From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15340 invoked by alias); 21 Dec 2002 05:56:01 -0000 Mailing-List: contact gcc-prs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-prs-owner@gcc.gnu.org Received: (qmail 15326 invoked by uid 71); 21 Dec 2002 05:56:01 -0000 Date: Fri, 20 Dec 2002 21:56:00 -0000 Message-ID: <20021221055601.15325.qmail@sources.redhat.com> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org, From: Patrick Smith Subject: Re: optimization/9015: bc segfaults when compiled with optimization Reply-To: Patrick Smith X-SW-Source: 2002-12/txt/msg01163.txt.bz2 List-Id: The following reply was made to PR optimization/9015; it has been noted by GNATS. From: Patrick Smith To: bangerth@dealii.org, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org, nobody@gcc.gnu.org, patsmith@pobox.com, gcc-gnats@gcc.gnu.org Cc: Subject: Re: optimization/9015: bc segfaults when compiled with optimization Date: Sat, 21 Dec 2002 00:51:59 -0500 bangerth@dealii.org wrote: > Synopsis: bc segfaults when compiled with optimization > > State-Changed-From-To: open->feedback > State-Changed-By: bangerth > State-Changed-When: Fri Dec 20 19:20:49 2002 > State-Changed-Why: > It is very hard for us to reproduce a problem with such little > information, since we don't really know what we're looking > for. Sometimes such problems go away by moving to a different > platform, and then we would not be able to reproduce it. > Basically, a whole program is too large for us to find a > bug in. > > What you could do is the following: try to run bc under > a debugger and try to find out which function it crashes in > by looking at a stacktrace after the crash happens. Then > try to isolate the function in which this happens from > the rest of the program and see whether you can come up > with a small testcase from which we can work on. This > would ideally just include the one function in which things > happen, called from a dummy main function. > > Thanks > Wolfgang > > http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9015 As mentioned in the original report, I think the problem is with the function load_code in the source file included in the bug report. If that function is compiled without optimization and the rest of bc is optimized with -O2, the crash does not occur. I've already been the debugger and trying to create a small test program route, without much luck. The crash occurs in another function (addbyte in the same source file). I'm currently reading up on PowerPC assembly, so I can look at the generated code for load_code and figure out if it's right or not. If you want, I can send the .s file as well. -- patsmith@pobox.com