/*
* ReverseCFATransformerFactory.java - This file is part of the Jakstab project.
* Copyright 2007-2012 Johannes Kinder <jk@jakstab.org>
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, see <http://www.gnu.org/licenses/>.
*/
package org.jakstab.cfa;
import java.util.HashSet;
import java.util.Set;
import org.jakstab.analysis.AbstractState;
import org.jakstab.asm.AbsoluteAddress;
import org.jakstab.cfa.Location;
import org.jakstab.rtl.statements.RTLSkip;
import org.jakstab.util.FastSet;
import org.jakstab.util.Logger;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.SetMultimap;
public class ReverseCFATransformerFactory implements StateTransformerFactory {
@SuppressWarnings("unused")
private static final Logger logger = Logger.getLogger(ReverseCFATransformerFactory.class);
private SetMultimap<Location,CFAEdge> reverseCFA;
private Location sink;
public ReverseCFATransformerFactory(Set<CFAEdge> cfa) {
reverseCFA = HashMultimap.create();
Set<Location> nonSinks = new HashSet<Location>();
for (CFAEdge e : cfa) {
reverseCFA.put(e.getTarget(), e);
nonSinks.add(e.getSource());
}
FastSet<Location> sinks = new FastSet<Location>();
for (Location l : reverseCFA.keySet()) {
if (!nonSinks.contains(l)) {
sinks.add(l);
}
}
if (sinks.size() == 1) {
sink = sinks.pick();
} else if (sinks.size() == 0) {
throw new RuntimeException("CFA has no sink!");
} else {
// Generate artificial exit node
sink = new Location(new AbsoluteAddress(0xFFFFFF01L));
for (Location l : sinks) {
reverseCFA.put(sink, new CFAEdge(l, sink, new RTLSkip()));
}
}
}
@Override
public Set<CFAEdge> getTransformers(AbstractState a) {
return reverseCFA.get(a.getLocation());
}
@Override
public Location getInitialLocation() {
return sink;
}
}