1 /* 2 * Copyright (c) 2000, 2004, 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 // A very simple data structure representing a contigous region 26 // region of address space. 27 28 // Note that MemRegions are passed by value, not by reference. 29 // The intent is that they remain very small and contain no 30 // objects. 31 32 class MemRegion VALUE_OBJ_CLASS_SPEC { 33 friend class VMStructs; 34 private: 35 HeapWord* _start; 36 size_t _word_size; 37 38 public: 39 MemRegion() : _start(NULL), _word_size(0) {}; 40 MemRegion(HeapWord* start, size_t word_size) : 41 _start(start), _word_size(word_size) {}; 42 MemRegion(HeapWord* start, HeapWord* end) : 43 _start(start), _word_size(pointer_delta(end, start)) { 44 assert(end >= start, "incorrect constructor arguments"); 45 } 46 47 MemRegion(const MemRegion& mr): _start(mr._start), _word_size(mr._word_size) {} 48 49 MemRegion intersection(const MemRegion mr2) const; 50 // regions must overlap or be adjacent 51 MemRegion _union(const MemRegion mr2) const; 52 // minus will fail a guarantee if mr2 is interior to this, 53 // since there's no way to return 2 disjoint regions. 54 MemRegion minus(const MemRegion mr2) const; 55 56 HeapWord* start() const { return _start; } 57 HeapWord* end() const { return _start + _word_size; } 58 HeapWord* last() const { return _start + _word_size - 1; } 59 60 void set_start(HeapWord* start) { _start = start; } 61 void set_end(HeapWord* end) { _word_size = pointer_delta(end, _start); } 62 void set_word_size(size_t word_size) { 63 _word_size = word_size; 64 } 65 66 bool contains(const MemRegion mr2) const { 67 return _start <= mr2._start && end() >= mr2.end(); 68 } 69 bool contains(const void* addr) const { 70 return addr >= (void*)_start && addr < (void*)end(); 71 } 72 bool equals(const MemRegion mr2) const { 73 // first disjunct since we do not have a canonical empty set 74 return ((is_empty() && mr2.is_empty()) || 75 (start() == mr2.start() && end() == mr2.end())); 76 } 77 78 size_t byte_size() const { return _word_size * sizeof(HeapWord); } 79 size_t word_size() const { return _word_size; } 80 81 bool is_empty() const { return word_size() == 0; } 82 }; 83 84 // For iteration over MemRegion's. 85 86 class MemRegionClosure : public StackObj { 87 public: 88 virtual void do_MemRegion(MemRegion mr) = 0; 89 }; 90 91 // A ResourceObj version of MemRegionClosure 92 93 class MemRegionClosureRO: public MemRegionClosure { 94 public: 95 void* operator new(size_t size, ResourceObj::allocation_type type) { 96 return ResourceObj::operator new(size, type); 97 } 98 void* operator new(size_t size, Arena *arena) { 99 return ResourceObj::operator new(size, arena); 100 } 101 void* operator new(size_t size) { 102 return ResourceObj::operator new(size); 103 } 104 105 void operator delete(void* p) {} // nothing to do 106 };