private void computeOutgoingEdges() {
if (DEBUG) {
System.err.println("Block " + this + ": computeOutgoingEdges()");
}
IInstruction last = getInstructions()[getLastInstructionIndex()];
int[] targets = last.getBranchTargets();
for (int i = 0; i < targets.length; i++) {
BasicBlock b = getBlockForInstruction(targets[i]);
addNormalEdgeTo(b);
}
addExceptionalEdges(last);
if (last.isFallThrough()) {
BasicBlock next = getNode(getNumber() + 1);
addNormalEdgeTo(next);
}
if (last instanceof ReturnInstruction) {
// link each return instruction to the exit block.
BasicBlock exit = exit();
addNormalEdgeTo(exit);
}
}
/**
* Add any exceptional edges generated by the last instruction in a basic block.
*
* @param last the last instruction in a basic block.
*/
protected void addExceptionalEdges(IInstruction last) {
IClassHierarchy cha = getMethod().getClassHierarchy();
if (last.isPEI()) {
Collection<TypeReference> exceptionTypes = null;
boolean goToAllHandlers = false;
ExceptionHandler[] hs = getExceptionHandlers();
if (last instanceof ThrowInstruction) {
// this class does not have the type information needed
// to determine what the athrow throws. So, add an
// edge to all reachable handlers. Better information can
// be obtained later with SSA type propagation.
// TODO: consider pruning to only the exception types that
// this method either catches or allocates, since these are
// the only types that can flow to an athrow.
goToAllHandlers = true;
} else {
if (hs != null && hs.length > 0) {
IClassLoader loader = getMethod().getDeclaringClass().getClassLoader();
BytecodeLanguage l = (BytecodeLanguage) loader.getLanguage();
exceptionTypes = l.getImplicitExceptionTypes(last);
if (last instanceof IInvokeInstruction) {
IInvokeInstruction call = (IInvokeInstruction) last;
exceptionTypes = HashSetFactory.make(exceptionTypes);
MethodReference target =
MethodReference.findOrCreate(
l,
loader.getReference(),
call.getClassType(),
call.getMethodName(),
call.getMethodSignature());
try {
exceptionTypes.addAll(l.inferInvokeExceptions(target, cha));
} catch (InvalidClassFileException e) {
e.printStackTrace();
Assertions.UNREACHABLE();
}
}
}
}
if (hs != null && hs.length > 0) {
// found a handler for this PEI
// create a mutable copy
if (!goToAllHandlers) {
exceptionTypes = HashSetFactory.make(exceptionTypes);
}
// this var gets set to false if goToAllHandlers is true but some enclosing exception
// handler catches all
// exceptions. in such a case, we need not add an exceptional edge to the method exit
boolean needEdgeToExitForAllHandlers = true;
for (int j = 0; j < hs.length; j++) {
if (DEBUG) {
System.err.println(" handler " + hs[j]);
}
BasicBlock b = getBlockForInstruction(hs[j].getHandler());
if (DEBUG) {
System.err.println(" target " + b);
}
if (goToAllHandlers) {
// add an edge to the catch block.
if (DEBUG) {
System.err.println(" gotoAllHandlers " + b);
}
addExceptionalEdgeTo(b);
// if the handler catches all exceptions, we don't need to add an edge to the exit or
// any other handlers
if (hs[j].getCatchClass() == null) {
needEdgeToExitForAllHandlers = false;
break;
}
} else {
TypeReference caughtException = null;
if (hs[j].getCatchClass() != null) {
ClassLoaderReference loader =
ShrikeCFG.this.getMethod().getDeclaringClass().getReference().getClassLoader();
caughtException = ShrikeUtil.makeTypeReference(loader, hs[j].getCatchClass());
if (DEBUG) {
System.err.println(" caughtException " + caughtException);
}
IClass caughtClass = cha.lookupClass(caughtException);
if (caughtClass == null) {
// conservatively add the edge, and raise a warning
addExceptionalEdgeTo(b);
Warnings.add(FailedExceptionResolutionWarning.create(caughtException));
// null out caughtException, to avoid attempting to process it
caughtException = null;
}
} else {
if (DEBUG) {
System.err.println(" catchClass() == null");
}
// hs[j].getCatchClass() == null.
// this means that the handler catches all exceptions.
// add the edge and null out all types
if (!exceptionTypes.isEmpty()) {
addExceptionalEdgeTo(b);
exceptionTypes.clear();
caughtException = null;
}
}
if (caughtException != null) {
IClass caughtClass = cha.lookupClass(caughtException);
// the set "caught" should be the set of exceptions that MUST
// have been caught by the handlers in scope
ArrayList<TypeReference> caught =
new ArrayList<TypeReference>(exceptionTypes.size());
// check if we should add an edge to the catch block.
for (TypeReference t : exceptionTypes) {
if (t != null) {
IClass klass = cha.lookupClass(t);
if (klass == null) {
Warnings.add(FailedExceptionResolutionWarning.create(caughtException));
// conservatively add an edge
addExceptionalEdgeTo(b);
} else {
boolean subtype1 = cha.isSubclassOf(klass, caughtClass);
if (subtype1 || cha.isSubclassOf(caughtClass, klass)) {
// add the edge and null out the type from the array
addExceptionalEdgeTo(b);
if (subtype1) {
caught.add(t);
}
}
}
}
}
exceptionTypes.removeAll(caught);
}
}
}
// if needed, add an edge to the exit block.
if ((exceptionTypes == null && needEdgeToExitForAllHandlers)
|| (exceptionTypes != null && !exceptionTypes.isEmpty())) {
BasicBlock exit = exit();
addExceptionalEdgeTo(exit);
}
} else {
// found no handler for this PEI ... link to the exit block.
BasicBlock exit = exit();
addExceptionalEdgeTo(exit);
}
}
}