113 lines
3.0 KiB
Java
113 lines
3.0 KiB
Java
/*******************************************************************************
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* Copyright (c) 2002,2006 IBM Corporation.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* IBM Corporation - initial API and implementation
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*******************************************************************************/
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package com.ibm.wala.shrikeBT;
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/**
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* This class represents dup instructions. There are two kinds of dup instructions, dup and dup_x1:
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*
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* dup: a::rest => a::a::rest dup_x1: a::b::rest => a::b::a::rest
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*/
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public final class DupInstruction extends Instruction {
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final private int size;
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final private byte delta;
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protected DupInstruction(byte size, byte delta) {
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super((short) -1);
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this.size = size;
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this.delta = delta;
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}
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private final static DupInstruction[] preallocated = preallocate();
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private static DupInstruction[] preallocate() {
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DupInstruction[] r = new DupInstruction[9];
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for (int i = 0; i < r.length; i++) {
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r[i] = new DupInstruction((byte) (i / 3), (byte) (i % 3));
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}
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return r;
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}
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/**
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* DupInstructions with size or delta 2 might cause code generation failures when the working stack contains long or double
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* values, when these DupInstructions cannot be easily translated into Java bytecode instructions. For safety, avoid using
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* DupInstructions with size or delta 2.
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*
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* Don't create these outside the shrikeBT decoder.
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*/
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static DupInstruction make(int size, int delta) {
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if (size < 0 || size > 2) {
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throw new IllegalArgumentException("Invalid dup size: " + size);
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}
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if (delta < 0 || delta > 2) {
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throw new IllegalArgumentException("Invalid dup delta: " + delta);
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}
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return preallocated[size * 3 + delta];
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}
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/**
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* @param delta 0 for dup, 1 for dup_x1
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*/
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public static DupInstruction make(int delta) {
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if (delta < 0 || delta > 1) {
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throw new IllegalArgumentException("Invalid dup delta: " + delta);
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}
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return make(1, delta);
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}
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@Override
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public boolean equals(Object o) {
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if (o instanceof DupInstruction) {
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DupInstruction i = (DupInstruction) o;
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return i.size == size && i.delta == delta;
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} else {
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return false;
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}
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}
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public int getSize() {
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return size;
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}
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public int getDelta() {
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return delta;
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}
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@Override
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public int hashCode() {
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return size + 8431890 + 10 * delta;
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}
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@Override
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public int getPoppedCount() {
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return size + delta;
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}
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@Override
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public String toString() {
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return "Dup(" + size + "," + delta + ")";
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}
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@Override
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public void visit(IInstruction.Visitor v) {
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if (v == null) {
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throw new IllegalArgumentException("illegal null visitor");
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}
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v.visitDup(this);
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}
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@Override
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public boolean isPEI() {
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return false;
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}
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}
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