1 /*
   2  * Copyright (c) 2013, 2018, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.jfr.internal.instrument;
  27 
  28 import java.lang.reflect.Method;
  29 import java.util.HashMap;
  30 import java.util.List;
  31 import java.util.Map;
  32 
  33 import jdk.internal.org.objectweb.asm.ClassVisitor;
  34 import jdk.internal.org.objectweb.asm.MethodVisitor;
  35 import jdk.internal.org.objectweb.asm.Opcodes;
  36 import jdk.internal.org.objectweb.asm.Type;
  37 import jdk.internal.org.objectweb.asm.commons.RemappingMethodAdapter;
  38 import jdk.internal.org.objectweb.asm.commons.SimpleRemapper;
  39 import jdk.internal.org.objectweb.asm.tree.ClassNode;
  40 import jdk.internal.org.objectweb.asm.tree.MethodNode;
  41 import jdk.jfr.internal.LogLevel;
  42 import jdk.jfr.internal.LogTag;
  43 import jdk.jfr.internal.Logger;
  44 
  45 /**
  46  * This class will merge (some) methods from one class into another one.
  47  *
  48  * @author Staffan Larsen
  49  */
  50 @Deprecated
  51 final class JIMethodMergeAdapter extends ClassVisitor {
  52 
  53     private final ClassNode cn;
  54     private final List<Method> methodFilter;
  55     private final Map<String, String> typeMap;
  56 
  57     /**
  58      * Methods in methodFilter that exist in cn will be merged into cv. If the method already exists,
  59      * the original method will be deleted.
  60      *
  61      * @param cv
  62      * @param cn - a ClassNode with Methods that will be merged into this class
  63      * @param methodFilter - only methods in this list will be merged
  64      * @param typeMappings - while merging, type references in the methods will be changed according to this map
  65      */
  66     public JIMethodMergeAdapter(ClassVisitor cv, ClassNode cn, List<Method> methodFilter, JITypeMapping[] typeMappings) {
  67         super(Opcodes.ASM7, cv);
  68         this.cn = cn;
  69         this.methodFilter = methodFilter;
  70 
  71         this.typeMap = new HashMap<>();
  72         for (JITypeMapping tm : typeMappings) {
  73             typeMap.put(tm.from().replace('.', '/'), tm.to().replace('.', '/'));
  74         }
  75     }
  76 
  77     @Override
  78     public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) {
  79         super.visit(version, access, name, signature, superName, interfaces);
  80         typeMap.put(cn.name, name);
  81     }
  82 
  83     @Override
  84     public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
  85         if(methodInFilter(name, desc)) {
  86             // If the method is one that we will be replacing, delete the method
  87             Logger.log(LogTag.JFR_SYSTEM_BYTECODE, LogLevel.DEBUG, "Deleting " + name + desc);
  88             return null;
  89         }
  90         return super.visitMethod(access, name, desc, signature, exceptions);
  91     }
  92 
  93     @Override
  94     public void visitEnd() {
  95         SimpleRemapper remapper = new SimpleRemapper(typeMap);
  96         for (MethodNode mn : cn.methods) {
  97             // Check if the method is in the list of methods to copy
  98             if (methodInFilter(mn.name, mn.desc)) {
  99                 Logger.log(LogTag.JFR_SYSTEM_BYTECODE, LogLevel.DEBUG, "Copying method: " + mn.name + mn.desc);
 100                 Logger.log(LogTag.JFR_SYSTEM_BYTECODE, LogLevel.DEBUG,  "   with mapper: " + typeMap);
 101 
 102                 String[] exceptions = new String[mn.exceptions.size()];
 103                 mn.exceptions.toArray(exceptions);
 104                 MethodVisitor mv = cv.visitMethod(mn.access, mn.name, mn.desc, mn.signature, exceptions);
 105                 mn.instructions.resetLabels();
 106                 mn.accept(new RemappingMethodAdapter(mn.access, mn.desc, mv, remapper));
 107             }
 108         }
 109         super.visitEnd();
 110     }
 111 
 112     private boolean methodInFilter(String name, String desc) {
 113         for(Method m : methodFilter) {
 114             if (m.getName().equals(name) && Type.getMethodDescriptor(m).equals(desc)) {
 115                 return true;
 116             }
 117         }
 118         return false;
 119     }
 120 }