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Re: [RFC] MIPS division by zero and libgcj...

To: David Daney <ddaney@avtrex.com>
Subject: Re: [RFC] MIPS division by zero and libgcj...
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Fri, 11 Jun 2004 16:01:42 +0200 (CEST)
Cc: gcc@gcc.gnu.org, linux-mips@linux-mips.org, java@gcc.gnu.org
In-reply-to: <40C8B29B.3090501@avtrex.com>
Organization: Technical University of Gdansk
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <40C8B29B.3090501@avtrex.com>
Sender: linux-mips-bounce@linux-mips.org
On Thu, 10 Jun 2004, David Daney wrote:

> It appears that gcc configured for mipsel-linux will execute a "break 7" 
> instruction on integer division by zero.
> 
> This causes the kernel (I am using 2.4.25) to send SIGTRAP.

 It looks like you have a problem in your configuration.  A "break 7"  
(or "teq <divisor>,$zero,7" -- but that's currently implemented in gas
only) is indeed emitted and exectuted in the case of division by zero, but
Linux has the ability to recognize this special break code and sends
SIGFPE instead.  There are actually two special codes defined, the other
being "6" for an overflow.  Both are handled by Linux, with si_code in
struct siginfo being set to FPE_INTDIV or FPE_INTOVF, respectively.  You
can handle this appropriately in a signal handler.

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +

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