[Bug c/53084] New: GCC cannot handle array initialization of string constant with point arithmetic properly

[Bug c/53084] New: GCC cannot handle array initialization of string constant with point arithmetic properly

[ray_linn at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

             Bug #: 53084
           Summary: GCC cannot handle array initialization of string
                    constant with point arithmetic properly
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: critical
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ray_linn@hotmail.com


Consider the following code:

#include <stdio.h>
int main() {
static const char *const aa[] = {"foo"+1};
printf("aa[0] = %s\n",aa[0]);
return 0;
}

 works fine on GCC 4.5.2 and 4.6.1
C:\work>gcc --version
gcc (tdm-1) 4.5.2
Copyright (C) 2010 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


C:\work>gcc a.c -oa.exe

C:\work>a
aa[0] = oo


C:\work>gcc --version
gcc (tdm-1) 4.6.1
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


C:\work>gcc a.c -oa.exe

C:\work>a
aa[0] = oo

On GCC 4.7.0, it fails with segmentation fault.

C:\work>gcc --version
gcc (GCC) 4.7.0
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


C:\work>gcc a.c -oa.exe

C:\work>a

(error dialog)


Please go there to find the original bug threads: 
http://bugs.ruby-lang.org/issues/6333

[Bug c/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |wrong-code
   Last reconfirmed|                            |2012-04-23
     Ever Confirmed|0                           |1
            Summary|GCC cannot handle array     |[4.7/4.8 Regression] GCC
                   |initialization of string    |cannot handle array
                   |constant with point         |initialization of string
                   |arithmetic properly         |constant with point
                   |                            |arithmetic properly
   Target Milestone|---                         |4.7.1
           Severity|critical                    |normal

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-04-23 10:22:34 UTC ---
Confirmed.

[Bug c/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[ktietz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

--- Comment #2 from Kai Tietz <ktietz at gcc dot gnu.org> 2012-04-23 10:25:05 UTC ---
I can confirm it with trunk version for -O0, too.

Issue is that there seems to be a wrong-code generation bug for O0 and
read-only section data.

...
        movq    aa.2567(%rip), %rax
        movq    %rax, %rdx
        leaq    .LC0(%rip), %rcx
        call    printf
...

...
        .data
        .align 8
aa.2567:
        .section .rdata,"dr"
.LC1:
        .ascii "foo\0"
        .quad   .LC1+1
...

The aa.2567 label is emitted in data, but its definition in .rdata

[Bug c/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-23 16:47:32 UTC ---
Can't reproduce on x86_64-linux, please fill in Target.

[Bug c/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[ktietz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

Kai Tietz <ktietz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|*-*-mingw*                  |x86_64-*-* i686-*-*

--- Comment #4 from Kai Tietz <ktietz at gcc dot gnu.org> 2012-04-23 17:19:27 UTC ---
(In reply to comment #3)
> Can't reproduce on x86_64-linux, please fill in Target.

Hmm, I can.  For x86_64-unknown-linux-gnu using -O0 as optimization option, I
see for this test

aa.2162:
.LC1:
     .string "foo"
     .quad .LC1+1

which is wrong, too.

[Bug c/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-23 17:45:55 UTC ---
I don't see that on the trunk:
    .section    .rodata
.LC1:
    .string    "foo"
    .align 8
    .type    aa.1706, @object
    .size    aa.1706, 8
aa.1706:
    .quad    .LC1+1
Ah, but looking at current 4.7, I can reproduce that.  Will look at it.

[Bug middle-end/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |jakub at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-23 19:50:40 UTC ---
Created attachment 27226
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27226
gcc47-pr53084.patch

Untested fix.

[Bug middle-end/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[ktietz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

--- Comment #7 from Kai Tietz <ktietz at gcc dot gnu.org> 2012-04-23 20:14:05 UTC ---
This patch fixes issues for noticed for mingw targets on trunk and for 4.7.

[Bug middle-end/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-24 06:07:34 UTC ---
Author: jakub
Date: Tue Apr 24 06:07:30 2012
New Revision: 186742

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186742
Log:
    PR middle-end/53084
    * varasm.c (compute_reloc_for_constant): Handle ADDR_EXPR
    of MEM_REF.
    (output_addressed_constants): Likewise.

    * gcc.c-torture/execute/pr53084.c: New test.

Added:
    trunk/gcc/testsuite/gcc.c-torture/execute/pr53084.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/varasm.c

[Bug middle-end/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-24 06:11:00 UTC ---
Author: jakub
Date: Tue Apr 24 06:10:53 2012
New Revision: 186745

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186745
Log:
    PR middle-end/53084
    * varasm.c (compute_reloc_for_constant): Handle ADDR_EXPR
    of MEM_REF.
    (output_addressed_constants): Likewise.

    * gcc.c-torture/execute/pr53084.c: New test.

Added:
    branches/gcc-4_7-branch/gcc/testsuite/gcc.c-torture/execute/pr53084.c
Modified:
    branches/gcc-4_7-branch/gcc/ChangeLog
    branches/gcc-4_7-branch/gcc/varasm.c

[Bug middle-end/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-24 06:14:43 UTC ---
Author: jakub
Date: Tue Apr 24 06:14:37 2012
New Revision: 186746

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186746
Log:
    PR middle-end/53084
    * varasm.c (compute_reloc_for_constant): Handle ADDR_EXPR
    of MEM_REF.
    (output_addressed_constants): Likewise.

    * gcc.c-torture/execute/pr53084.c: New test.

Added:
    branches/gcc-4_6-branch/gcc/testsuite/gcc.c-torture/execute/pr53084.c
Modified:
    branches/gcc-4_6-branch/gcc/ChangeLog
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog
    branches/gcc-4_6-branch/gcc/varasm.c

[Bug middle-end/53084] [4.7/4.8 Regression] GCC cannot handle array initialization of string constant with point arithmetic properly

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53084

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-24 09:40:17 UTC ---
Should be fixed now.