From: Richard Guenther <richard.guenther@gmail.com>
To: "Paweł Sikora" <pluto@agmk.net>
Cc: gcc@gcc.gnu.org
Subject: Re: (un)aligned accesses on x86 platform.
Date: Mon, 08 Mar 2010 15:46:00 -0000 [thread overview]
Message-ID: <84fc9c001003080746p775b14b4s105ed0ddbf4a2fb1@mail.gmail.com> (raw)
In-Reply-To: <op.u889o5kpzu3k57@pawels.alatek.krakow.pl>
2010/3/8 Paweł Sikora <pluto@agmk.net>:
> hi,
>
> during development a cross platform appliacation on x86 workstation
> i've enabled an alignemnt checking [1] to catch possible erroneous
> code before it appears on client's sparc/arm cpu with sigbus ;)
>
> it works pretty fine and catches alignment violations but Jakub Jelinek
> had told me (on glibc bugzilla) that gcc on x86 can still dereference
> an unaligned pointer (except for vector insns).
> i suppose it means that gcc can emit e.g. movl for access a short int
> (or maybe others scenarios) in some cases and violates cpu alignment rules.
>
> so, is it possible to instruct gcc-x86 to always use suitable loads/stores
> like on sparc/arm?
Only by re-building it and setting STRICT_ALIGNMENT.
Richard.
> [1] "AC" bit - http://en.wikipedia.org/wiki/FLAGS_register_(computing)
>
> BR,
> Pawel.
>
next prev parent reply other threads:[~2010-03-08 15:46 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-08 15:37 Paweł Sikora
2010-03-08 15:45 ` Andrew Pinski
2010-03-08 15:46 ` Richard Guenther [this message]
2010-03-08 21:11 ` Paweł Sikora
2010-03-16 15:05 ` H.J. Lu
2010-03-16 15:11 ` Tristan Gingold
2010-03-16 15:48 ` Alexey Salmin
2010-03-16 16:02 ` Tristan Gingold
2010-03-16 16:08 ` Alexey Salmin
2010-03-16 16:16 ` Piotr Wyderski
2010-03-16 18:31 ` Jakub Jelinek
2010-03-17 15:43 ` Mikael Pettersson
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