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1 /*
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2 * Copyright 2000-2005 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 class BciMap;
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26
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27 // methodComparator provides an interface for determining if methods of
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28 // different versions of classes are equivalent or switchable
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29
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30 class MethodComparator {
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31 private:
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32 static BytecodeStream *_s_old, *_s_new;
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33 static constantPoolOop _old_cp, _new_cp;
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34 static BciMap *_bci_map;
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35 static bool _switchable_test;
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36 static GrowableArray<int> *_fwd_jmps;
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37
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38 static bool args_same(Bytecodes::Code c_old, Bytecodes::Code c_new);
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39 static int check_stack_and_locals_size(methodOop old_method, methodOop new_method);
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40
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41 public:
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42 // Check if the new method is equivalent to the old one modulo constant pool (EMCP).
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43 // Intuitive definition: two versions of the same method are EMCP, if they don't differ
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44 // on the source code level. Practically, we check whether the only difference between
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45 // method versions is some constantpool indices embedded into the bytecodes, and whether
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46 // these indices eventually point to the same constants for both method versions.
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47 static bool methods_EMCP(methodOop old_method, methodOop new_method);
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48
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49 static bool methods_switchable(methodOop old_method, methodOop new_method, BciMap &bci_map);
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50 };
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51
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52
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53 // ByteCode Index Map. For two versions of the same method, where the new version may contain
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54 // fragments not found in the old version, provides a mapping from an index of a bytecode in
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55 // the old method to the index of the same bytecode in the new method.
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56
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57 class BciMap {
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58 private:
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59 int *_old_bci, *_new_st_bci, *_new_end_bci;
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60 int _cur_size, _cur_pos;
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61 int _pos;
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62
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63 public:
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64 BciMap() {
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65 _cur_size = 50;
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66 _old_bci = (int*) malloc(sizeof(int) * _cur_size);
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67 _new_st_bci = (int*) malloc(sizeof(int) * _cur_size);
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68 _new_end_bci = (int*) malloc(sizeof(int) * _cur_size);
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69 _cur_pos = 0;
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70 }
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71
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72 ~BciMap() {
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73 free(_old_bci);
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74 free(_new_st_bci);
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75 free(_new_end_bci);
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76 }
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77
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78 // Store the position of an added fragment, e.g.
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79 //
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80 // |<- old_bci
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81 // -----------------------------------------
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82 // Old method |invokevirtual 5|aload 1|...
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83 // -----------------------------------------
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84 //
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85 // |<- new_st_bci |<- new_end_bci
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86 // --------------------------------------------------------------------
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87 // New method |invokevirual 5|aload 2|invokevirtual 6|aload 1|...
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88 // --------------------------------------------------------------------
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89 // ^^^^^^^^^^^^^^^^^^^^^^^^
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90 // Added fragment
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91
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92 void store_fragment_location(int old_bci, int new_st_bci, int new_end_bci) {
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93 if (_cur_pos == _cur_size) {
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94 _cur_size += 10;
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95 _old_bci = (int*) realloc(_old_bci, sizeof(int) * _cur_size);
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96 _new_st_bci = (int*) realloc(_new_st_bci, sizeof(int) * _cur_size);
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97 _new_end_bci = (int*) realloc(_new_end_bci, sizeof(int) * _cur_size);
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98 }
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99 _old_bci[_cur_pos] = old_bci;
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100 _new_st_bci[_cur_pos] = new_st_bci;
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101 _new_end_bci[_cur_pos] = new_end_bci;
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102 _cur_pos++;
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103 }
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104
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105 int new_bci_for_old(int old_bci) {
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106 if (_cur_pos == 0 || old_bci < _old_bci[0]) return old_bci;
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107 _pos = 1;
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108 while (_pos < _cur_pos && old_bci >= _old_bci[_pos])
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109 _pos++;
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110 return _new_end_bci[_pos-1] + (old_bci - _old_bci[_pos-1]);
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111 }
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112
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113 // Test if two indexes - one in the old method and another in the new one - correspond
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114 // to the same bytecode
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115 bool old_and_new_locations_same(int old_dest_bci, int new_dest_bci) {
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116 if (new_bci_for_old(old_dest_bci) == new_dest_bci)
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117 return true;
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118 else if (_old_bci[_pos-1] == old_dest_bci)
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119 return (new_dest_bci == _new_st_bci[_pos-1]);
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120 else return false;
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121 }
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122 };
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