228     list->_gc_next = (uintptr_t)list;  in gc_list_init()
234     return (list->_gc_next == (uintptr_t)list);  in gc_list_is_empty()
262     node->_gc_next = 0; /* object is not currently tracked */  in gc_list_remove()
367     assert((head->_gc_next & NEXT_MASK_UNREACHABLE) == 0);  in validate_list()
389         PyGC_Head *truenext = (PyGC_Head *)(gc->_gc_next  & ~NEXT_MASK_UNREACHABLE);  in validate_list()
393         assert((gc->_gc_next & NEXT_MASK_UNREACHABLE) == next_value);  in validate_list()
495     assert(gc->_gc_next != 0);  in visit_reachable()
497     if (gc->_gc_next & NEXT_MASK_UNREACHABLE) {  in visit_reachable()
507         PyGC_Head *next = (PyGC_Head*)(gc->_gc_next & ~NEXT_MASK_UNREACHABLE);  in visit_reachable()
509                          prev->_gc_next & NEXT_MASK_UNREACHABLE);  in visit_reachable()
511                          next->_gc_next & NEXT_MASK_UNREACHABLE);  in visit_reachable()
512         prev->_gc_next = gc->_gc_next;  // copy NEXT_MASK_UNREACHABLE  in visit_reachable()
599             prev->_gc_next = gc->_gc_next;  in move_unreachable()
609             last->_gc_next = (NEXT_MASK_UNREACHABLE | (uintptr_t)gc);  in move_unreachable()
611             gc->_gc_next = (NEXT_MASK_UNREACHABLE | (uintptr_t)unreachable);  in move_unreachable()
614         gc = (PyGC_Head*)prev->_gc_next;  in move_unreachable()
619     unreachable->_gc_next &= ~NEXT_MASK_UNREACHABLE;  in move_unreachable()
667     assert((unreachable->_gc_next & NEXT_MASK_UNREACHABLE) == 0);  in move_legacy_finalizers()
675         _PyObject_ASSERT(op, gc->_gc_next & NEXT_MASK_UNREACHABLE);  in move_legacy_finalizers()
676         gc->_gc_next &= ~NEXT_MASK_UNREACHABLE;  in move_legacy_finalizers()
677         next = (PyGC_Head*)gc->_gc_next;  in move_legacy_finalizers()
693     assert((unreachable->_gc_next & NEXT_MASK_UNREACHABLE) == 0);  in clear_unreachable_mask()
695         _PyObject_ASSERT((PyObject*)FROM_GC(gc), gc->_gc_next & NEXT_MASK_UNREACHABLE);  in clear_unreachable_mask()
696         gc->_gc_next &= ~NEXT_MASK_UNREACHABLE;  in clear_unreachable_mask()
697         next = (PyGC_Head*)gc->_gc_next;  in clear_unreachable_mask()
866         gc = (PyGC_Head*)wrcb_to_call._gc_next;  in handle_weakrefs()
892         if (wrcb_to_call._gc_next == (uintptr_t)gc) {  in handle_weakrefs()
2232     g->_gc_next = 0;  in _PyObject_GC_Alloc()