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- # Copyright (c) 2025 Baidu, Inc. All Rights Reserved.
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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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-
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- from typing import Optional, Tuple, Union
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-
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- import torch
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- import torch.nn as nn
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- import torch.nn.functional as F
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- from torch.nn.attention import SDPBackend, sdpa_kernel
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-
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- from transformers.activations import ACT2FN
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- from transformers.modeling_utils import PreTrainedModel
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- from transformers.generation import GenerationMixin
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- from transformers.modeling_outputs import (
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- BaseModelOutputWithPast,
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- CausalLMOutputWithPast,
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- )
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- from transformers.utils import logging
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-
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- from .configuration_ernie4_5 import Ernie4_5_Config
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-
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-
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- logger = logging.get_logger(__name__)
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-
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-
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- class Ernie4_5_RMSNorm(nn.Module):
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- """
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- Root Mean Square Layer Normalization (Ernie4_5_RMSNorm) implementation.
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-
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- Ernie4_5_RMSNorm is a simplified version of LayerNorm that focuses on the root mean square of inputs,
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- omitting the mean-centering operation. This provides computational efficiency while maintaining
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- good performance.
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- """
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-
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- def __init__(self, config):
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- """
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- Initialize Ernie4_5_RMSNorm layer.
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-
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- Args:
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- config: Model configuration.
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- """
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- super().__init__()
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- self.hidden_size = config.hidden_size
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- self.weight = nn.Parameter(
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- torch.ones(self.hidden_size, dtype=torch.get_default_dtype())
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- )
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- self.variance_epsilon = config.rms_norm_eps
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-
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- def forward(self, hidden_states):
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- """
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- Apply RMS normalization to input hidden states.
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-
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- Args:
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- hidden_states (Tensor): Input tensor of shape [batch_size, seq_len, hidden_size]
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-
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- Returns:
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- Tensor: Normalized output tensor of same shape as input
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-
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- Note:
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- - computes Ernie4_5_RMSNorm manually:
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- 1. Compute variance of features
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- 2. Apply reciprocal square root normalization
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- 3. Scale by learned weight parameter
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- - Maintains original dtype for numerical stability during computation
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- """
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- variance = hidden_states.to(torch.float32).pow(2).mean(-1, keepdim=True)
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- hidden_states = torch.rsqrt(variance + self.variance_epsilon) * hidden_states
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- return hidden_states.to(self.weight.dtype) * self.weight
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-
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-
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- class Ernie4_5_RopeEmbedding(nn.Module):
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- """
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- Rotary Position Embedding (RoPE) implementation for transformer models.
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-
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- RoPE encodes absolute positional information with rotation matrices and
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- naturally incorporates relative position information in self-attention.
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-
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- Args:
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- head_dim (int): Dimension size of each attention head
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- compression_ratio (float, optional): Sequence length compression ratio. Defaults to 1.0.
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- base (int, optional): Base value for frequency calculation. Defaults to 10000.
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-
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- Attributes:
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- head_dim (int): Dimension size of each attention head
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- compression_ratio (float): Sequence length compression factor
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- base (int): Base value for frequency calculation
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- """
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-
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- def __init__(self, head_dim, compression_ratio=1.0, base=10000):
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- """
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- Initialize RoPE embedding layer.
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-
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- Args:
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- head_dim: Dimension of each attention head
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- compression_ratio: Scaling factor for position indices
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- base: Base value for frequency calculation
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- """
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- super().__init__()
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- self.head_dim = head_dim
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- self.compression_ratio = compression_ratio
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- self.base = base
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-
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- def forward(self, seq_length, position_ids=None):
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- """
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- Compute rotary position embeddings for given sequence length.
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-
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- Args:
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- seq_length (int): Maximum sequence length
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- position_ids (Tensor, optional): Custom position indices. Defaults to None.
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-
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- Returns:
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- Tensor: Rotary position embeddings of shape [1, 1, seq_length, head_dim]
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- """
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- indices = torch.arange(0, self.head_dim, 2, dtype=torch.float32)
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- indices = 1 / self.base ** (indices / self.head_dim)
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- if position_ids is None:
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- position_ids = torch.arange(
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- 0, seq_length, 1, dtype=torch.float32
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- ).unsqueeze(1)
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- position_ids = position_ids / self.compression_ratio
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- sinusoid_inp = position_ids * indices.unsqueeze(0)
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- else:
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- position_ids = position_ids / self.compression_ratio
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- seq_length = position_ids.shape[-1]
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- sinusoid_inp = position_ids.unsqueeze(-1).to(
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- torch.float32
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- ) * indices.unsqueeze(0)
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- pos_emb = torch.cat([torch.sin(sinusoid_inp), torch.cos(sinusoid_inp)], dim=-1)
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- pos_emb = pos_emb.view(-1, 1, seq_length, self.head_dim)
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- pos_emb = pos_emb.detach()
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- return pos_emb
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-
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- def apply_rotary(self, rp, q, k):
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- """
146
- Apply rotary position embeddings to queries and keys.
