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   object_start_offsets = new card[addr_to_card(size)];
   8   object_start_offsets_end = object_start_offsets + addr_to_card(size);
   9   clear_object_start_offsets();
  10 }
  11
  12 object_start_map::~object_start_map() { delete[] object_start_offsets; }
  13
  14 cell object_start_map::first_object_in_card(cell card_index) {
  15   return object_start_offsets[card_index];
  16 }
  17
  18 cell object_start_map::find_object_containing_card(cell card_index) {
  19   if (card_index == 0)
  20     return start;
  21   else {
  22     card_index--;
  23
  24     while (first_object_in_card(card_index) == card_starts_inside_object) {
  25       /* First card should start with an object */
  26       FACTOR_ASSERT(card_index > 0);
  27       card_index--;
  28     }
  29
  30     return start + (card_index << card_bits) + first_object_in_card(card_index);
  31   }
  32 }
  33
  34 /* we need to remember the first object allocated in the card */
  35 void object_start_map::record_object_start_offset(object* obj) {
  36   cell idx = addr_to_card((cell) obj - start);
  37   card obj_start = ((cell) obj & addr_card_mask);
  38   object_start_offsets[idx] = std::min(object_start_offsets[idx], obj_start);
  39 }
  40
  41 void object_start_map::clear_object_start_offsets() {
  42   memset(object_start_offsets, card_starts_inside_object, addr_to_card(size));
  43 }
  44
  45 void object_start_map::update_card_for_sweep(cell index, u16 mask) {
  46   cell offset = object_start_offsets[index];
  47   if (offset != card_starts_inside_object) {
  48     mask >>= (offset / data_alignment);
  49
  50     if (mask == 0) {
  51       /* The rest of the block after the old object start is free */
  52       object_start_offsets[index] = card_starts_inside_object;
  53     } else {
  54       /* Move the object start forward if necessary */
  55       object_start_offsets[index] =
  56           (card)(offset + (rightmost_set_bit(mask) * data_alignment));
  57     }
  58   }
  59 }
  60
  61 void object_start_map::update_for_sweep(mark_bits<object>* state) {
  62   for (cell index = 0; index < state->bits_size; index++) {
  63     cell mask = state->marked[index];
  64 #ifdef FACTOR_64
  65     update_card_for_sweep(index * 4, mask & 0xffff);
  66     update_card_for_sweep(index * 4 + 1, (mask >> 16) & 0xffff);
  67     update_card_for_sweep(index * 4 + 2, (mask >> 32) & 0xffff);
  68     update_card_for_sweep(index * 4 + 3, (mask >> 48) & 0xffff);
  69 #else
  70     update_card_for_sweep(index * 2, mask & 0xffff);
  71     update_card_for_sweep(index * 2 + 1, (mask >> 16) & 0xffff);
  72 #endif
  73   }
  74 }
  75
  76 }