From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 24691 invoked by alias); 1 Feb 2012 13:32:33 -0000 Mailing-List: contact archer-help@sourceware.org; run by ezmlm Sender: Precedence: bulk List-Post: List-Help: List-Subscribe: List-Id: Received: (qmail 24681 invoked by uid 22791); 1 Feb 2012 13:32:32 -0000 X-SWARE-Spam-Status: No, hits=-6.7 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Date: Wed, 01 Feb 2012 13:32:00 -0000 From: Jakub Jelinek To: Jan Kratochvil Cc: archer@sourceware.org, Jason Merrill Subject: Re: Inter-CU DWARF size optimizations and gcc -flto Message-ID: <20120201133215.GQ18768@tyan-ft48-01.lab.bos.redhat.com> Reply-To: Jakub Jelinek References: <20120201132307.GA32578@host2.jankratochvil.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120201132307.GA32578@host2.jankratochvil.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-SW-Source: 2012-q1/txt/msg00006.txt.bz2 On Wed, Feb 01, 2012 at 02:23:09PM +0100, Jan Kratochvil wrote: > I am sorry if it is clear to everyone but I admit I played with it only > yesterday. > > With > gcc -flto -flto-partition=none > > gcc outputs only single CU (Compilation Unit). With default (omitting) > -flto-partition there are multiple CUs but still a few compared to the number > of .o files. > > -flto is AFAIK the future for all the compilations. It is well known -flto > debug info is somehow broken now but that needs to be fixed anyway. It isn't only somehow broken, it is quite fundamentally broken. And even with LTO GCC should output CUs matching the original source, one CU per source IMHO, which is admittedly going to be very difficult though, especially when partitioning the compilation, because multiple partitions might need to add stuff to a single CU. IMHO at least for us -flto is a no-go until these problems are solved though. Jakub