Re: MPS: staticpro everything

[Eli Zaretskii <eliz@gnu.org>]

> From: Gerd Möllmann <gerd.moellmann@gmail.com>
> Cc: Helmut Eller <eller.helmut@gmail.com>,  emacs-devel@gnu.org
> Date: Thu, 02 May 2024 11:04:43 +0200
> 
> > Given this, what would be the best way of making sure the 'struct
> > window' pointer in each bidi_it remains valid?  The simplest idea that
> > comes to my mind is to arrange for the window on which redisplay works
> > to be unmovable.  Would that solve the problem?  If so, we could do
> > that in init_iterator, which starts the display iteration process, and
> > I can suggest a patch if you tell me how to do that with MPS.  (I
> > actually think that making the window being redisplayed unmovable is a
> > Good Thing for other reasons, since it frees us from worrying about
> > passing the 'struct window' pointer around, which we do liberally.)
> 
> I would propose to use igc_xzalloc_ambig + igc_free in the MPS case
> instead of xmalloc/xfree. There are also realloc, and palloc variants,
> if you use that.
> 
> This is the same as the normal malloc/free, but it also adds an ambig
> root, so that anything references from the malloc'd memory becomes
> immovable / doesn't die. It's the same as if that memory would be part
> of the control stack.

But doesn't that mean MPS will need to trace too much?

Also, does the above mean my idea of making the window unmovable is
not good?  If so, can you explain why not?