Comment by moonchild
5 years ago
For a basic GC, code generation should be unaffected. The only place you'd need to care about code generation is if you wanted to make a realtime GC, inserting read or write barriers.
5 years ago
For a basic GC, code generation should be unaffected. The only place you'd need to care about code generation is if you wanted to make a realtime GC, inserting read or write barriers.
My understanding from doing a bit of reading is that there are at least two things codegen-adjacent that an accurate collector will want (even if you stop the world while collecting):
1. The locations of pointers inside of allocations.
2. The locations of pointers in the stack (into which you may need to spill registers).
I can think of ways to do these (e.g. perhaps each stack frame contains a bitmask at a certain offset), but I'd love to learn what the best practices are.
Usually your objects are boxed, and the box contains a type identifier which the gc can use to identify pointer offsets. It is apparently possible to do precise garbage collection without boxes—I'll see if I can find the paper and link it later—but this is not widely done.