private Collection<Edge> getRelevantChildrenOfState(
ARGState currentElement, Stack<FunctionBody> functionStack, Set<ARGState> elementsOnPath) {
// find the next elements to add to the waitlist
List<ARGState> relevantChildrenOfElement =
from(currentElement.getChildren()).filter(in(elementsOnPath)).toList();
relevantChildrenOfElement = chooseIfArbitrary(currentElement, relevantChildrenOfElement);
// if there is only one child on the path
if (relevantChildrenOfElement.size() == 1) {
// get the next ARG state, create a new edge using the same stack and add it to the waitlist
ARGState elem = Iterables.getOnlyElement(relevantChildrenOfElement);
CFAEdge e = currentElement.getEdgeToChild(elem);
Edge newEdge = new Edge(elem, currentElement, e, functionStack);
return Collections.singleton(newEdge);
} else if (relevantChildrenOfElement.size() > 1) {
// if there are more than one relevant child, then this is a condition
// we need to update the stack
assert relevantChildrenOfElement.size() == 2;
Collection<Edge> result = new ArrayList<>(2);
int ind = 0;
for (ARGState elem : relevantChildrenOfElement) {
Stack<FunctionBody> newStack = cloneStack(functionStack);
CFAEdge e = currentElement.getEdgeToChild(elem);
FunctionBody currentFunction = newStack.peek();
assert e instanceof CAssumeEdge;
CAssumeEdge assumeEdge = (CAssumeEdge) e;
boolean truthAssumption = assumeEdge.getTruthAssumption();
String cond = "";
if (ind == 0) {
cond = "if ";
} else if (ind == 1) {
cond = "else if ";
} else {
throw new AssertionError();
}
ind++;
if (truthAssumption) {
cond += "(" + assumeEdge.getExpression().toASTString() + ")";
} else {
cond += "(!(" + assumeEdge.getExpression().toASTString() + "))";
}
// create a new block starting with this condition
currentFunction.enterBlock(currentElement.getStateId(), assumeEdge, cond);
Edge newEdge = new Edge(elem, currentElement, e, newStack);
result.add(newEdge);
}
return result;
}
return Collections.emptyList();
}
@Override
public ARGPath getNextPathForInterpolation() {
ARGState current = sources.remove(0);
assert current.isTarget() : "current element is not a target";
ARGPathBuilder errorPathBuilder = ARGPath.reverseBuilder();
errorPathBuilder.add(
current, FluentIterable.from(AbstractStates.getOutgoingEdges(current)).first().orNull());
while (predecessorRelation.get(current) != null) {
ARGState parent = predecessorRelation.get(current);
if (stateHasFalseInterpolant(parent)) {
logger.log(
Level.FINEST,
"interpolant on path, namely for state ",
parent.getStateId(),
" is already false, so return empty path");
return EMPTY_PATH;
}
if (predecessorRelation.get(parent) != null) {
errorPathBuilder.add(parent, parent.getEdgeToChild(current));
}
current = parent;
}
return errorPathBuilder.build(current);
}
@Override
public ARGPath getNextPathForInterpolation() {
ARGPathBuilder errorPathBuilder = ARGPath.builder();
ARGState current = sources.pop();
if (!isValidInterpolationRoot(predecessorRelation.get(current))) {
logger.log(
Level.FINEST,
"interpolant of predecessor of ",
current.getStateId(),
" is already false, so return empty path");
return EMPTY_PATH;
}
// if the current state is not the root, it is a child of a branch , however, the path should
// not start with the
// child, but with the branching node (children are stored on the stack because this needs
// less book-keeping)
if (current != root) {
errorPathBuilder.add(
predecessorRelation.get(current),
predecessorRelation.get(current).getEdgeToChild(current));
}
while (successorRelation.get(current).iterator().hasNext()) {
Iterator<ARGState> children = successorRelation.get(current).iterator();
ARGState child = children.next();
errorPathBuilder.add(current, current.getEdgeToChild(child));
// push all other children of the current state, if any, onto the stack for later
// interpolations
int size = 1;
while (children.hasNext()) {
size++;
ARGState sibling = children.next();
logger.log(
Level.FINEST,
"\tpush new root ",
sibling.getStateId(),
" onto stack for parent ",
predecessorRelation.get(sibling).getStateId());
sources.push(sibling);
}
assert (size <= 2);
current = child;
}
return errorPathBuilder.build(current);
}
@Override
public boolean apply(ARGState pChild) {
return pChild != null && predecessor.getEdgeToChild(pChild) == edge;
}
private List<BooleanFormula> computeBlockFormulas(final ARGState pRoot)
throws CPATransferException, InterruptedException {
final Map<ARGState, ARGState> callStacks =
