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Re: question about if_marked construct

Tom de Vries <> writes:

> What I am really trying to do, is a bootstrap debug build of 4.3.5.
> However, I ran into bug 31230. I minimized the testcase, did an
> analysis, created a naive patch to test my hypothesis, tested the
> patch and put it in the bug report. Now I'm looking for feedback.
> In the question I asked to this mailing list I tried to abstract away  
>> From the specific case I analyzed, to get a more conceptual  
> discussion about the garbage collector, but maybe that was a mistake,
> sorry for the confusion.
> My analysis, what I'm trying to get confirmed, is that the the actual
> type_hash_marked_p() in gcc is 'such an if_marked property':
> ...
> static int type_hash_marked_p (const void *p) {
>  tree type = ((struct type_hash *) p)->type;
>  return ggc_marked_p (type) || TYPE_SYMTAB_POINTER (type);
> }

Interesting.  My first reaction is that this is an invalid use of the
garbage collector.  I think there is really only one valid function
that can be used as an if_marked function: one which checks
ggc_marked_p on the structure.  The only counterexample I can see in
the current code is this one.  It seems to me that we can work around
this by building a separate garbage collector root pointing to all
types for which TYPE_SYMTAB_POINTER is true.


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