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Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions
From: |
Al Viro |
Subject: |
Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions |
Date: |
Sat, 5 Jul 2014 06:26:07 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Sat, Jul 05, 2014 at 02:40:55AM +0100, Al Viro wrote:
> d) at least on EV6 and EV67 DNOD *still* trips INV. According to the
> manual suppression of INV by DNOD is optional. And while their text
> might be interpreted as "INV is suppressed if operation with denorm
> wouldn't result in something unpleasant" (which would apply to
> sqrt(DBL_MIN/2)), the same behaviour happens on DBL_MIN/2 + DBL_MIN/2,
> where the result is a good finite value, so it really looks like DNOD
> doesn't suppress INV at all on these processors.
>
> Does anybody have 21364 to run some tests on?
In fact, DNOD is simply not implemented on those guys - if you try to set it,
the bit still reads zero. Worse, according to Compiler Writer's Guide for the
21264/21364, "Alpha architecture FPCR bit 47 (DNOD) is not implemented
by the 21264 or 21364".
In other words, it looks like FPCR.DNOD is something from (never-produced)
21464.
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, (continued)
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/03
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/03
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Richard Henderson, 2014/07/03
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/03
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Peter Maydell, 2014/07/03
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/03
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/03
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Richard Henderson, 2014/07/04
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/04
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/04
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions,
Al Viro <=
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/05
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/05
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Richard Henderson, 2014/07/07
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/07
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Richard Henderson, 2014/07/07
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/08
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Richard Henderson, 2014/07/08
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/08
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Al Viro, 2014/07/08
- Re: [Qemu-devel] [RFC] alpha qemu arithmetic exceptions, Peter Maydell, 2014/07/08