1/* 2 * ProGuard -- shrinking, optimization, obfuscation, and preverification 3 * of Java bytecode. 4 * 5 * Copyright (c) 2002-2014 Eric Lafortune (eric@graphics.cornell.edu) 6 * 7 * This program is free software; you can redistribute it and/or modify it 8 * under the terms of the GNU General Public License as published by the Free 9 * Software Foundation; either version 2 of the License, or (at your option) 10 * any later version. 11 * 12 * This program is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15 * more details. 16 * 17 * You should have received a copy of the GNU General Public License along 18 * with this program; if not, write to the Free Software Foundation, Inc., 19 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21package proguard.optimize; 22 23import proguard.classfile.*; 24import proguard.classfile.attribute.BootstrapMethodInfo; 25import proguard.classfile.attribute.visitor.BootstrapMethodInfoVisitor; 26import proguard.classfile.constant.*; 27import proguard.classfile.constant.visitor.ConstantVisitor; 28import proguard.classfile.util.SimplifiedVisitor; 29import proguard.classfile.visitor.MemberVisitor; 30import proguard.optimize.info.*; 31import proguard.optimize.peephole.VariableShrinker; 32 33/** 34 * This BootstrapMethodInfoVisitor removes unused constant arguments from 35 * bootstrap method entries that it visits. 36 * 37 * @see ParameterUsageMarker 38 * @see VariableUsageMarker 39 * @see VariableShrinker 40 * @author Eric Lafortune 41 */ 42public class BootstrapMethodArgumentShrinker 43extends SimplifiedVisitor 44implements BootstrapMethodInfoVisitor, 45 ConstantVisitor, 46 MemberVisitor 47{ 48 private long usedParameters; 49 50 51 // Implementations for BootstrapMethodInfoVisitor. 52 53 public void visitBootstrapMethodInfo(Clazz clazz, BootstrapMethodInfo bootstrapMethodInfo) 54 { 55 // Check which method parameters are used. 56 usedParameters = -1L; 57 clazz.constantPoolEntryAccept(bootstrapMethodInfo.u2methodHandleIndex, this); 58 59 // Remove the unused arguments. 60 int methodArgumentCount = bootstrapMethodInfo.u2methodArgumentCount; 61 int[] methodArguments = bootstrapMethodInfo.u2methodArguments; 62 63 int newArgumentIndex = 0; 64 65 for (int argumentIndex = 0; argumentIndex < methodArgumentCount; argumentIndex++) 66 { 67 if (argumentIndex >= 64 || 68 (usedParameters & (1L << argumentIndex)) != 0L) 69 { 70 methodArguments[newArgumentIndex++] = methodArguments[argumentIndex]; 71 } 72 } 73 74 // Update the number of arguments. 75 bootstrapMethodInfo.u2methodArgumentCount = newArgumentIndex; 76 } 77 78 79 // Implementations for ConstantVisitor. 80 81 public void visitMethodHandleConstant(Clazz clazz, MethodHandleConstant methodHandleConstant) 82 { 83 // Check the referenced bootstrap method. 84 clazz.constantPoolEntryAccept(methodHandleConstant.u2referenceIndex, this); 85 } 86 87 88 public void visitAnyRefConstant(Clazz clazz, RefConstant refConstant) 89 { 90 // Check the referenced class member itself. 91 refConstant.referencedMemberAccept(this); 92 } 93 94 95 // Implementations for MemberVisitor. 96 97 public void visitLibraryMethod(LibraryClass libraryClass, LibraryMethod libraryMethod) {} 98 99 100 public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod) 101 { 102 usedParameters = ParameterUsageMarker.getUsedParameters(programMethod); 103 } 104} 105