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1 /*
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2 * Copyright 1997-2003 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 // The resource area holds temporary data structures in the VM.
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26 // The actual allocation areas are thread local. Typical usage:
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27 //
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28 // ...
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29 // {
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30 // ResourceMark rm;
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31 // int foo[] = NEW_RESOURCE_ARRAY(int, 64);
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32 // ...
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33 // }
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34 // ...
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35
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36 //------------------------------ResourceArea-----------------------------------
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37 // A ResourceArea is an Arena that supports safe usage of ResourceMark.
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38 class ResourceArea: public Arena {
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39 friend class ResourceMark;
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40 friend class DeoptResourceMark;
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41 debug_only(int _nesting;) // current # of nested ResourceMarks
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42 debug_only(static int _warned;) // to suppress multiple warnings
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43
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44 public:
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45 ResourceArea() {
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46 debug_only(_nesting = 0;)
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47 }
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48
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49 ResourceArea(size_t init_size) : Arena(init_size) {
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50 debug_only(_nesting = 0;);
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51 }
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52
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53 char* allocate_bytes(size_t size) {
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54 #ifdef ASSERT
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55 if (_nesting < 1 && !_warned++)
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56 fatal("memory leak: allocating without ResourceMark");
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57 if (UseMallocOnly) {
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58 // use malloc, but save pointer in res. area for later freeing
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59 char** save = (char**)internal_malloc_4(sizeof(char*));
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60 return (*save = (char*)os::malloc(size));
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61 }
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62 #endif
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63 return (char*)Amalloc(size);
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64 }
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65
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66 debug_only(int nesting() const { return _nesting; });
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67 };
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68
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69
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70 //------------------------------ResourceMark-----------------------------------
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71 // A resource mark releases all resources allocated after it was constructed
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72 // when the destructor is called. Typically used as a local variable.
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73 class ResourceMark: public StackObj {
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74 protected:
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75 ResourceArea *_area; // Resource area to stack allocate
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76 Chunk *_chunk; // saved arena chunk
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77 char *_hwm, *_max;
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78 NOT_PRODUCT(size_t _size_in_bytes;)
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79
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80 void initialize(Thread *thread) {
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81 _area = thread->resource_area();
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82 _chunk = _area->_chunk;
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83 _hwm = _area->_hwm;
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84 _max= _area->_max;
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85 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
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86 debug_only(_area->_nesting++;)
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87 assert( _area->_nesting > 0, "must stack allocate RMs" );
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88 }
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89
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90 public:
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91
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92 #ifndef ASSERT
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93 ResourceMark(Thread *thread) {
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94 assert(thread == Thread::current(), "not the current thread");
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95 initialize(thread);
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96 }
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97 #else
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98 ResourceMark(Thread *thread);
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99 #endif // ASSERT
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100
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101 ResourceMark() { initialize(Thread::current()); }
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102
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103 ResourceMark( ResourceArea *r ) :
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104 _area(r), _chunk(r->_chunk), _hwm(r->_hwm), _max(r->_max) {
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105 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
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106 debug_only(_area->_nesting++;)
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107 assert( _area->_nesting > 0, "must stack allocate RMs" );
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108 }
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109
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110 void reset_to_mark() {
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111 if (UseMallocOnly) free_malloced_objects();
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112
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113 if( _chunk->next() ) // Delete later chunks
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114 _chunk->next_chop();
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115 _area->_chunk = _chunk; // Roll back arena to saved chunk
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116 _area->_hwm = _hwm;
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117 _area->_max = _max;
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118
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119 // clear out this chunk (to detect allocation bugs)
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120 if (ZapResourceArea) memset(_hwm, badResourceValue, _max - _hwm);
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121 _area->set_size_in_bytes(size_in_bytes());
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122 }
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123
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124 ~ResourceMark() {
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125 assert( _area->_nesting > 0, "must stack allocate RMs" );
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126 debug_only(_area->_nesting--;)
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127 reset_to_mark();
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128 }
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129
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130
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131 private:
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132 void free_malloced_objects() PRODUCT_RETURN;
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133 size_t size_in_bytes() NOT_PRODUCT({ return _size_in_bytes; }) PRODUCT_RETURN0;
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134 };
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135
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136 //------------------------------DeoptResourceMark-----------------------------------
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137 // A deopt resource mark releases all resources allocated after it was constructed
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138 // when the destructor is called. Typically used as a local variable. It differs
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139 // from a typical resource more in that it is C-Heap allocated so that deoptimization
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140 // can use data structures that are arena based but are not amenable to vanilla
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141 // ResourceMarks because deoptimization can not use a stack allocated mark. During
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142 // deoptimization we go thru the following steps:
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143 //
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144 // 0: start in assembly stub and call either uncommon_trap/fetch_unroll_info
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145 // 1: create the vframeArray (contains pointers to Resource allocated structures)
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146 // This allocates the DeoptResourceMark.
