[pavanky]

Why aren't they using LLVM :-/

[bastawhiz]

They answer this on the github:

> Unstable interfaces. An LLVM JIT is already used by Rubicon. A lot of efforts in preparation of code used by RTL insns (an environment)

https://github.com/vnmakarov/ruby/tree/rtl_mjit_branch#a-few...

[Twirrim]

llvm isn't always available, doesn't support as many architectures and doesn't always give the best performance.

The *nix philosophy has long been towards trying to provide choice wherever possible, so that people can use the tool that best meets their needs.

[jashmatthews]

The new Ruby method JIT can use either GCC or clang as the backend. It uses C as an intermediate representation.