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

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Message-ID: <4CE17DDE.8050207@xs4all.nl>
Date:	Mon, 15 Nov 2010 19:37:18 +0100
From:	Jim Bos <jim876@...all.nl>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Jakub Jelinek <jakub@...hat.com>, Andi Kleen <andi@...stfloor.org>,
	James Cloos <cloos@...loos.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andreas Schwab <schwab@...hat.com>,
	Michael Matz <matz@...e.de>,
	Dave Korn <dave.korn.cygwin@...il.com>,
	Richard Guenther <richard.guenther@...il.com>, gcc@....gnu.org
Subject: Re: gcc 4.5.1 / as 2.20.51.0.11 miscompiling drivers/char/i8k.c ?

On 11/15/2010 07:30 PM, Jim Bos wrote:
> On 11/15/2010 07:08 PM, Linus Torvalds wrote:
>> On Mon, Nov 15, 2010 at 9:40 AM, Jim Bos <jim876@...all.nl> wrote:
>>>
>>> Hmm, that doesn't work.
>>>
>>> [ Not sure if you read to whole thread but initial workaround was to
>>> change the asm(..) to asm volatile(..) which did work. ]
>>
>> Since I have a different gcc than yours (and I'm not going to compile
>> my own), have you posted your broken .s file anywhere? In fact, with
>> the noinline (and the removal of the "+m" thing - iow just the patch
>> you tried), what does just the "i8k_smm" function assembly look like
>> for you after you've done a "make drivers/char/i8k.s"?
>>
>> If the asm just doesn't exist AT ALL, that's just odd. Because every
>> single call-site of i8k_smm() clearly looks at the return value. So
>> the volatile really shouldn't make any difference from that
>> standpoint. Odd.
>>
>>                        Linus
>>
> 
> Attached version with plain 2.6.36 source and version with the committed
> patch, i.e with the '"+m" (*regs)'
> 
> 
> _
> Jim
> 
> 

And I just tried with your noninline patch which results in exactly the
same .s file as with plain 2.6.36 source, i.e. the noninline patch is
not doing anything here.

_
Jim


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