void ClassHierarchyUtils::findClassHierarchy(Module& M) {
// extract call hierarchy using std::type_info structures rather
// than debug info. The former works even for when there are anonymous
// namespaces. type_info structs can be obtained from vtable globals.
// (for more info, see http://mentorembedded.github.io/cxx-abi/abi.html)
for (Module::global_iterator I=M.global_begin(), E=M.global_end(); I != E; I++) {
GlobalVariable* G = &*I;
if (G->getName().startswith("_ZTV")) {
if (G->hasInitializer()) {
SDEBUG("soaap.util.classhierarchy", 3, G->dump());
ConstantArray* Ginit = cast<ConstantArray>(G->getInitializer());
// Ginit[1] is the type_info global for this vtable's type
bool typeInfoFound = false;
bool primaryVTable = true;
for (int i=0; i<Ginit->getNumOperands(); i++) {
// typeinfo will be the first global variable in the array.
// It's not always at a fixed index so we have to search for it...
if (GlobalVariable* TI = dyn_cast<GlobalVariable>(Ginit->getOperand(i)->stripPointerCasts())) {
//TI->dump();
typeInfoToVTable[TI] = G;
vTableToTypeInfo[G] = TI;
processTypeInfo(TI); // process TI recursively (it contains refs to super-class TIs)
typeInfoFound = true;
if (primaryVTable) {
primaryVTable = false;
vTableToSecondaryVTableMaps[G][0] = i+1; // i+1 is also the size of the vtable header
}
else {
// offset_to_top is at the previous index
ConstantExpr* offsetValCast = cast<ConstantExpr>(Ginit->getOperand(i-1)->stripPointerCasts());
ConstantInt* offsetVal = cast<ConstantInt>(offsetValCast->getOperand(0));
int offsetToTop = offsetVal->getSExtValue();
if (offsetToTop > 0) {
dbgs() << "ERROR: offsetToTop is positive!\n";
G->dump();
}
else {
offsetToTop *= -1;
}
SDEBUG("soaap.util.classhierarchy", 3, dbgs() << "offsetToTop: " << offsetToTop << "\n");
vTableToSecondaryVTableMaps[G][offsetToTop] = i+1;
}
}
}
if (!typeInfoFound) {
dbgs() << "ERROR: vtable initializer is not a global variable...\n";
dbgs() << *G << " = " << *Ginit << "\n";
}
}
}
}
SDEBUG("soaap.util.classhierarchy", 3, ppClassHierarchy(classToSubclasses));
}
