modeling_cpmant.py

# coding=utf-8
# Copyright 2022 The OpenBMB Team and The HuggingFace Inc. team. All rights reserved.
#
# 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 CPMAnt"""


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 CrossEntropyLoss

from ...activations import ACT2FN
from ...modeling_outputs import BaseModelOutputWithPast, CausalLMOutputWithPast
from ...modeling_utils import PreTrainedModel
from ...utils import add_code_sample_docstrings, add_start_docstrings, add_start_docstrings_to_model_forward, logging
from .configuration_cpmant import CpmAntConfig


logger = logging.get_logger(__name__)

_CHECKPOINT_FOR_DOC = "openbmb/cpm-ant-10b"
_CONFIG_FOR_DOC = "CpmAntConfig"

CPMANT_PRETRAINED_MODEL_ARCHIVE_LIST = [
    "openbmb/cpm-ant-10b",
    # See all CPMAnt models at https://huggingface.co/models?filter=cpmant
]


class CpmAntLayerNorm(nn.Module):
    """
    We use Root Mean Square (RMS) Layer Normalization, please see https://arxiv.org/abs/1910.07467 for details."
    """

    def __init__(self, config: CpmAntConfig):
        super().__init__()

        self.eps = config.eps
        self.dim_norm = config.hidden_size
        self.weight = nn.Parameter(torch.empty(config.hidden_size))

    def forward(self, hidden_states: torch.Tensor):
        """
        Args:
            hidden_states (`torch.Tensor` of shape `(batch, seq_len, dim_in)`)
        """
        if hidden_states.size(-1) != self.dim_norm:
            raise AssertionError("hidden_states.size(-1) != self.dim_norm")
        old_dtype = hidden_states.dtype
        variance = hidden_states.to(torch.float32).pow(2).mean(dim=-1, keepdim=True)
        hidden_states = (hidden_states * torch.rsqrt(variance + self.eps)).to(old_dtype) * self.weight
        return hidden_states


class CpmAntAttention(nn.Module):
    def __init__(self, config: CpmAntConfig):
        super().__init__()
        self.dim_model = config.hidden_size
        self.num_heads = config.num_attention_heads
        self.dim_head = config.dim_head

        self.project_q = nn.Linear(self.dim_model, self.num_heads * self.dim_head, bias=False)
        self.project_k = nn.Linear(self.dim_model, self.num_heads * self.dim_head, bias=False)
        self.project_v = nn.Linear(self.dim_model, self.num_heads * self.dim_head, bias=False)

        self.attention_out = nn.Linear(self.num_heads * self.dim_head, self.dim_model, bias=False)

        self.softmax = torch.nn.Softmax(dim=-1)

        if config.dropout_p is not None:
            self.dropout = torch.nn.Dropout(p=config.dropout_p)
        else:
            self.dropout = None

    def forward(
        self,
        hidden_q: torch.Tensor,
        hidden_kv: torch.Tensor,
        attention_mask: torch.BoolTensor,
        position_bias: torch.Tensor,
        output_attentions: Optional[bool] = False,
        past_key_values: Optional[Tuple[torch.Tensor, torch.Tensor]] = None,
        use_cache: Optional[bool] = None,
    ):
        """
        Args:
            hidden_q (`torch.Tensor`):
                Input of transformer block(self-attention block). It can be the raw embedding of a batch of sequences.
            hidden_kv (`torch.Tensor` of shape `(batch, len_k, dim_model)`)):
                Tensor *key_value* and *query* of shape `(batch, len_k, dim_model)`
            attention_mask (`torch.Tensor` of shape `(batch, len_seq, len_seq)`):
                Avoid invalid areas to participate in the calculation of self-attention.
            position_bias (`torch.Tensor` of shape `(batch, len_seq, len_seq)`):
                Provide positional information to self-attention block.
            output_attentions (`bool`, *optional*):
                Whether or not to return the attentions tensors of all attention layers.
            past_key_values (`Tuple[torch.Tensor, torch.Tensor]`, *optional*):
                Cached past key and value projection states.
            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`).
        """
        batch_size = hidden_q.size(0)
        len_q = hidden_q.size(1)
        len_k = hidden_kv.size(1)

