Because llvm is unusable for a dynamic language VM. The compile-times are too slow, it's way too big.
cranelift is also big, but has sensible staged optimizers. I.e. it doesn't behave like java or llvm.
We've been JITing using LLVM for a number of years without an obvious problem. It obviously depends on the size of the code you are wanting to JIT, but the OP was discussing a toy language as a side project, and LLVM is certainly perfect for that use case.
> cranelift is also big, but has sensible staged optimizers
LLVM gives you the freedom to decide what optimizers to use. But it's true it is too big for many applications, even if there are build options for different sizes.
This depends on your usecase i guess.
For long running numerical code (Julia) LLVM is fine but needs some work by highly skilled individuals to make it feel like a interpreted REPL when importing big code bases.
