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1 /*
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2 * Copyright 2000-2004 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 // A very simple data structure representing a contigous region
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26 // region of address space.
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27
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28 // Note that MemRegions are passed by value, not by reference.
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29 // The intent is that they remain very small and contain no
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30 // objects.
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31
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32 class MemRegion VALUE_OBJ_CLASS_SPEC {
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33 friend class VMStructs;
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34 private:
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35 HeapWord* _start;
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36 size_t _word_size;
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37
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38 public:
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39 MemRegion() : _start(NULL), _word_size(0) {};
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40 MemRegion(HeapWord* start, size_t word_size) :
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41 _start(start), _word_size(word_size) {};
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42 MemRegion(HeapWord* start, HeapWord* end) :
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43 _start(start), _word_size(pointer_delta(end, start)) {
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44 assert(end >= start, "incorrect constructor arguments");
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45 }
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46
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47 MemRegion(const MemRegion& mr): _start(mr._start), _word_size(mr._word_size) {}
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48
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49 MemRegion intersection(const MemRegion mr2) const;
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50 // regions must overlap or be adjacent
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51 MemRegion _union(const MemRegion mr2) const;
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52 // minus will fail a guarantee if mr2 is interior to this,
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53 // since there's no way to return 2 disjoint regions.
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54 MemRegion minus(const MemRegion mr2) const;
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55
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56 HeapWord* start() const { return _start; }
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57 HeapWord* end() const { return _start + _word_size; }
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58 HeapWord* last() const { return _start + _word_size - 1; }
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59
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60 void set_start(HeapWord* start) { _start = start; }
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61 void set_end(HeapWord* end) { _word_size = pointer_delta(end, _start); }
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62 void set_word_size(size_t word_size) {
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63 _word_size = word_size;
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64 }
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65
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66 bool contains(const MemRegion mr2) const {
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67 return _start <= mr2._start && end() >= mr2.end();
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68 }
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69 bool contains(const void* addr) const {
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70 return addr >= (void*)_start && addr < (void*)end();
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71 }
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72 bool equals(const MemRegion mr2) const {
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73 // first disjunct since we do not have a canonical empty set
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74 return ((is_empty() && mr2.is_empty()) ||
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75 (start() == mr2.start() && end() == mr2.end()));
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76 }
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77
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78 size_t byte_size() const { return _word_size * sizeof(HeapWord); }
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79 size_t word_size() const { return _word_size; }
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80
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81 bool is_empty() const { return word_size() == 0; }
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82 };
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83
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84 // For iteration over MemRegion's.
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85
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86 class MemRegionClosure : public StackObj {
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87 public:
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88 virtual void do_MemRegion(MemRegion mr) = 0;
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89 };
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90
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91 // A ResourceObj version of MemRegionClosure
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92
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93 class MemRegionClosureRO: public MemRegionClosure {
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94 public:
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95 void* operator new(size_t size, ResourceObj::allocation_type type) {
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96 return ResourceObj::operator new(size, type);
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97 }
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98 void* operator new(size_t size, Arena *arena) {
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99 return ResourceObj::operator new(size, arena);
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100 }
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101 void* operator new(size_t size) {
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102 return ResourceObj::operator new(size);
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103 }
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104
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105 void operator delete(void* p) {} // nothing to do
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106 };
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