Using LLVM and Sulong for Language C Extensions

Many languages such as Ruby, Python and JavaScript support extension modules written in C, either for speed or to create interfaces to native libraries. Ironically, these extensions can hold back performance of the languages themselves because the native interfaces expose implementation details about how the language was first implemented, such as the layout of data structures. In JRuby+Truffle, an implementation of Ruby, we are using the Sulong LLVM bitcode interpreter to run C extensions on the JVM. By combining LLVM's static optimizations with dynamic compilation, Sulong is fast, but Sulong also gives us a powerful new tool - it allows us to abstract from normal C semantics and to appear to provide the same native API while actually mapping it to our own alternative data structures and implementation. We'll demonstrate Sulong and how we're using it to implement Ruby C extensions.