On Sun, 2009-11-29 at 16:00 -0500, me22 wrote: > > What about using (long)((unsigned long)a + (unsigned long)b) or > something to get around the UB? Type casting may be ineffective. On x86-64 in 64-bit mode gcc (4.4.1) generates unsigned addition. That is, x = a + b; is implemented as leaq (%rdx,%rax), %rbx The leaq instruction has no effect on the rflags register. Hence, even if we could test the overflow bit, it would not be accurate. --Bob
