void PerfMonitor::addToGlobalConstructors(Function *Fn) {
const char *Name = "llvm.global_ctors";
GlobalVariable *GV = M->getGlobalVariable(Name);
std::vector<Constant *> V;
if (GV) {
Constant *Array = GV->getInitializer();
for (Value *X : Array->operand_values())
V.push_back(cast<Constant>(X));
GV->eraseFromParent();
}
StructType *ST = StructType::get(Builder.getInt32Ty(), Fn->getType(),
Builder.getInt8PtrTy());
V.push_back(
ConstantStruct::get(ST, Builder.getInt32(10), Fn,
ConstantPointerNull::get(Builder.getInt8PtrTy())));
ArrayType *Ty = ArrayType::get(ST, V.size());
GV = new GlobalVariable(*M, Ty, true, GlobalValue::AppendingLinkage,
ConstantArray::get(Ty, V), Name, nullptr,
GlobalVariable::NotThreadLocal);
}
