From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 25681 invoked by alias); 22 Jul 2002 14:10:36 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 25672 invoked from network); 22 Jul 2002 14:10:35 -0000 Received: from unknown (HELO uha.cs.bris.ac.uk) (65.123.213.2) by sources.redhat.com with SMTP; 22 Jul 2002 14:10:35 -0000 Received: from codesourcery.com (localhost.localdomain [127.0.0.1]) by uha.cs.bris.ac.uk (8.11.6/8.11.6) with ESMTP id g6ME9sT02143; Mon, 22 Jul 2002 15:09:54 +0100 Message-ID: <3D3C1231.2F39DDC@codesourcery.com> Date: Mon, 22 Jul 2002 12:33:00 -0000 From: Nathan Sidwell Organization: Codesourcery LLC X-Accept-Language: en MIME-Version: 1.0 To: Mark Mitchell CC: Gabriel Dos Reis , Jason Merrill , Richard Henderson , "gcc@gcc.gnu.org" Subject: Re: [tree-ssa] Simplifying TARGET_EXPR References: <52110000.1027288471@warlock.codesourcery.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-SW-Source: 2002-07/txt/msg01026.txt.bz2 Mark Mitchell wrote: > Maybe I'm developing an unhealthy paranoia. On the one hand, > optimizing away more copy constructors is like optimizinga away > more copies between scalars, and I'm all for having -O2 do more > of that! On the other, copy constructor elision is observable > behavior in the program, and it's going to make it hard to do > debug, profile, and otherwise analyze your program if the number > of copy constructor calls changes when you optimize. I disagree. Alias analysis makes optimized broken programs hard to debug, I don't see why temporary elision is any different.. Maybe have the elision separately disablable at -O2, but I think it should be permissable. nathan -- Dr Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery LLC 'But that's a lie.' - 'Yes it is. What's your point?' nathan@codesourcery.com : http://www.cs.bris.ac.uk/~nathan/ : nathan@acm.org