[Bug c++/40333] New: g++ does not align static variables properly

[Bug c++/40333] New: g++ does not align static variables properly

[gccsse at mailinator dot com]

The following SSE2 code crashes because the non-static global variable breaks
the alignment of the static data section.

align.cpp:

#include <emmintrin.h>
int nonstatic_padding;
static int static_padding[3];
static __attribute__((aligned(16))) __m128i sse_data;
int main() {
    static_padding[0] = 1234;
    sse_data = _mm_set1_epi32(123);
    return 0;
}

The example uses SSE2 because that's how I discovered the bug and because it
results in a nice crash, though I don't think it's essential at all.

Results:
- crashes (even when static_padding is removed)
- no longer crashes when removing nonstatic_padding (even when static_padding
is present)
- no longer crashes when making sse_data non-static

Tested with:
g++-4 (GCC) 4.3.2 20080827 (beta) 2
and g++ (GCC) 3.4.4 (cygming special, gdc 0.12, using dmd 0.125)
(I know they're a bit old, but Cygwin doesn't provide more recent binaries)

If you rename the file to align.c gcc compiles it correctly and the program
does not crash (gcc places static variables before non-static ones, unlike
g++).


-- 
           Summary: g++ does not align static variables properly
           Product: gcc
           Version: 4.3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: gccsse at mailinator dot com
 GCC build triplet: i686-pc-cygwin
  GCC host triplet: i686-pc-cygwin
GCC target triplet: i686-pc-cygwin


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40333

[Bug c++/40333] g++ does not align static variables properly

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2009-06-03 21:26 -------


*** This bug has been marked as a duplicate of 37216 ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40333

[Bug c++/40333] g++ does not align static variables properly

[rogerdpack at gmail dot com]

------- Comment #2 from rogerdpack at gmail dot com  2009-08-24 04:38 -------
(In reply to comment #0)
> The following SSE2 code crashes because the non-static global variable breaks
> the alignment of the static data section.

Is this fixed if you use 4.5.0?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40333

[Bug c++/40333] g++ does not align static variables properly

[dannysmith at users dot sourceforge dot net]

------- Comment #3 from dannysmith at users dot sourceforge dot net  2009-08-24 06:15 -------
(In reply to comment #2)
> (In reply to comment #0)
> > The following SSE2 code crashes because the non-static global variable breaks
> > the alignment of the static data section.
> 
> Is this fixed if you use 4.5.0?
> 
This is fixed with 4.5.0 and a recent binutils (Nick Clifton's patch to GAS was
commuitted on 2008-09-03)
Danny


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40333