[llvm] ADT/Matrix: two-dimensional Container with View (PR #98893)

[Jakub Kuderski via llvm-commits]

kuhar wrote:

> The compile-time computation is very minor, and amounts to a few pointer subtractions. See MutableArrayRef<T>::slice(Begin, End - Begin); for instance.

Again, please explain why we need this to happen at compilation time.

https://github.com/llvm/llvm-project/pull/98893