[m-rev.] for review: Cache transitive foreign imports.

[Zoltan Somogyi]

2022-11-24 14:45 GMT+11:00 "Peter Wang" <novalazy at gmail.com>:
> We previously cached the foreign imports of a module.
> find_module_foreign_imports always needs to compute the transitive
> foreign imports (i.e. including the foreign imports of transitively
> implementation-imported modules), so it had to take the union of a bunch
> of sets after looking up cached results.
> 
> This change caches the transitive foreign imports of a module, avoiding
> the bitset union operations, many/most of which turn out to be redundant.
> It reduces the average run time for a do-nothing build of Prince on my
> machine from 5.9 s to 3.1 s, for a speed up of ~47%.

That's great. Did you profile it to see whether there are any
obvious remaining bottlenecks?

> compiler/make.dependencies.m:
>     Cache transitive foreign module imports instead of direct foreign
>     module imports.
> 
>     Delete code to make use va_map; it is no longer used.

Some word is missing there.

The diff itself is fine.

Zoltan.