[Bug c/40693] New: atomic built-ins malfunction with 64-bit and optimization

[m dot rosellini at f5 dot com]

#include <stdint.h>
#include <stdio.h>

int
main(int ac, char *av[])
{
    int64_t x;
    int64_t like_a_constant = -1;
    int64_t unlike_a_constant = -1;

    if (ac == 0) unlike_a_constant = 5;

    x = 0;
    __sync_add_and_fetch(&x, like_a_constant);
    printf("%016llx\n", x);

    x = 0;
    __sync_add_and_fetch(&x, unlike_a_constant);
    printf("%016llx\n", x);
}

Expected result:
ffffffffffffffff
ffffffffffffffff

Actual result:
00000000ffffffff
ffffffffffffffff


-- 
           Summary: atomic built-ins malfunction with 64-bit and
                    optimization
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: m dot rosellini at f5 dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40693