fix the device bug of the local attention

egs/mustc/st/local/monitor.sh

 gpu_num=1
-cmd=""
+cmd="sh train.sh"
 
 while :
 do

fairseq/modules/local_multihead_attention.py

@@ -319,22 +319,21 @@ class LocalMultiheadAttention(nn.Module):
             x2 = torch.arange(-1, src_len - 1, 1).view(1, -1)
             dis = x2 - x1
             mask_diag = torch.abs(dis) > hard_mask_window
-            mask_diag = mask_diag.unsqueeze(0)
+            mask_diag = mask_diag.unsqueeze(0).to(attn_weights.device)
             attn_weights = attn_weights.masked_fill(mask_diag, float("-inf"))
 
         if self.multihead_gauss_mask_sigma is not None:
-            x1 = torch.arange(-1, src_len - 1, 1).view(-1, 1)
-            x2 = torch.arange(-1, src_len - 1, 1).view(1, -1)
-            diag_growing = -(x1 - x2) ** 2 / 2.0
-            e_diag_gauss_mask = diag_growing.unsqueeze(0).repeat(self.num_heads, 1, 1)
-
-            e_sigma_square = 1 / torch.square(self.multihead_gauss_mask_sigma)
-            e_diag_gauss_mask_final = e_diag_gauss_mask * e_sigma_square
+            x1 = torch.arange(-1, src_len - 1, 1).view(-1, 1).to(attn_weights.device)
+            x2 = torch.arange(-1, src_len - 1, 1).view(1, -1).to(attn_weights.device)
+            dis_square = -(x1 - x2) ** 2 / 2.0
+            multihead_dis_square = dis_square.unsqueeze(0).repeat(self.num_heads, 1, 1)
+            sigma_square = 1 / torch.square(self.multihead_gauss_mask_sigma)
+            gauss_bias = multihead_dis_square * sigma_square
+            gauss_bias = torch.unsqueeze(gauss_bias, 0)
 
-            e_diag_gauss_mask_final = torch.unsqueeze(e_diag_gauss_mask_final, 0)
             attn_weights = attn_weights.view(bsz, self.num_heads, tgt_len, src_len)
             multihead_mask_weight = torch.sigmoid(self.multihead_mask_weight.unsqueeze(0))
-            attn_weights = (1 - multihead_mask_weight) * attn_weights + multihead_mask_weight * e_diag_gauss_mask_final
+            attn_weights = (1 - multihead_mask_weight) * attn_weights + multihead_mask_weight * gauss_bias
             attn_weights = attn_weights.view(bsz * self.num_heads, tgt_len, src_len)
 
         if attn_mask is not None: