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1 /*
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2 * Copyright 1998-2005 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 # include "incls/_precompiled.incl"
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26 # include "incls/_rewriter.cpp.incl"
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27
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28
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29 // Computes an index_map (new_index -> original_index) for contant pool entries
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30 // that are referred to by the interpreter at runtime via the constant pool cache.
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31 void Rewriter::compute_index_maps(constantPoolHandle pool, intArray*& index_map, intStack*& inverse_index_map) {
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32 const int length = pool->length();
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33 index_map = new intArray(length, -1);
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34 // Choose an initial value large enough that we don't get frequent
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35 // calls to grow().
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36 inverse_index_map = new intStack(length / 2);
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37 for (int i = 0; i < length; i++) {
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38 switch (pool->tag_at(i).value()) {
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39 case JVM_CONSTANT_Fieldref : // fall through
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40 case JVM_CONSTANT_Methodref : // fall through
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41 case JVM_CONSTANT_InterfaceMethodref: {
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42 index_map->at_put(i, inverse_index_map->length());
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43 inverse_index_map->append(i);
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44 }
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45 }
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46 }
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47 }
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48
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49
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50 // Creates a constant pool cache given an inverse_index_map
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51 constantPoolCacheHandle Rewriter::new_constant_pool_cache(intArray& inverse_index_map, TRAPS) {
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52 const int length = inverse_index_map.length();
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53 constantPoolCacheOop cache = oopFactory::new_constantPoolCache(length, CHECK_(constantPoolCacheHandle()));
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54 cache->initialize(inverse_index_map);
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55 return constantPoolCacheHandle(THREAD, cache);
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56 }
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57
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58
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59
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60 // The new finalization semantics says that registration of
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61 // finalizable objects must be performed on successful return from the
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62 // Object.<init> constructor. We could implement this trivially if
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63 // <init> were never rewritten but since JVMTI allows this to occur, a
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64 // more complicated solution is required. A special return bytecode
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65 // is used only by Object.<init> to signal the finalization
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66 // registration point. Additionally local 0 must be preserved so it's
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67 // available to pass to the registration function. For simplicty we
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68 // require that local 0 is never overwritten so it's available as an
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69 // argument for registration.
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70
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71 void Rewriter::rewrite_Object_init(methodHandle method, TRAPS) {
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72 RawBytecodeStream bcs(method);
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73 while (!bcs.is_last_bytecode()) {
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74 Bytecodes::Code opcode = bcs.raw_next();
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75 switch (opcode) {
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76 case Bytecodes::_return: *bcs.bcp() = Bytecodes::_return_register_finalizer; break;
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77
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78 case Bytecodes::_istore:
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79 case Bytecodes::_lstore:
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80 case Bytecodes::_fstore:
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81 case Bytecodes::_dstore:
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82 case Bytecodes::_astore:
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83 if (bcs.get_index() != 0) continue;
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84
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85 // fall through
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86 case Bytecodes::_istore_0:
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87 case Bytecodes::_lstore_0:
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88 case Bytecodes::_fstore_0:
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89 case Bytecodes::_dstore_0:
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90 case Bytecodes::_astore_0:
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91 THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(),
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92 "can't overwrite local 0 in Object.<init>");
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93 break;
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94 }
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95 }
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96 }
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97
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98
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99 // Rewrites a method given the index_map information
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100 methodHandle Rewriter::rewrite_method(methodHandle method, intArray& index_map, TRAPS) {
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101
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102 int nof_jsrs = 0;
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103 bool has_monitor_bytecodes = false;
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104
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105 {
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106 // We cannot tolerate a GC in this block, because we've
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107 // cached the bytecodes in 'code_base'. If the methodOop
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108 // moves, the bytecodes will also move.
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109 No_Safepoint_Verifier nsv;
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110 Bytecodes::Code c;
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111
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112 // Bytecodes and their length
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113 const address code_base = method->code_base();
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114 const int code_length = method->code_size();
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115
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116 int bc_length;
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117 for (int bci = 0; bci < code_length; bci += bc_length) {
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118 address bcp = code_base + bci;
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119 c = (Bytecodes::Code)(*bcp);
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120
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121 // Since we have the code, see if we can get the length
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122 // directly. Some more complicated bytecodes will report
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123 // a length of zero, meaning we need to make another method
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124 // call to calculate the length.
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125 bc_length = Bytecodes::length_for(c);
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126 if (bc_length == 0) {
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127 bc_length = Bytecodes::length_at(bcp);
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128
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129 // length_at will put us at the bytecode after the one modified
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130 // by 'wide'. We don't currently examine any of the bytecodes
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131 // modified by wide, but in case we do in the future...