        query = self.project_q(hidden_q)
        key = self.project_k(hidden_kv)
        value = self.project_v(hidden_kv)

        query = query.view(batch_size, len_q, self.num_heads, self.dim_head).permute(0, 2, 1, 3)
        key = key.view(batch_size, len_k, self.num_heads, self.dim_head).permute(0, 2, 1, 3)
        value = value.view(batch_size, len_k, self.num_heads, self.dim_head).permute(0, 2, 1, 3)

        if past_key_values is not None:
            key = torch.cat([past_key_values[0], key], dim=-2)
            value = torch.cat([past_key_values[1], value], dim=-2)
            len_k = key.size(-2)

        # (batch_size, num_heads, len_q, dim_head) @ (batch_size, num_heads, dim_head, len_k) -> (batch_size, num_heads, len_q, len_k)
        score = torch.matmul(query, key.transpose(-1, -2)) / math.sqrt(self.dim_head)
        score = score + position_bias

        score = torch.masked_fill(
            score,
            attention_mask.view(batch_size, 1, len_q, len_k) == torch.tensor(False),
            torch.scalar_tensor(float("-inf"), device=score.device, dtype=score.dtype),
        )
        score = self.softmax(score)

        score = torch.masked_fill(
            score,
            attention_mask.view(batch_size, 1, len_q, len_k) == torch.tensor(False),
            torch.scalar_tensor(0, device=score.device, dtype=score.dtype),
        )
        if output_attentions:
            attn_weights = score
        else:
            attn_weights = None

        if self.dropout is not None:
            score = self.dropout(score)

        # (batch_size, num_heads, len_q, len_k) @ (batch_size, num_heads, len_k, dim_head) -> (batch_size, num_heads, len_q, dim_head)
        score = torch.matmul(score, value)

        score = score.view(batch_size, self.num_heads, len_q, self.dim_head).permute(0, 2, 1, 3)
        score = score.contiguous().view(batch_size, len_q, self.num_heads * self.dim_head)

        score = self.attention_out(score)

        past_key_values = None
        if use_cache:
            past_key_values = (key, value)

        return score, attn_weights, past_key_values


class CpmAntSelfAttentionBlock(nn.Module):
    def __init__(self, config: CpmAntConfig):
        super().__init__()
        self.layernorm_before_attention = CpmAntLayerNorm(config)
        self.self_attention = CpmAntAttention(config)
        if config.dropout_p:
            self.dropout = torch.nn.Dropout(config.dropout_p)
        else:
            self.dropout = None

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: torch.Tensor,
        position_bias: Optional[torch.Tensor] = None,
        output_attentions: Optional[bool] = False,
        past_key_values: Optional[Tuple[torch.Tensor, torch.Tensor]] = None,
        use_cache: Optional[bool] = None,
    ):
        """
        Args:
            hidden_states (`torch.Tensor` of shape `(batch, len_seq, dim_model)`):
                Input of transformer block(self-attention block). It can be the raw embedding of a batch of sequences.
            attention_mask (`torch.Tensor` of shape `(batch, len_seq, len_seq)`):
                Avoid invalid areas to participate in the calculation of self-attention.
            position_bias (`torch.Tensor` of shape `(batch, len_seq, len_seq)`):
                Provide positional information to self-attention block.
            output_attentions (`bool`, *optional*):
                Whether or not to return the attentions tensors of all attention layers.
            past_key_values (`Tuple(torch.FloatTensor)`, *optional*):
                Cached past key and value projection states.
            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`).
        """
        outputs = self.layernorm_before_attention(hidden_states)
        outputs = self.self_attention(
            outputs, outputs, attention_mask, position_bias, output_attentions, past_key_values, use_cache
        )

        outputs, attn_weights, current_key_value = outputs

        if self.dropout is not None:
            outputs = self.dropout(outputs)
        hidden_states = hidden_states + outputs

        return hidden_states, attn_weights, current_key_value


class CpmAntDenseGatedACT(nn.Module):
    def __init__(self, config: CpmAntConfig):
        super().__init__()
        self.w_0 = nn.Linear(config.hidden_size, config.dim_ff, bias=False)
        self.w_1 = nn.Linear(config.hidden_size, config.dim_ff, bias=False)
        self.act = torch.nn.GELU()

    def forward(self, hidden_states: torch.Tensor):
        """Transform an input tensor from one feature space to another via a nonlinear operation

