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1 /* |
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2 * Copyright (c) 2018, 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 #include "precompiled.hpp" |
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26 #include "ci/ciUtilities.hpp" |
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27 #include "gc/shared/cardTable.hpp" |
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28 #include "gc/shared/cardTableBarrierSet.hpp" |
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29 #include "gc/shared/c2/cardTableBarrierSetC2.hpp" |
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30 #include "opto/arraycopynode.hpp" |
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31 #include "opto/graphKit.hpp" |
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32 #include "opto/idealKit.hpp" |
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33 #include "opto/macro.hpp" |
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34 #include "utilities/macros.hpp" |
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35 |
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36 #define __ ideal. |
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37 |
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38 Node* CardTableBarrierSetC2::byte_map_base_node(GraphKit* kit) const { |
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39 // Get base of card map |
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40 jbyte* card_table_base = ci_card_table_address(); |
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41 if (card_table_base != NULL) { |
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42 return kit->makecon(TypeRawPtr::make((address)card_table_base)); |
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43 } else { |
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44 return kit->null(); |
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45 } |
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46 } |
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47 |
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48 // vanilla/CMS post barrier |
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49 // Insert a write-barrier store. This is to let generational GC work; we have |
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50 // to flag all oop-stores before the next GC point. |
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51 void CardTableBarrierSetC2::post_barrier(GraphKit* kit, |
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52 Node* ctl, |
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53 Node* oop_store, |
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54 Node* obj, |
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55 Node* adr, |
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56 uint adr_idx, |
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57 Node* val, |
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58 BasicType bt, |
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59 bool use_precise) const { |
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60 CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(BarrierSet::barrier_set()); |
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61 CardTable* ct = ctbs->card_table(); |
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62 // No store check needed if we're storing a NULL or an old object |
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63 // (latter case is probably a string constant). The concurrent |
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64 // mark sweep garbage collector, however, needs to have all nonNull |
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65 // oop updates flagged via card-marks. |
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66 if (val != NULL && val->is_Con()) { |
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67 // must be either an oop or NULL |
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68 const Type* t = val->bottom_type(); |
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69 if (t == TypePtr::NULL_PTR || t == Type::TOP) |
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70 // stores of null never (?) need barriers |
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71 return; |
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72 } |
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73 |
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74 if (use_ReduceInitialCardMarks() |
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75 && obj == kit->just_allocated_object(kit->control())) { |
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76 // We can skip marks on a freshly-allocated object in Eden. |
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77 // Keep this code in sync with new_deferred_store_barrier() in runtime.cpp. |
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78 // That routine informs GC to take appropriate compensating steps, |
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79 // upon a slow-path allocation, so as to make this card-mark |
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80 // elision safe. |
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81 return; |
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82 } |
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83 |
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84 if (!use_precise) { |
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85 // All card marks for a (non-array) instance are in one place: |
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86 adr = obj; |
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87 } |
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88 // (Else it's an array (or unknown), and we want more precise card marks.) |
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89 assert(adr != NULL, ""); |
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90 |
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91 IdealKit ideal(kit, true); |
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92 |
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93 // Convert the pointer to an int prior to doing math on it |
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94 Node* cast = __ CastPX(__ ctrl(), adr); |
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95 |
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96 // Divide by card size |
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97 Node* card_offset = __ URShiftX( cast, __ ConI(CardTable::card_shift) ); |
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98 |
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99 // Combine card table base and card offset |
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100 Node* card_adr = __ AddP(__ top(), byte_map_base_node(kit), card_offset ); |
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101 |
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102 // Get the alias_index for raw card-mark memory |
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103 int adr_type = Compile::AliasIdxRaw; |
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104 Node* zero = __ ConI(0); // Dirty card value |
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105 |
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106 if (UseCondCardMark) { |
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107 if (ct->scanned_concurrently()) { |
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108 kit->insert_mem_bar(Op_MemBarVolatile, oop_store); |
