Examples with UnknownType soot.UnknownType used on opensource projects

Example 6 with UnknownType

use of soot.UnknownType in project soot by Sable.

the class LocalNameStandardizer method internalTransform.

@Override
protected void internalTransform(Body body, String phaseName, Map<String, String> options) {
    boolean onlyStackName = PhaseOptions.getBoolean(options, "only-stack-locals");
    boolean sortLocals = PhaseOptions.getBoolean(options, "sort-locals");
    final BooleanType booleanType = BooleanType.v();
    final ByteType byteType = ByteType.v();
    final ShortType shortType = ShortType.v();
    final CharType charType = CharType.v();
    final IntType intType = IntType.v();
    final LongType longType = LongType.v();
    final DoubleType doubleType = DoubleType.v();
    final FloatType floatType = FloatType.v();
    final ErroneousType erroneousType = ErroneousType.v();
    final UnknownType unknownType = UnknownType.v();
    final StmtAddressType stmtAddressType = StmtAddressType.v();
    final NullType nullType = NullType.v();
    // Change the names to the standard forms now.
    {
        int objectCount = 0;
        int intCount = 0;
        int longCount = 0;
        int floatCount = 0;
        int doubleCount = 0;
        int addressCount = 0;
        int errorCount = 0;
        int nullCount = 0;
        /* The goal of this option is to ensure that local ordering remains
             * consistent between different iterations of soot. This helps to ensure
             * things like stable string representations of instructions and stable
             * jimple representations of a methods body when soot is used to load
             * the same code in different iterations.
             * 
             * First sorts the locals alphabetically by the string representation of
             * their type. Then if there are two locals with the same type, it uses
             * the only other source of structurally stable information (i.e. the 
             * instructions themselves) to produce an ordering for the locals
             * that remains consistent between different soot instances. It achieves
             * this by determining the position of a local's first occurrence in the 
             * instruction's list of definition statements. This position is then used
             * to sort the locals with the same type in an ascending order. 
             * 
             * The only times that this may not produce a consistent ordering for the 
             * locals between different soot instances is if a local is never defined in
             * the instructions or if the instructions themselves are changed in some way
             * that effects the ordering of the locals. In the first case, if a local is 
             * never defined, the other jimple body phases will remove this local as it is 
             * unused. As such, all we have to do is rerun this LocalNameStandardizer after
             * all other jimple body phases to eliminate any ambiguity introduced by these
             * phases and by the removed unused locals. In the second case, if the instructions
             * themselves changed then the user would have had to intentionally told soot to
             * modify the instructions of the code. Otherwise, the instructions would not have
             * changed because we assume the instructions to always be structurally stable
             * between different instances of soot. As such, in this instance, the user should
             * not be expecting soot to produce the same output as the input and thus the
             * ordering of the locals does not matter.
             */
        if (sortLocals) {
            Chain<Local> locals = body.getLocals();
            final List<ValueBox> defs = body.getDefBoxes();
            ArrayList<Local> sortedLocals = new ArrayList<Local>(locals);
            Collections.sort(sortedLocals, new Comparator<Local>() {

                private Map<Local, Integer> firstOccuranceCache = new HashMap<Local, Integer>();

                @Override
                public int compare(Local arg0, Local arg1) {
                    int ret = arg0.getType().toString().compareTo(arg1.getType().toString());
                    if (ret == 0) {
                        ret = Integer.compare(getFirstOccurance(arg0), getFirstOccurance(arg1));
                    }
                    return ret;
                }

