   0  -live- %r1, %r2
   0  goto_if_not_ptr_nonzero %r1, L1
   4  ref_copy %r1 -> %r0
   7  -live- %r0, %r1, %r2
   7  guard_class %r1 -> %i0
  10  -live- %i0, %r0, %r2
  10  goto_if_not_int_eq %i0, $<* struct object_vtable>, L2
  15  residual_call_r_v $<* fn W_Dtype.descr_set_names>, R[%r0, %r2], <CallDescr(rr) EF=7>
  22  -live-
  22  void_return
  23  ---
  23  L2:
  23  raise $<* struct object>
  25  ---
  25  L1:
  25  raise $<* struct object>
