add warning if target always segfaults

[bchurchill]

Have stoke print a big warning if the target always segfaults on its inputs. This is a common reason for a search to fail.

[stefanheule]

Sounds like a great feature. I'm curious though as to why search wouldn't succeed trivially (with something that also just segfaults)?

[bchurchill]

That's exactly what happens. It basically just finds the most performant program that segfaults, but it will happily spend some time doing this. I'm tried of forgetting to double-check this :P

(edit: in particular, it likes to spend time doing loop optimizations: can I move the segfault out of the loop, and then shortcut the loop itself? lol)

[stefanheule]

Ok, that sounds right. Your original message said this would be a common way for search to "fail", which is what surprised me. I expected search to "succeed", but in a useless way (with a program that always segfaults).

Anyway, sounds like a useful warning.