                private int getFirstOccurance(Local l) {
                    Integer cur = firstOccuranceCache.get(l);
                    if (cur != null) {
                        return cur;
                    } else {
                        int count = 0;
                        int first = -1;
                        for (ValueBox vb : defs) {
                            Value v = vb.getValue();
                            if (v instanceof Local && v.equals(l)) {
                                first = count;
                                break;
                            }
                            count++;
                        }
                        firstOccuranceCache.put(l, first);
                        return first;
                    }
                }
            });
            locals.clear();
            locals.addAll(sortedLocals);
        }
        for (Local l : body.getLocals()) {
            String prefix = "";
            if (l.getName().startsWith("$"))
                prefix = "$";
            else {
                if (onlyStackName)
                    continue;
            }
            final Type type = l.getType();
            if (type.equals(booleanType))
                l.setName(prefix + "z" + intCount++);
            else if (type.equals(byteType))
                l.setName(prefix + "b" + longCount++);
            else if (type.equals(shortType))
                l.setName(prefix + "s" + longCount++);
            else if (type.equals(charType))
                l.setName(prefix + "c" + longCount++);
            else if (type.equals(intType))
                l.setName(prefix + "i" + longCount++);
            else if (type.equals(longType))
                l.setName(prefix + "l" + longCount++);
            else if (type.equals(doubleType))
                l.setName(prefix + "d" + doubleCount++);
            else if (type.equals(floatType))
                l.setName(prefix + "f" + floatCount++);
            else if (type.equals(stmtAddressType))
                l.setName(prefix + "a" + addressCount++);
            else if (type.equals(erroneousType) || type.equals(unknownType)) {
                l.setName(prefix + "e" + errorCount++);
            } else if (type.equals(nullType))
                l.setName(prefix + "n" + nullCount++);
            else
                l.setName(prefix + "r" + objectCount++);
        }
    }
}

Example 7 with UnknownType

use of soot.UnknownType in project soot by Sable.

the class AbstractThrowAnalysis method mightThrowExplicitly.

public ThrowableSet mightThrowExplicitly(ThrowStmt t) {
    Value thrownExpression = t.getOp();
    Type thrownType = thrownExpression.getType();
    if (thrownType == null || thrownType instanceof UnknownType) {
        // We can't identify the type of thrownExpression, so...
        return ThrowableSet.Manager.v().ALL_THROWABLES;
    } else if (thrownType instanceof NullType) {
        ThrowableSet result = ThrowableSet.Manager.v().EMPTY;
        result = result.add(ThrowableSet.Manager.v().NULL_POINTER_EXCEPTION);
        return result;
    } else if (!(thrownType instanceof RefType)) {
        throw new IllegalStateException("UnitThrowAnalysis StmtSwitch: type of throw argument is not a RefType!");
    } else {
        ThrowableSet result = ThrowableSet.Manager.v().EMPTY;
        if (thrownExpression instanceof NewInvokeExpr) {
            // In this case, we know the exact type of the
            // argument exception.
            result = result.add((RefType) thrownType);
        } else {
            result = result.add(AnySubType.v((RefType) thrownType));
        }
        return result;
    }
}

Example 8 with UnknownType

use of soot.UnknownType in project soot by Sable.

the class SootASMClassWriterTest method setUp.

@Before
public void setUp() throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {
    mockStatic(Scene.class);
    mockStatic(RefType.class);
    mockStatic(UnknownType.class);
    scene = mock(Scene.class);
    when(Scene.v()).thenReturn(scene);
    UnknownType unknown = mock(UnknownType.class);
    when(UnknownType.v()).thenReturn(unknown);
    sc1 = mockClass("A");
    sc2 = mockClass("B");
    type1 = RefType.v("A");
    type2 = RefType.v("B");
    object = mockClass("java.lang.Object");
    objectType = mock(RefType.class);
    when(object.getType()).thenReturn(objectType);
    when(Scene.v().getObjectType()).thenReturn(objectType);
    when(objectType.getSootClass()).thenReturn(object);
    when(objectType.getClassName()).thenReturn("java.lang.Object");
    when(type1.merge(type2, scene)).thenCallRealMethod();
    commonSuperClass = mockClass("C");
    commonSuperClass.setResolvingLevel(SootClass.HIERARCHY);
    when(commonSuperClass.getSuperclass()).thenReturn(object);
    when(commonSuperClass.getSuperclassUnsafe()).thenReturn(object);
    cw = mock(SootASMClassWriter.class);
    when(cw.getCommonSuperClass("A", "B")).thenCallRealMethod();
}

Example 9 with UnknownType

use of soot.UnknownType in project soot by Sable.

the class DexBody method jimplify.

