[llvm] [llubi] Initial support for vector predication intrinsics (PR #212093)

[Luke Lau via llvm-commits]

lukel97 wrote:

> I just noticed most of the trivial vp intrinsics will be removed :( https://discourse.llvm.org/t/rfc-remove-trivial-vp-intrinsics/90972

Yeah, they're not used in-tree or supported by any target other than VE which is mostly unmaintained. However there's no plans to remove `vp.merge`, since it has different semantics to `select`. It would be useful to have support for it in llubi still

https://github.com/llvm/llvm-project/pull/212093