From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 31787 invoked by alias); 21 May 2010 16:13:29 -0000 Received: (qmail 31774 invoked by uid 22791); 21 May 2010 16:13:27 -0000 X-SWARE-Spam-Status: No, hits=-1.7 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from smtp-out.google.com (HELO smtp-out.google.com) (216.239.44.51) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 21 May 2010 16:13:15 +0000 Received: from wpaz29.hot.corp.google.com (wpaz29.hot.corp.google.com [172.24.198.93]) by smtp-out.google.com with ESMTP id o4LGDCjj014148 for ; Fri, 21 May 2010 09:13:12 -0700 Received: from vws12 (vws12.prod.google.com [10.241.21.140]) by wpaz29.hot.corp.google.com with ESMTP id o4LGCSKd008364 for ; Fri, 21 May 2010 09:13:11 -0700 Received: by vws12 with SMTP id 12so942362vws.31 for ; Fri, 21 May 2010 09:13:10 -0700 (PDT) MIME-Version: 1.0 Received: by 10.220.107.167 with SMTP id b39mr1232931vcp.16.1274458390820; Fri, 21 May 2010 09:13:10 -0700 (PDT) Received: by 10.220.43.131 with HTTP; Fri, 21 May 2010 09:13:10 -0700 (PDT) In-Reply-To: References: <4BF58AE0.3090103@redhat.com> Date: Fri, 21 May 2010 17:06:00 -0000 Message-ID: Subject: Re: Where does the time go? From: Xinliang David Li To: Richard Guenther Cc: Steven Bosscher , Ian Lance Taylor , Vladimir Makarov , GCC Mailing List Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-System-Of-Record: true X-IsSubscribed: yes 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: 2010-05/txt/msg00427.txt.bz2 On Fri, May 21, 2010 at 2:24 AM, Richard Guenther wrote: > On Thu, May 20, 2010 at 11:21 PM, Xinliang David Li = wrote: >> On Thu, May 20, 2010 at 2:18 PM, Steven Bosscher = wrote: >>> On Thu, May 20, 2010 at 11:14 PM, Xinliang David Li wrote: >>>> stack variable overlay and stack slot assignments is here too. >>> >>> Yes, and for these I would like to add a separate timevar. Agree? >> >> Yes. =A0(By the way, we are rewriting this pass to eliminate the code >> motion/aliasing problem -- but that is a different topic). > > Btw, we want to address the same problem by representing the > points where (big) variables go out-of scope in the IL, also to > help DSE. =A0The original idea was to simply drop in an aggregate > assignment from an undefined value at the end of the scope > during lowering, like > > =A0var =3D {undefined}; > > which we'd expand to nothing. =A0Of course shifting the problem to > the RTL optimizers, so better expand to a similar RTL construct. > But then are you addressing the similar problem on the RTL side? We are probably talking about different problems -- the one I mentioned is that code motion leading to overlapping live range for variables in different scopes which invalidates the scope based stack variable overlay. What is the problem you referred? Any PR? I wonder why a dummy assignment is needed. Thanks, David > > Richard. >