0
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1 /*
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2 * Copyright 1997-2005 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/_relocator.cpp.incl"
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27
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28 #define MAX_METHOD_LENGTH 65535
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29
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30 #define MAX_SHORT ((1 << 15) - 1)
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31 #define MIN_SHORT (- (1 << 15))
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32
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33 // Encapsulates a code change request. There are 3 types.
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34 // General instruction, jump instruction, and table/lookup switches
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35 //
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36 class ChangeItem : public ResourceObj {
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37 int _bci;
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38 public:
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39 ChangeItem(int bci) { _bci = bci; }
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40 virtual bool handle_code_change(Relocator *r) = 0;
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41
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42 // type info
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43 virtual bool is_widen() { return false; }
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44 virtual bool is_jump_widen() { return false; }
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45 virtual bool is_switch_pad() { return false; }
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46
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47 // accessors
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48 int bci() { return _bci; }
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49 void relocate(int break_bci, int delta) { if (_bci > break_bci) { _bci += delta; } }
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50
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51 virtual bool adjust(int bci, int delta) { return false; }
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52
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53 // debug
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54 virtual void print() = 0;
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55 };
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56
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57 class ChangeWiden : public ChangeItem {
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58 int _new_ilen; // New length of instruction at bci
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59 u_char* _inst_buffer; // New bytecodes
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60 public:
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61 ChangeWiden(int bci, int new_ilen, u_char* inst_buffer) : ChangeItem(bci) {
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62 _new_ilen = new_ilen;
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63 _inst_buffer = inst_buffer;
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64 }
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65
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66 // Callback to do instruction
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67 bool handle_code_change(Relocator *r) { return r->handle_widen(bci(), _new_ilen, _inst_buffer); };
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68
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69 bool is_widen() { return true; }
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70
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71 void print() { tty->print_cr("ChangeWiden. bci: %d New_ilen: %d", bci(), _new_ilen); }
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72 };
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73
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74 class ChangeJumpWiden : public ChangeItem {
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75 int _delta; // New length of instruction at bci
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76 public:
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77 ChangeJumpWiden(int bci, int delta) : ChangeItem(bci) { _delta = delta; }
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78
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79 // Callback to do instruction
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80 bool handle_code_change(Relocator *r) { return r->handle_jump_widen(bci(), _delta); };
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81
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82 bool is_jump_widen() { return true; }
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83
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84 // If the bci matches, adjust the delta in the change jump request.
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85 bool adjust(int jump_bci, int delta) {
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86 if (bci() == jump_bci) {
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87 if (_delta > 0)
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88 _delta += delta;
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89 else
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90 _delta -= delta;
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91 return true;
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92 }
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93 return false;
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94 }
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95
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96 void print() { tty->print_cr("ChangeJumpWiden. bci: %d Delta: %d", bci(), _delta); }
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97 };
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98
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99 class ChangeSwitchPad : public ChangeItem {
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100 int _padding;
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101 bool _is_lookup_switch;
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102 public:
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103 ChangeSwitchPad(int bci, int padding, bool is_lookup_switch) : ChangeItem(bci) {
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104 _padding = padding;
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105 _is_lookup_switch = is_lookup_switch;
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106 }
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107
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108 // Callback to do instruction
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109 bool handle_code_change(Relocator *r) { return r->handle_switch_pad(bci(), _padding, _is_lookup_switch); };
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110
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111 bool is_switch_pad() { return true; }
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112 int padding() { return _padding; }
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113 bool is_lookup_switch() { return _is_lookup_switch; }
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114
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115 void print() { tty->print_cr("ChangeSwitchPad. bci: %d Padding: %d IsLookupSwitch: %d", bci(), _padding, _is_lookup_switch); }
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116 };
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117
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118 //-----------------------------------------------------------------------------------------------------------
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119 // Relocator code
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120
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121 Relocator::Relocator(methodHandle m, RelocatorListener* listener) {
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122 set_method(m);
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123 set_code_length(method()->code_size());
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124 set_code_array(NULL);
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125 // Allocate code array and copy bytecodes
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126 if (!expand_code_array(0)) {
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127 // Should have at least MAX_METHOD_LENGTH available or the verifier
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128 // would have failed.
