@Override
public void transferInstruction(InstructionHandle handle, BasicBlock basicBlock, LockSet fact)
throws DataflowAnalysisException {
Instruction ins = handle.getInstruction();
short opcode = ins.getOpcode();
if (opcode == Constants.MONITORENTER || opcode == Constants.MONITOREXIT) {
ValueNumberFrame frame = vnaDataflow.getFactAtLocation(new Location(handle, basicBlock));
modifyLock(frame, fact, opcode == Constants.MONITORENTER ? 1 : -1);
} else if (opcode == Constants.INVOKEVIRTUAL || opcode == Constants.INVOKEINTERFACE) {
InvokeInstruction inv = (InvokeInstruction) ins;
String name = inv.getMethodName(methodGen.getConstantPool());
String sig = inv.getSignature(methodGen.getConstantPool());
ValueNumberFrame frame = vnaDataflow.getFactAtLocation(new Location(handle, basicBlock));
if ("()V".equals(sig) && ("lock".equals(name) || "lockInterruptibly".equals(name))) {
modifyLock(frame, fact, 1);
} else if ("()V".equals(sig) && ("unlock".equals(name))) {
modifyLock(frame, fact, -1);
}
} else if ((ins instanceof ReturnInstruction) && isSynchronized && !isStatic) {
lockOp(fact, vna.getThisValue().getNumber(), -1);
}
}
public LockAnalysis(MethodGen methodGen, ValueNumberDataflow vnaDataflow, DepthFirstSearch dfs) {
super(dfs);
this.methodGen = methodGen;
this.vnaDataflow = vnaDataflow;
this.vna = vnaDataflow.getAnalysis();
this.isSynchronized = methodGen.isSynchronized();
this.isStatic = methodGen.isStatic();
if (DEBUG) {
System.out.println(
"Analyzing Locks in " + methodGen.getClassName() + "." + methodGen.getName());
}
}
/**
* Find out if any VNs in the source block contribute to unconditionally dereferenced VNs in the
* target block. If so, the VN in the source block is also unconditionally dereferenced, and we
* must propagate the target VN's dereferences.
*
* @param fact a dataflow value
* @param edge edge to check for merge input values
* @return possibly-modified dataflow value
*/
private UnconditionalValueDerefSet propagateDerefSetsToMergeInputValues(
UnconditionalValueDerefSet fact, Edge edge) {
ValueNumberFrame blockValueNumberFrame = vnaDataflow.getResultFact(edge.getSource());
ValueNumberFrame targetValueNumberFrame = vnaDataflow.getStartFact(edge.getTarget());
UnconditionalValueDerefSet originalFact = fact;
fact = duplicateFact(fact);
if (blockValueNumberFrame.isValid() && targetValueNumberFrame.isValid()) {
int slots = 0;
if (targetValueNumberFrame.getNumSlots() == blockValueNumberFrame.getNumSlots()) {
slots = targetValueNumberFrame.getNumSlots();
} else if (targetValueNumberFrame.getNumLocals() == blockValueNumberFrame.getNumLocals()) {
slots = targetValueNumberFrame.getNumLocals();
}
if (slots > 0) {
if (DEBUG) {
System.out.println("** Valid VNA frames for " + edge);
System.out.println("** Block : " + blockValueNumberFrame);
System.out.println("** Target: " + targetValueNumberFrame);
}
for (int i = 0; i < slots; i++) {
ValueNumber blockVN = blockValueNumberFrame.getValue(i);
ValueNumber targetVN = targetValueNumberFrame.getValue(i);
if (blockVN.equals(targetVN)) {
continue;
}
fact.clearDerefSet(blockVN);
if (originalFact.isUnconditionallyDereferenced(targetVN)) {
fact.setDerefSet(blockVN, originalFact.getUnconditionalDerefLocationSet(targetVN));
}
} // for all slots
for (ValueNumber blockVN : blockValueNumberFrame.valueNumbersForLoads()) {
AvailableLoad load = blockValueNumberFrame.getLoad(blockVN);
if (load == null) {
continue;
}
ValueNumber[] targetVNs = targetValueNumberFrame.getAvailableLoad(load);
if (targetVNs != null) {
for (ValueNumber targetVN : targetVNs) {
if (targetVN.hasFlag(ValueNumber.PHI_NODE)
&& fact.isUnconditionallyDereferenced(targetVN)
&& !fact.isUnconditionallyDereferenced(blockVN)) {
// Block VN is also dereferenced
// unconditionally.
