1 /* 2 * Copyright (c) 2000, 2021, 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_PRIMS_METHODCOMPARATOR_HPP 26 #define SHARE_PRIMS_METHODCOMPARATOR_HPP 27 28 #include "interpreter/bytecodeStream.hpp" 29 #include "oops/constantPool.hpp" 30 #include "oops/method.hpp" 31 32 // methodComparator provides an interface for determining if methods of 33 // different versions of classes are equivalent or switchable 34 35 class MethodComparator { 36 private: 37 static bool args_same(Bytecodes::Code const c_old, Bytecodes::Code const c_new, 38 BytecodeStream* const s_old, BytecodeStream* const s_new, 39 ConstantPool* const old_cp, ConstantPool* const new_cp); 40 41 static bool pool_constants_same(const int cpi_old, const int cpi_new, 42 ConstantPool* const old_cp, ConstantPool* const new_cp); 43 44 static int check_stack_and_locals_size(Method* const old_method, Method* const new_method); 45 46 public: 47 // Check if the new method is equivalent to the old one modulo constant pool (EMCP). 48 // Intuitive definition: two versions of the same method are EMCP, if they don't differ 49 // on the source code level. Practically, we check whether the only difference between 50 // method versions is some constantpool indices embedded into the bytecodes, and whether 51 // these indices eventually point to the same constants for both method versions. 52 static bool methods_EMCP(Method* old_method, Method* new_method); 53 54 }; 55 56 #endif // SHARE_PRIMS_METHODCOMPARATOR_HPP 57