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A Java Optimization Framework
package soot.jimple.toolkits.annotation.arraycheck;
/*-
* #%L
* Soot - a J*va Optimization Framework
* %%
* Copyright (C) 2000 Feng Qian
* %%
* 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.Collection;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import soot.ArrayType;
import soot.Body;
import soot.G;
import soot.Local;
import soot.Modifier;
import soot.Singletons;
import soot.SootClass;
import soot.SootField;
import soot.SootMethod;
import soot.Type;
import soot.Unit;
import soot.Value;
import soot.jimple.AssignStmt;
import soot.jimple.DefinitionStmt;
import soot.jimple.FieldRef;
import soot.jimple.IntConstant;
import soot.jimple.NewArrayExpr;
import soot.jimple.NewMultiArrayExpr;
import soot.jimple.Stmt;
import soot.options.Options;
import soot.toolkits.scalar.LocalDefs;
public class ClassFieldAnalysis {
private static final Logger logger = LoggerFactory.getLogger(ClassFieldAnalysis.class);
public ClassFieldAnalysis(Singletons.Global g) {
}
public static ClassFieldAnalysis v() {
return G.v().soot_jimple_toolkits_annotation_arraycheck_ClassFieldAnalysis();
}
private final boolean final_in = true;
private final boolean private_in = true;
/*
* A map hold class object to other information
*
* SootClass --> FieldInfoTable
*/
private final Map> classToFieldInfoMap
= new HashMap>();
protected void internalTransform(SootClass c) {
if (classToFieldInfoMap.containsKey(c)) {
return;
}
/* Summerize class information here. */
Date start = new Date();
if (Options.v().verbose()) {
logger.debug("[] ClassFieldAnalysis started on : " + start + " for " + c.getPackageName() + c.getName());
}
Hashtable fieldInfoTable = new Hashtable();
classToFieldInfoMap.put(c, fieldInfoTable);
/*
* Who is the candidate for analysis? Int, Array, field. Also it should be PRIVATE now.
*/
HashSet candidSet = new HashSet();
int arrayTypeFieldNum = 0;
Iterator fieldIt = c.getFields().iterator();
while (fieldIt.hasNext()) {
SootField field = fieldIt.next();
int modifiers = field.getModifiers();
Type type = field.getType();
if (type instanceof ArrayType) {
if ((final_in && ((modifiers & Modifier.FINAL) != 0)) || (private_in && ((modifiers & Modifier.PRIVATE) != 0))) {
candidSet.add(field);
arrayTypeFieldNum++;
}
}
}
if (arrayTypeFieldNum == 0) {
if (Options.v().verbose()) {
logger.debug("[] ClassFieldAnalysis finished with nothing");
}
return;
}
/* For FINAL field, it only needs to scan the and methods. */
/*
* For PRIVATE field, is scanned to make sure that it is always assigned a value before other uses. And no other
* assignment in other methods.
*/
/*
* The fastest way to determine the value of one field may get. Scan all method to get all definitions, and summerize the
* final value. For PRIVATE STATIC field, if it is not always assigned value, it may count null pointer exception before
* array exception
*/
Iterator methodIt = c.methodIterator();
while (methodIt.hasNext()) {
ScanMethod(methodIt.next(), candidSet, fieldInfoTable);
}
Date finish = new Date();
if (Options.v().verbose()) {
long runtime = finish.getTime() - start.getTime();
long mins = runtime / 60000;
long secs = (runtime % 60000) / 1000;
logger.debug("[] ClassFieldAnalysis finished normally. " + "It took " + mins + " mins and " + secs + " secs.");
}
}
public Object getFieldInfo(SootField field) {
SootClass c = field.getDeclaringClass();
Map fieldInfoTable = classToFieldInfoMap.get(c);
if (fieldInfoTable == null) {
internalTransform(c);
fieldInfoTable = classToFieldInfoMap.get(c);
}
return fieldInfoTable.get(field);
}
/*
* method, to be scanned candidates, the candidate set of fields, fields with value TOP are moved out of the set.
* fieldinfo, keep the field -> value.
