Thread: Writing an interpreter (for a GC language) in C

How can one write an interpreter for a GC (garbage collected) language in C? I have tried the Boehm GC library, but the supplied Makefiles do not work and the documentation is horrid and out of date. Also I have heard that it fails to collect all garbage, thus leaking memory, which is unacceptable.

I would rather code the whole thing in standard C, and not rely on a 3rd party library. I don't want to write a platform-specific GC, using assembly code to implement.

I currently have a prototype implementation in Java, and the only thing preventing me from porting to C (for a great gain of efficiency) is the GC aspect.

I wish hardware had native support for memory GC at least. Now, I can *maybe* implement a GC since I know the root set of variables in the interpreter, but there are additional data structures like environments that ALSO need to be GC'd. Basically everything (user-visible objects and implementation objects) lives on the heap and need to be GC'd.

I have read that it is impossible to develop a GC library for C in general, but that it IS possible for a subset of C programs, where certain constructs are avoided throughout the code-base (things like pointer aliasing, ect). Does anyone know of such a GC library (that I can link in) and the exact restrictions of this?

If you're implementing your own language, it makes sense to implement your own GC as well. The GC doesn't necessarily need to apply to the C program itself. Only to the interpreted language program. In the interpretation process, you'll have full access to all of the stack frames, and as such, you'll be able to conclusively know whenever something is no longer referenced. Then it's a simple matter to collect the garbage, using a linked list of all allocations.