Question

Is it theoretically and/or practically possible to compile native c++ to some sort of intermediate language which will then be compiled at run time?

Along the same lines, is “portable” the term used to denote this?

Answer 1

LLVM which is a compiler infrastructure parses C++ code, transforming it to an intermediate language called LLVM IR (IR stands for Intermediate Representation) which looks like high-level assembly language. It is a machine independent language. Generating IR is one phase. In the next phase, it passes through various optimizers (called pass). which then reaches to third phase which emits machine code (i.e machine dependent code).

It is a module-based design; output of one phase (module) becomes input of another. You could save IR on your disk, so that the remaining phases can resume later, maybe on entirely different machine!

So you could generate IR and then do rest of the things on runtime? I’ve not done that myself, but LLVM seems really promising.

Here is the documentation of LLVM IR:

• LLVM Language Reference Manual

This topic on Stackoverlow seems interesting, as it says,

• LLVM advantages:
  • JIT – you can compile and run your code dynamically.

And these articles are good read:

• The Design of LLVM (on drdobs.com)

• Create a working compiler with the LLVM framework, Part 1