Inkwell(s)

It's a New Kind of Wrapper for Exposing LLVM (Safely)

Inkwell aims to help you pen your own programming languages by safely wrapping llvm-sys. It provides a more strongly typed interface than the underlying LLVM API so that certain types of errors can be caught at compile time instead of at LLVM's runtime. This means we are trying to replicate LLVM IR's strong typing as closely as possible. The ultimate goal is to make LLVM safer from the rust end and a bit easier to learn (via documentation) and use.

Requirements

• Any Rust version released in the last year or so
• Rust Stable, Beta, or Nightly
• LLVM 3.6, 3.7, or 3.8 (3.9+ support is planned: #1)

Usage

You'll need to point your Cargo.toml to a branch and use a feature flag corresponding to a supported LLVM version:

[dependencies]
inkwell = { git = "https://github.com/TheDan64/inkwell", branch = "llvm3-7", features = ["llvm3-7"] }

Supported versions:

GitHub Branch	Feature Flag
llvm3-6	llvm3-6
llvm3-7	llvm3-7
llvm3-8	llvm3-8

In the root of your source code you will have to add an extern crate to begin using Inkwell:

extern crate inkwell;

Documentation

Documenation is automatically deployed here based on master. These docs are not yet 100% complete and only show the latest supported LLVM version due to a rustdoc issue. See #2 for more info.

Examples

Tari's llvm-sys example written in safe code¹ with Inkwell:

extern crate inkwell;

use inkwell::OptimizationLevel;
use inkwell::builder::Builder;
use inkwell::context::Context;
use inkwell::execution_engine::{ExecutionEngine, Symbol};
use inkwell::module::Module;
use inkwell::targets::{InitializationConfig, Target};
use std::error::Error;

/// Convenience type alias for the `sum` function.
///
/// Calling `sum` is innately `unsafe` because there's no guarantee it doesn't
/// do `unsafe` operations internally.
type SumFunc = unsafe extern "C" fn(u64, u64, u64) -> u64;

fn main() {
    Target::initialize_native(&InitializationConfig::default()).unwrap();
    run().unwrap();
}

fn run() -> Result<(), Box<Error>> {
    let context = Context::create();
    let module = context.create_module("sum");
    let builder = context.create_builder();
    let execution_engine = module.create_jit_execution_engine(OptimizationLevel::None)?;

    let sum = jit_compile_sum(&context, &module, &builder, &execution_engine)
        .ok_or("Unable to JIT compile `sum`")?;

    let x = 1u64;
    let y = 2u64;
    let z = 3u64;

    unsafe {
        println!("{} + {} + {} = {}", x, y, z, sum(x, y, z));
        assert_eq!(sum(x, y, z), x + y + z);
    }

    Ok(())
}

fn jit_compile_sum(
    context: &Context,
    module: &Module,
    builder: &Builder,
    execution_engine: &ExecutionEngine,
) -> Option<Symbol<SumFunc>> {
    let i64_type = context.i64_type();
    let fn_type = i64_type.fn_type(&[&i64_type, &i64_type, &i64_type], false);

    let function = module.add_function("sum", &fn_type, None);
    let basic_block = context.append_basic_block(&function, "entry");

    builder.position_at_end(&basic_block);

    let x = function.get_nth_param(0)?.into_int_value();
    let y = function.get_nth_param(1)?.into_int_value();
    let z = function.get_nth_param(2)?.into_int_value();

    let sum = builder.build_int_add(&x, &y, "sum");
    let sum = builder.build_int_add(&sum, &z, "sum");

    builder.build_return(Some(&sum));

    unsafe { execution_engine.get_function("sum").ok() }
}

¹ There are two uses of unsafe in this example because the actual act of compiling and executing code on the fly is innately unsafe. For one, there is no way of verifying we are calling get_function() with the right function signature. It is also unsafe to call the function we get because there's no guarantee the code itself doesn't do unsafe things internally (the same reason you need unsafe when calling into C).

LLVM's Kaleidoscope Tutorial

Can be found in the examples directory.

Contributing

Check out our Contributing Guide