AvailableLoad targetLoad = targetValueNumberFrame.getLoad(targetVN);
if (!load.equals(targetLoad)) {
continue;
}
if (DEBUG) {
System.out.println(
"** Copy vn derefs for " + load + " from " + targetVN + " --> " + blockVN);
System.out.println(
"** block phi for "
+ System.identityHashCode(blockValueNumberFrame)
+ " is "
+ blockValueNumberFrame.phiNodeForLoads);
System.out.println(
"** target phi for "
+ System.identityHashCode(targetValueNumberFrame)
+ " is "
+ targetValueNumberFrame.phiNodeForLoads);
}
fact.setDerefSet(blockVN, fact.getUnconditionalDerefLocationSet(targetVN));
}
}
}
}
}
}
if (DEBUG) {
System.out.println("Target VNF: " + targetValueNumberFrame);
System.out.println("Block VNF: " + blockValueNumberFrame);
System.out.println("fact: " + fact);
}
fact.cleanDerefSet(null, blockValueNumberFrame);
return fact;
}
public void meetInto(
UnconditionalValueDerefSet fact,
Edge edge,
UnconditionalValueDerefSet result,
boolean onlyEdge) {
if (isExceptionEdge(edge) && !onlyEdge) {
if (DEBUG) {
System.out.println("Skipping exception edge");
}
return;
}
ValueNumber knownNonnullOnBranch = null;
// Edge transfer function
if (isFactValid(fact)) {
fact = propagateDerefSetsToMergeInputValues(fact, edge);
if (invDataflow != null) {
knownNonnullOnBranch = findValueKnownNonnullOnBranch(fact, edge);
if (knownNonnullOnBranch != null) {
fact = duplicateFact(fact);
fact.clearDerefSet(knownNonnullOnBranch);
}
}
}
boolean isBackEdge = edge.isBackwardInBytecode();
Set<Integer> loopExitBranches = ClassContext.getLoopExitBranches(method, methodGen);
assert loopExitBranches != null;
boolean sourceIsTopOfLoop = edge.sourceIsTopOfLoop(loopExitBranches);
if (sourceIsTopOfLoop && edge.getType() == EdgeTypes.FALL_THROUGH_EDGE) {
isBackEdge = true;
}
/*
if (false && (edge.getType() == EdgeTypes.IFCMP_EDGE || sourceIsTopOfLoop)) {
System.out.println("Meet into " + edge);
System.out.println(" foo2: " + sourceIsTopOfLoop);
System.out.println(" getType: " + edge.getType());
System.out.println(" Backedge according to bytecode: " + isBackEdge);
System.out.println(" Fact hashCode: " + System.identityHashCode(result));
System.out.println(" Initial fact: " + result);
System.out.println(" Edge fact: " + fact);
}
*/
if (result.isTop() || fact.isBottom()) {
// Make result identical to other fact
copy(fact, result);
if (ASSUME_NONZERO_TRIP_LOOPS && isBackEdge && !fact.isTop()) {
result.resultsFromBackEdge = true;
}
} else if (ASSUME_NONZERO_TRIP_LOOPS && isBackEdge && !fact.isTop()) {
result.unionWith(fact, vnaDataflow.getAnalysis().getFactory());
result.resultsFromBackEdge = true;
if (DEBUG) {
System.out.println(
"\n Forcing union of " + System.identityHashCode(result) + " due to backedge info");
System.out.println(" result: " + result);
}
} else if (result.isBottom() || fact.isTop()) {
// No change in result fact
} else {
// Dataflow merge
// (intersection of unconditional deref values)
if (ASSUME_NONZERO_TRIP_LOOPS && result.resultsFromBackEdge) {
result.backEdgeUpdateCount++;
if (result.backEdgeUpdateCount < 10) {
if (DEBUG) {
System.out.println(
"\n Union update of " + System.identityHashCode(result) + " due to backedge info");
}
result.unionWith(fact, vnaDataflow.getAnalysis().getFactory());
return;
}
}
result.mergeWith(fact, knownNonnullOnBranch, vnaDataflow.getAnalysis().getFactory());
if (DEBUG) {
System.out.println(" updated: " + System.identityHashCode(result));
System.out.println(" result: " + result);
}
}
if (DEBUG && isBackEdge && edge.getType() == EdgeTypes.IFCMP_EDGE) {
System.out.println(" result: " + result);
}
}
@Override
public UnconditionalValueDerefSet createFact() {
return new UnconditionalValueDerefSet(vnaDataflow.getAnalysis().getNumValuesAllocated());
}
@Override
public void transferInstruction(
InstructionHandle handle, BasicBlock basicBlock, UnconditionalValueDerefSet fact)
throws DataflowAnalysisException {
Instruction instruction = handle.getInstruction();
if (fact.isTop()) {
return;
}
Location location = new Location(handle, basicBlock);
// If this is a call to an assertion method,
// change the dataflow value to be TOP.