new HashMap<>(); // contains states and their next higher callstate
final Map<ARGState, PathFormula> finishedFormulas = new HashMap<>();
final List<BooleanFormula> abstractionFormulas = new ArrayList<>();
final Deque<ARGState> waitlist = new ArrayDeque<>();
// initialize
assert pRoot.getParents().isEmpty() : "rootState must be the first state of the program";
callStacks.put(pRoot, null); // main-start has no callstack
finishedFormulas.put(pRoot, pfmgr.makeEmptyPathFormula());
waitlist.addAll(pRoot.getChildren());
// iterate over all elements in the ARG with BFS
while (!waitlist.isEmpty()) {
final ARGState currentState = waitlist.pollFirst();
if (finishedFormulas.containsKey(currentState)) {
continue; // already handled
}
if (!finishedFormulas.keySet().containsAll(currentState.getParents())) {
// parent not handled yet, re-queue current element and wait for all parents
waitlist.addLast(currentState);
continue;
}
// collect formulas for current location
final List<PathFormula> currentFormulas = new ArrayList<>(currentState.getParents().size());
final List<ARGState> currentStacks = new ArrayList<>(currentState.getParents().size());
for (ARGState parentElement : currentState.getParents()) {
PathFormula parentFormula = finishedFormulas.get(parentElement);
final CFAEdge edge = parentElement.getEdgeToChild(currentState);
assert edge != null : "ARG is invalid: parent has no edge to child";
final ARGState prevCallState;
// we enter a function, so lets add the previous state to the stack
if (edge.getEdgeType() == CFAEdgeType.FunctionCallEdge) {
prevCallState = parentElement;
} else if (edge.getEdgeType() == CFAEdgeType.FunctionReturnEdge) {
// we leave a function, so rebuild return-state before assigning the return-value.
// rebuild states with info from previous state
assert callStacks.containsKey(parentElement);
final ARGState callState = callStacks.get(parentElement);
assert extractLocation(callState).getLeavingSummaryEdge().getSuccessor()
== extractLocation(currentState)
: "callstack does not match entry of current function-exit.";
assert callState != null || currentState.getChildren().isEmpty()
: "returning from empty callstack is only possible at program-exit";
prevCallState = callStacks.get(callState);
parentFormula =
rebuildStateAfterFunctionCall(
parentFormula,
finishedFormulas.get(callState),
(FunctionExitNode) extractLocation(parentElement));
} else {
assert callStacks.containsKey(parentElement); // check for null is not enough
prevCallState = callStacks.get(parentElement);
}
final PathFormula currentFormula = pfmgr.makeAnd(parentFormula, edge);
currentFormulas.add(currentFormula);
currentStacks.add(prevCallState);
}
assert currentFormulas.size() >= 1 : "each state except root must have parents";
assert currentStacks.size() == currentFormulas.size()
: "number of callstacks must match predecessors";
// merging after functioncall with different callstates is ugly.
// this is also guaranteed by the abstraction-locations at function-entries
// (--> no merge of states with different latest abstractions).
assert Sets.newHashSet(currentStacks).size() <= 1
: "function with multiple entry-states not supported";
callStacks.put(currentState, currentStacks.get(0));
PathFormula currentFormula;
final PredicateAbstractState predicateElement =
extractStateByType(currentState, PredicateAbstractState.class);
if (predicateElement.isAbstractionState()) {
// abstraction element is the start of a new part of the ARG
assert waitlist.isEmpty() : "todo should be empty, because of the special ARG structure";
assert currentState.getParents().size() == 1
: "there should be only one parent, because of the special ARG structure";
// finishedFormulas.clear(); // free some memory
// TODO disabled, we need to keep callStates for later usage
// start new block with empty formula
currentFormula = getOnlyElement(currentFormulas);
abstractionFormulas.add(currentFormula.getFormula());
currentFormula = pfmgr.makeEmptyPathFormula(currentFormula);
} else {
// merge the formulas
Iterator<PathFormula> it = currentFormulas.iterator();
currentFormula = it.next();
while (it.hasNext()) {
currentFormula = pfmgr.makeOr(currentFormula, it.next());
}
}
assert !finishedFormulas.containsKey(currentState) : "a state should only be finished once";
finishedFormulas.put(currentState, currentFormula);
waitlist.addAll(currentState.getChildren());
}
return abstractionFormulas;
}