/**
* If this is a putfield or putstatic instruction, check to see if the field is @NonNull, and
* treat it as dereferences.
*
* @param location the Location of the instruction
* @param vnaFrame the ValueNumberFrame at the Location of the instruction
* @param fact the dataflow value to modify
* @throws DataflowAnalysisException
*/
private void checkNonNullPutField(
Location location, ValueNumberFrame vnaFrame, UnconditionalValueDerefSet fact)
throws DataflowAnalysisException {
INullnessAnnotationDatabase database =
AnalysisContext.currentAnalysisContext().getNullnessAnnotationDatabase();
FieldInstruction fieldIns = (FieldInstruction) location.getHandle().getInstruction();
XField field = XFactory.createXField(fieldIns, methodGen.getConstantPool());
char firstChar = field.getSignature().charAt(0);
if (firstChar != 'L' && firstChar != '[') {
return;
}
NullnessAnnotation resolvedAnnotation = database.getResolvedAnnotation(field, true);
if (resolvedAnnotation == NullnessAnnotation.NONNULL) {
IsNullValueFrame invFrame = invDataflow.getFactAtLocation(location);
if (!invFrame.isValid()) {
return;
}
IsNullValue value = invFrame.getTopValue();
if (reportDereference(value)) {
ValueNumber vn = vnaFrame.getTopValue();
fact.addDeref(vn, location);
}
}
}
public static Set<ValueNumber> checkNonNullParams(
Location location,
ValueNumberFrame vnaFrame,
ConstantPoolGen constantPool,
@CheckForNull Method method,
@CheckForNull IsNullValueFrame invFrame)
throws DataflowAnalysisException {
if (invFrame != null && !invFrame.isValid()) {
return Collections.emptySet();
}
INullnessAnnotationDatabase database =
AnalysisContext.currentAnalysisContext().getNullnessAnnotationDatabase();
InvokeInstruction inv = (InvokeInstruction) location.getHandle().getInstruction();
XMethod called = XFactory.createXMethod(inv, constantPool);
SignatureParser sigParser = new SignatureParser(called.getSignature());
int numParams = sigParser.getNumParameters();
Set<ValueNumber> result = new HashSet<ValueNumber>();
Iterator<String> parameterIterator = sigParser.parameterSignatureIterator();
for (int i = 0; i < numParams; i++) {
String parameterSignature = parameterIterator.next();
char firstChar = parameterSignature.charAt(0);
if (firstChar != 'L' && firstChar != '[') {
continue;
}
int offset = sigParser.getSlotsFromTopOfStackForParameter(i);
if (invFrame != null) {
int slot = invFrame.getStackLocation(offset);
if (!reportDereference(invFrame, slot)) {
continue;
}
}
if (database.parameterMustBeNonNull(called, i)) {
int catchSizeNPE =
Util.getSizeOfSurroundingTryBlock(
method, "java/lang/NullPointerException", location.getHandle().getPosition());
int catchSizeNFE =
Util.getSizeOfSurroundingTryBlock(
method, "java/lang/NumberFormatException", location.getHandle().getPosition());
if (catchSizeNPE == Integer.MAX_VALUE
&& (!"java.lang.Integer".equals(called.getClassName())
|| catchSizeNFE == Integer.MAX_VALUE)) {
// Get the corresponding value number
ValueNumber vn = vnaFrame.getArgument(inv, constantPool, i, sigParser);
result.add(vn);
}
}
}
return result;
}
public static boolean reportPotentialDereference(Location location, IsNullValueFrame invFrame)
throws DataflowAnalysisException {
if (!invFrame.isValid()) {
return false;
}
IsNullValue value = invFrame.getTopValue();
if (value.isDefinitelyNotNull()) {
return false;
}
if (value.isDefinitelyNull()) {
return false;
}
return true;
}
/**
* Clear deref sets of values if this edge is the non-null branch of an if comparison.
*
* @param fact a datflow fact
* @param edge edge to check
* @return possibly-modified dataflow fact
*/
private @CheckForNull ValueNumber findValueKnownNonnullOnBranch(
UnconditionalValueDerefSet fact, Edge edge) {
IsNullValueFrame invFrame = invDataflow.getResultFact(edge.getSource());
if (!invFrame.isValid()) {
return null;
}
IsNullConditionDecision decision = invFrame.getDecision();
if (decision == null) {
return null;
}
IsNullValue inv = decision.getDecision(edge.getType());
if (inv == null || !inv.isDefinitelyNotNull()) {
return null;
}
ValueNumber value = decision.getValue();
if (DEBUG) {
System.out.println("Value number " + value + " is known nonnull on " + edge);
}
return value;
}
private static boolean reportDereference(IsNullValueFrame invFrameAtNullCheck, int instance) {
return reportDereference(invFrameAtNullCheck.getValue(instance));
}
/**
* Check to see if the instruction has a null check associated with it, and if so, add a
* dereference.
*
* @param location the Location of the instruction
* @param vnaFrame ValueNumberFrame at the Location of the instruction
* @param fact the dataflow value to modify
* @throws DataflowAnalysisException
*/
private void checkInstance(
Location location, ValueNumberFrame vnaFrame, UnconditionalValueDerefSet fact)
throws DataflowAnalysisException {
// See if this instruction has a null check.
