From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15388 invoked by alias); 25 Jan 2008 12:26:19 -0000 Received: (qmail 15380 invoked by uid 22791); 25 Jan 2008 12:26:18 -0000 X-Spam-Check-By: sourceware.org Received: from exprod6og104.obsmtp.com (HELO exprod6og104.obsmtp.com) (64.18.1.187) by sourceware.org (qpsmtpd/0.31) with ESMTP; Fri, 25 Jan 2008 12:25:59 +0000 Received: from source ([192.150.20.142]) by exprod6ob104.postini.com ([64.18.5.12]) with SMTP; Fri, 25 Jan 2008 04:25:55 PST Received: from inner-relay-3.eur.adobe.com (inner-relay-3b [10.128.4.236]) by outbound-smtp-2.corp.adobe.com (8.12.10/8.12.10) with ESMTP id m0PCPmGb027066; Fri, 25 Jan 2008 04:25:48 -0800 (PST) Received: from fe1.corp.adobe.com (fe1.corp.adobe.com [10.8.192.70]) by inner-relay-3.eur.adobe.com (8.12.10/8.12.9) with ESMTP id m0PCPlFV021478; Fri, 25 Jan 2008 04:25:47 -0800 (PST) Received: from namailgen.corp.adobe.com ([10.8.192.91]) by fe1.corp.adobe.com with Microsoft SMTPSVC(6.0.3790.1830); Fri, 25 Jan 2008 04:25:46 -0800 Received: from 10.32.16.88 ([10.32.16.88]) by namailgen.corp.adobe.com ([10.8.192.91]) via Exchange Front-End Server namailhost.corp.adobe.com ([10.8.192.70]) with Microsoft Exchange Server HTTP-DAV ; Fri, 25 Jan 2008 12:25:46 +0000 User-Agent: Microsoft-Entourage/11.3.6.070618 Date: Sat, 26 Jan 2008 02:33:00 -0000 Subject: Re: Why does gcc produce an unnecessary `nop' instruction? From: John Love-Jensen To: PRC CC: MSX to GCC Message-ID: In-Reply-To: <200801251719424202892@gmail.com> Mime-version: 1.0 Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit X-IsSubscribed: yes Mailing-List: contact gcc-help-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-help-owner@gcc.gnu.org X-SW-Source: 2008-01/txt/msg00254.txt.bz2 Hi PRC, > Is there a particular good reason for 8-byte alignment, even if the target ARCH is 32-bit rather than 64-bit and aligment is quite a little waste of storage and runtime memory? Perhaps your platform supports 64-bit floating point, and that entails alignment requirements? Sometimes the "requirements" are performance related (e.g. Intel), sometimes they avoid SIGBUS but can be "faked" with a sigtrap to handle misalignment (such as what could be done on the DEC Alpha), sometimes they are really hard requirements such as MMX/SSE or AltiVec. Hard to say without looking at the config file for your particular platform. Sincerely, --Eljay