bool SDFix::fixDestructors2() {
bool replaced = false;
for (GlobalVariable& gv : module->getGlobalList()) {
if (! sd_isVtableName_ref(gv.getName()))
continue;
else if (! gv.hasInitializer())
continue;
Constant* init = gv.getInitializer();
assert(init);
ConstantArray* vtable = dyn_cast<ConstantArray>(init);
assert(vtable);
for(unsigned i=0; i<vtable->getNumOperands(); i++) {
Constant* destructor = sd_getDestructorFunction(vtable->getOperand(i));
if (destructor == NULL)
continue;
// get the type from its name
unsigned s = destructor->getName().size();
char type = destructor->getName()[s-3];
assert('0' <= type && type <= '2');
unsigned typeInt = type - '0';
DestructorInfo di(destructor, i);
if(di.isDefined)
continue;
// this only handles the 1 -> 2 conversion
assert(typeInt == 1);
Function* f1 = di.getFunction();
assert(f1);
std::string gv2Name = f1->getName();
unsigned l = gv2Name.length();
gv2Name = gv2Name.replace(l-3, 1, "2");
Function* f2 = module->getFunction(gv2Name);
assert(f2 && ! f2->isDeclaration());
sd_print("Replacing %s with %s inside %s\n",
f1->getName().data(),
gv2Name.c_str(),
gv.getName().data());
f1->replaceAllUsesWith(f2);
replaced = true;
}
}
return replaced;
}
static Constant*
sd_getDestructorFunction(Constant* vtblElement) {
ConstantExpr* bcExpr = NULL;
// if this a constant bitcast expression, this might be a vthunk
if ((bcExpr = dyn_cast<ConstantExpr>(vtblElement)) && bcExpr->getOpcode() == BITCAST_OPCODE) {
Constant* operand = bcExpr->getOperand(0);
// this is a vthunk
if (sd_isDestructorName(operand->getName())) {
return operand;
}
}
return NULL;
}
static Constant*
sd_isRTTI(Constant* vtblElement) {
ConstantExpr* bcExpr = NULL;
// if this a constant bitcast expression, this might be a vthunk
if ((bcExpr = dyn_cast<ConstantExpr>(vtblElement)) &&
bcExpr->getOpcode() == Instruction::BitCast) {
Constant* operand = bcExpr->getOperand(0);
// this is a vthunk
if (operand->getName().startswith("_ZTI")) {
return operand;
}
}
return NULL;
}
bool SDFix::fixDestructors() {
bool replaced = false;
for (GlobalVariable& gv : module->getGlobalList()) {
if (! sd_isVtableName_ref(gv.getName()))
continue;
else if (! gv.hasInitializer())
continue;
Constant* init = gv.getInitializer();
assert(init);
ConstantArray* vtable = dyn_cast<ConstantArray>(init);
assert(vtable);
// get an idea about the virtual function regions
std::vector<vtbl_pair_t> vtblRegions = findSubVtables(vtable);
// for each subvtable
for(unsigned vtblInd = 0; vtblInd < vtblRegions.size(); vtblInd++) {
// record the destructors used in the vtable
std::vector<DestructorInfo> destructors(3);
vtbl_pair_t p = vtblRegions[vtblInd];
for(unsigned i=p.first; i<p.second; i++) {
Constant* destructor = sd_getDestructorFunction(vtable->getOperand(i));
if (destructor == NULL)
continue;
// get the type from its name
unsigned s = destructor->getName().size();
char type = destructor->getName()[s-3];
assert('0' <= type && type <= '2');
unsigned typeInt = type - '0';
// store it temporarily
destructors[typeInt] = DestructorInfo(destructor, i);
}
// deleting destructor should always be defined
assert(! destructors[0].needsReplacement());
DestructorInfo* d1 = &destructors[1];
DestructorInfo* d2 = &destructors[2];
// only one of the rest could be undefined
assert(! d1->needsReplacement() || ! d2->needsReplacement());
// if complete object destructor is missing...
if (d1->needsReplacement()) {
std::string gv2Name = d1->function->getName();
unsigned l = gv2Name.length();
gv2Name = gv2Name.replace(l-3, 1, "2");
Function* f1 = d1->getFunction();
assert(f1);
Function* f2 = module->getFunction(gv2Name);
assert(f2);
sd_print("Replacing %s with %s inside %s\n",
d1->function->getName().data(),
gv2Name.c_str(),
gv.getName().data());
f1->replaceAllUsesWith(f2);
replaced = true;
// if base object destructor is missing...
} else if (d2->needsReplacement()) {
std::string gv1Name = d2->function->getName();
unsigned l = gv1Name.length();
gv1Name = gv1Name.replace(l-3, 1, "1");
Function* f2 = d2->getFunction();
assert(f2);
Function* f1 = module->getFunction(gv1Name);
assert(f1);
sd_print("Replacing %s with %s inside %s\n",
d2->function->getName().data(),
gv1Name.c_str(),
gv.getName().data());
f2->replaceAllUsesWith(f1);
replaced = true;
}
}
}
return replaced;
}