/**
 * Return the jimple equivalent of this body.
 *
 * @param m
 *            the SootMethod that contains this body
 */
public Body jimplify(Body b, SootMethod m) {
    final Jimple jimple = Jimple.v();
    final UnknownType unknownType = UnknownType.v();
    final NullConstant nullConstant = NullConstant.v();
    final Options options = Options.v();
    /*
		 * Timer t_whole_jimplification = new Timer(); Timer t_num = new
		 * Timer(); Timer t_null = new Timer();
		 * 
		 * t_whole_jimplification.start();
		 */
    jBody = (JimpleBody) b;
    deferredInstructions = new ArrayList<DeferableInstruction>();
    instructionsToRetype = new HashSet<RetypeableInstruction>();
    if (IDalvikTyper.ENABLE_DVKTYPER) {
        DalvikTyper.v().clear();
    }
    // process method parameters and generate Jimple locals from Dalvik
    // registers
    List<Local> paramLocals = new LinkedList<Local>();
    if (!isStatic) {
        int thisRegister = numRegisters - numParameterRegisters - 1;
        // generateLocal(UnknownType.v());
        Local thisLocal = jimple.newLocal("$u" + thisRegister, unknownType);
        jBody.getLocals().add(thisLocal);
        registerLocals[thisRegister] = thisLocal;
        JIdentityStmt idStmt = (JIdentityStmt) jimple.newIdentityStmt(thisLocal, jimple.newThisRef(declaringClassType));
        add(idStmt);
        paramLocals.add(thisLocal);
        if (IDalvikTyper.ENABLE_DVKTYPER) {
            DalvikTyper.v().setType(idStmt.leftBox, jBody.getMethod().getDeclaringClass().getType(), false);
        }
    }
    {
        // index of parameter type
        int i = 0;
        // index
        int parameterRegister = numRegisters - numParameterRegisters;
        // register
        for (Type t : parameterTypes) {
            // may
            Local gen = jimple.newLocal("$u" + parameterRegister, unknownType);
            // only
            // use
            // UnknownType
            // here
            // because
            // the
            // local
            // may
            // be
            // reused
            // with
            // a
            // different
            // type
            // later
            // (before
            // splitting)
            jBody.getLocals().add(gen);
            registerLocals[parameterRegister] = gen;
            JIdentityStmt idStmt = (JIdentityStmt) jimple.newIdentityStmt(gen, jimple.newParameterRef(t, i++));
            add(idStmt);
            paramLocals.add(gen);
            if (IDalvikTyper.ENABLE_DVKTYPER) {
                DalvikTyper.v().setType(idStmt.leftBox, t, false);
            }
            // used later in the Dalvik bytecode
            if (t instanceof LongType || t instanceof DoubleType) {
                parameterRegister++;
                // may
                Local g = jimple.newLocal("$u" + parameterRegister, unknownType);
                // only
                // use
                // UnknownType
                // here
                // because
                // the
                // local
                // may
                // be
                // reused
                // with
                // a
                // different
                // type
                // later
                // (before
                // splitting)
                jBody.getLocals().add(g);
                registerLocals[parameterRegister] = g;
            }
            parameterRegister++;
        }
    }
    for (int i = 0; i < (numRegisters - numParameterRegisters - (isStatic ? 0 : 1)); i++) {
        registerLocals[i] = jimple.newLocal("$u" + i, unknownType);
        jBody.getLocals().add(registerLocals[i]);
    }
    // add local to store intermediate results
    storeResultLocal = jimple.newLocal("$u-1", unknownType);
    jBody.getLocals().add(storeResultLocal);
    // process bytecode instructions
    final boolean isOdex = dexFile instanceof DexBackedDexFile ? ((DexBackedDexFile) dexFile).isOdexFile() : false;
    ClassPath cp = null;
    if (isOdex) {
        String[] sootClasspath = options.soot_classpath().split(File.pathSeparator);
