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modeling_gpt_bigcode.py
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modeling_gpt_bigcode.py
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# coding=utf-8
# Copyright 2023 The Bigcode team and HuggingFace Inc. team.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""PyTorch GPTBigCode model."""
import math
from typing import List, Optional, Tuple, Union
import torch
import torch.nn.functional as F
import torch.utils.checkpoint
from torch import nn
from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss, MSELoss
from ...activations import ACT2FN
from ...modeling_attn_mask_utils import AttentionMaskConverter
from ...modeling_outputs import (
BaseModelOutputWithPastAndCrossAttentions,
CausalLMOutputWithCrossAttentions,
SequenceClassifierOutputWithPast,
TokenClassifierOutput,
)
from ...modeling_utils import PreTrainedModel
from ...pytorch_utils import is_torch_greater_or_equal_than_2_2
from ...utils import (
add_code_sample_docstrings,
add_start_docstrings,
add_start_docstrings_to_model_forward,
is_flash_attn_2_available,
is_flash_attn_greater_or_equal_2_10,
logging,
)
from .configuration_gpt_bigcode import GPTBigCodeConfig
if is_flash_attn_2_available():
from flash_attn import flash_attn_func, flash_attn_varlen_func
from flash_attn.bert_padding import index_first_axis, pad_input, unpad_input # noqa
logger = logging.get_logger(__name__)
_CHECKPOINT_FOR_DOC = "bigcode/gpt_bigcode-santacoder"
_CONFIG_FOR_DOC = "GPTBigCodeConfig"
# Fused kernels
# Use separate functions for each case because conditionals prevent kernel fusion.
# TODO: Could have better fused kernels depending on scaling, dropout and head mask.
# Is it doable without writing 32 functions?
@torch.jit.script
def upcast_masked_softmax(
x: torch.Tensor, mask: torch.Tensor, mask_value: torch.Tensor, scale: float, softmax_dtype: torch.dtype
):
input_dtype = x.dtype
x = x.to(softmax_dtype) * scale
x = torch.where(mask, x, mask_value)
x = torch.nn.functional.softmax(x, dim=-1).to(input_dtype)
return x
@torch.jit.script
def upcast_softmax(x: torch.Tensor, scale: float, softmax_dtype: torch.dtype):
input_dtype = x.dtype
x = x.to(softmax_dtype) * scale
x = torch.nn.functional.softmax(x, dim=-1).to(input_dtype)
return x
@torch.jit.script
def masked_softmax(x: torch.Tensor, mask: torch.Tensor, mask_value: torch.Tensor):
x = torch.where(mask, x, mask_value)
x = torch.nn.functional.softmax(x, dim=-1)
return x
# Copied from transformers.models.llama.modeling_llama._get_unpad_data
def _get_unpad_data(attention_mask):
seqlens_in_batch = attention_mask.sum(dim=-1, dtype=torch.int32)
indices = torch.nonzero(attention_mask.flatten(), as_tuple=False).flatten()
max_seqlen_in_batch = seqlens_in_batch.max().item()
cu_seqlens = F.pad(torch.cumsum(seqlens_in_batch, dim=0, dtype=torch.int32), (1, 0))
return (
indices,
cu_seqlens,
max_seqlen_in_batch,
)
class GPTBigCodeAttention(nn.Module):
def __init__(self, config, is_cross_attention=False, layer_idx=None):
super().__init__()
self.config = config
self.mask_value = None
self.multi_query = config.multi_query
self.embed_dim = config.hidden_size
self.num_heads = config.num_attention_heads
self.head_dim = self.embed_dim // self.num_heads
self.kv_heads = 1 if self.multi_query else self.num_heads
self.kv_dim = self.kv_heads * self.head_dim
self.split_size = self.embed_dim
self.is_causal = True
if self.head_dim * self.num_heads != self.embed_dim:
raise ValueError(
f"`embed_dim` must be divisible by num_heads (got `embed_dim`: {self.embed_dim} and `num_heads`:"
f" {self.num_heads})."
)
self.scale_attn_weights = config.scale_attn_weights
self.is_cross_attention = is_cross_attention
self.layer_idx = layer_idx
self.attention_softmax_in_fp32 = config.attention_softmax_in_fp32
self.scale_attention_softmax_in_fp32 = (
config.scale_attention_softmax_in_fp32 and config.attention_softmax_in_fp32
)
self.attn_pdrop = config.attn_pdrop
if self.is_cross_attention:
if self.multi_query:
raise NotImplementedError("Multi-Query Attention not supported for cross_attention")
self.c_attn = nn.Linear(self.embed_dim, 2 * self.embed_dim)
self.q_attn = nn.Linear(self.embed_dim, self.embed_dim)
else:
self.c_attn = nn.Linear(self.embed_dim, self.embed_dim + 2 * self.kv_dim)
self.c_proj = nn.Linear(self.embed_dim, self.embed_dim)
self.attn_dropout = nn.Dropout(config.attn_pdrop)
self.resid_dropout = nn.Dropout(config.resid_pdrop)
def _get_mask_value(self, device, dtype):