147
-
148
- Args:
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- rp (Tensor): Rotary position embeddings
150
- q (Tensor): Query tensor [batch, heads, seq_len, dim]
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- k (Tensor): Key tensor [batch, heads, seq_len, dim]
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-
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- Returns:
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- Tuple[Tensor, Tensor]: Rotated queries and keys
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- """
156
- sin, cos = torch.chunk(rp.to(q.device), 2, dim=-1)
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- # sin [θ0,θ1,θ2......θd/2-1] -> sin_pos [θ0,θ0,θ1,θ1,θ2,θ2......θd/2-1,θd/2-1]
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- sin_pos = torch.stack([sin, sin], dim=-1).reshape(rp.shape)
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- # cos [θ0,θ1,θ2......θd/2-1] -> cos_pos [θ0,θ0,θ1,θ1,θ2,θ2......θd/2-1,θd/2-1]
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- cos_pos = torch.stack([cos, cos], dim=-1).reshape(rp.shape)
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- # rotate_half_query_layer [-q1,q0,-q3,q2......,-qd-1,qd-2]
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- rotate_half_q = torch.stack(
163
- [-q[:, :, :, 1::2], q[:, :, :, 0::2]], dim=-1
164
- ).reshape(q.shape)
165
- query = (q.to(torch.float32) * cos_pos) + (
166
- rotate_half_q.to(torch.float32) * sin_pos
167
- )
168
- # rotate_half_key_layer [-k1,k0,-k3,k2......,-kd-1,kd-2]
169
- rotate_half_k = torch.stack(
170
- [-k[:, :, :, 1::2], k[:, :, :, 0::2]], dim=-1
171
- ).reshape(k.shape)
172
- key = (k.to(torch.float32) * cos_pos) + (
173
- rotate_half_k.to(torch.float32) * sin_pos
174
- )
175
- return query, key
176
-
177
-
178
- class Ernie4_5_FusedDropoutImpl(nn.Module):
179
- """
180
- Fused dropout implementation with residual connection support.
181
-
182
- This layer combines dropout and residual addition in a single operation for better performance,
183
- particularly on GPU devices. The dropout is conditionally applied based on the probability.
184
-
185
- Args:
186
- prob (float): Dropout probability (between 0 and 1)
187
-
188
- Attributes:
189
- prob (float): Stores the dropout probability
190
- dropout (nn.Dropout): The actual dropout layer instance
191
- """
192
-
193
- def __init__(self, prob):
194
- """
195
- Initialize the fused dropout layer.
196
-
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- Args:
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- prob (float): Dropout probability (0 means no dropout)
199
- """
200
- super().__init__()
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- self.prob = prob
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- self.dropout = nn.Dropout(p=prob)
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-
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- def forward(self, x, y):
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- """
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- Forward pass of the fused dropout layer.
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-
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- Args:
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- x (Tensor): Input tensor to potentially apply dropout
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- y (Tensor): Residual tensor to add to the (possibly dropped out) x
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-
212
- Returns:
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- Tensor: Result of x (with optional dropout) + y
214
- """
215
- if self.prob > 0:
216
- x = self.dropout(x)
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- output = x + y
218
-
219
- return output
220
-
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-
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- class Ernie4_5_MLP(nn.Module):
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- """
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- Ernie4_5_MLP - Gated Multi-Layer Perceptron module used in Ernie model.
225
- """
226
-
227
- def __init__(self, config, layer_idx=0):
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- """
229
- Initialize the MLP module with configuration options.
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-
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- Args:
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- config: Model configurations.
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- layer_idx (int): Index of current layer (default: 0)
234
- """
235
- super().__init__()
236
- self.config = config
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- self.layer_idx = layer_idx
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- self.hidden_size = config.hidden_size
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- self.intermediate_size = config.intermediate_size
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-
241
- self.gate_proj = nn.Linear(
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- self.hidden_size, self.intermediate_size, bias=config.use_bias
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- )
244
- self.up_proj = nn.Linear(
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- self.hidden_size, self.intermediate_size, bias=config.use_bias
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- )
247
- self.down_proj = nn.Linear(
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- self.intermediate_size, self.hidden_size, bias=config.use_bias
249
- )
250
- self.act_fn = ACT2FN[config.hidden_act]
251
-
252
- def forward(self, x):
253
- """
254
- Args:
255
- x (Tensor): shape [batch_size, seq_len, hidden_size]
256
-
257
- Returns:
258
- Tensor: shape [batch_size, seq_len, hidden_size]
259
- """
260
- down_proj = self.down_proj(self.act_fn(self.gate_proj(x)) * self.up_proj(x))
261
- return down_proj
262
-
263
-
264
- class Ernie4_5_Attention(nn.Module):
265
- """Multi-headed attention from 'Attention Is All You Need' paper"""
266
-
267
- def __init__(self, config, layer_idx=0):
268
- """Initialize the attention layer.
269
-
270
- Args:
271
- config: Model configuration.
272
- layer_idx (int, optional): Index in transformer stack. Defaults to 0.
