I have switched hxcpp over from using ref-counting to using Boehm garbage collection. I have also added some additional perfromance improvements, such as integer-index field names to make interaction with neko more efficient.
The overall result is that for the Physaxe demo, the frame rate went from 24 fps to 82 fps (in opengl mode). The swf file runs at about 35 fps, and neko at about 8 fps. This is about what I was hoping for from the first round, but I got there in the end.
You can download the updated files here.
I’m trying to get a speedup for the cpp backend for haxe by using garbage collection. Initial results are very promising – potentially about twice as fast. Howerver I spent a good few hours getting the the bottom of a little problem. Boehm garbage collection is a very impressive piece of work – it has all sorts of magic that does magical things, such as deal with virtual inheritance. This was a bit of a surprise because you do not always get “real” pointers, when you store an object pointer, you get one with an offset. However it seemed to work. Until I added finalizers to the external draw objectes used by the renderer. Apparently, you can only add finalizers to the “real” pointers (ie, those returned from “GC\_MALLOC” et al), rather than a pointer to the same object related by virtual inheritance. The symptom was that the object gets finalized in the first “gc_collect”, even though it was still “used” as far as I was concerned. I guess this is not too surpising, and the fix was pretty easy, but the fact that everything else worked so well lulled be into not suspecting this initially.