Source code for fairseq.modules.multihead_attention

# Copyright (c) Facebook, Inc. and its affiliates.
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.

import math
from typing import Dict, List, Optional, Tuple

import torch
import torch.nn.functional as F
from torch import Tensor, nn
from torch.nn import Parameter

    from xformers.components.attention import build_attention
    from xformers.components.attention.utils import maybe_merge_masks

    _xformers_available = True
except ImportError:
    _xformers_available = False

from fairseq import utils
from fairseq.incremental_decoding_utils import with_incremental_state
from fairseq.modules.fairseq_dropout import FairseqDropout
from fairseq.modules.quant_noise import quant_noise

# TODO: move this into xformers?
# TODO: uint8 input type should just output a bool
def _mask_for_xformers(mask: Tensor, to_dtype: Optional[torch.dtype] = None):
    call to pytorch multihead accepts three mask types:
        - ByteTensor where non-zero means to mask
        - FloatTensor which is an additive mask
        - BoolTensor where True means to mask
    xFormers currently accepts boolean and additive maks. For boolean masks
    the values have opposite meaning. For a BoolTensor True mean to keep the value.
    float_types = [torch.float, torch.float16]
    # If an input mask is a float it is an additive mask. Otherwise it is either uint8 or bool.
    additive = mask.dtype in float_types
    # If to_dype is not specified, keep same dtype as mask.
    to_dtype = mask.dtype if to_dtype is None else to_dtype
    to_additive = to_dtype in float_types

    if additive:
        if to_additive:
        mask = mask < 0

    if to_additive:
        # return additive mask
        new_mask = torch.zeros_like(mask, dtype=to_dtype)
        new_mask = new_mask.masked_fill_(mask, -float("inf"))
        return new_mask

    # In xFormers True is value to keep rather than value to mask
    mask =
    mask =
    return mask

[docs]@with_incremental_state class MultiheadAttention(nn.Module): """Multi-headed attention. See "Attention Is All You Need" for more details. """ def __init__( self, embed_dim, num_heads, kdim=None, vdim=None, dropout=0.0, bias=True, add_bias_kv=False, add_zero_attn=False, self_attention=False, encoder_decoder_attention=False, q_noise=0.0, qn_block_size=8, # TODO: pass in config rather than string. # config defined in xformers.components.attention.AttentionConfig xformers_att_config: Optional[str] = None, xformers_blocksparse_layout: Optional[ torch.Tensor ] = None, # This should be part of the config xformers_blocksparse_blocksize: Optional[ int ] = 16, # This should be part of the config ): super().__init__() xformers_att_config = utils.eval_str_dict(xformers_att_config) self.use_xformers = xformers_att_config is not None if self.use_xformers and not _xformers_available: raise ImportError("\n\n Please install xFormers.") self.embed_dim = embed_dim self.kdim = kdim if kdim is not None else embed_dim self.vdim = vdim if vdim is not None else embed_dim self.qkv_same_dim = self.kdim == embed_dim and self.vdim == embed_dim self.num_heads = num_heads self.dropout_module = FairseqDropout( dropout, module_name=self.__class__.