| /* |
| * ProGuard -- shrinking, optimization, obfuscation, and preverification |
| * of Java bytecode. |
| * |
| * Copyright (c) 2002-2009 Eric Lafortune (eric@graphics.cornell.edu) |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License as published by the Free |
| * Software Foundation; either version 2 of the License, or (at your option) |
| * any later version. |
| * |
| * This program is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| * more details. |
| * |
| * You should have received a copy of the GNU General Public License along |
| * with this program; if not, write to the Free Software Foundation, Inc., |
| * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| package proguard.shrink; |
| |
| import proguard.classfile.*; |
| import proguard.classfile.attribute.*; |
| import proguard.classfile.attribute.annotation.*; |
| import proguard.classfile.attribute.annotation.visitor.*; |
| import proguard.classfile.attribute.visitor.AttributeVisitor; |
| import proguard.classfile.constant.*; |
| import proguard.classfile.editor.*; |
| import proguard.classfile.util.*; |
| import proguard.classfile.visitor.*; |
| |
| /** |
| * This ClassVisitor removes constant pool entries and class members that |
| * are not marked as being used. |
| * |
| * @see UsageMarker |
| * |
| * @author Eric Lafortune |
| */ |
| public class ClassShrinker |
| extends SimplifiedVisitor |
| implements ClassVisitor, |
| MemberVisitor, |
| AttributeVisitor, |
| AnnotationVisitor, |
| ElementValueVisitor |
| { |
| private final UsageMarker usageMarker; |
| |
| private int[] constantIndexMap = new int[ClassConstants.TYPICAL_CONSTANT_POOL_SIZE]; |
| |
| private final ConstantPoolRemapper constantPoolRemapper = new ConstantPoolRemapper(); |
| |
| |
| /** |
| * Creates a new ClassShrinker. |
| * @param usageMarker the usage marker that is used to mark the classes |
| * and class members. |
| */ |
| public ClassShrinker(UsageMarker usageMarker) |
| { |
| this.usageMarker = usageMarker; |
| } |
| |
| |
| // Implementations for ClassVisitor. |
| |
| public void visitProgramClass(ProgramClass programClass) |
| { |
| // Shrink the arrays for constant pool, interfaces, fields, methods, |
| // and class attributes. |
| programClass.u2interfacesCount = |
| shrinkConstantIndexArray(programClass.constantPool, |
| programClass.u2interfaces, |
| programClass.u2interfacesCount); |
| |
| // Shrinking the constant pool also sets up an index map. |
| programClass.u2constantPoolCount = |
| shrinkConstantPool(programClass.constantPool, |
| programClass.u2constantPoolCount); |
| |
| programClass.u2fieldsCount = |
| shrinkArray(programClass.fields, |
| programClass.u2fieldsCount); |
| |
| programClass.u2methodsCount = |
| shrinkArray(programClass.methods, |
| programClass.u2methodsCount); |
| |
| programClass.u2attributesCount = |
| shrinkArray(programClass.attributes, |
| programClass.u2attributesCount); |
| |
| // Compact the remaining fields, methods, and attributes, |
| // and remap their references to the constant pool. |
| programClass.fieldsAccept(this); |
| programClass.methodsAccept(this); |
| programClass.attributesAccept(this); |
| |
| // Remap all constant pool references. |
| constantPoolRemapper.setConstantIndexMap(constantIndexMap); |
| constantPoolRemapper.visitProgramClass(programClass); |
| |
| // Remove the unused interfaces from the class signature. |
| programClass.attributesAccept(new SignatureShrinker()); |
| |
| // Compact the extra field pointing to the subclasses of this class. |
| programClass.subClasses = |
| shrinkToNewArray(programClass.subClasses); |
| } |
| |
| |
| public void visitLibraryClass(LibraryClass libraryClass) |
| { |
| // Library classes are left unchanged. |
| |
| // Compact the extra field pointing to the subclasses of this class. |
| libraryClass.subClasses = |
| shrinkToNewArray(libraryClass.subClasses); |
| } |
| |
| |
| // Implementations for MemberVisitor. |
| |
| public void visitProgramMember(ProgramClass programClass, ProgramMember programMember) |
| { |
| // Shrink the attributes array. |
| programMember.u2attributesCount = |
| shrinkArray(programMember.attributes, |
| programMember.u2attributesCount); |
| |
| // Shrink any attributes. |
| programMember.attributesAccept(programClass, this); |
| } |
| |
| |
| // Implementations for AttributeVisitor. |
| |
| public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} |
| |
| |