# torch.where expects a tensor. We use a cache to avoid recreating it every time.
if self.mask_value is None or self.mask_value.dtype != dtype or self.mask_value.device != device:
self.mask_value = torch.full([], torch.finfo(dtype).min, dtype=dtype, device=device)
return self.mask_value
def _attn(self, query, key, value, attention_mask=None, head_mask=None):
dtype = query.dtype
softmax_dtype = torch.float32 if self.attention_softmax_in_fp32 else dtype
upcast = dtype != softmax_dtype
unscale = self.layer_idx + 1 if self.scale_attention_softmax_in_fp32 and upcast else 1
scale_factor = unscale**-1
if self.scale_attn_weights:
scale_factor /= self.head_dim**0.5
# MQA models: (batch_size, query_length, num_heads * head_dim)
# MHA models: (batch_size, num_heads, query_length, head_dim)
query_shape = query.shape
batch_size = query_shape[0]
key_length = key.size(-1)
if self.multi_query:
# (batch_size, query_length, num_heads, head_dim) x (batch_size, head_dim, key_length)
# -> (batch_size, query_length, num_heads, key_length)
query_length = query_shape[1]
attn_shape = (batch_size, query_length, self.num_heads, key_length)
attn_view = (batch_size, query_length * self.num_heads, key_length)
# No copy needed for MQA 2, or when layer_past is provided.
query = query.reshape(batch_size, query_length * self.num_heads, self.head_dim)
else:
# (batch_size, num_heads, query_length, head_dim) x (batch_size, num_heads, head_dim, key_length)
# -> (batch_size, num_heads, query_length, key_length)
query_length = query_shape[2]
attn_shape = (batch_size, self.num_heads, query_length, key_length)
attn_view = (batch_size * self.num_heads, query_length, key_length)
# Always copies
query = query.reshape(batch_size * self.num_heads, query_length, self.head_dim)
# No copy when layer_past is provided.
key = key.reshape(batch_size * self.num_heads, self.head_dim, key_length)
attn_weights = torch.empty(attn_view, device=query.device, dtype=query.dtype)
if query.device.type == "cpu":
# This is needed because of a bug in pytorch https://github.com/pytorch/pytorch/issues/80588.
# The bug was fixed in https://github.com/pytorch/pytorch/pull/96086,
# but the fix has not been released as of pytorch version 2.0.0.
attn_weights = torch.zeros_like(attn_weights)
beta = 1
else:
beta = 0
attn_weights = torch.baddbmm(attn_weights, query, key, beta=beta, alpha=scale_factor).view(attn_shape)
if upcast:
# Use a fused kernel to prevent a large overhead from casting and scaling.
# Sub-optimal when the key length is not a multiple of 8.
if attention_mask is None:
attn_weights = upcast_softmax(attn_weights, unscale, softmax_dtype)
else:
mask_value = self._get_mask_value(attn_weights.device, softmax_dtype)
attn_weights = upcast_masked_softmax(attn_weights, attention_mask, mask_value, unscale, softmax_dtype)
else:
if attention_mask is not None:
mask_value = self._get_mask_value(attn_weights.device, softmax_dtype)
# The fused kernel is very slow when the key length is not a multiple of 8, so we skip fusion.
attn_weights = torch.where(attention_mask, attn_weights, mask_value)
attn_weights = torch.nn.functional.softmax(attn_weights, dim=-1)
attn_weights = self.attn_dropout(attn_weights)
# Mask heads if we want to
if head_mask is not None:
if self.multi_query:
head_mask = head_mask.transpose(1, 2)
attn_weights = attn_weights * head_mask
if self.multi_query:
attn_output = torch.bmm(attn_weights.view(attn_view), value).view(query_shape)
else:
attn_output = torch.matmul(attn_weights, value)
return attn_output, attn_weights
def forward(
self,
hidden_states: torch.Tensor,
layer_past: Optional[torch.Tensor] = None,
attention_mask: Optional[torch.Tensor] = None,
head_mask: Optional[torch.Tensor] = None,
encoder_hidden_states: Optional[torch.Tensor] = None,
encoder_attention_mask: Optional[torch.Tensor] = None,
use_cache: Optional[bool] = False,
output_attentions: Optional[bool] = False,
) -> Union[
Tuple[torch.Tensor, Optional[torch.Tensor]],
Tuple[torch.Tensor, Optional[torch.Tensor], Tuple[torch.Tensor, ...]],
]:
if encoder_hidden_states is not None:
if not hasattr(self, "q_attn") or not self.is_cross_attention:
raise ValueError(
"If class is used as cross attention, the weights `q_attn` have to be defined. "
"Please make sure to instantiate class with `GPTBigCodeAttention(..., is_cross_attention=True)`."
