From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([140.186.70.92]:60427)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <jakub@jermar.eu>) id 1QceRO-0004dk-TB
	for qemu-devel@nongnu.org; Fri, 01 Jul 2011 10:11:36 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <jakub@jermar.eu>) id 1QceRM-0007QI-L4
	for qemu-devel@nongnu.org; Fri, 01 Jul 2011 10:11:30 -0400
Received: from mx2.avast.com ([91.213.143.6]:48160)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <jakub@jermar.eu>) id 1QceRM-0007K6-2P
	for qemu-devel@nongnu.org; Fri, 01 Jul 2011 10:11:28 -0400
Message-ID: <4E0DD58C.2070001@jermar.eu>
Date: Fri, 01 Jul 2011 16:11:24 +0200
From: Jakub Jermar <jakub@jermar.eu>
MIME-Version: 1.0
References: <4E0CE6A7.10901@jermar.eu>	<CACXAS8DixKjzQxrjDGwj-xzs9ZxN=O9P=sqN5d9Htx7PNngtNA@mail.gmail.com>	<4E0D9527.7010106@jermar.eu>	<CACXAS8B8E=z0w9fTzO_ZGzh91V5iGFiw_Hb5E=joip1D0=f9=g@mail.gmail.com>
	<4E0DC450.4000700@jermar.eu>
In-Reply-To: <4E0DC450.4000700@jermar.eu>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [HelenOS-devel] [sparc64] Miscomputed minimum of a
 group of numbers in sparc64 emulation
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: HelenOS development mailing list <helenos-devel@lists.modry.cz>
Cc: qemu-devel@nongnu.org

On 1.7.2011 14:57, Jakub Jermar wrote:
> On 1.7.2011 12:41, Artyom Tarasenko wrote:
>> Looks like it's a pretty nice test case.
>>
>> The test case scenario is to load the initial values into the
>> registers (you already know them),
>> calculate the mins, cmp the result with expected and jump somewhere.
>> Since it happens with interrupts disabled, we don't need an OS or bios
>> to test that. The binary just has to have an entry point at 0x20,
>> then we can load it instead of bios.
>>
>> Care to produce the test case? (Otherwise I'll do it, but probably not
>> until the weekend after the next one).
> 
> Yes I have a small reproducible testcase, see the attachments.

Actually, the testcase can be further reduced into:

.global _start

.text

.space 0x20

_start:
	set 110393, %i1
	set 0x40, %i2

	cmp  %i1, %i2
	udivx  %g0, 1, %g0
	movgu  %xcc, %i2, %i1
	cmp  %i1, 512
	bgu  %xcc, 0f
	nop

succ:
	ta 0

fail:
0:
	ta 1

The presence of the `udivx` instruction seems to be essential. Even
though it has no effect on the computation, removing it will make the
testcase non-reproducible.

Jakub