Re: Emacs-26 threads problem [win64]

[Eli Zaretskii <eliz@gnu.org>]

> From: Andreas Schwab <schwab@linux-m68k.org>
> Cc: Eli Zaretskii <eliz@gnu.org>,  fabrice.popineau@gmail.com,  emacs-devel@gnu.org
> Date: Sat, 14 Oct 2017 11:30:07 +0200
> 
> On Okt 14 2017, Paul Eggert <eggert@cs.ucla.edu> wrote:
> 
> > Eli Zaretskii wrote:
> >> What is special about this specific struct that it needs such an
> >> alignment?
> >
> > The answer to this question is MS-Windows specific, and I don't know
> > exactly which member of struct thread_state requires 16-byte alignment. I
> > just know it's in there somewhere....
> 
> Obvious candidates are sys_thread_t and sys_cond_t, of course.

Can you explain why?  E.g., with pthreads, sys_thread_t is pthread_t,
which AFAIU is the same width as 'int', in which case it won't force
any 16-byte alignment anywhere.

Also, all the members which have the sys_thread_t and sys_cond_t types
are after the problematic members in the struct offset order, so how
can they affect the alignment of the problematic members or of the
struct itself?

Thanks.