Yes, the textual IR format is not an API. It's an internal implementation detail which changes somewhat rapidly. It's well specified but there's no guarantees t

Yes, the textual IR format is not an API. It's an internal implementation detail which changes somewhat rapidly. It's well specified but there's no guarantees that if you write some IR which works in LLVM 16 that it'll work as expected in LLVM 17, etc. Inside of LLVM itself IR and its related manipulation and analysis functions are "API" in so far as there's an expectation that if you change how the IR works that you won't break existing in-tree passes/that you'll work with maintainers to fix them.