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From: David Daney <ddaney@avtrex.com>
To: Thiemo Seufer <ica2_ts@csv.ica.uni-stuttgart.de>
Cc: Ralf Baechle <ralf@linux-mips.org>,
	"Maciej W. Rozycki" <macro@ds2.pg.gda.pl>,
	linux-mips@linux-mips.org
Subject: Re: [patch] Prevent dead code/data removal with gcc 3.4
Date: Fri, 13 Feb 2004 14:35:43 -0800	[thread overview]
Message-ID: <402D513F.8080205@avtrex.com> (raw)
In-Reply-To: <20040213222253.GA20118@rembrandt.csv.ica.uni-stuttgart.de>

Thiemo Seufer wrote:

>Ralf Baechle wrote:
>  
>
>>On Fri, Feb 13, 2004 at 03:20:27PM +0100, Maciej W. Rozycki wrote:
>>
>>    
>>
>>>2. It changes inline-assembly function prologues to be embedded within the
>>>functions, which makes them a bit safer as they can now explicitly refer
>>>to the "regs" struct and assures the code won't be removed or reordered.
>>>      
>>>
>>It is possible that gcc changes one of the registers before save_static
>>and I can't imagine there's a reliable way to fix this in the inline
>>version.
>>    
>>
>
>As long as __asm__ __volatile__ works as documented, this can't happen.
>  
>
My understanding is that with gcc-3.4 that __asm__ __volatile__ does not 
protect against dead code removal.  If the code is not dead __volatile__ 
works as documented, but dead code removal still happens.

David Daney.

  reply	other threads:[~2004-02-13 22:35 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-02-13 14:20 [patch] Prevent dead code/data removal with gcc 3.4 Maciej W. Rozycki
2004-02-13 14:53 ` Ralf Baechle
2004-02-13 17:51   ` Jun Sun
2004-02-13 18:35     ` Maciej W. Rozycki
2004-02-13 22:07       ` Ralf Baechle
2004-02-16  9:18         ` Maciej W. Rozycki
2004-02-13 22:22   ` Thiemo Seufer
2004-02-13 22:35     ` David Daney [this message]
2004-02-13 22:50       ` Thiemo Seufer
2004-02-14  1:15         ` Ralf Baechle
2004-02-14  1:22           ` Eric Christopher
2004-02-14  1:28           ` Thiemo Seufer
2004-02-14  1:45             ` Ralf Baechle
2004-02-14  2:17               ` Thiemo Seufer
2004-02-14  6:13                 ` Jun Sun
2004-02-14  6:28                   ` Thiemo Seufer
2004-02-15  1:44                     ` Daniel Jacobowitz
2004-02-17 12:50         ` Maciej W. Rozycki
2004-06-28 13:12   ` Maciej W. Rozycki

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