diff --git "a/llmeval-env/lib/python3.10/site-packages/transformers/models/big_bird/modeling_big_bird.py" "b/llmeval-env/lib/python3.10/site-packages/transformers/models/big_bird/modeling_big_bird.py" new file mode 100644--- /dev/null +++ "b/llmeval-env/lib/python3.10/site-packages/transformers/models/big_bird/modeling_big_bird.py" @@ -0,0 +1,3149 @@ +# coding=utf-8 +# Copyright 2021 Google Research 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 BigBird model.""" + + +import math +import os +from dataclasses import dataclass +from typing import Optional, Tuple, Union + +import numpy as np +import torch +import torch.utils.checkpoint +from torch import nn +from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss, MSELoss + +from ...activations import ACT2FN +from ...modeling_outputs import ( + BaseModelOutputWithPastAndCrossAttentions, + BaseModelOutputWithPoolingAndCrossAttentions, + CausalLMOutputWithCrossAttentions, + MaskedLMOutput, + MultipleChoiceModelOutput, + SequenceClassifierOutput, + TokenClassifierOutput, +) +from ...modeling_utils import PreTrainedModel +from ...pytorch_utils import apply_chunking_to_forward +from ...utils import ( + ModelOutput, + add_code_sample_docstrings, + add_start_docstrings, + add_start_docstrings_to_model_forward, + logging, + replace_return_docstrings, +) +from .configuration_big_bird import BigBirdConfig + + +logger = logging.get_logger(__name__) + +_CHECKPOINT_FOR_DOC = "google/bigbird-roberta-base" +_CONFIG_FOR_DOC = "BigBirdConfig" + + +from ..deprecated._archive_maps import BIG_BIRD_PRETRAINED_MODEL_ARCHIVE_LIST # noqa: F401, E402 + + +_TRIVIA_QA_MAPPING = { + "big_bird_attention": "attention/self", + "output_layer_norm": "output/LayerNorm", + "attention_output": "attention/output/dense", + "output": "output/dense", + "self_attention_layer_norm": "attention/output/LayerNorm", + "intermediate": "intermediate/dense", + "word_embeddings": "bert/embeddings/word_embeddings", + "position_embedding": "bert/embeddings/position_embeddings", + "type_embeddings": "bert/embeddings/token_type_embeddings", + "embeddings": "bert/embeddings", + "layer_normalization": "output/LayerNorm", + "layer_norm": "LayerNorm", + "trivia_qa_head": "qa_classifier", + "dense": "intermediate/dense", + "dense_1": "qa_outputs", +} + + +def load_tf_weights_in_big_bird(model, tf_checkpoint_path, is_trivia_qa=False): + """Load tf checkpoints in a pytorch model.""" + + def load_tf_weights_bert(init_vars, tf_path): + names = [] + tf_weights = {} + + for name, shape in init_vars: + array = tf.train.load_variable(tf_path, name) + name = name.replace("bert/encoder/LayerNorm", "bert/embeddings/LayerNorm") + logger.info(f"Loading TF weight {name} with shape {shape}") + names.append(name) + tf_weights[name] = array + + return names, tf_weights + + def load_tf_weights_trivia_qa(init_vars): + names = [] + tf_weights = {} + + for i, var in enumerate(init_vars): + name_items = var.name.split("/") + + if "transformer_scaffold" in name_items[0]: + layer_name_items = name_items[0].split("_") + if len(layer_name_items) < 3: + layer_name_items += [0] + + name_items[0] = f"bert/encoder/layer_{layer_name_items[2]}" + + name = "/".join([_TRIVIA_QA_MAPPING[x] if x in _TRIVIA_QA_MAPPING else x for x in name_items])[ + :-2 + ] # remove last :0 in variable + + if "self/attention/output" in name: + name = name.replace("self/attention/output", "output") + + if i >= len(init_vars) - 2: + name = name.replace("intermediate", "output") + + logger.info(f"Loading TF weight {name} with shape {var.shape}") + array = var.value().numpy() + names.append(name) + tf_weights[name] = array + + return names, tf_weights + + try: + import re + + import numpy as np + import tensorflow as tf + except ImportError: + logger.error( + "Loading a TensorFlow model in PyTorch, requires TensorFlow to be installed. Please see " + "https://www.tensorflow.org/install/ for installation instructions." + ) + raise + tf_path = os.path.abspath(tf_checkpoint_path) + logger.info(f"Converting TensorFlow checkpoint from {tf_path}") + + # Load weights from TF model + init_vars = tf.saved_model.load(tf_path).variables if is_trivia_qa else tf.train.list_variables(tf_path) + + if len(init_vars) <= 0: + raise ValueError("Loaded trained variables cannot be empty.") + + pt_names = list(model.state_dict().keys()) + + if is_trivia_qa: + names, tf_weights = load_tf_weights_trivia_qa(init_vars) + else: + names, tf_weights = load_tf_weights_bert(init_vars, tf_path) + + for txt_name in names: + array = tf_weights[txt_name] + name = txt_name.split("/") + # adam_v and adam_m are variables used in AdamWeightDecayOptimizer to calculated m and v + # which are not required for using pretrained model + if any( + n in ["adam_v", "adam_m", "AdamWeightDecayOptimizer", "AdamWeightDecayOptimizer_1", "global_step"] + for n in name + ): + logger.info(f"Skipping {'/'.join(name)}") + continue + pointer = model + pt_name = [] + for m_name in name: + if re.fullmatch(r"[A-Za-z]+_\d+", m_name): + scope_names = re.split(r"_(\d+)", m_name) + else: + scope_names = [m_name] + if scope_names[0] == "kernel" or scope_names[0] == "gamma": + pointer = getattr(pointer, "weight") + pt_name.append("weight") + elif scope_names[0] == "output_bias" or scope_names[0] == "beta": + pointer = getattr(pointer, "bias") + pt_name.append("bias") + elif scope_names[0] == "output_weights": + pointer = getattr(pointer, "weight") + pt_name.append("weight") + elif scope_names[0] == "squad": + pointer = getattr(pointer, "classifier") + pt_name.append("classifier") + elif scope_names[0] == "transform": + pointer = getattr(pointer, "transform") + pt_name.append("transform") + if ("bias" in name) or ("kernel" in name): + pointer = getattr(pointer, "dense") + pt_name.append("dense") + elif ("beta" in name) or ("gamma" in name): + pointer = getattr(pointer, "LayerNorm") + pt_name.append("LayerNorm") + else: + try: + pointer = getattr(pointer, scope_names[0]) + pt_name.append(f"{scope_names[0]}") + except AttributeError: + logger.info(f"Skipping {m_name}") + continue + if len(scope_names) >= 2: + num = int(scope_names[1]) + pointer = pointer[num] + pt_name.append(f"{num}") + if m_name[-11:] == "_embeddings" or m_name == "embeddings": + pointer = getattr(pointer, "weight") + pt_name.append("weight") + elif m_name == "kernel": + array = np.transpose(array) + try: + if len(array.shape) > len(pointer.shape) and math.prod(array.shape) == math.prod(pointer.shape): + # print(txt_name, array.shape) + if ( + txt_name.endswith("attention/self/key/kernel") + or txt_name.endswith("attention/self/query/kernel") + or txt_name.endswith("attention/self/value/kernel") + ): + array = array.transpose(1, 0, 2).reshape(pointer.shape) + elif txt_name.endswith("attention/output/dense/kernel"): + array = array.transpose(0, 2, 1).reshape(pointer.shape) + else: + array = array.reshape(pointer.shape) + + if pointer.shape != array.shape: + raise ValueError( + f"Pointer shape {pointer.shape} and array shape {array.shape} mismatched of {txt_name}." + ) + except ValueError as e: + e.args += (pointer.shape, array.shape) + raise + pt_weight_name = ".".join(pt_name) + logger.info(f"Initialize PyTorch weight {pt_weight_name} from {txt_name}.") + pointer.data = torch.from_numpy(array) + tf_weights.pop(txt_name, None) + pt_names.remove(pt_weight_name) + + logger.info(f"Weights not copied to PyTorch model: {', '.join(tf_weights.keys())}.") + logger.info(f"Weights not initialized in PyTorch model: {', '.join(pt_names)}.") + return model + + +class BigBirdEmbeddings(nn.Module): + """Construct the embeddings from word, position and token_type embeddings.""" + + # Copied from transformers.models.bert.modeling_bert.BertEmbeddings.__init__ + def __init__(self, config): + super().__init__() + self.word_embeddings = nn.Embedding(config.vocab_size, config.hidden_size, padding_idx=config.pad_token_id) + self.position_embeddings = nn.Embedding(config.max_position_embeddings, config.hidden_size) + self.token_type_embeddings = nn.Embedding(config.type_vocab_size, config.hidden_size) + + # self.LayerNorm is not snake-cased to stick with TensorFlow model variable name and be able to load + # any TensorFlow checkpoint file + self.LayerNorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps) + self.dropout = nn.Dropout(config.hidden_dropout_prob) + # position_ids (1, len position emb) is contiguous in memory and exported when serialized + self.position_embedding_type = getattr(config, "position_embedding_type", "absolute") + self.register_buffer( + "position_ids", torch.arange(config.max_position_embeddings).expand((1, -1)), persistent=False + ) + self.register_buffer( + "token_type_ids", torch.zeros(self.position_ids.size(), dtype=torch.long), persistent=False + ) + # End copy + + self.rescale_embeddings = config.rescale_embeddings + self.hidden_size = config.hidden_size + + def forward( + self, input_ids=None, token_type_ids=None, position_ids=None, inputs_embeds=None, past_key_values_length=0 + ): + if input_ids is not None: + input_shape = input_ids.size() + else: + input_shape = inputs_embeds.size()[:-1] + + seq_length = input_shape[1] + + if position_ids is None: + position_ids = self.position_ids[:, past_key_values_length : seq_length + past_key_values_length] + + # Setting the token_type_ids to the registered buffer in constructor where it is all zeros, which usually occurs + # when its auto-generated, registered buffer helps users when tracing the model without passing token_type_ids, solves + # issue #5664 + if token_type_ids is None: + if hasattr(self, "token_type_ids"): + buffered_token_type_ids = self.token_type_ids[:, :seq_length] + buffered_token_type_ids_expanded = buffered_token_type_ids.expand(input_shape[0], seq_length) + token_type_ids = buffered_token_type_ids_expanded + else: + token_type_ids = torch.zeros(input_shape, dtype=torch.long, device=self.position_ids.device) + + if inputs_embeds is None: + inputs_embeds = self.word_embeddings(input_ids) + + if self.rescale_embeddings: + inputs_embeds = inputs_embeds * (self.hidden_size**0.5) + + token_type_embeddings = self.token_type_embeddings(token_type_ids) + + embeddings = inputs_embeds + token_type_embeddings + + position_embeddings = self.position_embeddings(position_ids) + embeddings += position_embeddings + + embeddings = self.dropout(embeddings) + embeddings = self.LayerNorm(embeddings) + return embeddings + + +class BigBirdSelfAttention(nn.Module): + def __init__(self, config): + super().__init__() + if config.hidden_size % config.num_attention_heads != 0 and not hasattr(config, "embedding_size"): + raise ValueError( + f"The hidden size ({config.hidden_size}) is not a multiple of the number of attention " + f"heads ({config.num_attention_heads})" + ) + + self.num_attention_heads = config.num_attention_heads + self.attention_head_size = int(config.hidden_size / config.num_attention_heads) + self.all_head_size = self.num_attention_heads * self.attention_head_size + + self.query = nn.Linear(config.hidden_size, self.all_head_size, bias=config.use_bias) + self.key = nn.Linear(config.hidden_size, self.all_head_size, bias=config.use_bias) + self.value = nn.Linear(config.hidden_size, self.all_head_size, bias=config.use_bias) + + self.dropout = nn.Dropout(config.attention_probs_dropout_prob) + self.is_decoder = config.is_decoder + + def transpose_for_scores(self, x): + new_x_shape = x.size()[:-1] + (self.num_attention_heads, self.attention_head_size) + x = x.view(*new_x_shape) + return x.permute(0, 2, 1, 3) + + def forward( + self, + hidden_states, + attention_mask=None, + head_mask=None, + encoder_hidden_states=None, + encoder_attention_mask=None, + past_key_value=None, + output_attentions=False, + ): + mixed_query_layer = self.query(hidden_states) + + # If this is instantiated as a cross-attention module, the keys + # and values come from an encoder; the attention mask needs to be + # such that the encoder's padding tokens are not attended to. + is_cross_attention = encoder_hidden_states is not None + + if is_cross_attention and past_key_value is not None: + # reuse k,v, cross_attentions + key_layer = past_key_value[0] + value_layer = past_key_value[1] + attention_mask = encoder_attention_mask + elif is_cross_attention: + key_layer = self.transpose_for_scores(self.key(encoder_hidden_states)) + value_layer = self.transpose_for_scores(self.value(encoder_hidden_states)) + attention_mask = encoder_attention_mask + elif past_key_value is not None: + key_layer = self.transpose_for_scores(self.key(hidden_states)) + value_layer = self.transpose_for_scores(self.value(hidden_states)) + key_layer = torch.cat([past_key_value[0], key_layer], dim=2) + value_layer = torch.cat([past_key_value[1], value_layer], dim=2) + else: + key_layer = self.transpose_for_scores(self.key(hidden_states)) + value_layer = self.transpose_for_scores(self.value(hidden_states)) + + query_layer = self.transpose_for_scores(mixed_query_layer) + + if self.is_decoder: + # if cross_attention save Tuple(torch.Tensor, torch.Tensor) of all cross attention key/value_states. + # Further calls to cross_attention layer can then reuse all cross-attention + # key/value_states (first "if" case) + # if uni-directional self-attention (decoder) save Tuple(torch.Tensor, torch.Tensor) of + # all previous decoder key/value_states. Further calls to uni-directional self-attention + # can concat previous decoder key/value_states to current projected key/value_states (third "elif" case) + # if encoder bi-directional self-attention `past_key_value` is always `None` + past_key_value = (key_layer, value_layer) + + # Take the dot product between "query" and "key" to get the raw attention scores. + attention_scores = torch.matmul(query_layer, key_layer.transpose(-1, -2)) + + attention_scores = attention_scores / math.sqrt(self.attention_head_size) + if attention_mask is not None: + # Apply the attention mask is (precomputed for all layers in BigBirdModel forward() function) + attention_scores = attention_scores + attention_mask + + # Normalize the attention scores to probabilities. + attention_probs = nn.functional.softmax(attention_scores, dim=-1) + + # This is actually dropping out entire tokens to attend to, which might + # seem a bit unusual, but is taken from the original Transformer paper. + attention_probs = self.dropout(attention_probs) + + # Mask heads if we want to + if head_mask is not None: + attention_probs = attention_probs * head_mask + + context_layer = torch.matmul(attention_probs, value_layer) + + context_layer = context_layer.permute(0, 2, 1, 3).contiguous() + new_context_layer_shape = context_layer.size()[:-2] + (self.all_head_size,) + context_layer = context_layer.view(*new_context_layer_shape) + + outputs = (context_layer, attention_probs) if output_attentions else (context_layer,) + + if self.is_decoder: + outputs = outputs + (past_key_value,) + return outputs + + +class BigBirdBlockSparseAttention(nn.Module): + def __init__(self, config, seed=None): + super().