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399 lines
13 KiB
399 lines
13 KiB
// Copyright 2000-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
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package org.jetbrains.java.decompiler.modules.decompiler;
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import org.jetbrains.java.decompiler.code.cfg.BasicBlock;
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import org.jetbrains.java.decompiler.main.DecompilerContext;
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import org.jetbrains.java.decompiler.main.collectors.CounterContainer;
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import org.jetbrains.java.decompiler.modules.decompiler.exps.AssignmentExprent;
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import org.jetbrains.java.decompiler.modules.decompiler.exps.Exprent;
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import org.jetbrains.java.decompiler.modules.decompiler.exps.IfExprent;
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import org.jetbrains.java.decompiler.modules.decompiler.stats.*;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Set;
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public final class MergeHelper {
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public static void enhanceLoops(Statement root) {
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while (enhanceLoopsRec(root)) /**/;
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SequenceHelper.condenseSequences(root);
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}
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private static boolean enhanceLoopsRec(Statement stat) {
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boolean res = false;
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for (Statement st : stat.getStats()) {
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if (st.getExprents() == null) {
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res |= enhanceLoopsRec(st);
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}
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}
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if (stat.type == Statement.TYPE_DO) {
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res |= enhanceLoop((DoStatement)stat);
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}
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return res;
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}
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private static boolean enhanceLoop(DoStatement stat) {
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int oldloop = stat.getLooptype();
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switch (oldloop) {
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case DoStatement.LOOP_DO:
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// identify a while loop
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if (matchWhile(stat)) {
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// identify a for loop - subtype of while
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matchFor(stat);
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}
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else {
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// identify a do{}while loop
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matchDoWhile(stat);
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}
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break;
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case DoStatement.LOOP_WHILE:
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matchFor(stat);
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}
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return (stat.getLooptype() != oldloop);
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}
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private static void matchDoWhile(DoStatement stat) {
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// search for an if condition at the end of the loop
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Statement last = stat.getFirst();
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while (last.type == Statement.TYPE_SEQUENCE) {
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last = last.getStats().getLast();
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}
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if (last.type == Statement.TYPE_IF) {
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IfStatement lastif = (IfStatement)last;
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if (lastif.iftype == IfStatement.IFTYPE_IF && lastif.getIfstat() == null) {
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StatEdge ifedge = lastif.getIfEdge();
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StatEdge elseedge = lastif.getAllSuccessorEdges().get(0);
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if ((ifedge.getType() == StatEdge.TYPE_BREAK && elseedge.getType() == StatEdge.TYPE_CONTINUE && elseedge.closure == stat
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&& isDirectPath(stat, ifedge.getDestination())) ||
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(ifedge.getType() == StatEdge.TYPE_CONTINUE && elseedge.getType() == StatEdge.TYPE_BREAK && ifedge.closure == stat
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&& isDirectPath(stat, elseedge.getDestination()))) {
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Set<Statement> set = stat.getNeighboursSet(StatEdge.TYPE_CONTINUE, Statement.DIRECTION_BACKWARD);
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set.remove(last);
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if (!set.isEmpty()) {
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return;
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}
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stat.setLooptype(DoStatement.LOOP_DOWHILE);
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IfExprent ifexpr = (IfExprent)lastif.getHeadexprent().copy();
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if (ifedge.getType() == StatEdge.TYPE_BREAK) {
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ifexpr.negateIf();
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}
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stat.setConditionExprent(ifexpr.getCondition());
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lastif.getFirst().removeSuccessor(ifedge);
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lastif.removeSuccessor(elseedge);
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// remove empty if
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if (lastif.getFirst().getExprents().isEmpty()) {
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removeLastEmptyStatement(stat, lastif);
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}
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else {
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lastif.setExprents(lastif.getFirst().getExprents());
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StatEdge newedge = new StatEdge(StatEdge.TYPE_CONTINUE, lastif, stat);
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lastif.addSuccessor(newedge);
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stat.addLabeledEdge(newedge);
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}
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if (stat.getAllSuccessorEdges().isEmpty()) {
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StatEdge edge = elseedge.getType() == StatEdge.TYPE_CONTINUE ? ifedge : elseedge;
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edge.setSource(stat);
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if (edge.closure == stat) {
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edge.closure = stat.getParent();
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}
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stat.addSuccessor(edge);
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}
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}
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}
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}
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}
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private static boolean matchWhile(DoStatement stat) {
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// search for an if condition at the entrance of the loop
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Statement first = stat.getFirst();
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while (first.type == Statement.TYPE_SEQUENCE) {
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first = first.getFirst();
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}
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// found an if statement
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if (first.type == Statement.TYPE_IF) {
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IfStatement firstif = (IfStatement)first;
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if (firstif.getFirst().getExprents().isEmpty()) {
