[PATCH] D32867: Warn about archives with no symbol table

[Rafael Avila de Espindola via llvm-commits]

Rui Ueyama via Phabricator <reviews at reviews.llvm.org> writes:

> ruiu added a comment.
>
> It seems it is only me who wants it to be silent, but if we can make it virtually zero-overhead, do you still want to warn on it?

I am not fully decided. I am pretty sure that we can implement the same
logic as ar, so there will be no semantic problems.

Having a symbol table in the archive is then an optimization. If there
is a particular case where it is a significant optimization, then sure,
I think we should warn. For now it doesn't look necessary.

> Currently reading public symbols for LazyObject is serialized, but it should be easy to parallelize, so there's a large room for improvement.

If anyone has the time, an interesting thing to profile is why the
archive symbol table is not providing a measurable saving. Maybe our
archive code is slow, maybe the entire area is too fast to show up.

Cheers,
Rafael