whatever I do, things get slower and bigger

[Bill Baxter]

BCS wrote:
> I'm working on my parser generator and trying to shoe horn it into a 
> smaller memory foot print. One approach I'm trying, is to replace 
> recursive templates with CTFE function and string mixins. This is in an 
> effort to reduce the number of types that get declared (mostly I'm using 
> struct templates). The problem is that the CTFE functions seem to 
> actually use MORE ram than the templates do. I've tried a number of 
> things like converting to an O(n log n) concatenation system rather than 
> a O(n^2) and other such tricks but everything seems to be going 
> backwards. Any advice? (D v1 BTW) I can post code if anyone cares (it's 
> kind of large: 1.2KLOC, takes a while to compile: ~6min, and use a lot 
> of RAM: ~2GB).
> 
> (after a bit more fiddling)
> 
> I've got it down to 1GB of ram (Yeah!). My conclusions: don't build 
> strings with CTFE unless it's a lot harder to do it with templates. It 
> seems that CTFE is a bigger memory hog than templates even with temples 
> memoizing everything into the symbol tables.
> 
> 

Yes I believe Don has previously reported that CTFE manipulations on 
strings basically *never* free the intermediate strings.  Basically the 
CTFE engine needs a garbage collector (or equiv).

--bb