Brussels / 3 & 4 February 2018


Easy::jit: just-in-time compilation for C++

Finally! The wonders of just-in-time compilation are available in C++: runtime specialization, code derived from data structures, and many more! Easy::jit provides a simple interface over the LLVM's just-in-time compiler. No specific compiler knowledge is required!

A single function call serves as the specification for the generated code and entry point for the just-in-time compiler. The user can precisely control when the compilation is launched, do it in a separate thread if desired or cache the generated code, and manage the lifetime of the generated code.

int baz(int a, int b) { ... }

int foo(int a) {

// compile a specialized version of baz 
auto baz_2 = easy::jit(baz, _1, 2); // mimics std::bind
return baz_2(a); // run !


The call to easy::jit generates a mix of compiler directives and runtime library calls, that are picked up by an especial LLVM pass. This pass embeds metadata and bitcode versions of the C++ code in the resulting binary. A runtime library parses the metadata and bitcode, and generates assembly code based on the runtime library calls in the code.

This talk introduces the Easy::jit library, the approach of a compiler-assisted library, its current limitations, and tries to gather feedback from experts and potential users.


Photo of Juan Manuel Martinez Caamaño Juan Manuel Martinez Caamaño