From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 13654 invoked by alias); 22 Jul 2002 09:24:52 -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 13630 invoked from network); 22 Jul 2002 09:24:49 -0000 Received: from unknown (HELO Cantor.suse.de) (213.95.15.193) by sources.redhat.com with SMTP; 22 Jul 2002 09:24:49 -0000 Received: from Hermes.suse.de (Charybdis.suse.de [213.95.15.201]) by Cantor.suse.de (Postfix) with ESMTP id 6B3761452B; Mon, 22 Jul 2002 11:24:48 +0200 (MEST) Date: Mon, 22 Jul 2002 08:32:00 -0000 From: Michael Matz To: Mark Mitchell , Gabriel Dos Reis Cc: "gcc@gcc.gnu.org" Subject: Re: [tree-ssa] Simplifying TARGET_EXPR In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SW-Source: 2002-07/txt/msg01016.txt.bz2 Hi, On Sun, 21 Jul 2002, Mark Mitchell wrote: > > Do you think we should always elide copy-constructors by default, > > unless explicitly told the contrary? > > Yes. > > Maybe I'm developing an unhealthy paranoia. And your coworkers too it seems ;-) First, I think you meant debugging in general, not specifically with gdb, didn't you? Because with -O2 programs are not debuggable easily with gdb, even right now, so gdb-debugging should not be the reason to not elide copy ctors (or more generally debugging with programs interpreting the debug info). Then it can only be a form of printf debugging, or asserts. But e.g. strict aliasing makes such debugging also harder in a similar way, because valid, but possibly surprising, transformations are made. We do them anyway, so that also can't be the reason to not elide copy ctors by default. So not eliding them should be done only when a switch is given. Maybe -fno-surprising (which also would switch off other optimizations), or -fdebug. Ciao, Michael.