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147 // 2: return to assembly stub and remove stub frame and deoptee frame and create
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148 // the new skeletal frames.
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149 // 3: push new stub frame and call unpack_frames
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150 // 4: retrieve information from the vframeArray to populate the skeletal frames
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151 // 5: release the DeoptResourceMark
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152 // 6: return to stub and eventually to interpreter
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153 //
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154 // With old style eager deoptimization the vframeArray was created by the vmThread there
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155 // was no way for the vframeArray to contain resource allocated objects and so
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156 // a complex set of data structures to simulate an array of vframes in CHeap memory
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157 // was used. With new style lazy deoptimization the vframeArray is created in the
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158 // the thread that will use it and we can use a much simpler scheme for the vframeArray
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159 // leveraging existing data structures if we simply create a way to manage this one
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160 // special need for a ResourceMark. If ResourceMark simply inherited from CHeapObj
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161 // then existing ResourceMarks would work fine since no one use new to allocate them
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162 // and they would be stack allocated. This leaves open the possibilty of accidental
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163 // misuse so we simple duplicate the ResourceMark functionality here.
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164
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165 class DeoptResourceMark: public CHeapObj {
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166 protected:
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167 ResourceArea *_area; // Resource area to stack allocate
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168 Chunk *_chunk; // saved arena chunk
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169 char *_hwm, *_max;
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170 NOT_PRODUCT(size_t _size_in_bytes;)
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171
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172 void initialize(Thread *thread) {
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173 _area = thread->resource_area();
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174 _chunk = _area->_chunk;
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175 _hwm = _area->_hwm;
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176 _max= _area->_max;
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177 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
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178 debug_only(_area->_nesting++;)
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179 assert( _area->_nesting > 0, "must stack allocate RMs" );
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180 }
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181
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182 public:
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183
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184 #ifndef ASSERT
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185 DeoptResourceMark(Thread *thread) {
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186 assert(thread == Thread::current(), "not the current thread");
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187 initialize(thread);
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188 }
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189 #else
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190 DeoptResourceMark(Thread *thread);
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191 #endif // ASSERT
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192
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193 DeoptResourceMark() { initialize(Thread::current()); }
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194
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195 DeoptResourceMark( ResourceArea *r ) :
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196 _area(r), _chunk(r->_chunk), _hwm(r->_hwm), _max(r->_max) {
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197 NOT_PRODUCT(_size_in_bytes = _area->size_in_bytes();)
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198 debug_only(_area->_nesting++;)
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199 assert( _area->_nesting > 0, "must stack allocate RMs" );
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200 }
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201
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202 void reset_to_mark() {
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203 if (UseMallocOnly) free_malloced_objects();
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204
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205 if( _chunk->next() ) // Delete later chunks
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206 _chunk->next_chop();
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207 _area->_chunk = _chunk; // Roll back arena to saved chunk
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208 _area->_hwm = _hwm;
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209 _area->_max = _max;
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210
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211 // clear out this chunk (to detect allocation bugs)
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212 if (ZapResourceArea) memset(_hwm, badResourceValue, _max - _hwm);
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213 _area->set_size_in_bytes(size_in_bytes());
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214 }
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215
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216 ~DeoptResourceMark() {
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217 assert( _area->_nesting > 0, "must stack allocate RMs" );
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218 debug_only(_area->_nesting--;)
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219 reset_to_mark();
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220 }
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221
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222
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223 private:
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224 void free_malloced_objects() PRODUCT_RETURN;
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225 size_t size_in_bytes() NOT_PRODUCT({ return _size_in_bytes; }) PRODUCT_RETURN0;
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226 };
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