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From: Ralf Baechle <ralf@linux-mips.org>
To: Thiemo Seufer <ica2_ts@csv.ica.uni-stuttgart.de>
Cc: David Daney <ddaney@avtrex.com>,
	"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: Sat, 14 Feb 2004 02:45:20 +0100	[thread overview]
Message-ID: <20040214014520.GA4588@linux-mips.org> (raw)
In-Reply-To: <20040214012801.GC20118@rembrandt.csv.ica.uni-stuttgart.de>

On Sat, Feb 14, 2004 at 02:28:01AM +0100, Thiemo Seufer wrote:

> > It's the gcc generated function epilogue which is the problem.  There's
> > no reliable way to work around that ...
> 
> ITYM prologue. It has to follow the ABI specification, so $fp is the only
> possibly problematic one, and that's excluded by -fomit-frame-pointers.

Daniel Jacobowitz reported the problem which indeed was about $30.  Since
the kernel uses -fomit-frame-pointer by default (and -O1 enables it
by default on MIPS anyway) I would assume his kernel was built using that
option.  Maybe he can elaborate ...

Anyway, gcc could load next weeks lucky lottery numbers into the
s-registers after saving them.  That'd break save_static but not the
ABI which only promises to restore the old values in s-registers on
return.

  Ralf

  reply	other threads:[~2004-02-14  1:46 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
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 [this message]
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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