Subject: Re: bug#30855: 25.3; temacs fails with bus error during garbage collection

From: Andreas Schwab <[email-masked]>
Date: Tue, 20 Mar 2018 16:26:19 +0100

On Mär 20 2018, Eli Zaretskii <[email-masked]> wrote:

> So you are saying that we should be doing the below instead?
>
> diff --git a/src/alloc.c b/src/alloc.c
> index 9d0e2d3..18546ca 100644
> --- a/src/alloc.c
> +++ b/src/alloc.c
> @@ -4983,7 +4983,8 @@ mark_memory (void *start, void *end)
>    for (pp = start; (void *) pp < end; pp += GC_POINTER_ALIGNMENT)
>      {
>        mark_maybe_pointer (*(void **) pp);
> -      mark_maybe_object (*(Lisp_Object *) pp);
> +      if ((intptr_t) pp % GCALIGNMENT == 0)

That should be alignof(Lisp_Object).  A Lisp_Object only needs
Lisp_Object alignment.  GCALIGNMENT is about the _value_ of a
Lisp_Object (ie. the address of the Lisp object that this Lisp_Object
points to).

Andreas.

-- 
Andreas Schwab, SUSE Labs, [email-masked]
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"And now for something completely different."