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if (firstif.iftype == IfStatement.IFTYPE_IF) {
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if (firstif.getIfstat() == null) {
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StatEdge ifedge = firstif.getIfEdge();
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if (isDirectPath(stat, ifedge.getDestination())) {
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// exit condition identified
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stat.setLooptype(DoStatement.LOOP_WHILE);
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// negate condition (while header)
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IfExprent ifexpr = (IfExprent)firstif.getHeadexprent().copy();
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ifexpr.negateIf();
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stat.setConditionExprent(ifexpr.getCondition());
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// remove edges
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firstif.getFirst().removeSuccessor(ifedge);
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firstif.removeSuccessor(firstif.getAllSuccessorEdges().get(0));
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if (stat.getAllSuccessorEdges().isEmpty()) {
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ifedge.setSource(stat);
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if (ifedge.closure == stat) {
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ifedge.closure = stat.getParent();
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}
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stat.addSuccessor(ifedge);
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}
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// remove empty if statement as it is now part of the loop
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if (firstif == stat.getFirst()) {
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BasicBlockStatement bstat = new BasicBlockStatement(new BasicBlock(
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DecompilerContext.getCounterContainer().getCounterAndIncrement(CounterContainer.STATEMENT_COUNTER)));
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bstat.setExprents(new ArrayList<>());
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stat.replaceStatement(firstif, bstat);
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}
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else {
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// precondition: sequence must contain more than one statement!
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Statement sequence = firstif.getParent();
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sequence.getStats().removeWithKey(firstif.id);
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sequence.setFirst(sequence.getStats().get(0));
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}
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return true;
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}
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}
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else {
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StatEdge elseedge = firstif.getAllSuccessorEdges().get(0);
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if (isDirectPath(stat, elseedge.getDestination())) {
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// exit condition identified
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stat.setLooptype(DoStatement.LOOP_WHILE);
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// no need to negate the while condition
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stat.setConditionExprent(((IfExprent)firstif.getHeadexprent().copy()).getCondition());
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// remove edges
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StatEdge ifedge = firstif.getIfEdge();
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firstif.getFirst().removeSuccessor(ifedge);
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firstif.removeSuccessor(elseedge);
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if (stat.getAllSuccessorEdges().isEmpty()) {
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elseedge.setSource(stat);
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if (elseedge.closure == stat) {
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elseedge.closure = stat.getParent();
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}
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stat.addSuccessor(elseedge);
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}
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if (firstif.getIfstat() == null) {
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BasicBlockStatement bstat = new BasicBlockStatement(new BasicBlock(
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DecompilerContext.getCounterContainer().getCounterAndIncrement(CounterContainer.STATEMENT_COUNTER)));
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bstat.setExprents(new ArrayList<>());
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ifedge.setSource(bstat);
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bstat.addSuccessor(ifedge);
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stat.replaceStatement(firstif, bstat);
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}
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else {
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// replace the if statement with its content
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first.getParent().replaceStatement(first, firstif.getIfstat());
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// lift closures
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for (StatEdge prededge : elseedge.getDestination().getPredecessorEdges(StatEdge.TYPE_BREAK)) {
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if (stat.containsStatementStrict(prededge.closure)) {
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stat.addLabeledEdge(prededge);
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}
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}
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LabelHelper.lowClosures(stat);
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}
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return true;
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}
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}
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}
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}
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}
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return false;
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}
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public static boolean isDirectPath(Statement stat, Statement endstat) {
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Set<Statement> setStat = stat.getNeighboursSet(Statement.STATEDGE_DIRECT_ALL, Statement.DIRECTION_FORWARD);
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if (setStat.isEmpty()) {
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Statement parent = stat.getParent();
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if (parent == null) {
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return false;
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}
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else {
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switch (parent.type) {
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case Statement.TYPE_ROOT:
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return endstat.type == Statement.TYPE_DUMMYEXIT;
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case Statement.TYPE_DO:
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return (endstat == parent);
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case Statement.TYPE_SWITCH:
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SwitchStatement swst = (SwitchStatement)parent;
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for (int i = 0; i < swst.getCaseStatements().size() - 1; i++) {
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Statement stt = swst.getCaseStatements().get(i);
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if (stt == stat) {
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Statement stnext = swst.getCaseStatements().get(i + 1);
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if (stnext.getExprents() != null && stnext.getExprents().isEmpty()) {
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stnext = stnext.getAllSuccessorEdges().get(0).getDestination();
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}
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return (endstat == stnext);
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}
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}
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default:
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return isDirectPath(parent, endstat);
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}