| public void visitInnerClassesAttribute(Clazz clazz, InnerClassesAttribute innerClassesAttribute) |
| { |
| // Shrink the array of InnerClassesInfo objects. |
| innerClassesAttribute.u2classesCount = |
| shrinkArray(innerClassesAttribute.classes, |
| innerClassesAttribute.u2classesCount); |
| } |
| |
| |
| public void visitEnclosingMethodAttribute(Clazz clazz, EnclosingMethodAttribute enclosingMethodAttribute) |
| { |
| // Sometimes, a class is still referenced (apparently as a dummy class), |
| // but its enclosing method is not. Then remove the reference to |
| // the enclosing method. |
| // E.g. the anonymous inner class javax.swing.JList$1 is defined inside |
| // a constructor of javax.swing.JList, but it is also referenced as a |
| // dummy argument in a constructor of javax.swing.JList$ListSelectionHandler. |
| if (enclosingMethodAttribute.referencedMethod != null && |
| !usageMarker.isUsed(enclosingMethodAttribute.referencedMethod)) |
| { |
| enclosingMethodAttribute.u2nameAndTypeIndex = 0; |
| |
| enclosingMethodAttribute.referencedMethod = null; |
| } |
| } |
| |
| |
| public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute) |
| { |
| // Shrink the attributes array. |
| codeAttribute.u2attributesCount = |
| shrinkArray(codeAttribute.attributes, |
| codeAttribute.u2attributesCount); |
| } |
| |
| |
| public void visitAnyAnnotationsAttribute(Clazz clazz, AnnotationsAttribute annotationsAttribute) |
| { |
| // Shrink the annotations array. |
| annotationsAttribute.u2annotationsCount = |
| shrinkArray(annotationsAttribute.annotations, |
| annotationsAttribute.u2annotationsCount); |
| |
| // Shrink the annotations themselves. |
| annotationsAttribute.annotationsAccept(clazz, this); |
| } |
| |
| |
| public void visitAnyParameterAnnotationsAttribute(Clazz clazz, Method method, ParameterAnnotationsAttribute parameterAnnotationsAttribute) |
| { |
| // Loop over all parameters. |
| for (int parameterIndex = 0; parameterIndex < parameterAnnotationsAttribute.u2parametersCount; parameterIndex++) |
| { |
| // Shrink the parameter annotations array. |
| parameterAnnotationsAttribute.u2parameterAnnotationsCount[parameterIndex] = |
| shrinkArray(parameterAnnotationsAttribute.parameterAnnotations[parameterIndex], |
| parameterAnnotationsAttribute.u2parameterAnnotationsCount[parameterIndex]); |
| } |
| |
| // Shrink the annotations themselves. |
| parameterAnnotationsAttribute.annotationsAccept(clazz, method, this); |
| } |
| |
| |
| // Implementations for AnnotationVisitor. |
| |
| public void visitAnnotation(Clazz clazz, Annotation annotation) |
| { |
| // Shrink the element values array. |
| annotation.u2elementValuesCount = |
| shrinkArray(annotation.elementValues, |
| annotation.u2elementValuesCount); |
| |
| // Shrink the element values themselves. |
| annotation.elementValuesAccept(clazz, this); |
| } |
| |
| |
| /** |
| * This AttributeVisitor updates the Utf8 constants of class signatures, |
| * removing any unused interfaces. |
| */ |
| private class SignatureShrinker |
| extends SimplifiedVisitor |
| implements AttributeVisitor |
| { |
| public void visitAnyAttribute(Clazz clazz, Attribute attribute) {} |
| |
| |
| public void visitSignatureAttribute(Clazz clazz, SignatureAttribute signatureAttribute) |
| { |
| Clazz[] referencedClasses = signatureAttribute.referencedClasses; |
| if (referencedClasses != null) |
| { |
| // Go over the generic definitions, superclass and implemented interfaces. |
| String signature = clazz.getString(signatureAttribute.u2signatureIndex); |
| |
| InternalTypeEnumeration internalTypeEnumeration = |
| new InternalTypeEnumeration(signature); |
| |
| StringBuffer newSignatureBuffer = new StringBuffer(); |
| |
| int referencedClassIndex = 0; |
| int newReferencedClassIndex = 0; |
| |
| while (internalTypeEnumeration.hasMoreTypes()) |
| { |
| // Consider the classes referenced by this signature. |
| String type = internalTypeEnumeration.nextType(); |
| int classCount = new DescriptorClassEnumeration(type).classCount(); |
| |
| Clazz referencedClass = referencedClasses[referencedClassIndex]; |
| if (referencedClass == null || |
| usageMarker.isUsed(referencedClass)) |
| { |
| // Append the superclass or interface. |
| newSignatureBuffer.append(type); |
| |
| // Copy the referenced classes. |
| for (int counter = 0; counter < classCount; counter++) |
| { |
| referencedClasses[newReferencedClassIndex++] = |
| referencedClasses[referencedClassIndex++]; |
| } |
| } |
| else |
| { |