)
query = self.q_attn(hidden_states)
key_value = self.c_attn(encoder_hidden_states)
attention_mask = encoder_attention_mask
elif self.multi_query:
query, key_value = self.c_attn(hidden_states).split((self.embed_dim, 2 * self.kv_dim), dim=2)
else:
# Note: We split as (self.num_heads, 3, self.head_dim) instead of (3, self.num_heads, self.head_dim),
# i.e., the memory layout is not the same as GPT2.
# This makes the concatenation with past_key_value more efficient.
query, key_value = (
self.c_attn(hidden_states)
.view(*hidden_states.shape[:2], self.num_heads, 3 * self.head_dim)
.transpose(1, 2)
.split((self.head_dim, 2 * self.head_dim), dim=3)
)
if layer_past is not None:
key_value = torch.cat((layer_past, key_value), dim=-2)
present = key_value if use_cache else None
key, value = key_value.split((self.head_dim, self.head_dim), dim=-1)
attn_output, attn_weights = self._attn(query, key.transpose(-1, -2), value, attention_mask, head_mask)
if not self.multi_query:
attn_output = attn_output.transpose(1, 2).reshape(hidden_states.shape)
attn_output = self.c_proj(attn_output)
attn_output = self.resid_dropout(attn_output)
outputs = (attn_output, present)
if output_attentions:
if self.multi_query:
# Transpose to return weights in the usual format (batch_size, num_heads, query_length, key_length)
attn_weights = attn_weights.transpose(1, 2)
outputs += (attn_weights,)
return outputs # a, present, (attentions)
class GPTBigCodeFlashAttention2(GPTBigCodeAttention):
"""
GPTBigCode flash attention module. This module inherits from `GPTBigCodeAttention` as the weights of the module
stays untouched. The only required change would be on the forward pass where it needs to correctly call the public
API of flash attention and deal with padding tokens in case the input contains any of them.
"""
# Copied from transformers.models.llama.modeling_llama.LlamaFlashAttention2.__init__
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
# TODO: Should be removed once Flash Attention for RoCm is bumped to 2.1.
# flash_attn<2.1 generates top-left aligned causal mask, while what is needed here is bottom-right alignement, that was made default for flash_attn>=2.1. This attribute is used to handle this difference. Reference: https://github.com/Dao-AILab/flash-attention/releases/tag/v2.1.0.
# Beware that with flash_attn<2.1, using q_seqlen != k_seqlen (except for the case q_seqlen == 1) produces a wrong mask (top-left).
self._flash_attn_uses_top_left_mask = not is_flash_attn_greater_or_equal_2_10()
def forward(
self,
hidden_states: torch.Tensor,
layer_past: Optional[torch.Tensor] = None,
attention_mask: Optional[torch.Tensor] = None,
head_mask: Optional[torch.Tensor] = None,
encoder_hidden_states: Optional[torch.Tensor] = None,
encoder_attention_mask: Optional[torch.Tensor] = None,
use_cache: Optional[bool] = False,
output_attentions: Optional[bool] = False,
) -> Union[
Tuple[torch.Tensor, Optional[torch.Tensor]],
Tuple[torch.Tensor, Optional[torch.Tensor], Tuple[torch.Tensor, ...]],
]:
if encoder_hidden_states is not None:
if not hasattr(self, "q_attn") or not self.is_cross_attention:
raise ValueError(
"If class is used as cross attention, the weights `q_attn` have to be defined. "
"Please make sure to instantiate class with `GPTBigCodeAttention(..., is_cross_attention=True)`."
)
query = self.q_attn(hidden_states)
key_value = self.c_attn(encoder_hidden_states)
attention_mask = encoder_attention_mask
elif self.multi_query:
query, key_value = self.c_attn(hidden_states).split((self.embed_dim, 2 * self.kv_dim), dim=2)
else:
# Note: We split as (self.num_heads, 3, self.head_dim) instead of (3, self.num_heads, self.head_dim),
# i.e., the memory layout is not the same as GPT2.
# This makes the concatenation with past_key_value more efficient.
query, key_value = (
self.c_attn(hidden_states)
.view(*hidden_states.shape[:2], self.num_heads, 3 * self.head_dim)
.transpose(1, 2)
.split((self.head_dim, 2 * self.head_dim), dim=3)
)
if layer_past is not None:
key_value = torch.cat((layer_past, key_value), dim=-2)
present = key_value if use_cache else None
key, value = key_value.split((self.head_dim, self.head_dim), dim=-1)
# Flash attention requires the input to have the shape
# batch_size x seq_length x head_dim x hidden_dim
if self.multi_query:
batch_size, query_length, _ = query.shape
query = query.reshape(batch_size, query_length, self.num_heads, self.head_dim)
key = key.unsqueeze(2)
value = value.unsqueeze(2)
else:
query_length = query.shape[2]
batch_size, _, tgt, _ = key.shape
query = query.transpose(1, 2).reshape(batch_size, query_length, self.num_heads, self.head_dim)
key = key.transpose(1, 2).reshape(batch_size, tgt, self.num_heads, self.head_dim)
value = value.transpose(1, 2).reshape(batch_size, tgt, self.num_heads, self.head_dim)
attn_dropout = self.attn_pdrop if self.training else 0.0
# In PEFT, usually we cast the layer norms in float32 for training stability reasons
# therefore the input hidden states gets silently casted in float32. Hence, we need
# cast them back in float16 just to be sure everything works as expected.
input_dtype = query.dtype
if input_dtype == torch.float32:
if torch.is_autocast_enabled():
target_dtype = torch.get_autocast_gpu_dtype()
# Handle the case where the model is quantized
elif hasattr(self.config, "_pre_quantization_dtype"):
target_dtype = self.config._pre_quantization_dtype
else:
target_dtype = self.c_attn.weight.dtype
logger.warning_once(
f"The input hidden states seems to be silently casted in float32, this might be related to"
f" the fact you have upcasted embedding or layer norm layers in float32. We will cast back the input in"
f" {target_dtype}."
)
query = query.to(target_dtype)
key = key.to(target_dtype)
value = value.to(target_dtype)
attn_output = self._flash_attention_forward(
query, key, value, attention_mask, query_length, dropout=attn_dropout
)
attn_weights_reshaped = attn_output.reshape(batch_size, query_length, self.num_heads * self.head_dim)
attn_output = self.c_proj(attn_weights_reshaped)
attn_output = self.resid_dropout(attn_output)
outputs = (attn_output, present)
if output_attentions:
if self.multi_query:
# Transpose to return weights in the usual format (batch_size, num_heads, query_length, key_length)
attn_weights_reshaped = attn_weights_reshaped.transpose(1, 2)
else:
attn_weights_reshaped = None
outputs += (attn_weights_reshaped,)
return outputs # a, present, (attentions)
# Copied from transformers.models.llama.modeling_llama.LlamaFlashAttention2._flash_attention_forward
def _flash_attention_forward(
self, query_states, key_states, value_states, attention_mask, query_length, dropout=0.0, softmax_scale=None
):
"""
Calls the forward method of Flash Attention - if the input hidden states contain at least one padding token
first unpad the input, then computes the attention scores and pad the final attention scores.
Args:
query_states (`torch.Tensor`):
Input query states to be passed to Flash Attention API
key_states (`torch.Tensor`):
Input key states to be passed to Flash Attention API
value_states (`torch.Tensor`):
Input value states to be passed to Flash Attention API
attention_mask (`torch.Tensor`):
The padding mask - corresponds to a tensor of size `(batch_size, seq_len)` where 0 stands for the
position of padding tokens and 1 for the position of non-padding tokens.
dropout (`float`):
Attention dropout
softmax_scale (`float`, *optional*):
The scaling of QK^T before applying softmax. Default to 1 / sqrt(head_dim)
"""
if not self._flash_attn_uses_top_left_mask:
causal = self.is_causal
else:
# TODO: Remove the `query_length != 1` check once Flash Attention for RoCm is bumped to 2.1. For details, please see the comment in LlamaFlashAttention2 __init__.
causal = self.is_causal and query_length != 1
# Contains at least one padding token in the sequence
if attention_mask is not None:
batch_size = query_states.shape[0]
query_states, key_states, value_states, indices_q, cu_seq_lens, max_seq_lens = self._upad_input(
query_states, key_states, value_states, attention_mask, query_length
)
cu_seqlens_q, cu_seqlens_k = cu_seq_lens
max_seqlen_in_batch_q, max_seqlen_in_batch_k = max_seq_lens
attn_output_unpad = flash_attn_varlen_func(
query_states,
key_states,
value_states,
cu_seqlens_q=cu_seqlens_q,
cu_seqlens_k=cu_seqlens_k,
max_seqlen_q=max_seqlen_in_batch_q,
max_seqlen_k=max_seqlen_in_batch_k,
dropout_p=dropout,
softmax_scale=softmax_scale,
causal=causal,
)
attn_output = pad_input(attn_output_unpad, indices_q, batch_size, query_length)
else:
attn_output = flash_attn_func(
query_states, key_states, value_states, dropout, softmax_scale=softmax_scale, causal=causal
)
return attn_output
# Copied from transformers.models.llama.modeling_llama.LlamaFlashAttention2._upad_input
def _upad_input(self, query_layer, key_layer, value_layer, attention_mask, query_length):
indices_k, cu_seqlens_k, max_seqlen_in_batch_k = _get_unpad_data(attention_mask)
batch_size, kv_seq_len, num_key_value_heads, head_dim = key_layer.shape
key_layer = index_first_axis(
key_layer.reshape(batch_size * kv_seq_len, num_key_value_heads, head_dim), indices_k
)
value_layer = index_first_axis(
value_layer.reshape(batch_size * kv_seq_len, num_key_value_heads, head_dim), indices_k
)
if query_length == kv_seq_len:
query_layer = index_first_axis(
query_layer.reshape(batch_size * kv_seq_len, self.num_heads, head_dim), indices_k
)
cu_seqlens_q = cu_seqlens_k
max_seqlen_in_batch_q = max_seqlen_in_batch_k
indices_q = indices_k
elif query_length == 1:
max_seqlen_in_batch_q = 1
cu_seqlens_q = torch.arange(
batch_size + 1, dtype=torch.int32, device=query_layer.device
) # There is a memcpy here, that is very bad.
indices_q = cu_seqlens_q[:-1]
query_layer = query_layer.squeeze(1)
else:
# The -q_len: slice assumes left padding.
attention_mask = attention_mask[:, -query_length:]
query_layer, indices_q, cu_seqlens_q, max_seqlen_in_batch_q = unpad_input(query_layer, attention_mask)
return (
query_layer,
key_layer,
value_layer,
indices_q,
(cu_seqlens_q, cu_seqlens_k),
(max_seqlen_in_batch_q, max_seqlen_in_batch_k),
)
class GPTBigCodeSdpaAttention(GPTBigCodeAttention):
def _attn(self, query, key, value, attention_mask=None, head_mask=None):
if head_mask is not None:
# The super dispatch is done in the forward.
raise ValueError(
"PyTorch SDPA does not support head_mask. Please open an issue in Transformers repository."