__name__ ) self.head_dim = embed_dim // num_heads assert ( self.head_dim * num_heads == self.embed_dim ), "embed_dim must be divisible by num_heads" self.scaling = self.head_dim**-0.5 self.self_attention = self_attention self.encoder_decoder_attention = encoder_decoder_attention assert not self.self_attention or self.qkv_same_dim, ( "Self-attention requires query, key and " "value to be of the same size" ) self.k_proj = quant_noise( nn.Linear(self.kdim, embed_dim, bias=bias), q_noise, qn_block_size ) self.v_proj = quant_noise( nn.Linear(self.vdim, embed_dim, bias=bias), q_noise, qn_block_size ) self.q_proj = quant_noise( nn.Linear(embed_dim, embed_dim, bias=bias), q_noise, qn_block_size ) self.out_proj = quant_noise( nn.Linear(embed_dim, embed_dim, bias=bias), q_noise, qn_block_size ) if add_bias_kv: self.bias_k = Parameter(torch.Tensor(1, 1, embed_dim)) self.bias_v = Parameter(torch.Tensor(1, 1, embed_dim)) else: self.bias_k = self.bias_v = None self.add_zero_attn = add_zero_attn self.beam_size = 1 self.reset_parameters() if self.use_xformers: xformers_att_config["dropout"] = xformers_att_config.get("dropout", dropout) xformers_att_config["num_heads"] = xformers_att_config.get( "num_heads", num_heads ) if xformers_blocksparse_layout is not None: # Could be part of a single config passed only once xformers_att_config["block_size"] = xformers_blocksparse_blocksize xformers_att_config["layout"] = xformers_blocksparse_layout xformers_att_config["name"] = "blocksparse" self.attention = build_attention(xformers_att_config) self.onnx_trace = False self.skip_embed_dim_check = False
[docs] def prepare_for_onnx_export_(self): self.onnx_trace = True
[docs] def reset_parameters(self): if self.qkv_same_dim: # Empirically observed the convergence to be much better with # the scaled initialization nn.init.xavier_uniform_(self.k_proj.weight, gain=1 / math.sqrt(2)) nn.init.xavier_uniform_(self.v_proj.weight, gain=1 / math.sqrt(2)) nn.init.xavier_uniform_(self.q_proj.weight, gain=1 / math.sqrt(2)) else: nn.init.xavier_uniform_(self.k_proj.weight) nn.init.xavier_uniform_(self.v_proj.weight) nn.init.xavier_uniform_(self.q_proj.weight) nn.init.xavier_uniform_(self.out_proj.weight) if self.out_proj.bias is not None: nn.init.constant_(self.out_proj.bias, 0.0) if self.bias_k is not None: nn.init.xavier_normal_(self.bias_k) if self.bias_v is not None: nn.init.xavier_normal_(self.bias_v)
def _get_reserve_head_index(self, num_heads_to_keep: int): k_proj_heads_norm = [] q_proj_heads_norm = [] v_proj_heads_norm = [] for i in range(self.num_heads): start_idx = i * self.head_dim end_idx = (i + 1) * self.head_dim k_proj_heads_norm.append( torch.sum( torch.abs( self.k_proj.weight[ start_idx:end_idx, ] ) ).tolist() + torch.sum(torch.abs(self.k_proj.bias[start_idx:end_idx])).tolist() ) q_proj_heads_norm.append( torch.sum( torch.abs( self.q_proj.weight[ start_idx:end_idx, ] ) ).tolist() + torch.sum(torch.abs(self.q_proj.bias[start_idx:end_idx])).tolist() ) v_proj_heads_norm.append( torch.sum( torch.abs( self.v_proj.weight[ start_idx:end_idx, ] ) ).tolist() + torch.sum(torch.abs(self.v_proj.bias[start_idx:end_idx])).tolist() ) heads_norm = [] for i in range(self.num_heads): heads_norm.append( k_proj_heads_norm[i] + q_proj_heads_norm[i] + v_proj_heads_norm[i] ) sorted_head_index = sorted( range(self.num_heads), key=lambda k: heads_norm[k], reverse=True ) reserve_head_index = [] for i in range(num_heads_to_keep): start = sorted_head_index[i] * self.head_dim end = (sorted_head_index[i] + 1) * self.head_dim reserve_head_index.append((start, end)) return reserve_head_index def _adaptive_prune_heads(self, reserve_head_index: List[Tuple[int, int]]): new_q_weight = [] new_q_bias = [] new_k_weight = [] new_k_bias = [] new_v_weight = [] new_v_bias = [] new_out_proj_weight = [] for ele in reserve_head_index: start_idx, end_idx = ele new_q_weight.append( self.q_proj.weight[ start_idx:end_idx, ] ) new_q_bias.append(self.q_proj.bias[start_idx:end_idx]) new_k_weight.append( self.k_proj.weight[ start_idx:end_idx, ] ) new_k_bias.append(self.k_proj.bias[start_idx:end_idx]) new_v_weight.append( self.v_proj.weight[ start_idx:end_idx, ] ) new_v_bias.append(self.v_proj.bias[start_idx:end_idx]) new_out_proj_weight.append(self.out_proj.weight[:, start_idx:end_idx]) new_q_weight = new_k_weight = new_v_weight = new_out_proj_weight =, dim=-1).detach() new_q_weight.requires_grad = True new_k_weight.requires_grad = True new_v_weight.requires_grad = True new_out_proj_weight.requires_grad = True new_q_bias = new_q_bias.requires_grad = True new_k_bias = new_k_bias.requires_grad = True new_v_bias = new_v_bias.requires_grad = True self.q_proj.weight = torch.nn.Parameter(new_q_weight) self.q_proj.bias = torch.nn.Parameter(new_q_bias) self.k_proj.weight = torch.nn.Parameter(new_k_weight) self.k_proj.bias = torch.nn.Parameter(new_k_bias) self.v_proj.weight = torch.nn.Parameter(new_v_weight) self.v_proj.bias = torch.nn.Parameter(new_v_bias) self.out_proj.weight = torch.nn.Parameter(new_out_proj_weight) self.num_heads = len(reserve_head_index) self.embed_dim = self.head_dim * self.num_heads self.q_proj.out_features = self.embed_dim self.k_proj.out_features = self.embed_dim self.v_proj.out_features = self.embed_dim def _set_skip_embed_dim_check(self): self.skip_embed_dim_check = True def _pad_masks( self, key_padding_mask: Optional[Tensor], attn_mask: Optional[Tensor], ) -> Tuple[Optional[Tensor], Optional[Tensor]]: if attn_mask is not None: shape = attn_mask.size()[:-1] + torch.Size([1]) attn_mask =[attn_mask, attn_mask.new_zeros(shape)], dim=-1) if key_padding_mask is not None: shape = key_padding_mask.size()[:-1] + torch.Size([1]) key_padding_mask = [ key_padding_mask, key_padding_mask.new_zeros(shape), ], dim=-1, ) return key_padding_mask, attn_mask def _add_bias( self, k: Tensor, v: Tensor, key_padding_mask: Optional[Tensor], attn_mask: Optional[Tensor], bsz: int, ) -> Tuple[Tensor, Tensor, Optional[Tensor], Optional[Tensor]]: assert self.bias_k is not None assert self.bias_v is not None k =[k, self.bias_k.repeat(1, bsz, 1)]) v =[v, self.bias_v.repeat(1, bsz, 1)]) key_padding_mask, attn_mask = self._pad_masks( key_padding_mask=key_padding_mask, attn_mask=attn_mask ) return k, v, key_padding_mask, attn_mask def _append_zero_attn( self, k: Tensor, v: Tensor, key_padding_mask: Optional[Tensor], attn_mask: Optional[Tensor], ) -> Tuple[Tensor, Tensor, Optional[Tensor], Optional[Tensor]]: zero_attn_shape = k.size()[:-2] + torch.Size([1]) + k.size()[-1:] k = [k, torch.zeros(zero_attn_shape, dtype=k.dtype, device=k.device)], dim=-2 ) v = [v, torch.zeros(zero_attn_shape, dtype=v.dtype, device=v.device)], dim=-2 ) key_padding_mask, attn_mask = self._pad_masks( key_padding_mask=key_padding_mask, attn_mask=attn_mask ) return k, v, key_padding_mask, attn_mask def _xformers_attn_forward( self, query, key: Optional[Tensor], value: Optional[Tensor], key_padding_mask: Optional[Tensor] = None, need_weights: bool = True, attn_mask: Optional[Tensor] = None, ) -> Tuple[Tensor, Optional[Tensor]]: tgt_len, bsz, embed_dim = query.size() if key_padding_mask is not None: assert key_padding_mask.size(0) == bsz assert key_padding_mask.size(1) == tgt_len if self.self_attention: key = query value = query elif self.encoder_decoder_attention: value = key q = self.q_proj(query) k = self.k_proj(key) v = self.v_proj(value) if self.bias_k is not None: assert self.bias_v is not None k, v, attn_mask, key_padding_mask = self._add_bias( k, v, attn_mask, key_padding_mask, bsz ) def fold_heads(x): return ( x.contiguous() .view(-1, bsz * self.num_heads, self.head_dim) .transpose(0, 1) ) def