[llvm] [Semilattice] Introduce for dataflow analysis with KnownBits (PR #177616)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> > I don't know what's causing it - but the make_filter_range call inside filter_range is stripping the ExcludeFn callback - leaving an Empty std::function
> 
> Thanks Simon, that's helpful: I think that maybe capturing the std::function by ref isn't working: I've pushed a fix to capture by value, which hopefully fixes the issue.

The Windows problem seems to be fixed now. For future reference: MSVC seems to have an issue with capturing a std::function, either by value or by reference, in a lambda; the fix is to change it to a function_ref.

If we can now take a look at the patch, that would be good. More specifically: I think I have followed @nikic's guidance, and started copying over functions from ValueTracking, but I'm not sure if we should continue with this process and complete a full working example migrating one use-site, as there is already a lot of visible code duplication? I'm not able to think of alternatives though.

https://github.com/llvm/llvm-project/pull/177616