factor/vm/aging_collector.cpp

#include "master.hpp"

namespace factor {

struct to_aging_copier : no_fixup {
  aging_space* aging;
  tenured_space* tenured;

  to_aging_copier(aging_space* aging, tenured_space* tenured)
      : aging(aging), tenured(tenured) { }

  object* fixup_data(object* obj) {
    if (aging->contains_p(obj) || tenured->contains_p(obj)) {
      return obj;
    }

    // Is there another forwarding pointer?
    while (obj->forwarding_pointer_p()) {
      object* dest = obj->forwarding_pointer();
      obj = dest;
    }

    if (aging->contains_p(obj) || tenured->contains_p(obj)) {
      return obj;
    }

    cell size = obj->size();
    object* newpointer = aging->allot(size);
    if (!newpointer)
      throw must_start_gc_again();

    memcpy(newpointer, obj, size);
    obj->forward_to(newpointer);

    return newpointer;
  }
};

void factor_vm::collect_aging() {
  // Promote objects referenced from tenured space to tenured space, copy
  // everything else to the aging semi-space, and reset the nursery pointer.
  {
    // Change the op so that if we fail here, an assertion will be raised.
    current_gc->op = collect_to_tenured_op;

    slot_visitor<from_tenured_refs_copier>
        visitor(this, from_tenured_refs_copier(data->tenured, &mark_stack));

    gc_event* event = current_gc->event;

    if (event)
      event->reset_timer();
    visitor.visit_cards(data->tenured, card_points_to_aging, 0xff);
    if (event)
      event->ended_card_scan(visitor.cards_scanned, visitor.decks_scanned);

    if (event)
      event->reset_timer();
    visitor.visit_code_heap_roots(&code->points_to_aging);
    if (event)
      event->ended_code_scan(code->points_to_aging.size());

    visitor.visit_mark_stack(&mark_stack);
  }
  {
    // If collection fails here, do a to_tenured collection.
    current_gc->op = collect_aging_op;

    std::swap(data->aging, data->aging_semispace);
    data->reset_aging();

    aging_space *aging = data->aging;
    slot_visitor<to_aging_copier>
        visitor(this, to_aging_copier(aging, data->tenured));

    cell scan = aging->start + aging->occupied_space();

    visitor.visit_all_roots();
    visitor.cheneys_algorithm(aging, scan);

    data->reset_nursery();
    code->clear_remembered_set();
  }
}

}