        List<String> classpathList = new ArrayList<String>();
        for (String str : sootClasspath) classpathList.add(str);
        try {
            ClassPathResolver resolver = new ClassPathResolver(classpathList, classpathList, classpathList, dexFile);
            cp = new ClassPath(resolver.getResolvedClassProviders().toArray(new ClassProvider[0]));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
    int prevLineNumber = -1;
    for (DexlibAbstractInstruction instruction : instructions) {
        if (isOdex && instruction instanceof OdexInstruction)
            ((OdexInstruction) instruction).deOdex(dexFile, method, cp);
        if (dangling != null) {
            dangling.finalize(this, instruction);
            dangling = null;
        }
        instruction.jimplify(this);
        if (instruction.getLineNumber() > 0)
            prevLineNumber = instruction.getLineNumber();
        else {
            instruction.setLineNumber(prevLineNumber);
        }
    }
    for (DeferableInstruction instruction : deferredInstructions) {
        instruction.deferredJimplify(this);
    }
    if (tries != null)
        addTraps();
    int prevLn = -1;
    final boolean keepLineNumber = options.keep_line_number();
    for (DexlibAbstractInstruction instruction : instructions) {
        Unit unit = instruction.getUnit();
        int lineNumber = unit.getJavaSourceStartLineNumber();
        if (keepLineNumber && lineNumber < 0) {
            if (prevLn >= 0) {
                unit.addTag(new LineNumberTag(prevLn));
                unit.addTag(new SourceLineNumberTag(prevLn));
            }
        } else {
            prevLn = lineNumber;
        }
    }
    // At this point Jimple code is generated
    // Cleaning...
    instructions = null;
    // registerLocals = null;
    // storeResultLocal = null;
    instructionAtAddress.clear();
    // localGenerator = null;
    deferredInstructions = null;
    // instructionsToRetype = null;
    dangling = null;
    tries = null;
    /*
		 * We eliminate dead code. Dead code has been shown to occur under the
		 * following circumstances.
		 *
		 * 0006ec: 0d00 |00a2: move-exception v0 ... 0006f2: 0d00 |00a5:
		 * move-exception v0 ... 0x0041 - 0x008a Ljava/lang/Throwable; -> 0x00a5
		 * <any> -> 0x00a2
		 * 
		 * Here there are two traps both over the same region. But the same
		 * always fires, hence rendering the code at a2 unreachable. Dead code
		 * yields problems during local splitting because locals within dead
		 * code will not be split. Hence we remove all dead code here.
		 */
    // Fix traps that do not catch exceptions
    DexTrapStackFixer.v().transform(jBody);
    // Sort out jump chains
    DexJumpChainShortener.v().transform(jBody);
    // Make sure that we don't have any overlapping uses due to returns
    DexReturnInliner.v().transform(jBody);
    // Shortcut: Reduce array initializations
    DexArrayInitReducer.v().transform(jBody);
    // split first to find undefined uses
    getLocalSplitter().transform(jBody);
    // Remove dead code and the corresponding locals before assigning types
    getUnreachableCodeEliminator().transform(jBody);
    DeadAssignmentEliminator.v().transform(jBody);
    UnusedLocalEliminator.v().transform(jBody);
    for (RetypeableInstruction i : instructionsToRetype) i.retype(jBody);
    if (IDalvikTyper.ENABLE_DVKTYPER) {
        DexReturnValuePropagator.v().transform(jBody);
        getCopyPopagator().transform(jBody);
        DexNullThrowTransformer.v().transform(jBody);
        DalvikTyper.v().typeUntypedConstrantInDiv(jBody);
        DeadAssignmentEliminator.v().transform(jBody);
        UnusedLocalEliminator.v().transform(jBody);
        DalvikTyper.v().assignType(jBody);
        // jBody.validate();
        jBody.validateUses();
        jBody.validateValueBoxes();
    // jBody.checkInit();
    // Validate.validateArrays(jBody);
    // jBody.checkTypes();
    // jBody.checkLocals();
    } else {
        // t_num.start();
        DexNumTransformer.v().transform(jBody);
        // t_num.end();
        DexReturnValuePropagator.v().transform(jBody);
