed = (q * cos) + (rotate_half(q) * sin)
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k_embed = (k * cos) + (rotate_half(k) * sin)
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return q_embed.to(dtype=dtype), k_embed.to(dtype=dtype)
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class CohereMLP(LlamaMLP):
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def __init__(self, config):
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super().__init__(config)
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self.gate_proj = nn.Linear(self.hidden_size, self.intermediate_size, bias=False)
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self.up_proj = nn.Linear(self.hidden_size, self.intermediate_size, bias=False)
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self.down_proj = nn.Linear(self.intermediate_size, self.hidden_size, bias=False)
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class CohereAttention(LlamaAttention):
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"""Multi-headed attention from 'Attention Is All You Need' paper"""
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def __init__(self, config: CohereConfig, layer_idx: Optional[int] = None):
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super().__init__(config, layer_idx)
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self.use_qk_norm = config.use_qk_norm
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if self.use_qk_norm:
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# When sharding the model using Tensor Parallelism, need to be careful to use n_local_heads
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self.q_norm = CohereLayerNorm(
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hidden_size=(config.num_attention_heads, self.head_dim), eps=config.layer_norm_eps
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)
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self.k_norm = CohereLayerNorm(
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hidden_size=(config.num_key_value_heads, self.head_dim), eps=config.layer_norm_eps
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)
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def forward(
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self,
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hidden_states: torch.Tensor,
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position_embeddings: tuple[torch.Tensor, torch.Tensor],
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attention_mask: Optional[torch.Tensor],
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past_key_value: Optional[Cache] = None,
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cache_position: Optional[torch.LongTensor] = None,
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**kwargs: Unpack[FlashAttentionKwargs],
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) -> tuple[torch.Tensor, Optional[torch.Tensor], Optional[tuple[torch.Tensor]]]:
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input_shape = hidden_states.shape[:-1]
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hidden_shape = (*input_shape, -1, self.head_dim)
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query_states = self.q_proj(hidden_states).view(hidden_shape)
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key_states = self.k_proj(hidden_states).view(hidden_shape)
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value_states = self.v_proj(hidden_states).view(hidden_shape)
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if self.use_qk_norm: # main diff from Llama
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query_states = self.q_norm(query_states)
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key_states = self.k_norm(key_states)
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query_states = query_states.transpose(1, 2)
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key_states = key_states.transpose(1, 2)
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value_states = value_states.transpose(1, 2)
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cos, sin = position_embeddings
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query_states, key_states = apply_rotary_pos_emb(query_states, key_states, cos, sin)
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if past_key_value is not None:
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# sin and cos are specific to RoPE models; position_ids needed for the static cache
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cache_kwargs = {"sin": sin, "cos": cos, "cache_position": cache_position}
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key_states, value_states = past_key_value.update(key_states, value_states, self.layer_idx, cache_kwargs)
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attention_interface: Callable = eager_attention_forward
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if self.config._attn_implementation != "eager":
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attention_interface = ALL_ATTENTION_FUNCTIONS[self.config._attn_implementation]
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attn_output, attn_weights = attention_interface(
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self,
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query_states,
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key_states,
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value_states,
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attention_mask,
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dropout=0.0 if not self.training else self.attention_dropout,
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scaling=self.scaling,
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**kwargs,
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)
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attn_output = attn_output.reshape(*input_shape, -1).contiguous()
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attn_output = self.o_proj(attn_output)
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return attn_output, attn_weights
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class CohereDecoderLayer(GradientCheckpointingLayer):
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def __init__(self, config: CohereConfig, layer_idx: int):
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super().__init__()
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self.hidden_size = config.hidden_size
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self.self_attn = CohereAttention(config=config, layer_idx=layer_idx)
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self.mlp = CohereMLP(config)
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self.input_layernorm = CohereLayerNorm(hidden_size=(config.hidden_size), eps=config.layer_norm_eps)
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def forward(
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self,
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hidden_states: torch.Tensor,
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attention_mask: Optional[torch.Tensor] = None,
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position_ids: Optional[torch.LongTensor] = None,
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past_key_value: Optional[Cache] = None,
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use_cache: Optional[bool] = False,
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cache_position: Optional[torch.LongTensor] = None,
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position_embeddings: Optional[tuple[torch.Tensor, torch.Tensor]] = None, # necessary, but kept here for BC
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**kwargs: Unpack[FlashAttentionKwargs],
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) -> tuple[torch.FloatTensor, Optional[tuple[torch.FloatTensor, torch.FloatTensor]]]:
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"""
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Args:
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hidden_states (`torch.FloatTensor`): input to the layer of shape `(batch, seq_len, embed_dim)`
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attention_mask (`torch.FloatTensor`, *optional*):
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attention mask of size `(batch_size, sequence_length)` if flash attention is used or `(batch_size, 1,
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query_sequence_length, key_sequence_length)` if default attention is used.
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past_key_value (`Tuple(torch.FloatTensor)`, *optional*): cached past key and value projection states
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output_attentions (`bool`, *optional*):
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Whether or not to return the attentions tensors of all attention layers. See `attentions` under
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returned tensors for more detail.
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use_cache (`bool`, *optional*):
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If set to `True`, `past_key_values` key value states are returned and can be used to speed up decoding
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(see `past_key_values`).
