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1 /* |
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2 * Copyright (c) 2000, 2012, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 * |
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23 */ |
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24 |
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25 #ifndef SHARE_VM_MEMORY_BARRIERSET_HPP |
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26 #define SHARE_VM_MEMORY_BARRIERSET_HPP |
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27 |
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28 #include "memory/memRegion.hpp" |
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29 #include "oops/oopsHierarchy.hpp" |
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30 |
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31 // This class provides the interface between a barrier implementation and |
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32 // the rest of the system. |
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33 |
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34 class BarrierSet: public CHeapObj<mtGC> { |
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35 friend class VMStructs; |
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36 public: |
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37 enum Name { |
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38 ModRef, |
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39 CardTableModRef, |
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40 CardTableExtension, |
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41 G1SATBCT, |
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42 G1SATBCTLogging, |
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43 Other, |
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44 Uninit |
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45 }; |
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46 |
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47 enum Flags { |
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48 None = 0, |
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49 TargetUninitialized = 1 |
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50 }; |
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51 protected: |
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52 int _max_covered_regions; |
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53 Name _kind; |
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54 |
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55 public: |
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56 |
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57 BarrierSet() { _kind = Uninit; } |
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58 // To get around prohibition on RTTI. |
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59 BarrierSet::Name kind() { return _kind; } |
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60 virtual bool is_a(BarrierSet::Name bsn) = 0; |
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61 |
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62 // These operations indicate what kind of barriers the BarrierSet has. |
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63 virtual bool has_read_ref_barrier() = 0; |
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64 virtual bool has_read_prim_barrier() = 0; |
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65 virtual bool has_write_ref_barrier() = 0; |
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66 virtual bool has_write_ref_pre_barrier() = 0; |
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67 virtual bool has_write_prim_barrier() = 0; |
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68 |
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69 // These functions indicate whether a particular access of the given |
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70 // kinds requires a barrier. |
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71 virtual bool read_ref_needs_barrier(void* field) = 0; |
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72 virtual bool read_prim_needs_barrier(HeapWord* field, size_t bytes) = 0; |
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73 virtual bool write_prim_needs_barrier(HeapWord* field, size_t bytes, |
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74 juint val1, juint val2) = 0; |
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75 |
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76 // The first four operations provide a direct implementation of the |
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77 // barrier set. An interpreter loop, for example, could call these |
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78 // directly, as appropriate. |
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79 |
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80 // Invoke the barrier, if any, necessary when reading the given ref field. |
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81 virtual void read_ref_field(void* field) = 0; |
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82 |
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83 // Invoke the barrier, if any, necessary when reading the given primitive |
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84 // "field" of "bytes" bytes in "obj". |
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85 virtual void read_prim_field(HeapWord* field, size_t bytes) = 0; |
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86 |
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87 // Invoke the barrier, if any, necessary when writing "new_val" into the |
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88 // ref field at "offset" in "obj". |
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89 // (For efficiency reasons, this operation is specialized for certain |
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90 // barrier types. Semantically, it should be thought of as a call to the |
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91 // virtual "_work" function below, which must implement the barrier.) |
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92 // First the pre-write versions... |
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93 template <class T> inline void write_ref_field_pre(T* field, oop new_val); |
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94 private: |
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95 // Keep this private so as to catch violations at build time. |
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96 virtual void write_ref_field_pre_work( void* field, oop new_val) { guarantee(false, "Not needed"); }; |
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97 protected: |
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98 virtual void write_ref_field_pre_work( oop* field, oop new_val) {}; |
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99 virtual void write_ref_field_pre_work(narrowOop* field, oop new_val) {}; |
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100 public: |
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101 |
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102 // ...then the post-write version. |
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103 inline void write_ref_field(void* field, oop new_val, bool release = false); |
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104 protected: |
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105 virtual void write_ref_field_work(void* field, oop new_val, bool release = false) = 0; |
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106 public: |
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107 |
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108 // Invoke the barrier, if any, necessary when writing the "bytes"-byte |
