Re: gcc 4.5.1 / as 2.20.51.0.11 miscompiling drivers/char/i8k.c ?

[Richard Guenther]

On Mon, Nov 15, 2010 at 7:45 PM, Jeff Law <law@xxxxxxxxxx> wrote:
> On 11/08/10 03:49, Richard Guenther wrote:
>>
>> On Mon, Nov 8, 2010 at 12:03 AM, Andi Kleen<andi@xxxxxxxxxxxxxx>  wrote:
>>>
>>> Andreas Schwab<schwab@xxxxxxxxxxxxxx>  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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