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From: Alexander Monakov <amonakov@ispras.ru>
To: "Richard Earnshaw (lists)" <Richard.Earnshaw@arm.com>
Cc: "Paul Koning" <paulkoning@comcast.net>,
	"Markus Fröschle" <markus@mubf.de>,
	gcc@gcc.gnu.org
Subject: Re: asking for __attribute__((aligned()) clarification
Date: Mon, 19 Aug 2019 14:08:00 -0000	[thread overview]
Message-ID: <alpine.LNX.2.20.13.1908191706100.32047@monopod.intra.ispras.ru> (raw)
In-Reply-To: <055f71a6-7b20-eb80-6f0a-d7572c34fa47@arm.com>

On Mon, 19 Aug 2019, Richard Earnshaw (lists) wrote:

> Correct, but note that you can only pack structs and unions, not basic types.
> there is no way of under-aligning a basic type except by wrapping it in a
> struct.

I don't think that's true. In GCC-9 the doc for 'aligned' attribute has been
significantly revised, and now ends with

  When used as part of a typedef, the aligned attribute can both increase and
  decrease alignment, and specifying the packed attribute generates a warning. 

(but I'm sure defacto behavior of accepting and honoring reduced alignment on
a typedef'ed scalar type goes way earlier than gcc-9)

Alexander

  reply	other threads:[~2019-08-19 14:08 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-19 12:46 "Markus Fröschle"
2019-08-19 13:57 ` Paul Koning
2019-08-19 14:01   ` Richard Earnshaw (lists)
2019-08-19 14:08     ` Alexander Monakov [this message]
2019-08-19 14:12       ` Paul Koning
2019-08-20  5:46       ` Aw: " "Markus Fröschle"
2019-08-21 14:29         ` Alexander Monakov
2019-08-21 14:32           ` Paul Koning
2019-08-21 14:58             ` Alexander Monakov
2019-08-21 16:50               ` Paul Koning
2019-08-21 17:35                 ` Jonathan Wakely

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