1 /* 2 * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_PRIMS_METHODCOMPARATOR_HPP 26 #define SHARE_VM_PRIMS_METHODCOMPARATOR_HPP 27 28 #include "interpreter/bytecodeStream.hpp" 29 #include "oops/constantPool.hpp" 30 #include "oops/method.hpp" 31 32 class BciMap; 33 34 // methodComparator provides an interface for determining if methods of 35 // different versions of classes are equivalent or switchable 36 37 class MethodComparator { 38 private: 39 static BytecodeStream *_s_old, *_s_new; 40 static ConstantPool* _old_cp; 41 static ConstantPool* _new_cp; 42 static BciMap *_bci_map; 43 static bool _switchable_test; 44 static GrowableArray<int> *_fwd_jmps; 45 46 static bool args_same(Bytecodes::Code c_old, Bytecodes::Code c_new); 47 static bool pool_constants_same(int cpi_old, int cpi_new); 48 static int check_stack_and_locals_size(Method* old_method, Method* new_method); 49 50 public: 51 // Check if the new method is equivalent to the old one modulo constant pool (EMCP). 52 // Intuitive definition: two versions of the same method are EMCP, if they don't differ 53 // on the source code level. Practically, we check whether the only difference between 54 // method versions is some constantpool indices embedded into the bytecodes, and whether 55 // these indices eventually point to the same constants for both method versions. 56 static bool methods_EMCP(Method* old_method, Method* new_method); 57 58 static bool methods_switchable(Method* old_method, Method* new_method, BciMap &bci_map); 59 }; 60 61 62 // ByteCode Index Map. For two versions of the same method, where the new version may contain 63 // fragments not found in the old version, provides a mapping from an index of a bytecode in 64 // the old method to the index of the same bytecode in the new method. 65 66 class BciMap { 67 private: 68 int *_old_bci, *_new_st_bci, *_new_end_bci; 69 int _cur_size, _cur_pos; 70 int _pos; 71 72 public: 73 BciMap() { 74 _cur_size = 50; 75 _old_bci = (int*) malloc(sizeof(int) * _cur_size); 76 _new_st_bci = (int*) malloc(sizeof(int) * _cur_size); 77 _new_end_bci = (int*) malloc(sizeof(int) * _cur_size); 78 _cur_pos = 0; 79 } 80 81 ~BciMap() { 82 free(_old_bci); 83 free(_new_st_bci); 84 free(_new_end_bci); 85 } 86 87 // Store the position of an added fragment, e.g. 88 // 89 // |<- old_bci 90 // ----------------------------------------- 91 // Old method |invokevirtual 5|aload 1|... 92 // ----------------------------------------- 93 // 94 // |<- new_st_bci |<- new_end_bci 95 // -------------------------------------------------------------------- 96 // New method |invokevirual 5|aload 2|invokevirtual 6|aload 1|... 97 // -------------------------------------------------------------------- 98 // ^^^^^^^^^^^^^^^^^^^^^^^^ 99 // Added fragment 100 101 void store_fragment_location(int old_bci, int new_st_bci, int new_end_bci) { 102 if (_cur_pos == _cur_size) { 103 _cur_size += 10; 104 _old_bci = (int*) realloc(_old_bci, sizeof(int) * _cur_size); 105 _new_st_bci = (int*) realloc(_new_st_bci, sizeof(int) * _cur_size); 106 _new_end_bci = (int*) realloc(_new_end_bci, sizeof(int) * _cur_size); 107 } 108 _old_bci[_cur_pos] = old_bci; 109 _new_st_bci[_cur_pos] = new_st_bci; 110 _new_end_bci[_cur_pos] = new_end_bci; 111 _cur_pos++; 112 } 113 114 int new_bci_for_old(int old_bci) { 115 if (_cur_pos == 0 || old_bci < _old_bci[0]) return old_bci; 116 _pos = 1; 117 while (_pos < _cur_pos && old_bci >= _old_bci[_pos]) 118 _pos++; 119 return _new_end_bci[_pos-1] + (old_bci - _old_bci[_pos-1]); 120 } 121 122 // Test if two indexes - one in the old method and another in the new one - correspond 123 // to the same bytecode 124 bool old_and_new_locations_same(int old_dest_bci, int new_dest_bci) { 125 if (new_bci_for_old(old_dest_bci) == new_dest_bci) 126 return true; 127 else if (_old_bci[_pos-1] == old_dest_bci) 128 return (new_dest_bci == _new_st_bci[_pos-1]); 129 else return false; 130 } 131 }; 132 133 #endif // SHARE_VM_PRIMS_METHODCOMPARATOR_HPP