They just use the implementation from the last version of the compiler, which you can follow back in a long chain to the first implementation. As for the implem

They just use the implementation from the last version of the compiler, which you can follow back in a long chain to the first implementation. As for the implementation of the garbage collector, it probably just doesn't allocate anything. The basics of a garbage collector are a function "alloc" and another one "collect". The function to allocate memory usually looks something like this: char heap[100000000]; int heap_end; void *alloc(int n_bytes) { void *out = &heap[heap_end] heap_end += n_bytes; return out; } As you can see, it doesn't need to allocate any memory to do this.