soot.toolkits.scalar.ConstantInitializerToTagTransformer Maven / Gradle / Ivy
package soot.toolkits.scalar;
/*-
* #%L
* Soot - a J*va Optimization Framework
* %%
* Copyright (C) 1997 - 2018 Raja Vallée-Rai and others
* %%
* 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.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import soot.ConflictingFieldRefException;
import soot.Scene;
import soot.SceneTransformer;
import soot.SootClass;
import soot.SootField;
import soot.SootMethod;
import soot.Unit;
import soot.jimple.AssignStmt;
import soot.jimple.Constant;
import soot.jimple.DoubleConstant;
import soot.jimple.FieldRef;
import soot.jimple.FloatConstant;
import soot.jimple.IntConstant;
import soot.jimple.LongConstant;
import soot.jimple.StaticFieldRef;
import soot.jimple.StringConstant;
import soot.tagkit.ConstantValueTag;
import soot.tagkit.DoubleConstantValueTag;
import soot.tagkit.FloatConstantValueTag;
import soot.tagkit.IntegerConstantValueTag;
import soot.tagkit.LongConstantValueTag;
import soot.tagkit.StringConstantValueTag;
import soot.tagkit.Tag;
/**
* This is the reverse operation of the {@link ConstantValueToInitializerTransformer}. We scan for methods that
* initialize a final field with a constant value and create a {@link ConstantValueTag} from this value. Afterwards, the
* assignment in the method is removed. If runs empty, it is deleted as well.
*
* @author Steven Arzt
*/
public class ConstantInitializerToTagTransformer extends SceneTransformer {
private static final Logger logger = LoggerFactory.getLogger(ConstantInitializerToTagTransformer.class);
private static final ConstantInitializerToTagTransformer INSTANCE = new ConstantInitializerToTagTransformer();
public static ConstantInitializerToTagTransformer v() {
return INSTANCE;
}
@Override
protected void internalTransform(String phaseName, Map options) {
for (SootClass sc : Scene.v().getClasses()) {
transformClass(sc, false);
}
}
/**
* Transforms the given class, i.e. scans for a method and generates new constant value tags for all constant
* assignments to static final fields.
*
* @param sc
* The class to transform
* @param removeAssignments
* True if the assignments inside the method shall be removed, otherwise false
*/
public void transformClass(SootClass sc, boolean removeAssignments) {
// If this class has no method, we're done
SootMethod smInit = sc.getMethodByNameUnsafe("");
if (smInit == null || !smInit.isConcrete()) {
return;
}
Set nonConstantFields = new HashSet();
Map newTags = new HashMap();
Set removeTagList = new HashSet(); // in case of
// mismatch
// between
// code/constant
// table
// values,
// constant
// tags are
// removed
for (Iterator itU = smInit.getActiveBody().getUnits().snapshotIterator(); itU.hasNext();) {
Unit u = itU.next();
if (u instanceof AssignStmt) {
AssignStmt assign = (AssignStmt) u;
if (assign.getLeftOp() instanceof StaticFieldRef && assign.getRightOp() instanceof Constant) {
SootField field = null;
try {
field = ((StaticFieldRef) assign.getLeftOp()).getField();
if (field == null || nonConstantFields.contains(field)) {
continue;
}
} catch (ConflictingFieldRefException ex) {
// Ignore this statement
continue;
}
if (field.getDeclaringClass().equals(sc) && field.isStatic() && field.isFinal()) {
// Do we already have a constant value for this field?
boolean found = false;
for (Tag t : field.getTags()) {
if (t instanceof ConstantValueTag) {
if (checkConstantValue((ConstantValueTag) t, (Constant) assign.getRightOp())) {
// If we assign the same value we also have
// in the constant table, we can get rid of
// the assignment.
if (removeAssignments) {
itU.remove();
}
} else {
logger.debug("" + "WARNING: Constant value for field '" + field + "' mismatch between code ("
+ assign.getRightOp() + ") and constant table (" + t + ")");
removeTagList.add(field);
}
found = true;
break;
}
}
if (!found) {
// If we already have a different tag for this
// field,
// the value is not constant and we do not associate
// the
// tags.