// We don't want to report future derefs that would
// be guaranteed only if the assertion methods
// returns normally.
// TODO: at some point, evaluate whether we should revisit this
if (isAssertion(handle) // || handle.getInstruction() instanceof ATHROW
) {
if (DEBUG) {
System.out.println("MAKING BOTTOM0 AT: " + location);
}
fact.clear();
return;
}
// Get value number frame
ValueNumberFrame vnaFrame = vnaDataflow.getFactAtLocation(location);
if (!vnaFrame.isValid()) {
if (DEBUG) {
System.out.println("MAKING TOP1 AT: " + location);
}
// Probably dead code.
// Assume this location can't be reached.
makeFactTop(fact);
return;
}
if (isNullCheck(handle, methodGen.getConstantPool())) {
handleNullCheck(location, vnaFrame, fact);
}
// Check for calls to a method that unconditionally dereferences
// a parameter. Mark any such arguments as derefs.
if (CHECK_CALLS && instruction instanceof InvokeInstruction) {
checkUnconditionalDerefDatabase(location, vnaFrame, fact);
}
// If this is a method call instruction,
// check to see if any of the parameters are @NonNull,
// and treat them as dereferences.
if (CHECK_ANNOTATIONS && instruction instanceof InvokeInstruction) {
checkNonNullParams(location, vnaFrame, fact);
}
if (CHECK_ANNOTATIONS && instruction instanceof ARETURN) {
XMethod thisMethod = XFactory.createXMethod(methodGen);
checkNonNullReturnValue(thisMethod, location, vnaFrame, fact);
}
if (CHECK_ANNOTATIONS
&& (instruction instanceof PUTFIELD || instruction instanceof PUTSTATIC)) {
checkNonNullPutField(location, vnaFrame, fact);
}
// Check to see if an instance value is dereferenced here
checkInstance(location, vnaFrame, fact);
/*
if (false) {
fact.cleanDerefSet(location, vnaFrame);
}*/
if (DEBUG && fact.isTop()) {
System.out.println("MAKING TOP2 At: " + location);
}
}
private void analyzeMethod(ClassContext classContext, Method method)
throws CFGBuilderException, DataflowAnalysisException {
if (isSynthetic(method) || !prescreen(classContext, method)) return;
XMethod xmethod = XFactory.createXMethod(classContext.getJavaClass(), method);
if (xmethod.isSynthetic()) return;
BugAccumulator accumulator = new BugAccumulator(bugReporter);
CFG cfg = classContext.getCFG(method);
TypeDataflow typeDataflow = classContext.getTypeDataflow(method);
ValueNumberDataflow vnDataflow = classContext.getValueNumberDataflow(method);
ConstantPoolGen cpg = classContext.getConstantPoolGen();
MethodGen methodGen = classContext.getMethodGen(method);
if (methodGen == null) return;
String fullMethodName = methodGen.getClassName() + "." + methodGen.getName();
String sourceFile = classContext.getJavaClass().getSourceFileName();
if (DEBUG) {
System.out.println("\n" + fullMethodName);
}
// Process each instruction
for (Iterator<Location> iter = cfg.locationIterator(); iter.hasNext(); ) {
Location location = iter.next();
InstructionHandle handle = location.getHandle();
Instruction ins = handle.getInstruction();
// Only consider invoke instructions
if (!(ins instanceof InvokeInstruction)) continue;
InvokeInstruction inv = (InvokeInstruction) ins;
XMethod invokedMethod = XFactory.createXMethod(inv, cpg);
String invokedMethodName = invokedMethod.getName();
String argSignature = invokedMethod.getSignature();
argSignature = argSignature.substring(0, argSignature.indexOf(')') + 1);
String call = invokedMethodName + argSignature;
SignatureParser sigParser = new SignatureParser(inv.getSignature(cpg));
Collection<Info> collection = callMap.get(call);
if (!callMap.containsKey(call)) continue;
for (Info info : collection) {
Subtypes2 subtypes2 = AnalysisContext.currentAnalysisContext().getSubtypes2();
if (DEBUG)
System.out.println(
"at "
+ handle.getPosition()
+ " Checking call to "
+ info.interfaceForCall
+ " : "
+ invokedMethod);
try {
if (!subtypes2.isSubtype(invokedMethod.getClassDescriptor(), info.interfaceForCall))
continue;
} catch (ClassNotFoundException e) {
if (info.interfaceForCall.getClassName().equals("java/util/Collection")
