From mboxrd@z Thu Jan  1 00:00:00 1970
X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/7095
Path: news.gmane.org!not-for-mail
From: Rich Felker <dalias@libc.org>
Newsgroups: gmane.linux.lib.musl.general
Subject: Re: Draft of improved memset.s for i386
Date: Mon, 23 Feb 2015 22:18:11 -0500
Message-ID: <20150224031811.GH23507@brightrain.aerifal.cx>
References: <20150224010952.GA10683@brightrain.aerifal.cx>
 <CAK1hOcN0EaHwzH+LdnNntM1=3-rnHY-hotY1RBD0xB0qeb1SxQ@mail.gmail.com>
 <CAK1hOcO-YYjtPvgJO_DwfE0_t+EwYSxc4T+129Cg2i9sQAYh6A@mail.gmail.com>
Reply-To: musl@lists.openwall.com
NNTP-Posting-Host: plane.gmane.org
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Trace: ger.gmane.org 1424747917 9687 80.91.229.3 (24 Feb 2015 03:18:37 GMT)
X-Complaints-To: usenet@ger.gmane.org
NNTP-Posting-Date: Tue, 24 Feb 2015 03:18:37 +0000 (UTC)
Cc: musl <musl@lists.openwall.com>
To: Denys Vlasenko <vda.linux@googlemail.com>
Original-X-From: musl-return-7108-gllmg-musl=m.gmane.org@lists.openwall.com Tue Feb 24 04:18:36 2015
Return-path: <musl-return-7108-gllmg-musl=m.gmane.org@lists.openwall.com>
Envelope-to: gllmg-musl@m.gmane.org
Original-Received: from mother.openwall.net ([195.42.179.200])
	by plane.gmane.org with smtp (Exim 4.69)
	(envelope-from <musl-return-7108-gllmg-musl=m.gmane.org@lists.openwall.com>)
	id 1YQ615-00046P-Ne
	for gllmg-musl@m.gmane.org; Tue, 24 Feb 2015 04:18:35 +0100
Original-Received: (qmail 21565 invoked by uid 550); 24 Feb 2015 03:18:34 -0000
Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm
Precedence: bulk
List-Post: <mailto:musl@lists.openwall.com>
List-Help: <mailto:musl-help@lists.openwall.com>
List-Unsubscribe: <mailto:musl-unsubscribe@lists.openwall.com>
List-Subscribe: <mailto:musl-subscribe@lists.openwall.com>
Original-Received: (qmail 21520 invoked from network); 24 Feb 2015 03:18:29 -0000
Content-Disposition: inline
In-Reply-To: <CAK1hOcO-YYjtPvgJO_DwfE0_t+EwYSxc4T+129Cg2i9sQAYh6A@mail.gmail.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
Original-Sender: Rich Felker <dalias@aerifal.cx>
Xref: news.gmane.org gmane.linux.lib.musl.general:7095
Archived-At: <http://permalink.gmane.org/gmane.linux.lib.musl.general/7095>

On Tue, Feb 24, 2015 at 04:06:06AM +0100, Denys Vlasenko wrote:
> On Tue, Feb 24, 2015 at 4:02 AM, Denys Vlasenko
> <vda.linux@googlemail.com> wrote:
> > On Tue, Feb 24, 2015 at 2:09 AM, Rich Felker <dalias@libc.org> wrote:
> >>   mov %edi,12(%esp)
> >
> > Shouldn't this be "mov 12(%esp),%edi"?
> > It's a load of dst pointer from stack, right?
> 
> Erm... no it is not, 12(%esp) is size param.
> 
> Looks like this insn serves no purpose?
> This will simply trash size param on stack,
> since %edi is not initialized.

The purpose is saving %edi, since %edi is not call-clobbered on the
i386 ABI. I'm just storing it over top of an argument we already
loaded (argument space belongs to the callee per the ABI) instead of
adjusting the stack pointer.

Rich