From owner-freebsd-arch  Mon Jul  9  5:11:55 2001
Delivered-To: freebsd-arch@freebsd.org
Received: from mailman.zeta.org.au (mailman.zeta.org.au [203.26.10.16])
	by hub.freebsd.org (Postfix) with ESMTP id 733DC37B405
	for <arch@FreeBSD.ORG>; Mon,  9 Jul 2001 05:11:52 -0700 (PDT)
	(envelope-from bde@zeta.org.au)
Received: from bde.zeta.org.au (bde.zeta.org.au [203.2.228.102])
	by mailman.zeta.org.au (8.9.3/8.8.7) with ESMTP id WAA16973;
	Mon, 9 Jul 2001 22:11:46 +1000
Date: Mon, 9 Jul 2001 22:09:41 +1000 (EST)
From: Bruce Evans <bde@zeta.org.au>
X-Sender: bde@besplex.bde.org
To: Dag-Erling Smorgrav <des@ofug.org>
Cc: arch@FreeBSD.ORG
Subject: Re: -fno-builtin
In-Reply-To: <xzpr8vqtjwh.fsf@flood.ping.uio.no>
Message-ID: <Pine.BSF.4.21.0107092158160.87629-100000@besplex.bde.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-freebsd-arch@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-arch.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo?subject=subscribe%20freebsd-arch>
List-Unsubscribe: <mailto:majordomo?subject=unsubscribe%20freebsd-arch>
X-Loop: FreeBSD.ORG

On 9 Jul 2001, Dag-Erling Smorgrav wrote:

> Bruce Evans <bde@zeta.org.au> writes:
> > Unfortunately, the inline function version doesn't work right, at least
> > on i386's:  __builtin_strlen("foo") gives code that loads the constant
> > result 3, but the inline strlen("foo") gives code that scans the string.
> 
> What about a macro?
> 
> #define strlen(s) __builtin_strlen(s)
> 
> Would this work?

I think it would work right except in broken code which "knows" that
strlen isn't a macro, e.g.:

	size_t (*p)(const char *s) = strlen;

and in non-broken code that avoids the macro, e.g.:

	size_t foo = (strlen)("123");

It only loses the optimization (if any) of using the builtin for non-broken
code.

This is only practical because there aren't many builtins for standard
functions.

Bruce


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-arch" in the body of the message