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Diffstat (limited to 'src/proguard/optimize/info/ReadWriteFieldMarker.java')
-rw-r--r-- | src/proguard/optimize/info/ReadWriteFieldMarker.java | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/src/proguard/optimize/info/ReadWriteFieldMarker.java b/src/proguard/optimize/info/ReadWriteFieldMarker.java new file mode 100644 index 0000000..57d8561 --- /dev/null +++ b/src/proguard/optimize/info/ReadWriteFieldMarker.java @@ -0,0 +1,163 @@ +/* + * 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.optimize.info; + +import proguard.classfile.*; +import proguard.classfile.attribute.CodeAttribute; +import proguard.classfile.constant.*; +import proguard.classfile.constant.visitor.ConstantVisitor; +import proguard.classfile.instruction.*; +import proguard.classfile.instruction.visitor.InstructionVisitor; +import proguard.classfile.util.SimplifiedVisitor; +import proguard.classfile.visitor.MemberVisitor; + +/** + * This InstructionVisitor marks all fields that are write-only. + * + * @author Eric Lafortune + */ +public class ReadWriteFieldMarker +extends SimplifiedVisitor +implements InstructionVisitor, + ConstantVisitor, + MemberVisitor +{ + // Parameters for the visitor methods. + private boolean reading = true; + private boolean writing = true; + + + // Implementations for InstructionVisitor. + + public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) {} + + + public void visitConstantInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, ConstantInstruction constantInstruction) + { + byte opcode = constantInstruction.opcode; + + // Check for instructions that involve fields. + switch (opcode) + { + case InstructionConstants.OP_LDC: + case InstructionConstants.OP_LDC_W: + // Mark the field, if any, as being read from and written to. + reading = true; + writing = true; + clazz.constantPoolEntryAccept(constantInstruction.constantIndex, this); + break; + + case InstructionConstants.OP_GETSTATIC: + case InstructionConstants.OP_GETFIELD: + // Mark the field as being read from. + reading = true; + writing = false; + clazz.constantPoolEntryAccept(constantInstruction.constantIndex, this); + break; + + case InstructionConstants.OP_PUTSTATIC: + case InstructionConstants.OP_PUTFIELD: + // Mark the field as being written to. + reading = false; + writing = true; + clazz.constantPoolEntryAccept(constantInstruction.constantIndex, this); + break; + } + } + + + // Implementations for ConstantVisitor. + + public void visitAnyConstant(Clazz clazz, Constant constant) {} + + + public void visitStringConstant(Clazz clazz, StringConstant stringConstant) + { + // Mark the referenced field, if any. + stringConstant.referencedMemberAccept(this); + } + + + public void visitFieldrefConstant(Clazz clazz, FieldrefConstant fieldrefConstant) + { + // Mark the referenced field. + fieldrefConstant.referencedMemberAccept(this); + } + + + // Implementations for MemberVisitor. + + public void visitAnyMember(Clazz Clazz, Member member) {} + + + public void visitProgramField(ProgramClass programClass, ProgramField programField) + { + // Mark the field if it is being read from. + if (reading) + { + markAsRead(programField); + } + + // Mark the field if it is being written to. + if (writing) + { + markAsWritten(programField); + } + } + + + // Small utility methods. + + private static void markAsRead(Field field) + { + FieldOptimizationInfo info = FieldOptimizationInfo.getFieldOptimizationInfo(field); + if (info != null) + { + info.setRead(); + } + } + + + public static boolean isRead(Field field) + { + FieldOptimizationInfo info = FieldOptimizationInfo.getFieldOptimizationInfo(field); + return info == null || + info.isRead(); + } + + + private static void markAsWritten(Field field) + { + FieldOptimizationInfo info = FieldOptimizationInfo.getFieldOptimizationInfo(field); + if (info != null) + { + info.setWritten(); + } + } + + + public static boolean isWritten(Field field) + { + FieldOptimizationInfo info = FieldOptimizationInfo.getFieldOptimizationInfo(field); + return info == null || + info.isWritten(); + } +} |