From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Andreas Schwab <schwab@suse.de>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: bug in arch/ppc/kernel/misc.S: __ashrdi3?
Date: Sun, 17 Jul 2005 04:24:57 +1000 [thread overview]
Message-ID: <1121538297.14393.20.camel@gaston> (raw)
In-Reply-To: <jeackmbped.fsf@sykes.suse.de>
On Sat, 2005-07-16 at 20:02 +0200, Andreas Schwab wrote:
> Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:
>
> > On Fri, 2005-07-15 at 18:01 +0200, Frank van Maarseveen wrote:
> >> I don't really grok the code but an operand seems to be missing and the
> >> assembler makes something out of it I don't trust:
> >>
> >> _GLOBAL(__ashrdi3)
> >> ...
> >> rlwinm r8,r7,0,32 # t3 = (count < 32) ? 32 : 0
> >
> > This is equivalent to r8 = r7 & 32. It will definitely not do what the
> > comment says though. If (count < 64), however, it will do something
> > like r8 = (r7 < 32) ? 0 : 32. Paul, maybe we should dbl check what's
> > going in there ?
>
> r7 is count + 32, and ((count + 32) & 32) is equivalent to the expression
> above if count < 64.
Ok, with some context it makes more sense :)
Ben.
next prev parent reply other threads:[~2005-07-16 18:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-15 16:01 bug in arch/ppc/kernel/misc.S: __ashrdi3? Frank van Maarseveen
2005-07-15 18:22 ` Andreas Schwab
2005-07-16 17:39 ` Benjamin Herrenschmidt
2005-07-16 18:02 ` Andreas Schwab
2005-07-16 18:24 ` Benjamin Herrenschmidt [this message]
2005-07-18 12:14 ` Gabriel Paubert
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