        Args:
            hidden_states (`torch.Tensor` of shape `(batch, seq_len, dim_in)`)
        """
        gate_score = self.act(self.w_0(hidden_states))
        hidden_states = self.w_1(hidden_states)

        hidden_states = gate_score * hidden_states
        return hidden_states


class CpmAntFeedForward(nn.Module):
    def __init__(self, config: CpmAntConfig):
        super().__init__()
        self.w_in = CpmAntDenseGatedACT(config)
        if config.dropout_p is not None:
            self.dropout = torch.nn.Dropout(config.dropout_p)
        else:
            self.dropout = None

        self.w_out = nn.Linear(config.dim_ff, config.hidden_size, bias=False)

    def forward(self, hidden_states: torch.Tensor):
        """
        Args:
            hidden_states (`torch.Tensor` of shape `(batch, seq_len, dim_in)`)
        """
        hidden_states = self.w_in(hidden_states)

        if self.dropout is not None:
            hidden_states = self.dropout(hidden_states)

        hidden_states = self.w_out(hidden_states)

        return hidden_states


class CpmAntFFNBlock(nn.Module):
    def __init__(self, config: CpmAntConfig):
        super().__init__()
        self.layernorm_before_ffn = CpmAntLayerNorm(config)
        self.ffn = CpmAntFeedForward(config)
        if config.dropout_p:
            self.dropout = torch.nn.Dropout(config.dropout_p)
        else:
            self.dropout = None

    def forward(
        self,
        hidden_states: torch.Tensor,
    ):
        """
        Args:
            hidden_states (`torch.Tensor` of shape `(batch, len_seq, dim_model)`):
                Hidden states before feed forward layer.
        """
        ln_outputs = self.layernorm_before_ffn(hidden_states)
        outputs = self.ffn(ln_outputs)
        if self.dropout is not None:
            outputs = self.dropout(outputs)
        hidden_states = hidden_states + outputs
        return hidden_states


class CpmAntTransformerBlock(nn.Module):
    def __init__(self, config: CpmAntConfig):
        super().__init__()
        self.self_att = CpmAntSelfAttentionBlock(config)
        self.ffn = CpmAntFFNBlock(config)

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: torch.Tensor,
        position_bias: Optional[torch.Tensor] = None,
        output_attentions: Optional[bool] = False,
        past_key_values: Optional[Tuple[torch.Tensor, torch.Tensor]] = None,
        use_cache: Optional[bool] = None,
    ):
        """
        Args:
            hidden_states (`torch.Tensor`):
                Input to the layer of shape `(batch, seq_len, dim_model)`
            attention_mask (`torch.Tensor`):
                Avoid invalid areas to participate in the calculation of shape `(batch, seq_len, seq_len)`
            position_bias (`torch.Tensor`):
                Provides position information to attention mechanism of shape `(num_heads, seq_len, seq_len)`
            output_attentions (`bool`, *optional*):
                Whether or not to return the attentions tensors of all attention layers.
            past_key_values (`Tuple[torch.Tensor, torch.Tensor])`, *optional*):
                Cached past key and value projection states
            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`).
        """
        hidden_states = self.self_att(
            hidden_states,
            attention_mask=attention_mask,
            position_bias=position_bias,
            output_attentions=output_attentions,
            past_key_values=past_key_values,
            use_cache=use_cache,
        )

        hidden_states, attn_weights, current_key_value = hidden_states

        hidden_states = self.ffn(hidden_states)

