From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14597 invoked by alias); 24 Aug 2010 19:55:27 -0000 Received: (qmail 14586 invoked by uid 22791); 24 Aug 2010 19:55:26 -0000 X-SWARE-Spam-Status: No, hits=-4.4 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,TW_TM,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, 24 Aug 2010 19:55:22 +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 (8.13.8/8.13.8) with ESMTP id o7OJtLSG031267 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 24 Aug 2010 15:55:21 -0400 Received: from patootie.office.frob.com (ovpn-113-34.phx2.redhat.com [10.3.113.34]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o7OJtLFf004249; Tue, 24 Aug 2010 15:55:21 -0400 Received: from magilla.sf.frob.com (magilla.office.frob.com [198.49.250.228]) by patootie.office.frob.com (Postfix) with ESMTP id 8FA014019; Tue, 24 Aug 2010 12:55:20 -0700 (PDT) Received: by magilla.sf.frob.com (Postfix, from userid 5281) id 9C0D74048C; Tue, 24 Aug 2010 12:55:19 -0700 (PDT) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit From: Roland McGrath To: Josh Stone Cc: systemtap@sources.redhat.com Subject: Re: semantic error: multiple addresses for ... In-Reply-To: Josh Stone's message of Tuesday, 24 August 2010 12:48:16 -0700 <4C742200.7000401@redhat.com> References: <20100820203946.0169540144@magilla.sf.frob.com> <4C742200.7000401@redhat.com> Message-Id: <20100824195519.9C0D74048C@magilla.sf.frob.com> Date: Tue, 24 Aug 2010 19:55:00 -0000 X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2010-q3/txt/msg00289.txt.bz2 > For more history, see commit 897820ca and PR1306. > > http://sourceware.org/git/gitweb.cgi?p=systemtap.git;h=897820ca > http://sourceware.org/bugzilla/show_bug.cgi?id=1306 Thanks for these pointers. > In comment #2, some guy named Roland indicates that this may be a > non-trivial problem in the general case... Indeed it is. The question is how best to resolve it. IMHO the current situation is not good. Off hand, I see two potential approaches: 1. Pay attention to is_stmt. I mentioned this earlier. To consider this, we'd really need to find some cases where the current code legitimately complains as in PR1306, and check whether the is_stmt flags in that DWARF info are useful. 2. Apply the current rule only when there are multiple hits in the same scope. This seems probably safer than relying on is_stmt, though it's not clear. This should fix the case I just reported, and ones like it, where the multiple hits are in entirely different instances of the same source code. This too could possibly go wrong due to unusual optimization choices, but it seems far less likely. Thanks, Roland