[Locke1689]

It depends on what you mean by parallel.

Certainly the Roslyn C# compiler is highly parallel. All files are parsed in parallel, then all classes are bound (semantically analyzed) in parallel, then the IL serialization phase is sequential.

[bootload]

"It depends on what you mean by parallel."

Across different machines, not cores on ^a^ chip?

[Locke1689]

I wouldn't say that's what most people mean by parallel, but in that case I think you're better off building a layer on top of the compiler for that.

For instance, provided deterministic compilation you could keep a networked cache of compiled libraries that would be delivered as needed.

Trying to be network-parallel at any finer level is probably a waste of time -- network and (de)serialization overhead would eat away all the advantages.