        return hidden_states, attn_weights, current_key_value


class CpmAntEncoder(nn.Module):
    def __init__(self, config: CpmAntConfig):
        super().__init__()
        self.num_layers = config.num_hidden_layers
        self.layers = nn.ModuleList([CpmAntTransformerBlock(config) for ith in range(self.num_layers)])

        self.output_layernorm = CpmAntLayerNorm(config)

    def forward(
        self,
        hidden_states: torch.Tensor,
        attention_mask: torch.Tensor,
        position_bias: torch.Tensor,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        past_key_values: Optional[Tuple[torch.Tensor, torch.Tensor]] = None,
        use_cache: Optional[bool] = None,
    ):
        """
        Args:
            hidden_states (`torch.Tensor`):
                Input to the layer of shape `(batch, seq_len, dim_model)`
            attention_mask (`torch.Tensor`):
                Avoid invalid areas to participate in the calculation of shape `(batch, seq_len, seq_len)`
            position_bias (`torch.Tensor`):
                Provides position information to attention mechanism of shape `(num_heads, seq_len, seq_len)`
            output_attentions (`bool`, *optional*):
                Whether or not to return the attentions tensors of all attention layers.
            output_hidden_states (`bool`, *optional*):
                Whether or not to return the hidden states of all layers.
            past_key_values (`Tuple[torch.Tensor, torch.Tensor])`, *optional*):
                Cached past key and value projection states
            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`).
        """
        all_hidden_states = () if output_hidden_states else None
        all_self_attns = () if output_attentions else None
        current_key_values = () if use_cache else None

        for i, layer in enumerate(self.layers):
            if output_hidden_states:
                all_hidden_states += (hidden_states,)
            layer_outputs = layer(
                hidden_states,
                attention_mask,
                position_bias,
                output_attentions=output_attentions,
                past_key_values=past_key_values[i] if past_key_values else None,
                use_cache=use_cache,
            )
            hidden_states, attn_weights, current_key_value = layer_outputs
            if output_attentions:
                all_self_attns += (attn_weights,)
            if current_key_value is not None:
                current_key_values = current_key_values + (current_key_value,)

        hidden_states = self.output_layernorm(hidden_states)

        if output_hidden_states:
            all_hidden_states += (hidden_states,)

        return hidden_states, current_key_values, all_hidden_states, all_self_attns


# Copied from transformers.models.bert.modeling_bert.BertIntermediate with Bert->CPMAnt
class CpmAntIntermediate(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.dense = nn.Linear(config.hidden_size, config.intermediate_size)
        if isinstance(config.hidden_act, str):
            self.intermediate_act_fn = ACT2FN[config.hidden_act]
        else:
            self.intermediate_act_fn = config.hidden_act

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        hidden_states = self.dense(hidden_states)
        hidden_states = self.intermediate_act_fn(hidden_states)
        return hidden_states


class CpmAntSegmentPositionEmbedding(nn.Module):
    def __init__(self, config: CpmAntConfig):
        super().__init__()

        self.num_heads = config.num_attention_heads
        self.num_buckets = config.position_bias_num_buckets
        self.max_distance = config.position_bias_max_distance
        self.num_segments = config.segment_types

        self.relative_attention_bias = nn.Parameter(
            torch.empty(
                config.segment_types * config.segment_types + config.position_bias_num_buckets,
                config.num_attention_heads,
            )
        )

    def forward(
        self,
        key_pos: torch.Tensor,
        query_pos: torch.Tensor,
        key_segment: torch.Tensor,
        query_segment: torch.Tensor,
    ):
        with torch.no_grad():
            batch = key_pos.size(0)
            keylen = key_pos.size(1)
            querylen = query_pos.size(1)

            if key_pos.size(0) != query_pos.size(0):
                raise AssertionError(
                    f"key_pos.size(0) should be equal to query_pos.size(0), but got {key_pos.size(0)} and {query_pos.size(0)}!"
                )
            if keylen != key_segment.size(1) or querylen != query_segment.size(1):
                raise AssertionError(
                    f"keylen should be equal to key_segment.size(1), but got {keylen} and {key_segment.size(1)}!"
                )
            if querylen != query_segment.size(1):
                raise AssertionError(
                    f"querylen should be equal to query_segment.size(1), but got {querylen} and {query_segment.szie(1)}!"
                )

            key_pos = key_pos.view(batch, -1, keylen)
            query_pos = query_pos.view(batch, querylen, -1)
            key_segment = key_segment.view(batch, -1, keylen)
            query_segment = query_segment.view(batch, querylen, -1)

            relative_position_bucket = self._segment_relative_position_bucket(query_segment, key_segment)
            relative_position_bucket = relative_position_bucket + self.num_buckets

