From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10555 invoked by alias); 31 Jan 2012 18:05:46 -0000 Received: (qmail 10535 invoked by uid 22791); 31 Jan 2012 18:05:45 -0000 X-SWARE-Spam-Status: No, hits=-2.8 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO sourceware.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 31 Jan 2012 18:05:33 +0000 From: "eager at eagercon dot com" To: gdb-prs@sourceware.org Subject: [Bug symtab/11717] common/.bss variables from shared libraries not displayed correctly Date: Tue, 31 Jan 2012 18:05:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gdb X-Bugzilla-Component: symtab X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: eager at eagercon dot com X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: 7.1 X-Bugzilla-Changed-Fields: CC Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Mailing-List: contact gdb-prs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-prs-owner@sourceware.org X-SW-Source: 2012-q1/txt/msg00140.txt.bz2 http://sourceware.org/bugzilla/show_bug.cgi?id=11717 eager at eagercon dot com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |eager at eagercon dot com --- Comment #3 from eager at eagercon dot com 2012-01-31 18:04:56 UTC --- As the test case shows, this problem is not limited to unintialized variables in .bss -- it also occurs with initialized variables in .data. The basic problem is that the DW_AT_location for the variable in the shared library is incorrect, since it does not match how the variable is accessed. It says that var is addressed directly, while in fact it is accessed indirectly through the GOT. GCC generates DW_OP_addr var which points to the unused copy of var in the shared library. The correct DWARF should be DW_OP_addr var@GOT DW_OP_deref I'm unclear what the patch is doing exactly, but to the extent it is having gdb ignore the generated debug info, as suggested by this comment + /* Never use DW_AT_location, rely on the minimal symbols. */ then this seems to be headed in the wrong direction. The best fix for incorrect debug data is to generate the correct info. Or this fix should be clearly identified as a workaround for incorrect data, with some way of defeating the workaround when correct data is present. Unfortunately, gdb does not currently support "complex" DWARF expressions which include an indirect reference. -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.