vm/object_start_map.cpp

   1 #include "master.hpp"
   2
   3 namespace factor {
   4
   5 object_start_map::object_start_map(cell size, cell start)
   6     : size(size), start(start) {
   7   cell card_count = size / card_size;
   8   object_start_offsets = new card[card_count];
   9   object_start_offsets_end = object_start_offsets + card_count;
  10   clear_object_start_offsets();
  11 }
  12
  13 object_start_map::~object_start_map() { delete[] object_start_offsets; }
  14
  15 cell object_start_map::find_object_containing_card(cell card_index) {
  16   if (card_index == 0)
  17     return start;
  18   else {
  19     card_index--;
  20
  21     while (object_start_offsets[card_index] == card_starts_inside_object) {
  22       /* First card should start with an object */
  23       FACTOR_ASSERT(card_index > 0);
  24       card_index--;
  25     }
  26     return start + card_index * card_size + object_start_offsets[card_index];
  27   }
  28 }
  29
  30 /* we need to remember the first object allocated in the card */
  31 void object_start_map::record_object_start_offset(object* obj) {
  32   cell idx = addr_to_card((cell)obj - start);
  33   card obj_start = ((cell)obj & addr_card_mask);
  34   object_start_offsets[idx] = std::min(object_start_offsets[idx], obj_start);
  35 }
  36
  37 void object_start_map::clear_object_start_offsets() {
  38   memset(object_start_offsets, card_starts_inside_object, addr_to_card(size));
  39 }
  40
  41 void object_start_map::update_card_for_sweep(cell index, uint16_t mask) {
  42   cell offset = object_start_offsets[index];
  43   if (offset != card_starts_inside_object) {
  44     mask >>= (offset / data_alignment);
  45
  46     if (mask == 0) {
  47       /* The rest of the block after the old object start is free */
  48       object_start_offsets[index] = card_starts_inside_object;
  49     } else {
  50       /* Move the object start forward if necessary */
  51       object_start_offsets[index] =
  52           (card)(offset + (rightmost_set_bit(mask) * data_alignment));
  53     }
  54   }
  55 }
  56
  57 void object_start_map::update_for_sweep(mark_bits* state) {
  58   for (cell index = 0; index < state->bits_size; index++) {
  59     cell mask = state->marked[index];
  60 #ifdef FACTOR_64
  61     update_card_for_sweep(index * 4, mask & 0xffff);
  62     update_card_for_sweep(index * 4 + 1, (mask >> 16) & 0xffff);
  63     update_card_for_sweep(index * 4 + 2, (mask >> 32) & 0xffff);
  64     update_card_for_sweep(index * 4 + 3, (mask >> 48) & 0xffff);
  65 #else
  66     update_card_for_sweep(index * 2, mask & 0xffff);
  67     update_card_for_sweep(index * 2 + 1, (mask >> 16) & 0xffff);
  68 #endif
  69   }
  70 }
  71
  72 }