FFI Interface for the LLVM 8 C API

This package provides FFI bindings/wrapper for the LLVM C API. Not all of the C API is currently supported by most of the core functionality is there. Added additional methods will be done as needed and Pull Requests are welcome!

Usage

Install the package via NPM:

npm i --save llvm-ffi

You obviously have to have an installation of LLVM 8, and have installed/compiled a version of libLLVM.dylib.

This library loads the path to the LLVM from the environment via the variable LLVM_PATH.

Once LLVM is in a valid location simply require this module:

const { libLLVM } = require('llvm-ffi');

And any LLVM C API call that has a binding can be called directly:

const aModule = libLLVM.LLVMModuleCreateWithName('mymodule');
const theName = libLLVM.LLVMGetModuleIdentifier(aModule);

console.log('LLVM module name:', theName); // mymodule

// and since these are C bindings you are responsible for the memory management

libLLVM.LLVMDisposeModule(aModule);

Example

Also examples/main.js for a runnable version.

To build a main function in LLVM thats callable when built into a binary:

const { libLLVM, enums } = require('llvm-ffi');

const moduleRef = libLLVM.LLVMModuleCreateWithName('main_module');
const builderRef = libLLVM.LLVMCreateBuilder();

// create params for main
const params = [
  libLLVM.LLVMInt32Type(),
  libLLVM.LLVMPointerType(libLLVM.LLVMPointerType(libLLVM.LLVMInt8Type(), 0), 0)
];

// create the function prototype
const funcType = libLLVM.LLVMFunctionType(libLLVM.LLVMVoidType(), params, params.length, 0);
const func = libLLVM.LLVMAddFunction(moduleRef, 'main', funcType);

libLLVM.LLVMSetLinkage(func, enums.LLVMLinkage.LLVMExternalLinkage);

// name the params
const argc = libLLVM.LLVMGetParam(func, 0);
const argsv = libLLVM.LLVMGetParam(func, 1);

libLLVM.LLVMSetValueName(argc, 'argc');
libLLVM.LLVMSetValueName(argsv, 'argsv');

// build body of the function
const entry = libLLVM.LLVMAppendBasicBlock(func, 'entry');
libLLVM.LLVMPositionBuilderAtEnd(builderRef, entry);
libLLVM.LLVMBuildRetVoid(builderRef);

// print out the LLVM IR for this module
console.log(libLLVM.LLVMPrintModuleToString(moduleRef));

// clean up
libLLVM.LLVMDisposeBuilder(builderRef);
libLLVM.LLVMDisposeModule(moduleRef);

And run it:

node main.js

And see the output of the LLVM IR created by the library:

; ModuleID = 'main_module'
source_filename = "main_module"

define void @main(i32 %argc, i8** %argsv) {
entry:
  ret void
}

Now go build a compiler!