From: Gabriel Paubert <paubert@iram.es>
To: Andreas Schwab <schwab@linux-m68k.org>
Cc: gcc-help@gcc.gnu.org, kernel mailz <kernelmailz@googlemail.com>,
linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org
Subject: Re: Inline assembly queries [2]
Date: Mon, 6 Jul 2009 08:56:27 +0200 [thread overview]
Message-ID: <20090706065627.GA12499@iram.es> (raw)
In-Reply-To: <m23a9deb87.fsf@igel.home>
On Fri, Jul 03, 2009 at 10:57:12PM +0200, Andreas Schwab wrote:
> Brad Boyer <flar@allandria.com> writes:
>
> > On Fri, Jul 03, 2009 at 12:14:41PM +0530, kernel mailz wrote:
> >> b. using m or Z with a memory address. I tried replacing m/Z but no change
> >> Is there some guideline ?
> >> gcc documentation says Z is obsolete. Is m/Z replaceable ?
> >
> > No idea. I don't remember ever seeing 'Z' used in anything. Maybe somebody
> > else remembers what it used to mean.
>
> The 'Z' constraint is required for a memory operand for insns that don't
> have an update form (which would be selected by the %U modifier).
Hmmm, I believed that it was for instructions that only have an indexed
form (all Altivec, byte reverse, and l?arx/st?cx for atomic operations).
Of course none of these instructions have an update form, but they don't
have an offset encoded in the instruction either.
Gabriel
WARNING: multiple messages have this Message-ID (diff)
From: Gabriel Paubert <paubert@iram.es>
To: Andreas Schwab <schwab@linux-m68k.org>
Cc: Brad Boyer <flar@allandria.com>,
gcc-help@gcc.gnu.org, linuxppc-dev@ozlabs.org,
linux-kernel@vger.kernel.org,
kernel mailz <kernelmailz@googlemail.com>
Subject: Re: Inline assembly queries [2]
Date: Mon, 6 Jul 2009 08:56:27 +0200 [thread overview]
Message-ID: <20090706065627.GA12499@iram.es> (raw)
In-Reply-To: <m23a9deb87.fsf@igel.home>
On Fri, Jul 03, 2009 at 10:57:12PM +0200, Andreas Schwab wrote:
> Brad Boyer <flar@allandria.com> writes:
>
> > On Fri, Jul 03, 2009 at 12:14:41PM +0530, kernel mailz wrote:
> >> b. using m or Z with a memory address. I tried replacing m/Z but no change
> >> Is there some guideline ?
> >> gcc documentation says Z is obsolete. Is m/Z replaceable ?
> >
> > No idea. I don't remember ever seeing 'Z' used in anything. Maybe somebody
> > else remembers what it used to mean.
>
> The 'Z' constraint is required for a memory operand for insns that don't
> have an update form (which would be selected by the %U modifier).
Hmmm, I believed that it was for instructions that only have an indexed
form (all Altivec, byte reverse, and l?arx/st?cx for atomic operations).
Of course none of these instructions have an update form, but they don't
have an offset encoded in the instruction either.
Gabriel
next prev parent reply other threads:[~2009-07-06 6:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-03 6:44 Inline assembly queries [2] kernel mailz
2009-07-03 17:40 ` Brad Boyer
2009-07-03 17:40 ` Brad Boyer
2009-07-03 20:05 ` kernel mailz
2009-07-03 20:05 ` kernel mailz
2009-07-03 21:19 ` Andreas Schwab
2009-07-03 21:19 ` Andreas Schwab
2009-07-03 20:57 ` Andreas Schwab
2009-07-03 20:57 ` Andreas Schwab
2009-07-06 6:56 ` Gabriel Paubert [this message]
2009-07-06 6:56 ` Gabriel Paubert
2009-07-07 12:40 ` Andreas Schwab
2009-07-07 12:40 ` Andreas Schwab
2009-07-07 13:46 ` Gabriel Paubert
2009-07-07 13:46 ` Gabriel Paubert
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