Re: c++/8249: Objects moved from common to BSS with -fdata-sections

[Wolfgang Bangerth <bangerth@ticam.utexas.edu>]

The following reply was made to PR c++/8249; it has been noted by GNATS.

From: Wolfgang Bangerth <bangerth@ticam.utexas.edu>
To: rittle@labs.mot.com
Cc: gcc-gnats@gcc.gnu.org
Subject: Re: c++/8249: Objects moved from common to BSS with -fdata-sections
Date: Fri, 20 Dec 2002 11:15:12 -0600 (CST)

 [Let's keep cross-posting to the database, just in case someone else is 
 interested in these mails.]
 
 On Thu, 19 Dec 2002, Loren James Rittle wrote:
 
 > In article <20021220012230.3437.qmail@sources.redhat.com>,
 > <bangerth@dealii.org> writes:
 > 
 > >     Loren, can you tell whether this still happens? I can't
 > >     reproduce this, but admittedly I only have a Linux box,
 > >     so maybe this is really target specific.
 > 
 > Yes, with mainline built today, it still exists.  Thanks for checking
 > results in your environment.  If you don't mind, could you repeat the
 > following steps and e-mail the results to me.
 > 
 > $ g++ -S -o tX t2.ii
 > $ g++ -fdata-sections -S -o tY t2.ii 
 > $ diff tX tY
 > 19,20c19,32
 > <       .comm   _ZGVZN3fooILi0EE3barEvE10double_foo,8,8
 > <       .comm   _ZZN3fooILi0EE3barEvE10double_foo,4,4
 > ---
 > > .globl _ZGVZN3fooILi0EE3barEvE10double_foo
 > >       .section        .bss._ZGVZN3fooILi0EE3barEvE10double_foo,"aw",@nobits
 > >       .align 8
 > >       .type   _ZGVZN3fooILi0EE3barEvE10double_foo, @object
 > >       .size   _ZGVZN3fooILi0EE3barEvE10double_foo, 8
 > > _ZGVZN3fooILi0EE3barEvE10double_foo:
 > >       .zero   8
 > > .globl _ZZN3fooILi0EE3barEvE10double_foo
 > >       .section        .bss._ZZN3fooILi0EE3barEvE10double_foo,"aw",@nobits
 > >       .align 4
 > >       .type   _ZZN3fooILi0EE3barEvE10double_foo, @object
 > >       .size   _ZZN3fooILi0EE3barEvE10double_foo, 4
 > > _ZZN3fooILi0EE3barEvE10double_foo:
 > >       .zero   4
 > 
 > Knowing what Linux does might help me understand more about this
 > problem.  Linux does properly support -fdata-sections, no?  In my
 > case, the linker is GNU ld version 2.13 20020917 (and also tested with
 > GNU ld version 2.12.1 [FreeBSD] 2002-07-20).
 
 I have no idea how well Linux supports -fdata-sections. To be honest, I 
 don't even know properly what this is about, I was just going through bug 
 reports and checked whether they apply to my box as well and if I can 
 contribute something :-)
 
 This is my configuration:
 tmp/g> ld -V
 GNU ld version 2.11.92.0.10 20011021 (SuSE)
   Supported emulations:
    elf_i386
    i386linux
 tmp/g> cat /proc/version
   Linux version 2.4.18-4GB (root@Pentium.suse.de) (gcc version 2.95.3 
   20010315 (SuSE)) #1 Wed Mar 27 13:57:05 UTC 2002
 
 And here's what I get is this (with yesterday's mainline):
 
 tmp/g> /home/bangerth/bin/gcc-3.4-CVS/bin/c++ -S -o tX t2.ii
 tmp/g> /home/bangerth/bin/gcc-3.4-CVS/bin/c++ -fdata-sections -S -o tY 
 t2.ii
 tmp/g> diff tX tY
 19,20c19,32
 <       .comm   _ZGVZN3fooILi0EE3barEvE10double_foo,8,8
 <       .comm   _ZZN3fooILi0EE3barEvE10double_foo,4,4
 ---
 > .globl _ZGVZN3fooILi0EE3barEvE10double_foo
 >       .section        .bss._ZGVZN3fooILi0EE3barEvE10double_foo,"aw",@nobits
 >       .align 8
 >       .type   _ZGVZN3fooILi0EE3barEvE10double_foo, @object
 >       .size   _ZGVZN3fooILi0EE3barEvE10double_foo, 8
 > _ZGVZN3fooILi0EE3barEvE10double_foo:
 >       .zero   8
 > .globl _ZZN3fooILi0EE3barEvE10double_foo
 >       .section        .bss._ZZN3fooILi0EE3barEvE10double_foo,"aw",@nobits
 >       .align 4
 >       .type   _ZZN3fooILi0EE3barEvE10double_foo, @object
 >       .size   _ZZN3fooILi0EE3barEvE10double_foo, 4
 > _ZZN3fooILi0EE3barEvE10double_foo:
 >       .zero   4
 
 Regards
   Wolfgang
 
 -------------------------------------------------------------------------
 Wolfgang Bangerth              email:           bangerth@ticam.utexas.edu
                                www: http://www.ticam.utexas.edu/~bangerth