__init__() + + self.max_seqlen = config.max_position_embeddings + self.seed = seed + + if config.hidden_size % config.num_attention_heads != 0: + raise ValueError( + f"The hidden size {config.hidden_size} is not a multiple of the number of attention " + f"heads {config.num_attention_heads}." + ) + + self.num_attention_heads = config.num_attention_heads + self.num_random_blocks = config.num_random_blocks + self.block_size = config.block_size + + self.attention_head_size = int(config.hidden_size / config.num_attention_heads) + self.all_head_size = self.num_attention_heads * self.attention_head_size + + self.query = nn.Linear(config.hidden_size, self.all_head_size, bias=config.use_bias) + self.key = nn.Linear(config.hidden_size, self.all_head_size, bias=config.use_bias) + self.value = nn.Linear(config.hidden_size, self.all_head_size, bias=config.use_bias) + + def transpose_for_scores(self, x): + new_x_shape = x.size()[:-1] + (self.num_attention_heads, self.attention_head_size) + x = x.view(*new_x_shape) + return x.permute(0, 2, 1, 3) + + def forward( + self, + hidden_states, + band_mask=None, + from_mask=None, + to_mask=None, + from_blocked_mask=None, + to_blocked_mask=None, + output_attentions=None, + ): + # Currently this `class` can't be used in decoder. + + batch_size, seqlen, _ = hidden_states.size() + to_seq_length = from_seq_length = seqlen + from_block_size = to_block_size = self.block_size + + if from_seq_length % from_block_size != 0: + raise ValueError("Query sided sequence length must be multiple of block size") + + if to_seq_length % to_block_size != 0: + raise ValueError("Key/Value sided sequence length must be multiple of block size") + + query_layer = self.transpose_for_scores(self.query(hidden_states)) + key_layer = self.transpose_for_scores(self.key(hidden_states)) + value_layer = self.transpose_for_scores(self.value(hidden_states)) + + context_layer, attention_probs = self.bigbird_block_sparse_attention( + query_layer, + key_layer, + value_layer, + band_mask, + from_mask, + to_mask, + from_blocked_mask, + to_blocked_mask, + self.num_attention_heads, + self.num_random_blocks, + self.attention_head_size, + from_block_size, + to_block_size, + batch_size, + from_seq_length, + to_seq_length, + seed=self.seed, + plan_from_length=None, + plan_num_rand_blocks=None, + output_attentions=output_attentions, + ) + + context_layer = context_layer.contiguous().view(batch_size, from_seq_length, -1) + + outputs = (context_layer, attention_probs) if output_attentions else (context_layer,) + return outputs + + @staticmethod + def torch_bmm_nd(inp_1, inp_2, ndim=None): + """Fast nd matrix multiplication""" + # faster replacement of torch.einsum ("bhqk,bhkd->bhqd") + return torch.bmm(inp_1.reshape((-1,) + inp_1.shape[-2:]), inp_2.reshape((-1,) + inp_2.shape[-2:])).view( + inp_1.shape[: ndim - 2] + (inp_1.shape[ndim - 2], inp_2.shape[ndim - 1]) + ) + + @staticmethod + def torch_bmm_nd_transpose(inp_1, inp_2, ndim=None): + """Fast nd matrix multiplication with transpose""" + # faster replacement of torch.einsum (bhqd,bhkd->bhqk) + return torch.bmm( + inp_1.reshape((-1,) + inp_1.shape[-2:]), inp_2.reshape((-1,) + inp_2.shape[-2:]).transpose(1, 2) + ).view(inp_1.shape[: ndim - 2] + (inp_1.shape[ndim - 2], inp_2.shape[ndim - 2])) + + def bigbird_block_sparse_attention( + self, + query_layer, + key_layer, + value_layer, + band_mask, + from_mask, + to_mask, + from_blocked_mask, + to_blocked_mask, + n_heads, + n_rand_blocks, + attention_head_size, + from_block_size, + to_block_size, + batch_size, + from_seq_len, + to_seq_len, + seed, + plan_from_length, + plan_num_rand_blocks, + output_attentions, + ): + # BigBird block-sparse attention as suggested in paper + + # ITC: + # global tokens: 2 x block_size + # window tokens: 3 x block_size + # random tokens: num_rand_tokens x block_size + + # ETC: + # global tokens: extra_globals_tokens + 2 x block_size + # window tokens: 3 x block_size + # random tokens: num_rand_tokens x block_size + + # Note: + # 1) Currently, ETC is not supported. + # 2) Window size is fixed to 3 blocks & it can be changed only by + # changing `block_size`. + # 3) Number of global blocks are fixed (2 blocks here) & global tokens can be + # controlled only by `block_size`. + + # attention is calculated separately for q[0], q[1], q[2:-2], q[-2], q[-1] in order to use special trick of shifting tokens (for calculating sliding attention) + # hence following code can be divided into 5 parts. + + if from_seq_len // from_block_size != to_seq_len // to_block_size: + raise ValueError("Error the number of blocks needs to be same!") + + rsqrt_d = 1 / math.sqrt(attention_head_size) + bsz = batch_size + attn_mask_penalty = -10000.0 + + # generate random attention and corresponding masks + np.random.seed(seed) + if from_seq_len in [1024, 3072, 4096]: # old plans used in paper + rand_attn = [ + self._bigbird_block_rand_mask( + self.max_seqlen, self.max_seqlen, from_block_size, to_block_size, n_rand_blocks, last_idx=1024 + )[: (from_seq_len // from_block_size - 2)] + for _ in range(n_heads) + ] + else: + if plan_from_length is None: + plan_from_length, plan_num_rand_blocks = self._get_rand_attn_plan( + from_seq_len, from_block_size, n_rand_blocks + ) + + rand_attn = self._bigbird_block_rand_mask_with_head( + from_seq_length=from_seq_len, + to_seq_length=to_seq_len, + from_block_size=from_block_size, + to_block_size=to_block_size, + num_heads=n_heads, + plan_from_length=plan_from_length, + plan_num_rand_blocks=plan_num_rand_blocks, + ) + + rand_attn = np.stack(rand_attn, axis=0) + rand_attn = torch.tensor(rand_attn, device=query_layer.device, dtype=torch.long) + rand_attn.unsqueeze_(0) + rand_attn = torch.cat([rand_attn for _ in range(batch_size)], dim=0) + + rand_mask = self._create_rand_mask_from_inputs( + from_blocked_mask, to_blocked_mask, rand_attn, n_heads, n_rand_blocks, bsz, from_seq_len, from_block_size + ) + + blocked_query_matrix = query_layer.view(bsz, n_heads, from_seq_len // from_block_size, from_block_size, -1) + blocked_key_matrix = key_layer.view(bsz, n_heads, to_seq_len // to_block_size, to_block_size, -1) + blocked_value_matrix = value_layer.view(bsz, n_heads, to_seq_len // to_block_size, to_block_size, -1) + + # preparing block for randn attn + gathered_key = self.torch_gather_b2(blocked_key_matrix, rand_attn) + gathered_key = gathered_key.view( + bsz, n_heads, to_seq_len // to_block_size - 2, n_rand_blocks * to_block_size, -1 + ) # [bsz, n_heads, to_seq_len//to_block_size-2, n_rand_blocks, to_block_size, -1] + gathered_value = self.torch_gather_b2(blocked_value_matrix, rand_attn) + gathered_value = gathered_value.view( + bsz, n_heads, to_seq_len // to_block_size - 2, n_rand_blocks * to_block_size, -1 + ) # [bsz, n_heads, to_seq_len//to_block_size-2, n_rand_blocks, to_block_size, -1] + + # 1st PART + # 1st block (global block) attention scores + # q[0] x (k[0], k[1], k[2], k[3], k[4] .... ) + + # [bsz, n_heads, from_block_size, -1] x [bsz, n_heads, to_seq_len, -1] ==> [bsz, n_heads, from_block_size, to_seq_len] + first_product = self.torch_bmm_nd_transpose(blocked_query_matrix[:, :, 0], key_layer, ndim=4) + + first_product = first_product * rsqrt_d + first_product += (1.0 - to_mask) * attn_mask_penalty + first_attn_weights = nn.functional.softmax( + first_product, dim=-1 + ) # [bsz, n_heads, from_block_size, to_seq_len] + + # [bsz, n_heads, from_block_size, to_seq_len] x [bsz, n_heads, to_seq_len, -1] ==> [bsz, n_heads, from_block_size, -1] + first_context_layer = self.torch_bmm_nd(first_attn_weights, value_layer, ndim=4) + first_context_layer.unsqueeze_(2) + + # 2nd PART + # 2nd block attention scores + # q[1] x (sliding_keys, random_keys, global_keys) + # sliding key blocks -> 2nd, 3rd blocks + # global key blocks -> 1st block + + second_key_mat = torch.cat( + [ + blocked_key_matrix[:, :, 0], + blocked_key_matrix[:, :, 1], + blocked_key_matrix[:, :, 2], + blocked_key_matrix[:, :, -1], + gathered_key[:, :, 0], + ], + dim=2, + ) # [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1] + second_value_mat = torch.cat( + [ + blocked_value_matrix[:, :, 0], + blocked_value_matrix[:, :, 1], + blocked_value_matrix[:, :, 2], + blocked_value_matrix[:, :, -1], + gathered_value[:, :, 0], + ], + dim=2, + ) # [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1] + + # [bsz, n_heads, from_block_size, -1] x [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1] ==> [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size] + second_product = self.torch_bmm_nd_transpose(blocked_query_matrix[:, :, 1], second_key_mat, ndim=4) + second_seq_pad = torch.cat( + [ + to_mask[:, :, :, : 3 * to_block_size], + to_mask[:, :, :, -to_block_size:], + to_mask.new_ones([bsz, 1, 1, n_rand_blocks * to_block_size]), + ], + dim=3, + ) + second_rand_pad = torch.cat( + [ + rand_mask.new_ones([bsz, n_heads, from_block_size, 4 * to_block_size]), + rand_mask[:, :, 0], + ], + dim=3, + ) + second_product = second_product * rsqrt_d + second_product += (1.0 - torch.minimum(second_seq_pad, second_rand_pad)) * attn_mask_penalty + second_attn_weights = nn.functional.softmax( + second_product, dim=-1 + ) # [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size] + + # [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size] x [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1] ==> [bsz, n_heads, from_block_size, -1] + second_context_layer = self.torch_bmm_nd(second_attn_weights, second_value_mat, ndim=4) + + second_context_layer.unsqueeze_(2) + + # 3rd PART + # Middle blocks attention scores + # q[-2:2] x (sliding_keys, random_keys, global_keys) + # sliding attn is calculated using special trick of shifting tokens as discussed in paper + # random keys are generated by taking random indices as per `rand_attn` + # global keys -> 1st & last block + + exp_blocked_key_matrix = torch.cat( + [blocked_key_matrix[:, :, 1:-3], blocked_key_matrix[:, :, 2:-2], blocked_key_matrix[:, :, 3:-1]], dim=3 + ) # [bsz, n_heads, from_seq_len//from_block_size-4, 3*to_block_size, -1] + exp_blocked_value_matrix = torch.cat( + [blocked_value_matrix[:, :, 1:-3], blocked_value_matrix[:, :, 2:-2], blocked_value_matrix[:, :, 3:-1]], + dim=3, + ) # [bsz, n_heads, from_seq_len//from_block_size-4, 3*to_block_size, -1] + middle_query_matrix = blocked_query_matrix[:, :, 2:-2] + + # sliding attention scores for q[-2:2] + # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] x [b, n_heads, from_seq_len//from_block_size-4, 3*to_block_size, -1] + inner_band_product = self.torch_bmm_nd_transpose(middle_query_matrix, exp_blocked_key_matrix, ndim=5) + # ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, 3*to_block_size] + inner_band_product = inner_band_product * rsqrt_d + + # randn attention scores for q[-2:2] + # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] x [bsz, n_heads, from_seq_len//from_block_size-4, n_rand_blocks*to_block_size, -1] + rand_band_product = self.torch_bmm_nd_transpose(middle_query_matrix, gathered_key[:, :, 1:-1], ndim=5) + # ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, n_rand_blocks*to_block_size] + rand_band_product = rand_band_product * rsqrt_d + + # Including 1st block (since it's global) + first_band_product = torch.einsum( + "bhlqd,bhkd->bhlqk", middle_query_matrix, blocked_key_matrix[:, :, 0] + ) # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] x [bsz, n_heads, to_block_size, -1] ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, to_block_size] + first_band_product = first_band_product * rsqrt_d + + # Including last block (since it's global) + last_band_product = torch.einsum( + "bhlqd,bhkd->bhlqk", middle_query_matrix, blocked_key_matrix[:, :, -1] + ) # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] x [bsz, n_heads, to_block_size, -1] ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, to_block_size] + last_band_product = last_band_product * rsqrt_d + + # masking padded tokens + inner_band_product += (1.0 - band_mask) * attn_mask_penalty + first_band_product += (1.0 - to_mask[:, :, :, :to_block_size].unsqueeze(3)) * attn_mask_penalty + last_band_product += (1.0 - to_mask[:, :, :, -to_block_size:].unsqueeze(3)) * attn_mask_penalty + rand_band_product += (1.0 - rand_mask[:, :, 1:-1]) * attn_mask_penalty + + # completing attention scores matrix for all q[-2:2] + band_product = torch.cat( + [first_band_product, inner_band_product, rand_band_product, last_band_product], dim=-1 + ) # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, (5+n_rand_blocks)*to_block_size] + + # safely doing softmax since attention matrix is completed + attn_weights = nn.functional.softmax( + band_product, dim=-1 + ) # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, (5+n_rand_blocks)*to_block_size] + + # contribution of sliding keys + # [bsz, n_heads, m//from_block_size-4, from_block_size, 3*to_block_size] x [bsz, n_heads, from_seq_len//from_block_size-4, 3*to_block_size, -1] + context_layer = self.torch_bmm_nd( + attn_weights[:, :, :, :, to_block_size : 4 * to_block_size], exp_blocked_value_matrix, ndim=5 + ) + # ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] + + # adding contribution of random keys + # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, n_rand_blocks*to_block_size] x [bsz, n_heads, from_seq_len//from_block_size-4, n_rand_blocks*to_block_size, -1] + context_layer += self.torch_bmm_nd( + attn_weights[:, :, :, :, 4 * to_block_size : -to_block_size], gathered_value[:, :, 1:-1], ndim=5 + ) + # ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] + + # adding contribution of global keys + context_layer += torch.einsum( + "bhlqk,bhkd->bhlqd", attn_weights[:, :, :, :, :to_block_size], blocked_value_matrix[:, :, 0] + ) # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, to_block_size] x [bsz, n_heads, to_block_size, -1] ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] + context_layer += torch.einsum( + "bhlqk,bhkd->bhlqd", attn_weights[:, :, :, :, -to_block_size:], blocked_value_matrix[:, :, -1] + ) # [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, to_block_size] x [bsz, n_heads, to_block_size, -1] ==> [bsz, n_heads, from_seq_len//from_block_size-4, from_block_size, -1] + + # 4th PART + # last 2nd token attention scores + # q[-2] x (sliding_keys, random_keys, global_keys) + # sliding key blocks -> last 3 blocks + # global key block -> 1st block + # random key block -> based on indices stored in `randn_attn` + + second_last_key_mat = torch.cat( + [ + blocked_key_matrix[:, :, 0], + blocked_key_matrix[:, :, -3], + blocked_key_matrix[:, :, -2], + blocked_key_matrix[:, :, -1], + gathered_key[:, :, -1], + ], + dim=2, + ) # [bsz, n_heads, (4+n_random_blocks)*to_block_size, -1] + second_last_value_mat = torch.cat( + [ + blocked_value_matrix[:, :, 0], + blocked_value_matrix[:, :, -3], + blocked_value_matrix[:, :, -2], + blocked_value_matrix[:, :, -1], + gathered_value[:, :, -1], + ], + dim=2, + ) # [bsz, n_heads, (4+r)*to_block_size, -1] + + # [bsz, n_heads, from_block_size, -1] x [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1] ==> [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size] + second_last_product = self.torch_bmm_nd_transpose(blocked_query_matrix[:, :, -2], second_last_key_mat, ndim=4) + second_last_seq_pad = torch.cat( + [ + to_mask[:, :, :, :to_block_size], + to_mask[:, :, :, -3 * to_block_size :], + to_mask.new_ones([bsz, 1, 1, n_rand_blocks * to_block_size]), + ], + dim=3, + ) + second_last_rand_pad = torch.cat( + [ + rand_mask.new_ones([bsz, n_heads, from_block_size, 4 * to_block_size]), + rand_mask[:, :, -1], + ], + dim=3, + ) + second_last_product = second_last_product * rsqrt_d + second_last_product += (1.0 - torch.minimum(second_last_seq_pad, second_last_rand_pad)) * attn_mask_penalty + second_last_attn_weights = nn.functional.softmax( + second_last_product, dim=-1 + ) # [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size] + + # [bsz, n_heads, from_block_size, (4+n_rand_blocks)*to_block_size] x [bsz, n_heads, (4+n_rand_blocks)*to_block_size, -1] ==> [bsz, n_heads, from_block_size, -1] + second_last_context_layer = self.torch_bmm_nd(second_last_attn_weights, second_last_value_mat, ndim=4) + second_last_context_layer.unsqueeze_(2) + + # 5th PART + # last block (global) attention scores + # q[-1] x (k[0], k[1], k[2], k[3], .... ) + + # [bsz, n_heads, from_block_size, -1] x [bsz, n_heads, to_seq_len, -1] ==> [bsz, n_heads, from_block_size, to_seq_len] + last_product = self.torch_bmm_nd_transpose(blocked_query_matrix[:, :, -1], key_layer, ndim=4) + last_product = last_product * rsqrt_d + last_product += (1.0 - to_mask) * attn_mask_penalty + last_attn_weights = nn.functional.softmax(last_product, dim=-1) # [bsz, n_heads, from_block_size, n] + + # [bsz, n_heads, from_block_size, to_seq_len] x [bsz, n_heads, to_seq_len, -1] ==> [bsz, n_heads, from_block_size, -1] + last_context_layer = self.torch_bmm_nd(last_attn_weights, value_layer, ndim=4) + last_context_layer.unsqueeze_(2) + + # combining representations of all tokens + context_layer = torch.cat( + [first_context_layer, second_context_layer, context_layer, second_last_context_layer, last_context_layer], + dim=2, + ) + context_layer = context_layer.view((bsz, n_heads, from_seq_len, -1)) * from_mask + context_layer = torch.transpose(context_layer, 1, 2) + + # this is just for visualizing; forward pass doesn't depend on following code + if output_attentions: + # TODO(PVP): need to verify if below code is correct + attention_probs = torch.zeros( + bsz, n_heads, from_seq_len, to_seq_len, dtype=torch.float, device=context_layer.device + ) + + # 1st query block + # corresponding to `first_context_layer` + attention_probs[:, :, :from_block_size, :] = first_attn_weights # all keys global + + # 2nd query block + # corresponding to `second_context_layer` + attention_probs[:, :, from_block_size : 2 * from_block_size, : 3 * to_block_size] = second_attn_weights[ + :, :, :, : 3 * to_block_size + ] # 1st three key blocks (global + sliding) + attention_probs[:, :, from_block_size : 2 * from_block_size, -to_block_size:] = second_attn_weights[ + :, :, :, 3 * to_block_size : 4 * to_block_size + ] # last key block (global) + # random keys + for p1, i1, w1 in zip(range(bsz), rand_attn, second_attn_weights): + # p1, i1, w1 corresponds to batch_dim i.e. following operation is done for each sequence in batch + for p2, i2, w2 in zip(range(n_heads), i1, w1): + # p2, i2, w2 corresponds to head_dim i.e. following operation is done for each heads + attn_probs_view = attention_probs.view( + bsz, + n_heads, + from_seq_len // from_block_size, + from_block_size, + to_seq_len // to_block_size, + to_block_size, + ) + right_slice = w2[:, 4 * to_block_size :] + attn_probs_view[p1, p2, 1, :, i2[0]] = right_slice.view( + from_block_size, n_rand_blocks, to_block_size + ) + + # Middle query blocks + # corresponding to `context_layer` + # sliding keys + for q_idx in range(from_seq_len // from_block_size - 4): + attn_probs_view = attention_probs.view( + bsz, + n_heads, + from_seq_len // from_block_size, + from_block_size, + to_seq_len // to_block_size, + to_block_size, + )[:, :, 2:-2, :, 1:-1, :] + right_slice = attn_weights[:, :, q_idx, :, to_block_size : 4 * to_block_size] + attn_probs_view[:, :, q_idx, :, q_idx : q_idx + 3, :] = right_slice.view( + bsz, n_heads, from_block_size, 3, to_block_size + ) # inner_band_product + # global keys (corresponding to 1st key block) + attention_probs[:, :, 2 * from_block_size : -2 * from_block_size, :to_block_size] = attn_weights[ + :, :, :, :, :to_block_size + ].view(bsz, n_heads, -1, to_block_size) # first_band_product + # global keys (corresponding to last key block) + attention_probs[:, :, 2 * from_block_size : -2 * from_block_size, -to_block_size:] = attn_weights[ + :, :, :, :, -to_block_size: + ].view(bsz, n_heads, -1, to_block_size) # last_band_product + # random keys + for p1, i1, w1 in zip(range(bsz), rand_attn, attn_weights): + # p1, i1, w1 corresponds to batch_dim i.e. following operation is done for each sequence in batch + for p2, i2, w2 in zip(range(n_heads), i1, w1): + # p2, i2, w2 corresponds to head_dim i.e. following operation is done for each heads + for q_idx in range(1, len(i2) - 1): + attn_probs_view = attention_probs.view( + bsz, + n_heads, + from_seq_len // from_block_size, + from_block_size, + to_seq_len // to_block_size, + to_block_size, + ) + right_slice = w2[q_idx - 1, :, 4 * to_block_size : -to_block_size] + attn_probs_view[p1, p2, q_idx + 1, :, i2[q_idx]] = right_slice.view( + from_block_size, n_rand_blocks, to_block_size + ) + + # Second-last query block + # corresponding to `second_last_context_layer` + attention_probs[:, :, -2 * from_block_size : -from_block_size, :to_block_size] = second_last_attn_weights[ + :, :, :, :to_block_size + ] # 1st key block (global) + attention_probs[ + :, :, -2 * from_block_size : -from_block_size, -3 * to_block_size : + ] = second_last_attn_weights[ + :, :, :, to_block_size : 4 * to_block_size + ] # last three blocks (global + sliding) + # random keys + for p1, i1, w1 in zip(range(bsz), rand_attn, second_last_attn_weights): + # p1, i1, w1 corresponds to batch_dim i.e. following operation is done for each sequence in batch + for p2, i2, w2 in zip(range(n_heads), i1, w1): + # p2, i2, w2 corresponds to head_dim i.e. following operation is done for each heads + attn_probs_view = attention_probs.view( + bsz, + n_heads, + from_seq_len // from_block_size, + from_block_size, + to_seq_len // to_block_size, + to_block_size, + ) + right_slice = w2[:, 4 * to_block_size :] + attn_probs_view[p1, p2, -2, :, i2[-1]] = right_slice.view( + from_block_size, n_rand_blocks, to_block_size + ) + + # last query block + # corresponding to `last_context_layer` + attention_probs[:, :, -from_block_size:, :] = last_attn_weights # all keys global + + else: + attention_probs = None + + return context_layer, attention_probs + + @staticmethod + def torch_gather_b2(params, indices): + # this operation is equivalent to tf.gather when batch_dims=2 + + if params.shape[:2] != indices.shape[:2]: + raise ValueError( + "Make sure that the first two dimensions of params and indices are identical, but" + f" they are params: {params.shape[:2]} vs. indices: {indices.shape[:2]}" + ) + num_indices_to_gather = indices.shape[-2] * indices.shape[-1] + num_indices_to_pick_from = params.shape[2] + + shift = torch.arange(indices.shape[0] * indices.shape[1] * num_indices_to_gather, device=indices.device) + indices_shift = torch.div(shift, num_indices_to_gather, rounding_mode="floor") * num_indices_to_pick_from + + flattened_indices = indices.view(-1) + indices_shift + flattened_params = params.reshape(-1, params.shape[-2], params.shape[-1]) + + out_flattened = flattened_params.index_select(0, flattened_indices) + + out = out_flattened.reshape(params.shape[:2] + (num_indices_to_gather,) + params.shape[3:]) + return out + + @staticmethod + def _create_rand_mask_from_inputs( + from_blocked_mask, + to_blocked_mask, + rand_attn, + num_attention_heads, + num_rand_blocks, + batch_size, + from_seq_length, + from_block_size, + ): + """ + Create 3D attention mask from a 2D tensor mask. + + Args: + from_blocked_mask: 2D Tensor of shape [batch_size, + from_seq_length//from_block_size, from_block_size]. + to_blocked_mask: int32 Tensor of shape [batch_size, + to_seq_length//to_block_size, to_block_size]. + rand_attn: [batch_size, num_attention_heads, + from_seq_length//from_block_size-2, num_rand_blocks] + num_attention_heads: int. Number of attention heads. + num_rand_blocks: int. Number of random chunks per row. + batch_size: int. Batch size for computation. + from_seq_length: int. length of from sequence. + from_block_size: int. size of block in from sequence. + + Returns: + float Tensor of shape [batch_size, num_attention_heads, from_seq_length//from_block_size-2, + from_block_size, num_rand_blocks*to_block_size]. + """ + num_windows = from_seq_length // from_block_size - 2 + rand_mask = torch.stack([p1[i1.flatten()] for p1, i1 in zip(to_blocked_mask, rand_attn)]) + rand_mask = rand_mask.view(batch_size, num_attention_heads, num_windows, num_rand_blocks * from_block_size) + rand_mask = torch.einsum("blq,bhlk->bhlqk", from_blocked_mask[:, 1:-1], rand_mask) + return rand_mask + + @staticmethod + def _get_rand_attn_plan(from_seq_length, from_block_size, num_rand_blocks): + """ + Gives the plan of where to put random attention. + + Args: + from_seq_length: int. length of from sequence. + from_block_size: int. size of block in from sequence. + num_rand_blocks: int. Number of random chunks per row. + + Returns: + plan_from_length: ending location of from block plan_num_rand_blocks: number of random ending location for + each block + """ + + plan_from_length = [] + plan_num_rand_blocks = [] + if (2 * num_rand_blocks + 5) < (from_seq_length // from_block_size): + plan_from_length.append(int((2 * num_rand_blocks + 5) * from_block_size)) + plan_num_rand_blocks.append(num_rand_blocks) + plan_from_length.append(from_seq_length) + plan_num_rand_blocks.append(0) + elif (num_rand_blocks + 5) < (from_seq_length // from_block_size): + plan_from_length.append(int((num_rand_blocks + 5) * from_block_size)) + plan_num_rand_blocks.append(num_rand_blocks // 2) + plan_from_length.append(from_seq_length) + plan_num_rand_blocks.append(num_rand_blocks - (num_rand_blocks // 2)) + else: + plan_from_length.append(from_seq_length) + plan_num_rand_blocks.append(num_rand_blocks) + + return plan_from_length, plan_num_rand_blocks + + def _bigbird_block_rand_mask( + self, from_seq_length, to_seq_length, from_block_size, to_block_size, num_rand_blocks, last_idx=-1 + ): + """ + Create adjacency list of random attention. + + Args: + from_seq_length: int. length of from sequence. + to_seq_length: int. length of to sequence. + from_block_size: int. size of block in from sequence. + to_block_size: int. size of block in to sequence. + num_rand_blocks: int. Number of random chunks per row. + last_idx: if -1 then num_rand_blocks blocks chosen anywhere in to sequence, + if positive then num_rand_blocks blocks chosen only up to last_idx. + + Returns: + adjacency list of size from_seq_length//from_block_size-2 by num_rand_blocks + """ + # using this method when from_seq_length in [1024, 3072, 4096] + + if from_seq_length // from_block_size != to_seq_length // to_block_size: + raise ValueError("Error the number of blocks needs to be same!") + + rand_attn = np.zeros((from_seq_length // from_block_size - 2, num_rand_blocks), dtype=np.int32) + # During inference (eval) no randomness + if not self.training: + return rand_attn + middle_seq = np.arange(1, to_seq_length // to_block_size - 1, dtype=np.int32) + last = to_seq_length // to_block_size - 1 + if last_idx > (2 * to_block_size): + last = (last_idx // to_block_size) - 1 + + r = num_rand_blocks # shorthand + for i in range(1, from_seq_length // from_block_size - 1): + start = i - 2 + end = i + if i == 1: + rand_attn[i - 1, :] = np.random.permutation(middle_seq[2:last])[:r] + elif i == 2: + rand_attn[i - 1, :] = np.random.permutation(middle_seq[3:last])[:r] + elif i == from_seq_length // from_block_size - 3: + rand_attn[i - 1, :] = np.random.permutation(middle_seq[:last])[:r] + # Missing -3: should have been sliced till last-3 + elif i == from_seq_length // from_block_size - 2: + rand_attn[i - 1, :] = np.random.permutation(middle_seq[:last])[:r] + # Missing -4: should have been sliced till last-4 + else: + if start > last: + start = last + rand_attn[i - 1, :] = np.random.permutation(middle_seq[:start])[:r] + elif (end + 1) == last: + rand_attn[i - 1, :] = np.random.permutation(middle_seq[:start])[:r] + else: + rand_attn[i - 1, :] = np.random.permutation( + np.concatenate((middle_seq[:start], middle_seq[end + 1 : last])) + )[:r] + return rand_attn + + def _bigbird_block_rand_mask_with_head( + self, + from_seq_length, + to_seq_length, + from_block_size, + to_block_size, + num_heads, + plan_from_length, + plan_num_rand_blocks, + window_block_left=1, + window_block_right=1, + global_block_top=1, + global_block_bottom=1, + global_block_left=1, + global_block_right=1, + ): + """ + Create adjacency list of random attention. + + Args: + from_seq_length: int. length of from sequence. + to_seq_length: int. length of to sequence. + from_block_size: int. size of block in from sequence. + to_block_size: int. size of block in to sequence. + num_heads: int. total number of heads. + plan_from_length: list. plan from length where num_random_blocks are chosen from. + plan_num_rand_blocks: list. number of rand blocks within the plan. + window_block_left: int. number of blocks of window to left of a block. + window_block_right: int. number of blocks of window to right of a block. + global_block_top: int. number of blocks at the top. + global_block_bottom: int. number of blocks at the bottom. + global_block_left: int. Number of blocks globally used to the left. + global_block_right: int. Number of blocks globally used to the right. + + Returns: + adjacency list of size num_head where each element is of size from_seq_length//from_block_size-2 by + num_rand_blocks + """ + # using this method when from_seq_length not in [1024, 3072, 4096] + + if from_seq_length // from_block_size != to_seq_length // to_block_size: + raise ValueError("Error the number of blocks needs to be same!") + + if from_seq_length not in plan_from_length: + raise ValueError("Error from sequence length not in plan!") + + # Total number of blocks in the mmask + num_blocks = from_seq_length // from_block_size + # Number of blocks per plan + plan_block_length = np.array(plan_from_length) // from_block_size + # till when to follow plan + max_plan_idx = plan_from_length.index(from_seq_length) + + # Random Attention adjacency list + rand_attn = [ + np.zeros((num_blocks, np.sum(plan_num_rand_blocks[: max_plan_idx + 1])), dtype=np.int32) + for i in range(num_heads) + ] + # During inference (eval) no randomness + if not self.training: + for nh in range(num_heads): + rand_attn[nh] = rand_attn[nh][global_block_top : num_blocks - global_block_bottom, :] + return rand_attn + + # We will go iteratively over the plan blocks and pick random number of + # Attention blocks from the legally allowed blocks + for plan_idx in range(max_plan_idx + 1): + rnd_r_cnt = 0 + if plan_idx > 0: + # set the row for all from_blocks starting from 0 to + # plan_block_length[plan_idx-1] + # column indx start fromm plan_block_length[plan_idx-1] and ends at + # plan_block_length[plan_idx] + if plan_num_rand_blocks[plan_idx] > 0: + rnd_r_cnt = int(np.sum(plan_num_rand_blocks[:plan_idx])) + curr_r_cnt = int(np.sum(plan_num_rand_blocks[: plan_idx + 1])) + for blk_rw_idx in range(global_block_top, plan_block_length[plan_idx - 1]): + for h in range(num_heads): + rand_attn[h][blk_rw_idx, rnd_r_cnt:curr_r_cnt] = self._get_single_block_row_attention( + block_id=blk_rw_idx, + to_start_block_id=plan_block_length[plan_idx - 1], + to_end_block_id=plan_block_length[plan_idx], + num_rand_blocks=plan_num_rand_blocks[plan_idx], + window_block_left=window_block_left, + window_block_right=window_block_right, + global_block_left=global_block_left, + global_block_right=global_block_right, + ) + + for pl_id in range(plan_idx): + if plan_num_rand_blocks[pl_id] == 0: + continue + for blk_rw_idx in range(plan_block_length[plan_idx - 1], plan_block_length[plan_idx]): + rnd_r_cnt = 0 + to_start_block_id = 0 + if pl_id > 0: + rnd_r_cnt = int(np.sum(plan_num_rand_blocks[:pl_id])) + to_start_block_id = plan_block_length[pl_id - 1] + curr_r_cnt = int(np.sum(plan_num_rand_blocks[: pl_id + 1])) + for h in range(num_heads): + rand_attn[h][blk_rw_idx, rnd_r_cnt:curr_r_cnt] = self._get_single_block_row_attention( + block_id=blk_rw_idx, + to_start_block_id=to_start_block_id, + to_end_block_id=plan_block_length[pl_id], + num_rand_blocks=plan_num_rand_blocks[pl_id], + window_block_left=window_block_left, + window_block_right=window_block_right, + global_block_left=global_block_left, + global_block_right=global_block_right, + ) + + if plan_num_rand_blocks[plan_idx] == 0: + continue + curr_r_cnt = int(np.sum(plan_num_rand_blocks[: plan_idx + 1])) + from_start_block_id = global_block_top + to_start_block_id = 0 + if plan_idx > 0: + rnd_r_cnt = int(np.sum(plan_num_rand_blocks[:plan_idx])) + from_start_block_id = plan_block_length[plan_idx - 1] + to_start_block_id = plan_block_length[plan_idx - 1] + + for blk_rw_idx in range(from_start_block_id, plan_block_length[plan_idx]): + for h in range(num_heads): + rand_attn[h][blk_rw_idx, rnd_r_cnt:curr_r_cnt] = self._get_single_block_row_attention( + block_id=blk_rw_idx, + to_start_block_id=to_start_block_id, + to_end_block_id=plan_block_length[plan_idx], + num_rand_blocks=plan_num_rand_blocks[plan_idx], + window_block_left=window_block_left, + window_block_right=window_block_right, + global_block_left=global_block_left, + global_block_right=global_block_right, + ) + + for nh in range(num_heads): + rand_attn[nh] = rand_attn[nh][global_block_top : num_blocks - global_block_bottom, :] + + return rand_attn + + @staticmethod + def _get_single_block_row_attention( + block_id, + to_start_block_id, + to_end_block_id, + num_rand_blocks, + window_block_left=1, + window_block_right=1, + global_block_left=1, + global_block_right=1, + ): + """ + For a single row block get random row attention. + + Args: + block_id: int. block id of row. + to_start_block_id: int. random attention column start id. + to_end_block_id: int. random attention column end id. + num_rand_blocks: int. number of random blocks to be selected. + window_block_left: int. number of blocks of window to left of a block. + window_block_right: int. number of blocks of window to right of a block. + global_block_left: int. Number of blocks globally used to the left. + global_block_right: int. Number of blocks globally used to the right. + + Returns: + row containing the random attention vector of size num_rand_blocks. + """ + # list of to_blocks from which to choose random attention + to_block_list = np.arange(to_start_block_id, to_end_block_id, dtype=np.int32) + # permute the blocks + perm_block = np.random.permutation(to_block_list) + + # illegal blocks for the current block id, using window + illegal_blocks = list(range(block_id - window_block_left, block_id + window_block_right + 1)) + + # Add blocks at the start and at the end + illegal_blocks.extend(list(range(global_block_left))) + illegal_blocks.extend(list(range(to_end_block_id - global_block_right, to_end_block_id))) + + # The second from_block cannot choose random attention on second last to_block + if block_id == 1: + illegal_blocks.append(to_end_block_id - 2) + + # The second last from_block cannot choose random attention on second to_block + if block_id == to_end_block_id - 2: + illegal_blocks.append(1) + + selected_random_blokcs = [] + + for i in range(to_end_block_id - to_start_block_id): + if perm_block[i] not in illegal_blocks: + selected_random_blokcs.append(perm_block[i]) + if len(selected_random_blokcs) == num_rand_blocks: + break + return np.array(selected_random_blokcs, dtype=np.int32) + + +# Copied from transformers.models.bert.modeling_bert.BertSelfOutput with Bert->BigBird +class BigBirdSelfOutput(nn.Module): + def __init__(self, config): + super().__init__() + self.dense = nn.Linear(config.hidden_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 BigBirdAttention(nn.Module): + def __init__(self, config, seed=None): + super().__init__() + self.attention_type = config.attention_type + self.config = config + self.seed = seed + + if self.config.attention_type == "original_full": + self.self = BigBirdSelfAttention(config) + elif self.config.attention_type == "block_sparse": + self.self = BigBirdBlockSparseAttention(config, seed) + else: + raise ValueError( + f"attention_type can either be original_full or block_sparse, but is {self.config.attention_type}" + ) + + self.output = BigBirdSelfOutput(config) + + def set_attention_type(self, value: str): + if value not in ["original_full", "block_sparse"]: + raise ValueError( + f"attention_type can only be set to either 'original_full' or 'block_sparse', but is {value}" + ) + # attention type is already correctly set + if value == self.attention_type: + return + + self.attention_type = value + if value == "original_full": + # copy all weights to new full attention class + attn_weights = BigBirdSelfAttention(self.config) + else: + # copy all weights to new sparse attention class + attn_weights = BigBirdBlockSparseAttention(self.config, self.seed) + + attn_weights.query = self.self.query + attn_weights.value = self.self.value + attn_weights.key = self.self.key + self.self = attn_weights + self.attention_type = value + if not self.training: + self.self.eval() + + def forward( + self, + hidden_states, + attention_mask=None, + head_mask=None, + encoder_hidden_states=None, + encoder_attention_mask=None, + past_key_value=None, + output_attentions=False, + # block_sparse config + band_mask=None, + from_mask=None, + to_mask=None, + from_blocked_mask=None, + to_blocked_mask=None, + ): + # fp16 compatibility + if band_mask is not None: + band_mask = band_mask.to(hidden_states.dtype) + if from_mask is not None: + from_mask = from_mask.to(hidden_states.dtype) + if to_mask is not None: + to_mask = to_mask.to(hidden_states.dtype) + if self.attention_type == "original_full": + self_outputs = self.self( + hidden_states, + attention_mask, + head_mask, + encoder_hidden_states, + encoder_attention_mask, + past_key_value, + output_attentions, + ) + else: + if encoder_hidden_states is not None: + raise ValueError("BigBird cannot be used as a decoder when config.attention_type != 'original_full'") + self_outputs = self.self( + hidden_states, band_mask, from_mask, to_mask, from_blocked_mask, to_blocked_mask, output_attentions + ) + + attention_output = self.output(self_outputs[0], hidden_states) + outputs = (attention_output,) + self_outputs[1:] # add attentions if we output them + return outputs + + +# Copied from transformers.models.bert.modeling_bert.BertIntermediate with Bert->BigBird +class BigBirdIntermediate(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 + + +# Copied from transformers.models.bert.modeling_bert.BertOutput with Bert->BigBird +class BigBirdOutput(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 BigBirdLayer(nn.Module): + def __init__(self, config, seed=None): + super().__init__() + self.config = config + self.attention_type = config.attention_type + self.chunk_size_feed_forward = config.chunk_size_feed_forward + self.seq_len_dim = 1 + self.attention = BigBirdAttention(config, seed=seed) + self.is_decoder = config.is_decoder + self.add_cross_attention = config.add_cross_attention + if self.add_cross_attention: + if not self.is_decoder: + raise TypeError(f"{self} should be used as a decoder model if cross attention is added") + self.crossattention = BigBirdAttention(config) + self.intermediate = BigBirdIntermediate(config) + self.output = BigBirdOutput(config) + + def set_attention_type(self, value: str): + if value not in ["original_full", "block_sparse"]: + raise ValueError( + f"attention_type can only be set to either 'original_full' or 'block_sparse', but is {value}" + ) + # attention type is already correctly set + if value == self.attention_type: + return + self.attention_type = value + self.attention.set_attention_type(value) + + if self.add_cross_attention: + self.crossattention.set_attention_type(value) + + def forward( + self, + hidden_states, + attention_mask=None, + head_mask=None, + encoder_hidden_states=None, + encoder_attention_mask=None, + band_mask=None, + from_mask=None, + to_mask=None, + blocked_encoder_mask=None, + past_key_value=None, + output_attentions=False, + ): + # decoder uni-directional self-attention cached key/values tuple is at positions 1,2 + self_attn_past_key_value = past_key_value[:2] if past_key_value is not None else None + self_attention_outputs = self.attention( + hidden_states, + attention_mask, + head_mask, + encoder_hidden_states=encoder_hidden_states, + encoder_attention_mask=encoder_attention_mask, + past_key_value=self_attn_past_key_value, + output_attentions=output_attentions, + band_mask=band_mask, + from_mask=from_mask, + to_mask=to_mask, + from_blocked_mask=blocked_encoder_mask, + to_blocked_mask=blocked_encoder_mask, + ) + attention_output = self_attention_outputs[0] + + # if decoder, the last output is tuple of self-attn cache + if self.is_decoder: + outputs = self_attention_outputs[1:-1] + present_key_value = self_attention_outputs[-1] + else: + outputs = self_attention_outputs[1:] # add self attentions if we output attention weights + + cross_attn_present_key_value = None + if self.is_decoder and encoder_hidden_states is not None: + 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`" + ) + + # cross_attn cached key/values tuple is at positions 3,4 of past_key_value tuple + cross_attn_past_key_value = past_key_value[-2:] if past_key_value is not None else None + cross_attention_outputs = self.crossattention( + attention_output, + attention_mask, + head_mask, + encoder_hidden_states, + encoder_attention_mask, + cross_attn_past_key_value, + output_attentions, + ) + attention_output = cross_attention_outputs[0] + outputs = outputs + cross_attention_outputs[1:-1] # add cross attentions if we output attention weights + + # add cross-attn cache to positions 3,4 of present_key_value tuple + cross_attn_present_key_value = cross_attention_outputs[-1] + present_key_value = present_key_value + cross_attn_present_key_value + + layer_output = apply_chunking_to_forward( + self.feed_forward_chunk, self.chunk_size_feed_forward, self.seq_len_dim, attention_output + ) + + outputs = (layer_output,) + outputs + + # if decoder, return the attn key/values as the last output + if self.is_decoder: + outputs = outputs + (present_key_value,) + + return outputs + + def feed_forward_chunk(self, attention_output): + intermediate_output = self.intermediate(attention_output) + layer_output = self.output(intermediate_output, attention_output) + return layer_output + + +class BigBirdEncoder(nn.Module): + def __init__(self, config): + super().