Readme.md

   1 # Work in progress cranelift codegen backend for rust
   2
   3 > ⚠⚠⚠ This doesn't do much useful yet ⚠⚠⚠
   4
   5 ## Building
   6
   7 ```bash
   8 $ git clone https://github.com/bjorn3/rustc_codegen_cranelift.git
   9 $ cd rustc_codegen_cranelift
  10 $ ./prepare.sh # downloads and patches sysroot src and installs hyperfine for benchmarking
  11 $ ./test.sh
  12 ```
  13
  14 ## Usage
  15
  16 `$cg_clif_dir` is the directory you cloned this repo into in the following instruction.
  17
  18 ### Rustc
  19
  20 ```bash
  21 $ rustc -Cpanic=abort -Zcodegen-backend=$cg_clif_dir/target/debug/librustc_codegen_cranelift.so my_crate.rs
  22 ```
  23
  24 ### Cargo
  25
  26 ```bash
  27 $ RUSTFLAGS="-Cpanic=abort -Zcodegen-backend=$cg_clif_dir/target/debug/librustc_codegen_cranelift.dylib --sysroot $cg_clif_dir/build_sysroot/sysroot" cargo run
  28 ```
  29
  30 ## Not yet supported
  31
  32 * Good non-rust abi support ([scalar pair and vector are passed by-ref](https://github.com/bjorn3/rustc_codegen_cranelift/issues/10))
  33 * Checked binops ([some missing instructions in cranelift](https://github.com/CraneStation/cranelift/issues/460))
  34 * Inline assembly ([no cranelift support](https://github.com/CraneStation/cranelift/issues/444))
  35 * Varargs ([no cranelift support](https://github.com/CraneStation/cranelift/issues/212))
  36 * libstd (needs varargs and some other stuff) ([tracked here](https://github.com/bjorn3/rustc_codegen_cranelift/issues/146))
  37 * u128 and i128 ([no cranelift support](https://github.com/CraneStation/cranelift/issues/354))
  38 * SIMD ([tracked here](https://github.com/bjorn3/rustc_codegen_cranelift/issues/171))
  39
  40 ## Troubleshooting
  41
  42 ### Can't compile
  43
  44 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.
  45
  46 ### error[E0463]: can't find crate for `std` while compiling a no_std crate
  47
  48 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. :(