#include "llvm/Pass.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"

using namespace llvm;

namespace {
    struct Hello : public FunctionPass {
        static char ID;
        Hello() : FunctionPass(ID) {}

        bool runOnFunction(Function &F) override;
    };
}

bool Hello::runOnFunction(Function &F) {
    bool changed = false;

    for (auto BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
        for (auto II = BI->begin(), IE = BI->end(); II != IE; ++II) {
            BinaryOperator *BO = dyn_cast<BinaryOperator>(&*II);

            if (!BO)
                continue;

            unsigned opcode = BO->getOpcode();
            errs() << BO->getOpcodeName() << "\n";

            if (opcode != Instruction::Add) {
                continue;
            }

            changed = true;

            IRBuilder<> builder(BO);
            Value* V = builder.CreateAdd(builder.CreateXor(BO->getOperand(0), BO->getOperand(1)),
                       builder.CreateMul(ConstantInt::get(BO->getType(), 2),
                       builder.CreateAnd(BO->getOperand(0), BO->getOperand(1))));

            ReplaceInstWithValue(BI->getInstList(), II, V);
        }
    }

    return changed;
}

char Hello::ID = 0;
static RegisterPass<Hello> X("hello", "Count opcodes per functions", false, false);