spaces.cc.svn-base

Google浏览器V8内核代码

#endif

  start_ = NULL;
  capacity_ = 0;
  allocation_info_.top = NULL;
  allocation_info_.limit = NULL;
  mc_forwarding_info_.top = NULL;
  mc_forwarding_info_.limit = NULL;

  if (to_space_ != NULL) {
    to_space_->TearDown();
    delete to_space_;
    to_space_ = NULL;
  }

  if (from_space_ != NULL) {
    from_space_->TearDown();
    delete from_space_;
    from_space_ = NULL;
  }
}


void NewSpace::Flip() {
  SemiSpace* tmp = from_space_;
  from_space_ = to_space_;
  to_space_ = tmp;
}


bool NewSpace::Double() {
  ASSERT(capacity_ <= maximum_capacity_ / 2);
  // TODO(1240712): Failure to double the from space can result in
  // semispaces of different sizes.  In the event of that failure, the
  // to space doubling should be rolled back before returning false.
  if (!to_space_->Double() || !from_space_->Double()) return false;
  capacity_ *= 2;
  allocation_info_.limit = to_space_->high();
  ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
  return true;
}


void NewSpace::ResetAllocationInfo() {
  allocation_info_.top = to_space_->low();
  allocation_info_.limit = to_space_->high();
  ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
}


void NewSpace::MCResetRelocationInfo() {
  mc_forwarding_info_.top = from_space_->low();
  mc_forwarding_info_.limit = from_space_->high();
  ASSERT_SEMISPACE_ALLOCATION_INFO(mc_forwarding_info_, from_space_);
}


void NewSpace::MCCommitRelocationInfo() {
  // Assumes that the spaces have been flipped so that mc_forwarding_info_ is
  // valid allocation info for the to space.
  allocation_info_.top = mc_forwarding_info_.top;
  allocation_info_.limit = to_space_->high();
  ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
}


#ifdef DEBUG
// We do not use the SemispaceIterator because verification doesn't assume
// that it works (it depends on the invariants we are checking).
void NewSpace::Verify() {
  // The allocation pointer should be in the space or at the very end.
  ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);

  // There should be objects packed in from the low address up to the
  // allocation pointer.
  Address current = to_space_->low();
  while (current < top()) {
    HeapObject* object = HeapObject::FromAddress(current);

    // The first word should be a map, and we expect all map pointers to
    // be in map space.
    Map* map = object->map();
    ASSERT(map->IsMap());
    ASSERT(Heap::map_space()->Contains(map));

    // The object should not be code or a map.
    ASSERT(!object->IsMap());
    ASSERT(!object->IsCode());

    // The object itself should look OK.
    object->Verify();

    // All the interior pointers should be contained in the heap.
    VerifyPointersVisitor visitor;
    int size = object->Size();
    object->IterateBody(map->instance_type(), size, &visitor);

    current += size;
  }

  // The allocation pointer should not be in the middle of an object.
  ASSERT(current == top());
}
#endif


// -----------------------------------------------------------------------------
// SemiSpace implementation

SemiSpace::SemiSpace(int initial_capacity,
                     int maximum_capacity,
                     AllocationSpace id)
    : Space(id, NOT_EXECUTABLE), capacity_(initial_capacity),
      maximum_capacity_(maximum_capacity), start_(NULL), age_mark_(NULL) {
}


bool SemiSpace::Setup(Address start, int size) {
  ASSERT(size == maximum_capacity_);
  if (!MemoryAllocator::CommitBlock(start, capacity_, executable())) {
    return false;
  }

  start_ = start;
  address_mask_ = ~(size - 1);
  object_mask_ = address_mask_ | kHeapObjectTag;
  object_expected_ = reinterpret_cast<uint32_t>(start) | kHeapObjectTag;

  age_mark_ = start_;
  return true;
}


void SemiSpace::TearDown() {
  start_ = NULL;
  capacity_ = 0;
}


bool SemiSpace::Double() {
  if (!MemoryAllocator::CommitBlock(high(), capacity_, executable())) {
    return false;
  }
  capacity_ *= 2;
  return true;
}


#ifdef DEBUG
void SemiSpace::Print() { }


void SemiSpace::Verify() { }
#endif


// -----------------------------------------------------------------------------
// SemiSpaceIterator implementation.
SemiSpaceIterator::SemiSpaceIterator(NewSpace* space) {
  Initialize(space, space->bottom(), space->top(), NULL);
}


