Ex2. Dynamic BasicBlock Count

count-bb.cpp

bool CountBasicBlocks::runOnBasicBlock(BasicBlock &BB, Module &M) {
    // Get the bbCounter GlobalVariable
    GlobalVariable *bbCounter = M.getGlobalVariable("bbCounter");
    assert(bbCounter && "Error: unable to get BasicBlock counter");

    // Insert instructions at the end of this BasicBlock
    TerminatorInst *InsertPos = BB.getTerminator(); 

    // Load, increment and store the value back
    Value *OldVal = new LoadInst(bbCounter, "old.bb.count", InsertPos);
    Value *NewVal = BinaryOperator::Create(
              Instruction::Add
            , OldVal
            , ConstantInt::get(Type::getInt64Ty(BB.getContext()), 1)
            , "new.bb.count"
            , InsertPos);
    new StoreInst(NewVal, bbCounter, InsertPos);

    return true; // IR modified
}