/**
* builds a formula that represents the necessary variable assignments to "merge" the two ssa
* maps. That is, for every variable X that has two different ssa indices i and j in the maps,
* creates a new formula (X_k = X_i) | (X_k = X_j), where k is a fresh ssa index. Returns the
* formula described above, plus a new SSAMap that is the merge of the two.
*
* @param ssa1 an SSAMap
* @param pts1 the PointerTargetSet for ssa1
* @param ssa2 an SSAMap
* @param pts2 the PointerTargetSet for ssa1
* @return The new SSAMap and the formulas that need to be added to the path formulas before
* disjuncting them.
*/
MergeResult<SSAMap> mergeSSAMaps(
final SSAMap ssa1,
final PointerTargetSet pts1,
final SSAMap ssa2,
final PointerTargetSet pts2)
throws InterruptedException {
final List<MapsDifference.Entry<String, Integer>> symbolDifferences = new ArrayList<>();
final SSAMap resultSSA = SSAMap.merge(ssa1, ssa2, collectMapsDifferenceTo(symbolDifferences));
BooleanFormula mergeFormula1 = bfmgr.makeTrue();
BooleanFormula mergeFormula2 = bfmgr.makeTrue();
for (final MapsDifference.Entry<String, Integer> symbolDifference : symbolDifferences) {
shutdownNotifier.shutdownIfNecessary();
final String symbolName = symbolDifference.getKey();
final CType symbolType = resultSSA.getType(symbolName);
final int index1 = symbolDifference.getLeftValue().orElse(1);
final int index2 = symbolDifference.getRightValue().orElse(1);
assert symbolName != null;
if (index1 > index2 && index1 > 1) {
// i2:smaller, i1:bigger
// => need correction term for i2
BooleanFormula mergeFormula = makeSsaMerger(symbolName, symbolType, index2, index1, pts2);
mergeFormula2 = bfmgr.and(mergeFormula2, mergeFormula);
} else if (index2 > 1) {
assert index1 < index2;
// i1:smaller, i2:bigger
// => need correction term for i1
BooleanFormula mergeFormula = makeSsaMerger(symbolName, symbolType, index1, index2, pts1);
mergeFormula1 = bfmgr.and(mergeFormula1, mergeFormula);
}
}
return new MergeResult<>(resultSSA, mergeFormula1, mergeFormula2, bfmgr.makeTrue());
}
BooleanFormula addMergeAssumptions(
final BooleanFormula pFormula,
final SSAMap ssa1,
final PointerTargetSet pts1,
final SSAMap ssa2)
throws InterruptedException {
final List<MapsDifference.Entry<String, Integer>> symbolDifferences = new ArrayList<>();
final SSAMap resultSSA = SSAMap.merge(ssa1, ssa2, collectMapsDifferenceTo(symbolDifferences));
List<BooleanFormula> mergeFormula = new ArrayList<>();
mergeFormula.add(pFormula);
for (final MapsDifference.Entry<String, Integer> symbolDifference : symbolDifferences) {
shutdownNotifier.shutdownIfNecessary();
final String symbolName = symbolDifference.getKey();
final CType symbolType = resultSSA.getType(symbolName);
final int index1 = symbolDifference.getLeftValue().orElse(1);
final int index2 = symbolDifference.getRightValue().orElse(1);
assert symbolName != null;
if (index1 > index2 && index1 > 1) {
// assumption violated
// ssa2 is not the merge result of ssa1 and further ssa maps
// simplify following PCC coverage check which will likely fail anyway
// and return coarsest overapproximation
return bfmgr.makeTrue();
} else if (index2 > 1) {
assert index1 < index2;
// i1:smaller, i2:bigger
// => need correction term for i1
for (int i = index1; i < index2; i++) {
mergeFormula.add(makeSsaMerger(symbolName, symbolType, i, i + 1, pts1));
}
}
}
return bfmgr.and(mergeFormula);
}