   0  residual_call_r_r $<* fn _IFilterBase.next_w>, R[%r0], <CallDescr(r) EF=7> -> %r0
   7  -live- %r0
  10  goto_if_not_ptr_iszero %r0, L1
  14  ref_return $<* struct pypy.interpreter.baseobjspace.W_Root>
  16  ---
  16  L1:
  16  ref_return %r0