273
- """
274
- super().__init__()
275
- self.layer_idx = layer_idx
276
- self.hidden_size = config.hidden_size
277
- self.num_heads = config.num_attention_heads
278
- self.num_key_value_heads = config.num_key_value_heads
279
-
280
- if config.head_dim is None:
281
- self.head_dim = self.hidden_size // self.num_heads
282
- else:
283
- self.head_dim = config.head_dim
284
-
285
- self.is_gqa = (
286
- self.num_key_value_heads is not None
287
- and self.num_key_value_heads != self.num_heads
288
- )
289
-
290
- if self.is_gqa:
291
- logger.info(
292
- f"use GQA - num_heads: {self.num_heads}- num_key_value_heads: {self.num_key_value_heads}"
293
- )
294
- assert (
295
- self.num_heads % self.num_key_value_heads == 0
296
- ), f"num_heads: {self.num_heads}, num_key_value_heads: {self.num_key_value_heads}"
297
- kv_hidden_size = self.head_dim * self.num_key_value_heads
298
- q_hidden_size = self.head_dim * self.num_heads
299
- else:
300
- q_hidden_size = kv_hidden_size = self.head_dim * self.num_heads
301
-
302
- self.q_proj = nn.Linear(self.hidden_size, q_hidden_size, bias=config.use_bias)
303
- self.k_proj = nn.Linear(self.hidden_size, kv_hidden_size, bias=config.use_bias)
304
- self.v_proj = nn.Linear(self.hidden_size, kv_hidden_size, bias=config.use_bias)
305
- self.o_proj = nn.Linear(q_hidden_size, self.hidden_size, bias=config.use_bias)
306
-
307
- self.rotary_emb = Ernie4_5_RopeEmbedding(
308
- self.head_dim,
309
- compression_ratio=config.compression_ratio,
310
- base=config.rope_theta,
311
- )
312
- self.config = config
313
-
314
- self.set_attn_func()
315
-
316
- def set_attn_func(self):
317
- """Configure attention function based on settings.
318
-
319
- Selects between flash/core attention.
320
- """
321
- config = self.config
322
- if config.use_flash_attention:
323
- self.attn_func = self._flash_attention_wrapper
324
- else:
325
- self.attn_func = self.core_attn
326
-
327
- def forward(
328
- self,
329
- hidden_states,
330
- past_key_value: Optional[Tuple[torch.Tensor]] = None,
331
- attention_mask: Optional[torch.Tensor] = None,
332
- attn_mask_start_row_indices: Optional[torch.Tensor] = None,
333
- position_ids: Optional[Tuple[torch.Tensor]] = None,
334
- output_attentions: bool = False,
335
- use_cache: bool = False,
336
- token_type_ids: Optional[Tuple[torch.Tensor]] = None,
337
- ) -> Tuple[torch.Tensor, Optional[torch.Tensor], Optional[Tuple[torch.Tensor]]]:
338
- """Compute attention outputs.
339
-
340
- Args:
341
- hidden_states (torch.Tensor): Input tensor [bsz, seq_len, hidden_size]
342
- past_key_value (Optional[Tuple[torch.Tensor, torch.Tensor]]): Cached key/value states
343
- attention_mask (Optional[torch.Tensor]): Attention mask tensor
344
- attn_mask_start_row_indices (Optional[torch.Tensor]): Variable length attention indices
345
- position_ids (Optional[torch.Tensor]): Position indices for RoPE
346
- output_attentions (bool): Return attention weights if True
347
- use_cache (bool): Cache key/value states if True
348
-
349
- Returns:
350
- Tuple containing:
351
- - attention_output: [bsz, seq_len, hidden_size]
352
- - attention_weights: Optional attention probabilities
353
- - updated_key_value_cache: Optional updated cache
354
- """
355
- if token_type_ids is not None:
356
- token_type_ids = token_type_ids[:, :-1]
357
-
358
- bsz, q_len, _ = hidden_states.shape
359
-
360
- query_states = self.q_proj(hidden_states).reshape(
361
- [bsz, q_len, -1, self.head_dim]
362
- )
363
- key_states = self.k_proj(hidden_states).reshape([bsz, q_len, -1, self.head_dim])
364
- value_states = self.v_proj(hidden_states).reshape(
365
- [bsz, q_len, -1, self.head_dim]
366
- )
367
-
368
- attn_output, attn_weights, past_key_value = self.rope_attn(
369
- query_states=query_states,
370
- key_states=key_states,
371
- value_states=value_states,
372
- attention_mask=attention_mask,
373
- position_ids=position_ids,
374
- output_attentions=output_attentions,
375
- past_key_value=past_key_value,
376
- use_cache=use_cache,
377
- attn_mask_start_row_indices=attn_mask_start_row_indices,
378
- )
379
-
380
- attn_output = self.o_proj(attn_output)
381
-
382
- if not output_attentions:
383
- attn_weights = None
384
-
385
- return attn_output, attn_weights, past_key_value
386
-
387
- def repeat_kv(self, hidden_states, n_rep):
388
- """
389
- This is the equivalent of torch.repeat_interleave(x, dim=1, repeats=n_rep). The hidden states go from (batch,
390
- num_key_value_heads, seqlen, head_dim) to (batch, num_attention_heads, seqlen, head_dim)
391
- """
392
- batch, num_key_value_heads, slen, head_dim = hidden_states.shape
393
- if n_rep == 1:
394
- return hidden_states
395
- hidden_states = hidden_states[:, :, None, :, :].expand(
396
- batch, num_key_value_heads, n_rep, slen, head_dim
397
- )
398
- return hidden_states.reshape(batch, num_key_value_heads * n_rep, slen, head_dim)
399
-
400
- def _flash_attention_wrapper(
401
- self,
402
- q,
403
- k,
404
- v,
405
- attention_mask=None,
406
- attn_mask_start_row_indices=None,
407
- seq_length=None,
408
- ):
409
- """Wrapper for flash attention implementation.