)
scale = None
if not self.scale_attn_weights:
scale = 1
# MQA models: (batch_size, query_length, num_heads * head_dim)
# MHA models: (batch_size, num_heads, query_length, head_dim)
query_shape = query.shape
batch_size = query_shape[0]
key.shape[-2]
if self.multi_query:
query_length = query_shape[1]
# SDPA requires the dimension [..., sequence_length, head_dim].
query = query.view(batch_size, query_length, self.num_heads, self.head_dim).transpose(1, 2)
# Without these unsqueeze, SDPA complains as the query and key/value have a different number of dimensions.
key = key.unsqueeze(1)
value = value.unsqueeze(1)
# Although these expand are not numerically useful, PyTorch can not dispatch to memory-efficient backend
# and flash attention backend (No available kernel. Aborting execution.) from the shapes
# query = [batch_size, num_heads, query_length, head_dim]
# key = [batch_size, 1, past_length, head_dim]
# value = [batch_size, 1, past_length, head_dim]
#
# torch==2.1.2 is bugged with non-contiguous inputs with custom attn_mask (https://github.com/pytorch/pytorch/issues/112577), hence the check.
if is_torch_greater_or_equal_than_2_2:
key = key.expand(-1, self.num_heads, -1, -1)
value = value.expand(-1, self.num_heads, -1, -1)
else:
query_length = query_shape[-1]
# See the comment above.
if query.device.type == "cuda" and attention_mask is not None:
query = query.contiguous()
key = key.contiguous()
value = value.contiguous()
sdpa_result = torch.nn.functional.scaled_dot_product_attention(
query,
key,
value,
attn_mask=attention_mask,
dropout_p=self.attn_pdrop if self.training else 0.0,
# The query_length > 1 is necessary to match with AttentionMaskConverter.to_causal_4d that does not create a causal mask in case query_length == 1.
is_causal=self.is_causal and attention_mask is None and query_length > 1,
scale=scale,
)
if self.multi_query:
# (batch_size, num_heads, seq_len, head_dim) --> (batch_size, seq_len, num_heads, head_dim)
sdpa_result = sdpa_result.transpose(1, 2)
# Reshape is kind of expensive here, as it does a memory copy,
# but I did not manage to make away without it (logits do not match when using view)
# (batch_size, seq_len, num_heads, head_dim) --> (batch_size, seq_len, num_heads * head_dim)
sdpa_result = sdpa_result.reshape(query_shape)
return sdpa_result, None
def forward(
self,
hidden_states: torch.Tensor,
layer_past: Optional[torch.Tensor] = None,
attention_mask: Optional[torch.Tensor] = None,
head_mask: Optional[torch.Tensor] = None,
encoder_hidden_states: Optional[torch.Tensor] = None,
encoder_attention_mask: Optional[torch.Tensor] = None,
use_cache: Optional[bool] = False,
output_attentions: Optional[bool] = False,
) -> Union[
Tuple[torch.Tensor, Optional[torch.Tensor]],
Tuple[torch.Tensor, Optional[torch.Tensor], Tuple[torch.Tensor, ...]],
]:
if encoder_hidden_states is not None:
if not hasattr(self, "q_attn") or not self.is_cross_attention:
raise ValueError(
"If class is used as cross attention, the weights `q_attn` have to be defined. "
"Please make sure to instantiate class with `GPTBigCodeAttention(..., is_cross_attention=True)`."
)
query = self.q_attn(hidden_states)
key_value = self.c_attn(encoder_hidden_states)
attention_mask = encoder_attention_mask
elif self.multi_query:
query, key_value = self.c_attn(hidden_states).split((self.embed_dim, 2 * self.kv_dim), dim=2)
else:
# Note: We split as (self.num_heads, 3, self.head_dim) instead of (3, self.num_heads, self.head_dim),
# i.e., the memory layout is not the same as GPT2.
# This makes the concatenation with past_key_value more efficient.
query, key_value = (
self.c_attn(hidden_states)
.view(*hidden_states.shape[:2], self.num_heads, 3 * self.head_dim)
.transpose(1, 2)
.split((self.head_dim, 2 * self.head_dim), dim=3)
)
if layer_past is not None:
key_value = torch.cat((layer_past, key_value), dim=-2)
present = key_value if use_cache else None
key, value = key_value.split((self.head_dim, self.head_dim), dim=-1)
if not output_attentions and head_mask is None:
# Difference with the original implementation: there is no need to transpose the key here,
# as SDPA expects seq_length to be at index -2 for the key as well
attn_output, attn_weights = self._attn(query, key, value, attention_mask, head_mask)
else:
# TODO: Improve this warning with e.g. `model.config._attn_implementation = "manual"` once this is implemented.
logger.warning_once(
"GPTBigCodeModel is using GPTBigCodeSdpaAttention, but `torch.nn.functional.scaled_dot_product_attention` does not support `output_attentions=True` and `head_mask` not None."
' Falling back to the manual attention implementation, but specifying the manual implementation will be required from Transformers version v5.0.0 onwards. This warning can be removed using the argument `attn_implementation="eager"` when loading the model.'