            # (batch, len_q, len_k)
            absolute_position_bucket = self._position_bucket(
                torch.arange(keylen, dtype=torch.int32, device=relative_position_bucket.device)[None, :]
                - torch.arange(querylen, dtype=torch.int32, device=relative_position_bucket.device)[:, None],
                num_buckets=self.num_buckets,
                max_distance=self.max_distance,
            )
            relative_position_bucket = torch.where(
                (key_segment == query_segment),
                absolute_position_bucket[None, :, :],
                relative_position_bucket,
            )

        # (batch, len_q, len_k, num_heads)
        embeds = F.embedding(relative_position_bucket, self.relative_attention_bias)
        # (batch, num_heads, len_q, len_k)
        embeds = embeds.permute(0, 3, 1, 2).contiguous()
        return embeds

    def _segment_relative_position_bucket(self, query_segment, key_segment):
        return query_segment * self.num_segments + key_segment

    def _position_bucket(self, relative_position, num_buckets=32, max_distance=128):
        relative_buckets = 0
        # always bidirectional in CPMAnt
        num_buckets //= 2
        relative_buckets = (relative_position > 0).to(torch.int32) * num_buckets
        relative_position = torch.abs(relative_position)
        max_exact = num_buckets // 2
        is_small = relative_position < max_exact
        relative_postion_if_large = max_exact + (
            torch.log(relative_position.float() / max_exact)
            / math.log(max_distance / max_exact)
            * (num_buckets - max_exact)
        ).to(torch.int32)
        relative_postion_if_large = torch.min(
            relative_postion_if_large,
            torch.full_like(relative_postion_if_large, num_buckets - 1),
        )
        relative_buckets += torch.where(is_small, relative_position.to(torch.int32), relative_postion_if_large)
        return relative_buckets


# Copied from transformers.models.bert.modeling_bert.BertOutput with Bert->CPMAnt
class CpmAntOutput(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.dense = nn.Linear(config.intermediate_size, config.hidden_size)
        self.LayerNorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps)
        self.dropout = nn.Dropout(config.hidden_dropout_prob)

    def forward(self, hidden_states: torch.Tensor, input_tensor: torch.Tensor) -> torch.Tensor:
        hidden_states = self.dense(hidden_states)
        hidden_states = self.dropout(hidden_states)
        hidden_states = self.LayerNorm(hidden_states + input_tensor)
        return hidden_states


class CpmAntPreTrainedModel(PreTrainedModel):
    """
    An abstract class to handle weights initialization and a simple interface for downloading and loading pretrained
    models.
    """

    config_class = CpmAntConfig
    base_model_prefix = "cpmant"

    def _init_weights(self, module):
        """Initialize the weights"""
        if isinstance(module, nn.Linear):
            module.weight.data.normal_(mean=0.0, std=self.config.init_std)
            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.init_std)
            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)
        elif isinstance(module, CpmAntLayerNorm):
            module.weight.data.fill_(1.0)
        elif isinstance(module, CpmAntSegmentPositionEmbedding):
            module.relative_attention_bias.data.normal_(mean=0.0, std=self.config.init_std)


CPMANT_START_DOCSTRING = r"""
    This model is a PyTorch [torch.nn.Module](https://pytorch.org/docs/stable/nn.html#torch.nn.Module) sub-class. Use
    it as a regular PyTorch Module and refer to the PyTorch documentation for all matter related to general usage and
    behavior.

