From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5000 invoked by alias); 26 Apr 2010 13:23:25 -0000 Received: (qmail 4986 invoked by uid 22791); 26 Apr 2010 13:23:22 -0000 X-SWARE-Spam-Status: No, hits=-1.9 required=5.0 tests=BAYES_00,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from gw1.transmode.se (HELO gw1.transmode.se) (213.115.205.20) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 26 Apr 2010 13:23:17 +0000 Received: from sesr04.transmode.se (sesr04.transmode.se [192.168.201.15]) by gw1.transmode.se (Postfix) with ESMTP id BC6E4650002; Mon, 26 Apr 2010 15:23:14 +0200 (CEST) In-Reply-To: References: Subject: Re: PowerPC suboptimal "add with carry" optimization X-KeepSent: 259FC7A4:449A416E-C1257711:00490316; type=4; name=$KeepSent To: David Edelsohn Cc: gcc@gcc.gnu.org, Ian Lance Taylor , =?ISO-8859-15?Q?Manuel_L=F3pez-Ib=E1=F1ez?= Message-ID: From: Joakim Tjernlund Date: Mon, 26 Apr 2010 13:27:00 -0000 MIME-Version: 1.0 Content-type: text/plain; charset=ISO-8859-15 Content-transfer-encoding: quoted-printable Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org X-SW-Source: 2010-04/txt/msg00812.txt.bz2 David Edelsohn wrote on 2010/04/26 14:54:55: > > On Mon, Apr 26, 2010 at 8:21 AM, Joakim Tjernlund > wrote: > > Manuel L=F3pez-Ib=E1=F1ez wrote on 2010/04/26 1= 3:59:04: > >> On 26 April 2010 09:13, Joakim Tjernlund wrote: > >> > Ian Lance Taylor wrote on 2010/04/25 20:07:03: > >> >> Joakim Tjernlund writes: > >> >> > >> >> > Noticed that gcc 4.3.4 doesn't optimize "add with carry" properly: > >> >> > >> >> Please file a missed-optimization report according to > >> >> http://gcc.gnu.org/bugs/ . =A0Thanks. > >> > > >> > I rather not, going through all that just for one odd report. I was = hoping > >> > an interested part would pick it up from my email. > >> > >> What is to be done besides what you have done here but in a more > >> useful, structured manner? I am asking because we want to make things > >> simple but not simpler than they become more complex for us. > > > > Lots of stuff to read on that page, lots of info to supply, > > registering an account, specify all that system info and so on. > > You do not need to register an account to report a bug or request a Just tried that and don't see that. > feature enhancement. Some of the information can be left blank, but > if we do not have information about the system and an example, we may > not understand the request or may not be able to reproduce the problem > and fix it. Just go look at that page, it is so much info that if the bug isn't very im= portat you quickly decide it is not worth it. How I am supposed to know what is ne= ed or not without reading all that? > > >> Aren't you interested in someone fixing the bug? > > > > Sure or better yet, show me some way to restructure the C code so proper > > asm code is generated. > > You referred to PowerPC patterns in GCC that use the carry > instructions. Those patterns are optimizations for materializing a > truthvalue in a GPR or performance a 64 bit arithmetic operation in 32 > bit mode. The PowerPC port of GCC does not recognize general carry > arithmetic operations yet and track the carry bit. OK, thanks. I know x86 do I had hope there was some way to do that i PowerPC too.