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129 ShouldNotReachHere();
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130 }
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131 set_compressed_line_number_table(NULL);
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132 set_compressed_line_number_table_size(0);
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133 _listener = listener;
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134 }
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135
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136 // size is the new size of the instruction at bci. Hence, if size is less than the current
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137 // instruction sice, we will shrink the code.
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138 methodHandle Relocator::insert_space_at(int bci, int size, u_char inst_buffer[], TRAPS) {
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139 _changes = new GrowableArray<ChangeItem*> (10);
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140 _changes->push(new ChangeWiden(bci, size, inst_buffer));
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141
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142 if (TraceRelocator) {
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143 tty->print_cr("Space at: %d Size: %d", bci, size);
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144 _method->print();
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145 _method->print_codes();
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146 tty->print_cr("-------------------------------------------------");
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147 }
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148
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149 if (!handle_code_changes()) return methodHandle();
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150
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151 // Construct the new method
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152 methodHandle new_method = methodOopDesc::clone_with_new_data(method(),
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153 code_array(), code_length(),
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154 compressed_line_number_table(),
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155 compressed_line_number_table_size(),
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156 CHECK_(methodHandle()));
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157 set_method(new_method);
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158
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159 if (TraceRelocator) {
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160 tty->print_cr("-------------------------------------------------");
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161 tty->print_cr("new method");
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162 _method->print_codes();
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163 }
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164
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165 return new_method;
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166 }
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167
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168
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169 bool Relocator::handle_code_changes() {
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170 assert(_changes != NULL, "changes vector must be initialized");
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171
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172 while (!_changes->is_empty()) {
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173 // Inv: everything is aligned.
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174 ChangeItem* ci = _changes->first();
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175
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176 if (TraceRelocator) {
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177 ci->print();
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178 }
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179
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180 // Execute operation
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181 if (!ci->handle_code_change(this)) return false;
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182
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183 // Shuffel items up
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184 for (int index = 1; index < _changes->length(); index++) {
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185 _changes->at_put(index-1, _changes->at(index));
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186 }
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187 _changes->pop();
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188 }
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189 return true;
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190 }
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191
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192
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193 bool Relocator::is_opcode_lookupswitch(Bytecodes::Code bc) {
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194 switch (bc) {
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195 case Bytecodes::_tableswitch: return false;
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196 case Bytecodes::_lookupswitch: // not rewritten on ia64
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197 case Bytecodes::_fast_linearswitch: // rewritten _lookupswitch
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198 case Bytecodes::_fast_binaryswitch: return true; // rewritten _lookupswitch
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199 default: ShouldNotReachHere();
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200 }
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201 return true; // dummy
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202 }
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203
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204 // We need a special instruction size method, since lookupswitches and tableswitches might not be
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205 // properly alligned during relocation
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206 int Relocator::rc_instr_len(int bci) {
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207 Bytecodes::Code bc= code_at(bci);
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208 switch (bc) {
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209 // In the case of switch instructions, see if we have the original
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210 // padding recorded.
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211 case Bytecodes::_tableswitch:
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212 case Bytecodes::_lookupswitch:
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213 case Bytecodes::_fast_linearswitch:
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214 case Bytecodes::_fast_binaryswitch:
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215 {
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216 int pad = get_orig_switch_pad(bci, is_opcode_lookupswitch(bc));
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217 if (pad == -1) {
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218 return instruction_length_at(bci);
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219 }
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220 // Otherwise, depends on the switch type.
