rust/Readme.md

Work in progress cranelift codegen backend for rust

⚠⚠⚠ This doesn't do much useful yet ⚠⚠⚠

Building

$ git clone https://github.com/bjorn3/rustc_codegen_cranelift.git
$ cd rustc_codegen_cranelift
$ ./prepare.sh # downloads and patches sysroot src and installs hyperfine for benchmarking
$ ./test.sh

Usage

$cg_clif_dir is the directory you cloned this repo into in the following instruction.

Rustc

$ rustc -Cpanic=abort -Zcodegen-backend=$cg_clif_dir/target/debug/librustc_codegen_cranelift.so my_crate.rs

Cargo

$ RUSTFLAGS="-Cpanic=abort -Zcodegen-backend=$cg_clif_dir/target/debug/librustc_codegen_cranelift.dylib --sysroot $cg_clif_dir/build_sysroot/sysroot" cargo run

Not yet supported

• Good non-rust abi support (scalar pair and vector are passed by-ref)
• Checked binops (some missing instructions in cranelift)
• Inline assembly (no cranelift support)
• Varargs (no cranelift support)
• libstd (needs varargs and some other stuff) (tracked here)
• u128 and i128 (no cranelift support)
• SIMD (tracked here)

Troubleshooting

Can't compile

Try updating your nightly compiler. You can try to use an nightly a day or two older if updating rustc doesn't fix it. If you still can't compile it, please fill an issue.

error[E0463]: can't find crate for std while compiling a no_std crate

If you use RUSTFLAGS to pass -Zcodegen-backend to rustc, cargo will compile build-dependencies with those flags too. Because this project doesn't support libstd yet, that will result in an error. I don't know of any way to fix this. :(