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ProGuardCORE is a free library to read, analyze, modify, and write Java class files.
/*
* ProGuardCORE -- library to process Java bytecode.
*
* Copyright (c) 2002-2020 Guardsquare NV
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package proguard.evaluation;
import proguard.classfile.*;
import proguard.classfile.attribute.CodeAttribute;
import proguard.classfile.instruction.*;
import proguard.classfile.instruction.visitor.InstructionVisitor;
import proguard.evaluation.value.*;
/**
* This {@link ValueFactory} tags newly created reference values so they can be traced
* throughout the execution of a method.
*
* @see TracedReferenceValue
* @see InstructionOffsetValue
* @author Eric Lafortune
*/
public class ReferenceTracingValueFactory
implements InstructionVisitor,
ValueFactory
{
private final ValueFactory valueFactory;
private final boolean preserveTraceValueOnCasts;
private Value traceValue;
/**
* Creates a new ReferenceTracingValueFactory that attaches instruction
* offset values based on being used as an instruction visitor. This
* instance preserves trace values in the {@link #cast} method.
* @param valueFactory the value factory that creates the actual values.
*/
public ReferenceTracingValueFactory(ValueFactory valueFactory)
{
this(valueFactory, true);
}
/**
* Creates a new ReferenceTracingValueFactory that attaches instruction
* offset values based on being used as an instruction visitor.
* @param valueFactory the value factory that creates the
* actual values.
* @param preserveTraceValueOnCasts specifies whether to preserve the
* trace value for reference values that
* are passed to the {@link #cast} method.
*/
public ReferenceTracingValueFactory(ValueFactory valueFactory,
boolean preserveTraceValueOnCasts)
{
this.valueFactory = valueFactory;
this.preserveTraceValueOnCasts = preserveTraceValueOnCasts;
}
public void setTraceValue(Value traceValue)
{
this.traceValue = traceValue;
}
/**
* Casts a given traced reference value to the given type, either keeping
* its trace value or setting a new one.
*/
public TracedReferenceValue cast(TracedReferenceValue referenceValue,
String type,
Clazz referencedClass,
boolean alwaysCast)
{
// Cast the value.
ReferenceValue castValue =
referenceValue.getReferenceValue().cast(type,
referencedClass,
valueFactory,
alwaysCast);
// Trace it.
return new TracedReferenceValue(castValue,
preserveTraceValueOnCasts ?
referenceValue.getTraceValue() :
traceValue);
}
// Implementations for InstructionVisitor.
public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction)
{
traceValue = null;
}
public void visitSimpleInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, SimpleInstruction simpleInstruction)
{
switch (simpleInstruction.opcode)
{
case Instruction.OP_ACONST_NULL:
case Instruction.OP_NEWARRAY:
case Instruction.OP_ATHROW:
traceValue = new InstructionOffsetValue(offset | InstructionOffsetValue.NEW_INSTANCE);
break;
case Instruction.OP_AALOAD:
traceValue = new InstructionOffsetValue(offset);
break;
default:
traceValue = null;
break;
}
}
public void visitConstantInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, ConstantInstruction constantInstruction)
{
switch (constantInstruction.opcode)
{
case Instruction.OP_LDC:
case Instruction.OP_LDC_W:
case Instruction.OP_NEW:
case Instruction.OP_ANEWARRAY:
case Instruction.OP_MULTIANEWARRAY:
traceValue = new InstructionOffsetValue(offset | InstructionOffsetValue.NEW_INSTANCE);
break;
case Instruction.OP_GETSTATIC:
case Instruction.OP_GETFIELD:
traceValue = new InstructionOffsetValue(offset | InstructionOffsetValue.FIELD_VALUE);
break;
case Instruction.OP_INVOKEVIRTUAL:
case Instruction.OP_INVOKESPECIAL:
case Instruction.OP_INVOKESTATIC:
case Instruction.OP_INVOKEINTERFACE:
traceValue = new InstructionOffsetValue(offset | InstructionOffsetValue.METHOD_RETURN_VALUE);
break;
case Instruction.OP_CHECKCAST:
traceValue = new InstructionOffsetValue(offset | InstructionOffsetValue.CAST);
break;
default:
traceValue = null;
break;
}
}
// Implementations for BasicValueFactory.
public Value createValue(String type,
Clazz referencedClass,
boolean mayBeExtension,
boolean mayBeNull)
{
return trace(valueFactory.createValue(type,
referencedClass,
mayBeExtension,
mayBeNull));
}
public IntegerValue createIntegerValue()
{
return valueFactory.createIntegerValue();
}
public IntegerValue createIntegerValue(int value)
{
return valueFactory.createIntegerValue(value);
}
public IntegerValue createIntegerValue(int min, int max)
{
return valueFactory.createIntegerValue(min, max);
}
public LongValue createLongValue()
{
return valueFactory.createLongValue();
}
public LongValue createLongValue(long value)
{
return valueFactory.createLongValue(value);
}
public FloatValue createFloatValue()
{
return valueFactory.createFloatValue();
}
public FloatValue createFloatValue(float value)
{
return valueFactory.createFloatValue(value);
}
public DoubleValue createDoubleValue()
{
return valueFactory.createDoubleValue();
}
public DoubleValue createDoubleValue(double value)
{
return valueFactory.createDoubleValue(value);
}
public ReferenceValue createReferenceValue()
{
return trace(valueFactory.createReferenceValue());
}
public ReferenceValue createReferenceValueNull()
{
return trace(valueFactory.createReferenceValueNull());
}
public ReferenceValue createReferenceValue(String type,
Clazz referencedClass,
boolean mayBeExtension,
boolean mayBeNull)
{
return trace(valueFactory.createReferenceValue(type,
referencedClass,
mayBeExtension,
mayBeNull));
}
public ReferenceValue createReferenceValue(String type,
Clazz referencedClass,
boolean mayBeExtension,
boolean mayBeNull,
Object value)
{
return trace(valueFactory.createReferenceValue(type,
referencedClass,
mayBeExtension,
mayBeNull,
value
));
}
public ReferenceValue createArrayReferenceValue(String type,
Clazz referencedClass,
IntegerValue arrayLength)
{
return trace(valueFactory.createArrayReferenceValue(type, referencedClass, arrayLength));
}
/**
* Creates a new ReferenceValue that represents an array with elements of
* the given type, with the given length and initial element values.
*/
public ReferenceValue createArrayReferenceValue(String type,
Clazz referencedClass,
IntegerValue arrayLength,
Value elementValue)
{
return trace(valueFactory.createArrayReferenceValue(type, referencedClass, arrayLength, elementValue));
}
// Small utility methods.
/**
* Attaches the current trace value to given value, if it is a reference
* value.
*/
public Value trace(Value value)
{
return value.computationalType() == Value.TYPE_REFERENCE ?
trace(value.referenceValue()) :
value;
}
/**
* Attaches the current trace value to given reference value.
*/
public ReferenceValue trace(ReferenceValue referenceValue)
{
return traceValue != null ?
new TracedReferenceValue(referenceValue, traceValue) :
referenceValue;
}
}
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