SemiSpaceIterator::SemiSpaceIterator(NewSpace* space,
                                     HeapObjectCallback size_func) {
  Initialize(space, space->bottom(), space->top(), size_func);
}


SemiSpaceIterator::SemiSpaceIterator(NewSpace* space, Address start) {
  Initialize(space, start, space->top(), NULL);
}


void SemiSpaceIterator::Initialize(NewSpace* space, Address start,
                                   Address end,
                                   HeapObjectCallback size_func) {
  ASSERT(space->ToSpaceContains(start));
  ASSERT(space->ToSpaceLow() <= end
         && end <= space->ToSpaceHigh());
  space_ = space->to_space_;
  current_ = start;
  limit_ = end;
  size_func_ = size_func;
}


#ifdef DEBUG
// A static array of histogram info for each type.
static HistogramInfo heap_histograms[LAST_TYPE+1];
static JSObject::SpillInformation js_spill_information;

// heap_histograms is shared, always clear it before using it.
static void ClearHistograms() {
  // We reset the name each time, though it hasn't changed.
#define DEF_TYPE_NAME(name) heap_histograms[name].set_name(#name);
  INSTANCE_TYPE_LIST(DEF_TYPE_NAME)
#undef DEF_TYPE_NAME

#define CLEAR_HISTOGRAM(name) heap_histograms[name].clear();
  INSTANCE_TYPE_LIST(CLEAR_HISTOGRAM)
#undef CLEAR_HISTOGRAM

  js_spill_information.Clear();
}


static int code_kind_statistics[Code::NUMBER_OF_KINDS];


static void ClearCodeKindStatistics() {
  for (int i = 0; i < Code::NUMBER_OF_KINDS; i++) {
    code_kind_statistics[i] = 0;
  }
}


static void ReportCodeKindStatistics() {
  const char* table[Code::NUMBER_OF_KINDS];

#define CASE(name)                            \
  case Code::name: table[Code::name] = #name; \
  break

  for (int i = 0; i < Code::NUMBER_OF_KINDS; i++) {
    switch (static_cast<Code::Kind>(i)) {
      CASE(FUNCTION);
      CASE(STUB);
      CASE(BUILTIN);
      CASE(LOAD_IC);
      CASE(KEYED_LOAD_IC);
      CASE(STORE_IC);
      CASE(KEYED_STORE_IC);
      CASE(CALL_IC);
    }
  }

#undef CASE

  PrintF("\n   Code kind histograms: \n");
  for (int i = 0; i < Code::NUMBER_OF_KINDS; i++) {
    if (code_kind_statistics[i] > 0) {
      PrintF("     %-20s: %10d bytes\n", table[i], code_kind_statistics[i]);
    }
  }
  PrintF("\n");
}


static int CollectHistogramInfo(HeapObject* obj) {
  InstanceType type = obj->map()->instance_type();
  ASSERT(0 <= type && type <= LAST_TYPE);
  ASSERT(heap_histograms[type].name() != NULL);
  heap_histograms[type].increment_number(1);
  heap_histograms[type].increment_bytes(obj->Size());

  if (FLAG_collect_heap_spill_statistics && obj->IsJSObject()) {
    JSObject::cast(obj)->IncrementSpillStatistics(&js_spill_information);
  }

  return obj->Size();
}


static void ReportHistogram(bool print_spill) {
  PrintF("\n  Object Histogram:\n");
  for (int i = 0; i <= LAST_TYPE; i++) {
    if (heap_histograms[i].number() > 0) {
      PrintF("    %-33s%10d (%10d bytes)\n",
             heap_histograms[i].name(),
             heap_histograms[i].number(),
             heap_histograms[i].bytes());
    }
  }
  PrintF("\n");

  // Summarize string types.
  int string_number = 0;
  int string_bytes = 0;
#define INCREMENT(type, size, name)                  \
    string_number += heap_histograms[type].number(); \
    string_bytes += heap_histograms[type].bytes();
  STRING_TYPE_LIST(INCREMENT)
#undef INCREMENT
  if (string_number > 0) {
    PrintF("    %-33s%10d (%10d bytes)\n\n", "STRING_TYPE", string_number,
           string_bytes);
  }

  if (FLAG_collect_heap_spill_statistics && print_spill) {
    js_spill_information.Print();
  }
}
#endif  // DEBUG


