From owner-svn-src-stable@FreeBSD.ORG  Tue Dec 11 12:58:28 2012
Return-Path: <owner-svn-src-stable@FreeBSD.ORG>
Delivered-To: svn-src-stable@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
 by hub.freebsd.org (Postfix) with ESMTP id 8AC2DC27;
 Tue, 11 Dec 2012 12:58:28 +0000 (UTC)
 (envelope-from emaste@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org
 [IPv6:2001:1900:2254:2068::e6a:0])
 by mx1.freebsd.org (Postfix) with ESMTP id 54A628FC13;
 Tue, 11 Dec 2012 12:58:28 +0000 (UTC)
Received: from svn.freebsd.org (localhost [127.0.0.1])
 by svn.freebsd.org (8.14.5/8.14.5) with ESMTP id qBBCwS2v096139;
 Tue, 11 Dec 2012 12:58:28 GMT (envelope-from emaste@svn.freebsd.org)
Received: (from emaste@localhost)
 by svn.freebsd.org (8.14.5/8.14.5/Submit) id qBBCwSg3096138;
 Tue, 11 Dec 2012 12:58:28 GMT (envelope-from emaste@svn.freebsd.org)
Message-Id: <201212111258.qBBCwSg3096138@svn.freebsd.org>
From: Ed Maste <emaste@FreeBSD.org>
Date: Tue, 11 Dec 2012 12:58:28 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org
Subject: svn commit: r244119 - stable/8/contrib/gdb/gdb
X-SVN-Group: stable-8
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-BeenThere: svn-src-stable@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: SVN commit messages for all the -stable branches of the src tree
 <svn-src-stable.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/svn-src-stable>,
 <mailto:svn-src-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-stable>
List-Post: <mailto:svn-src-stable@freebsd.org>
List-Help: <mailto:svn-src-stable-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-stable>,
 <mailto:svn-src-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 11 Dec 2012 12:58:28 -0000

Author: emaste
Date: Tue Dec 11 12:58:27 2012
New Revision: 244119
URL: http://svnweb.freebsd.org/changeset/base/244119

Log:
  MFC r242943: Do not unwind past a zero PC frame.
  
    This improves GDB usability when debugging code compiled with
    optimization.
  
    Upstream GDB revision f0031b6d3ae9b164b3747986ab898190bd4dcf8c (prior
    to GDB's switch to GPLv3), with frame_debug_got_null_frame expanded
    inline.
  
    | 2004-12-12  Andrew Cagney  <cagney@gnu.org>
    |
    | * frame.c (get_prev_frame): When unwinding normal frames, check
    | that the PC isn't zero.
  
  Sponsored by:	ADARA Networks

Modified:
  stable/8/contrib/gdb/gdb/frame.c
Directory Properties:
  stable/8/contrib/gdb/   (props changed)

Modified: stable/8/contrib/gdb/gdb/frame.c
==============================================================================
--- stable/8/contrib/gdb/gdb/frame.c	Tue Dec 11 12:57:08 2012	(r244118)
+++ stable/8/contrib/gdb/gdb/frame.c	Tue Dec 11 12:58:27 2012	(r244119)
@@ -1846,6 +1846,23 @@ get_prev_frame (struct frame_info *this_
       return NULL;
     }
 
+  /* Assume that the only way to get a zero PC is through something
+     like a SIGSEGV or a dummy frame, and hence that NORMAL frames
+     will never unwind a zero PC.  */
+  if (this_frame->level > 0
+      && get_frame_type (this_frame) == NORMAL_FRAME
+      && get_frame_type (get_next_frame (this_frame)) == NORMAL_FRAME
+      && get_frame_pc (this_frame) == 0)
+    {
+      if (frame_debug)
+	{
+	  fprintf_unfiltered (gdb_stdlog, "-> ");
+	  fprint_frame (gdb_stdlog, this_frame->prev);
+	  fprintf_unfiltered (gdb_stdlog, " // zero PC \n");
+	}
+      return NULL;
+    }
+
   /* Only try to do the unwind once.  */
   if (this_frame->prev_p)
     {