From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-return-105988-listarch-gcc=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 30531 invoked by alias); 30 Nov 2004 00:22:38 -0000
Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Archive: <http://gcc.gnu.org/ml/gcc/>
List-Post: <mailto:gcc@gcc.gnu.org>
List-Help: <http://gcc.gnu.org/ml/>
Sender: gcc-owner@gcc.gnu.org
Received: (qmail 30520 invoked from network); 30 Nov 2004 00:22:34 -0000
Received: from unknown (HELO Cantor.suse.de) (195.135.220.2)
  by sourceware.org with SMTP; 30 Nov 2004 00:22:34 -0000
Received: from hermes.suse.de (hermes-ext.suse.de [195.135.221.8])
	(using TLSv1 with cipher EDH-RSA-DES-CBC3-SHA (168/168 bits))
	(No client certificate requested)
	by Cantor.suse.de (Postfix) with ESMTP id D543A11860FC;
	Tue, 30 Nov 2004 01:22:33 +0100 (CET)
To: Paul Schlie <schlie@comcast.net>
Cc: <gcc@gcc.gnu.org>
Subject: Re: warning: right shift count >= width of type
References: <BDD11A9E.815E%schlie@comcast.net>
From: Andreas Schwab <schwab@suse.de>
X-Yow: ..  If I had heart failure right now, I couldn't be a more fortunate
 man!!
Date: Tue, 30 Nov 2004 01:50:00 -0000
In-Reply-To: <BDD11A9E.815E%schlie@comcast.net> (Paul Schlie's message of
 "Mon, 29 Nov 2004 18:27:42 -0500")
Message-ID: <jeoehg4246.fsf@sykes.suse.de>
User-Agent: Gnus/5.110002 (No Gnus v0.2) Emacs/21.3.50 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: 8bit
X-SW-Source: 2004-11/txt/msg01181.txt.bz2

Paul Schlie <schlie@comcast.net> writes:

> It likely needs to define what (x << z) means if:
>
> - z lesser-or-equal-to 0, [i.e. does (x << -1) == (x >> 1) ?]

Since left and right shift are usually separate insns this would result in
a runtime penalty.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."