        getCopyPopagator().transform(jBody);
        DexNullThrowTransformer.v().transform(jBody);
        // t_null.start();
        DexNullTransformer.v().transform(jBody);
        // t_null.end();
        DexIfTransformer.v().transform(jBody);
        DeadAssignmentEliminator.v().transform(jBody);
        UnusedLocalEliminator.v().transform(jBody);
        // DexRefsChecker.v().transform(jBody);
        DexNullArrayRefTransformer.v().transform(jBody);
    }
    if (IDalvikTyper.ENABLE_DVKTYPER) {
        for (Local l : jBody.getLocals()) {
            l.setType(unknownType);
        }
    }
    // Remove "instanceof" checks on the null constant
    DexNullInstanceofTransformer.v().transform(jBody);
    TypeAssigner.v().transform(jBody);
    final RefType objectType = RefType.v("java.lang.Object");
    if (IDalvikTyper.ENABLE_DVKTYPER) {
        for (Unit u : jBody.getUnits()) {
            if (u instanceof IfStmt) {
                ConditionExpr expr = (ConditionExpr) ((IfStmt) u).getCondition();
                if (((expr instanceof EqExpr) || (expr instanceof NeExpr))) {
                    Value op1 = expr.getOp1();
                    Value op2 = expr.getOp2();
                    if (op1 instanceof Constant && op2 instanceof Local) {
                        Local l = (Local) op2;
                        Type ltype = l.getType();
                        if (ltype instanceof PrimType)
                            continue;
                        if (// by default
                        !(op1 instanceof IntConstant))
                            // in Dalvik
                            continue;
                        IntConstant icst = (IntConstant) op1;
                        int val = icst.value;
                        if (val != 0)
                            continue;
                        expr.setOp1(nullConstant);
                    } else if (op1 instanceof Local && op2 instanceof Constant) {
                        Local l = (Local) op1;
                        Type ltype = l.getType();
                        if (ltype instanceof PrimType)
                            continue;
                        if (// by default
                        !(op2 instanceof IntConstant))
                            // in Dalvik
                            continue;
                        IntConstant icst = (IntConstant) op2;
                        int val = icst.value;
                        if (val != 0)
                            continue;
                        expr.setOp2(nullConstant);
                    } else if (op1 instanceof Local && op2 instanceof Local) {
                    // nothing to do
                    } else if (op1 instanceof Constant && op2 instanceof Constant) {
                        if (op1 instanceof NullConstant && op2 instanceof NumericConstant) {
                            IntConstant nc = (IntConstant) op2;
                            if (nc.value != 0)
                                throw new RuntimeException("expected value 0 for int constant. Got " + expr);
                            expr.setOp2(NullConstant.v());
                        } else if (op2 instanceof NullConstant && op1 instanceof NumericConstant) {
                            IntConstant nc = (IntConstant) op1;
                            if (nc.value != 0)
                                throw new RuntimeException("expected value 0 for int constant. Got " + expr);
                            expr.setOp1(nullConstant);
                        }
                    } else {
                        throw new RuntimeException("error: do not handle if: " + u);
                    }
                }
            }
        }
        // For null_type locals: replace their use by NullConstant()
        List<ValueBox> uses = jBody.getUseBoxes();
        // List<ValueBox> defs = jBody.getDefBoxes();
        List<ValueBox> toNullConstantify = new ArrayList<ValueBox>();
        List<Local> toRemove = new ArrayList<Local>();
        for (Local l : jBody.getLocals()) {
            if (l.getType() instanceof NullType) {