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221 switch (bc) {
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222 case Bytecodes::_tableswitch: {
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223 int lo = int_at(bci + 1 + pad + 4 * 1);
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224 int hi = int_at(bci + 1 + pad + 4 * 2);
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225 int n = hi - lo + 1;
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226 return 1 + pad + 4*(3 + n);
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227 }
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228 case Bytecodes::_lookupswitch:
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229 case Bytecodes::_fast_linearswitch:
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230 case Bytecodes::_fast_binaryswitch: {
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231 int npairs = int_at(bci + 1 + pad + 4 * 1);
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232 return 1 + pad + 4*(2 + 2*npairs);
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233 }
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234 default:
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235 ShouldNotReachHere();
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236 }
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237 }
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238 }
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239 return instruction_length_at(bci);
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240 }
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241
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242 // If a change item is recorded for "pc", with type "ct", returns the
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243 // associated padding, else -1.
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244 int Relocator::get_orig_switch_pad(int bci, bool is_lookup_switch) {
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245 for (int k = 0; k < _changes->length(); k++) {
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246 ChangeItem* ci = _changes->at(k);
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247 if (ci->is_switch_pad()) {
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248 ChangeSwitchPad* csp = (ChangeSwitchPad*)ci;
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249 if (csp->is_lookup_switch() == is_lookup_switch && csp->bci() == bci) {
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250 return csp->padding();
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251 }
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252 }
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253 }
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254 return -1;
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255 }
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256
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257
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258 // Push a ChangeJumpWiden if it doesn't already exist on the work queue,
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259 // otherwise adjust the item already there by delta. The calculation for
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260 // new_delta is wrong for this because it uses the offset stored in the
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261 // code stream itself which wasn't fixed when item was pushed on the work queue.
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262 void Relocator::push_jump_widen(int bci, int delta, int new_delta) {
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263 for (int j = 0; j < _changes->length(); j++) {
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264 ChangeItem* ci = _changes->at(j);
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265 if (ci->adjust(bci, delta)) return;
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266 }
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267 _changes->push(new ChangeJumpWiden(bci, new_delta));
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268 }
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269
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270
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271 // The current instruction of "c" is a jump; one of its offset starts
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272 // at "offset" and is a short if "isShort" is "TRUE",
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273 // and an integer otherwise. If the jump crosses "breakPC", change
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274 // the span of the jump by "delta".
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275 void Relocator::change_jump(int bci, int offset, bool is_short, int break_bci, int delta) {
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276 int bci_delta = (is_short) ? short_at(offset) : int_at(offset);
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277 int targ = bci + bci_delta;
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278
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279 if ((bci <= break_bci && targ > break_bci) ||
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280 (bci > break_bci && targ <= break_bci)) {
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281 int new_delta;
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282 if (bci_delta > 0)
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283 new_delta = bci_delta + delta;
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284 else
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285 new_delta = bci_delta - delta;
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286
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287 if (is_short && ((new_delta > MAX_SHORT) || new_delta < MIN_SHORT)) {
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288 push_jump_widen(bci, delta, new_delta);
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289 } else if (is_short) {
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290 short_at_put(offset, new_delta);
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291 } else {
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292 int_at_put(offset, new_delta);
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293 }
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294 }
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295 }
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296
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297
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298 // Changes all jumps crossing "break_bci" by "delta". May enqueue things
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299 // on "rc->changes"
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300 void Relocator::change_jumps(int break_bci, int delta) {
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301 int bci = 0;
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302 Bytecodes::Code bc;
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303 // Now, adjust any affected instructions.
