It's more an fun educational overview of the new FFM API.

I can't think of many actual use-cases where you'd want to use the LLVM JIT over those built-in to HotSpot.

Interfacing with existing LLVM-based systems, writing a very tight inner loop using LLVM where you absolutely need LLVM-like performance, or creating a compiler that targets LLVM using Java would be the main "real-world" use-cases.