Using rustc_codegen_cranelift as dependency?

[playXE]

I would like to create meta-tracing JIT library that will work like holyjit or RPython and there was a way of interpreting Rust MIR but now I think that it will be much simpler to interpret Cranelift IR so I'm wondering if it is possible to use rustc_codegen_cranelift to translate some Rust function MIR into Cranelift IR and then somehow obtain this IR? I've tried to look at source code but haven't found API for this

[bjorn3]

Currently codegen_fn, codegen_static, CodegenCx and driver::predefine_mono_items are private. I think those should be enough for what you want. I can make them public if you want, but I won't make any api guarantees, so make sure to pin a specific commit using rustc_codegen_cranelift = { git = "...", rev = "..." }.

[playXE]

What I've thought of is to write rustc plugin which will invoke rustc_codegen_cranelift on specified function and then save Cranelift IR in some of data sections to be interpreted and traced at runtime , is this possible?

[bjorn3]

That would also be possible. Except for the keeping it available at runtime at runtime part that would be pretty much equivalent to how cg_llvm embeds LLVM bitcode into object files.

By the way have you seen https://github.com/softdevteam/yk?

[playXE]

I have seen ykrustc, yes. It uses Intel hardware tracing which is not portable across CPUs. I belive that interpreting Cranelift IR is much easier and more portable way of doing meta-tracing JIT

[bjorn3]

I can try to implement this in a couple of days.

[playXE]

That would be awesome! Thanks!