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 /*

  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

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  */

 #include "precompiled.hpp"

 #include "gc_implementation/parallelScavenge/objectStartArray.hpp"

 #include "memory/allocation.inline.hpp"

 #include "memory/cardTableModRefBS.hpp"

 #include "oops/oop.inline.hpp"

 #include "runtime/java.hpp"

 void ObjectStartArray::initialize(MemRegion reserved_region) {

   // We're based on the assumption that we use the same

   // size blocks as the card table.

   assert((int)block_size == (int)CardTableModRefBS::card_size, "Sanity");

   assert((int)block_size <= 512, "block_size must be less than or equal to 512");

   // Calculate how much space must be reserved

   _reserved_region = reserved_region;

   size_t bytes_to_reserve = reserved_region.word_size() / block_size_in_words;

   assert(bytes_to_reserve > 0, "Sanity");

   bytes_to_reserve =

     align_size_up(bytes_to_reserve, os::vm_allocation_granularity());

   // Do not use large-pages for the backing store. The one large page region

   // will be used for the heap proper.

   ReservedSpace backing_store(bytes_to_reserve);

   if (!backing_store.is_reserved()) {

     vm_exit_during_initialization("Could not reserve space for ObjectStartArray");

   }

   // We do not commit any memory initially

   if (!_virtual_space.initialize(backing_store, 0)) {

     vm_exit_during_initialization("Could not commit space for ObjectStartArray");

   }

   _raw_base = (jbyte*)_virtual_space.low_boundary();

   if (_raw_base == NULL) {

     vm_exit_during_initialization("Could not get raw_base address");

   }

   _offset_base = _raw_base - (size_t(reserved_region.start()) >> block_shift);

   _covered_region.set_start(reserved_region.start());

   _covered_region.set_word_size(0);

   _blocks_region.set_start((HeapWord*)_raw_base);

   _blocks_region.set_word_size(0);

 }

 void ObjectStartArray::set_covered_region(MemRegion mr) {

   assert(_reserved_region.contains(mr), "MemRegion outside of reserved space");

   assert(_reserved_region.start() == mr.start(), "Attempt to move covered region");

   HeapWord* low_bound  = mr.start();

   HeapWord* high_bound = mr.end();

   assert((uintptr_t(low_bound)  & (block_size - 1))  == 0, "heap must start at block boundary");

   assert((uintptr_t(high_bound) & (block_size - 1))  == 0, "heap must end at block boundary");

   size_t requested_blocks_size_in_bytes = mr.word_size() / block_size_in_words;

   // Only commit memory in page sized chunks

   requested_blocks_size_in_bytes =

     align_size_up(requested_blocks_size_in_bytes, os::vm_page_size());

   _covered_region = mr;

   size_t current_blocks_size_in_bytes = _blocks_region.byte_size();

   if (requested_blocks_size_in_bytes > current_blocks_size_in_bytes) {

     // Expand

     size_t expand_by = requested_blocks_size_in_bytes - current_blocks_size_in_bytes;

     if (!_virtual_space.expand_by(expand_by)) {

       vm_exit_out_of_memory(expand_by, "object start array expansion");

     }

     // Clear *only* the newly allocated region

     memset(_blocks_region.end(), clean_block, expand_by);

   }

   if (requested_blocks_size_in_bytes < current_blocks_size_in_bytes) {

     // Shrink

     size_t shrink_by = current_blocks_size_in_bytes - requested_blocks_size_in_bytes;

     _virtual_space.shrink_by(shrink_by);

   }

   _blocks_region.set_word_size(requested_blocks_size_in_bytes / sizeof(HeapWord));

   assert(requested_blocks_size_in_bytes % sizeof(HeapWord) == 0, "Block table not expanded in word sized increment");

   assert(requested_blocks_size_in_bytes == _blocks_region.byte_size(), "Sanity");

   assert(block_for_addr(low_bound) == &_raw_base[0], "Checking start of map");

   assert(block_for_addr(high_bound-1) <= &_raw_base[_blocks_region.byte_size()-1], "Checking end of map");

 }

 void ObjectStartArray::reset() {

   memset(_blocks_region.start(), clean_block, _blocks_region.byte_size());

 }

 bool ObjectStartArray::object_starts_in_range(HeapWord* start_addr,

                                               HeapWord* end_addr) const {

   assert(start_addr <= end_addr, "range is wrong");

   if (start_addr > end_addr) {

     return false;

   }

   jbyte* start_block = block_for_addr(start_addr);

   jbyte* end_block = block_for_addr(end_addr);

   for (jbyte* block = start_block; block <= end_block; block++) {

     if (*block != clean_block) {

       return true;

     }

   }

   // No object starts in this slice; verify this using

   // more traditional methods:

   assert(object_start(end_addr - 1) <= start_addr,

          "Oops an object does start in this slice?");

   return false;

 }