// If it does, the fall through predecessor will be
// identify itself as the null check.
if (!location.isFirstInstructionInBasicBlock()) {
return;
}
if (invDataflow == null) {
return;
}
BasicBlock fallThroughPredecessor =
cfg.getPredecessorWithEdgeType(location.getBasicBlock(), EdgeTypes.FALL_THROUGH_EDGE);
if (fallThroughPredecessor == null || !fallThroughPredecessor.isNullCheck()) {
return;
}
// Get the null-checked value
ValueNumber vn =
vnaFrame.getInstance(location.getHandle().getInstruction(), methodGen.getConstantPool());
// Ignore dereferences of this
if (!methodGen.isStatic()) {
ValueNumber v = vnaFrame.getValue(0);
if (v.equals(vn)) {
return;
}
}
if (vn.hasFlag(ValueNumber.CONSTANT_CLASS_OBJECT)) {
return;
}
IsNullValueFrame startFact = null;
startFact = invDataflow.getStartFact(fallThroughPredecessor);
if (!startFact.isValid()) {
return;
}
int slot =
startFact.getInstanceSlot(
location.getHandle().getInstruction(), methodGen.getConstantPool());
if (!reportDereference(startFact, slot)) {
return;
}
if (DEBUG) {
System.out.println("FOUND GUARANTEED DEREFERENCE");
System.out.println("Load: " + vnaFrame.getLoad(vn));
System.out.println("Pred: " + fallThroughPredecessor);
System.out.println("startFact: " + startFact);
System.out.println("Location: " + location);
System.out.println("Value number frame: " + vnaFrame);
System.out.println("Dereferenced valueNumber: " + vn);
System.out.println("invDataflow: " + startFact);
System.out.println("IGNORE_DEREF_OF_NCP: " + IGNORE_DEREF_OF_NCP);
}
// Mark the value number as being dereferenced at this location
fact.addDeref(vn, location);
}
public static Set<ValueNumber> checkUnconditionalDerefDatabase(
Location location,
ValueNumberFrame vnaFrame,
ConstantPoolGen constantPool,
@CheckForNull IsNullValueFrame invFrame,
TypeDataflow typeDataflow)
throws DataflowAnalysisException {
if (invFrame != null && !invFrame.isValid()) {
return Collections.emptySet();
}
InvokeInstruction inv = (InvokeInstruction) location.getHandle().getInstruction();
SignatureParser sigParser = new SignatureParser(inv.getSignature(constantPool));
int numParams = sigParser.getNumParameters();
if (numParams == 0 || !sigParser.hasReferenceParameters()) {
return Collections.emptySet();
}
ParameterNullnessPropertyDatabase database =
AnalysisContext.currentAnalysisContext().getUnconditionalDerefParamDatabase();
if (database == null) {
if (DEBUG_CHECK_CALLS) {
System.out.println("no database!");
}
return Collections.emptySet();
}
TypeFrame typeFrame = typeDataflow.getFactAtLocation(location);
if (!typeFrame.isValid()) {
if (DEBUG_CHECK_CALLS) {
System.out.println("invalid type frame!");
}
return Collections.emptySet();
}
try {
Set<XMethod> targetSet = Hierarchy2.resolveMethodCallTargets(inv, typeFrame, constantPool);
if (targetSet.isEmpty()) {
return Collections.emptySet();
}
if (DEBUG_CHECK_CALLS) {
System.out.println("target set size: " + targetSet.size());
}
// Compute the intersection of all properties
ParameterProperty derefParamSet = null;
for (XMethod target : targetSet) {
if (target.isStub()) {
continue;
}
if (DEBUG_CHECK_CALLS) {
System.out.print("Checking: " + target + ": ");
}
ParameterProperty targetDerefParamSet = database.getProperty(target.getMethodDescriptor());
if (targetDerefParamSet == null) {
// Hmm...no information for this target.
// assume it doesn't dereference anything
if (DEBUG_CHECK_CALLS) {
System.out.println("==> no information, assume no guaranteed dereferences");
}
return Collections.emptySet();
}
if (DEBUG_CHECK_CALLS) {
System.out.println("==> " + targetDerefParamSet);
}
if (derefParamSet == null) {
derefParamSet = new ParameterProperty();
derefParamSet.copyFrom(targetDerefParamSet);
} else {
derefParamSet.intersectWith(targetDerefParamSet);
}
}
if (derefParamSet == null || derefParamSet.isEmpty()) {
if (DEBUG) {
System.out.println("** Nothing");
}
return Collections.emptySet();
}
if (DEBUG_CHECK_CALLS) {
System.out.println(
"** Summary of call @ " + location.getHandle().getPosition() + ": " + derefParamSet);
}
HashSet<ValueNumber> requiredToBeNonnull = new HashSet<ValueNumber>();
for (int i = 0; i < numParams; i++) {
if (!derefParamSet.hasProperty(i)) {
continue;
}
int argSlot = vnaFrame.getStackLocation(sigParser.getSlotsFromTopOfStackForParameter(i));
if (invFrame != null && !reportDereference(invFrame, argSlot)) {
continue;
}
if (DEBUG_CHECK_CALLS) {
System.out.println(
" dereference @ " + location.getHandle().getPosition() + " of parameter " + i);
}
requiredToBeNonnull.add(vnaFrame.getValue(argSlot));
}
return requiredToBeNonnull;
} catch (ClassNotFoundException e) {
AnalysisContext.reportMissingClass(e);
}
return Collections.emptySet();
}
