factor/vm/full_collector.cpp

#include "master.hpp"

namespace factor {

struct full_policy {
  factor_vm* parent;
  tenured_space* tenured;

  explicit full_policy(factor_vm* parent)
      : parent(parent), tenured(parent->data->tenured) {}

  bool should_copy_p(object* untagged) {
    return !tenured->contains_p(untagged);
  }

  void promoted_object(object* obj) {
    tenured->state.set_marked_p((cell)obj, obj->size());
    parent->mark_stack.push_back((cell)obj);
  }

  void visited_object(object* obj) {
    if (!tenured->state.marked_p((cell)obj))
      promoted_object(obj);
  }
};

// After a sweep, invalidate any code heap roots which are not marked,
// so that if a block makes a tail call to a generic word, and the PIC
// compiler triggers a GC, and the caller block gets GCd as a result,
// the PIC code won't try to overwrite the call site
void factor_vm::update_code_roots_for_sweep() {
  mark_bits* state = &code->allocator->state;

  FACTOR_FOR_EACH(code_roots) {
    code_root* root = *iter;
    cell block = root->value & (~data_alignment - 1);
    if (root->valid && !state->marked_p(block))
      root->valid = false;
  }
}

void factor_vm::collect_mark_impl() {
  gc_workhorse<tenured_space, full_policy>
      workhorse(this, this->data->tenured, full_policy(this));
  slot_visitor<gc_workhorse<tenured_space, full_policy>>
      visitor(this, workhorse);

  mark_stack.clear();

  code->allocator->state.clear_mark_bits();
  data->tenured->state.clear_mark_bits();

  visitor.visit_all_roots();
  visitor.visit_context_code_blocks();
  visitor.visit_uninitialized_code_blocks();

  visitor.visit_mark_stack(&mark_stack);

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

void factor_vm::collect_sweep_impl() {
  gc_event* event = current_gc->event;

  if (event)
    event->reset_timer();
  data->tenured->sweep();
  if (event)
    event->ended_data_sweep();

  update_code_roots_for_sweep();

  if (event)
    event->reset_timer();
  code->sweep();
  if (event)
    event->ended_code_sweep();
}

void factor_vm::collect_full() {
  collect_mark_impl();
  collect_sweep_impl();

  if (data->low_memory_p()) {
    // Full GC did not free up enough memory. Grow the heap.
    set_current_gc_op(collect_growing_heap_op);
    collect_growing_heap(0);
  } else if (data->high_fragmentation_p()) {
    // Enough free memory, but it is not contiguous. Perform a
    // compaction.
    set_current_gc_op(collect_compact_op);
    collect_compact_impl();
  }

  code->flush_icache();
}

}