Consider speeding up compile times by caching ASTs

[jtenner]

When using the compiler to compile multiple test suites in as-pect, there are many shared common files that need to be re-parsed and an AST needs to be generated every single time the software calls asc.main().

I was curious if there was a way to cache the entire AST of a given file instead of running each file through the parser every single time a module needs to compile?

I remember that @willemneal managed to do something like this and it sped up as-pect cli run-times by a good three seconds over the course of 10 compilations on my local PC. (Baseline was about 10 seconds.)

[MaxGraey]

Sounds like ccache but for AssemblyScript)

[dcodeIO]

One prerequisite here is that Node#range must be redesigned so it becomes serializable / remain valid between different programs, for example by replacing the source reference with a sourceIndex into a global sources array or similar. Has some implications on other parts of the compiler that currently use range without being aware of program context. Other than that I'm not yet sure how much improvement caching to disk will yield (in memory is fine), like deserialization from something like JSON vs text parsing might not make much of a difference, while a binary format might.

[MaxGraey]

instead JSON as serialization protocol we could use floatbuffer / protobuffer

[willemneal]

The way that I previously solved this was that main didn't throw away the parser between executions of main. The files that @jtenner references don't change their range values between different executions. I agree with @MaxGraey that we could just use a lower level serialization for now and not worry to much about performance, until we have an improved internal IR.