   0  -live- %r1
   3  guard_class %r1 -> %i0
   6  getfield_raw_i %i0, FieldDescr<pypy.interpreter.baseobjspace.W_Root_vtable.cls_itemsize> -> %i0
  11  new_with_vtable <rpython.jit.backend.llsupport.descr.SizeDescr object at 0x000002aa74983ec0> -> %r0
  15  setfield_gc_i %r0, %i0, FieldDescr<pypy.objspace.std.intobject.W_IntObject.inst_intval>
  20  ref_return %r0
