[Bug c++/31309] g++ 4.2.0 amd64 codegen issue with -O0. 6 byte assignment at end of structure reads/writes past end of structure causing SEGV when that memory is not accessable.

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2007-03-22 10:03 -------
Confirmed.  The program segfaults also with -fno-inline -O[12] and we create
very
interesting code for XXX::Initialize:

_ZN3XXX10InitializeEi:
.LFB4:
        movq    (%rdi), %rax
        movslq  %esi,%rsi
        pushq   %rbx
.LCFI0:
        movq    (%rax,%rsi,8), %rbx
        movb    $0, 8(%rbx)
        movb    $0, 9(%rbx)
        call    _Z17INIT_6_BYTES_ZEROv
        movq    10(%rbx), %rdx
        movzbl  %al, %esi
        movzbl  %ah, %ecx
        xorb    %dl, %dl
        orq     %rsi, %rdx
        movq    %rax, %rsi
        movb    %cl, %dh
        movq    %rax, %rcx
        andl    $4278190080, %esi
        andl    $16711680, %ecx
        andq    $-16711681, %rdx
        orq     %rcx, %rdx
        movabsq $-4278190081, %rcx
        andq    %rcx, %rdx
        movabsq $1095216660480, %rcx
        orq     %rsi, %rdx
        movq    %rax, %rsi
        andq    %rcx, %rsi
        movabsq $-1095216660481, %rcx
        andq    %rcx, %rdx
        movabsq $280375465082880, %rcx
        andq    %rcx, %rax
        orq     %rsi, %rdx
        movabsq $-280375465082881, %rcx
        andq    %rcx, %rdx
        orq     %rax, %rdx
        movq    %rdx, 10(%rbx)
        popq    %rbx
        ret


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-03-22 10:03:14
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31309