Wed, 22 Aug 2001 09:17:31 -0700 (PDT)
> > I'm thinking of trying a simple re-write of the GC just to
> > see what I can get from low level tweaks. For more serious stuff on the GC,
> > it would be great if there were a bit in the header of objects that would
> > tell me if it was mutable or not.
> This should be easy enough to add.
If we're going to tweak the object headers, it might be worth stealing one
or two bits for alignment hints (i.e., getting doubles to be mod 8
> > This could be used in two distinct ways.
> > One would be for the generational GC, which needs to know about mutable
> > objects. The other would be to implement something that I had in
> > Mathematica: the `share' function. When you call it on a data object, it
> > returns a copy of that object which maximizes sharing. In Mathematica, you
> > could also call it on no arguments, which meant do this to the entire heap.
> > This was great for saving space at judicious moments. (In Mathematica,
> > although a real piece of junk, all the heap was immutable.)
> share sounds cool. I wonder how much it would buy in the compiler itself.
Maybe my coffee just hasn't kicked in yet, but how does `share' work?
Some kind of common-subobject-elimination? It just seems that the
equality test would be prohibitively expensive.