From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 21003 invoked by alias); 15 Feb 2011 19:07:40 -0000 Received: (qmail 20990 invoked by uid 22791); 15 Feb 2011 19:07:40 -0000 X-SWARE-Spam-Status: No, hits=-6.4 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 15 Feb 2011 19:07:36 +0000 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p1FJ7YQU021013 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 15 Feb 2011 14:07:34 -0500 Received: from tyan-ft48-01.lab.bos.redhat.com (tyan-ft48-01.lab.bos.redhat.com [10.16.42.4]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p1FJ7Xgk025169 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 15 Feb 2011 14:07:34 -0500 Received: from tyan-ft48-01.lab.bos.redhat.com (localhost.localdomain [127.0.0.1]) by tyan-ft48-01.lab.bos.redhat.com (8.14.4/8.14.4) with ESMTP id p1FJ7XlE021740; Tue, 15 Feb 2011 20:07:33 +0100 Received: (from jakub@localhost) by tyan-ft48-01.lab.bos.redhat.com (8.14.4/8.14.4/Submit) id p1FJ7XWl021739; Tue, 15 Feb 2011 20:07:33 +0100 Date: Tue, 15 Feb 2011 19:07:00 -0000 From: Jakub Jelinek To: Alexandre Oliva Cc: gcc-patches@gcc.gnu.org Subject: Re: [PR debug/47624] improve value tracking in non-VTA locations Message-ID: <20110215190732.GT30899@tyan-ft48-01.lab.bos.redhat.com> Reply-To: Jakub Jelinek References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-IsSubscribed: yes Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org X-SW-Source: 2011-02/txt/msg00996.txt.bz2 On Tue, Feb 15, 2011 at 04:14:29PM -0200, Alexandre Oliva wrote: > VTA only tracks locations of gimple regs, while addressable variables > still use the old var tracking strategy. This means addressable > variables, during var-tracking, got locations that were not based on > VALUEs, which failed immediately in the presence of auto-inc addresses. > The locations also tended to degrade in other ways, when a register > holding an address happened to be overwritten at a later point. > > This patch arranges for us to track addresses of these variables as > VALUEs, and to emit new locations for them when a location whose value > was used to compute its address changes, fixing the problem. > > The patch was regstrapped on x86_64-linux-gnu and i686-linux-gnu. Ok to > install? > While I think it is a good idea, I'd say this should be stage 1 material, after all it isn't a regression. For the testcase in question I think we also want to improve cselib.c as I wrote in the PR, to canonicalize locs of VALUE + CONST_INT M when VALUE has locs of the form VALUE' + CONST_INT N to VALUE' + CONST_INT (M + N), then we'd figure out we should use fbreg and don't need to change the location description through the function. > for gcc/ChangeLog > from Alexandre Oliva > > PR deug/47624 s/deug/debug/ > * var-tracking.c (add_stores): Add FIXME note. > (compute_bb_dataflow): Use value-based locations in MO_VAL_SET. > (emit_notes_in_bb): Likewise. > (check_changed_vars_4): New. > (emit_noets_for_changes): Call it. s/noets/notes/ Jakub