&& invokedMethod.getClassName().equals("com.google.common.collect.Multiset")) {
assert true;
// we know this is OK without needing to find definition of Multiset
} else {
AnalysisContext.reportMissingClass(e);
continue;
}
}
boolean allMethod;
int typeArgument;
if (info.typeIndex >= 0) {
allMethod = false;
typeArgument = info.typeIndex;
} else {
allMethod = true;
typeArgument = -(1 + info.typeIndex);
}
int pos = info.argumentIndex;
int lhsPos;
if (inv instanceof INVOKESTATIC) lhsPos = sigParser.getSlotsFromTopOfStackForParameter(0);
else lhsPos = sigParser.getTotalArgumentSize();
int stackPos = sigParser.getSlotsFromTopOfStackForParameter(pos);
TypeFrame frame = typeDataflow.getFactAtLocation(location);
if (!frame.isValid()) {
// This basic block is probably dead
continue;
}
Type operandType = frame.getStackValue(stackPos);
if (operandType.equals(TopType.instance())) {
// unreachable
continue;
}
if (operandType.equals(NullType.instance())) {
// ignore
continue;
}
ValueNumberFrame vnFrame = vnDataflow.getFactAtLocation(location);
if (!vnFrame.isValid()) {
AnalysisContext.logError("Invalid value number frame in " + xmethod);
continue;
}
ValueNumber objectVN = vnFrame.getStackValue(lhsPos);
ValueNumber argVN = vnFrame.getStackValue(stackPos);
if (objectVN.equals(argVN)) {
String bugPattern = "DMI_COLLECTIONS_SHOULD_NOT_CONTAIN_THEMSELVES";
int priority = HIGH_PRIORITY;
if (invokedMethodName.equals("removeAll")) {
bugPattern = "DMI_USING_REMOVEALL_TO_CLEAR_COLLECTION";
priority = NORMAL_PRIORITY;
} else if (invokedMethodName.endsWith("All")) {
bugPattern = "DMI_VACUOUS_SELF_COLLECTION_CALL";
priority = NORMAL_PRIORITY;
}
if (invokedMethodName.startsWith("contains")) {
InstructionHandle next = handle.getNext();
if (next != null) {
Instruction nextIns = next.getInstruction();
if (nextIns instanceof InvokeInstruction) {
XMethod nextMethod = XFactory.createXMethod((InvokeInstruction) nextIns, cpg);
if (nextMethod.getName().equals("assertFalse")) continue;
}
}
}
accumulator.accumulateBug(
new BugInstance(this, bugPattern, priority)
.addClassAndMethod(methodGen, sourceFile)
.addCalledMethod(methodGen, (InvokeInstruction) ins)
.addOptionalAnnotation(
ValueNumberSourceInfo.findAnnotationFromValueNumber(
method, location, objectVN, vnFrame, "INVOKED_ON")),
SourceLineAnnotation.fromVisitedInstruction(
classContext, methodGen, sourceFile, handle));
}
// Only consider generic...
Type objectType = frame.getStackValue(lhsPos);
if (!(objectType instanceof GenericObjectType)) continue;
GenericObjectType operand = (GenericObjectType) objectType;
int expectedTypeParameters = 1;
String simpleName = info.interfaceForCall.getSimpleName();
if (simpleName.toLowerCase().endsWith("map") || simpleName.equals("Hashtable"))
expectedTypeParameters = 2;
else if (simpleName.equals("Table")) expectedTypeParameters = 3;
// ... containers
if (!operand.hasParameters()) continue;
if (operand.getNumParameters() != expectedTypeParameters) continue;
ClassDescriptor operandClass = DescriptorFactory.getClassDescriptor(operand);
if (!isGenericCollection(operandClass)) continue;
if (expectedTypeParameters == 2
&& Subtypes2.instanceOf(operandClass, Map.class)
&& !TypeFrameModelingVisitor.isStraightGenericMap(operandClass)) continue;
Type expectedType;
if (allMethod) expectedType = operand;
else expectedType = operand.getParameterAt(typeArgument);
Type actualType = frame.getStackValue(stackPos);
Type equalsType = actualType;
if (allMethod) {
if (!(actualType instanceof GenericObjectType)) {
continue;
}
equalsType = ((GenericObjectType) actualType).getParameterAt(typeArgument);
}
IncompatibleTypes matchResult = compareTypes(expectedType, actualType, allMethod);
boolean parmIsObject = expectedType.getSignature().equals("Ljava/lang/Object;");
boolean selfOperation = !allMethod && operand.equals(actualType) && !parmIsObject;
if (!allMethod && !parmIsObject && actualType instanceof GenericObjectType) {
