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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 }; |