split_heads(x): return ( x.contiguous() .view(-1, bsz, self.num_heads, self.head_dim) .transpose(0, 1) .transpose(1, 2) ) massage = split_heads if self.attention.requires_head_dimension else fold_heads q = massage(q) if k is not None: k = massage(k) if v is not None: v = massage(v) if self.add_zero_attn: k, v, key_padding_mask, attn_mask = self._append_zero_attn( k=k, v=v, key_padding_mask=key_padding_mask, attn_mask=attn_mask ) kwargs = {} if attn_mask is not None and self.attention.supports_attention_mask: attn_mask = _mask_for_xformers(attn_mask, to_dtype=q.dtype) kwargs["att_mask"] = attn_mask if key_padding_mask is not None: key_padding_mask = _mask_for_xformers(key_padding_mask, to_dtype=torch.bool) if not self.attention.requires_separate_masks: attn_mask = maybe_merge_masks( attn_mask, key_padding_mask, batch_size=bsz, src_len=k.size(-2), tgt_len=q.size(-2), num_heads=self.num_heads, ) key_padding_mask = None kwargs["att_mask"] = attn_mask if self.attention.supports_key_padding_mask: kwargs["key_padding_mask"] = key_padding_mask y = self.attention(q, k, v, **kwargs) y = ( y.view(bsz, self.num_heads, tgt_len, self.head_dim) .transpose(1, 2) .flatten(start_dim=2, end_dim=3) .transpose(0, 1) ) assert list(y.size()) == [tgt_len, bsz, embed_dim] # Dropout not needed because already applied in attention. # It is applied to the attention weights before matmul with v. y = self.out_proj(y) # TODO: support returning attention weights if needed. return y, None
[docs] def forward( self, query, key: Optional[Tensor], value: Optional[Tensor], key_padding_mask: Optional[Tensor] = None, incremental_state: Optional[Dict[str, Dict[str, Optional[Tensor]]]] = None, need_weights: bool = True, static_kv: bool = False, attn_mask: Optional[Tensor] = None, before_softmax: bool = False, need_head_weights: bool = False, ) -> Tuple[Tensor, Optional[Tensor]]: """Input shape: Time x Batch x Channel Args: key_padding_mask (ByteTensor, optional): mask to exclude keys that are pads, of shape `(batch, src_len)`, where padding elements are indicated by 1s. need_weights (bool, optional): return the attention weights, averaged over heads (default: False). attn_mask (ByteTensor, optional): typically used to implement causal attention, where the mask prevents the attention from looking forward in time (default: None). before_softmax (bool, optional): return the raw attention weights and values before the attention softmax. need_head_weights (bool, optional): return the attention weights for each head. Implies *need_weights*. Default: return the average attention weights over all heads. """ if need_head_weights: need_weights = True is_tpu = query.device.type == "xla" tgt_len, bsz, embed_dim = query.size() src_len = tgt_len if not self.skip_embed_dim_check: assert ( embed_dim == self.embed_dim ), f"query dim {embed_dim} != {self.embed_dim}" assert list(query.size()) == [tgt_len, bsz, embed_dim] if key is not None: src_len, key_bsz, _ = key.size() if not torch.jit.is_scripting(): assert value is not None assert src_len, key_bsz == value.shape[:2] if ( not self.onnx_trace and not is_tpu # don't use PyTorch version on TPUs and incremental_state is None and not static_kv # A workaround for quantization to work. Otherwise JIT compilation # treats bias in linear module as method. and not torch.jit.is_scripting() # The Multihead attention implemented in pytorch forces strong dimension check # for input embedding dimention and K,Q,V projection dimension. # Since pruning will break the dimension check and it is not easy to modify the pytorch API, # it is preferred to bypass the pytorch MHA when