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cache_position (`torch.LongTensor` of shape `(sequence_length)`, *optional*):
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Indices depicting the position of the input sequence tokens in the sequence
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position_embeddings (`tuple[torch.FloatTensor, torch.FloatTensor]`, *optional*):
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Tuple containing the cosine and sine positional embeddings of shape `(batch_size, seq_len, head_dim)`,
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with `head_dim` being the embedding dimension of each attention head.
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"""
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residual = hidden_states
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hidden_states = self.input_layernorm(hidden_states)
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hidden_states_attention, _ = self.self_attn(
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hidden_states=hidden_states,
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attention_mask=attention_mask,
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position_ids=position_ids,
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past_key_value=past_key_value,
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use_cache=use_cache,
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cache_position=cache_position,
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position_embeddings=position_embeddings,
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**kwargs,
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)
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hidden_states_mlp = self.mlp(hidden_states)
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hidden_states = residual + hidden_states_attention + hidden_states_mlp
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return hidden_states
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class CohereModel(LlamaModel):
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def __init__(self, config: CohereConfig):
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super().__init__(config)
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self.layers = nn.ModuleList(
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[CohereDecoderLayer(config, layer_idx) for layer_idx in range(config.num_hidden_layers)]
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)
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self.rotary_emb = CohereRotaryEmbedding(config=config)
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self.norm = CohereLayerNorm(hidden_size=(config.hidden_size), eps=config.layer_norm_eps)
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class CohereForCausalLM(LlamaForCausalLM):
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def __init__(self, config):
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super().__init__(config)
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self.model = CohereModel(config)
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self.logit_scale = config.logit_scale
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self.tie_word_embeddings = config.tie_word_embeddings
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def forward(
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self,
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input_ids: Optional[torch.LongTensor] = None,
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attention_mask: Optional[torch.Tensor] = None,
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position_ids: Optional[torch.LongTensor] = None,
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past_key_values: Optional[Union[Cache, list[torch.FloatTensor]]] = None,
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inputs_embeds: Optional[torch.FloatTensor] = None,
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labels: Optional[torch.LongTensor] = None,
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use_cache: Optional[bool] = None,
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output_attentions: Optional[bool] = None,
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output_hidden_states: Optional[bool] = None,
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cache_position: Optional[torch.LongTensor] = None,
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logits_to_keep: Union[int, torch.Tensor] = 0,
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**kwargs: Unpack[TransformersKwargs],
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) -> CausalLMOutputWithPast:
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r"""
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labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
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Labels for computing the masked language modeling loss. Indices should either be in `[0, ...,
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config.vocab_size]` or -100 (see `input_ids` docstring). Tokens with indices set to `-100` are ignored
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(masked), the loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]`.
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Example:
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```python
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>> from transformers import AutoTokenizer, CohereForCausalLM
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>> model = CohereForCausalLM.from_pretrained("CohereForAI/c4ai-command-r-v01")
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>> tokenizer = AutoTokenizer.from_pretrained("CohereForAI/c4ai-command-r-v01")
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>> prompt = "Hey, are you conscious? Can you talk to me?"
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>> inputs = tokenizer(prompt, return_tensors="pt")
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>> # Generate
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>> generate_ids = model.generate(inputs.input_ids, max_length=30)
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>> tokenizer.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
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"Hey, are you conscious? Can you talk to me?\nI'm not conscious, but I can talk to you."
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```"""
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output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
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output_hidden_states = (
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output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
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)
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# decoder outputs consists of (dec_features, layer_state, dec_hidden, dec_attn)
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outputs: BaseModelOutputWithPast = self.model(
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input_ids=input_ids,
|
||
|
|
attention_mask=attention_mask,
|
||
|
|
position_ids=position_ids,
|
||
|
|
past_key_values=past_key_values,
|
||
|
|
inputs_embeds=inputs_embeds,
|
||
|
|
use_cache=use_cache,
|
||
|
|
output_attentions=output_attentions,
|
||
|
|
output_hidden_states=output_hidden_states,
|
||
|
|
cache_position=cache_position,
|
||
|
|
**kwargs,
|
||
|
|
)
|
||
|
|
|
||
|
|
hidden_states = outputs.last_hidden_state
|
||
|
|
# Only compute necessary logits, and do not upcast them to float if we are not computing the loss
|
||
|
|
slice_indices = slice(-logits_to_keep, None) if isinstance(logits_to_keep, int) else logits_to_keep
|
||
|
|
logits = self.lm_head(hidden_states[:, slice_indices, :])
|
||
|
|
logits = logits * self.logit_scale # main diff from Llama
|
||
|
|
|
||
|
|
loss = None
|
||
|
|
if labels is not None:
|
||
|
|
loss = self.loss_function(logits=logits, labels=labels, vocab_size=self.config.vocab_size, **kwargs)
|
||
|
|
|
||
|
|
return CausalLMOutputWithPast(
|
||
|
|
loss=loss,
|
||
|
|
logits=logits,
|
||
|
|
past_key_values=outputs.past_key_values,
|
||
|
|
hidden_states=outputs.hidden_states,
|
||
|
|
attentions=outputs.attentions,
|
||
|
|
)
|
||
|
|
|
||
|
|
|
||
|
|
__all__ = [
|
||
|
|
"CohereForCausalLM",
|
||
|
|
"CohereModel",
|
||
|
|
"CoherePreTrainedModel", # noqa: F822
|
||
|
|
]
|