                toRemove.add(l);
                for (ValueBox vb : uses) {
                    Value v = vb.getValue();
                    if (v == l)
                        toNullConstantify.add(vb);
                }
            }
        }
        for (ValueBox vb : toNullConstantify) {
            System.out.println("replace valuebox '" + vb + " with null constant");
            vb.setValue(nullConstant);
        }
        for (Local l : toRemove) {
            System.out.println("removing null_type local " + l);
            l.setType(objectType);
        }
    }
    // We pack locals that are not used in overlapping regions. This may
    // again lead to unused locals which we have to remove.
    LocalPacker.v().transform(jBody);
    UnusedLocalEliminator.v().transform(jBody);
    LocalNameStandardizer.v().transform(jBody);
    // on the fly.
    if (options.wrong_staticness() == Options.wrong_staticness_fix) {
        FieldStaticnessCorrector.v().transform(jBody);
        MethodStaticnessCorrector.v().transform(jBody);
    }
    // Inline PackManager.v().getPack("jb").apply(jBody);
    // Keep only transformations that have not been done
    // at this point.
    TrapTightener.v().transform(jBody);
    TrapMinimizer.v().transform(jBody);
    // LocalSplitter.v().transform(jBody);
    Aggregator.v().transform(jBody);
    // UnusedLocalEliminator.v().transform(jBody);
    // TypeAssigner.v().transform(jBody);
    // LocalPacker.v().transform(jBody);
    // LocalNameStandardizer.v().transform(jBody);
    // Remove if (null == null) goto x else <madness>. We can only do this
    // after we have run the constant propagation as we might not be able
    // to statically decide the conditions earlier.
    ConditionalBranchFolder.v().transform(jBody);
    // Remove unnecessary typecasts
    ConstantCastEliminator.v().transform(jBody);
    IdentityCastEliminator.v().transform(jBody);
    // Remove unnecessary logic operations
    IdentityOperationEliminator.v().transform(jBody);
    // We need to run this transformer since the conditional branch folder
    // might have rendered some code unreachable (well, it was unreachable
    // before as well, but we didn't know).
    UnreachableCodeEliminator.v().transform(jBody);
    // Not sure whether we need this even though we do it earlier on as
    // the earlier pass does not have type information
    // CopyPropagator.v().transform(jBody);
    // we might have gotten new dead assignments and unused locals through
    // copy propagation and unreachable code elimination, so we have to do
    // this again
    DeadAssignmentEliminator.v().transform(jBody);
    UnusedLocalEliminator.v().transform(jBody);
    NopEliminator.v().transform(jBody);
    // Remove unnecessary chains of return statements
    DexReturnPacker.v().transform(jBody);
    for (Unit u : jBody.getUnits()) {
        if (u instanceof AssignStmt) {
            AssignStmt ass = (AssignStmt) u;
            if (ass.getRightOp() instanceof CastExpr) {
                CastExpr c = (CastExpr) ass.getRightOp();
                if (c.getType() instanceof NullType) {
                    ass.setRightOp(nullConstant);
                }
            }
        }
        if (u instanceof DefinitionStmt) {
            DefinitionStmt def = (DefinitionStmt) u;
            // we must manually fix the hierarchy
            if (def.getLeftOp() instanceof Local && def.getRightOp() instanceof CaughtExceptionRef) {
                Type t = def.getLeftOp().getType();
                if (t instanceof RefType) {
                    RefType rt = (RefType) t;
                    if (rt.getSootClass().isPhantom() && !rt.getSootClass().hasSuperclass() && !rt.getSootClass().getName().equals("java.lang.Throwable"))
                        rt.getSootClass().setSuperclass(Scene.v().getSootClass("java.lang.Throwable"));
                }
            }
        }
    }
    // 
    for (Local l : jBody.getLocals()) {
        Type t = l.getType();
        if (t instanceof NullType) {
            l.setType(objectType);
        }
    }
    return jBody;
}

