code: def backward(cls, ctx, dx5):
      x, w1, w2, w3, x1, x2 = ctx.saved_tensors
      w1w2 = stack_or_none([w1, w2], dim=0)
  
      dx4 = dx5 @ w3  # 255us (nn)
      dx1dx2, x4 = torch.ops.xformers.silu_bw_fused(x1, x2, dx4)
      dx1, dx2 = dx1dx2.unbind(1)
      del x1, x2, dx4
  
      dw3, db3 = cls._linear_bw(dx5, x4, bias=ctx.bias[2])
      del x4, dx5
      if w1w2 is not None:
          assert dx1dx2.is_contiguous()
          assert w1w2.is_contiguous()
          w1w2 = w1w2.view([w1.shape[0] * 2, w1.shape[1]])
          dx = dx1dx2.view([dx1.shape[0], 2 * dx1.shape[1]]) @ w1w2
  
          # backward of linear1 + linear2 - packed
          dw1dw2 = (
              dx1dx2.view([dx1.shape[0], 2 * dx1.shape[1]]).transpose(
                  -2, -1
              )
              @ x
          )
          dw1dw2, db1db2 = cls._linear_bw(
              dx1dx2.view([dx1.shape[0], 2 * dx1.shape[1]]),
              x,
              bias=ctx.bias[0],
          )
          dw1, dw2 = dw1dw2.view([2, *w1.shape]).unbind(0)
          if ctx.bias[0]:
              db1db2 = db1db2.view([2, dx1.shape[1]])
              db1, db2 = torch.unbind(db1db2, dim=0)
          else:
              db1 = db2 = None
      else:
          dx = dx2 @ w2  # 260us (nn)
          torch.addmm(
              dx, dx1, w1.to(dx1.dtype), beta=1, alpha=1, out=dx
          )  # dx += dx1 @ w1
          dw2, db2 = cls._linear_bw(dx2, x, bias=ctx.bias[1])
          dw1, db1 = cls._linear_bw(dx1, x, bias=ctx.bias[0])
      return (dx, dw1, db1, dw2, db2, dw3, db3)
  
imports: from dataclasses import dataclass
  from typing import Dict, Optional, Sequence, Tuple, Union
  import torch
  import torch.nn.functional
  from torch import nn
  from .common import BaseOperator, get_xformers_operator, register_operator
  from .unbind import stack_or_none, unbind
label_desc: Use image node_id 3 for calling the _SwiGLUFusedFunc obj's underlying member method code with example usage: obj.backward(cls, ctx, dx5) and returns: dx,  dw1,  db1,  dw2,  db2,  dw3,  db3