GNU bug report logs - #75322
SAFE_ALLOCA assumed to root Lisp_Objects/SSDATA(string)

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Message #59 received at 75322 <at> debbugs.gnu.org (full text, mbox):

From: Gerd Möllmann <gerd.moellmann <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: Pip Cet <pipcet <at> protonmail.com>, 75322 <at> debbugs.gnu.org
Subject: Re: bug#75322: SAFE_ALLOCA assumed to root Lisp_Objects/SSDATA(string)
Date: Sat, 04 Jan 2025 15:13:06 +0100

Eli Zaretskii <eliz <at> gnu.org> writes:

>> IIUC, Gerd explained that the old GC can still move the string *data*
>> used in that structure, even if the string metadata stays in place.
>
> If string data is moved, then accessing the old pointer would trigger
> the barrier and MPS will do its thing, not?
>
> To clarify, I was trying to understand whether the error message
> reported by Ihor in another thread could have happened because of GC
> in this are of the code.

So, Ihor saw something in igc. In that case, the string _data_ will
never a barrier on it, because it's leaf data, i.e. data that doesn't
contain references, and that is allocated from an AMCZ pool. If that
helps, don't know.

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