345 
346   BlockTree() : _root(nullptr) {}
347 
348   // Add a memory block to the tree. Its content will be overwritten.
349   void add_block(MetaWord* p, size_t word_size) {
350     DEBUG_ONLY(zap_range(p, word_size));
351     assert(word_size >= MinWordSize, "invalid block size " SIZE_FORMAT, word_size);
352     Node* n = new(p) Node(word_size);
353     if (_root == nullptr) {
354       _root = n;
355     } else {
356       insert(_root, n);
357     }
358     _counter.add(word_size);
359   }
360 
361   // Given a word_size, search and return the smallest block that is equal or
362   //  larger than that size. Upon return, *p_real_word_size contains the actual
363   //  block size.
364   MetaWord* remove_block(size_t word_size, size_t* p_real_word_size) {
365     assert(word_size >= MinWordSize, "invalid block size " SIZE_FORMAT, word_size);
366 
367     Node* n = find_closest_fit(word_size);
368 
369     if (n != nullptr) {
370       DEBUG_ONLY(check_node(n);)
371       assert(n->_word_size >= word_size, "sanity");
372 
373       if (n->_next != nullptr) {
374         // If the node is head of a chain of same sized nodes, we leave it alone
375         //  and instead remove one of the follow up nodes (which is simpler than
376         //  removing the chain head node and then having to graft the follow up
377         //  node into its place in the tree).
378         n = remove_from_list(n);
379       } else {
380         remove_node_from_tree(n);
381       }
382 
383       MetaWord* p = (MetaWord*)n;
384       *p_real_word_size = n->_word_size;
385 

345 
346   BlockTree() : _root(nullptr) {}
347 
348   // Add a memory block to the tree. Its content will be overwritten.
349   void add_block(MetaWord* p, size_t word_size) {
350     DEBUG_ONLY(zap_range(p, word_size));
351     assert(word_size >= MinWordSize, "invalid block size " SIZE_FORMAT, word_size);
352     Node* n = new(p) Node(word_size);
353     if (_root == nullptr) {
354       _root = n;
355     } else {
356       insert(_root, n);
357     }
358     _counter.add(word_size);
359   }
360 
361   // Given a word_size, search and return the smallest block that is equal or
362   //  larger than that size. Upon return, *p_real_word_size contains the actual
363   //  block size.
364   MetaWord* remove_block(size_t word_size, size_t* p_real_word_size) {
365     assert(word_size > 0, "invalid block size " SIZE_FORMAT, word_size);
366 
367     Node* n = find_closest_fit(word_size);
368 
369     if (n != nullptr) {
370       DEBUG_ONLY(check_node(n);)
371       assert(n->_word_size >= word_size, "sanity");
372 
373       if (n->_next != nullptr) {
374         // If the node is head of a chain of same sized nodes, we leave it alone
375         //  and instead remove one of the follow up nodes (which is simpler than
376         //  removing the chain head node and then having to graft the follow up
377         //  node into its place in the tree).
378         n = remove_from_list(n);
379       } else {
380         remove_node_from_tree(n);
381       }
382 
383       MetaWord* p = (MetaWord*)n;
384       *p_real_word_size = n->_word_size;
385