// This is the shared initialization code. It sets up the basic pointers,
// and allows enough extra space for a filler object. We call a virtual
// method, "lab_is_valid()" to handle the different asserts the old/young
// labs require. 
void PSPromotionLAB::initialize(MemRegion lab) {
  assert(lab_is_valid(lab), "Sanity");

  HeapWord* bottom = lab.start();
  HeapWord* end    = lab.end();

  set_bottom(bottom);
  set_end(end);
  set_top(bottom);

  // We can be initialized to a zero size!
  if (free() > 0) {
    if (ZapUnusedHeapArea) {
      debug_only(Memory::set_words(top(), free()/HeapWordSize, badHeapWord));
    }
    
    // NOTE! We need to allow space for a filler object.
    assert(lab.word_size() >= filler_header_size, "lab is too small");
    end = end - filler_header_size;
    set_end(end);

    _state = needs_flush;
  } else {
    _state = zero_size;
  }

  assert(this->top() <= this->end(), "pointers out of order");
}
Пример #2
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// This is the shared initialization code. It sets up the basic pointers,
// and allows enough extra space for a filler object. We call a virtual
// method, "lab_is_valid()" to handle the different asserts the old/young
// labs require.
void PSPromotionLAB::initialize(MemRegion lab) {
  assert(lab_is_valid(lab), "Sanity");

  HeapWord* bottom = lab.start();
  HeapWord* end    = lab.end();

  set_bottom(bottom);
  set_end(end);
  set_top(bottom);

  // Initialize after VM starts up because header_size depends on compressed
  // oops.
  filler_header_size = align_object_size(typeArrayOopDesc::header_size(T_INT));

  // We can be initialized to a zero size!
  if (free() > 0) {
    if (ZapUnusedHeapArea) {
      debug_only(Copy::fill_to_words(top(), free()/HeapWordSize, badHeapWord));
    }

    // NOTE! We need to allow space for a filler object.
    assert(lab.word_size() >= filler_header_size, "lab is too small");
    end = end - filler_header_size;
    set_end(end);

    _state = needs_flush;
  } else {
    _state = zero_size;
  }

  assert(this->top() <= this->end(), "pointers out of order");
}