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Message-ID: <AANLkTim-2XE=4MbfDLXkg+jj=P5wj2cVKBHemRHLZn2L@mail.gmail.com>
Date: Mon, 15 Nov 2010 23:07:15 +0100
From: Richard Guenther <richard.guenther@...il.com>
To: Jeff Law <law@...hat.com>
Cc: Andi Kleen <andi@...stfloor.org>,
Andreas Schwab <schwab@...ux-m68k.org>, Jim <jim876@...all.nl>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
gcc@....gnu.org
Subject: Re: gcc 4.5.1 / as 2.20.51.0.11 miscompiling drivers/char/i8k.c ?
On Mon, Nov 15, 2010 at 7:45 PM, Jeff Law <law@...hat.com> wrote:
> On 11/08/10 03:49, Richard Guenther wrote:
>>
>> On Mon, Nov 8, 2010 at 12:03 AM, Andi Kleen<andi@...stfloor.org> wrote:
>>>
>>> Andreas Schwab<schwab@...ux-m68k.org> writes:
>>>>
>>>> The asm fails to mention that it modifies *regs.
>>>
>>> It has a memory clobber, that should be enough, no?
>>
>> No. A memory clobber does not cover automatic storage.
>
> A memory clobber should clobber anything in memory, including autos in
> memory; if it doesn't, then that seems like a major problem. I'd like to
> see the rationale behind not clobbering autos in memory.
Non-address taken automatic storage. (note that we don't excercise this
in optimization yet)
It's difficult to model thins kind of non-aliased memory with this kind
of aliasing mechanism (apart from taking all asms as clobbering
everything as we currently do).
Richard.
> Jeff
>
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