roc/compiler/builtins/bitcode

Bitcode for Builtins

How it works

Roc's builtins are implemented in the compiler using LLVM only. When their implementations are simple enough (e.g. addition), they can be implemented directly in Inkwell.

When their implementations are complex enough, it's nicer to implement them in a higher-level language like Zig, then compile the result to LLVM bitcode, and import that bitcode into the compiler.

Compiling the bitcode happens automatically in a Rust build script at compiler/builtins/build.rs. Then builtins/src/bitcode/rs staticlly imports the compiled bitcode for use in the compiler.

You can find the compiled bitcode in target/debug/build/roc_builtins-[some random characters]/out/builtins.bc. There will be two directories like roc_builtins-[some random characters], look for the one that has an out directory as a child.

The bitcode is a bunch of bytes that aren't particularly human-readable. If you want to take a look at the human-readable LLVM IR, look at target/debug/build/roc_builtins-[some random characters]/out/builtins.ll

Calling bitcode functions

Use the call_bitcode_fn function defined in llvm/src/build.rs to call bitcode funcitons.

Developing

To add a builtin, just add it to src/main.zig. For anything you add, you must add tests for it! Not only does to make the builtins more maintainable, it's the the easiest way to test these functions on Zig. To run the test, run

zig build test