From: Joseph Myers <joseph@codesourcery.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: <gcc-patches@gcc.gnu.org>, <eggert@cs.ucla.edu>
Subject: Re: Make max_align_t respect _Float128 [version 2]
Date: Tue, 06 Sep 2016 15:20:00 -0000 [thread overview]
Message-ID: <alpine.DEB.2.20.1609061512080.19423@digraph.polyomino.org.uk> (raw)
In-Reply-To: <3bb7530e-fff4-6030-a87e-1654d55d1e45@redhat.com>
On Tue, 6 Sep 2016, Florian Weimer wrote:
> So that's what ties the two things together. I still don't like what's
> implied in PR66661, that all object sizes have to be multiples of the
> fundamental alignment.
I don't think there's any such requirement in the case of flexible array
members; if you use malloc to allocate a structure with a flexible array
member, you can access as many trailing array elements as would fit within
the allocated size, whether or not that size is a multiple of either the
alignment of the structure, or the alignment of max_align_t.
> > Well, that's a conformance bug in the implementation as a whole. The
> > nonconforming modes in question are still useful and it's useful for GCC
> > to support such mallocs.
>
> PR66661 shows that GCC does not want to support such mallocs (or even glibc's
> malloc).
GCC is supposed to support all mallocs that produce results aligned to at
least MALLOC_ABI_ALIGNMENT (which may be smaller than the alignment of
max_align_t).
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2016-09-06 15:16 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-26 20:55 Make max_align_t respect _Float128 Joseph Myers
2016-08-26 21:10 ` Marc Glisse
2016-08-26 21:30 ` Joseph Myers
2016-08-26 21:45 ` Florian Weimer
2016-08-26 21:57 ` Paul Eggert
2016-08-26 22:25 ` Joseph Myers
2016-08-26 21:51 ` Paul Eggert
2016-08-29 13:29 ` Marek Polacek
2016-08-29 15:40 ` Joseph Myers
2016-09-01 14:18 ` Ping " Joseph Myers
2016-09-05 17:07 ` Make max_align_t respect _Float128 [version 2] Joseph Myers
2016-09-06 9:06 ` Richard Biener
2016-09-06 11:26 ` Joseph Myers
2016-09-06 9:19 ` Florian Weimer
2016-09-06 9:24 ` Richard Biener
2016-09-07 7:45 ` Florian Weimer
2016-09-07 17:53 ` Joseph Myers
2016-09-08 9:35 ` Florian Weimer
2016-09-06 11:40 ` Joseph Myers
2016-09-06 15:06 ` Florian Weimer
2016-09-06 15:20 ` Joseph Myers [this message]
2016-09-06 15:59 ` Paul Eggert
2016-09-06 20:47 ` Joseph Myers
2016-09-06 21:41 ` Paul Eggert
2016-09-07 9:22 ` Florian Weimer
2016-09-07 11:52 ` Mark Wielaard
2016-09-08 1:58 ` Paul Eggert
2016-09-08 11:58 ` Mark Wielaard
2016-09-08 12:22 ` Florian Weimer
2016-09-08 14:59 ` Paul Eggert
2016-09-08 12:30 ` Bernd Schmidt
2016-09-08 12:34 ` Florian Weimer
2016-09-07 9:15 ` Florian Weimer
2016-09-06 21:03 ` Jason Merrill
2016-09-06 21:18 ` Joseph Myers
2016-09-06 21:53 ` Jason Merrill
2016-09-06 21:56 ` Joseph Myers
2016-09-06 12:06 ` Bernd Schmidt
2016-09-06 14:59 ` Florian Weimer
2016-09-12 18:02 ` Make max_align_t respect _Float128 [version 3] Joseph Myers
2016-09-19 16:08 ` Ping " Joseph Myers
2016-09-19 17:11 ` Paul Eggert
2016-09-26 16:35 ` Jeff Law
2016-09-06 18:14 Make max_align_t respect _Float128 [version 2] Bernd Edlinger
2016-09-06 20:58 ` Joseph Myers
2016-09-07 19:50 Bernd Edlinger
2016-09-07 20:06 ` Joseph Myers
2016-09-07 21:00 ` Bernd Edlinger
2016-09-07 21:48 ` Joseph Myers
2016-09-08 10:50 ` Florian Weimer
2016-09-09 17:24 ` Bernd Edlinger
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