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diff --git a/src/proguard/evaluation/TracedVariables.java b/src/proguard/evaluation/TracedVariables.java
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+++ b/src/proguard/evaluation/TracedVariables.java
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+/*
+ * 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.evaluation;
+
+import proguard.evaluation.value.Value;
+
+/**
+ * This Variables class saves additional information with variables, to keep
+ * track of their origins.
+ * <p>
+ * The Variables class stores a given producer Value along with each Value it
+ * stores. It then generalizes a given collected Value with the producer Value
+ * of each Value it loads. The producer Value and the initial collected Value
+ * can be set; the generalized collected Value can be retrieved.
+ * <p>
+ * In addition, an initialization index can be reset and retrieved, pointing
+ * to the most recent variable that has been initialized by a store operation.
+ *
+ * @author Eric Lafortune
+ */
+public class TracedVariables extends Variables
+{
+    public static final int NONE = -1;
+
+
+    private Value     producerValue;
+    private Variables producerVariables;
+    private int       initializationIndex;
+
+
+    /**
+     * Creates a new TracedVariables with a given size.
+     */
+    public TracedVariables(int size)
+    {
+        super(size);
+
+        producerVariables = new Variables(size);
+    }
+
+
+    /**
+     * Creates a new TracedVariables that is a copy of the given TracedVariables.
+     */
+    public TracedVariables(TracedVariables tracedVariables)
+    {
+        super(tracedVariables);
+
+        producerVariables = new Variables(tracedVariables.producerVariables);
+    }
+
+
+    /**
+     * Sets the Value that will be stored along with all store instructions.
+     */
+    public void setProducerValue(Value producerValue)
+    {
+        this.producerValue = producerValue;
+    }
+
+
+    /**
+     * Resets the initialization index.
+     */
+    public void resetInitialization()
+    {
+        initializationIndex = NONE;
+    }
+
+
+    /**
+     * Returns the most recent initialization index since it has been reset.
+     */
+    public int getInitializationIndex()
+    {
+        return initializationIndex;
+    }
+
+
+    /**
+     * Gets the producer Value for the specified variable, without disturbing it.
+     * @param index the variable index.
+     * @return the producer value of the given variable.
+     */
+    public Value getProducerValue(int index)
+    {
+        return producerVariables.getValue(index);
+    }
+
+
+    /**
+     * Sets the given producer Value for the specified variable, without
+     * disturbing it.
+     * @param index the variable index.
+     * @param value the producer value to set.
+     */
+    public void setProducerValue(int index, Value value)
+    {
+        producerVariables.store(index, value);
+    }
+
+
+    // Implementations for Variables.
+
+    public void reset(int size)
+    {
+        super.reset(size);
+
+        producerVariables.reset(size);
+    }
+
+    public void initialize(TracedVariables other)
+    {
+        super.initialize(other);
+
+        producerVariables.initialize(other.producerVariables);
+    }
+
+    public boolean generalize(TracedVariables other,
+                              boolean         clearConflictingOtherVariables)
+    {
+        boolean variablesChanged = super.generalize(other, clearConflictingOtherVariables);
+        boolean producersChanged = producerVariables.generalize(other.producerVariables, clearConflictingOtherVariables);
+        /* consumerVariables.generalize(other.consumerVariables)*/
+
+        // Clear any traces if a variable has become null.
+        if (variablesChanged)
+        {
+            for (int index = 0; index < size; index++)
+            {
+                if (values[index] == null)
+                {
+                    producerVariables.values[index] = null;
+
+                    if (clearConflictingOtherVariables)
+                    {
+                        other.producerVariables.values[index] = null;
+                    }
+                }
+            }
+        }
+
+        return variablesChanged || producersChanged;
+    }
+
+
+    public void store(int index, Value value)
+    {
+        // Is this store operation an initialization of the variable?
+        Value previousValue = super.load(index);
+        if (previousValue == null ||
+            previousValue.computationalType() != value.computationalType())
+        {
+            initializationIndex = index;
+        }
+
+        // Store the value itself in the variable.
+        super.store(index, value);
+
+        // Store the producer value in its producer variable.
+        producerVariables.store(index, producerValue);
+
+        // Account for the extra space required by Category 2 values.
+        if (value.isCategory2())
+        {
+            producerVariables.store(index+1, producerValue);
+        }
+    }
+
+
+    // Implementations for Object.
+
+    public boolean equals(Object object)
+    {
+        if (object == null ||
+            this.getClass() != object.getClass())
+        {
+            return false;
+        }
+
+        TracedVariables other = (TracedVariables)object;
+
+        return super.equals(object) &&
+               this.producerVariables.equals(other.producerVariables);
+    }
+
+
+    public int hashCode()
+    {
+        return super.hashCode() ^
+               producerVariables.hashCode();
+    }
+
+
+    public String toString()
+    {
+        StringBuffer buffer = new StringBuffer();
+
+        for (int index = 0; index < this.size(); index++)
+        {
+            Value value         = this.values[index];
+            Value producerValue = producerVariables.getValue(index);
+            buffer = buffer.append('[')
+                           .append(producerValue == null ? "empty:" : producerValue.toString())
+                           .append(value         == null ? "empty"  : value.toString())
+                           .append(']');
+        }
+
+        return buffer.toString();
+    }
+}