Example 10 with UnknownType

use of soot.UnknownType in project soot by Sable.

the class DexIfTransformer method internalTransform.

@Override
protected void internalTransform(final Body body, String phaseName, Map<String, String> options) {
    final DexDefUseAnalysis localDefs = new DexDefUseAnalysis(body);
    Set<IfStmt> ifSet = getNullIfCandidates(body);
    for (IfStmt ifs : ifSet) {
        ConditionExpr ifCondition = (ConditionExpr) ifs.getCondition();
        Local[] twoIfLocals = new Local[] { (Local) ifCondition.getOp1(), (Local) ifCondition.getOp2() };
        usedAsObject = false;
        for (Local loc : twoIfLocals) {
            Set<Unit> defs = localDefs.collectDefinitionsWithAliases(loc);
            // process normally
            doBreak = false;
            for (Unit u : defs) {
                // put correct local in l
                if (u instanceof DefinitionStmt) {
                    l = (Local) ((DefinitionStmt) u).getLeftOp();
                } else {
                    throw new RuntimeException("ERROR: def can not be something else than Assign or Identity statement! (def: " + u + " class: " + u.getClass() + "");
                }
                // check defs
                u.apply(new // Alex: should also end
                AbstractStmtSwitch() {

                    // as soon as detected
                    // as not used as an
                    // object
                    @Override
                    public void caseAssignStmt(AssignStmt stmt) {
                        Value r = stmt.getRightOp();
                        if (r instanceof FieldRef) {
                            usedAsObject = isObject(((FieldRef) r).getFieldRef().type());
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        } else if (r instanceof ArrayRef) {
                            ArrayRef ar = (ArrayRef) r;
                            if (ar.getType() instanceof UnknownType) {
                                // isObject
                                usedAsObject = stmt.hasTag("ObjectOpTag");
                            // (findArrayType
                            // (g,
                            // localDefs,
                            // localUses,
                            // stmt));
                            } else {
                                usedAsObject = isObject(ar.getType());
                            }
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        } else if (r instanceof StringConstant || r instanceof NewExpr || r instanceof NewArrayExpr) {
                            usedAsObject = true;
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        } else if (r instanceof CastExpr) {
                            usedAsObject = isObject(((CastExpr) r).getCastType());
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        } else if (r instanceof InvokeExpr) {
                            usedAsObject = isObject(((InvokeExpr) r).getType());
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        } else if (r instanceof LengthExpr) {
                            usedAsObject = false;
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        }
                    }

                    @Override
                    public void caseIdentityStmt(IdentityStmt stmt) {
                        if (stmt.getLeftOp() == l) {
                            usedAsObject = isObject(stmt.getRightOp().getType());
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        }
                    }
                });
                if (doBreak)
                    break;
                // check uses
                for (Unit use : localDefs.getUsesOf(l)) {
                    use.apply(new AbstractStmtSwitch() {

                        private boolean examineInvokeExpr(InvokeExpr e) {
                            List<Value> args = e.getArgs();
                            List<Type> argTypes = e.getMethodRef().parameterTypes();
                            assert args.size() == argTypes.size();
                            for (int i = 0; i < args.size(); i++) {
                                if (args.get(i) == l && isObject(argTypes.get(i))) {
                                    return true;
                                }
                            }
                            // check for base
                            SootMethodRef sm = e.getMethodRef();
                            if (!sm.isStatic()) {
                                if (e instanceof AbstractInvokeExpr) {
                                    AbstractInstanceInvokeExpr aiiexpr = (AbstractInstanceInvokeExpr) e;
                                    Value b = aiiexpr.getBase();
                                    if (b == l) {
                                        return true;
                                    }
                                }
                            }
                            return false;
                        }

                        @Override
                        public void caseInvokeStmt(InvokeStmt stmt) {
                            InvokeExpr e = stmt.getInvokeExpr();
                            usedAsObject = examineInvokeExpr(e);
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        }