410
-
411
- Args:
412
- q (torch.Tensor): Query tensor
413
- k (torch.Tensor): Key tensor
414
- v (torch.Tensor): Value tensor
415
- attention_mask (Optional[torch.Tensor]): Attention mask
416
- attn_mask_start_row_indices (Optional[torch.Tensor]): Variable length indices
417
- seq_length (Optional[int]): Sequence length
418
-
419
- Returns:
420
- Tuple[torch.Tensor, torch.Tensor]: Attention output and weights
421
- """
422
- q = q.transpose(1, 2)
423
- k = k.transpose(1, 2)
424
- v = v.transpose(1, 2)
425
-
426
- with sdpa_kernel(SDPBackend.FLASH_ATTENTION):
427
- out = F.scaled_dot_product_attention(
428
- q,
429
- k,
430
- v,
431
- attn_mask=None,
432
- dropout_p=self.config.attention_probs_dropout_prob,
433
- is_causal=q.shape[2] != 1,
434
- scale=1
435
- / (getattr(self.config, "scale_qk_coeff", 1.0) * self.head_dim**0.5),
436
- enable_gqa=self.is_gqa,
437
- )
438
- out = out.transpose(1, 2)
439
- out = out.contiguous().view(out.size(0), out.size(1), -1)
440
-
441
- return out, None
442
-
443
- def core_attn(
444
- self,
445
- q,
446
- k,
447
- v,
448
- attention_mask=None,
449
- attn_mask_start_row_indices=None,
450
- seq_length=None,
451
- ):
452
- """Standard self-attention implementation.
453
-
454
- Args:
455
- q (torch.Tensor): Query tensor
456
- k (torch.Tensor): Key tensor
457
- v (torch.Tensor): Value tensor
458
- attention_mask (Optional[torch.Tensor]): Attention mask
459
- attn_mask_start_row_indices (Optional[torch.Tensor]): Variable length indices
460
- seq_length (Optional[int]): Sequence length
461
-
462
- Returns:
463
- Tuple[torch.Tensor, torch.Tensor]: Attention output and weights
464
- """
465
- origin_dtype = q.dtype
466
-
467
- q = q.permute(0, 2, 1, 3)
468
- k = k.permute(0, 2, 1, 3)
469
- v = v.permute(0, 2, 1, 3)
470
-
471
- scale_qk_coeff = (
472
- getattr(self.config, "scale_qk_coeff", 1.0) * self.head_dim**0.5
473
- )
474
-
475
- q = q / scale_qk_coeff
476
-
477
- # Handle GQA case - repeat k and v heads to match q heads
478
- if self.is_gqa:
479
- # [batch, num_key_value_heads, seq_len, head_dim] -> [batch, num_heads, seq_len, head_dim]
480
- repeat_factor = self.num_heads // self.num_key_value_heads
481
- k = self.repeat_kv(k, repeat_factor)
482
- v = self.repeat_kv(v, repeat_factor)
483
-
484
- attn_scores = torch.matmul(q, k.transpose(-2, -1))
485
-
486
- if getattr(self.config, "scale_qk_coeff", 1.0) != 1.0:
487
- attn_scores = attn_scores * getattr(self.config, "scale_qk_coeff", 1.0)
488
-
489
- # Causal mask
490
- seq_len = attn_scores.size(-1)
491
- mask = torch.triu(
492
- torch.ones((seq_len, seq_len), dtype=torch.bool, device=attn_scores.device),
493
- diagonal=1,
494
- )
495
- attn_scores = attn_scores.masked_fill(mask, float("-inf"))
496
- attn_weights = F.softmax(attn_scores, dim=-1)
497
-
498
- attn_weights = attn_weights.to(origin_dtype)
499
-
500
- # attention_probs_dropout_prob default 0.0
501
- if getattr(self.config, "attention_probs_dropout_prob", 0.0) > 0:
502
- attn_weights = F.dropout(
503
- attn_weights,
504
- p=self.config.attention_probs_dropout_prob,
505
- training=self.training,
506
- )
507
-
508
- # [batch, num_heads, q_len, k_len] @ [batch, num_heads, k_len, head_dim] -> [batch, num_heads, q_len, head_dim]
509
- out = torch.matmul(attn_weights, v)
510
-
511
- # [batch, num_heads, seq_len, head_dim] -> [batch, seq_len, num_heads, head_dim]
512
- out = out.permute(0, 2, 1, 3)
513
- # [batch, seq_len, hidden_size]
514
- out = out.contiguous().view(out.size(0), out.size(1), -1)
515
-
516
- return out, attn_weights
517
-
518
- def rope_attn(
519
- self,
520
- query_states,
521
- key_states,
522
- value_states,
523
- attention_mask,
524
- position_ids,
525
- output_attentions=False,
526
- past_key_value=None,
527
- use_cache=False,
528
- attn_mask_start_row_indices=None,
529
- ):
530
- """Attention computation with rotary embeddings.
