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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.
*
*/
#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;
}
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