From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 27134 invoked by alias); 8 Jan 2010 01:01:35 -0000 Received: (qmail 24250 invoked by uid 48); 8 Jan 2010 01:01:04 -0000 Date: Fri, 08 Jan 2010 01:01:00 -0000 Message-ID: <20100108010104.24230.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug rtl-optimization/42631] [4.5 Regression] "-fcompare-debug failure" with "-O1 -funroll-loops" In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "aoliva at gcc dot gnu dot org" Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2010-01/txt/msg00876.txt.bz2 ------- Comment #7 from aoliva at gcc dot gnu dot org 2010-01-08 01:01 ------- The interesting question to ask is *why* web regards three different uses of the same uninitialized pseudo as different webs. That's what doesn't make sense to me. Apparently DF avoids dealing with uninitialized variables while constructing UD chains. If this was improved (say, creating an artificial def for the uninitialized pseudo), this symptom (the -fcompare-debug failure) would be automatically fixed. However, I can come up with a kludge for web, such as special-casing uninitialized uses in debug insns or so. Thoughts? -- aoliva at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |steven at gcc dot gnu dot | |org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42631