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304 while (bci < code_length()) {
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305 switch (bc= code_at(bci)) {
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306 case Bytecodes::_ifeq:
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307 case Bytecodes::_ifne:
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308 case Bytecodes::_iflt:
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309 case Bytecodes::_ifge:
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310 case Bytecodes::_ifgt:
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311 case Bytecodes::_ifle:
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312 case Bytecodes::_if_icmpeq:
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313 case Bytecodes::_if_icmpne:
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314 case Bytecodes::_if_icmplt:
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315 case Bytecodes::_if_icmpge:
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316 case Bytecodes::_if_icmpgt:
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317 case Bytecodes::_if_icmple:
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318 case Bytecodes::_if_acmpeq:
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319 case Bytecodes::_if_acmpne:
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320 case Bytecodes::_ifnull:
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321 case Bytecodes::_ifnonnull:
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322 case Bytecodes::_goto:
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323 case Bytecodes::_jsr:
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324 change_jump(bci, bci+1, true, break_bci, delta);
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325 break;
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326 case Bytecodes::_goto_w:
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327 case Bytecodes::_jsr_w:
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328 change_jump(bci, bci+1, false, break_bci, delta);
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329 break;
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330 case Bytecodes::_tableswitch:
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331 case Bytecodes::_lookupswitch:
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332 case Bytecodes::_fast_linearswitch:
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333 case Bytecodes::_fast_binaryswitch: {
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334 int recPad = get_orig_switch_pad(bci, (bc != Bytecodes::_tableswitch));
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335 int oldPad = (recPad != -1) ? recPad : align(bci+1) - (bci+1);
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336 if (bci > break_bci) {
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337 int new_bci = bci + delta;
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338 int newPad = align(new_bci+1) - (new_bci+1);
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339 // Do we need to check the padding?
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340 if (newPad != oldPad) {
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341 if (recPad == -1) {
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342 _changes->push(new ChangeSwitchPad(bci, oldPad, (bc != Bytecodes::_tableswitch)));
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343 }
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344 }
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345 }
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346
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347 // Then the rest, which depend on the kind of switch.
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348 switch (bc) {
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349 case Bytecodes::_tableswitch: {
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350 change_jump(bci, bci +1 + oldPad, false, break_bci, delta);
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351 // We cannot use the Bytecode_tableswitch abstraction, since the padding might not be correct.
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352 int lo = int_at(bci + 1 + oldPad + 4 * 1);
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353 int hi = int_at(bci + 1 + oldPad + 4 * 2);
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354 int n = hi - lo + 1;
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355 for (int k = 0; k < n; k++) {
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356 change_jump(bci, bci +1 + oldPad + 4*(k+3), false, break_bci, delta);
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357 }
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358 // Special next-bci calculation here...
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359 bci += 1 + oldPad + (n+3)*4;
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360 continue;
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361 }
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362 case Bytecodes::_lookupswitch:
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363 case Bytecodes::_fast_linearswitch:
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364 case Bytecodes::_fast_binaryswitch: {
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365 change_jump(bci, bci +1 + oldPad, false, break_bci, delta);
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366 // We cannot use the Bytecode_lookupswitch abstraction, since the padding might not be correct.
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367 int npairs = int_at(bci + 1 + oldPad + 4 * 1);
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368 for (int k = 0; k < npairs; k++) {
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369 change_jump(bci, bci + 1 + oldPad + 4*(2 + 2*k + 1), false, break_bci, delta);
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370 }
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371 /* Special next-bci calculation here... */
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372 bci += 1 + oldPad + (2 + (npairs*2))*4;
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373 continue;
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374 }
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375 default:
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376 ShouldNotReachHere();
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377 }
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378 }
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379 default:
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380 break;
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381 }
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382 bci += rc_instr_len(bci);
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383 }
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384 }
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385
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386 // The width of instruction at "pc" is changing by "delta". Adjust the
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387 // exception table, if any, of "rc->mb".
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388 void Relocator::adjust_exception_table(int bci, int delta) {
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389 typeArrayOop table = method()->exception_table();
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390 for (int index = 0; index < table->length(); index +=4) {
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391 if (table->int_at(index) > bci) {
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392 table->int_at_put(index+0, table->int_at(index+0) + delta);
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393 table->int_at_put(index+1, table->int_at(index+1) + delta);
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394 } else if (bci < table->int_at(index+1)) {
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395 table->int_at_put(index+1, table->int_at(index+1) + delta);
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396 }
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397 if (table->int_at(index+2) > bci)
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398 table->int_at_put(index+2, table->int_at(index+2) + delta);
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399 }
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400 }
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401
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402
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403 // The width of instruction at "bci" is changing by "delta". Adjust the line number table.