__init__() + self.config = config + self.attention_type = config.attention_type + + self.layer = nn.ModuleList( + [BigBirdLayer(config, seed=layer_idx) for layer_idx in range(config.num_hidden_layers)] + ) + self.gradient_checkpointing = False + + def set_attention_type(self, value: str): + if value not in ["original_full", "block_sparse"]: + raise ValueError( + f"attention_type can only be set to either 'original_full' or 'block_sparse', but is {value}" + ) + # attention type is already correctly set + if value == self.attention_type: + return + self.attention_type = value + for layer in self.layer: + layer.set_attention_type(value) + + def forward( + self, + hidden_states, + attention_mask=None, + head_mask=None, + encoder_hidden_states=None, + encoder_attention_mask=None, + past_key_values=None, + use_cache=None, + output_attentions=False, + output_hidden_states=False, + band_mask=None, + from_mask=None, + to_mask=None, + blocked_encoder_mask=None, + return_dict=True, + ) -> Union[BaseModelOutputWithPastAndCrossAttentions, Tuple]: + all_hidden_states = () if output_hidden_states else None + all_self_attentions = () if output_attentions else None + all_cross_attentions = () if output_attentions and self.config.add_cross_attention else None + + if self.gradient_checkpointing and self.training: + if use_cache: + logger.warning_once( + "`use_cache=True` is incompatible with gradient checkpointing. Setting `use_cache=False`..." + ) + use_cache = False + + next_decoder_cache = () if use_cache else None + + for i, layer_module in enumerate(self.layer): + if output_hidden_states: + all_hidden_states = all_hidden_states + (hidden_states,) + + layer_head_mask = head_mask[i] if head_mask is not None else None + past_key_value = past_key_values[i] if past_key_values is not None else None + + if self.gradient_checkpointing and self.training: + layer_outputs = self._gradient_checkpointing_func( + layer_module.__call__, + hidden_states, + attention_mask, + layer_head_mask, + encoder_hidden_states, + encoder_attention_mask, + band_mask, + from_mask, + to_mask, + blocked_encoder_mask, + past_key_value, + output_attentions, + ) + else: + layer_outputs = layer_module( + hidden_states, + attention_mask, + layer_head_mask, + encoder_hidden_states, + encoder_attention_mask, + band_mask, + from_mask, + to_mask, + blocked_encoder_mask, + past_key_value, + output_attentions, + ) + + hidden_states = layer_outputs[0] + if use_cache: + next_decoder_cache += (layer_outputs[-1],) + if output_attentions: + all_self_attentions = all_self_attentions + (layer_outputs[1],) + if self.config.add_cross_attention: + all_cross_attentions = all_cross_attentions + (layer_outputs[2],) + + if output_hidden_states: + all_hidden_states = all_hidden_states + (hidden_states,) + + if not return_dict: + return tuple( + v + for v in [ + hidden_states, + next_decoder_cache, + all_hidden_states, + all_self_attentions, + all_cross_attentions, + ] + if v is not None + ) + return BaseModelOutputWithPastAndCrossAttentions( + last_hidden_state=hidden_states, + past_key_values=next_decoder_cache, + hidden_states=all_hidden_states, + attentions=all_self_attentions, + cross_attentions=all_cross_attentions, + ) + + +# Copied from transformers.models.bert.modeling_bert.BertPredictionHeadTransform with Bert->BigBird +class BigBirdPredictionHeadTransform(nn.Module): + def __init__(self, config): + super().__init__() + self.dense = nn.Linear(config.hidden_size, config.hidden_size) + if isinstance(config.hidden_act, str): + self.transform_act_fn = ACT2FN[config.hidden_act] + else: + self.transform_act_fn = config.hidden_act + self.LayerNorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps) + + def forward(self, hidden_states: torch.Tensor) -> torch.Tensor: + hidden_states = self.dense(hidden_states) + hidden_states = self.transform_act_fn(hidden_states) + hidden_states = self.LayerNorm(hidden_states) + return hidden_states + + +# Copied from transformers.models.bert.modeling_bert.BertLMPredictionHead with Bert->BigBird +class BigBirdLMPredictionHead(nn.Module): + def __init__(self, config): + super().__init__() + self.transform = BigBirdPredictionHeadTransform(config) + + # The output weights are the same as the input embeddings, but there is + # an output-only bias for each token. + self.decoder = nn.Linear(config.hidden_size, config.vocab_size, bias=False) + + self.bias = nn.Parameter(torch.zeros(config.vocab_size)) + + # Need a link between the two variables so that the bias is correctly resized with `resize_token_embeddings` + self.decoder.bias = self.bias + + def forward(self, hidden_states): + hidden_states = self.transform(hidden_states) + hidden_states = self.decoder(hidden_states) + return hidden_states + + +# Copied from transformers.models.bert.modeling_bert.BertOnlyMLMHead with Bert->BigBird +class BigBirdOnlyMLMHead(nn.Module): + def __init__(self, config): + super().__init__() + self.predictions = BigBirdLMPredictionHead(config) + + def forward(self, sequence_output: torch.Tensor) -> torch.Tensor: + prediction_scores = self.predictions(sequence_output) + return prediction_scores + + +# Copied from transformers.models.bert.modeling_bert.BertOnlyNSPHead with Bert->BigBird +class BigBirdOnlyNSPHead(nn.Module): + def __init__(self, config): + super().__init__() + self.seq_relationship = nn.Linear(config.hidden_size, 2) + + def forward(self, pooled_output): + seq_relationship_score = self.seq_relationship(pooled_output) + return seq_relationship_score + + +# Copied from transformers.models.bert.modeling_bert.BertPreTrainingHeads with Bert->BigBird +class BigBirdPreTrainingHeads(nn.Module): + def __init__(self, config): + super().__init__() + self.predictions = BigBirdLMPredictionHead(config) + self.seq_relationship = nn.Linear(config.hidden_size, 2) + + def forward(self, sequence_output, pooled_output): + prediction_scores = self.predictions(sequence_output) + seq_relationship_score = self.seq_relationship(pooled_output) + return prediction_scores, seq_relationship_score + + +class BigBirdPreTrainedModel(PreTrainedModel): + """ + An abstract class to handle weights initialization and a simple interface for downloading and loading pretrained + models. + """ + + config_class = BigBirdConfig + load_tf_weights = load_tf_weights_in_big_bird + base_model_prefix = "bert" + supports_gradient_checkpointing = True + + def _init_weights(self, module): + """Initialize the weights""" + if 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) + + +BIG_BIRD_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 ([`BigBirdConfig`]): 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. +""" + +BIG_BIRD_INPUTS_DOCSTRING = r""" + Args: + input_ids (`torch.LongTensor` of shape `({0})`): + Indices of input sequence tokens in the vocabulary. + + Indices can be obtained using [`AutoTokenizer`]. See [`PreTrainedTokenizer.encode`] and + [`PreTrainedTokenizer.__call__`] for details. + + [What are input IDs?](../glossary#input-ids) + attention_mask (`torch.FloatTensor` of shape `({0})`, *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**. + + [What are attention masks?](../glossary#attention-mask) + token_type_ids (`torch.LongTensor` of shape `({0})`, *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.LongTensor` of shape `({0})`, *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.FloatTensor` 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.FloatTensor` of shape `({0}, 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. + 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. +""" + + +@dataclass +class BigBirdForPreTrainingOutput(ModelOutput): + """ + Output type of [`BigBirdForPreTraining`]. + + Args: + loss (*optional*, returned when `labels` is provided, `torch.FloatTensor` of shape `(1,)`): + Total loss as the sum of the masked language modeling loss and the next sequence prediction + (classification) loss. + prediction_logits (`torch.FloatTensor` of shape `(batch_size, sequence_length, config.vocab_size)`): + Prediction scores of the language modeling head (scores for each vocabulary token before SoftMax). + seq_relationship_logits (`torch.FloatTensor` of shape `(batch_size, 2)`): + Prediction scores of the next sequence prediction (classification) head (scores of True/False continuation + before SoftMax). + hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`): + Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of + shape `(batch_size, sequence_length, hidden_size)`. + + Hidden-states of the model at the output of each layer plus the initial embedding outputs. + attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`): + Tuple of `torch.FloatTensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length, + sequence_length)`. + + Attentions weights after the attention softmax, used to compute the weighted average in the self-attention + heads. + """ + + loss: Optional[torch.FloatTensor] = None + prediction_logits: torch.FloatTensor = None + seq_relationship_logits: torch.FloatTensor = None + hidden_states: Optional[Tuple[torch.FloatTensor]] = None + attentions: Optional[Tuple[torch.FloatTensor]] = None + + +@dataclass +class BigBirdForQuestionAnsweringModelOutput(ModelOutput): + """ + Base class for outputs of question answering models. + + Args: + loss (`torch.FloatTensor` of shape `(1,)`, *optional*, returned when `labels` is provided): + Total span extraction loss is the sum of a Cross-Entropy for the start and end positions. + start_logits (`torch.FloatTensor` of shape `(batch_size, sequence_length)`): + Span-start scores (before SoftMax). + end_logits (`torch.FloatTensor` of shape `(batch_size, sequence_length)`): + Span-end scores (before SoftMax). + pooler_output (`torch.FloatTensor` of shape `(batch_size, 1)`): + pooler output from BigBigModel + hidden_states (`tuple(torch.FloatTensor)`, *optional*, returned when `output_hidden_states=True` is passed or when `config.output_hidden_states=True`): + Tuple of `torch.FloatTensor` (one for the output of the embeddings + one for the output of each layer) of + shape `(batch_size, sequence_length, hidden_size)`. + + Hidden-states of the model at the output of each layer plus the initial embedding outputs. + attentions (`tuple(torch.FloatTensor)`, *optional*, returned when `output_attentions=True` is passed or when `config.output_attentions=True`): + Tuple of `torch.FloatTensor` (one for each layer) of shape `(batch_size, num_heads, sequence_length, + sequence_length)`. + + Attentions weights after the attention softmax, used to compute the weighted average in the self-attention + heads. + """ + + loss: Optional[torch.FloatTensor] = None + start_logits: torch.FloatTensor = None + end_logits: torch.FloatTensor = None + pooler_output: torch.FloatTensor = None + hidden_states: Optional[Tuple[torch.FloatTensor]] = None + attentions: Optional[Tuple[torch.FloatTensor]] = None + + +@add_start_docstrings( + "The bare BigBird Model transformer outputting raw hidden-states without any specific head on top.", + BIG_BIRD_START_DOCSTRING, +) +class BigBirdModel(BigBirdPreTrainedModel): + """ + + The model can behave as an encoder (with only self-attention) as well as a decoder, in which case a layer of + cross-attention is added between the self-attention layers, following the architecture described in [Attention is + all you need](https://arxiv.org/abs/1706.03762) by Ashish Vaswani, Noam Shazeer, Niki Parmar, Jakob Uszkoreit, + Llion Jones, Aidan N. Gomez, Lukasz Kaiser and Illia Polosukhin. + + To behave as an decoder the model needs to be initialized with the `is_decoder` argument of the configuration set + to `True`. To be used in a Seq2Seq model, the model needs to initialized with both `is_decoder` argument and + `add_cross_attention` set to `True`; an `encoder_hidden_states` is then expected as an input to the forward pass. + """ + + def __init__(self, config, add_pooling_layer=True): + super().__init__(config) + self.attention_type = self.config.attention_type + self.config = config + + self.block_size = self.config.block_size + + self.embeddings = BigBirdEmbeddings(config) + self.encoder = BigBirdEncoder(config) + + if add_pooling_layer: + self.pooler = nn.Linear(config.hidden_size, config.hidden_size) + self.activation = nn.Tanh() + else: + self.pooler = None + self.activation = None + + if self.attention_type != "original_full" and config.add_cross_attention: + logger.warning( + "When using `BigBirdForCausalLM` as decoder, then `attention_type` must be `original_full`. Setting" + " `attention_type=original_full`" + ) + self.set_attention_type("original_full") + + # Initialize weights and apply final processing + self.post_init() + + def get_input_embeddings(self): + return self.embeddings.word_embeddings + + def set_input_embeddings(self, value): + self.embeddings.word_embeddings = value + + def set_attention_type(self, value: str): + if value not in ["original_full", "block_sparse"]: + raise ValueError( + f"attention_type can only be set to either 'original_full' or 'block_sparse', but is {value}" + ) + # attention type is already correctly set + if value == self.attention_type: + return + self.attention_type = value + self.encoder.set_attention_type(value) + + @add_start_docstrings_to_model_forward(BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, sequence_length")) + @add_code_sample_docstrings( + checkpoint=_CHECKPOINT_FOR_DOC, + output_type=BaseModelOutputWithPoolingAndCrossAttentions, + config_class=_CONFIG_FOR_DOC, + ) + def forward( + self, + input_ids: torch.LongTensor = None, + attention_mask: Optional[torch.FloatTensor] = None, + token_type_ids: Optional[torch.LongTensor] = None, + position_ids: Optional[torch.LongTensor] = None, + head_mask: Optional[torch.FloatTensor] = None, + inputs_embeds: Optional[torch.FloatTensor] = None, + encoder_hidden_states: Optional[torch.FloatTensor] = None, + encoder_attention_mask: Optional[torch.FloatTensor] = None, + past_key_values: Optional[Tuple[Tuple[torch.FloatTensor]]] = None, + use_cache: Optional[bool] = None, + output_attentions: Optional[bool] = None, + output_hidden_states: Optional[bool] = None, + return_dict: Optional[bool] = None, + ) -> Union[BaseModelOutputWithPoolingAndCrossAttentions, Tuple[torch.FloatTensor]]: + r""" + encoder_hidden_states (`torch.FloatTensor` of shape `(batch_size, sequence_length, hidden_size)`, *optional*): + Sequence of hidden-states at the output of the last layer of the encoder. Used in the cross-attention if + the model is configured as a decoder. + encoder_attention_mask (`torch.FloatTensor` of shape `(batch_size, sequence_length)`, *optional*): + Mask to avoid performing attention on the padding token indices of the encoder input. This mask is used in + the cross-attention if the model is configured as a decoder. Mask values selected in `[0, 1]`: + + - 1 for tokens that are **not masked**, + - 0 for tokens that are **masked**. + past_key_values (`tuple(tuple(torch.FloatTensor))` of length `config.n_layers` with each tuple having 4 tensors of shape `(batch_size, num_heads, sequence_length - 1, embed_size_per_head)`): + Contains precomputed key and value hidden states of the attention blocks. Can be used to speed up decoding. + If `past_key_values` are used, the user can optionally input only the last `decoder_input_ids` (those that + don't have their past key value states given to this model) of shape `(batch_size, 1)` instead of all + `decoder_input_ids` of shape `(batch_size, sequence_length)`. + 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 = 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 + + if self.config.is_decoder: + use_cache = use_cache if use_cache is not None else self.config.use_cache + else: + use_cache = False + + 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() + elif inputs_embeds is not None: + input_shape = inputs_embeds.size()[:-1] + else: + raise ValueError("You have to specify either input_ids or inputs_embeds") + + batch_size, seq_length = input_shape + device = input_ids.device if input_ids is not None else inputs_embeds.device + + # past_key_values_length + past_key_values_length = past_key_values[0][0].shape[2] if past_key_values is not None else 0 + + if attention_mask is None: + attention_mask = torch.ones(((batch_size, seq_length + past_key_values_length)), device=device) + if token_type_ids is None: + if hasattr(self.embeddings, "token_type_ids"): + buffered_token_type_ids = self.embeddings.token_type_ids[:, :seq_length] + buffered_token_type_ids_expanded = buffered_token_type_ids.expand(batch_size, seq_length) + token_type_ids = buffered_token_type_ids_expanded + else: + token_type_ids = torch.zeros(input_shape, dtype=torch.long, device=device) + + # in order to use block_sparse attention, sequence_length has to be at least + # bigger than all global attentions: 2 * block_size + # + sliding tokens: 3 * block_size + # + random tokens: 2 * num_random_blocks * block_size + max_tokens_to_attend = (5 + 2 * self.config.num_random_blocks) * self.config.block_size + if self.attention_type == "block_sparse" and seq_length <= max_tokens_to_attend: + # change attention_type from block_sparse to original_full + sequence_length = input_ids.size(1) if input_ids is not None else inputs_embeds.size(1) + logger.warning( + "Attention type 'block_sparse' is not possible if sequence_length: " + f"{sequence_length} <= num global tokens: 2 * config.block_size " + "+ min. num sliding tokens: 3 * config.block_size " + "+ config.num_random_blocks * config.block_size " + "+ additional buffer: config.num_random_blocks * config.block_size " + f"= {max_tokens_to_attend} with config.block_size " + f"= {self.config.block_size}, config.num_random_blocks " + f"= {self.config.num_random_blocks}. " + "Changing attention type to 'original_full'..." + ) + self.set_attention_type("original_full") + + if self.attention_type == "block_sparse": + ( + padding_len, + input_ids, + attention_mask, + token_type_ids, + position_ids, + inputs_embeds, + ) = self._pad_to_block_size( + input_ids=input_ids, + attention_mask=attention_mask, + token_type_ids=token_type_ids, + position_ids=position_ids, + inputs_embeds=inputs_embeds, + pad_token_id=self.config.pad_token_id, + ) + else: + padding_len = 0 + + if self.attention_type == "block_sparse": + blocked_encoder_mask, band_mask, from_mask, to_mask = self.create_masks_for_block_sparse_attn( + attention_mask, self.block_size + ) + extended_attention_mask = None + + elif self.attention_type == "original_full": + blocked_encoder_mask = None + band_mask = None + from_mask = None + to_mask = None + # We can provide a self-attention mask of dimensions [batch_size, from_seq_length, to_seq_length] + # ourselves in which case we just need to make it broadcastable to all heads. + extended_attention_mask: torch.Tensor = self.get_extended_attention_mask(attention_mask, input_shape) + else: + raise ValueError( + f"attention_type can either be original_full or block_sparse, but is {self.attention_type}" + ) + + # If a 2D or 3D attention mask is provided for the cross-attention + # we need to make broadcastable to [batch_size, num_heads, seq_length, seq_length] + if self.config.is_decoder and encoder_hidden_states is not None: + encoder_batch_size, encoder_sequence_length, _ = encoder_hidden_states.size() + encoder_hidden_shape = (encoder_batch_size, encoder_sequence_length) + if encoder_attention_mask is None: + encoder_attention_mask = torch.ones(encoder_hidden_shape, device=device) + encoder_extended_attention_mask = self.invert_attention_mask(encoder_attention_mask) + else: + encoder_extended_attention_mask = None + + # Prepare head mask if needed + # 1.0 in head_mask indicate we keep the head + # attention_probs has shape bsz x n_heads x N x N + # input head_mask has shape [num_heads] or [num_hidden_layers x num_heads] + # and head_mask is converted to shape [num_hidden_layers x batch x num_heads x seq_length x seq_length] + head_mask = self.get_head_mask(head_mask, self.config.num_hidden_layers) + + embedding_output = self.embeddings( + input_ids=input_ids, + position_ids=position_ids, + token_type_ids=token_type_ids, + inputs_embeds=inputs_embeds, + past_key_values_length=past_key_values_length, + ) + + encoder_outputs = self.encoder( + embedding_output, + attention_mask=extended_attention_mask, + head_mask=head_mask, + encoder_hidden_states=encoder_hidden_states, + encoder_attention_mask=encoder_extended_attention_mask, + past_key_values=past_key_values, + use_cache=use_cache, + output_attentions=output_attentions, + output_hidden_states=output_hidden_states, + band_mask=band_mask, + from_mask=from_mask, + to_mask=to_mask, + blocked_encoder_mask=blocked_encoder_mask, + return_dict=return_dict, + ) + sequence_output = encoder_outputs[0] + + pooler_output = self.activation(self.pooler(sequence_output[:, 0, :])) if (self.pooler is not None) else None + + # undo padding + if padding_len > 0: + # unpad `sequence_output` because the calling function is expecting a length == input_ids.size(1) + sequence_output = sequence_output[:, :-padding_len] + + if not return_dict: + return (sequence_output, pooler_output) + encoder_outputs[1:] + + return BaseModelOutputWithPoolingAndCrossAttentions( + last_hidden_state=sequence_output, + pooler_output=pooler_output, + past_key_values=encoder_outputs.past_key_values, + hidden_states=encoder_outputs.hidden_states, + attentions=encoder_outputs.attentions, + cross_attentions=encoder_outputs.cross_attentions, + ) + + @staticmethod + def create_masks_for_block_sparse_attn(attention_mask: torch.Tensor, block_size: int): + batch_size, seq_length = attention_mask.size() + if seq_length % block_size != 0: + raise ValueError( + f"Sequence length must be multiple of block size, but sequence length is {seq_length}, while block" + f" size is {block_size}." + ) + + def create_band_mask_from_inputs(from_blocked_mask, to_blocked_mask): + """ + Create 3D attention mask from a 2D tensor mask. + + Args: + from_blocked_mask: 2D Tensor of shape [batch_size, + from_seq_length//from_block_size, from_block_size]. + to_blocked_mask: int32 Tensor of shape [batch_size, + to_seq_length//to_block_size, to_block_size]. + + Returns: + float Tensor of shape [batch_size, 1, from_seq_length//from_block_size-4, from_block_size, + 3*to_block_size]. + """ + exp_blocked_to_pad = torch.cat( + [to_blocked_mask[:, 1:-3], to_blocked_mask[:, 2:-2], to_blocked_mask[:, 3:-1]], dim=2 + ) + band_mask = torch.einsum("blq,blk->blqk", from_blocked_mask[:, 2:-2], exp_blocked_to_pad) + band_mask.unsqueeze_(1) + return band_mask + + blocked_encoder_mask = attention_mask.view(batch_size, seq_length // block_size, block_size) + band_mask = create_band_mask_from_inputs(blocked_encoder_mask, blocked_encoder_mask) + + from_mask = attention_mask.view(batch_size, 1, seq_length, 1) + to_mask = attention_mask.view(batch_size, 1, 1, seq_length) + + return blocked_encoder_mask, band_mask, from_mask, to_mask + + def _pad_to_block_size( + self, + input_ids: torch.Tensor, + attention_mask: torch.Tensor, + token_type_ids: torch.Tensor, + position_ids: torch.Tensor, + inputs_embeds: torch.Tensor, + pad_token_id: int, + ): + """A helper function to pad tokens and mask to work with implementation of BigBird block-sparse attention.""" + # padding + block_size = self.config.block_size + + input_shape = input_ids.shape if input_ids is not None else inputs_embeds.shape + batch_size, seq_len = input_shape[:2] + + padding_len = (block_size - seq_len % block_size) % block_size + if padding_len > 0: + logger.warning_once( + f"Input ids are automatically padded from {seq_len} to {seq_len + padding_len} to be a multiple of " + f"`config.block_size`: {block_size}" + ) + if input_ids is not None: + input_ids = nn.functional.pad(input_ids, (0, padding_len), value=pad_token_id) + if position_ids is not None: + # pad with position_id = pad_token_id as in modeling_bigbird.BigBirdEmbeddings + position_ids = nn.functional.pad(position_ids, (0, padding_len), value=pad_token_id) + if inputs_embeds is not None: + input_ids_padding = inputs_embeds.new_full( + (batch_size, padding_len), + self.config.pad_token_id, + dtype=torch.long, + ) + inputs_embeds_padding = self.embeddings(input_ids_padding) + inputs_embeds = torch.cat([inputs_embeds, inputs_embeds_padding], dim=-2) + + attention_mask = nn.functional.pad( + attention_mask, (0, padding_len), value=False + ) # no attention on the padding tokens + token_type_ids = nn.functional.pad(token_type_ids, (0, padding_len), value=0) # pad with token_type_id = 0 + + return padding_len, input_ids, attention_mask, token_type_ids, position_ids, inputs_embeds + + +class BigBirdForPreTraining(BigBirdPreTrainedModel): + _tied_weights_keys = ["cls.predictions.decoder.weight", "cls.predictions.decoder.bias"] + + def __init__(self, config): + super().__init__(config) + + self.bert = BigBirdModel(config, add_pooling_layer=True) + self.cls = BigBirdPreTrainingHeads(config) + + # Initialize weights and apply final processing + self.post_init() + + def get_output_embeddings(self): + return self.cls.predictions.decoder + + def set_output_embeddings(self, new_embeddings): + self.cls.predictions.decoder = new_embeddings + + @add_start_docstrings_to_model_forward(BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, sequence_length")) + @replace_return_docstrings(output_type=BigBirdForPreTrainingOutput, config_class=_CONFIG_FOR_DOC) + def forward( + self, + input_ids: torch.LongTensor = None, + attention_mask: Optional[torch.FloatTensor] = None, + token_type_ids: Optional[torch.LongTensor] = None, + position_ids: Optional[torch.LongTensor] = None, + head_mask: Optional[torch.FloatTensor] = None, + inputs_embeds: Optional[torch.FloatTensor] = None, + labels: Optional[torch.FloatTensor] = None, + next_sentence_label: Optional[torch.LongTensor] = None, + output_attentions: Optional[bool] = None, + output_hidden_states: Optional[bool] = None, + return_dict: Optional[bool] = None, + ) -> Union[BigBirdForPreTrainingOutput, Tuple[torch.FloatTensor]]: + r""" + labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*): + Labels for computing the masked language modeling loss. Indices should be in `[-100, 0, ..., + config.vocab_size]` (see `input_ids` docstring) Tokens with indices set to `-100` are ignored (masked), the + loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]` + next_sentence_label (`torch.LongTensor` of shape `(batch_size,)`, *optional*): + Labels for computing the next sequence prediction (classification) loss. If specified, nsp loss will be + added to masked_lm loss. Input should be a sequence pair (see `input_ids` docstring) Indices should be in + `[0, 1]`: + + - 0 indicates sequence B is a continuation of sequence A, + - 1 indicates sequence B is a random sequence. + kwargs (`Dict[str, any]`, optional, defaults to *{}*): + Used to hide legacy arguments that have been deprecated. + + Returns: + + Example: + + ```python + >>> from transformers import AutoTokenizer, BigBirdForPreTraining + >>> import torch + + >>> tokenizer = AutoTokenizer.from_pretrained("google/bigbird-roberta-base") + >>> model = BigBirdForPreTraining.from_pretrained("google/bigbird-roberta-base") + + >>> inputs = tokenizer("Hello, my dog is cute", return_tensors="pt") + >>> outputs = model(**inputs) + + >>> prediction_logits = outputs.prediction_logits + >>> seq_relationship_logits = outputs.seq_relationship_logits + ```""" + return_dict = return_dict if return_dict is not None else self.config.use_return_dict + + outputs = self.bert( + input_ids, + attention_mask=attention_mask, + token_type_ids=token_type_ids, + position_ids=position_ids, + head_mask=head_mask, + inputs_embeds=inputs_embeds, + output_attentions=output_attentions, + output_hidden_states=output_hidden_states, + return_dict=return_dict, + ) + + sequence_output, pooled_output = outputs[:2] + prediction_scores, seq_relationship_score = self.cls(sequence_output, pooled_output) + + total_loss = None + if labels is not None: + loss_fct = CrossEntropyLoss() + total_loss = loss_fct(prediction_scores.view(-1, self.config.vocab_size), labels.view(-1)) + + if next_sentence_label is not None and total_loss is not None: + next_sentence_loss = loss_fct(seq_relationship_score.view(-1, 2), next_sentence_label.view(-1)) + total_loss = total_loss + next_sentence_loss + + if not return_dict: + output = (prediction_scores, seq_relationship_score) + outputs[2:] + return ((total_loss,) + output) if total_loss is not None else output + + return BigBirdForPreTrainingOutput( + loss=total_loss, + prediction_logits=prediction_scores, + seq_relationship_logits=seq_relationship_score, + hidden_states=outputs.hidden_states, + attentions=outputs.attentions, + ) + + +@add_start_docstrings("""BigBird Model with a `language modeling` head on top.""", BIG_BIRD_START_DOCSTRING) +class BigBirdForMaskedLM(BigBirdPreTrainedModel): + _tied_weights_keys = ["cls.predictions.decoder.weight", "cls.predictions.decoder.bias"] + + def __init__(self, config): + super().