From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-333550-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 29431 invoked by alias); 11 Oct 2010 22:00:26 -0000
Received: (qmail 29422 invoked by uid 22791); 11 Oct 2010 22:00:25 -0000
X-SWARE-Spam-Status: No, hits=-2.6 required=5.0	tests=ALL_TRUSTED,AWL,BAYES_00
X-Spam-Check-By: sourceware.org
Received: from localhost (HELO gcc.gnu.org) (127.0.0.1)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 11 Oct 2010 22:00:18 +0000
From: "tromey at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug debug/45973] New: NRVO gives incorrect location
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: debug
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: tromey at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields:
Message-ID: <bug-45973-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Date: Mon, 11 Oct 2010 22:00:00 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2010-10/txt/msg00939.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45973

           Summary: NRVO gives incorrect location
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: tromey@gcc.gnu.org


This test case comes from gdb bugzilla.

class foo
{
public:
    int bar;
    ~foo(){};
};

foo f()
{
    foo x;
    x.bar = 1;
    x.bar = x.bar;
    return x;
};

int main()
{
    f();
};


Compile with -g.  Then, look at 'x' in the DWARF.  I see:

 <3><cf>: Abbrev Number: 15 (DW_TAG_variable)
    <d0>   DW_AT_name        : x    
    <d2>   DW_AT_decl_file   : 1    
    <d3>   DW_AT_decl_line   : 10    
    <d4>   DW_AT_type        : <0x29>    
    <d8>   DW_AT_location    : 1 byte block: 52     (DW_OP_reg2)

I think this is missing a DW_OP_deref.
That is, I think reg2 points to the object, it doesn't hold the object.