From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 77828 invoked by alias); 9 Feb 2017 15:50:08 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 77233 invoked by uid 89); 9 Feb 2017 15:50:08 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=1.0 required=5.0 tests=AWL,BAYES_50,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,RCVD_IN_SORBS_SPAM,SPF_PASS autolearn=no version=3.3.2 spammy=sk:mishra, mishra.nitish.88@gmail.com, mishranitish88gmailcom, sk:mishra. X-HELO: mail-qt0-f194.google.com Received: from mail-qt0-f194.google.com (HELO mail-qt0-f194.google.com) (209.85.216.194) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 09 Feb 2017 15:50:06 +0000 Received: by mail-qt0-f194.google.com with SMTP id w20so1027095qtb.1 for ; Thu, 09 Feb 2017 07:50:06 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=WqBxsh7rVYYToEuzWP9gOiCYaPE0CfD9qx85f2713H4=; b=LGf1XTJKKh8Wa1xXrsIu6NcpA68NBMIAq+2Oc5I94KIL/TulQIIB46iQOWrIp/yCPe M3iu8cDerZhNYKn+Y5x8tc1RBv1tv9VO+xKf+zPz8JZoHbAl37IMiHiRA7kQJr9crGGS cc/dcrnQv68eNLAIPvPzI2udtySRcCuGiEeXcYKGTGeGER+igWS53QJVx2PrCFBKh0HI cp57l9RQDb2NPwixRffYiMYAqiJs6pOHlChY4R6HbzJfRASfVqiskoZQ87mqMbfH2QxG 2P8BKgcVfdw8G8d72ZmMVTsnWQXcbS9eX3S/dHDMPMPSzKiAoiYFSMKbb2CEBGrwjvnA lruQ== X-Gm-Message-State: AMke39nEFnhlip0vwQqt7UV8Ld9smS+GhJ4QMiIgUwNXyFWPMq6xGFwfRvjbnhVJTG7pdOnmcLcbtEYILgSNSw== X-Received: by 10.200.52.27 with SMTP id u27mr3749153qtb.26.1486655404641; Thu, 09 Feb 2017 07:50:04 -0800 (PST) MIME-Version: 1.0 Received: by 10.12.181.202 with HTTP; Thu, 9 Feb 2017 07:50:04 -0800 (PST) In-Reply-To: References: <21a21388-b1d9-816c-377e-d4e084cc399e@redhat.com> <331a72d9-050c-7cd7-adc2-78e5f1ed6f85@redhat.com> <57147db4-83c3-2a8f-0c74-0efc6a94e9f5@redhat.com> From: David Edelsohn Date: Thu, 09 Feb 2017 15:50:00 -0000 Message-ID: Subject: Re: Issue with Latest GDB on AIX with GCC-6.12 To: Nitish Kumar Mishra Cc: Pedro Alves , "gdb@sourceware.org" , Yao Qi Content-Type: text/plain; charset=UTF-8 X-SW-Source: 2017-02/txt/msg00021.txt.bz2 On Thu, Feb 9, 2017 at 7:15 AM, Nitish Kumar Mishra wrote: > Hi all, > While sending the previous mail the statements got broken. > I am not sure if it is understandable. So, trying again :) > > 1. GDB with GCC-4.8.5, 32 bit mode, with or without static > options : NOT WORKING. > 2. GDB with GCC-4.8.5, 64 bit mode, with or without static > options : WORKING FINE Okay. This is why I was confused about GCC 4.8.5. I don't have any immediate intuition why 64 bit mode would have an effect on GCC. To me this implies a subtle AIX linker issue. I have experienced AIX ld behaving differently in 32 bit mode and 64 bit mode. > 3. GDB with GCC-6.1, 64 bit mode, with static options : NOT WORKING > 4. GDB with GCC-6.1, 64 bit mode, without static options : COMPILATION ERROR. > > P.S.: Static options means: -static-libstdc++ -static-libgcc What is the compilation error? Does GCC 4.8.5 and GCC 6.1 fail in the same manner? Neither catch the exception? GCC EH on AIX was improved (for GCC 6) to place EH tables in the read-only section so that they could be shared and not bloat the data section. This also changed the data encoding. But this change should not have affected the algorithm to find an exception handler. If it fails for both GCC 4.8 and GCC 6.1, that implies the problem is not a recent GCC change. It's possible that there is something wrong with the GCC code and it accidentally works sometime, or it's possible that there is some bad interaction between GCC and the AIX linker (like relocations or ordering of symbols). Because of the limited GDB functionality on AIX, debugging is difficult. We need some more information about exactly why the EH walker is failing to find the relevant EH frame. What is wrong with the table in the executable or in memory? Thanks, David