[Bug rtl-optimization/57343] New: wrong code on x86_64-linux at -Os and above

[dhazeghi at yahoo dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57343

            Bug ID: 57343
           Summary: wrong code on x86_64-linux at -Os and above
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dhazeghi at yahoo dot com

The following code is miscompiled on x86_64-linux at -Os and above with gcc
trunk and at -O2 and above with gcc 4.8.  It outputs 0 rather than 4 as it
should.  It works correctly with gcc 4.7.

$ gcc-trunk -v
gcc version 4.9.0 20130520 (experimental) [trunk revision 199099] (GCC) 
$ gcc-trunk -O1 wrong.c 
$ ./a.out 
4
$ gcc-4.7 -Os wrong.c 
$ ./a.out 
4
$ gcc-trunk -Os wrong.c 
$ ./a.out 
0
$
------------------------------
int printf (const char *, ...);
int a[6];
int b, c, d, e;
int f[10] = { 0, 0, 0, 0, 0, 1075L };

int *g = &f[5];
char h;
unsigned i;
void
fn1 (int p1)
{
    b = a[p1];
}

int
main ()
{
    for (; e < 6; e++)
        a[e] = e;
    i = -14;
    for (; i >= 8; i++)
    {
        d = --c;
        h = d * 100L;
        if (h);
        else
        {
            *g = 0;
            break;
        }
    }

    fn1 (f[5] >> 8 & 15);
    printf ("%d\n", b);

    return 0;
}