Official compiler

[David Nadlinger via Digitalmars-d]

On Friday, 26 February 2016 at 18:53:21 UTC, Andrei Alexandrescu 
wrote:
> My understanding is the main problem is the _same_ templates 
> are repeatedly instantiated with the same exact parameters - 
> the epitome of redundant work. -- Andrei

Within one compiler execution, there might be some optimization 
potential in the way semantically equivalent template 
instantiations are merged, yes – it's been a while since I have 
looked at the related code (see e.g. 
TemplateDeclaration.findExistingInstance).

Another area matching your description would be that of the same 
template being instantiated from multiple compilation units, 
where it can be omitted from some of the compilation units (i.e. 
object files). Our current logic for that is broken anyway, see 
e.g. https://issues.dlang.org/show_bug.cgi?id=15318.

I was referring to something different in my post, though, as the 
question concerned "low-hanging fruit". The problem there is 
really just that template names sometimes grow unreasonably long 
pretty quickly. As an example, without wanting to divulge any 
internals, some of the mangled symbols (!) in the Weka codebase 
are several hundred kilobytes in size. core.demangle gives up on 
them anyway, and they appear to be extremely repetitive. Note 
that just like in Steven's post which I linked earlier, the code 
in question does not involve any crazy recursive meta-templates, 
but IIRC makes use of Voldemort types. Tracking down and fixing 
this – one would almost be tempted to just use standard data 
compression – would lead to a noticeable decrease in compile and 
link times for affected code.

  — David