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132 if (c == Bytecodes::_wide) {
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133 c = (Bytecodes::Code)bcp[1];
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134 }
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135 }
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136
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137 assert(bc_length != 0, "impossible bytecode length");
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138
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139 switch (c) {
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140 case Bytecodes::_lookupswitch : {
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141 #ifndef CC_INTERP
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142 Bytecode_lookupswitch* bc = Bytecode_lookupswitch_at(bcp);
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143 bc->set_code(
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144 bc->number_of_pairs() < BinarySwitchThreshold
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145 ? Bytecodes::_fast_linearswitch
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146 : Bytecodes::_fast_binaryswitch
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147 );
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148 #endif
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149 break;
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150 }
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151 case Bytecodes::_getstatic : // fall through
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152 case Bytecodes::_putstatic : // fall through
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153 case Bytecodes::_getfield : // fall through
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154 case Bytecodes::_putfield : // fall through
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155 case Bytecodes::_invokevirtual : // fall through
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156 case Bytecodes::_invokespecial : // fall through
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157 case Bytecodes::_invokestatic : // fall through
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158 case Bytecodes::_invokeinterface: {
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159 address p = bcp + 1;
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160 Bytes::put_native_u2(p, index_map[Bytes::get_Java_u2(p)]);
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161 break;
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162 }
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163 case Bytecodes::_jsr : // fall through
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164 case Bytecodes::_jsr_w : nof_jsrs++; break;
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165 case Bytecodes::_monitorenter : // fall through
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166 case Bytecodes::_monitorexit : has_monitor_bytecodes = true; break;
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167 }
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168 }
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169 }
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170
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171 // Update access flags
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172 if (has_monitor_bytecodes) {
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173 method->set_has_monitor_bytecodes();
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174 }
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175
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176 // The present of a jsr bytecode implies that the method might potentially
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177 // have to be rewritten, so we run the oopMapGenerator on the method
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178 if (nof_jsrs > 0) {
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179 method->set_has_jsrs();
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180 ResolveOopMapConflicts romc(method);
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181 methodHandle original_method = method;
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182 method = romc.do_potential_rewrite(CHECK_(methodHandle()));
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183 if (method() != original_method()) {
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184 // Insert invalid bytecode into original methodOop and set
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185 // interpreter entrypoint, so that a executing this method
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186 // will manifest itself in an easy recognizable form.
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187 address bcp = original_method->bcp_from(0);
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188 *bcp = (u1)Bytecodes::_shouldnotreachhere;
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189 int kind = Interpreter::method_kind(original_method);
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190 original_method->set_interpreter_kind(kind);
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191 }
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192
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193 // Update monitor matching info.
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194 if (romc.monitor_safe()) {
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195 method->set_guaranteed_monitor_matching();
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196 }
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197 }
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198
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199 // Setup method entrypoints for compiler and interpreter
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200 method->link_method(method, CHECK_(methodHandle()));
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201
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202 return method;
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203 }
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204
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205
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206 void Rewriter::rewrite(instanceKlassHandle klass, TRAPS) {
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207 // gather starting points
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208 ResourceMark rm(THREAD);
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209 constantPoolHandle pool (THREAD, klass->constants());
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210 objArrayHandle methods (THREAD, klass->methods());
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211 assert(pool->cache() == NULL, "constant pool cache must not be set yet");
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212
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213 // determine index maps for methodOop rewriting
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214 intArray* index_map = NULL;
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215 intStack* inverse_index_map = NULL;
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216 compute_index_maps(pool, index_map, inverse_index_map);
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217
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218 // allocate constant pool cache
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219 constantPoolCacheHandle cache = new_constant_pool_cache(*inverse_index_map, CHECK);
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220 pool->set_cache(cache());
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221 cache->set_constant_pool(pool());
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222
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223 if (RegisterFinalizersAtInit && klass->name() == vmSymbols::java_lang_Object()) {
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224 int i = methods->length();
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225 while (i-- > 0) {
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226 methodOop method = (methodOop)methods->obj_at(i);
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227 if (method->intrinsic_id() == vmIntrinsics::_Object_init) {
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228 // rewrite the return bytecodes of Object.<init> to register the
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229 // object for finalization if needed.
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230 methodHandle m(THREAD, method);
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231 rewrite_Object_init(m, CHECK);
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232 break;
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233 }
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234 }
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235 }
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236
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237 // rewrite methods
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238 { int i = methods->length();
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239 while (i-- > 0) {
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240 methodHandle m(THREAD, (methodOop)methods->obj_at(i));
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241 m = rewrite_method(m, *index_map, CHECK);
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242 // Method might have gotten rewritten.
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243 methods->obj_at_put(i, m());
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244 }
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245 }
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246 }
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