1 /* 2 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "gc/g1/g1CardTable.hpp" 27 #include "gc/g1/g1CollectedHeap.inline.hpp" 28 #include "gc/shared/memset_with_concurrent_readers.hpp" 29 #include "logging/log.hpp" 30 #include "runtime/atomic.hpp" 31 #include "runtime/orderAccess.inline.hpp" 32 33 bool G1CardTable::mark_card_deferred(size_t card_index) { 34 jbyte val = _byte_map[card_index]; 35 // It's already processed 36 if ((val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val()) { 37 return false; 38 } 39 40 // Cached bit can be installed either on a clean card or on a claimed card. 41 jbyte new_val = val; 42 if (val == clean_card_val()) { 43 new_val = (jbyte)deferred_card_val(); 44 } else { 45 if (val & claimed_card_val()) { 46 new_val = val | (jbyte)deferred_card_val(); 47 } 48 } 49 if (new_val != val) { 50 Atomic::cmpxchg(new_val, &_byte_map[card_index], val); 51 } 52 return true; 53 } 54 55 void G1CardTable::g1_mark_as_young(const MemRegion& mr) { 56 jbyte *const first = byte_for(mr.start()); 57 jbyte *const last = byte_after(mr.last()); 58 59 memset_with_concurrent_readers(first, g1_young_gen, last - first); 60 } 61 62 #ifndef PRODUCT 63 void G1CardTable::verify_g1_young_region(MemRegion mr) { 64 verify_region(mr, g1_young_gen, true); 65 } 66 #endif 67 68 void G1CardTableChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) { 69 // Default value for a clean card on the card table is -1. So we cannot take advantage of the zero_filled parameter. 70 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords); 71 _card_table->clear(mr); 72 } 73 74 void G1CardTable::initialize(G1RegionToSpaceMapper* mapper) { 75 mapper->set_mapping_changed_listener(&_listener); 76 77 _byte_map_size = mapper->reserved().byte_size(); 78 79 _guard_index = cards_required(_whole_heap.word_size()) - 1; 80 _last_valid_index = _guard_index - 1; 81 82 HeapWord* low_bound = _whole_heap.start(); 83 HeapWord* high_bound = _whole_heap.end(); 84 85 _cur_covered_regions = 1; 86 _covered[0] = _whole_heap; 87 88 _byte_map = (jbyte*) mapper->reserved().start(); 89 _byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift); 90 assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map"); 91 assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map"); 92 93 log_trace(gc, barrier)("G1CardTable::G1CardTable: "); 94 log_trace(gc, barrier)(" &_byte_map[0]: " INTPTR_FORMAT " &_byte_map[_last_valid_index]: " INTPTR_FORMAT, 95 p2i(&_byte_map[0]), p2i(&_byte_map[_last_valid_index])); 96 log_trace(gc, barrier)(" _byte_map_base: " INTPTR_FORMAT, p2i(_byte_map_base)); 97 } 98 99 bool G1CardTable::is_in_young(void* addr) const { 100 jbyte* p = byte_for(addr); 101 return *p == G1CardTable::g1_young_card_val(); 102 }