    Parameters
        config ([`~CpmAntConfig`]): Model configuration class with all the parameters of the
            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.
"""

CPMANT_INPUTS_DOCSTRING = r"""
    Args:
        input_ids (`torch.Tensor` of shape `(batch_size, seq_len)`):
            Indices of input sequence tokens in the vocabulary.

            Indices can be obtained using [`CPMAntTokenizer`]. See [`PreTrainedTokenizer.encode`] and
            [`PreTrainedTokenizer.__call__`] for details.

            [What are input IDs?](../glossary#input-ids)
        past_key_values (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
            Contains pre-computed hidden-states (key and values in the self-attention blocks and in the cross-attention
            blocks) that can be used (see `past_key_values` input) to speed up sequential decoding.
        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.
        output_hidden_states (`bool`, *optional*):
            Whether or not to return the hidden states of all layers.
        return_dict (`bool`, *optional*):
            Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
"""


@add_start_docstrings(
    "The bare CPMAnt Model outputting raw hidden-states without any specific head on top.",
    CPMANT_START_DOCSTRING,
)
class CpmAntModel(CpmAntPreTrainedModel):
    def __init__(self, config: CpmAntConfig):
        super().__init__(config)
        self.encoder = CpmAntEncoder(config)
        self.segment_embedding = nn.Embedding(config.segment_types, config.hidden_size)
        self.input_embedding = nn.Embedding(
            config.vocab_size + config.prompt_types * config.prompt_length, config.hidden_size
        )
        self.position_bias = CpmAntSegmentPositionEmbedding(config)
        self.prompt_length = config.prompt_length
        self.vocab_size = config.vocab_size

        self.post_init()

    def get_input_embeddings(self):
        return self.input_embedding

    def set_input_embeddings(self, embeddings, **kwargs):
        self.input_embedding = embeddings

    def _prepare_attention_mask(self, input_ids, span, context, length):
        batch = input_ids.size(0)
        seqlen = input_ids.size(1)
        device = input_ids.device
        directional_mask_2d = torch.arange(seqlen, device=device) <= torch.arange(seqlen, device=device).view(-1, 1)
        attention_mask = context[:, None, :] | (
            context[:, :, None].logical_not() & directional_mask_2d.view(1, seqlen, seqlen)
        )
        attention_mask = attention_mask & (span[:, None, :] == span[:, :, None])
        # mask for left padding
        mask_1d = (
            torch.tensor(list(range(seqlen - self.prompt_length))[::-1], device=device)[None, :].repeat(batch, 1)
            < length[:, None]
        )
        mask_1d = torch.cat((torch.ones(batch, self.prompt_length, device=device).bool(), mask_1d), dim=1)
        attention_mask = mask_1d.view(batch, seqlen, 1) & mask_1d.view(batch, 1, seqlen) & attention_mask
        return attention_mask

    @add_start_docstrings_to_model_forward(CPMANT_INPUTS_DOCSTRING)
    @add_code_sample_docstrings(
        checkpoint=_CHECKPOINT_FOR_DOC,
        output_type=BaseModelOutputWithPast,
        config_class=_CONFIG_FOR_DOC,
    )
    def forward(
        self,
        input_ids: Optional[torch.Tensor] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        past_key_values: Optional[Tuple[Tuple[torch.Tensor]]] = None,
        use_cache: Optional[bool] = None,
        return_dict: Optional[bool] = None,
        **kwargs,
    ) -> Union[Tuple[torch.Tensor], BaseModelOutputWithPast]:
        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
        )
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict
        use_cache = use_cache if use_cache is not None else self.config.use_cache