GenericObjectType p2 = (GenericObjectType) actualType;
List<? extends ReferenceType> parameters = p2.getParameters();
if (parameters != null && parameters.equals(operand.getParameters()))
selfOperation = true;
}
if (!selfOperation
&& (matchResult == IncompatibleTypes.SEEMS_OK
|| matchResult.getPriority() == Priorities.IGNORE_PRIORITY)) continue;
if (invokedMethodName.startsWith("contains") || invokedMethodName.equals("remove")) {
InstructionHandle next = handle.getNext();
if (next != null) {
Instruction nextIns = next.getInstruction();
if (nextIns instanceof InvokeInstruction) {
XMethod nextMethod = XFactory.createXMethod((InvokeInstruction) nextIns, cpg);
if (nextMethod.getName().equals("assertFalse")) continue;
}
}
} else if (invokedMethodName.equals("get") || invokedMethodName.equals("remove")) {
InstructionHandle next = handle.getNext();
if (next != null) {
Instruction nextIns = next.getInstruction();
if (nextIns instanceof InvokeInstruction) {
XMethod nextMethod = XFactory.createXMethod((InvokeInstruction) nextIns, cpg);
if (nextMethod.getName().equals("assertNull")) continue;
}
}
}
boolean noisy = false;
if (invokedMethodName.equals("get")) {
UnconditionalValueDerefDataflow unconditionalValueDerefDataflow =
classContext.getUnconditionalValueDerefDataflow(method);
UnconditionalValueDerefSet unconditionalDeref =
unconditionalValueDerefDataflow.getFactAtLocation(location);
ValueNumberFrame vnAfter = vnDataflow.getFactAfterLocation(location);
ValueNumber top = vnAfter.getTopValue();
noisy =
unconditionalDeref.getValueNumbersThatAreUnconditionallyDereferenced().contains(top);
}
// Prepare bug report
SourceLineAnnotation sourceLineAnnotation =
SourceLineAnnotation.fromVisitedInstruction(
classContext, methodGen, sourceFile, handle);
// Report a bug that mentions each of the failed arguments in
// matches
if (expectedType instanceof GenericObjectType)
expectedType = ((GenericObjectType) expectedType).getUpperBound();
int priority = matchResult.getPriority();
if (!operandClass.getClassName().startsWith("java/util")
&& priority == Priorities.HIGH_PRIORITY)
priority = Math.max(priority, Priorities.NORMAL_PRIORITY);
if (TestCaseDetector.likelyTestCase(xmethod))
priority = Math.max(priority, Priorities.NORMAL_PRIORITY);
else if (selfOperation) priority = Priorities.HIGH_PRIORITY;
ClassDescriptor expectedClassDescriptor =
DescriptorFactory.createClassOrObjectDescriptorFromSignature(
expectedType.getSignature());
ClassDescriptor actualClassDescriptor =
DescriptorFactory.createClassOrObjectDescriptorFromSignature(equalsType.getSignature());
ClassSummary classSummary = AnalysisContext.currentAnalysisContext().getClassSummary();
Set<XMethod> targets = null;
try {
targets =
Hierarchy2.resolveVirtualMethodCallTargets(
actualClassDescriptor, "equals", "(Ljava/lang/Object;)Z", false, false);
boolean allOk = targets.size() > 0;
for (XMethod m2 : targets)
if (!classSummary.mightBeEqualTo(m2.getClassDescriptor(), expectedClassDescriptor))
allOk = false;
if (allOk) priority += 2;
} catch (ClassNotFoundException e) {
AnalysisContext.reportMissingClass(e);
}
String bugPattern = "GC_UNRELATED_TYPES";
BugInstance bug =
new BugInstance(this, bugPattern, priority)
.addClassAndMethod(methodGen, sourceFile)
.addFoundAndExpectedType(actualType, expectedType)
.addCalledMethod(methodGen, (InvokeInstruction) ins)
.addOptionalAnnotation(
ValueNumberSourceInfo.findAnnotationFromValueNumber(
method, location, objectVN, vnFrame, "INVOKED_ON"))
.addOptionalAnnotation(
ValueNumberSourceInfo.findAnnotationFromValueNumber(
method, location, argVN, vnFrame, "ARGUMENT"))
.addEqualsMethodUsed(targets);
if (noisy) {
WarningPropertySet<WarningProperty> propertySet =
new WarningPropertySet<WarningProperty>();
propertySet.addProperty(GeneralWarningProperty.NOISY_BUG);
propertySet.decorateBugInstance(bug);
}
accumulator.accumulateBug(bug, sourceLineAnnotation);
}
}
accumulator.reportAccumulatedBugs();
}