                        @Override
                        public void caseAssignStmt(AssignStmt stmt) {
                            Value left = stmt.getLeftOp();
                            Value r = stmt.getRightOp();
                            if (left instanceof ArrayRef) {
                                if (((ArrayRef) left).getIndex() == l) {
                                    // doBreak = true;
                                    return;
                                }
                            }
                            // used to assign
                            if (stmt.getRightOp() == l) {
                                Value l = stmt.getLeftOp();
                                if (l instanceof StaticFieldRef && isObject(((StaticFieldRef) l).getFieldRef().type())) {
                                    usedAsObject = true;
                                    if (usedAsObject)
                                        doBreak = true;
                                    return;
                                } else if (l instanceof InstanceFieldRef && isObject(((InstanceFieldRef) l).getFieldRef().type())) {
                                    usedAsObject = true;
                                    if (usedAsObject)
                                        doBreak = true;
                                    return;
                                } else if (l instanceof ArrayRef) {
                                    Type aType = ((ArrayRef) l).getType();
                                    if (aType instanceof UnknownType) {
                                        // isObject(
                                        usedAsObject = stmt.hasTag("ObjectOpTag");
                                    // findArrayType(g,
                                    // localDefs,
                                    // localUses,
                                    // stmt));
                                    } else {
                                        usedAsObject = isObject(aType);
                                    }
                                    if (usedAsObject)
                                        doBreak = true;
                                    return;
                                }
                            }
                            // assignment)
                            if (r instanceof FieldRef) {
                                // isObject(((FieldRef)
                                usedAsObject = true;
                                // r).getFieldRef().type());
                                if (usedAsObject)
                                    doBreak = true;
                                return;
                            } else if (r instanceof ArrayRef) {
                                ArrayRef ar = (ArrayRef) r;
                                if (ar.getBase() == l) {
                                    usedAsObject = true;
                                } else {
                                    // used as index
                                    usedAsObject = false;
                                }
                                if (usedAsObject)
                                    doBreak = true;
                                return;
                            } else if (r instanceof StringConstant || r instanceof NewExpr) {
                                throw new RuntimeException("NOT POSSIBLE StringConstant or NewExpr at " + stmt);
                            } else if (r instanceof NewArrayExpr) {
                                usedAsObject = false;
                                if (usedAsObject)
                                    doBreak = true;
                                return;
                            } else if (r instanceof CastExpr) {
                                usedAsObject = isObject(((CastExpr) r).getCastType());
                                if (usedAsObject)
                                    doBreak = true;
                                return;
                            } else if (r instanceof InvokeExpr) {
                                usedAsObject = examineInvokeExpr((InvokeExpr) stmt.getRightOp());
                                if (usedAsObject)
                                    doBreak = true;
                                return;
                            } else if (r instanceof LengthExpr) {
                                usedAsObject = true;
                                if (usedAsObject)
                                    doBreak = true;
                                return;
                            } else if (r instanceof BinopExpr) {
                                usedAsObject = false;
                                if (usedAsObject)
                                    doBreak = true;
                                return;
                            }
                        }

                        @Override
                        public void caseIdentityStmt(IdentityStmt stmt) {
                            if (stmt.getLeftOp() == l)
                                throw new RuntimeException("IMPOSSIBLE 0");
                        }

                        @Override
                        public void caseEnterMonitorStmt(EnterMonitorStmt stmt) {
                            usedAsObject = stmt.getOp() == l;
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        }

                        @Override
                        public void caseExitMonitorStmt(ExitMonitorStmt stmt) {
                            usedAsObject = stmt.getOp() == l;
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        }

                        @Override
                        public void caseReturnStmt(ReturnStmt stmt) {
                            usedAsObject = stmt.getOp() == l && isObject(body.getMethod().getReturnType());
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        }

                        @Override
                        public void caseThrowStmt(ThrowStmt stmt) {
                            usedAsObject = stmt.getOp() == l;
                            if (usedAsObject)
                                doBreak = true;
                            return;
                        }
                    });
                    if (doBreak)
                        break;
                }
                // for uses
                if (doBreak)
                    break;
            }
            if (// as soon as one def or use refers to an object
            doBreak)
                // be updated
                break;
        }
        // change values
        if (usedAsObject) {
            Set<Unit> defsOp1 = localDefs.collectDefinitionsWithAliases(twoIfLocals[0]);
            Set<Unit> defsOp2 = localDefs.collectDefinitionsWithAliases(twoIfLocals[1]);
            defsOp1.addAll(defsOp2);
            for (Unit u : defsOp1) {
                Stmt s = (Stmt) u;
                // If we have a[x] = 0 and a is an object, we may not conclude 0 -> null
                if (!s.containsArrayRef() || (!defsOp1.contains(s.getArrayRef().getBase()) && !defsOp2.contains(s.getArrayRef().getBase())))
                    replaceWithNull(u);
                Local l = (Local) ((DefinitionStmt) u).getLeftOp();
                for (Unit uuse : localDefs.getUsesOf(l)) {
                    Stmt use = (Stmt) uuse;
                    // If we have a[x] = 0 and a is an object, we may not conclude 0 -> null
                    if (!use.containsArrayRef() || (twoIfLocals[0] != use.getArrayRef().getBase()) && twoIfLocals[1] != use.getArrayRef().getBase())
                        replaceWithNull(use);
                }
            }
        }
    // end if
    }
// for if statements
}