[Bug c++/42887] New: g++-3.4.6 (ssp) stack layout problem involving scopes

[thomasheinz at gmx dot net]

Consider the following sample:

#include <cstdio>

struct C
{
        int a,b,c,d,e;
        C()
        {
                printf("&e = %p\n", &e);
                e = 12345;
        }
};

int main()
{
        unsigned long long a[] = {1, 2};
        printf("a = %p, a[0] = %lld\n", a, a[0]);
        {
                C s;
        }
        printf("a = %p, a[0] = %lld\n", a, a[0]);
        unsigned long long b[] = {3, 4};
        return 0;
}

Compiling with `g++ sample.cpp` yields the following output:
a = 0xbfdb7920, a[0] = 1
&e = 0xbfdb7920
a = 0xbfdb7920, a[0] = 12345

whereas compiling with `g++ -fno-stack-protector sample.cpp` yields:
a = 0xbfc1cf90, a[0] = 1
&e = 0xbfc1cf80
a = 0xbfc1cf90, a[0] = 1

I don't have time to go into more detail but the sample should be small
enough to figure the problem out.


# gcc -v
Reading specs from /usr/lib/gcc/i686-pc-linux-gnu/3.4.6/specs
Configured with:
/var/tmp/portage/sys-devel/gcc-3.4.6-r2/work/gcc-3.4.6/configure --prefix=/usr
--bindir=/usr/i686-pc-linux-gnu/gcc-bin/3.4.6
--includedir=/usr/lib/gcc/i686-pc-linux-gnu/3.4.6/include
--datadir=/usr/share/gcc-data/i686-pc-linux-gnu/3.4.6
--mandir=/usr/share/gcc-data/i686-pc-linux-gnu/3.4.6/man
--infodir=/usr/share/gcc-data/i686-pc-linux-gnu/3.4.6/info
--with-gxx-include-dir=/usr/lib/gcc/i686-pc-linux-gnu/3.4.6/include/g++-v3
--host=i686-pc-linux-gnu --build=i686-pc-linux-gnu --disable-altivec
--enable-nls --without-included-gettext --with-system-zlib --disable-checking
--disable-werror --enable-secureplt --disable-multilib --disable-libgcj
--with-arch=i686 --enable-languages=c,c++,treelang,f77 --enable-shared
--enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu
Thread model: posix
gcc version 3.4.6 (Gentoo Hardened 3.4.6-r2 p1.6, ssp-3.4.6-1.0, pie-8.7.10)


-- 
           Summary: g++-3.4.6 (ssp) stack layout problem involving scopes
           Product: gcc
           Version: 3.4.6
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: thomasheinz at gmx dot net
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42887