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From: Eli Zaretskii <eliz@gnu.org>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: rudalics@gmx.at, emacs-devel@gnu.org, rgm@gnu.org
Subject: Re: emacs-26 9e59de9: Use GCALIGNED properly for GCC
Date: Fri, 10 Nov 2017 11:57:58 +0200	[thread overview]
Message-ID: <83shdmpiah.fsf@gnu.org> (raw)
In-Reply-To: <4ee60712-789e-f160-52a9-4e24a9733a11@cs.ucla.edu> (message from Paul Eggert on Fri, 10 Nov 2017 00:26:19 -0800)

> Cc: rgm@gnu.org, emacs-devel@gnu.org
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Fri, 10 Nov 2017 00:26:19 -0800
> 
> I have thought of a solution that fixes the problem by dropping use of GCALIGNED 
> and instead using classic C unions along with 'char alignas (8)'. The idea is to 
> gcalign a 'struct foo' this way:
> 
>     union gcaligned_foo { struct foo s; char alignas (8) gcaligned; };

Wouldn't it be more reliable to use something like

  union gcaligned_foo { struct foo s; int64_t gcaligned; };

IOW, should we rely on alignas?  There could be dragons there too, no?

> Something like this should work on all platforms that Emacs ports to. I plan to 
> work on a first cut tomorrow.

Thanks.



  reply	other threads:[~2017-11-10  9:57 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20171109031206.7056.28312@vcs0.savannah.gnu.org>
     [not found] ` <20171109031208.D2CAF2033E@vcs0.savannah.gnu.org>
2017-11-09 23:31   ` emacs-26 9e59de9: Use GCALIGNED properly for GCC Glenn Morris
2017-11-10  7:10     ` martin rudalics
2017-11-10  8:06       ` Eli Zaretskii
2017-11-10  8:26         ` Paul Eggert
2017-11-10  9:57           ` Eli Zaretskii [this message]
2017-11-10 16:23             ` Stefan Monnier
2017-11-10 17:58               ` Paul Eggert
2017-11-10 18:02                 ` Stefan Monnier
2017-11-10 18:11                   ` Philipp Stephani
2017-11-10 19:19                     ` Paul Eggert
2017-11-10 20:31                       ` Stefan Monnier
2017-11-10 20:45                         ` Paul Eggert
2017-11-11  7:08           ` Paul Eggert
2017-11-11  7:57             ` Paul Eggert
2017-11-11  8:34               ` martin rudalics
2017-11-11  8:50                 ` Paul Eggert
2017-11-11  9:46                   ` martin rudalics
2017-11-11  8:33             ` martin rudalics
2017-11-13 18:19               ` Paul Eggert
2017-11-13 18:45                 ` martin rudalics

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