From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15359 invoked by alias); 26 Jan 2006 23:33:15 -0000 Received: (qmail 15351 invoked by uid 22791); 26 Jan 2006 23:33:15 -0000 X-Spam-Check-By: sourceware.org Received: from nevyn.them.org (HELO nevyn.them.org) (66.93.172.17) by sourceware.org (qpsmtpd/0.31.1) with ESMTP; Thu, 26 Jan 2006 23:33:14 +0000 Received: from drow by nevyn.them.org with local (Exim 4.54) id 1F2Gc3-0005aQ-79; Thu, 26 Jan 2006 18:33:11 -0500 Date: Fri, 27 Jan 2006 00:02:00 -0000 From: Daniel Jacobowitz To: Igor Khavkine Cc: gdb@sourceware.org Subject: Re: C99 variable length arrays Message-ID: <20060126233311.GA21429@nevyn.them.org> Mail-Followup-To: Igor Khavkine , gdb@sourceware.org References: <20060126134926.GA3501@nevyn.them.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.8i X-IsSubscribed: yes Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2006-01/txt/msg00289.txt.bz2 On Thu, Jan 26, 2006 at 06:30:56PM -0500, Igor Khavkine wrote: > On 1/26/06, Daniel Jacobowitz wrote: > > On Thu, Jan 26, 2006 at 08:41:46AM -0500, Igor Khavkine wrote: > > > > I'm using GDB to debug some code that uses local variable length > > > arrays. This feature is available for C as of the C99 standard. GCC > > > has support for it. > > > > > > Sadly, GDB doesn't seem to be smart enough to figure out the size of > > > the arrays at run time. This leads to things like 'print array[1][2]' > > > at the GDB prompt not printing the same value as would 'printf("%g\n", > > > array[1][2])' in the code. This is a problem for multidimensional > > > arrays especially. Needless to say, this makes the code more difficult > > > to debug. > > > > The first thing to do is to write a small testcase, and post the > > testcase along with the debugging output that your GCC generates > > for it. > > There is a test case already in the GDB bug database (PR 1796, as I > mentioned in my first message). What kind of debugging output should I > post? Is there an option to make gcc dump the debugging info in human > readable form? Not really - but you can run readelf -wi on the resulting object file. I recommend you do this after linking to make sure relocations are resolved. -- Daniel Jacobowitz CodeSourcery