[littlestymaar]

That's not a very good exemple because with BB we know the code terminates, by definition. The canonical tong-in-cheek argument is to use the Collatz conjoncture instead (but even that isn't a good example in practice: https://news.ycombinator.com/item?id=21440306)

[thr_ddv]

I'm not asking if it terminates, I'm asking when it does. After all it's not much use if the number overflows the universe.

[nine_k]

For practical reasons, it's enough to prove that it takes longer than some upper bound, say, 10 ms. The rest is not important.

[littlestymaar]

But that's not something these kinds of tools are supposed do, even with trivial functions… These tools have no idea about the run-time (and there's no way they coule, since it depends on the load you put on the hardware in parallel of running your program)

[redjamjar]

I agree. There are tools though which are specifically for determining worst-case execution time for e.g. embedded systems which can actually give accurate timing information (upto a point).

[redjamjar]

Yeah, so these tools will not tell you how long it will take to terminate --- only that it will eventually. In the vast majority of cases, that is what you want to know.