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/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification
 *             of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * 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 Stack saves additional information with stack elements, to keep track
 * of their origins.
 * 

* The stack 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, either taking * into account dup/swap instructions as proper instructions or ignoring them. * * @author Eric Lafortune */ public class TracedStack extends Stack { private Value producerValue; private Stack producerStack; private Stack actualProducerStack; /** * Creates a new TracedStack with a given maximum size. */ public TracedStack(int maxSize) { super(maxSize); producerStack = new Stack(maxSize); actualProducerStack = new Stack(maxSize); } /** * Creates a new TracedStack that is a copy of the given TracedStack. */ public TracedStack(TracedStack tracedStack) { super(tracedStack); producerStack = new Stack(tracedStack.producerStack); actualProducerStack = new Stack(tracedStack.actualProducerStack); } /** * Sets the Value that will be stored along with all push and pop * instructions. */ public void setProducerValue(Value producerValue) { this.producerValue = producerValue; } /** * Gets the specified producer Value from the stack, without disturbing it. * @param index the index of the stack element, counting from the bottom * of the stack. * @return the producer value at the specified position. */ public Value getBottomProducerValue(int index) { return producerStack.getBottom(index); } /** * Gets the specified actual producer Value from the stack, ignoring * dup/swap instructions, without disturbing it. * @param index the index of the stack element, counting from the bottom * of the stack. * @return the producer value at the specified position. */ public Value getBottomActualProducerValue(int index) { return actualProducerStack.getBottom(index); } /** * Gets the specified producer Value from the stack, without disturbing it. * @param index the index of the stack element, counting from the top * of the stack. * @return the producer value at the specified position. */ public Value getTopProducerValue(int index) { return producerStack.getTop(index); } /** * Gets the specified actual producer Value from the stack, ignoring * dup/swap instructions, without disturbing it. * @param index the index of the stack element, counting from the top * of the stack. * @return the producer value at the specified position. */ public Value getTopActualProducerValue(int index) { return actualProducerStack.getTop(index); } // Implementations for Stack. public void reset(int size) { super.reset(size); producerStack.reset(size); actualProducerStack.reset(size); } public void copy(TracedStack other) { super.copy(other); producerStack.copy(other.producerStack); actualProducerStack.copy(other.actualProducerStack); } public boolean generalize(TracedStack other) { return super.generalize(other) | producerStack.generalize(other.producerStack) | actualProducerStack.generalize(other.actualProducerStack); } public void clear() { super.clear(); producerStack.clear(); actualProducerStack.clear(); } public void removeTop(int index) { super.removeTop(index); producerStack.removeTop(index); actualProducerStack.removeTop(index); } public void push(Value value) { super.push(value); producerPush(); // Account for the extra space required by Category 2 values. if (value.isCategory2()) { producerPush(); } } public Value pop() { Value value = super.pop(); producerPop(); // Account for the extra space required by Category 2 values. if (value.isCategory2()) { producerPop(); } return value; } public void pop1() { super.pop1(); producerPop(); } public void pop2() { super.pop2(); producerPop(); producerPop(); } public void dup() { super.dup(); producerStack.pop(); producerStack.push(producerValue); producerStack.push(producerValue); actualProducerStack.dup(); } public void dup_x1() { super.dup_x1(); producerStack.pop(); producerStack.pop(); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); actualProducerStack.dup_x1(); } public void dup_x2() { super.dup_x2(); producerStack.pop(); producerStack.pop(); producerStack.pop(); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); actualProducerStack.dup_x2(); } public void dup2() { super.dup2(); producerStack.pop(); producerStack.pop(); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); actualProducerStack.dup2(); } public void dup2_x1() { super.dup2_x1(); producerStack.pop(); producerStack.pop(); producerStack.pop(); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); actualProducerStack.dup2_x1(); } public void dup2_x2() { super.dup2_x2(); producerStack.pop(); producerStack.pop(); producerStack.pop(); producerStack.pop(); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); producerStack.push(producerValue); actualProducerStack.dup2_x2(); } public void swap() { super.swap(); producerStack.pop(); producerStack.pop(); producerStack.push(producerValue); producerStack.push(producerValue); actualProducerStack.swap(); } // Implementations for Object. public boolean equals(Object object) { if (object == null || this.getClass() != object.getClass()) { return false; } TracedStack other = (TracedStack)object; return super.equals(object) && this.producerStack.equals(other.producerStack) && this.actualProducerStack.equals(other.actualProducerStack); } public int hashCode() { return super.hashCode() ^ producerStack.hashCode() ^ actualProducerStack.hashCode(); } public String toString() { StringBuffer buffer = new StringBuffer(); for (int index = 0; index < this.size(); index++) { Value value = this.values[index]; Value producerValue = producerStack.getBottom(index); Value actualProducerValue = actualProducerStack.getBottom(index); buffer = buffer.append('[') .append(producerValue == null ? "empty:" : producerValue.equals(actualProducerValue) ? producerValue.toString() : producerValue.toString() + actualProducerValue.toString()) .append(value == null ? "empty" : value.toString()) .append(']'); } return buffer.toString(); } // Small utility methods. private void producerPush() { producerStack.push(producerValue); actualProducerStack.push(producerValue); } private void producerPop() { producerStack.pop(); actualProducerStack.pop(); } }





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