)
attn_output, attn_weights = super()._attn(query, key.transpose(-1, -2), value, attention_mask, head_mask)
if not self.multi_query:
attn_output = attn_output.transpose(1, 2).reshape(hidden_states.shape)
attn_output = self.c_proj(attn_output)
attn_output = self.resid_dropout(attn_output)
outputs = (attn_output, present)
if output_attentions:
if self.multi_query:
# Transpose to return weights in the usual format (batch_size, num_heads, query_length, key_length)
attn_weights = attn_weights.transpose(1, 2)
outputs += (attn_weights,)
return outputs
class GPTBigCodeMLP(nn.Module):
def __init__(self, intermediate_size, config):
super().__init__()
embed_dim = config.hidden_size
self.c_fc = nn.Linear(embed_dim, intermediate_size)
self.c_proj = nn.Linear(intermediate_size, embed_dim)
self.act = ACT2FN[config.activation_function]
self.dropout = nn.Dropout(config.resid_pdrop)
# Copied from transformers.models.gpt2.modeling_gpt2.GPT2MLP.forward
def forward(self, hidden_states: Optional[Tuple[torch.FloatTensor]]) -> torch.FloatTensor:
hidden_states = self.c_fc(hidden_states)
hidden_states = self.act(hidden_states)
hidden_states = self.c_proj(hidden_states)
hidden_states = self.dropout(hidden_states)
return hidden_states
GPTBIGCODE_ATTENTION_CLASSES = {
"eager": GPTBigCodeAttention,
"flash_attention_2": GPTBigCodeFlashAttention2,
"sdpa": GPTBigCodeSdpaAttention,
}
class GPTBigCodeBlock(nn.Module):
def __init__(self, config, layer_idx=None):
super().__init__()
hidden_size = config.hidden_size
self.inner_dim = config.n_inner if config.n_inner is not None else 4 * hidden_size
self.ln_1 = nn.LayerNorm(hidden_size, eps=config.layer_norm_epsilon)
self.attn = GPTBIGCODE_ATTENTION_CLASSES[config._attn_implementation](config, layer_idx=layer_idx)
self.ln_2 = nn.LayerNorm(hidden_size, eps=config.layer_norm_epsilon)
if config.add_cross_attention:
if config.multi_query:
raise NotImplementedError("Cross-attention not implemented for MQA")
self.crossattention = GPTBIGCODE_ATTENTION_CLASSES[config._attn_implementation](
config, is_cross_attention=True, layer_idx=layer_idx
)
self.ln_cross_attn = nn.LayerNorm(hidden_size, eps=config.layer_norm_epsilon)
self.mlp = GPTBigCodeMLP(self.inner_dim, config)
def forward(
self,
hidden_states: Optional[Tuple[torch.Tensor]],
layer_past: Optional[torch.Tensor] = None,
attention_mask: Optional[torch.Tensor] = None,
head_mask: Optional[torch.Tensor] = None,
encoder_hidden_states: Optional[torch.Tensor] = None,
encoder_attention_mask: Optional[torch.Tensor] = None,
use_cache: Optional[bool] = False,
output_attentions: Optional[bool] = False,
) -> Union[
Tuple[torch.Tensor], Tuple[torch.Tensor, torch.Tensor], Tuple[torch.Tensor, torch.Tensor, torch.Tensor]
]:
residual = hidden_states
hidden_states = self.ln_1(hidden_states)
attn_outputs = self.attn(
hidden_states,
layer_past=layer_past,
attention_mask=attention_mask,
head_mask=head_mask,
use_cache=use_cache,
output_attentions=output_attentions,
)
attn_output = attn_outputs[0] # output_attn: a, present, (attentions)
outputs = attn_outputs[1:]
# residual connection
hidden_states = attn_output + residual
if encoder_hidden_states is not None:
# add one self-attention block for cross-attention
if not hasattr(self, "crossattention"):
raise ValueError(
f"If `encoder_hidden_states` are passed, {self} has to be instantiated with "
"cross-attention layers by setting `config.add_cross_attention=True`"
)
residual = hidden_states
hidden_states = self.ln_cross_attn(hidden_states)
cross_attn_outputs = self.crossattention(
hidden_states,
attention_mask=attention_mask,
head_mask=head_mask,
encoder_hidden_states=encoder_hidden_states,
encoder_attention_mask=encoder_attention_mask,
output_attentions=output_attentions,
)
attn_output = cross_attn_outputs[0]
# residual connection
hidden_states = residual + attn_output
outputs = outputs + cross_attn_outputs[2:] # add cross attentions if we output attention weights
residual = hidden_states
hidden_states = self.ln_2(hidden_states)
feed_forward_hidden_states = self.mlp(hidden_states)
# residual connection
hidden_states = residual + feed_forward_hidden_states
if use_cache:
outputs = (hidden_states,) + outputs
else:
outputs = (hidden_states,) + outputs[1:]
return outputs # hidden_states, present, (attentions, cross_attentions)
class GPTBigCodePreTrainedModel(PreTrainedModel):
"""
An abstract class to handle weights initialization and a simple interface for downloading and loading pretrained
models.