we need to skip embed_dim_check and not self.skip_embed_dim_check ): assert key is not None and value is not None if self.use_xformers: return self._xformers_attn_forward( query, key, value, key_padding_mask, need_weights, attn_mask ) else: return F.multi_head_attention_forward( query, key, value, self.embed_dim, self.num_heads, torch.empty([0]),, self.k_proj.bias, self.v_proj.bias)), self.bias_k, self.bias_v, self.add_zero_attn, self.dropout_module.p, self.out_proj.weight, self.out_proj.bias, or self.dropout_module.apply_during_inference, key_padding_mask, need_weights, attn_mask, use_separate_proj_weight=True, q_proj_weight=self.q_proj.weight, k_proj_weight=self.k_proj.weight, v_proj_weight=self.v_proj.weight, ) if incremental_state is not None: saved_state = self._get_input_buffer(incremental_state) if saved_state is not None and "prev_key" in saved_state: # previous time steps are cached - no need to recompute # key and value if they are static if static_kv: assert self.encoder_decoder_attention and not self.self_attention key = value = None else: saved_state = None if self.self_attention: q = self.q_proj(query) k = self.k_proj(query) v = self.v_proj(query) elif self.encoder_decoder_attention: # encoder-decoder attention q = self.q_proj(query) if key is None: assert value is None k = v = None else: if self.beam_size > 1 and bsz == key.size(1): # key is [T, bsz*beam_size, C], reduce to [T, bsz, C] key = key.view(key.size(0), -1, self.beam_size, key.size(2))[ :, :, 0, : ] if key_padding_mask is not None: key_padding_mask = key_padding_mask.view( -1, self.beam_size, key_padding_mask.size(1) )[:, 0, :] k = self.k_proj(key) v = self.v_proj(key) else: assert key is not None and value is not None q = self.q_proj(query) k = self.k_proj(key) v = self.v_proj(value) q *= self.scaling if self.bias_k is not None: assert self.bias_v is not None k, v, attn_mask, key_padding_mask = self._add_bias( k, v, attn_mask, key_padding_mask, bsz ) q = ( q.contiguous() .view(tgt_len, bsz * self.num_heads, self.head_dim) .transpose(0, 1) ) kv_bsz = bsz # need default value for scripting if k is not None: kv_bsz = k.size(1) k = ( k.contiguous() .view(-1, kv_bsz * self.num_heads, self.head_dim) .transpose(0, 1) ) if v is not None: v = ( v.contiguous() .view(-1, kv_bsz * self.num_heads, self.head_dim) .transpose(0, 1) ) if saved_state is not None: # saved states are stored with shape (bsz, num_heads, seq_len, head_dim) if "prev_key" in saved_state: _prev_key = saved_state["prev_key"] assert _prev_key is not None kv_bsz = _prev_key.size(0) prev_key = _prev_key.view(kv_bsz * self.num_heads, -1, self.head_dim) if static_kv: k = prev_key else: assert k is not None k =[prev_key, k], dim=1) src_len = k.size(1) if "prev_value" in saved_state: _prev_value = saved_state["prev_value"] assert _prev_value is not None assert kv_bsz == _prev_value.size(0) prev_value = _prev_value.view( kv_bsz * self.num_heads, -1, self.head_dim ) if static_kv: v = prev_value else: assert v is not None v =[prev_value, v], dim=1) prev_key_padding_mask: Optional[Tensor] = None if "prev_key_padding_mask" in saved_state: prev_key_padding_mask = saved_state["prev_key_padding_mask"] assert k is not None and v is not None key_padding_mask = MultiheadAttention._append_prev_key_padding_mask( key_padding_mask=key_padding_mask, prev_key_padding_mask=prev_key_padding_mask, batch_size=kv_bsz, src_len=k.size(1), static_kv=static_kv, ) saved_state["prev_key"] = k.view(kv_bsz, self.num_heads, -1, self.head_dim) saved_state["prev_value"] = v.view( kv_bsz, self.num_heads, -1, self.head_dim ) saved_state["prev_key_padding_mask"] = key_padding_mask # In this branch incremental_state is never None assert incremental_state is not None incremental_state = self._set_input_buffer(incremental_state, saved_state) assert k is not None assert k.size(1) == src_len # This is part of a workaround to get around fork/join parallelism # not supporting Optional types. if key_padding_mask is not None and key_padding_mask.dim() == 0: key_padding_mask = None if key_padding_mask is not None: assert key_padding_mask.size(0) == kv_bsz assert key_padding_mask.size(1) == src_len if self.add_zero_attn: assert v is not None src_len += 1 k, v, key_padding_mask, attn_mask = self._append_zero_attn( k=k, v=v, key_padding_mask=key_padding_mask, attn_mask=attn_mask ) if self.encoder_decoder_attention and bsz != kv_bsz: attn_weights = torch.einsum( "bxhtd,bhsd->bxhts", q.view((kv_bsz, -1, self.num_heads) + q.size()[1:]), k.view((kv_bsz, self.num_heads) + k.size()[1:]), ) attn_weights = attn_weights.reshape((-1,) + attn_weights.size()[-2:]) else: attn_weights = torch.bmm(q, k.transpose(1, 2)) attn_weights = self.apply_sparse_mask(attn_weights, tgt_len, src_len, bsz) assert list(attn_weights.size()) == [bsz * self.num_heads, tgt_len, src_len] if attn_mask is not None: attn_mask = attn_mask.unsqueeze(0) if self.onnx_trace: attn_mask = attn_mask.repeat(attn_weights.size(0), 1, 1) attn_weights += attn_mask if key_padding_mask is not None: # don't attend to padding symbols attn_weights = attn_weights.view(bsz, self.num_heads, tgt_len, src_len) if not is_tpu: attn_weights = attn_weights.view( kv_bsz, -1, self.num_heads, tgt_len, src_len ) attn_weights = attn_weights.masked_fill( key_padding_mask.unsqueeze(1) .unsqueeze(2) .unsqueeze(3) .to(torch.bool), float("-inf"), ) else: attn_weights = attn_weights.transpose(0, 2) attn_weights = attn_weights.masked_fill(key_padding_mask, float("-inf")) attn_weights = attn_weights.transpose(0, 2) attn_weights = attn_weights.view(bsz * self.num_heads, tgt_len, src_len) if before_softmax: return attn_weights, v attn_weights_float = utils.softmax( attn_weights, dim=-1, onnx_trace=self.onnx_trace ) attn_weights = attn_weights_float.type_as(attn_weights) attn_probs = self.dropout_module(attn_weights) assert v is not None if self.encoder_decoder_attention and bsz != kv_bsz: attn = torch.einsum( "bxhts,bhsd->bxhtd", attn_probs.view( ( kv_bsz, -1, self.num_heads, ) + attn_probs.size()[1:] ), v.view( ( kv_bsz, self.num_heads, ) + v.size()[1:] ), ) attn = attn.reshape((-1,) + attn.size()[-2:]) else: attn = torch.bmm(attn_probs, v) assert list(attn.size()) == [bsz * self.num_heads, tgt_len, self.head_dim] if self.onnx_trace and attn.size(1) == 1: # when ONNX tracing a single decoder step (sequence length == 1) # the transpose is a no-op copy before view, thus unnecessary attn = attn.contiguous().view(tgt_len, bsz, self.embed_dim) else: attn = attn.transpose(0, 1).contiguous().view(tgt_len, bsz, self.embed_dim) attn = self.out_proj(attn) attn_weights: Optional[Tensor] = None if need_weights: attn_weights = attn_weights_float.view( bsz, self.num_heads, tgt_len, src_len ).transpose(1, 0) if not need_head_weights: # average attention weights over heads attn_weights = attn_weights.mean(dim=0) return attn, attn_weights
