soot.jimple.spark.solver.SCCCollapser Maven / Gradle / Ivy
package soot.jimple.spark.solver;
/*-
* #%L
* Soot - a J*va Optimization Framework
* %%
* Copyright (C) 2002 Ondrej Lhotak
* %%
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 2.1 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 Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
import java.util.HashSet;
import java.util.TreeSet;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import soot.jimple.spark.internal.TypeManager;
import soot.jimple.spark.pag.Node;
import soot.jimple.spark.pag.PAG;
import soot.jimple.spark.pag.VarNode;
import soot.jimple.spark.sets.PointsToSetInternal;
/**
* Collapses VarNodes (green) forming strongly-connected components in the pointer assignment graph.
*
* @author Ondrej Lhotak
*/
public class SCCCollapser {
private static final Logger logger = LoggerFactory.getLogger(SCCCollapser.class);
/** Actually collapse the SCCs in the PAG. */
public void collapse() {
boolean verbose = pag.getOpts().verbose();
if (verbose) {
logger.debug("" + "Total VarNodes: " + pag.getVarNodeNumberer().size() + ". Collapsing SCCs...");
}
new TopoSorter(pag, ignoreTypes).sort();
TreeSet s = new TreeSet();
for (final VarNode v : pag.getVarNodeNumberer()) {
s.add(v);
}
for (VarNode v : s) {
dfsVisit(v, v);
}
if (verbose) {
logger.debug("" + "" + numCollapsed + " nodes were collapsed.");
}
visited = null;
}
public SCCCollapser(PAG pag, boolean ignoreTypes) {
this.pag = pag;
this.ignoreTypes = ignoreTypes;
this.typeManager = pag.getTypeManager();
}
/* End of public methods. */
/* End of package methods. */
protected int numCollapsed = 0;
protected PAG pag;
protected HashSet visited = new HashSet();
protected boolean ignoreTypes;
protected TypeManager typeManager;
final protected void dfsVisit(VarNode v, VarNode rootOfSCC) {
if (visited.contains(v)) {
return;
}
visited.add(v);
Node[] succs = pag.simpleInvLookup(v);
for (Node element : succs) {
if (ignoreTypes || typeManager.castNeverFails(element.getType(), v.getType())) {
dfsVisit((VarNode) element, rootOfSCC);
}
}
if (v != rootOfSCC) {
if (!ignoreTypes) {
if (typeManager.castNeverFails(v.getType(), rootOfSCC.getType())
&& typeManager.castNeverFails(rootOfSCC.getType(), v.getType())) {
rootOfSCC.mergeWith(v);
numCollapsed++;
}
} else /* ignoreTypes */ {
if (typeManager.castNeverFails(v.getType(), rootOfSCC.getType())) {
rootOfSCC.mergeWith(v);
} else if (typeManager.castNeverFails(rootOfSCC.getType(), v.getType())) {
v.mergeWith(rootOfSCC);
} else {
rootOfSCC.getReplacement().setType(null);
PointsToSetInternal set = rootOfSCC.getP2Set();
if (set != null) {
set.setType(null);
}
rootOfSCC.mergeWith(v);
}
numCollapsed++;
}
}
}
}