bug#41321: 27.0.91; Emacs aborts due to invalid pseudovector objects

[Pip Cet]

On Sat, May 30, 2020 at 6:57 PM Paul Eggert <eggert@cs.ucla.edu> wrote:
> On 5/30/20 11:39 AM, Pip Cet wrote:
> > I fail to see the problem
> > with my patch. mark_maybe_object is unnecessary on x86
> > --with-wide-int, and mark_maybe_pointer (off + lispsym) is unnecessary
> > on platforms that don't rip apart our precious Lisp_Objects. The other
> > call to mark_maybe_pointer isn't skipped.
>
> The other alloc.c code is inconsistent with respect to the
> live_*_holding versus live_*_p functions. There is no live_float_holding
> function,

Indeed. There's just live_float_p.

> which means we're relying entirely on mark_maybe_object to
> find roots that contain Lisp floats.

No, we're not. There's code in mark_maybe_pointer to handle the float
case, by calling live_float_p.

Is it misaligned pointers into floats you're worried about?

> So it's dicey that your earlier
> (Bug#41321#299) patch skips the call to mark_maybe_object on some platforms.

I still fail to see how.