@staticmethod def _append_prev_key_padding_mask( key_padding_mask: Optional[Tensor], prev_key_padding_mask: Optional[Tensor], batch_size: int, src_len: int, static_kv: bool, ) -> Optional[Tensor]: # saved key padding masks have shape (bsz, seq_len) if prev_key_padding_mask is not None and static_kv: new_key_padding_mask = prev_key_padding_mask elif prev_key_padding_mask is not None and key_padding_mask is not None: new_key_padding_mask = [prev_key_padding_mask.float(), key_padding_mask.float()], dim=1 ) # During incremental decoding, as the padding token enters and # leaves the frame, there will be a time when prev or current # is None elif prev_key_padding_mask is not None: if src_len > prev_key_padding_mask.size(1): filler = torch.zeros( (batch_size, src_len - prev_key_padding_mask.size(1)), device=prev_key_padding_mask.device, ) new_key_padding_mask = [prev_key_padding_mask.float(), filler.float()], dim=1 ) else: new_key_padding_mask = prev_key_padding_mask.float() elif key_padding_mask is not None: if src_len > key_padding_mask.size(1): filler = torch.zeros( (batch_size, src_len - key_padding_mask.size(1)), device=key_padding_mask.device, ) new_key_padding_mask = [filler.float(), key_padding_mask.float()], dim=1 ) else: new_key_padding_mask = key_padding_mask.float() else: new_key_padding_mask = prev_key_padding_mask return new_key_padding_mask
[docs] @torch.jit.export def reorder_incremental_state( self, incremental_state: Dict[str, Dict[str, Optional[Tensor]]], new_order: Tensor, ): """Reorder buffered internal state (for incremental generation).""" input_buffer = self._get_input_buffer(incremental_state) if input_buffer is not None: for k in input_buffer.keys(): input_buffer_k = input_buffer[k] if input_buffer_k is not None: if self.encoder_decoder_attention: if input_buffer_k.size(0) * self.beam_size == new_order.size(0): return incremental_state elif self.beam_size > 1: input_buffer[k] = input_buffer_k.index_select( 0, new_order.reshape(-1, self.beam_size)[:, 0] // self.beam_size, ) else: input_buffer[k] = input_buffer_k.index_select(0, new_order) else: input_buffer[k] = input_buffer_k.index_select(0, new_order) incremental_state = self._set_input_buffer(incremental_state, input_buffer) return incremental_state
[docs] def set_beam_size(self, beam_size): """Used for effiecient beamable enc-dec attention""" self.beam_size = beam_size
def _get_input_buffer( self, incremental_state: Optional[Dict[str, Dict[str, Optional[Tensor]]]] ) -> Dict[str, Optional[Tensor]]: result = self.get_incremental_state(incremental_state, "attn_state") if result is not None: return result else: empty_result: Dict[str, Optional[Tensor]] = {} return empty_result def _set_input_buffer( self, incremental_state: Dict[str, Dict[str, Optional[Tensor]]], buffer: Dict[str, Optional[Tensor]], ): return self.set_incremental_state(incremental_state, "attn_state", buffer)
[docs] def apply_sparse_mask(self, attn_weights, tgt_len: int, src_len: int, bsz: int): return attn_weights
[docs] def upgrade_state_dict_named(self, state_dict, name): prefix = name + "." if name != "" else "" items_to_add = {} keys_to_remove = [] for k in state_dict.keys(): if k.endswith(prefix + "in_proj_weight"): # in_proj_weight used to be q + k + v with same dimensions dim = int(state_dict[k].shape[0] / 3) items_to_add[prefix + "q_proj.weight"] = state_dict[k][:dim] items_to_add[prefix + "k_proj.weight"] = state_dict[k][dim : 2 * dim] items_to_add[prefix + "v_proj.weight"] = state_dict[k][2 * dim :] keys_to_remove.append(k) k_bias = prefix + "in_proj_bias" if k_bias in state_dict.keys(): dim = int(state_dict[k].shape[0] / 3) items_to_add[prefix + "q_proj.bias"] = state_dict[k_bias][:dim] items_to_add[prefix + "k_proj.bias"] = state_dict[k_bias][ dim : 2 * dim ] items_to_add[prefix + "v_proj.bias"] = state_dict[k_bias][2 * dim :] keys_to_remove.append(prefix + "in_proj_bias") for k in keys_to_remove: del state_dict[k] for key, value in items_to_add.items(): state_dict[key] = value