1 /* 2 * Copyright (c) 2000, 2018, 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_VM_MEMORY_MEMREGION_HPP 26 #define SHARE_VM_MEMORY_MEMREGION_HPP 27 28 #include "memory/allocation.hpp" 29 #include "utilities/debug.hpp" 30 #include "utilities/globalDefinitions.hpp" 31 32 // A very simple data structure representing a contigous region 33 // region of address space. 34 35 // Note that MemRegions are passed by value, not by reference. 36 // The intent is that they remain very small and contain no 37 // objects. These should never be allocated in heap but we do 38 // create MemRegions (in CardTableModRefBS) in heap so operator 39 // new and operator new [] added for this special case. 40 41 class MetaWord; 42 43 class MemRegion { 44 friend class VMStructs; 45 private: 46 HeapWord* _start; 47 size_t _word_size; 48 49 public: 50 MemRegion() : _start(NULL), _word_size(0) {}; 51 MemRegion(HeapWord* start, size_t word_size) : 52 _start(start), _word_size(word_size) {}; 53 MemRegion(HeapWord* start, HeapWord* end) : 54 _start(start), _word_size(pointer_delta(end, start)) { 55 assert(end >= start, "incorrect constructor arguments"); 56 } 57 MemRegion(MetaWord* start, MetaWord* end) : 58 _start((HeapWord*)start), _word_size(pointer_delta(end, start)) { 59 assert(end >= start, "incorrect constructor arguments"); 60 } 61 62 MemRegion(const MemRegion& mr): _start(mr._start), _word_size(mr._word_size) {} 63 64 MemRegion intersection(const MemRegion mr2) const; 65 // regions must overlap or be adjacent 66 MemRegion _union(const MemRegion mr2) const; 67 // minus will fail a guarantee if mr2 is interior to this, 68 // since there's no way to return 2 disjoint regions. 69 MemRegion minus(const MemRegion mr2) const; 70 71 HeapWord* start() const { return _start; } 72 HeapWord* end() const { return _start + _word_size; } 73 HeapWord* last() const { return _start + _word_size - 1; } 74 75 void set_start(HeapWord* start) { _start = start; } 76 void set_end(HeapWord* end) { _word_size = pointer_delta(end, _start); } 77 void set_word_size(size_t word_size) { 78 _word_size = word_size; 79 } 80 81 bool contains(const MemRegion mr2) const { 82 return _start <= mr2._start && end() >= mr2.end(); 83 } 84 bool contains(const void* addr) const { 85 return addr >= (void*)_start && addr < (void*)end(); 86 } 87 bool equals(const MemRegion mr2) const { 88 // first disjunct since we do not have a canonical empty set 89 return ((is_empty() && mr2.is_empty()) || 90 (start() == mr2.start() && end() == mr2.end())); 91 } 92 93 size_t byte_size() const { return _word_size * sizeof(HeapWord); } 94 size_t word_size() const { return _word_size; } 95 96 bool is_empty() const { return word_size() == 0; } 97 void* operator new(size_t size) throw(); 98 void* operator new [](size_t size) throw(); 99 void operator delete(void* p); 100 void operator delete [](void* p); 101 }; 102 103 // For iteration over MemRegion's. 104 105 class MemRegionClosure : public StackObj { 106 public: 107 virtual void do_MemRegion(MemRegion mr) = 0; 108 }; 109 110 // A ResourceObj version of MemRegionClosure 111 112 class MemRegionClosureRO: public MemRegionClosure { 113 public: 114 void* operator new(size_t size, ResourceObj::allocation_type type, MEMFLAGS flags) throw() { 115 return ResourceObj::operator new(size, type, flags); 116 } 117 void* operator new(size_t size, Arena *arena) throw() { 118 return ResourceObj::operator new(size, arena); 119 } 120 void* operator new(size_t size) throw() { 121 return ResourceObj::operator new(size); 122 } 123 124 void operator delete(void* p) {} // nothing to do 125 }; 126 127 #endif // SHARE_VM_MEMORY_MEMREGION_HPP