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}
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}
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else {
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return setStat.contains(endstat);
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}
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}
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private static void matchFor(DoStatement stat) {
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Exprent lastDoExprent, initDoExprent = null;
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Statement lastData, preData = null;
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// get last exprent
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lastData = getLastDirectData(stat.getFirst());
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if (lastData == null || lastData.getExprents().isEmpty()) {
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return;
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}
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List<Exprent> lstExpr = lastData.getExprents();
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lastDoExprent = lstExpr.get(lstExpr.size() - 1);
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boolean haslast = lastDoExprent.type == Exprent.EXPRENT_ASSIGNMENT || lastDoExprent.type == Exprent.EXPRENT_FUNCTION;
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if (!haslast) {
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return;
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}
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boolean hasinit = false;
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// search for an initializing exprent
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Statement current = stat;
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while (true) {
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Statement parent = current.getParent();
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if (parent == null) {
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break;
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}
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if (parent.type == Statement.TYPE_SEQUENCE) {
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if (current == parent.getFirst()) {
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current = parent;
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}
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else {
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preData = current.getNeighbours(StatEdge.TYPE_REGULAR, Statement.DIRECTION_BACKWARD).get(0);
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preData = getLastDirectData(preData);
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if (preData != null && !preData.getExprents().isEmpty()) {
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initDoExprent = preData.getExprents().get(preData.getExprents().size() - 1);
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if (initDoExprent.type == Exprent.EXPRENT_ASSIGNMENT) {
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hasinit = true;
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}
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}
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break;
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}
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}
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else {
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break;
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}
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}
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if (!hasinit) {
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return;
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}
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Exprent initVar = ((AssignmentExprent) initDoExprent).getLeft();
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Exprent incVar;
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if (lastDoExprent.type == Exprent.EXPRENT_ASSIGNMENT) {
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incVar = ((AssignmentExprent) lastDoExprent).getLeft();
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} else {
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incVar = lastDoExprent.getAllExprents().get(0);
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}
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if (!initVar.equals(incVar)) {
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return;
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}
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if (!stat.getConditionExprent().containsExprent(initVar)) {
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return;
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}
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Set<Statement> set = stat.getNeighboursSet(StatEdge.TYPE_CONTINUE, Statement.DIRECTION_BACKWARD);
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set.remove(lastData);
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if (!set.isEmpty()) {
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return;
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}
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stat.setLooptype(DoStatement.LOOP_FOR);
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stat.setInitExprent(preData.getExprents().remove(preData.getExprents().size() - 1));
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stat.setIncExprent(lastData.getExprents().remove(lastData.getExprents().size() - 1));
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if (lastData.getExprents().isEmpty()) {
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List<StatEdge> lst = lastData.getAllSuccessorEdges();
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if (!lst.isEmpty()) {
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lastData.removeSuccessor(lst.get(0));
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}
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removeLastEmptyStatement(stat, lastData);
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}
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}
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private static void removeLastEmptyStatement(DoStatement dostat, Statement stat) {
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if (stat == dostat.getFirst()) {
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BasicBlockStatement bstat = new BasicBlockStatement(new BasicBlock(
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DecompilerContext.getCounterContainer().getCounterAndIncrement(CounterContainer.STATEMENT_COUNTER)));
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bstat.setExprents(new ArrayList<>());
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dostat.replaceStatement(stat, bstat);
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}
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else {
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for (StatEdge edge : stat.getAllPredecessorEdges()) {
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edge.getSource().changeEdgeType(Statement.DIRECTION_FORWARD, edge, StatEdge.TYPE_CONTINUE);
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stat.removePredecessor(edge);
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edge.getSource().changeEdgeNode(Statement.DIRECTION_FORWARD, edge, dostat);
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dostat.addPredecessor(edge);
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dostat.addLabeledEdge(edge);
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}
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// parent is a sequence statement
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stat.getParent().getStats().removeWithKey(stat.id);
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}
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}
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private static Statement getLastDirectData(Statement stat) {
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if (stat.getExprents() != null) {
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return stat;
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}
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if (stat.type == Statement.TYPE_SEQUENCE) {
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for (int i = stat.getStats().size() - 1; i >= 0; i--) {
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Statement tmp = getLastDirectData(stat.getStats().get(i));
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if (tmp == null || !tmp.getExprents().isEmpty()) {
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return tmp;
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}
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}
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}
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return null;
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}
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} |