531
-
532
- Args:
533
- query_states (torch.Tensor): Query states
534
- key_states (torch.Tensor): Key states
535
- value_states (torch.Tensor): Value states
536
- attention_mask (Optional[torch.Tensor]): Attention mask
537
- position_ids (Optional[torch.Tensor]): Position indices
538
- output_attentions (bool): Return attention weights
539
- past_key_value (Optional[Tuple[torch.Tensor, torch.Tensor]]): Cached states
540
- use_cache (bool): Cache new states
541
- attn_mask_start_row_indices (Optional[torch.Tensor]): Variable length indices
542
-
543
- Returns:
544
- Tuple containing:
545
- - attention_output: Result tensor
546
- - attention_weights: Optional weights
547
- - updated_key_value_cache: Optional cache
548
- """
549
-
550
- query_states_dtype = query_states.dtype
551
-
552
- kv_seq_len = key_states.shape[-3]
553
- offset = 0
554
- if past_key_value is not None:
555
- offset = past_key_value[0].shape[-3]
556
- kv_seq_len += offset
557
-
558
- cos_sin = self.rotary_emb(kv_seq_len).permute(
559
- [0, 2, 1, 3]
560
- ) # [b,h,s,d]->[b,s,h,d]
561
- if offset > 0:
562
- cos_sin = cos_sin[:, offset:]
563
- query_states, key_states = self.rotary_emb.apply_rotary(
564
- cos_sin, query_states, key_states
565
- )
566
-
567
- query_states = query_states.to(query_states_dtype)
568
- key_states = key_states.to(query_states_dtype)
569
- if past_key_value is not None:
570
- # reuse k, v, self_attention
571
- key_states = torch.cat([past_key_value[0], key_states], dim=1)
572
- value_states = torch.cat([past_key_value[1], value_states], dim=1)
573
-
574
- # shape: [2, b, s, kvh, d]
575
- past_key_value = [key_states, value_states] if use_cache else None
576
- seq_length = query_states.shape[1]
577
- attn_output, attn_weights = self.attn_func(
578
- query_states,
579
- key_states,
580
- value_states,
581
- attention_mask,
582
- attn_mask_start_row_indices,
583
- seq_length,
584
- )
585
- return attn_output, attn_weights, past_key_value
586
-
587
-
588
- class Ernie4_5_DecoderLayer(nn.Module):
589
- """
590
- A single transformer decoder layer in ERNIE model.
591
- """
592
-
593
- def __init__(self, config, layer_idx):
594
- """Initialize the decoder layer.
595
-
596
- Args:
597
- config: Model configuration.
598
- layer_idx (int): Index of this layer in the transformer stack
599
- """
600
- super().__init__()
601
- self.hidden_size = config.hidden_size
602
- self.layer_idx = layer_idx
603
- self.config = config
604
-
605
- self.self_attn = Ernie4_5_Attention(config, layer_idx)
606
- self.mlp = Ernie4_5_MLP(config)
607
-
608
- self.input_layernorm = Ernie4_5_RMSNorm(config)
609
- self.post_attention_layernorm = Ernie4_5_RMSNorm(config)
610
-
611
- self.residual_add1 = Ernie4_5_FusedDropoutImpl(config.hidden_dropout_prob)
612
- self.residual_add2 = Ernie4_5_FusedDropoutImpl(config.hidden_dropout_prob)
613
-
614
- def forward(
615
- self,
616
- hidden_states: torch.Tensor,
617
- attention_mask: Optional[torch.Tensor] = None,
618
- attn_mask_start_row_indices: Optional[torch.Tensor] = None,
619
- position_ids: Optional[torch.Tensor] = None,
620
- token_type_ids: Optional[torch.Tensor] = None,
621
- output_attentions: Optional[bool] = False,
622
- past_key_value: Optional[Tuple[torch.Tensor]] = None,
623
- use_cache: Optional[bool] = False,
624
- ) -> Tuple[torch.Tensor, Optional[Tuple[torch.Tensor, torch.Tensor]]]:
625
- """Forward pass through the decoder layer.
