1 /* 2 * Copyright (c) 2016, 2020, 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 #ifndef SHARE_GC_SHARED_PRESERVEDMARKS_HPP 26 #define SHARE_GC_SHARED_PRESERVEDMARKS_HPP 27 28 #include "memory/allocation.hpp" 29 #include "memory/padded.hpp" 30 #include "oops/oop.hpp" 31 #include "utilities/stack.hpp" 32 33 class AbstractGangTask; 34 class PreservedMarksSet; 35 class WorkGang; 36 37 class PreservedMarks { 38 private: 39 class OopAndMarkWord { 40 private: 41 oop _o; 42 markWord _m; 43 44 public: 45 OopAndMarkWord(oop obj, markWord m) : _o(obj), _m(m) { } 46 47 oop get_oop() { return _o; } 48 inline void set_mark() const; 49 void set_oop(oop obj) { _o = obj; } 50 }; 51 typedef Stack<OopAndMarkWord, mtGC> OopAndMarkWordStack; 52 53 OopAndMarkWordStack _stack; 54 55 inline bool should_preserve_mark(oop obj, markWord m) const; 56 57 template <bool ALT_FWD> 58 void adjust_during_full_gc_impl(); 59 60 public: 61 size_t size() const { return _stack.size(); } 62 inline void push(oop obj, markWord m); 63 inline void push_if_necessary(oop obj, markWord m); 64 // Iterate over the stack, restore all preserved marks, and 65 // reclaim the memory taken up by the stack segments. 66 void restore(); 67 // Iterate over the stack, adjust all preserved marks according 68 // to their forwarding location stored in the mark. 69 void adjust_during_full_gc(); 70 71 void restore_and_increment(volatile size_t* const _total_size_addr); 72 inline static void init_forwarded_mark(oop obj); 73 74 // Assert the stack is empty and has no cached segments. 75 void assert_empty() PRODUCT_RETURN; 76 77 inline PreservedMarks(); 78 ~PreservedMarks() { assert_empty(); } 79 }; 80 81 class RemoveForwardedPointerClosure: public ObjectClosure { 82 public: 83 virtual void do_object(oop obj); 84 }; 85 86 class PreservedMarksSet : public CHeapObj<mtGC> { 87 private: 88 // true -> _stacks will be allocated in the C heap 89 // false -> _stacks will be allocated in the resource arena 90 const bool _in_c_heap; 91 92 // Number of stacks we have allocated (typically, one stack per GC worker). 93 // This should be >= 1 if the stacks have been initialized, 94 // or == 0 if they have not. 95 uint _num; 96 97 // Stack array (typically, one stack per GC worker) of length _num. 98 // This should be != NULL if the stacks have been initialized, 99 // or == NULL if they have not. 100 Padded<PreservedMarks>* _stacks; 101 102 public: 103 uint num() const { return _num; } 104 105 // Return the i'th stack. 106 PreservedMarks* get(uint i = 0) const { 107 assert(_num > 0 && _stacks != NULL, "stacks should have been initialized"); 108 assert(i < _num, "pre-condition"); 109 return (_stacks + i); 110 } 111 112 // Allocate stack array. 113 void init(uint num); 114 115 // Iterate over all stacks, restore all preserved marks, and reclaim 116 // the memory taken up by the stack segments using the given WorkGang. If the WorkGang 117 // is NULL, perform the work serially in the current thread. 118 void restore(WorkGang* workers); 119 120 AbstractGangTask* create_task(); 121 122 // Reclaim stack array. 123 void reclaim(); 124 125 // Assert all the stacks are empty and have no cached segments. 126 void assert_empty() PRODUCT_RETURN; 127 128 PreservedMarksSet(bool in_c_heap) 129 : _in_c_heap(in_c_heap), _num(0), _stacks(NULL) { } 130 131 ~PreservedMarksSet() { 132 assert(_stacks == NULL && _num == 0, "stacks should have been reclaimed"); 133 } 134 }; 135 136 #endif // SHARE_GC_SHARED_PRESERVEDMARKS_HPP