   0  -live- %r1
   0  guard_class %r1 -> %i0
   3  getfield_raw_i %i0, FieldDescr<pypy.interpreter.baseobjspace.W_Root_vtable.cls_itemsize> -> %i0
   8  new_with_vtable <rpython.jit.backend.llsupport.descr.SizeDescr object at 0x100951d1e10> -> %r0
  12  setfield_gc_i %r0, %i0, FieldDescr<pypy.objspace.std.intobject.W_IntObject.inst_intval>
  17  ref_return %r0
