The Zürich P-system compiler generated “p-code” for a virtual stack machine which was then interpreted; that led to UCSD Pascal for the IBM PC, and to Apple Pascal.

Here’s what happens with a compiler: human-written code gets compiled into low-level machine code, creating a natively-executable result for a particular processor.

LLVM doesn’t just compile the IR to native machine code. You can also programmatically direct it to optimize the code with a high degree of granularity, all the way through the linking process.