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404 void Relocator::adjust_line_no_table(int bci, int delta) {
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405 if (method()->has_linenumber_table()) {
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406 CompressedLineNumberReadStream reader(method()->compressed_linenumber_table());
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407 CompressedLineNumberWriteStream writer(64); // plenty big for most line number tables
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408 while (reader.read_pair()) {
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409 int adjustment = (reader.bci() > bci) ? delta : 0;
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410 writer.write_pair(reader.bci() + adjustment, reader.line());
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411 }
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412 writer.write_terminator();
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413 set_compressed_line_number_table(writer.buffer());
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414 set_compressed_line_number_table_size(writer.position());
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415 }
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416 }
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417
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418
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419 // The width of instruction at "bci" is changing by "delta". Adjust the local variable table.
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420 void Relocator::adjust_local_var_table(int bci, int delta) {
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421 int localvariable_table_length = method()->localvariable_table_length();
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422 if (localvariable_table_length > 0) {
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423 LocalVariableTableElement* table = method()->localvariable_table_start();
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424 for (int i = 0; i < localvariable_table_length; i++) {
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425 u2 current_bci = table[i].start_bci;
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426 if (current_bci > bci) {
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427 table[i].start_bci = current_bci + delta;
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428 } else {
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429 u2 current_length = table[i].length;
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430 if (current_bci + current_length > bci) {
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431 table[i].length = current_length + delta;
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432 }
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433 }
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434 }
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435 }
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436 }
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437
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438
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439 bool Relocator::expand_code_array(int delta) {
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440 int length = MAX2(code_length() + delta, code_length() * (100+code_slop_pct()) / 100);
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441
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442 if (length > MAX_METHOD_LENGTH) {
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443 if (delta == 0 && code_length() <= MAX_METHOD_LENGTH) {
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444 length = MAX_METHOD_LENGTH;
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445 } else {
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446 return false;
|
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447 }
|
|
448 }
|
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449
|
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450 unsigned char* new_code_array = NEW_RESOURCE_ARRAY(unsigned char, length);
|
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451 if (!new_code_array) return false;
|
|
452
|
|
453 // Expanding current array
|
|
454 if (code_array() != NULL) {
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455 memcpy(new_code_array, code_array(), code_length());
|
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456 } else {
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457 // Initial copy. Copy directly from methodOop
|
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458 memcpy(new_code_array, method()->code_base(), code_length());
|
|
459 }
|
|
460
|
|
461 set_code_array(new_code_array);
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462 set_code_array_length(length);
|
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463
|
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464 return true;
|
|
465 }
|
|
466
|
|
467
|
|
468 // The instruction at "bci", whose size is "ilen", is changing size by
|
|
469 // "delta". Reallocate, move code, recalculate jumps, and enqueue
|
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470 // change items as necessary.
|
|
471 bool Relocator::relocate_code(int bci, int ilen, int delta) {
|
|
472 int next_bci = bci + ilen;
|
|
473 if (delta > 0 && code_length() + delta > code_array_length()) {
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|
474 // Expand allocated code space, if necessary.
|
|
475 if (!expand_code_array(delta)) {
|
|
476 return false;
|
|
477 }
|
|
478 }
|
|
479
|
|
480 // We require 4-byte alignment of code arrays.
|
|
481 assert(((intptr_t)code_array() & 3) == 0, "check code alignment");
|
|
482 // Change jumps before doing the copying; this routine requires aligned switches.