626
-
627
- Args:
628
- hidden_states (torch.Tensor): Input tensor [batch_size, seq_len, hidden_size]
629
- attention_mask (Optional[torch.Tensor]): Attention mask tensor
630
- attn_mask_start_row_indices (Optional[torch.Tensor]): Indices for variable length attention
631
- position_ids (Optional[torch.Tensor]): Position indices for rotary embeddings
632
- output_attentions (Optional[bool]): Whether to return attention weights
633
- past_key_value (Optional[Tuple[torch.Tensor]]): Cached key/value states
634
- use_cache (Optional[bool]): Whether to cache key/value states
635
-
636
- Returns:
637
- Union: Various output combinations depending on arguments:
638
- - Base case: Hidden states tensor
639
- - With attention: Tuple of (hidden_states, attention_weights)
640
- - With cache: Tuple of (hidden_states, cached_key_value)
641
- """
642
- residual = hidden_states
643
-
644
- hidden_states = self.input_layernorm(hidden_states)
645
-
646
- # Self Attention
647
- (hidden_states, self_attn_weights, present_key_value) = self.self_attn(
648
- hidden_states=hidden_states,
649
- past_key_value=past_key_value,
650
- attention_mask=attention_mask,
651
- attn_mask_start_row_indices=attn_mask_start_row_indices,
652
- position_ids=position_ids,
653
- output_attentions=output_attentions,
654
- use_cache=use_cache,
655
- token_type_ids=token_type_ids,
656
- )
657
- hidden_states = self.residual_add1(hidden_states, residual)
658
-
659
- # Fully Connected
660
- residual = hidden_states
661
- hidden_states = self.post_attention_layernorm(hidden_states)
662
- hidden_states = self.mlp(hidden_states)
663
-
664
- hidden_states = self.residual_add2(hidden_states, residual)
665
- outputs = (hidden_states,)
666
-
667
- if output_attentions:
668
- outputs += (self_attn_weights,)
669
-
670
- if use_cache:
671
- outputs += (present_key_value,)
672
-
673
- if type(outputs) is tuple and len(outputs) == 1:
674
- outputs = outputs[0]
675
-
676
- return outputs
677
-
678
-
679
- class Ernie4_5_PretrainedModel(PreTrainedModel):
680
- """Base class for ERNIE pretrained models."""
681
-
682
- config_class = Ernie4_5_Config
683
- base_model_prefix = "ernie"
684
-
685
-
686
- class Ernie4_5_Model(Ernie4_5_PretrainedModel):
687
-
688
- def __init__(self, config):
689
- """Initialize the ERNIE model architecture.
690
-
691
- Args:
692
- config: Model configuration.
693
- """
694
- super().__init__(config)
695
- self.padding_idx = config.pad_token_id
696
- self.vocab_size = config.vocab_size
697
- self.hidden_size = config.hidden_size
698
- self.config = config
699
-
700
- self.embed_tokens = nn.Embedding(
701
- self.vocab_size,
702
- self.hidden_size,
703
- )
704
-
705
- self.layers = nn.ModuleList(
706
- [Ernie4_5_DecoderLayer(config, i) for i in range(config.num_hidden_layers)]
707
- )
708
-
709
- self.norm = Ernie4_5_RMSNorm(config)
710
-
711
- self.gradient_checkpointing = False
712
-
713
- def get_input_embeddings(self):
714
- """Get the input embedding layer.
715
-
716
- Returns:
717
- nn.Embedding: The embedding layer for input tokens
718
- """
719
- return self.embed_tokens
720
-
721
- def set_input_embeddings(self, value):
722
- """Set new input embeddings.
723
-
724
- Args:
725
- value (nn.Embedding): New embedding layer to use
726
- """
727
- self.embed_tokens = value
728
-
729
- def forward(
730
- self,
731
- input_ids=None,
732
- position_ids=None,
733
- token_type_ids=None,
734
- attention_mask=None,
735
- attn_mask_start_row_indices=None,
736
- inputs_embeds=None,
737
- use_cache=None,
738
- past_key_values=None,
739
- output_attentions=False,
740
- output_hidden_states=None,
741
- return_dict=False,
742
- ):
743
- """Forward pass through the ERNIE model.