// Support for statistics gathering for --heap-stats and --log-gc.
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
void NewSpace::ClearHistograms() {
  for (int i = 0; i <= LAST_TYPE; i++) {
    allocated_histogram_[i].clear();
    promoted_histogram_[i].clear();
  }
}

// Because the copying collector does not touch garbage objects, we iterate
// the new space before a collection to get a histogram of allocated objects.
// This only happens (1) when compiled with DEBUG and the --heap-stats flag is
// set, or when compiled with ENABLE_LOGGING_AND_PROFILING and the --log-gc
// flag is set.
void NewSpace::CollectStatistics() {
  ClearHistograms();
  SemiSpaceIterator it(this);
  while (it.has_next()) RecordAllocation(it.next());
}


#ifdef ENABLE_LOGGING_AND_PROFILING
static void DoReportStatistics(HistogramInfo* info, const char* description) {
  LOG(HeapSampleBeginEvent("NewSpace", description));
  // Lump all the string types together.
  int string_number = 0;
  int string_bytes = 0;
#define INCREMENT(type, size, name)       \
    string_number += info[type].number(); \
    string_bytes += info[type].bytes();
  STRING_TYPE_LIST(INCREMENT)
#undef INCREMENT
  if (string_number > 0) {
    LOG(HeapSampleItemEvent("STRING_TYPE", string_number, string_bytes));
  }

  // Then do the other types.
  for (int i = FIRST_NONSTRING_TYPE; i <= LAST_TYPE; ++i) {
    if (info[i].number() > 0) {
      LOG(HeapSampleItemEvent(info[i].name(), info[i].number(),
                              info[i].bytes()));
    }
  }
  LOG(HeapSampleEndEvent("NewSpace", description));
}
#endif  // ENABLE_LOGGING_AND_PROFILING


void NewSpace::ReportStatistics() {
#ifdef DEBUG
  if (FLAG_heap_stats) {
    float pct = static_cast<float>(Available()) / Capacity();
    PrintF("  capacity: %d, available: %d, %%%d\n",
           Capacity(), Available(), static_cast<int>(pct*100));
    PrintF("\n  Object Histogram:\n");
    for (int i = 0; i <= LAST_TYPE; i++) {
      if (allocated_histogram_[i].number() > 0) {
        PrintF("    %-33s%10d (%10d bytes)\n",
               allocated_histogram_[i].name(),
               allocated_histogram_[i].number(),
               allocated_histogram_[i].bytes());
      }
    }
    PrintF("\n");
  }
#endif  // DEBUG

#ifdef ENABLE_LOGGING_AND_PROFILING
  if (FLAG_log_gc) {
    DoReportStatistics(allocated_histogram_, "allocated");
    DoReportStatistics(promoted_histogram_, "promoted");
  }
#endif  // ENABLE_LOGGING_AND_PROFILING
}


void NewSpace::RecordAllocation(HeapObject* obj) {
  InstanceType type = obj->map()->instance_type();
  ASSERT(0 <= type && type <= LAST_TYPE);
  allocated_histogram_[type].increment_number(1);
  allocated_histogram_[type].increment_bytes(obj->Size());
}


void NewSpace::RecordPromotion(HeapObject* obj) {
  InstanceType type = obj->map()->instance_type();
  ASSERT(0 <= type && type <= LAST_TYPE);
  promoted_histogram_[type].increment_number(1);
  promoted_histogram_[type].increment_bytes(obj->Size());
}
#endif  // defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)


// -----------------------------------------------------------------------------
// Free lists for old object spaces implementation

void FreeListNode::set_size(int size_in_bytes) {
  ASSERT(size_in_bytes > 0);
  ASSERT(IsAligned(size_in_bytes, kPointerSize));

  // We write a map and possibly size information to the block.  If the block
  // is big enough to be a ByteArray with at least one extra word (the next
  // pointer), we set its map to be the byte array map and its size to an
  // appropriate array length for the desired size from HeapObject::Size().
  // If the block is too small (eg, one or two words), to hold both a size
  // field and a next pointer, we give it a filler map that gives it the
  // correct size.
  if (size_in_bytes > Array::kHeaderSize) {
    set_map(Heap::byte_array_map());
    ByteArray::cast(this)->set_length(ByteArray::LengthFor(size_in_bytes));
  } else if (size_in_bytes == kPointerSize) {
    set_map(Heap::one_word_filler_map());
  } else if (size_in_bytes == 2 * kPointerSize) {
    set_map(Heap::two_word_filler_map());
  } else {
    UNREACHABLE();