        # add prompts ahead
        if input_ids.dtype != torch.int32:
            input_ids = input_ids.to(torch.int32)
        dtype, device = input_ids.dtype, input_ids.device
        segment = torch.where(input_ids != 0, 2, 0).to(dtype=dtype, device=device)
        length = (segment != 0).sum(-1).to(dtype=dtype, device=device)
        input_ids = torch.cat(
            (
                torch.arange(
                    self.prompt_length * 2 + self.vocab_size,
                    self.prompt_length * 3 + self.vocab_size,
                    dtype=dtype,
                    device=device,
                ).repeat(input_ids.size(0), 1),
                input_ids,
            ),
            dim=1,
        )
        batch, seq_length = input_ids.size()
        segment = torch.cat((torch.zeros(batch, self.prompt_length, dtype=dtype, device=device), segment), dim=1)
        context = torch.full((batch, seq_length), 1, dtype=dtype, device=device)
        position = torch.arange(seq_length, dtype=dtype, device=device).repeat(batch, 1)
        span = torch.full((batch, seq_length), 0, dtype=dtype, device=device)

        if past_key_values is None:
            past_length = 0
            past_key_values = tuple([None] * self.encoder.num_layers)
            input_ids = input_ids.contiguous()
            hidden_states = self.input_embedding(input_ids)
            segment_states = self.segment_embedding(segment)
            hidden_states = hidden_states + segment_states
        else:
            past_length = past_key_values[0][0].size(-2)
            segment_states = self.segment_embedding(segment)
            hidden_states = self.input_embedding(input_ids) + segment_states[:, -1:, :]

        attention_mask = self._prepare_attention_mask(input_ids, span, context, length)
        position_bias = self.position_bias(position, position, segment, segment)

        attention_mask = attention_mask[:, past_length:, :]
        position_bias = position_bias[:, :, past_length:, :]
        hidden_states = hidden_states[:, past_length:, :]

        hidden_states, present_key_values, all_hidden_states, all_attentions = self.encoder(
            hidden_states,
            attention_mask,
            position_bias,
            output_attentions,
            output_hidden_states,
            past_key_values,
            use_cache,
        )

        if past_length == 0:
            hidden_states = hidden_states[:, self.prompt_length :, :]
            # drop the prompt
            if all_attentions is not None:
                new_attentions = ()
                for attention in all_attentions:
                    new_attentions += (attention[:, :, self.prompt_length :, self.prompt_length :],)
                all_attentions = new_attentions
            if all_hidden_states is not None:
                new_hidden_states = ()
                for hidden_state in all_hidden_states:
                    new_hidden_states += (hidden_state[:, self.prompt_length :, :],)
                all_hidden_states = new_hidden_states

        if not return_dict:
            return tuple(
                v for v in [hidden_states, present_key_values, all_hidden_states, all_attentions] if v is not None
            )

        return BaseModelOutputWithPast(
            last_hidden_state=hidden_states,
            past_key_values=present_key_values,
            hidden_states=all_hidden_states,
            attentions=all_attentions,
        )


@add_start_docstrings(
    """
    The CPMAnt Model with a language modeling head on top (linear layer with weights tied to the input embeddings).
    """,
    CPMANT_START_DOCSTRING,
)
class CpmAntForCausalLM(CpmAntPreTrainedModel):
    _tied_weights_keys = ["lm_head.weight"]

    def __init__(self, config: CpmAntConfig):
        super().__init__(config)
        self.cpmant = CpmAntModel(config)

        # lm_head.weight is tied to cpmant.input_embedding.weight
        self.lm_head = nn.Linear(
            config.hidden_size, config.vocab_size + config.prompt_types * config.prompt_length, bias=False
        )
        self.post_init()

    @add_start_docstrings_to_model_forward(CPMANT_INPUTS_DOCSTRING)
    @add_code_sample_docstrings(
        checkpoint=_CHECKPOINT_FOR_DOC,
        output_type=CausalLMOutputWithPast,
        config_class=_CONFIG_FOR_DOC,
    )
    def forward(
        self,
        input_ids: Optional[torch.Tensor] = None,
        past_key_values: Optional[List[Tuple[torch.Tensor, torch.Tensor]]] = None,
        use_cache: Optional[bool] = None,
        output_attentions: Optional[bool] = None,
        output_hidden_states: Optional[bool] = None,
        labels: Optional[torch.Tensor] = None,
        return_dict: Optional[bool] = None,
        attention_mask: Optional[torch.Tensor] = None,  # dummy parameter for text-generation pipeline
        **kwargs,
    ) -> Union[Tuple, CausalLMOutputWithPast]:
        r"""
        Args:
            input_ids (`torch.Tensor` of shape `(batch_size, seq_len)`):
                Indices of input sequence tokens in the vocabulary.