if (!checkConstantValue(newTags.get(field), (Constant) assign.getRightOp())) {
nonConstantFields.add(field);
newTags.remove(field);
removeTagList.add(field);
continue;
}
ConstantValueTag newTag = createConstantTagFromValue((Constant) assign.getRightOp());
if (newTag != null) {
newTags.put(field, newTag);
}
}
}
} else if (assign.getLeftOp() instanceof StaticFieldRef) {
// a non-constant is assigned to the field
try {
SootField sf = ((StaticFieldRef) assign.getLeftOp()).getField();
if (sf != null) {
removeTagList.add(sf);
}
} catch (ConflictingFieldRefException ex) {
// let's assume that a broken field doesn't cause any
// harm
}
}
}
}
// Do the actual assignment
for (Entry entry : newTags.entrySet()) {
SootField field = entry.getKey();
if (removeTagList.contains(field)) {
continue;
}
field.addTag(entry.getValue());
}
if (removeAssignments && !newTags.isEmpty()) {
for (Iterator itU = smInit.getActiveBody().getUnits().snapshotIterator(); itU.hasNext();) {
Unit u = itU.next();
if (u instanceof AssignStmt) {
AssignStmt assign = (AssignStmt) u;
if (assign.getLeftOp() instanceof FieldRef) {
try {
SootField fld = ((FieldRef) assign.getLeftOp()).getField();
if (fld != null && newTags.containsKey(fld)) {
itU.remove();
}
} catch (ConflictingFieldRefException ex) {
// Ignore broken code
}
}
}
}
}
// remove constant tags
for (SootField sf : removeTagList) {
if (removeTagList.contains(sf)) {
List toRemoveTagList = new ArrayList();
for (Tag t : sf.getTags()) {
if (t instanceof ConstantValueTag) {
toRemoveTagList.add(t);
}
}
for (Tag t : toRemoveTagList) {
sf.getTags().remove(t);
}
}
}
}
private ConstantValueTag createConstantTagFromValue(Constant rightOp) {
if (rightOp instanceof DoubleConstant) {
return new DoubleConstantValueTag(((DoubleConstant) rightOp).value);
} else if (rightOp instanceof FloatConstant) {
return new FloatConstantValueTag(((FloatConstant) rightOp).value);
} else if (rightOp instanceof IntConstant) {
return new IntegerConstantValueTag(((IntConstant) rightOp).value);
} else if (rightOp instanceof LongConstant) {
return new LongConstantValueTag(((LongConstant) rightOp).value);
} else if (rightOp instanceof StringConstant) {
return new StringConstantValueTag(((StringConstant) rightOp).value);
} else {
return null;
}
}
private boolean checkConstantValue(ConstantValueTag t, Constant rightOp) {
if (t == null || rightOp == null) {
return true;
}
if (t instanceof DoubleConstantValueTag) {
if (!(rightOp instanceof DoubleConstant)) {
return false;
}
return ((DoubleConstantValueTag) t).getDoubleValue() == ((DoubleConstant) rightOp).value;
} else if (t instanceof FloatConstantValueTag) {
if (!(rightOp instanceof FloatConstant)) {
return false;
}
return ((FloatConstantValueTag) t).getFloatValue() == ((FloatConstant) rightOp).value;
} else if (t instanceof IntegerConstantValueTag) {
if (!(rightOp instanceof IntConstant)) {
return false;
}
return ((IntegerConstantValueTag) t).getIntValue() == ((IntConstant) rightOp).value;
} else if (t instanceof LongConstantValueTag) {
if (!(rightOp instanceof LongConstant)) {
return false;
}
return ((LongConstantValueTag) t).getLongValue() == ((LongConstant) rightOp).value;
} else if (t instanceof StringConstantValueTag) {
if (!(rightOp instanceof StringConstant)) {
return false;
}
return ((StringConstantValueTag) t).getStringValue().equals(((StringConstant) rightOp).value);
} else {
// We don't know the type, so we assume it's alright
return true;
}
}
}