rustc_codegen_gcc VS gccrs

Alternatively, there's another initiative called codegen_gcc which is about using GCC as a backend for the rustc compiler. It's (much) more advanced in Rust support, but I am not sure how easy it would be to use a modified libgccjit from there.

In addition to what others have said about platform support, Rust is also on its way to gaining more platform support through rustc_codegen_gcc, the GCC codegen backend for rustc, as an alternative to the LLVM backend. That means many of the platforms GCC supports will suddenly become available with Rust.

Yeah, rustc_codegen_gcc is a GCC backend for rustc, and its making a lot of good regular progress.

gcc-rs is one of two projects for bringing Rust to gcc. gcc-rs is the more ambitious of the two, with an entirely new frontend. There is also rustc_codegen_gcc (https://github.com/rust-lang/rustc_codegen_gcc) that keeps the rustc frontend, and only swaps out LLVM for GCC at the codegen stage.

Fixing unwinding in release mode is still ungoing. I could use some help here, so anyone with some understanding of unwinding, landing pads or GCC, please come on this issue to discuss this.

Additionally, there is gcc codegen for rustc (https://github.com/rust-lang/rustc_codegen_gcc), which is not a compiler per se, but an alternative code generator, with more architectures supported and other nice things. It's also coming along, but there's still a lot of work to do there too. There's also Cranelift codegen (https://github.com/bjorn3/rustc_codegen_cranelift), which is designed to make debug builds faster, but this is not as exciting/useful as the other 2.

Good idea. I added the tag "help wanted" to the issue.

Also, there are indeed ABI issues, e.g. for 128-bit integers and NaN.

I'm excited about both the backend & the frontend.

There is also a project for rustc to use GCC instead of LLVM for codegen.

https://github.com/rust-lang/rustc_codegen_gcc

There is a Rust front-end for GCC that is under active development [1]. If the chip vendors are not willing to develop and upstream a LLVM back-end then they can feel free to start contributing to it.

[1] https://rust-gcc.github.io/

That's why gccrs doesn't even consider lifetime checking a part of the language (they plan to use Polonius, too).

There's ongoing work on a Rust front-end for GCC (https://github.com/Rust-GCC/gccrs). Bit barebones right now -- ie, even core doesn't compile -- but there's funding, demand, and regular progress, so it'll only get better from there. Once gccrs can compile core, it should be ready to compile most of Rust, and thus if you've taught the calling conventions for C to GCC, you're golden.

I recommend checking out the GCC Rust frontend project.

That is what theyre refering to, yes. The GitHub is named https://github.com/Rust-GCC/gccrs

- But this misses so much extra context information

3. Macro invocations there are really subtle rules on how you treat macro invocations such as this which is not documented at all https://github.com/Rust-GCC/gccrs/blob/master/gcc/rust/expan...

Some day I personally want to write a blog post about how complicated and under spec'd Rust is, then write one about the stuff i do like it such as iterators being part of libcore so i don't need reactive extensions.

(Speaking of which, Rust-GCC (or gcc-rs or gccrs or whichever other of their names they decide is the primary one) isn't even going to be a complete C++ implementation. Their plan is to implement enough to compile Polonius (the NLL 2.0 borrow checker being developed in Rust for rustc) and then share that since borrow-checking isn't necessary for codegen... only to identify and reject invalid programs... making the C++ portion of it not that different in scope from mrustc.)

That bridge will be crossed with gccrs (compiling Rust with gcc directly, coming next month with GCC 13) and rust_codegen_gcc (rustc frontend, GCC backend, works now but just doesn’t yet have an “easy” setup)