__init__(config) + + if config.is_decoder: + logger.warning( + "If you want to use `BigBirdForMaskedLM` make sure `config.is_decoder=False` for " + "bi-directional self-attention." + ) + + self.bert = BigBirdModel(config) + self.cls = BigBirdOnlyMLMHead(config) + + # Initialize weights and apply final processing + self.post_init() + + def get_output_embeddings(self): + return self.cls.predictions.decoder + + def set_output_embeddings(self, new_embeddings): + self.cls.predictions.decoder = new_embeddings + + @add_start_docstrings_to_model_forward(BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, sequence_length")) + @replace_return_docstrings(output_type=MaskedLMOutput, config_class=_CONFIG_FOR_DOC) + def forward( + self, + input_ids: torch.LongTensor = None, + attention_mask: Optional[torch.FloatTensor] = None, + token_type_ids: Optional[torch.LongTensor] = None, + position_ids: Optional[torch.LongTensor] = None, + head_mask: Optional[torch.FloatTensor] = None, + inputs_embeds: Optional[torch.FloatTensor] = None, + encoder_hidden_states: Optional[torch.FloatTensor] = None, + encoder_attention_mask: Optional[torch.FloatTensor] = None, + labels: Optional[torch.LongTensor] = None, + output_attentions: Optional[bool] = None, + output_hidden_states: Optional[bool] = None, + return_dict: Optional[bool] = None, + ) -> Union[MaskedLMOutput, Tuple[torch.FloatTensor]]: + r""" + labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*): + Labels for computing the masked language modeling loss. Indices should be in `[-100, 0, ..., + config.vocab_size]` (see `input_ids` docstring) Tokens with indices set to `-100` are ignored (masked), the + loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]`. + + Returns: + + Example: + + ```python + >>> import torch + >>> from transformers import AutoTokenizer, BigBirdForMaskedLM + >>> from datasets import load_dataset + + >>> tokenizer = AutoTokenizer.from_pretrained("google/bigbird-roberta-base") + >>> model = BigBirdForMaskedLM.from_pretrained("google/bigbird-roberta-base") + >>> squad_ds = load_dataset("squad_v2", split="train") # doctest: +IGNORE_RESULT + + >>> # select random long article + >>> LONG_ARTICLE_TARGET = squad_ds[81514]["context"] + >>> # select random sentence + >>> LONG_ARTICLE_TARGET[332:398] + 'the highest values are very close to the theoretical maximum value' + + >>> # add mask_token + >>> LONG_ARTICLE_TO_MASK = LONG_ARTICLE_TARGET.replace("maximum", "[MASK]") + >>> inputs = tokenizer(LONG_ARTICLE_TO_MASK, return_tensors="pt") + >>> # long article input + >>> list(inputs["input_ids"].shape) + [1, 919] + + >>> with torch.no_grad(): + ... logits = model(**inputs).logits + >>> # retrieve index of [MASK] + >>> mask_token_index = (inputs.input_ids == tokenizer.mask_token_id)[0].nonzero(as_tuple=True)[0] + >>> predicted_token_id = logits[0, mask_token_index].argmax(axis=-1) + >>> tokenizer.decode(predicted_token_id) + 'maximum' + ``` + + ```python + >>> labels = tokenizer(LONG_ARTICLE_TARGET, return_tensors="pt")["input_ids"] + >>> labels = torch.where(inputs.input_ids == tokenizer.mask_token_id, labels, -100) + >>> outputs = model(**inputs, labels=labels) + >>> round(outputs.loss.item(), 2) + 1.99 + ``` + """ + return_dict = return_dict if return_dict is not None else self.config.use_return_dict + + outputs = self.bert( + input_ids, + attention_mask=attention_mask, + token_type_ids=token_type_ids, + position_ids=position_ids, + head_mask=head_mask, + inputs_embeds=inputs_embeds, + encoder_hidden_states=encoder_hidden_states, + encoder_attention_mask=encoder_attention_mask, + output_attentions=output_attentions, + output_hidden_states=output_hidden_states, + return_dict=return_dict, + ) + + sequence_output = outputs[0] + prediction_scores = self.cls(sequence_output) + + masked_lm_loss = None + if labels is not None: + loss_fct = CrossEntropyLoss() # -100 index = padding token + masked_lm_loss = loss_fct(prediction_scores.view(-1, self.config.vocab_size), labels.view(-1)) + + if not return_dict: + output = (prediction_scores,) + outputs[2:] + return ((masked_lm_loss,) + output) if masked_lm_loss is not None else output + + return MaskedLMOutput( + loss=masked_lm_loss, + logits=prediction_scores, + hidden_states=outputs.hidden_states, + attentions=outputs.attentions, + ) + + def prepare_inputs_for_generation(self, input_ids, attention_mask=None, **model_kwargs): + input_shape = input_ids.shape + effective_batch_size = input_shape[0] + + # add a dummy token + if self.config.pad_token_id is None: + raise ValueError("The PAD token should be defined for generation") + attention_mask = torch.cat([attention_mask, attention_mask.new_zeros((attention_mask.shape[0], 1))], dim=-1) + dummy_token = torch.full( + (effective_batch_size, 1), self.config.pad_token_id, dtype=torch.long, device=input_ids.device + ) + input_ids = torch.cat([input_ids, dummy_token], dim=1) + + return {"input_ids": input_ids, "attention_mask": attention_mask} + + +@add_start_docstrings( + """BigBird Model with a `language modeling` head on top for CLM fine-tuning.""", BIG_BIRD_START_DOCSTRING +) +class BigBirdForCausalLM(BigBirdPreTrainedModel): + _tied_weights_keys = ["cls.predictions.decoder.weight", "cls.predictions.decoder.bias"] + + def __init__(self, config): + super().__init__(config) + + if not config.is_decoder: + logger.warning("If you want to use `BigBirdForCausalLM` as a standalone, add `is_decoder=True.`") + + self.bert = BigBirdModel(config) + self.cls = BigBirdOnlyMLMHead(config) + + # Initialize weights and apply final processing + self.post_init() + + def get_output_embeddings(self): + return self.cls.predictions.decoder + + def set_output_embeddings(self, new_embeddings): + self.cls.predictions.decoder = new_embeddings + + @add_start_docstrings_to_model_forward(BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, sequence_length")) + @add_code_sample_docstrings( + checkpoint=_CHECKPOINT_FOR_DOC, + output_type=CausalLMOutputWithCrossAttentions, + config_class=_CONFIG_FOR_DOC, + ) + def forward( + self, + input_ids: torch.LongTensor = None, + attention_mask: Optional[torch.FloatTensor] = None, + token_type_ids: Optional[torch.LongTensor] = None, + position_ids: Optional[torch.LongTensor] = None, + head_mask: Optional[torch.FloatTensor] = None, + inputs_embeds: Optional[torch.FloatTensor] = None, + encoder_hidden_states: Optional[torch.FloatTensor] = None, + encoder_attention_mask: Optional[torch.FloatTensor] = None, + past_key_values: Optional[Tuple[Tuple[torch.FloatTensor]]] = None, + labels: Optional[torch.LongTensor] = None, + use_cache: Optional[bool] = None, + output_attentions: Optional[bool] = None, + output_hidden_states: Optional[bool] = None, + return_dict: Optional[bool] = None, + ) -> Union[CausalLMOutputWithCrossAttentions, Tuple[torch.FloatTensor]]: + r""" + encoder_hidden_states (`torch.FloatTensor` of shape `(batch_size, sequence_length, hidden_size)`, *optional*): + Sequence of hidden-states at the output of the last layer of the encoder. Used in the cross-attention if + the model is configured as a decoder. + encoder_attention_mask (`torch.FloatTensor` of shape `(batch_size, sequence_length)`, *optional*): + Mask to avoid performing attention on the padding token indices of the encoder input. This mask is used in + the cross-attention if the model is configured as a decoder. Mask values selected in `[0, 1]`: + + - 1 for tokens that are **not masked**, + - 0 for tokens that are **masked**. + past_key_values (`tuple(tuple(torch.FloatTensor))` of length `config.n_layers` with each tuple having 4 tensors of shape `(batch_size, num_heads, sequence_length - 1, embed_size_per_head)`): + Contains precomputed key and value hidden states of the attention blocks. Can be used to speed up decoding. + If `past_key_values` are used, the user can optionally input only the last `decoder_input_ids` (those that + don't have their past key value states given to this model) of shape `(batch_size, 1)` instead of all + `decoder_input_ids` of shape `(batch_size, sequence_length)`. + labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*): + Labels for computing the left-to-right language modeling loss (next word prediction). Indices should be in + `[-100, 0, ..., config.vocab_size]` (see `input_ids` docstring) Tokens with indices set to `-100` are + ignored (masked), the loss is only computed for the tokens with labels n `[0, ..., config.vocab_size]`. + 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`). + """ + return_dict = return_dict if return_dict is not None else self.config.use_return_dict + + outputs = self.bert( + input_ids, + attention_mask=attention_mask, + token_type_ids=token_type_ids, + position_ids=position_ids, + head_mask=head_mask, + inputs_embeds=inputs_embeds, + encoder_hidden_states=encoder_hidden_states, + encoder_attention_mask=encoder_attention_mask, + past_key_values=past_key_values, + use_cache=use_cache, + output_attentions=output_attentions, + output_hidden_states=output_hidden_states, + return_dict=return_dict, + ) + + sequence_output = outputs[0] + prediction_scores = self.cls(sequence_output) + + lm_loss = None + if labels is not None: + # we are doing next-token prediction; shift prediction scores and input ids by one + shifted_prediction_scores = prediction_scores[:, :-1, :].contiguous() + labels = labels[:, 1:].contiguous() + loss_fct = CrossEntropyLoss() + lm_loss = loss_fct(shifted_prediction_scores.view(-1, self.config.vocab_size), labels.view(-1)) + + if not return_dict: + output = (prediction_scores,) + outputs[2:] + return ((lm_loss,) + output) if lm_loss is not None else output + + return CausalLMOutputWithCrossAttentions( + loss=lm_loss, + logits=prediction_scores, + past_key_values=outputs.past_key_values, + hidden_states=outputs.hidden_states, + attentions=outputs.attentions, + cross_attentions=outputs.cross_attentions, + ) + + def prepare_inputs_for_generation(self, input_ids, past_key_values=None, attention_mask=None, **model_kwargs): + input_shape = input_ids.shape + + # if model is used as a decoder in encoder-decoder model, the decoder attention mask is created on the fly + if attention_mask is None: + attention_mask = input_ids.new_ones(input_shape) + + # cut decoder_input_ids if past_key_values is used + if past_key_values is not None: + past_length = past_key_values[0][0].shape[2] + + # Some generation methods already pass only the last input ID + if input_ids.shape[1] > past_length: + remove_prefix_length = past_length + else: + # Default to old behavior: keep only final ID + remove_prefix_length = input_ids.shape[1] - 1 + + input_ids = input_ids[:, remove_prefix_length:] + + return {"input_ids": input_ids, "attention_mask": attention_mask, "past_key_values": past_key_values} + + def _reorder_cache(self, past_key_values, beam_idx): + reordered_past = () + for layer_past in past_key_values: + reordered_past += ( + tuple(past_state.index_select(0, beam_idx.to(past_state.device)) for past_state in layer_past[:2]) + + layer_past[2:], + ) + return reordered_past + + +class BigBirdClassificationHead(nn.Module): + """Head for sentence-level classification tasks.""" + + def __init__(self, config): + super().__init__() + self.dense = nn.Linear(config.hidden_size, config.hidden_size) + classifier_dropout = ( + config.classifier_dropout if config.classifier_dropout is not None else config.hidden_dropout_prob + ) + self.dropout = nn.Dropout(classifier_dropout) + self.out_proj = nn.Linear(config.hidden_size, config.num_labels) + + self.config = config + + def forward(self, features, **kwargs): + x = features[:, 0, :] # take token (equiv. to [CLS]) + x = self.dropout(x) + x = self.dense(x) + x = ACT2FN[self.config.hidden_act](x) + x = self.dropout(x) + x = self.out_proj(x) + return x + + +@add_start_docstrings( + """ + BigBird Model transformer with a sequence classification/regression head on top (a linear layer on top of the + pooled output) e.g. for GLUE tasks. + """, + BIG_BIRD_START_DOCSTRING, +) +class BigBirdForSequenceClassification(BigBirdPreTrainedModel): + def __init__(self, config): + super().__init__(config) + self.num_labels = config.num_labels + self.config = config + self.bert = BigBirdModel(config) + self.classifier = BigBirdClassificationHead(config) + + # Initialize weights and apply final processing + self.post_init() + + @add_start_docstrings_to_model_forward(BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, sequence_length")) + @replace_return_docstrings(output_type=SequenceClassifierOutput, config_class=_CONFIG_FOR_DOC) + def forward( + self, + input_ids: torch.LongTensor = None, + attention_mask: Optional[torch.FloatTensor] = None, + token_type_ids: Optional[torch.LongTensor] = None, + position_ids: Optional[torch.LongTensor] = None, + head_mask: Optional[torch.FloatTensor] = None, + inputs_embeds: Optional[torch.FloatTensor] = None, + labels: Optional[torch.LongTensor] = None, + output_attentions: Optional[bool] = None, + output_hidden_states: Optional[bool] = None, + return_dict: Optional[bool] = None, + ) -> Union[SequenceClassifierOutput, Tuple[torch.FloatTensor]]: + r""" + labels (`torch.LongTensor` of shape `(batch_size,)`, *optional*): + Labels for computing the sequence classification/regression loss. Indices should be in `[0, ..., + config.num_labels - 1]`. If `config.num_labels == 1` a regression loss is computed (Mean-Square loss), If + `config.num_labels > 1` a classification loss is computed (Cross-Entropy). + + Returns: + + Example: + + ```python + >>> import torch + >>> from transformers import AutoTokenizer, BigBirdForSequenceClassification + >>> from datasets import load_dataset + + >>> tokenizer = AutoTokenizer.from_pretrained("l-yohai/bigbird-roberta-base-mnli") + >>> model = BigBirdForSequenceClassification.from_pretrained("l-yohai/bigbird-roberta-base-mnli") + >>> squad_ds = load_dataset("squad_v2", split="train") # doctest: +IGNORE_RESULT + + >>> LONG_ARTICLE = squad_ds[81514]["context"] + >>> inputs = tokenizer(LONG_ARTICLE, return_tensors="pt") + >>> # long input article + >>> list(inputs["input_ids"].shape) + [1, 919] + + >>> with torch.no_grad(): + ... logits = model(**inputs).logits + >>> predicted_class_id = logits.argmax().item() + >>> model.config.id2label[predicted_class_id] + 'LABEL_0' + ``` + + ```python + >>> num_labels = len(model.config.id2label) + >>> model = BigBirdForSequenceClassification.from_pretrained( + ... "l-yohai/bigbird-roberta-base-mnli", num_labels=num_labels + ... ) + >>> labels = torch.tensor(1) + >>> loss = model(**inputs, labels=labels).loss + >>> round(loss.item(), 2) + 1.13 + ``` + """ + return_dict = return_dict if return_dict is not None else self.config.use_return_dict + + outputs = self.bert( + input_ids, + attention_mask=attention_mask, + token_type_ids=token_type_ids, + position_ids=position_ids, + head_mask=head_mask, + inputs_embeds=inputs_embeds, + output_attentions=output_attentions, + output_hidden_states=output_hidden_states, + return_dict=return_dict, + ) + + sequence_output = outputs[0] + logits = self.classifier(sequence_output) + + loss = None + if labels is not None: + if self.config.problem_type is None: + if self.num_labels == 1: + self.config.problem_type = "regression" + elif self.num_labels > 1 and (labels.dtype == torch.long or labels.dtype == torch.int): + self.config.problem_type = "single_label_classification" + else: + self.config.problem_type = "multi_label_classification" + + if self.config.problem_type == "regression": + loss_fct = MSELoss() + if self.num_labels == 1: + loss = loss_fct(logits.squeeze(), labels.squeeze()) + else: + loss = loss_fct(logits, labels) + elif self.config.problem_type == "single_label_classification": + loss_fct = CrossEntropyLoss() + loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1)) + elif self.config.problem_type == "multi_label_classification": + loss_fct = BCEWithLogitsLoss() + loss = loss_fct(logits, labels) + + if not return_dict: + output = (logits,) + outputs[2:] + return ((loss,) + output) if loss is not None else output + + return SequenceClassifierOutput( + loss=loss, + logits=logits, + hidden_states=outputs.hidden_states, + attentions=outputs.attentions, + ) + + +@add_start_docstrings( + """ + BigBird Model with a multiple choice classification head on top (a linear layer on top of the pooled output and a + softmax) e.g. for RocStories/SWAG tasks. + """, + BIG_BIRD_START_DOCSTRING, +) +class BigBirdForMultipleChoice(BigBirdPreTrainedModel): + def __init__(self, config): + super().