These two functions are really useful for implementations of attributes (including attribute-target), so add the functionality.
I'm not sure which you're referring to? I don't see a bit in CGBuiltin that checks for a subset of the "Features", however it is a much smaller list (since it is only things that the compiler-rt can check). Is it perhaps more closely related to that one?
It's currently checking for a subset, but that's just because it was the subset that the compiler-rt support supported. After Craig's patch I think we can just support them all unless I'm misreading something.