qbe-rs VS ubpf

You can try buildling you own backend like llvm. A good example or starting point is probably QBE since it is extremely small but very functional.

How big is the whole backend? I've heard that it is small but I wanted to compare it to QBE which is around 8 KLoC and it is quite interesting too.

I think QBE might be what you're looking for?

https://c9x.me/compile/

As far as I know, there is QBE, which is actually kinda underrated, and Cranelift, mainly designed for JIT compilation

Before that, I had spent a bit of time working with QBE, which is much simpler and really easy to write a frontend for. I switched to libgccjit though, because I got frustrated with a few of the things lacking from QBE (like the ability to easily keep track of where different variables live on the stack). I think for many hobby language projects, QBE would be a good option (my project was off the ground very fast using QBE, and I got pretty far before I ran into limitations I couldn't easily work around).

If one of your parameters is size/complexity of the backend and you prefer something smaller, have a look at qbe and cwerg

The alternatives are generally hidden inside of another compiler. The big exception seems to be qbe (https://c9x.me/compile/) however since the author appears to have written this code without peer review, it's not easy to read it's source code.

So my question is this: if a backend like QBE (~12k Loc) was added to Zig and Zig only had to compile Zig code (no C, etc) for that QBE backend -- about how many LoC would that Zig need to be?

GCC is written in C++ these days, so something like QBE(https://c9x.me/compile/) would be needed.

The usual recommendation have been given. Now for more touristic approach what I would like to use if given excuse and time. All those options are mostly written in C:

- QBE [1] - small compiler backend with nice IL

- DynASM [2] - IIUC the laujit's backend, that can and is used by other languages

- uBPF - Userspace eBPF VM. Depending on your DSL the eBPF toolchain could fit your use-case, but this would probably be the biggest excursion.

[1] https://c9x.me/compile/

[2] https://luajit.org/dynasm.html

[3] https://github.com/iovisor/ubpf

This may be entirely irrelevant to what you are looking for, but a good widely used finite register-based VM is the eBPF VM in the Linux Kernel. The IOVisor uBPF project (https://github.com/iovisor/ubpf) is a version of the VM in user space.