Re: MS-Windows tester wanted for trunk

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 16 Sep 2014 19:46:27 +0400
> From: Dmitry Antipov <dmantipov@yandex.ru>
> CC: emacs-devel@gnu.org
> 
> On 09/16/2014 06:31 PM, Eli Zaretskii wrote:
> 
> > So, as suggested by that page, I marked the callback functions in
> > w32font.c with '__attribute__((force_align_arg_pointer))', and then
> > Emacs comes up normally.  This attribute is available in GCC since
> > v4.2.
> 
>  From GCC manual, as of 4.8:
> 
> -mstackrealign
> 
> Realign the stack at entry.

That's the other solution suggested by the URL I cited.  But it's too
expensive: it adds the realignment overhead to _every_ function call.
By contrast, the number of callback functions we have is quite small,
and even if we decorate all of them with force_align_arg_pointer
(which isn't strictly necessary, AFAIU, since most of them don't cons
Lisp data), that's just a handful of functions that are not
performance-critical.

Is it possible to prevent this problem by using an intermediate local
variable with a suitable alignment (sorry if this is a silly question,
but I have only a very vague idea about alignment).