                Indices can be obtained using [`CPMAntTokenizer`]. See [`PreTrainedTokenizer.encode`] and
                [`PreTrainedTokenizer.__call__`] for details.

                [What are input IDs?](../glossary#input-ids)
            past_key_values (`tuple(tuple(torch.FloatTensor))`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
                Contains pre-computed hidden-states (key and values in the self-attention blocks and in the
                cross-attention blocks) that can be used (see `past_key_values` input) to speed up sequential decoding.
            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.
            output_hidden_states (`bool`, *optional*):
                Whether or not to return the hidden states of all layers.
            labels (`torch.Tensor` of shape `(batch_size, sequence_length)`, *optional*):
                Labels for computing the masked language modeling loss.
            return_dict (`bool`, *optional*):
                Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
            attention_mask (`torch.Tensor` of shape `(batch_size, sequence_length)`, *optional*):
                CPMAnt will process attention mask automatically, this parameter is a dummy parameter for
                text-generation pipeline.

        Example:

        Text Generation with CpmAntForCausalLM.
        ```python
        >>> from transformers import CPMAntTokenizer, CpmAntForCausalLM

        >>> texts = "今天天气不错，"
        >>> model = CpmAntForCausalLM.from_pretrained("openbmb/cpm-ant-10b")
        >>> tokenizer = CPMAntTokenizer.from_pretrained("openbmb/cpm-ant-10b")
        >>> input_ids = tokenizer(texts, return_tensors="pt")
        >>> outputs = model.generate(**input_ids)
        >>> output_texts = tokenizer.batch_decode(outputs)
        >>> print(output_texts)
        ['今天天气不错，阳光明媚，我和妈妈一起去超市买东西。\n在超市里，我看到了一个很好玩的玩具，它的名字叫“机器人”。它有一个圆圆的脑袋，两只圆圆的眼睛，还有一个圆圆的']
        ```
        """
        return_dict = return_dict if return_dict is not None else self.config.use_return_dict

        model_output = self.cpmant(
            input_ids, output_attentions, output_hidden_states, past_key_values, use_cache, return_dict
        )
        hidden_states = model_output.last_hidden_state if return_dict else model_output[0]

        logits = self.lm_head(hidden_states)

        loss = None
        if labels is not None:
            loss_func = CrossEntropyLoss()
            loss = loss_func(logits.view(-1, logits.size(-1)), labels.view(-1))

        if not return_dict:
            output = (logits,) + model_output[1:]
            return ((loss,) + output) if loss is not None else output

        return CausalLMOutputWithPast(
            loss=loss,
            logits=logits,
            past_key_values=model_output.past_key_values,
            hidden_states=model_output.hidden_states,
            attentions=model_output.attentions,
        )

    def get_input_embeddings(self):
        return self.cpmant.input_embedding

    def set_input_embeddings(self, embeddings):
        self.cpmant.input_embedding = embeddings

    def get_output_embeddings(self):
        return self.lm_head

    def set_output_embeddings(self, new_embeddings):
        self.lm_head = new_embeddings

    def prepare_inputs_for_generation(self, input_ids, **kwargs):
        input_ids = input_ids.int()
        # save the memory usage of dummy attention mask
        if "attention_mask" in kwargs:
            kwargs["attention_mask"] = torch.zeros(1, 1)

        return {
            "input_ids": input_ids,
            "use_cache": kwargs["use_cache"],
            "past_key_values": kwargs.get("past_key_values", None),
        }

    def _reorder_cache(self, past_key_values, beam_idx):
        past_key_values = [list(each) if each is not None else each for each in past_key_values]
        for key_value_layer in past_key_values:
            key_value_layer[0] = key_value_layer[0][beam_idx]
            key_value_layer[1] = key_value_layer[1][beam_idx]
        return past_key_values