|
|
483 change_jumps(bci, delta);
|
|
484
|
|
485 // In case we have shrunken a tableswitch/lookupswitch statement, we store the last
|
|
486 // bytes that get overwritten. We have to copy the bytes after the change_jumps method
|
|
487 // has been called, since it is likly to update last offset in a tableswitch/lookupswitch
|
|
488 if (delta < 0) {
|
|
489 assert(delta>=-3, "we cannot overwrite more than 3 bytes");
|
|
490 memcpy(_overwrite, addr_at(bci + ilen + delta), -delta);
|
|
491 }
|
|
492
|
|
493 memmove(addr_at(next_bci + delta), addr_at(next_bci), code_length() - next_bci);
|
|
494 set_code_length(code_length() + delta);
|
|
495 // Also adjust exception tables...
|
|
496 adjust_exception_table(bci, delta);
|
|
497 // Line number tables...
|
|
498 adjust_line_no_table(bci, delta);
|
|
499 // And local variable table...
|
|
500 adjust_local_var_table(bci, delta);
|
|
501
|
|
502 // Relocate the pending change stack...
|
|
503 for (int j = 0; j < _changes->length(); j++) {
|
|
504 ChangeItem* ci = _changes->at(j);
|
|
505 ci->relocate(bci, delta);
|
|
506 }
|
|
507
|
|
508 // Notify any listeners about code relocation
|
|
509 notify(bci, delta, code_length());
|
|
510
|
|
511 return true;
|
|
512 }
|
|
513
|
|
514 // relocate a general instruction. Called by ChangeWiden class
|
|
515 bool Relocator::handle_widen(int bci, int new_ilen, u_char inst_buffer[]) {
|
|
516 int ilen = rc_instr_len(bci);
|
|
517 if (!relocate_code(bci, ilen, new_ilen - ilen))
|
|
518 return false;
|
|
519
|
|
520 // Insert new bytecode(s)
|
|
521 for(int k = 0; k < new_ilen; k++) {
|
|
522 code_at_put(bci + k, (Bytecodes::Code)inst_buffer[k]);
|
|
523 }
|
|
524
|
|
525 return true;
|
|
526 }
|
|
527
|
|
528 // handle jump_widen instruction. Called be ChangeJumpWiden class
|
|
529 bool Relocator::handle_jump_widen(int bci, int delta) {
|
|
530 int ilen = rc_instr_len(bci);
|
|
531
|
|
532 Bytecodes::Code bc = code_at(bci);
|
|
533 switch (bc) {
|
|
534 case Bytecodes::_ifeq:
|
|
535 case Bytecodes::_ifne:
|
|
536 case Bytecodes::_iflt:
|
|
537 case Bytecodes::_ifge:
|
|
538 case Bytecodes::_ifgt:
|
|
539 case Bytecodes::_ifle:
|
|
540 case Bytecodes::_if_icmpeq:
|
|
541 case Bytecodes::_if_icmpne:
|
|
542 case Bytecodes::_if_icmplt:
|
|
543 case Bytecodes::_if_icmpge:
|
|
544 case Bytecodes::_if_icmpgt:
|
|
545 case Bytecodes::_if_icmple:
|
|
546 case Bytecodes::_if_acmpeq:
|
|
547 case Bytecodes::_if_acmpne:
|
|
548 case Bytecodes::_ifnull:
|
|
549 case Bytecodes::_ifnonnull: {
|
|
550 const int goto_length = Bytecodes::length_for(Bytecodes::_goto);
|
|
551
|
|
552 // If 'if' points to the next bytecode after goto, it's already handled.
|
|
553 // it shouldn't be.