*/
public void ScanMethod(SootMethod method, Set candidates, Hashtable fieldinfo) {
if (!method.isConcrete()) {
return;
}
Body body = method.retrieveActiveBody();
if (body == null) {
return;
}
/* no array locals, then definitely it has no array type field references. */
{
boolean hasArrayLocal = false;
Collection locals = body.getLocals();
Iterator localIt = locals.iterator();
while (localIt.hasNext()) {
Local local = localIt.next();
Type type = local.getType();
if (type instanceof ArrayType) {
hasArrayLocal = true;
break;
}
}
if (!hasArrayLocal) {
return;
}
}
/* only take care of the first dimension of array size */
/* check the assignment of fields. */
/* Linearly scan the method body, if it has field references in candidate set. */
/*
* Only a.f = ... needs consideration. this.f, or other.f are treated as same because we summerize the field as a class's
* field.
*/
HashMap stmtfield = new HashMap();
{
Iterator unitIt = body.getUnits().iterator();
while (unitIt.hasNext()) {
Stmt stmt = (Stmt) unitIt.next();
if (stmt.containsFieldRef()) {
Value leftOp = ((AssignStmt) stmt).getLeftOp();
if (leftOp instanceof FieldRef) {
FieldRef fref = (FieldRef) leftOp;
SootField field = fref.getField();
if (candidates.contains(field)) {
stmtfield.put(stmt, field);
}
}
}
}
if (stmtfield.size() == 0) {
return;
}
}
if (Options.v().verbose()) {
logger.debug("[] ScanMethod for field started.");
}
/* build D/U web, find the value of each candidate */
{
LocalDefs localDefs = LocalDefs.Factory.newLocalDefs(body);
Set> entries = stmtfield.entrySet();
Iterator> entryIt = entries.iterator();
while (entryIt.hasNext()) {
Map.Entry entry = entryIt.next();
Stmt where = entry.getKey();
SootField which = entry.getValue();
IntValueContainer length = new IntValueContainer();
// take out the right side of assign stmt
Value rightOp = ((AssignStmt) where).getRightOp();
if (rightOp instanceof Local) {
// tracing down the defs of right side local.
Local local = (Local) rightOp;
DefinitionStmt usestmt = (DefinitionStmt) where;
while (length.isBottom()) {
List defs = localDefs.getDefsOfAt(local, usestmt);
if (defs.size() == 1) {
usestmt = (DefinitionStmt) defs.get(0);
if (Options.v().debug()) {
logger.debug(" " + usestmt);
}
Value tmp_rhs = usestmt.getRightOp();
if ((tmp_rhs instanceof NewArrayExpr) || (tmp_rhs instanceof NewMultiArrayExpr)) {
Value size;
if (tmp_rhs instanceof NewArrayExpr) {
size = ((NewArrayExpr) tmp_rhs).getSize();
} else {
size = ((NewMultiArrayExpr) tmp_rhs).getSize(0);
}
if (size instanceof IntConstant) {
length.setValue(((IntConstant) size).value);
} else if (size instanceof Local) {
local = (Local) size;
// defs = localDefs.getDefsOfAt((Local)size, (Unit)usestmt);
continue;
} else {
length.setTop();
}
} else if (tmp_rhs instanceof IntConstant) {
length.setValue(((IntConstant) tmp_rhs).value);
} else if (tmp_rhs instanceof Local) {
// defs = localDefs.getDefsOfAt((Local)tmp_rhs, usestmt);
local = (Local) tmp_rhs;
continue;
} else {
length.setTop();
}
} else {
length.setTop();
}
}
} else {
/* it could be null */
continue;
}
IntValueContainer oldv = fieldinfo.get(which);
/* the length is top, set the field to top */
if (length.isTop()) {
if (oldv == null) {
fieldinfo.put(which, length.dup());
} else {
oldv.setTop();
}
/* remove from the candidate set. */
candidates.remove(which);
} else if (length.isInteger()) {
if (oldv == null) {
fieldinfo.put(which, length.dup());
} else {
if (oldv.isInteger() && oldv.getValue() != length.getValue()) {
oldv.setTop();
candidates.remove(which);
}
}
}
}
}
if (Options.v().verbose()) {
logger.debug("[] ScanMethod finished.");
}
}
}
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