[Bug testsuite/97803] New: c-c++-common/asan/pointer-compare-1.c assumes variable placement

[Bug testsuite/97803] New: c-c++-common/asan/pointer-compare-1.c assumes variable placement

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97803

            Bug ID: 97803
           Summary: c-c++-common/asan/pointer-compare-1.c assumes variable
                    placement
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: testsuite
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
  Target Milestone: ---

c-c++-common/asan/pointer-compare-1.c has

char global1[100] = {}, global2[100] = {}; 
char __attribute__((used)) smallest_global[5] = {}; 
char small_global[7] = {}; 
char __attribute__((used)) little_global[10] = {}; 
char __attribute__((used)) medium_global[4000] = {}; 
char large_global[5000] = {}; 
char __attribute__((used)) largest_global[6000] = {}; 

They are used to has layout:

0000000000404380 B largest_global
0000000000405b20 B large_global
0000000000406ee0 B medium_global
0000000000407ea0 B little_global
0000000000407ee0 B small_global
0000000000407f20 B smallest_global
0000000000407f60 B global2
0000000000408000 B global1
00000000004080e0 B __odr_asan.largest_global
00000000004080e1 B __odr_asan.large_global
00000000004080e2 B __odr_asan.medium_global
00000000004080e3 B __odr_asan.little_global
00000000004080e4 B __odr_asan.small_global
00000000004080e5 B __odr_asan.smallest_global
00000000004080e6 B __odr_asan.global2
00000000004080e7 B __odr_asan.global1

With SHF_GNU_RETAIN change:

https://gitlab.com/x86-gcc/gcc/-/tree/users/hjl/elf/shf_retain

the new layout become:

0000000000404380 B large_global
0000000000405740 B small_global
0000000000405780 B global2
0000000000405820 B global1
0000000000405900 B __odr_asan.largest_global
0000000000405901 B __odr_asan.large_global
0000000000405902 B __odr_asan.medium_global
0000000000405903 B __odr_asan.little_global
0000000000405904 B __odr_asan.small_global
0000000000405905 B __odr_asan.smallest_global
0000000000405906 B __odr_asan.global2
0000000000405907 B __odr_asan.global1
0000000000405920 B largest_global
00000000004070c0 B medium_global
0000000000408080 B little_global
00000000004080c0 B smallest_global

and test fails.

[Bug testsuite/97803] c-c++-common/asan/pointer-compare-1.c assumes variable placement

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97803

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Does it work if you add -fno-toplevel-reorder?  SHF_GNU_RETAIN should preserve
the order of vars even if 'used' then.

[Bug testsuite/97803] c-c++-common/asan/pointer-compare-1.c assumes variable placement

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97803

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
                 CC|                            |marxin at gcc dot gnu.org
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2020-11-12

--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
I can take care of this.

[Bug testsuite/97803] c-c++-common/asan/pointer-compare-1.c assumes variable placement

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97803

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Richard Biener from comment #1)
> Does it work if you add -fno-toplevel-reorder?  SHF_GNU_RETAIN should
> preserve the order of vars even if 'used' then.

Linker will reorder section layout when SHF_GNU_RETAIN is used.

[Bug testsuite/97803] c-c++-common/asan/pointer-compare-1.c assumes variable placement

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97803

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 49552
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49552&action=edit
A patch

This works with SHF_GNU_RETAIN.

[Bug testsuite/97803] c-c++-common/asan/pointer-compare-1.c assumes variable placement

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97803

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
           Assignee|marxin at gcc dot gnu.org          |unassigned at gcc dot gnu.org

--- Comment #5 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to H.J. Lu from comment #4)
> Created attachment 49552 [details]
> A patch
> 
> This works with SHF_GNU_RETAIN.

Please install the patch H.J.

[Bug testsuite/97803] c-c++-common/asan/pointer-compare-1.c assumes variable placement

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97803

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by H.J. Lu <hjl@gcc.gnu.org>:

https://gcc.gnu.org/g:9dbf8dc7a96a8020e0ee05926ef7a3f976e9c318

commit r11-5054-g9dbf8dc7a96a8020e0ee05926ef7a3f976e9c318
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Nov 11 15:54:00 2020 -0800

    pointer-compare-1.c: Add __attribute__((used))

    c-c++-common/asan/pointer-compare-1.c assumes the certain order for
    variable placement.  Add __attribute__((used)) to avoid variable
    placement changes due to SHF_GNU_RETAIN.

            PR testsuite/97803
            * c-c++-common/asan/pointer-compare-1.c (global1): Add
            __attribute__((used))
            (global2): Likewise.
            (small_global): Likewise.
            (large_global): Likewise.

[Bug testsuite/97803] c-c++-common/asan/pointer-compare-1.c assumes variable placement

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97803

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |11.0

--- Comment #7 from H.J. Lu <hjl.tools at gmail dot com> ---
Fixed.