|
|
554 assert (short_at(bci+1) != ilen+goto_length, "if relocation already handled");
|
|
555 assert(ilen == 3, "check length");
|
|
556
|
|
557 // Convert to 0 if <cond> goto 6
|
|
558 // 3 _goto 11
|
|
559 // 6 _goto_w <wide delta offset>
|
|
560 // 11 <else code>
|
|
561 const int goto_w_length = Bytecodes::length_for(Bytecodes::_goto_w);
|
|
562 const int add_bci = goto_length + goto_w_length;
|
|
563
|
|
564 if (!relocate_code(bci, 3, /*delta*/add_bci)) return false;
|
|
565
|
|
566 // if bytecode points to goto_w instruction
|
|
567 short_at_put(bci + 1, ilen + goto_length);
|
|
568
|
|
569 int cbci = bci + ilen;
|
|
570 // goto around
|
|
571 code_at_put(cbci, Bytecodes::_goto);
|
|
572 short_at_put(cbci + 1, add_bci);
|
|
573 // goto_w <wide delta>
|
|
574 cbci = cbci + goto_length;
|
|
575 code_at_put(cbci, Bytecodes::_goto_w);
|
|
576 if (delta > 0) {
|
|
577 delta += 2; // goto_w is 2 bytes more than "if" code
|
|
578 } else {
|
|
579 delta -= ilen+goto_length; // branch starts at goto_w offset
|
|
580 }
|
|
581 int_at_put(cbci + 1, delta);
|
|
582 break;
|
|
583
|
|
584 }
|
|
585 case Bytecodes::_goto:
|
|
586 case Bytecodes::_jsr:
|
|
587 assert(ilen == 3, "check length");
|
|
588
|
|
589 if (!relocate_code(bci, 3, 2)) return false;
|
|
590 if (bc == Bytecodes::_goto)
|
|
591 code_at_put(bci, Bytecodes::_goto_w);
|
|
592 else
|
|
593 code_at_put(bci, Bytecodes::_jsr_w);
|
|
594
|
|
595 // If it's a forward jump, add 2 for the widening.
|
|
596 if (delta > 0) delta += 2;
|
|
597 int_at_put(bci + 1, delta);
|
|
598 break;
|
|
599
|
|
600 default: ShouldNotReachHere();
|
|
601 }
|
|
602
|
|
603 return true;
|
|
604 }
|
|
605
|
|
606 // handle lookup/table switch instructions. Called be ChangeSwitchPad class
|
|
607 bool Relocator::handle_switch_pad(int bci, int old_pad, bool is_lookup_switch) {
|
|
608 int ilen = rc_instr_len(bci);
|
|
609 int new_pad = align(bci+1) - (bci+1);
|
|
610 int pad_delta = new_pad - old_pad;
|
|
611 if (pad_delta != 0) {
|
|
612 int len;
|
|
613 if (!is_lookup_switch) {
|
|
614 int low = int_at(bci+1+old_pad+4);
|
|
615 int high = int_at(bci+1+old_pad+8);
|
|
616 len = high-low+1 + 3; // 3 for default, hi, lo.
|
|
617 } else {
|
|
618 int npairs = int_at(bci+1+old_pad+4);
|
|
619 len = npairs*2 + 2; // 2 for default, npairs.
|
|
620 }
|
|
621 // Because "relocateCode" does a "changeJumps" loop,
|
|
622 // which parses instructions to determine their length,
|
|
623 // we need to call that before messing with the current
|
|
624 // instruction. Since it may also overwrite the current
|
|
625 // instruction when moving down, remember the possibly
|
|
626 // overwritten part.
|
|
627
|
|
628 // Move the code following the instruction...
|
|
629 if (!relocate_code(bci, ilen, pad_delta)) return false;
|
|
630
|
|
631 if (pad_delta < 0) {
|
|
632 // Move the shrunken instruction down.
|
|
633 memmove(addr_at(bci + 1 + new_pad),
|
|
634 addr_at(bci + 1 + old_pad),
|
|
635 len * 4 + pad_delta);
|
|
636 memmove(addr_at(bci + 1 + new_pad + len*4 + pad_delta),
|
|
637 _overwrite, -pad_delta);
|
|
638 } else {
|
|
639 assert(pad_delta > 0, "check");
|
|
640 // Move the expanded instruction up.
|
|
641 memmove(addr_at(bci +1 + new_pad),
|
|
642 addr_at(bci +1 + old_pad),
|
|
643 len * 4);
|
|
644 }
|
|
645 }
|
|
646 return true;
|
|
647 }
|