__init__(config) + + self.bert = BigBirdModel(config) + self.dropout = nn.Dropout(config.hidden_dropout_prob) + self.classifier = nn.Linear(config.hidden_size, 1) + + # Initialize weights and apply final processing + self.post_init() + + @add_start_docstrings_to_model_forward( + BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, num_choices, sequence_length") + ) + @add_code_sample_docstrings( + checkpoint=_CHECKPOINT_FOR_DOC, + output_type=MultipleChoiceModelOutput, + config_class=_CONFIG_FOR_DOC, + ) + def forward( + self, + input_ids: torch.LongTensor = None, + attention_mask: Optional[torch.FloatTensor] = None, + token_type_ids: Optional[torch.LongTensor] = None, + position_ids: Optional[torch.LongTensor] = None, + head_mask: Optional[torch.FloatTensor] = None, + inputs_embeds: Optional[torch.FloatTensor] = None, + labels: Optional[torch.LongTensor] = None, + output_attentions: Optional[bool] = None, + output_hidden_states: Optional[bool] = None, + return_dict: Optional[bool] = None, + ) -> Union[MultipleChoiceModelOutput, Tuple[torch.FloatTensor]]: + r""" + labels (`torch.LongTensor` of shape `(batch_size,)`, *optional*): + Labels for computing the multiple choice classification loss. Indices should be in `[0, ..., + num_choices-1]` where `num_choices` is the size of the second dimension of the input tensors. (See + `input_ids` above) + """ + return_dict = return_dict if return_dict is not None else self.config.use_return_dict + num_choices = input_ids.shape[1] if input_ids is not None else inputs_embeds.shape[1] + + input_ids = input_ids.view(-1, input_ids.size(-1)) if input_ids is not None else None + attention_mask = attention_mask.view(-1, attention_mask.size(-1)) if attention_mask is not None else None + token_type_ids = token_type_ids.view(-1, token_type_ids.size(-1)) if token_type_ids is not None else None + position_ids = position_ids.view(-1, position_ids.size(-1)) if position_ids is not None else None + inputs_embeds = ( + inputs_embeds.view(-1, inputs_embeds.size(-2), inputs_embeds.size(-1)) + if inputs_embeds is not None + else None + ) + + outputs = self.bert( + input_ids, + attention_mask=attention_mask, + token_type_ids=token_type_ids, + position_ids=position_ids, + head_mask=head_mask, + inputs_embeds=inputs_embeds, + output_attentions=output_attentions, + output_hidden_states=output_hidden_states, + return_dict=return_dict, + ) + + pooled_output = outputs[1] + + pooled_output = self.dropout(pooled_output) + logits = self.classifier(pooled_output) + reshaped_logits = logits.view(-1, num_choices) + + loss = None + if labels is not None: + loss_fct = CrossEntropyLoss() + loss = loss_fct(reshaped_logits, labels) + + if not return_dict: + output = (reshaped_logits,) + outputs[2:] + return ((loss,) + output) if loss is not None else output + + return MultipleChoiceModelOutput( + loss=loss, + logits=reshaped_logits, + hidden_states=outputs.hidden_states, + attentions=outputs.attentions, + ) + + +@add_start_docstrings( + """ + BigBird Model with a token classification head on top (a linear layer on top of the hidden-states output) e.g. for + Named-Entity-Recognition (NER) tasks. + """, + BIG_BIRD_START_DOCSTRING, +) +class BigBirdForTokenClassification(BigBirdPreTrainedModel): + def __init__(self, config): + super().__init__(config) + self.num_labels = config.num_labels + + self.bert = BigBirdModel(config) + classifier_dropout = ( + config.classifier_dropout if config.classifier_dropout is not None else config.hidden_dropout_prob + ) + self.dropout = nn.Dropout(classifier_dropout) + self.classifier = nn.Linear(config.hidden_size, config.num_labels) + + # Initialize weights and apply final processing + self.post_init() + + @add_start_docstrings_to_model_forward(BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, sequence_length")) + @add_code_sample_docstrings( + checkpoint=_CHECKPOINT_FOR_DOC, + output_type=TokenClassifierOutput, + config_class=_CONFIG_FOR_DOC, + ) + def forward( + self, + input_ids: torch.LongTensor = None, + attention_mask: Optional[torch.FloatTensor] = None, + token_type_ids: Optional[torch.LongTensor] = None, + position_ids: Optional[torch.LongTensor] = None, + head_mask: Optional[torch.FloatTensor] = None, + inputs_embeds: Optional[torch.FloatTensor] = None, + labels: Optional[torch.LongTensor] = None, + output_attentions: Optional[bool] = None, + output_hidden_states: Optional[bool] = None, + return_dict: Optional[bool] = None, + ) -> Union[TokenClassifierOutput, Tuple[torch.FloatTensor]]: + r""" + labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*): + Labels for computing the token classification loss. Indices should be in `[0, ..., config.num_labels - 1]`. + """ + return_dict = return_dict if return_dict is not None else self.config.use_return_dict + + outputs = self.bert( + input_ids, + attention_mask=attention_mask, + token_type_ids=token_type_ids, + position_ids=position_ids, + head_mask=head_mask, + inputs_embeds=inputs_embeds, + output_attentions=output_attentions, + output_hidden_states=output_hidden_states, + return_dict=return_dict, + ) + + sequence_output = outputs[0] + + sequence_output = self.dropout(sequence_output) + logits = self.classifier(sequence_output) + + loss = None + if labels is not None: + loss_fct = CrossEntropyLoss() + loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1)) + + if not return_dict: + output = (logits,) + outputs[2:] + return ((loss,) + output) if loss is not None else output + + return TokenClassifierOutput( + loss=loss, + logits=logits, + hidden_states=outputs.hidden_states, + attentions=outputs.attentions, + ) + + +class BigBirdForQuestionAnsweringHead(nn.Module): + """Head for question answering tasks.""" + + def __init__(self, config): + super().__init__() + self.dropout = nn.Dropout(config.hidden_dropout_prob) + self.intermediate = BigBirdIntermediate(config) + self.output = BigBirdOutput(config) + self.qa_outputs = nn.Linear(config.hidden_size, config.num_labels) + + def forward(self, encoder_output): + hidden_states = self.dropout(encoder_output) + hidden_states = self.intermediate(hidden_states) + hidden_states = self.output(hidden_states, encoder_output) + hidden_states = self.qa_outputs(hidden_states) + return hidden_states + + +@add_start_docstrings( + """ + BigBird Model with a span classification head on top for extractive question-answering tasks like SQuAD (a linear + layers on top of the hidden-states output to compute `span start logits` and `span end logits`). + """, + BIG_BIRD_START_DOCSTRING, +) +class BigBirdForQuestionAnswering(BigBirdPreTrainedModel): + def __init__(self, config, add_pooling_layer=False): + super().__init__(config) + + config.num_labels = 2 + self.num_labels = config.num_labels + self.sep_token_id = config.sep_token_id + + self.bert = BigBirdModel(config, add_pooling_layer=add_pooling_layer) + self.qa_classifier = BigBirdForQuestionAnsweringHead(config) + + # Initialize weights and apply final processing + self.post_init() + + @add_start_docstrings_to_model_forward(BIG_BIRD_INPUTS_DOCSTRING.format("batch_size, sequence_length")) + @replace_return_docstrings(output_type=BigBirdForQuestionAnsweringModelOutput, config_class=_CONFIG_FOR_DOC) + def forward( + self, + input_ids: Optional[torch.LongTensor] = None, + attention_mask: Optional[torch.FloatTensor] = None, + question_lengths: Optional[torch.Tensor] = None, + token_type_ids: Optional[torch.LongTensor] = None, + position_ids: Optional[torch.LongTensor] = None, + head_mask: Optional[torch.FloatTensor] = None, + inputs_embeds: Optional[torch.FloatTensor] = None, + start_positions: Optional[torch.LongTensor] = None, + end_positions: Optional[torch.LongTensor] = None, + output_attentions: Optional[bool] = None, + output_hidden_states: Optional[bool] = None, + return_dict: Optional[bool] = None, + ) -> Union[BigBirdForQuestionAnsweringModelOutput, Tuple[torch.FloatTensor]]: + r""" + start_positions (`torch.LongTensor` of shape `(batch_size,)`, *optional*): + Labels for position (index) of the start of the labelled span for computing the token classification loss. + Positions are clamped to the length of the sequence (`sequence_length`). Position outside of the sequence + are not taken into account for computing the loss. + end_positions (`torch.LongTensor` of shape `(batch_size,)`, *optional*): + Labels for position (index) of the end of the labelled span for computing the token classification loss. + Positions are clamped to the length of the sequence (`sequence_length`). Position outside of the sequence + are not taken into account for computing the loss. + + Returns: + + Example: + + ```python + >>> import torch + >>> from transformers import AutoTokenizer, BigBirdForQuestionAnswering + >>> from datasets import load_dataset + + >>> tokenizer = AutoTokenizer.from_pretrained("google/bigbird-roberta-base") + >>> model = BigBirdForQuestionAnswering.from_pretrained("google/bigbird-roberta-base") + >>> squad_ds = load_dataset("squad_v2", split="train") # doctest: +IGNORE_RESULT + + >>> # select random article and question + >>> LONG_ARTICLE = squad_ds[81514]["context"] + >>> QUESTION = squad_ds[81514]["question"] + >>> QUESTION + 'During daytime how high can the temperatures reach?' + + >>> inputs = tokenizer(QUESTION, LONG_ARTICLE, return_tensors="pt") + >>> # long article and question input + >>> list(inputs["input_ids"].shape) + [1, 929] + + >>> with torch.no_grad(): + ... outputs = model(**inputs) + + >>> answer_start_index = outputs.start_logits.argmax() + >>> answer_end_index = outputs.end_logits.argmax() + >>> predict_answer_token_ids = inputs.input_ids[0, answer_start_index : answer_end_index + 1] + >>> predict_answer_token = tokenizer.decode(predict_answer_token_ids) + ``` + + ```python + >>> target_start_index, target_end_index = torch.tensor([130]), torch.tensor([132]) + >>> outputs = model(**inputs, start_positions=target_start_index, end_positions=target_end_index) + >>> loss = outputs.loss + ``` + """ + return_dict = return_dict if return_dict is not None else self.config.use_return_dict + + seqlen = input_ids.size(1) if input_ids is not None else inputs_embeds.size(1) + + if question_lengths is None and input_ids is not None: + # assuming input_ids format: context + question_lengths = torch.argmax(input_ids.eq(self.sep_token_id).int(), dim=-1) + 1 + question_lengths.unsqueeze_(1) + + logits_mask = None + if question_lengths is not None: + # setting lengths logits to `-inf` + logits_mask = self.prepare_question_mask(question_lengths, seqlen) + if token_type_ids is None: + token_type_ids = torch.ones(logits_mask.size(), dtype=int, device=logits_mask.device) - logits_mask + logits_mask = logits_mask + logits_mask[:, 0] = False + logits_mask.unsqueeze_(2) + + outputs = self.bert( + input_ids, + attention_mask=attention_mask, + token_type_ids=token_type_ids, + position_ids=position_ids, + head_mask=head_mask, + inputs_embeds=inputs_embeds, + output_attentions=output_attentions, + output_hidden_states=output_hidden_states, + return_dict=return_dict, + ) + + sequence_output = outputs[0] + logits = self.qa_classifier(sequence_output) + + if logits_mask is not None: + # removing question tokens from the competition + logits = logits - logits_mask * 1e6 + + start_logits, end_logits = logits.split(1, dim=-1) + start_logits = start_logits.squeeze(-1).contiguous() + end_logits = end_logits.squeeze(-1).contiguous() + + total_loss = None + if start_positions is not None and end_positions is not None: + # If we are on multi-GPU, split add a dimension + if len(start_positions.size()) > 1: + start_positions = start_positions.squeeze(-1) + if len(end_positions.size()) > 1: + end_positions = end_positions.squeeze(-1) + # sometimes the start/end positions are outside our model inputs, we ignore these terms + ignored_index = start_logits.size(1) + start_positions = start_positions.clamp(0, ignored_index) + end_positions = end_positions.clamp(0, ignored_index) + + loss_fct = CrossEntropyLoss(ignore_index=ignored_index) + start_loss = loss_fct(start_logits, start_positions) + end_loss = loss_fct(end_logits, end_positions) + total_loss = (start_loss + end_loss) / 2 + + if not return_dict: + output = (start_logits, end_logits) + outputs[2:] + return ((total_loss,) + output) if total_loss is not None else output + + return BigBirdForQuestionAnsweringModelOutput( + loss=total_loss, + start_logits=start_logits, + end_logits=end_logits, + pooler_output=outputs.pooler_output, + hidden_states=outputs.hidden_states, + attentions=outputs.attentions, + ) + + @staticmethod + def prepare_question_mask(q_lengths: torch.Tensor, maxlen: int): + # q_lengths -> (bz, 1) + mask = torch.arange(0, maxlen).to(q_lengths.device) + mask.unsqueeze_(0) # -> (1, maxlen) + mask = torch.where(mask < q_lengths, 1, 0) + return mask