On 08/03/2009, at 12:45 PM, Austin Seipp wrote:
For garbage collection, please see.
"Accurate Garbage Collection in an Uncooperative Environment" - http://citeseer.ist.psu.edu/538613.html
This strategy is currently used in Mercury as well as Ben L.'s DDC language; on that note, I think if you spent some time looking through the runtime/generated code of DDC, you can see exactly what the paper is talking about, because it's actually a very simple strategy for holding onto GC roots:
That paper explains the basic idea, but neither DDC or Mercury quite follow it (I asked Zoltan). The system in the paper keeps the GC roots in structs on the C stack, and chains the structs together as a linked list. The problem is that if you take a pointer to data on the C stack then GCC freaks out and disables a host of optimisations. I imagine it's worried about pointers going bad after the stack frame is popped and the space for the struct gets lost. DDC keeps a shadow stack of GC roots in malloced memory. It's only a small difference, but lets the C compiler produce better code. Ben.