llvm-cbe VS unsafe-code-guidelines

So how does the LLVM C backend work then?

https://github.com/JuliaHubOSS/llvm-cbe

One alternative worth mentioning, though, would be the LLVM C Backend maintained by the Julia community.

If you drop "easily" and "human" (/s) from your requirements list, then the C backend for LLVM might work. Then you can choose any programming language you want that has LLVM 10-compatible frontend.

If you really must have something that compiles in C (e.g. for a platform where you only have a C compiler) there's an LLVM backend that outputs C code: https://github.com/JuliaComputingOSS/llvm-cbe

You can convert llvm bitcode to C and then use C compiler, there is such project https://github.com/JuliaComputingOSS/llvm-cbe .

I'm really surprised that the LLVM C backends have continually been resurrected then abandoned over the years. It's a good solution to this sort of thing and would enable a lot of cool stuff like Rust to weird embedded platforms. The most recent one is the Julia backend: https://github.com/JuliaComputingOSS/llvm-cbe

Check this project out: https://github.com/JuliaComputingOSS/llvm-cbe.

Well IMO it can definitely be rewritten in Julia, and to an easier degree than python since Julia allows hooking into the compiler pipeline at many areas of the stack. It's lispy an built from the ground up for codegen, with libraries like (https://github.com/JuliaSymbolics/Metatheory.jl) that provide high level pattern matching with e-graphs. The question is whether it's worth your time to learn Julia to do so.

You could also do it at the LLVM level: https://github.com/JuliaComputingOSS/llvm-cbe

For interesting takes on that, you can see https://github.com/JuliaLinearAlgebra/Octavian.jl which relies on loopvectorization.jl to do transforms on Julia AST beyond what LLVM does. Because of that, Octavian.jl beats openblas on many linalg benchmarks

You can try your luck with the "resurrected" C backend: https://github.com/JuliaComputingOSS/llvm-cbe

I don't understand why I see so many requests for LLVM-based languages to change around their backend or IR, that seems to be a huge amount of work for comparatively little benefit. The correct thing to do there is to just add support for those to LLVM.

Useful context on the Rust side is this issue [1]. It sounds like some of the author's concerns are addressed already.

[1]: https://github.com/rust-lang/unsafe-code-guidelines/issues/4...

Is this captured by one of the known soundness conflicts? If not then should consider adding it to the list.

There are some competing proposals for different memory models. Stacked borrows is the current proposal, but there are more work in the approproate WG.

Thank you /u/RalfJung for bringing formal methods to Rust, both through models like Stacked Borrows, by developing miri, and by working on unsafe-code-guidelines which aims to specify exactly what is and isn't allowed in unsafe code (surprisingly, it's an open question as 2023!)

You could imagine some way to make this safe for example automatically convert &'short &'long mut T to &'short &'short T, but it's non-trivial to prove they are safe at all, not to mention ensuring this is correctly implemented in the compiler. If you're interested there's also a discussion on whether the opposite (& & T to & &mut T) is sound here.

Agreed! MIRI is so good, it still feels like magic to me. It also comforts me that the Rust team takes improving unsafe semantics seriously, with the past Unsafe Code Guidelines WG and today's operational semantics team (t-opsem).

I think there are some aspects of this rule that are still undecided. See for example:

- https://github.com/rust-lang/unsafe-code-guidelines/issues/8...

- https://github.com/rust-lang/miri/issues/2732

C is much better specified than unsafe Rust. Some things are just not worked out yet in Rust. This may sometimes even bite very experienced devs, such as this issue with Box's aliasing semantics, which tripped up the author of left-right.