[klodolph]

> Compilers like XLC will actually even assume unsigned loop induction variables will not ovefrlow at O3

That's not exactly fair. The C standard guarantees that unsigned variables will overflow by wrapping, so if the compiler assumes such a loop won't terminate, it is not conformant.

[DannyBee]

That's exactly the point: they cheat, because it makes code faster except in the small percent of code it breaks.

Let us all now bow our heads to the almighty SPEC gods ...