@Override
public Region apply(PredicateAbstractState e) {
assert e.isAbstractionState();
return e.getAbstractionFormula().asRegion();
}
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;
}