744
-
745
- Args:
746
- input_ids (Optional[torch.Tensor]): Input token IDs
747
- position_ids (Optional[torch.Tensor]): Position indices
748
- attention_mask (Optional[torch.Tensor]): Attention mask
749
- attn_mask_start_row_indices (Optional[torch.Tensor]): Variable length attention indices
750
- inputs_embeds (Optional[torch.Tensor]): Precomputed embeddings
751
- use_cache (Optional[bool]): Whether to cache key/value states
752
- past_key_values (Optional[Tuple[Tuple[torch.Tensor]]]): Cached key/value states
753
- output_attentions (Optional[bool]): Whether to output attention weights
754
- output_hidden_states (Optional[bool]): Whether to output all hidden states
755
- return_dict (Optional[bool]): Whether to return dict or tuple
756
-
757
- Returns:
758
- Union[Tuple, BaseModelOutputWithPast]:
759
- Various outputs depending on configuration, including:
760
- - last_hidden_state: Final layer hidden states
761
- - past_key_values: Cached key/value states if use_cache=True
762
- - hidden_states: All hidden states if output_hidden_states=True
763
- - attentions: Attention weights if output_attentions=True
764
- """
765
- use_cache = use_cache if use_cache is not None else self.config.use_cache
766
-
767
- # retrieve input_ids and inputs_embeds
768
- if input_ids is not None and inputs_embeds is not None:
769
- raise ValueError(
770
- "You cannot specify both decoder_input_ids and decoder_inputs_embeds at the same time"
771
- )
772
- elif input_ids is not None:
773
- _, seq_length = input_ids.shape
774
- elif inputs_embeds is not None:
775
- _, seq_length, _ = inputs_embeds.shape
776
- else:
777
- raise ValueError(
778
- "You have to specify either decoder_input_ids or decoder_inputs_embeds"
779
- )
780
-
781
- if past_key_values is None:
782
- past_key_values = tuple([None] * len(self.layers))
783
-
784
- if inputs_embeds is None:
785
- inputs_embeds = self.embed_tokens(input_ids)
786
- inputs_embeds = inputs_embeds.to(self.embed_tokens.weight.dtype)
787
-
788
- hidden_states = inputs_embeds
789
-
790
- # decoder layers
791
- all_hidden_states = () if output_hidden_states else None
792
- all_self_attns = () if output_attentions else None
793
- next_decoder_cache = () if use_cache else None
794
-
795
- for idx, (decoder_layer) in enumerate(self.layers):
796
-
797
- if output_hidden_states:
798
- all_hidden_states += (hidden_states,)
799
-
800
- past_key_value = (
801
- past_key_values[idx] if past_key_values is not None else None
802
- )
803
-
804
- layer_outputs = decoder_layer(
805
- hidden_states,
806
- attention_mask,
807
- attn_mask_start_row_indices,
808
- position_ids,
809
- token_type_ids,
810
- output_attentions,
811
- past_key_value,
812
- use_cache,
813
- )
814
-
815
- if isinstance(layer_outputs, (tuple, list)):
816
- hidden_states = layer_outputs[0]
817
- else:
818
- hidden_states = layer_outputs
819
-
820
- if use_cache:
821
- next_decoder_cache += (layer_outputs[2 if output_attentions else 1],)
822
-
823
- if output_attentions:
824
- all_self_attns += (layer_outputs[1],)
825
-
826
- # apply kv cache
827
- if past_key_value is not None:
828
- hidden_states = hidden_states[:, -1:, :]
829
-
830
- hidden_states = self.norm(hidden_states)
831
-
832
- # add hidden states from the last decoder layer
833
- if output_hidden_states:
834
- all_hidden_states += (hidden_states,)
835
-
836
- next_cache = next_decoder_cache if use_cache else None
837
-
838
- if not return_dict:
839
- return tuple(
840
- v
841
- for v in [
842
- hidden_states,
843
- next_cache,
844
- all_hidden_states,
845
- all_self_attns,
846
- ]
847
- if v is not None
848
- )
849
-
850
- return BaseModelOutputWithPast(
851
- last_hidden_state=hidden_states,
852
- past_key_values=next_cache,
853
- hidden_states=all_hidden_states,
854
- attentions=all_self_attns,
855
- )
856
-
857
-
858
- class Ernie4_5_LMHead(nn.Module):
859
- """Language model head for ERNIE"""
860
-
861
- def __init__(self, config):
862
- """Initialize the language model head.
863
-
864
- Args:
865
- config: Model configuration containing:
866
- - vocab_size: Size of vocabulary
867
- - hidden_size: Dimension of hidden states
868
- - tie_word_embeddings: Whether to tie input/output embeddings
869
- - weight_share_add_bias: Whether to add bias when weight sharing
870
- - use_bias: Whether to use bias term
871
- """
872
-
873
- super(Ernie4_5_LMHead, self).__init__()
874
- self.config = config
875
- vocab_size = config.vocab_size
876
-
877
- if config.tie_word_embeddings:
878
- # Weight of shape [vocab_size, hidden_size]
879
- self.weight = nn.Parameter(
880
- torch.empty(
881
- vocab_size, config.hidden_size, dtype=torch.get_default_dtype()
882
- )
883
- )
884
- else:
885
- # Weight of shape [hidden_size, vocab_size]
886
- self.weight = nn.Parameter(
887
- torch.empty(
888
- config.hidden_size, vocab_size, dtype=torch.get_default_dtype()
889
- )
890
- )
891
- nn.init.xavier_uniform_(self.weight)
892
-
893
- logger.info(
894
- f"output-weight: {self.weight.shape}, tie_word_embeddings: {config.tie_word_embeddings}"
895
- )
896
-
897
- if config.weight_share_add_bias and config.use_bias:
898
- self.bias = nn.Parameter(
899
- torch.zeros(vocab_size, dtype=torch.get_default_dtype())
900
- )
901
- else:
902
- self.bias = None
903
-
904
- def forward(self, hidden_states):
905
- """Project hidden states to vocabulary logits.
906
-
907
- Args:
908
- hidden_states (torch.Tensor): Input tensor of shape [batch_size, seq_len, hidden_size]
909
-
910
- Returns:
911
- Logits tensor of shape [batch_size, seq_len, vocab_size]
912
- """
913
- return self.calc_lm_head_logits(
914
- self.config, hidden_states, self.weight, self.bias
915
- )
916
-
917
- def calc_lm_head_logits(self, config, hidden_states, weight, bias):
918
- """
919
- Calculate language model head logits.
920
-
921
- This is the core function that computes the final output logits for a language model.
