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1 /*
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2 * Copyright 1997-2006 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 // Blocks
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26
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27 class HeapBlock VALUE_OBJ_CLASS_SPEC {
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28 friend class VMStructs;
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29
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30 public:
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31 struct Header {
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32 size_t _length; // the length in segments
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33 bool _used; // Used bit
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34 };
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35
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36 protected:
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37 union {
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38 Header _header;
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39 int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ];
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40 // pad to 0 mod 8
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41 };
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42
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43 public:
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44 // Initialization
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45 void initialize(size_t length) { _header._length = length; set_used(); }
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46
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47 // Accessors
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48 void* allocated_space() const { return (void*)(this + 1); }
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49 size_t length() const { return _header._length; }
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50
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51 // Used/free
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52 void set_used() { _header._used = true; }
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53 void set_free() { _header._used = false; }
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54 bool free() { return !_header._used; }
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55 };
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56
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57 class FreeBlock: public HeapBlock {
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58 friend class VMStructs;
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59 protected:
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60 FreeBlock* _link;
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61
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62 public:
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63 // Initialization
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64 void initialize(size_t length) { HeapBlock::initialize(length); _link= NULL; }
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65
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66 // Merging
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67 void set_length(size_t l) { _header._length = l; }
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68
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69 // Accessors
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70 FreeBlock* link() const { return _link; }
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71 void set_link(FreeBlock* link) { _link = link; }
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72 };
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73
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74 class CodeHeap : public CHeapObj {
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75 friend class VMStructs;
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76 private:
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77 VirtualSpace _memory; // the memory holding the blocks
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78 VirtualSpace _segmap; // the memory holding the segment map
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79
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80 size_t _number_of_committed_segments;
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81 size_t _number_of_reserved_segments;
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82 size_t _segment_size;
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83 int _log2_segment_size;
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84
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85 size_t _next_segment;
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86
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87 FreeBlock* _freelist;
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88 size_t _free_segments; // No. of segments in freelist
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89
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90 // Helper functions
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91 size_t number_of_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; }
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92 size_t size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; }
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93
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94 size_t segment_for(void* p) const { return ((char*)p - _memory.low()) >> _log2_segment_size; }
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95 HeapBlock* block_at(size_t i) const { return (HeapBlock*)(_memory.low() + (i << _log2_segment_size)); }
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96
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97 void mark_segmap_as_free(size_t beg, size_t end);
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98 void mark_segmap_as_used(size_t beg, size_t end);
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99
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100 // Freelist management helpers
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101 FreeBlock* following_block(FreeBlock *b);
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102 void insert_after(FreeBlock* a, FreeBlock* b);
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103 void merge_right (FreeBlock* a);
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104
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105 // Toplevel freelist management
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106 void add_to_freelist(HeapBlock *b);
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107 FreeBlock* search_freelist(size_t length);
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108
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109 // Iteration helpers
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110 void* next_free(HeapBlock* b) const;
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111 HeapBlock* first_block() const;
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112 HeapBlock* next_block(HeapBlock* b) const;
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113 HeapBlock* block_start(void* p) const;
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114
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115 // to perform additional actions on creation of executable code
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116 void on_code_mapping(char* base, size_t size);
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117
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118 public:
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119 CodeHeap();
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120
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121 // Heap extents
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122 bool reserve(size_t reserved_size, size_t committed_size, size_t segment_size);
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123 void release(); // releases all allocated memory
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124 bool expand_by(size_t size); // expands commited memory by size
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125 void shrink_by(size_t size); // shrinks commited memory by size
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126 void clear(); // clears all heap contents
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127
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128 // Memory allocation
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129 void* allocate (size_t size); // allocates a block of size or returns NULL
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130 void deallocate(void* p); // deallocates a block
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131
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132 // Attributes
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133 void* begin() const { return _memory.low (); }
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134 void* end() const { return _memory.high(); }
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135 bool contains(void* p) const { return begin() <= p && p < end(); }
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136 void* find_start(void* p) const; // returns the block containing p or NULL
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137 size_t alignment_unit() const; // alignment of any block
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138 size_t alignment_offset() const; // offset of first byte of any block, within the enclosing alignment unit
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139 static size_t header_size(); // returns the header size for each heap block
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140
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141 // Returns reserved area high and low addresses
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142 char *low_boundary() const { return _memory.low_boundary (); }
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143 char *high_boundary() const { return _memory.high_boundary(); }
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144
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145 // Iteration
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146
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147 // returns the first block or NULL
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148 void* first() const { return next_free(first_block()); }
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149 // returns the next block given a block p or NULL
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150 void* next(void* p) const { return next_free(next_block(block_start(p))); }
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151
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152 // Statistics
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153 size_t capacity() const;
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154 size_t max_capacity() const;
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155 size_t allocated_capacity() const;
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156 size_t unallocated_capacity() const { return max_capacity() - allocated_capacity(); }
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157
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158 // Debugging
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159 void verify();
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160 void print() PRODUCT_RETURN;
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161 };
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