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152 lines
3.7 KiB
152 lines
3.7 KiB
/*
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* Copyright 2000-2015 JetBrains s.r.o.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.jetbrains.java.decompiler.modules.decompiler.decompose;
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import org.jetbrains.java.decompiler.util.VBStyleCollection;
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import java.util.List;
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import java.util.Set;
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public class GenericDominatorEngine {
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private final IGraph graph;
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private final VBStyleCollection<IGraphNode, IGraphNode> colOrderedIDoms = new VBStyleCollection<>();
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private Set<? extends IGraphNode> setRoots;
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public GenericDominatorEngine(IGraph graph) {
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this.graph = graph;
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}
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public void initialize() {
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calcIDoms();
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}
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private void orderNodes() {
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setRoots = graph.getRoots();
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for (IGraphNode node : graph.getReversePostOrderList()) {
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colOrderedIDoms.addWithKey(null, node);
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}
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}
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private static IGraphNode getCommonIDom(IGraphNode node1, IGraphNode node2, VBStyleCollection<IGraphNode, IGraphNode> orderedIDoms) {
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IGraphNode nodeOld;
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if (node1 == null) {
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return node2;
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}
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else if (node2 == null) {
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return node1;
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}
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int index1 = orderedIDoms.getIndexByKey(node1);
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int index2 = orderedIDoms.getIndexByKey(node2);
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while (index1 != index2) {
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if (index1 > index2) {
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nodeOld = node1;
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node1 = orderedIDoms.getWithKey(node1);
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if (nodeOld == node1) { // no idom - root or merging point
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return null;
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}
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index1 = orderedIDoms.getIndexByKey(node1);
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}
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else {
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nodeOld = node2;
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node2 = orderedIDoms.getWithKey(node2);
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if (nodeOld == node2) { // no idom - root or merging point
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return null;
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}
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index2 = orderedIDoms.getIndexByKey(node2);
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}
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}
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return node1;
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}
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private void calcIDoms() {
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orderNodes();
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List<IGraphNode> lstNodes = colOrderedIDoms.getLstKeys();
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while (true) {
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boolean changed = false;
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for (IGraphNode node : lstNodes) {
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IGraphNode idom = null;
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if (!setRoots.contains(node)) {
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for (IGraphNode pred : node.getPredecessors()) {
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if (colOrderedIDoms.getWithKey(pred) != null) {
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idom = getCommonIDom(idom, pred, colOrderedIDoms);
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if (idom == null) {
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break; // no idom found: merging point of two trees
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}
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}
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}
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}
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if (idom == null) {
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idom = node;
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}
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IGraphNode oldidom = colOrderedIDoms.putWithKey(idom, node);
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if (!idom.equals(oldidom)) { // oldidom is null iff the node is touched for the first time
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changed = true;
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}
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}
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if (!changed) {
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break;
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}
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}
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}
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public VBStyleCollection<IGraphNode, IGraphNode> getOrderedIDoms() {
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return colOrderedIDoms;
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}
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public boolean isDominator(IGraphNode node, IGraphNode dom) {
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while (!node.equals(dom)) {
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IGraphNode idom = colOrderedIDoms.getWithKey(node);
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if (idom == node) {
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return false; // root node or merging point
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}
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else if (idom == null) {
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throw new RuntimeException("Inconsistent idom sequence discovered!");
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}
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else {
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node = idom;
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}
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}
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return true;
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}
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}
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