Hi Ömer, These are pointed to by objects traversed by GC. They have info tables like any other heap object that GC can understand. I think this is a much simpler invariant to hold then to have some heap objects point to NULL.
Ryan On Mon, May 7, 2018 at 3:34 PM, Ömer Sinan Ağacan <omeraga...@gmail.com> wrote: > Currently we sometimes use special closures to mark end of lists of > different > objects. Some examples: > > - END_TSO_QUEUE > - END_STM_WATCH_QUEUE > - END_STM_CHUNK_LIST > > But we also use NULL for the same thing, e.g. in weak pointer lists > (old_weak_ptr_list, weak_ptr_list). > > I'm wondering why we need special marker objects (which are actual closures > with info tables) instead of using NULL consistently. Current approach > causes a > minor problem when working on the RTS because every time I traverse a list > I > need to remember how the list is terminated (e.g. NULL when traversing weak > pointer lists, END_TSO_QUEUE when traversing TSO lists). > > Ömer > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >
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