| // Skip the referenced classes. |
| referencedClassIndex += classCount; |
| } |
| } |
| |
| if (newReferencedClassIndex < referencedClassIndex) |
| { |
| // Update the signature. |
| ((Utf8Constant)((ProgramClass)clazz).constantPool[signatureAttribute.u2signatureIndex]).setString(newSignatureBuffer.toString()); |
| |
| // Clear the unused entries. |
| while (newReferencedClassIndex < referencedClassIndex) |
| { |
| referencedClasses[newReferencedClassIndex++] = null; |
| } |
| } |
| } |
| } |
| } |
| |
| |
| // Implementations for ElementValueVisitor. |
| |
| public void visitAnyElementValue(Clazz clazz, Annotation annotation, ElementValue elementValue) {} |
| |
| |
| public void visitAnnotationElementValue(Clazz clazz, Annotation annotation, AnnotationElementValue annotationElementValue) |
| { |
| // Shrink the contained annotation. |
| annotationElementValue.annotationAccept(clazz, this); |
| } |
| |
| |
| public void visitArrayElementValue(Clazz clazz, Annotation annotation, ArrayElementValue arrayElementValue) |
| { |
| // Shrink the element values array. |
| arrayElementValue.u2elementValuesCount = |
| shrinkArray(arrayElementValue.elementValues, |
| arrayElementValue.u2elementValuesCount); |
| |
| // Shrink the element values themselves. |
| arrayElementValue.elementValuesAccept(clazz, annotation, this); |
| } |
| |
| |
| // Small utility methods. |
| |
| /** |
| * Removes all entries that are not marked as being used from the given |
| * constant pool. |
| * @return the new number of entries. |
| */ |
| private int shrinkConstantPool(Constant[] constantPool, int length) |
| { |
| if (constantIndexMap.length < length) |
| { |
| constantIndexMap = new int[length]; |
| } |
| |
| int counter = 1; |
| boolean isUsed = false; |
| |
| // Shift the used constant pool entries together. |
| for (int index = 1; index < length; index++) |
| { |
| constantIndexMap[index] = counter; |
| |
| Constant constant = constantPool[index]; |
| |
| // Don't update the flag if this is the second half of a long entry. |
| if (constant != null) |
| { |
| isUsed = usageMarker.isUsed(constant); |
| } |
| |
| if (isUsed) |
| { |
| constantPool[counter++] = constant; |
| } |
| } |
| |
| // Clear the remaining constant pool elements. |
| for (int index = counter; index < length; index++) |
| { |
| constantPool[index] = null; |
| } |
| |
| return counter; |
| } |
| |
| |
| /** |
| * Removes all indices that point to unused constant pool entries |
| * from the given array. |
| * @return the new number of indices. |
| */ |
| private int shrinkConstantIndexArray(Constant[] constantPool, int[] array, int length) |
| { |
| int counter = 0; |
| |
| // Shift the used objects together. |
| for (int index = 0; index < length; index++) |
| { |
| if (usageMarker.isUsed(constantPool[array[index]])) |
| { |
| array[counter++] = array[index]; |
| } |
| } |
| |
| // Clear the remaining array elements. |
| for (int index = counter; index < length; index++) |
| { |
| array[index] = 0; |
| } |
| |
| return counter; |
| } |
| |
| |
| /** |
| * Removes all Clazz objects that are not marked as being used |
| * from the given array and returns the remaining objects in a an array |
| * of the right size. |
| * @return the new array. |
| */ |
| private Clazz[] shrinkToNewArray(Clazz[] array) |
| { |
| if (array == null) |
| { |
| return null; |
| } |
| |
| // Shrink the given array in-place. |
| int length = shrinkArray(array, array.length); |
| if (length == 0) |
| { |
| return null; |
| } |
| |
| // Return immediately if the array is of right size already. |
| if (length == array.length) |
| { |
| return array; |
| } |
| |
| // Copy the remaining elements into a new array of the right size. |
| Clazz[] newArray = new Clazz[length]; |
| System.arraycopy(array, 0, newArray, 0, length); |
| return newArray; |
| } |
| |
| |
| /** |
| * Removes all VisitorAccepter objects that are not marked as being used |
| * from the given array. |
| * @return the new number of VisitorAccepter objects. |
| */ |
| private int shrinkArray(VisitorAccepter[] array, int length) |
| { |
| int counter = 0; |
| |
| // Shift the used objects together. |
| for (int index = 0; index < length; index++) |
| { |
| if (usageMarker.isUsed(array[index])) |
| { |
| array[counter++] = array[index]; |
| } |
| } |
| |
| // Clear the remaining array elements. |
| for (int index = counter; index < length; index++) |
| { |
| array[index] = null; |
| } |
| |
| return counter; |
| } |
| } |