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109 __ sync_kit(kit); |
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110 } |
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111 // The classic GC reference write barrier is typically implemented |
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112 // as a store into the global card mark table. Unfortunately |
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113 // unconditional stores can result in false sharing and excessive |
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114 // coherence traffic as well as false transactional aborts. |
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115 // UseCondCardMark enables MP "polite" conditional card mark |
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116 // stores. In theory we could relax the load from ctrl() to |
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117 // no_ctrl, but that doesn't buy much latitude. |
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118 Node* card_val = __ load( __ ctrl(), card_adr, TypeInt::BYTE, T_BYTE, adr_type); |
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119 __ if_then(card_val, BoolTest::ne, zero); |
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120 } |
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121 |
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122 // Smash zero into card |
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123 if(!ct->scanned_concurrently()) { |
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124 __ store(__ ctrl(), card_adr, zero, T_BYTE, adr_type, MemNode::unordered); |
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125 } else { |
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126 // Specialized path for CM store barrier |
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127 __ storeCM(__ ctrl(), card_adr, zero, oop_store, adr_idx, T_BYTE, adr_type); |
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128 } |
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129 |
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130 if (UseCondCardMark) { |
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131 __ end_if(); |
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132 } |
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133 |
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134 // Final sync IdealKit and GraphKit. |
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135 kit->final_sync(ideal); |
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136 } |
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137 |
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138 void CardTableBarrierSetC2::clone(GraphKit* kit, Node* src, Node* dst, Node* size, bool is_array) const { |
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139 BarrierSetC2::clone(kit, src, dst, size, is_array); |
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140 const TypePtr* raw_adr_type = TypeRawPtr::BOTTOM; |
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141 |
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142 // If necessary, emit some card marks afterwards. (Non-arrays only.) |
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143 bool card_mark = !is_array && !use_ReduceInitialCardMarks(); |
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144 if (card_mark) { |
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145 assert(!is_array, ""); |
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146 // Put in store barrier for any and all oops we are sticking |
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147 // into this object. (We could avoid this if we could prove |
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148 // that the object type contains no oop fields at all.) |
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149 Node* no_particular_value = NULL; |
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150 Node* no_particular_field = NULL; |
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151 int raw_adr_idx = Compile::AliasIdxRaw; |
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152 post_barrier(kit, kit->control(), |
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153 kit->memory(raw_adr_type), |
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154 dst, |
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155 no_particular_field, |
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156 raw_adr_idx, |
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157 no_particular_value, |
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158 T_OBJECT, |
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159 false); |
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160 } |
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161 } |
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162 |
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163 bool CardTableBarrierSetC2::use_ReduceInitialCardMarks() const { |
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164 return ReduceInitialCardMarks; |
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165 } |
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166 |
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167 bool CardTableBarrierSetC2::is_gc_barrier_node(Node* node) const { |
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168 return ModRefBarrierSetC2::is_gc_barrier_node(node) || node->Opcode() == Op_StoreCM; |
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169 } |
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170 |
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171 void CardTableBarrierSetC2::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { |
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172 assert(node->Opcode() == Op_CastP2X, "ConvP2XNode required"); |
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173 Node *shift = node->unique_out(); |
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174 Node *addp = shift->unique_out(); |
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175 for (DUIterator_Last jmin, j = addp->last_outs(jmin); j >= jmin; --j) { |
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176 Node *mem = addp->last_out(j); |
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177 if (UseCondCardMark && mem->is_Load()) { |
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178 assert(mem->Opcode() == Op_LoadB, "unexpected code shape"); |
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179 // The load is checking if the card has been written so |
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180 // replace it with zero to fold the test. |
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181 macro->replace_node(mem, macro->intcon(0)); |
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182 continue; |
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183 } |
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184 assert(mem->is_Store(), "store required"); |
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185 macro->replace_node(mem, mem->in(MemNode::Memory)); |
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186 } |
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187 } |
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188 |
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189 bool CardTableBarrierSetC2::array_copy_requires_gc_barriers(BasicType type) const { |
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190 return !use_ReduceInitialCardMarks(); |
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191 } |