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// methodComparator provides an interface for determining if methods of 33// different versions of classes are equivalent or switchable 34 35class MethodComparator { 36 private: 37 static BytecodeStream *_s_old, *_s_new; 38 static ConstantPool* _old_cp; 39 static ConstantPool* _new_cp; 40 41 static bool args_same(Bytecodes::Code c_old, Bytecodes::Code c_new); 42 static bool pool_constants_same(int cpi_old, int cpi_new); 43 static int check_stack_and_locals_size(Method* old_method, Method* new_method); 44 45 public: 46 // Check if the new method is equivalent to the old one modulo constant pool (EMCP). 47 // Intuitive definition: two versions of the same method are EMCP, if they don't differ 48 // on the source code level. Practically, we check whether the only difference between 49 // method versions is some constantpool indices embedded into the bytecodes, and whether 50 // these indices eventually point to the same constants for both method versions. 51 static bool methods_EMCP(Method* old_method, Method* new_method); 52 53}; 54 55#endif // SHARE_VM_PRIMS_METHODCOMPARATOR_HPP 56