Ref counting for CTFE?

[Dicebot via Digitalmars-d]

On Thursday, 29 May 2014 at 15:22:54 UTC, Steven Schveighoffer 
wrote:
> One subject that frequented the talks at dconf was the poor 
> performance of CTFE and mixins.
>
> The major issue as I understand it (maybe I'm wrong) is the 
> vast amounts of memory the compiler consumes while building 
> mixin strings. In fact, one of the talks (can't remember which 
> one) mentioned that someone had to build their project in steps 
> so the compiler did not crash from OOM.

It was during my talk. I have mentioned experience of Etienne 
(etcimon) when building ASN.1 parser using Pegged which was 
impossible to compile unless you did all code generation in 
separate run from actual project compilation.

I have talked about it with Don and he says that many CTFE memory 
allocation issues can be fixed without any GC by simply improving 
interpreter implementation. For example, incrementing an integer 
allocates new instance right now AFAIR. But he is very unlikely 
to work on it personally in any near future.

> As a side note, I find it weird that the compiler has given up 
> freeing memory, EVER, in order to achieve speed. Sure, the 
> killing of the process will act as the ultimate GC, but when it 
> is killed before the process is done compiling, the time it 
> takes to compile approaches infinity. And when the computer 
> helpfully starts swapping to avoid killing the process, things 
> aren't much better.

I'd love to see command-line flag that enables garbage collection 
in compiler (disabled by default). It does not matter how fast 
compiler is if it crashes on big project. And difference between 
10 seconds vs 30 seconds is not as important as difference 
between 2 seconds vs 10 seconds anyway.