Re: c++/8684: ABI Issue: gcc3.2 is not reusing tail-padding..

Re: c++/8684: ABI Issue: gcc3.2 is not reusing tail-padding..

[bangerth]

Synopsis: ABI Issue:   gcc3.2 is not reusing tail-padding..

Responsible-Changed-From-To: unassigned->mmitchel
Responsible-Changed-By: bangerth
Responsible-Changed-When: Tue Dec  3 12:44:29 2002
Responsible-Changed-Why:
    The person who probably knows the most about this part
    of the standard
State-Changed-From-To: feedback->analyzed
State-Changed-By: bangerth
State-Changed-When: Tue Dec  3 12:44:29 2002
State-Changed-Why:
    Yes, this is wicked. gcc 2.95, 3.2, 3.2.2 and 3.3 do indeed not reuse
    the tail padding in this example; it does also not matter
    whether I specifiy -fabi-version=0 or 1 or 2. Also, icc6.0
    does not. But gcc3.0.4 and icc7 do! I don't know what the standard
    says, but it seems like worth someone knowledgable check
    this.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8684

Re: c++/8684: ABI Issue: gcc3.2 is not reusing tail-padding..

[nathan]

Synopsis: ABI Issue:   gcc3.2 is not reusing tail-padding..

Responsible-Changed-From-To: mmitchel->nathan
Responsible-Changed-By: nathan
Responsible-Changed-When: Fri Jan 24 17:17:17 2003
Responsible-Changed-Why:
    analyzer
State-Changed-From-To: analyzed->closed
State-Changed-By: nathan
State-Changed-When: Fri Jan 24 17:17:17 2003
State-Changed-Why:
    yup, not a bug. C1 is POD

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8684

Re: c++/8684: ABI Issue: gcc3.2 is not reusing tail-padding..

[Giovanni Bajo]

The following reply was made to PR c++/8684; it has been noted by GNATS.

From: "Giovanni Bajo" <giovannibajo@libero.it>
To: <gcc-gnats@gcc.gnu.org>,
	<sunil.k.davasam@intel.com>,
	<gcc-bugs@gcc.gnu.org>,
	<mmitchel@gcc.gnu.org>,
	<gcc-prs@gcc.gnu.org>
Cc:  
Subject: Re: c++/8684: ABI Issue:   gcc3.2 is not reusing tail-padding..
Date: Fri, 24 Jan 2003 17:54:49 +0100

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&p
 r=8684
 
 GCC is correct here because C1 is of POD type, and tail padding can be
 reused only in non-POD types. Comeau agrees, I don't know why ICC does not.
 Besides, Mark already commented this very code snippet:
 
 http://gcc.gnu.org/ml/gcc/2002-11/msg00474.html
 
 IMO, this is not a bug and should be closed.
 
 Giovanni Bajo
 

RE: c++/8684: ABI Issue: gcc3.2 is not reusing tail-padding..

[Wolfgang Bangerth]

The following reply was made to PR c++/8684; it has been noted by GNATS.

From: Wolfgang Bangerth <bangerth@ticam.utexas.edu>
To: gcc-gnats@gcc.gnu.org
Cc:  
Subject: RE: c++/8684: ABI Issue:   gcc3.2 is not reusing tail-padding..
Date: Tue, 3 Dec 2002 14:35:00 -0600 (CST)

 ---------- Forwarded message ----------
 Date: Tue, 3 Dec 2002 12:08:57 -0800
 From: "Davasam, Sunil K" <sunil.k.davasam@intel.com>
 To: bangerth@dealii.org
 Subject: RE: c++/8684: ABI Issue:   gcc3.2 is not reusing tail-padding..
 
 Sorry for the late reply. I tried with intel 6.0,7.0 compilers on Linux.
 In both cases I am getting same result. Here are the details.
 
 [skdavasa@crystal tmp]$ cat t4.cpp 
 #include <stdio.h>
 
 struct C1 {
        int i;
        char c;
 };
 
 struct C2 : C1 {
        char c;
 };
 
 int main()
 {
         printf("sizeof (C1) = %d\n", sizeof (C1) );
         printf("sizeof (C2) = %d\n", sizeof (C2) );
         return 0;
 }
 
 [skdavasa@crystal tmp]$ icpc t4.cpp 
 t4.cpp
 [skdavasa@crystal tmp]$ a.out
 sizeof (C1) = 8
 sizeof (C2) = 8
 [skdavasa@crystal ~/tmp]$ icpc -V
 Intel(R) C++ Compiler for 32-bit applications, Version 6.0.1   Build 20021018Z
 Copyright (C) 1985-2002 Intel Corporation.  All rights reserved.
 
 [skdavasa@crystal ~/tmp]$ source ~/.ia32_productrc 70
 [skdavasa@crystal ~/tmp]$ icpc -V
 Intel(R) C++ Compiler for 32-bit applications, Version 7.0   Build 20021021Z
 Copyright (C) 1985-2002 Intel Corporation.  All rights reserved.
 
 [skdavasa@crystal ~/tmp]$ icpc t4.cpp 
 [skdavasa@crystal ~/tmp]$ a.out
 sizeof (C1) = 8
 sizeof (C2) = 8
 ---
       
 Thanks & Regards,
 -Sunil.
 
 
 -----Original Message-----
 From: bangerth@dealii.org [mailto:bangerth@dealii.org]
 Sent: Tuesday, November 26, 2002 7:30 PM
 To: gcc-bugs@gcc.gnu.org; gcc-prs@gcc.gnu.org; nobody@gcc.gnu.org;
 Davasam, Sunil K
 Subject: Re: c++/8684: ABI Issue: gcc3.2 is not reusing tail-padding..
 
 
 Synopsis: ABI Issue:   gcc3.2 is not reusing tail-padding..
 
 State-Changed-From-To: open->feedback
 State-Changed-By: bangerth
 State-Changed-When: Tue Nov 26 19:29:32 2002
 State-Changed-Why:
     Between 3.1.1 and 3.2, a number of ABI bugs have been fixed.
     This may be one of them. The question I have for you, is
     which version of the Intel compiler you have been using?
     If I use icc 6.0 on Linux, I get 8 and 12, so exactly
     the same results as with gcc3.2. So to me it seems as if
     they were now compatible in this respect.
     
     Thanks
       Wolfgang
 
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8684