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Date: Wed, 2 Jul 2014 16:20:27 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
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Sender: Al Viro <viro@ftp.linux.org.uk>
Subject: Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions
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To: Richard Henderson <rth@twiddle.net>
Cc: Peter Maydell <peter.maydell@linaro.org>, QEMU Developers <qemu-devel@nongnu.org>

> I'm interested in the results of the following test.


DS10:
/su  : 1/3           -i---
/sui : 1/3           -i---
/su  : min*min       -i--u
/sui : min*min       -i--u
/    : (long)4.5     -i---
/sv  : (long)4.5     -i---
/svi : (long)4.5     -i---
/    : (long)max     -i---
/sv  : (long)max     -iI--
/svi : (long)max     -iI--

AS200:
/su  : 1/3           -----
/sui : 1/3           -----
/su  : min*min       -i--u
/sui : min*min       -i--u
/    : (long)4.5     -----
/sv  : (long)4.5     -----
/svi : (long)4.5     -----
/    : (long)max     -----
/sv  : (long)max     --I--
/svi : (long)max     --I--

qemu:
/su  : 1/3           -i---
/sui : 1/3           -i---
/su  : min*min       -i--u
/sui : min*min       -i--u
/    : (long)4.5     -i---
/sv  : (long)4.5     -i---
/svi : (long)4.5     -i---
/    : (long)max     -i---
/sv  : (long)max     -iI--
/svi : (long)max     -iI--

IOW, same as EV6.  The difference is due to the kernel trusting FPCR.INE
as source for FE_INEXACT when it sees implver() returning 2.  See a bit
upthread for analysis...