922
-
923
- Args:
924
- config: Model configuration.
925
- hidden_states (Tensor): Hidden states from the transformer layers
926
- weight (Tensor): Weight matrix for the language model head
927
- bias (Tensor): Bias vector for the language model head
928
-
929
- Returns:
930
- Tensor: The computed logits for language modeling.
931
- """
932
-
933
- if config.tie_word_embeddings:
934
- logits = torch.matmul(hidden_states, weight.T)
935
- else:
936
- logits = torch.matmul(hidden_states, weight)
937
-
938
- if bias is not None:
939
- logits = logits + bias
940
-
941
- return logits
942
-
943
-
944
- class Ernie4_5_ForCausalLM(Ernie4_5_PretrainedModel, GenerationMixin):
945
- """ERNIE model for causal language modeling."""
946
-
947
- _tied_weights_keys = ["lm_head.weight"]
948
- _tp_plan = {"lm_head": "colwise_rep"}
949
- _pp_plan = {"lm_head": (["hidden_states"], ["logits"])}
950
-
951
- def __init__(self, config):
952
- """
953
- Initializes the ERNIE model for causal language modeling.
954
-
955
- Args:
956
- config: Model configuration.
957
- """
958
- super().__init__(config)
959
-
960
- self.config = config
961
- self.model = Ernie4_5_Model(config)
962
- self.lm_head = Ernie4_5_LMHead(config)
963
-
964
- # Initialize weights and apply final processing
965
- self.post_init()
966
-
967
- @torch.no_grad()
968
- def set_state_dict(self, state_dict, *args, **kwargs):
969
- """
970
- Loads the model state dictionary.
971
- """
972
- ret = super().set_state_dict(state_dict)
973
- return ret
974
-
975
- def get_input_embeddings(self):
976
- """Returns the input embeddings layer."""
977
- return self.model.embed_tokens
978
-
979
- def set_input_embeddings(self, value):
980
- """Sets the input embeddings layer."""
981
- self.model.embed_tokens = value
982
-
983
- def get_output_embeddings(self):
984
- """Returns the output embeddings (LM head)."""
985
- return self.lm_head
986
-
987
- def set_output_embeddings(self, new_embeddings):
988
- """Sets the output embeddings layer."""
989
- self.lm_head = new_embeddings
990
-
991
- def set_decoder(self, decoder):
992
- """Sets the ERNIE decoder model."""
993
- self.model = decoder
994
-
995
- def get_decoder(self):
996
- """Gets the ERNIE decoder model."""
997
- return self.model
998
-
999
- def forward(
1000
- self,
1001
- input_ids,
1002
- position_ids=None,
1003
- attention_mask=None,
1004
- attn_mask_start_row_indices=None,
1005
- token_type_ids=None,
1006
- inputs_embeds=None,
1007
- labels=None,
1008
- use_cache=False,
1009
- past_key_values=None,
1010
- output_attentions=None,
1011
- output_hidden_states=None,
1012
- **kwargs,
1013
- ):
1014
- """
1015
- Forward pass for causal language modeling.
1016
-
1017
- Args:
1018
- input_ids (torch.Tensor): Input token IDs.
1019
- position_ids (torch.Tensor): Position IDs.
1020
- attention_mask (torch.Tensor): Attention mask.
1021
- attn_mask_start_row_indices (torch.Tensor): Attention mask start indices.
1022
- inputs_embeds (torch.Tensor): Optional embedded inputs.
1023
- labels (torch.Tensor): Target labels.
1024
- use_cache (bool): Whether to use cached hidden states.
1025
- past_key_values (dict): Pre-computed hidden states.
1026
- output_attentions (bool): Whether to output attentions.
1027
- output_hidden_states (bool): Whether to output hidden states.
1028
-
1029
- Returns:
1030
- CausalLMOutputWithPast: Model outputs.
1031
- """
1032
-
1033
- if past_key_values is not None:
1034
- input_ids = input_ids[:, -1:]
1035
-
1036
- outputs = self.model(
1037
- input_ids,
1038
- position_ids=position_ids,
1039
- attention_mask=attention_mask,
1040
- token_type_ids=token_type_ids,
1041
- attn_mask_start_row_indices=attn_mask_start_row_indices,
1042
- inputs_embeds=inputs_embeds,
1043
- use_cache=use_cache,
1044
- past_key_values=past_key_values,
1045
- output_attentions=output_attentions,
1046
- output_hidden_states=output_hidden_states,
1047
- return_dict=True,
1048
- )
1049
-
1050
- hidden_states = outputs.last_hidden_state
1051
- logits = self.lm_head(hidden_states)
1052
-
1053
- loss = None
1054
- if labels is not None:
1055
- loss = self.loss_function(
1056
- logits=logits,
1057
- labels=labels,
1058
- vocab_size=self.config.vocab_size,
1059
- **kwargs,
1060
- )
1061
-
1062
- return CausalLMOutputWithPast(
1063
- loss=loss,
1064
- logits=logits,
1065
- past_key_values=outputs.past_key_values,
1066
- hidden_states=outputs.hidden_states,
1067
- attentions=outputs.attentions,
1068
- )