Question

This question is about definitions, semantics.

I understand the general concept of interpretation, translating source to machine code in real-time, or into an intermediate cache which is later “compiled” in real time or just before run time, etc.

Is there a semantic distinction made between the source > byte code translation step, and the byte code > machine code translation step? Do people typically refer to the first part as “interpretation” and the second step as “compilation”. Please don’t misunderstand, I am not asking for a definition of compilation outside the scope of dynamic languages. That is another topic.

Additionally, is it futile to make a semantic distinction between these two steps, due to the large number of interpreters that implement so many different techniques?

Answer 1

Typically, interpretation means the execution of a program in an arbitrary form (plain sourcecode, abstract syntax tree (AST), bytecode, …) by an interpreter.

Some virtual machines make heavy use of JITs (just in time compilers) which translate (compile) the intermediate representation of a program to native machine code. This is definitely a form of compilation.

Also, some VMs do several phases of compilation: At first, an AST is compiled to bytecode, which can later on be compiled to machine code.

I would say, compilation means basically a transformation of one intermediate representation to the next representation.