"""
config_class = GPTBigCodeConfig
base_model_prefix = "transformer"
supports_gradient_checkpointing = True
_no_split_modules = ["GPTBigCodeBlock"]
_skip_keys_device_placement = "past_key_values"
_supports_flash_attn_2 = True
_supports_sdpa = True
def __init__(self, *inputs, **kwargs):
super().__init__(*inputs, **kwargs)
def _init_weights(self, module):
"""Initialize the weights."""
if isinstance(module, (GPTBigCodeMLP, GPTBigCodeAttention)):
# Reinitialize selected weights subject to the OpenAI GPT-2 Paper Scheme:
# > A modified initialization which accounts for the accumulation on the residual path with model depth. Scale
# > the weights of residual layers at initialization by a factor of 1/鈭歂 where N is the # of residual layers.
# > -- GPT-2 :: https://openai.com/blog/better-language-models/
#
# Reference (Megatron-LM): https://github.com/NVIDIA/Megatron-LM/blob/main/megatron/model/gpt_model.py
module.c_proj.weight.data.normal_(
mean=0.0, std=(self.config.initializer_range / math.sqrt(2 * self.config.n_layer))
)
module.c_proj._is_hf_initialized = True
elif isinstance(module, nn.Linear):
# Slightly different from the TF version which uses truncated_normal for initialization
# cf https://github.com/pytorch/pytorch/pull/5617
module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
if module.bias is not None:
module.bias.data.zero_()
elif isinstance(module, nn.Embedding):
module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
if module.padding_idx is not None:
module.weight.data[module.padding_idx].zero_()
elif isinstance(module, nn.LayerNorm):
module.bias.data.zero_()
module.weight.data.fill_(1.0)
GPT_BIGCODE_START_DOCSTRING = r"""
This model inherits from [`PreTrainedModel`]. Check the superclass documentation for the generic methods the
library implements for all its model (such as downloading or saving, resizing the input embeddings, pruning heads
etc.)
This model is also a PyTorch [torch.nn.Module](https://pytorch.org/docs/stable/nn.html#torch.nn.Module) subclass.
Use it as a regular PyTorch Module and refer to the PyTorch documentation for all matter related to general usage
and behavior.
Parameters:
config ([`GPTBigCodeConfig`]): Model configuration class with all the parameters of the model.
Initializing with a config file does not load the weights associated with the model, only the
configuration. Check out the [`~PreTrainedModel.from_pretrained`] method to load the model weights.
"""
GPT_BIGCODE_INPUTS_DOCSTRING = r"""
Args:
input_ids (`torch.Tensor` of shape `(batch_size, input_ids_length)`):
`input_ids_length` = `sequence_length` if `past_key_values` is `None` else
`past_key_values[0][0].shape[-2]` (`sequence_length` of input past key value states). Indices of input
sequence tokens in the vocabulary.
If `past_key_values` is used, only `input_ids` that do not have their past calculated should be passed as
`input_ids`.
Indices can be obtained using [`AutoTokenizer`]. See [`PreTrainedTokenizer.encode`] and
[`PreTrainedTokenizer.__call__`] for details.
[What are input IDs?](../glossary#input-ids)
past_key_values (`Tuple[torch.Tensor]` of length `config.n_layers`):
Contains precomputed hidden-states (key and values in the attention blocks) as computed by the model (see
`past_key_values` output below). Can be used to speed up sequential decoding. The `input_ids` which have
their past given to this model should not be passed as `input_ids` as they have already been computed.
attention_mask (`torch.Tensor` of shape `(batch_size, sequence_length)`, *optional*):
Mask to avoid performing attention on padding token indices. Mask values selected in `[0, 1]`:
- 1 for tokens that are **not masked**,
- 0 for tokens that are **masked**.
If `past_key_values` is used, `attention_mask` needs to contain the masking strategy that was used for
`past_key_values`. In other words, the `attention_mask` always has to have the length:
`len(past_key_values) + len(input_ids)`
[What are attention masks?](../glossary#attention-mask)
token_type_ids (`torch.Tensor` of shape `(batch_size, input_ids_length)`, *optional*):
Segment token indices to indicate first and second portions of the inputs. Indices are selected in `[0,
1]`:
- 0 corresponds to a *sentence A* token,
- 1 corresponds to a *sentence B* token.
[What are token type IDs?](../glossary#token-type-ids)
position_ids (`torch.Tensor` of shape `(batch_size, sequence_length)`, *optional*):
Indices of positions of each input sequence tokens in the position embeddings. Selected in the range `[0,
config.max_position_embeddings - 1]`.
[What are position IDs?](../glossary#position-ids)
head_mask (`torch.Tensor` of shape `(num_heads,)` or `(num_layers, num_heads)`, *optional*):
Mask to nullify selected heads of the self-attention modules. Mask values selected in `[0, 1]`:
- 1 indicates the head is **not masked**,
- 0 indicates the head is **masked**.
inputs_embeds (`torch.Tensor` of shape `(batch_size, sequence_length, hidden_size)`, *optional*):
Optionally, instead of passing `input_ids` you can choose to directly pass an embedded representation. This
is useful if you want more control over how to convert `input_ids` indices into associated vectors than the
model's internal embedding lookup matrix.
