1 /* 2 * Copyright (c) 2000, 2010, 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/constantPoolOop.hpp" 30 #include "oops/methodOop.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 constantPoolOop _old_cp, _new_cp; 41 static BciMap *_bci_map; 42 static bool _switchable_test; 43 static GrowableArray<int> *_fwd_jmps; 44 45 static bool args_same(Bytecodes::Code c_old, Bytecodes::Code c_new); 46 static int check_stack_and_locals_size(methodOop old_method, methodOop new_method); 47 48 public: 49 // Check if the new method is equivalent to the old one modulo constant pool (EMCP). 50 // Intuitive definition: two versions of the same method are EMCP, if they don't differ 51 // on the source code level. Practically, we check whether the only difference between 52 // method versions is some constantpool indices embedded into the bytecodes, and whether 53 // these indices eventually point to the same constants for both method versions. 54 static bool methods_EMCP(methodOop old_method, methodOop new_method); 55 56 static bool methods_switchable(methodOop old_method, methodOop new_method, BciMap &bci_map); 57 }; 58 59 60 // ByteCode Index Map. For two versions of the same method, where the new version may contain 61 // fragments not found in the old version, provides a mapping from an index of a bytecode in 62 // the old method to the index of the same bytecode in the new method. 63 64 class BciMap { 65 private: 66 int *_old_bci, *_new_st_bci, *_new_end_bci; 67 int _cur_size, _cur_pos; 68 int _pos; 69 70 public: 71 BciMap() { 72 _cur_size = 50; 73 _old_bci = (int*) malloc(sizeof(int) * _cur_size); 74 _new_st_bci = (int*) malloc(sizeof(int) * _cur_size); 75 _new_end_bci = (int*) malloc(sizeof(int) * _cur_size); 76 _cur_pos = 0; 77 } 78 79 ~BciMap() { 80 free(_old_bci); 81 free(_new_st_bci); 82 free(_new_end_bci); 83 } 84 85 // Store the position of an added fragment, e.g. 86 // 87 // |<- old_bci 88 // ----------------------------------------- 89 // Old method |invokevirtual 5|aload 1|... 90 // ----------------------------------------- 91 // 92 // |<- new_st_bci |<- new_end_bci 93 // -------------------------------------------------------------------- 94 // New method |invokevirual 5|aload 2|invokevirtual 6|aload 1|... 95 // -------------------------------------------------------------------- 96 // ^^^^^^^^^^^^^^^^^^^^^^^^ 97 // Added fragment 98 99 void store_fragment_location(int old_bci, int new_st_bci, int new_end_bci) { 100 if (_cur_pos == _cur_size) { 101 _cur_size += 10; 102 _old_bci = (int*) realloc(_old_bci, sizeof(int) * _cur_size); 103 _new_st_bci = (int*) realloc(_new_st_bci, sizeof(int) * _cur_size); 104 _new_end_bci = (int*) realloc(_new_end_bci, sizeof(int) * _cur_size); 105 } 106 _old_bci[_cur_pos] = old_bci; 107 _new_st_bci[_cur_pos] = new_st_bci; 108 _new_end_bci[_cur_pos] = new_end_bci; 109 _cur_pos++; 110 } 111 112 int new_bci_for_old(int old_bci) { 113 if (_cur_pos == 0 || old_bci < _old_bci[0]) return old_bci; 114 _pos = 1; 115 while (_pos < _cur_pos && old_bci >= _old_bci[_pos]) 116 _pos++; 117 return _new_end_bci[_pos-1] + (old_bci - _old_bci[_pos-1]); 118 } 119 120 // Test if two indexes - one in the old method and another in the new one - correspond 121 // to the same bytecode 122 bool old_and_new_locations_same(int old_dest_bci, int new_dest_bci) { 123 if (new_bci_for_old(old_dest_bci) == new_dest_bci) 124 return true; 125 else if (_old_bci[_pos-1] == old_dest_bci) 126 return (new_dest_bci == _new_st_bci[_pos-1]); 127 else return false; 128 } 129 }; 130 131 #endif // SHARE_VM_PRIMS_METHODCOMPARATOR_HPP