shouldn't use uwtable on functions that aren't exported

[thestinger]

This is only useful to prevent the ABI from changing depending on whether a function is nounwind or not.

[thestinger]

This is a bit trickier than I had thought... since functions can be passed a function that throws, or parametrized with a type that can throw in a method call.

[brson]

I imagine that any frame that may end up unwinding needs uwtable. In Rust that is almost all frames. There may be some glues that don't need to unwind. I'm not sure how actionable this is. @thestinger do you still think there's something that can be done here?

[thestinger]

@brson: no, I think it wasn't a great idea after all, closing :)

LLVM is able to figure out when it isn't necessary for the internal functions anyway afaict