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/*
* ProGuard -- shrinking, optimization, obfuscation, and preverification
* of Java bytecode.
*
* Copyright (c) 2002-2014 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.*;
import proguard.classfile.attribute.visitor.*;
import proguard.classfile.util.SimplifiedVisitor;
import proguard.evaluation.ConstantValueFactory;
import proguard.evaluation.value.*;
/**
* This class stores some optimization information that can be attached to
* a field.
*
* @author Eric Lafortune
*/
public class FieldOptimizationInfo
extends SimplifiedVisitor
implements AttributeVisitor
{
private static final ParticularValueFactory VALUE_FACTORY = new ParticularValueFactory();
private static final ConstantValueFactory CONSTANT_VALUE_FACTORY = new ConstantValueFactory(VALUE_FACTORY);
private static final InitialValueFactory INITIAL_VALUE_FACTORY = new InitialValueFactory(VALUE_FACTORY);
private boolean isWritten;
private boolean isRead;
private boolean canBeMadePrivate = true;
private ReferenceValue referencedClass;
private Value value;
public FieldOptimizationInfo(Clazz clazz, Field field)
{
int accessFlags = field.getAccessFlags();
isWritten =
isRead = (accessFlags & ClassConstants.ACC_VOLATILE) != 0;
resetValue(clazz, field);
}
public FieldOptimizationInfo(FieldOptimizationInfo FieldOptimizationInfo)
{
this.isWritten = FieldOptimizationInfo.isWritten;
this.isRead = FieldOptimizationInfo.isRead;
this.canBeMadePrivate = FieldOptimizationInfo.canBeMadePrivate;
this.referencedClass = FieldOptimizationInfo.referencedClass;
this.value = FieldOptimizationInfo.value;
}
public void setWritten()
{
isWritten = true;
}
public boolean isWritten()
{
return isWritten;
}
public void setRead()
{
isRead = true;
}
public boolean isRead()
{
return isRead;
}
public void setCanNotBeMadePrivate()
{
canBeMadePrivate = false;
}
public boolean canBeMadePrivate()
{
return canBeMadePrivate;
}
public void generalizeReferencedClass(ReferenceValue referencedClass)
{
this.referencedClass = this.referencedClass != null ?
this.referencedClass.generalize(referencedClass) :
referencedClass;
}
public ReferenceValue getReferencedClass()
{
return referencedClass;
}
public void resetValue(Clazz clazz, Field field)
{
int accessFlags = field.getAccessFlags();
value = null;
// See if we can initialize a static field with a constant value.
if ((accessFlags & ClassConstants.ACC_STATIC) != 0)
{
field.accept(clazz, new AllAttributeVisitor(this));
}
// Otherwise initialize a non-final field with the default value.
// Conservatively, even a final field needs to be initialized with the
// default value, because it may be accessed before it is set.
if (value == null &&
(SideEffectInstructionChecker.OPTIMIZE_CONSERVATIVELY ||
(accessFlags & ClassConstants.ACC_FINAL) == 0))
{
value = INITIAL_VALUE_FACTORY.createValue(field.getDescriptor(clazz));
}
}
public void generalizeValue(Value value)
{
this.value = this.value != null ?
this.value.generalize(value) :
value;
}
public Value getValue()
{
return value;
}
// Implementations for AttributeVisitor.
public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
public void visitConstantValueAttribute(Clazz clazz, Field field, ConstantValueAttribute constantValueAttribute)
{
// Retrieve the initial static field value.
value = CONSTANT_VALUE_FACTORY.constantValue(clazz, constantValueAttribute.u2constantValueIndex);
}
// Small utility methods.
public static void setFieldOptimizationInfo(Clazz clazz, Field field)
{
field.setVisitorInfo(new FieldOptimizationInfo(clazz, field));
}
public static FieldOptimizationInfo getFieldOptimizationInfo(Field field)
{
Object visitorInfo = field.getVisitorInfo();
return visitorInfo instanceof FieldOptimizationInfo ?
(FieldOptimizationInfo)visitorInfo :
null;
}
}
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