Calyx Compiler as a Library

The Calyx compiler is separated into multiple crates that can be used independently. If you're interested in adding a new pass to the Calyx compiler or build a tool using it, your best bet is to take a look at the example in the calyx-opt library.

The calyx implements the compiler driver and plumbs together all the other crates. You mostly likely want to include the calyx-opt crate if you're working passes or just the calyx-ir crate if you're working with the IR. You'll also need calyx-frontend and calyx-utils if you're parsing frontend code.

Building the calyx Binary

The calyx binary is published using Rust's crates.io repository. It provides the compiler interface which can be used without requiring the user to build the compiler from source. The calyx binary also ships all its primitives library which is done through a somewhat complex bootstrapping process (see #1678)

1. The calyx-stdlib package pulls in the sources of all the primitives using the Rust include_str! macro.
2. The calyx binary defines a build script that depends on calyx-stdlib as a build dependency.
3. During build time, the script loads the string representation of all the primitives files and writes them to $CALYX_PRIMITIVE_DIR/primitives. If the variable is not set, the location defaults to $HOME/.calyx.
4. If (3) succeeds, the build scripts defines the CALYX_PRIMITIVES_LIB environment variable which is used when compiling the calyx crate.
5. During compilation, calyx embeds the value of this environment variable as the default argument to the -l flag. If the variable is not defined, the default value of the -l flag is ..

Users of the calyx binary can still specify a value for -l to override the default primitives file. For example, the fud configuration for the calyx stage override the value of -l to the location of the Calyx repo.