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109 // value(s) "val1" (and "val2") into the primitive "field". |
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110 virtual void write_prim_field(HeapWord* field, size_t bytes, |
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111 juint val1, juint val2) = 0; |
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112 |
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113 // Operations on arrays, or general regions (e.g., for "clone") may be |
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114 // optimized by some barriers. |
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115 |
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116 // The first six operations tell whether such an optimization exists for |
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117 // the particular barrier. |
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118 virtual bool has_read_ref_array_opt() = 0; |
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119 virtual bool has_read_prim_array_opt() = 0; |
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120 virtual bool has_write_ref_array_pre_opt() { return true; } |
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121 virtual bool has_write_ref_array_opt() = 0; |
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122 virtual bool has_write_prim_array_opt() = 0; |
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123 |
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124 virtual bool has_read_region_opt() = 0; |
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125 virtual bool has_write_region_opt() = 0; |
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126 |
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127 // These operations should assert false unless the correponding operation |
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128 // above returns true. Otherwise, they should perform an appropriate |
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129 // barrier for an array whose elements are all in the given memory region. |
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130 virtual void read_ref_array(MemRegion mr) = 0; |
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131 virtual void read_prim_array(MemRegion mr) = 0; |
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132 |
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133 // Below length is the # array elements being written |
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134 virtual void write_ref_array_pre(oop* dst, int length, |
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135 bool dest_uninitialized = false) {} |
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136 virtual void write_ref_array_pre(narrowOop* dst, int length, |
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137 bool dest_uninitialized = false) {} |
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138 // Below count is the # array elements being written, starting |
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139 // at the address "start", which may not necessarily be HeapWord-aligned |
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140 inline void write_ref_array(HeapWord* start, size_t count); |
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141 |
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142 // Static versions, suitable for calling from generated code; |
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143 // count is # array elements being written, starting with "start", |
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144 // which may not necessarily be HeapWord-aligned. |
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145 static void static_write_ref_array_pre(HeapWord* start, size_t count); |
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146 static void static_write_ref_array_post(HeapWord* start, size_t count); |
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147 |
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148 protected: |
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149 virtual void write_ref_array_work(MemRegion mr) = 0; |
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150 public: |
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151 virtual void write_prim_array(MemRegion mr) = 0; |
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152 |
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153 virtual void read_region(MemRegion mr) = 0; |
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154 |
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155 // (For efficiency reasons, this operation is specialized for certain |
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156 // barrier types. Semantically, it should be thought of as a call to the |
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157 // virtual "_work" function below, which must implement the barrier.) |
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158 inline void write_region(MemRegion mr); |
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159 protected: |
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160 virtual void write_region_work(MemRegion mr) = 0; |
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161 public: |
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162 |
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163 // Some barrier sets create tables whose elements correspond to parts of |
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164 // the heap; the CardTableModRefBS is an example. Such barrier sets will |
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165 // normally reserve space for such tables, and commit parts of the table |
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166 // "covering" parts of the heap that are committed. The constructor is |
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167 // passed the maximum number of independently committable subregions to |
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168 // be covered, and the "resize_covoered_region" function allows the |
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169 // sub-parts of the heap to inform the barrier set of changes of their |
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170 // sizes. |
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171 BarrierSet(int max_covered_regions) : |
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172 _max_covered_regions(max_covered_regions) {} |
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173 |
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174 // Inform the BarrierSet that the the covered heap region that starts |
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175 // with "base" has been changed to have the given size (possibly from 0, |
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176 // for initialization.) |
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177 virtual void resize_covered_region(MemRegion new_region) = 0; |
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178 |
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179 // If the barrier set imposes any alignment restrictions on boundaries |
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180 // within the heap, this function tells whether they are met. |
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181 virtual bool is_aligned(HeapWord* addr) = 0; |
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182 |
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183 // Print a description of the memory for the barrier set |
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184 virtual void print_on(outputStream* st) const = 0; |
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185 }; |
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186 |
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187 #endif // SHARE_VM_MEMORY_BARRIERSET_HPP |