# cat empty-loop.c

long f()
{
    long i, ret = 0;
    for (i = 0; i < 1000000000; i++)
        ret++;
    return ret;
}

# gcc empty-loop.c -O2 -S && cat empty-loop.s

f:
        pushl   %ebp
        movl    $999999999, %eax
        movl    %esp, %ebp
        .p2align 4,,15
.L5:
        decl    %eax
        jns     .L5
        popl    %ebp
        movl    $1000000000, %eax
        ret

source # http://gcc.gnu.org/ml/gcc-help/2004-11/msg00169.html