1 /* 2 * Copyright (c) 2000, 2016, 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 GrowableArray<int> *_fwd_jmps; 44 45 static bool args_same(Bytecodes::Code c_old, Bytecodes::Code c_new); 46 static bool pool_constants_same(int cpi_old, int cpi_new); 47 static int check_stack_and_locals_size(Method* old_method, Method* new_method); 48 49 public: 50 // Check if the new method is equivalent to the old one modulo constant pool (EMCP). 51 // Intuitive definition: two versions of the same method are EMCP, if they don't differ 52 // on the source code level. Practically, we check whether the only difference between 53 // method versions is some constantpool indices embedded into the bytecodes, and whether 54 // these indices eventually point to the same constants for both method versions. 55 static bool methods_EMCP(Method* old_method, Method* new_method); 56 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 int new_bci_for_old(int old_bci) { 86 if (_cur_pos == 0 || old_bci < _old_bci[0]) return old_bci; 87 _pos = 1; 88 while (_pos < _cur_pos && old_bci >= _old_bci[_pos]) 89 _pos++; 90 return _new_end_bci[_pos-1] + (old_bci - _old_bci[_pos-1]); 91 } 92 93 // Test if two indexes - one in the old method and another in the new one - correspond 94 // to the same bytecode 95 bool old_and_new_locations_same(int old_dest_bci, int new_dest_bci) { 96 if (new_bci_for_old(old_dest_bci) == new_dest_bci) 97 return true; 98 else if (_old_bci[_pos-1] == old_dest_bci) 99 return (new_dest_bci == _new_st_bci[_pos-1]); 100 else return false; 101 } 102 }; 103 104 #endif // SHARE_VM_PRIMS_METHODCOMPARATOR_HPP