If `past_key_values` is used, optionally only the last `inputs_embeds` have to be input (see
`past_key_values`).
use_cache (`bool`, *optional*):
If set to `True`, `past_key_values` key value states are returned and can be used to speed up decoding (see
`past_key_values`).
output_attentions (`bool`, *optional*):
Whether or not to return the attentions tensors of all attention layers. See `attentions` under returned
tensors for more detail.
output_hidden_states (`bool`, *optional*):
Whether or not to return the hidden states of all layers. See `hidden_states` under returned tensors for
more detail.
return_dict (`bool`, *optional*):
Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
"""
@add_start_docstrings(
"The bare GPT_BIGCODE Model transformer outputting raw hidden-states without any specific head on top.",
GPT_BIGCODE_START_DOCSTRING,
)
class GPTBigCodeModel(GPTBigCodePreTrainedModel):
def __init__(self, config):
super().__init__(config)
self.multi_query = config.multi_query
self.embed_dim = config.hidden_size
self.wte = nn.Embedding(config.vocab_size, self.embed_dim)
self.wpe = nn.Embedding(config.max_position_embeddings, self.embed_dim)
self.drop = nn.Dropout(config.embd_pdrop)
self.h = nn.ModuleList([GPTBigCodeBlock(config, layer_idx=i) for i in range(config.num_hidden_layers)])
self.ln_f = nn.LayerNorm(self.embed_dim, eps=config.layer_norm_epsilon)
max_positions = config.max_position_embeddings
self.register_buffer(
"bias", torch.tril(torch.ones((max_positions, max_positions), dtype=torch.bool)), persistent=False
)
self.gradient_checkpointing = False
self._use_sdpa = config._attn_implementation == "sdpa"
self._use_flash_attention_2 = config._attn_implementation == "flash_attention_2"
# Initialize weights and apply final processing
self.post_init()
def get_input_embeddings(self):
return self.wte
def set_input_embeddings(self, new_embeddings):
self.wte = new_embeddings
@add_start_docstrings_to_model_forward(GPT_BIGCODE_INPUTS_DOCSTRING)
@add_code_sample_docstrings(
checkpoint=_CHECKPOINT_FOR_DOC,
output_type=BaseModelOutputWithPastAndCrossAttentions,
config_class=_CONFIG_FOR_DOC,
)
def forward(
self,
input_ids: Optional[torch.Tensor] = None,
past_key_values: Optional[List[torch.Tensor]] = None,
attention_mask: Optional[torch.Tensor] = None,
token_type_ids: Optional[torch.Tensor] = None,
position_ids: Optional[torch.Tensor] = None,
head_mask: Optional[torch.Tensor] = None,
inputs_embeds: Optional[torch.Tensor] = None,
encoder_hidden_states: Optional[torch.Tensor] = None,
encoder_attention_mask: Optional[torch.Tensor] = None,
use_cache: Optional[bool] = None,
output_attentions: Optional[bool] = None,
output_hidden_states: Optional[bool] = None,
return_dict: Optional[bool] = None,
) -> Union[Tuple, BaseModelOutputWithPastAndCrossAttentions]:
output_attentions = output_attentions if output_attentions is not None else self.config.output_attentions
output_hidden_states = (
output_hidden_states if output_hidden_states is not None else self.config.output_hidden_states
)
use_cache = use_cache if use_cache is not None else self.config.use_cache
return_dict = return_dict if return_dict is not None else self.config.use_return_dict
if input_ids is not None and inputs_embeds is not None:
raise ValueError("You cannot specify both input_ids and inputs_embeds at the same time")
elif input_ids is not None:
self.warn_if_padding_and_no_attention_mask(input_ids, attention_mask)
input_shape = input_ids.size()
input_ids = input_ids.view(-1, input_shape[-1])
batch_size = input_ids.shape[0]
elif inputs_embeds is not None:
input_shape = inputs_embeds.size()[:-1]
batch_size = inputs_embeds.shape[0]
else:
raise ValueError("You have to specify either input_ids or inputs_embeds")
if batch_size <= 0:
raise ValueError("batch_size has to be defined and > 0")
device = input_ids.device if input_ids is not None else inputs_embeds.device
if token_type_ids is not None:
token_type_ids = token_type_ids.view(-1, input_shape[-1])
if past_key_values is None:
past_length = 0
past_key_values = tuple([None] * len(self.h))
else:
past_length = past_key_values[0].size(-2)
if attention_mask is not None and len(attention_mask.shape) == 2 and position_ids is None:
# create position_ids on the fly for batch generation
position_ids = attention_mask.long().cumsum(-1) - 1
position_ids.masked_fill_(attention_mask == 0, 1)
if past_length > 0:
position_ids = position_ids[:, past_length : input_shape[-1] + past_length :]
elif position_ids is None:
position_ids = torch.arange(past_length, input_shape[-1] + past_length, dtype=torch.long, device=device)
position_ids = position_ids.unsqueeze(0)
# Self-attention mask.
query_length = input_shape[-1]
key_length = past_length + query_length
self_attention_mask = self.bias[None, key_length - query_length : key_length, :key_length]
if self._use_flash_attention_2:
# 2d mask is passed through the layers
attention_mask = attention_mask.bool() if (attention_mask is not None and 0 in attention_mask) else None
encoder_attention_mask = (
encoder_attention_mask.bool()
if (encoder_attention_mask is not None and 0 in encoder_attention_mask)
else None