Neo Tokyo contest - pipoca's results

1. Using x += y or x -= y instead of x = x + y or x = x - y can be less gas-efficient

File: NeoTokyoStaker.sol | Line: 977 | pool.totalPoints += citizenStatus.points; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L977 File: NeoTokyoStaker.sol | Line: 1078 | citizenStatus.stakedBytes += amount; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1078 File: NeoTokyoStaker.sol | Line: 1079 | citizenStatus.points += bonusPoints; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1079 File: NeoTokyoStaker.sol | Line: 1080 | pool.totalPoints += bonusPoints; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1080 File: NeoTokyoStaker.sol | Line: 1160 | stakerLPPosition[msg.sender].amount += amount; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1160 File: NeoTokyoStaker.sol | Line: 1161 | stakerLPPosition[msg.sender].points += points; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1161 File: NeoTokyoStaker.sol | Line: 1164 | pool.totalPoints += points; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1164 File: NeoTokyoStaker.sol | Line: 1283 | points += s1Citizen.points; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1283 File: NeoTokyoStaker.sol | Line: 1292 | points += s2Citizen.points; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1292 File: NeoTokyoStaker.sol | Line: 1298 | points += stakerLPPosition[_recipient].points; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1298 File: NeoTokyoStaker.sol | Line: 1332 | totalReward += currentRewardRate * timeSinceReward; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1332 File: NeoTokyoStaker.sol | Line: 1343 | totalReward += currentRewardRate * timeSinceReward; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1343 File: NeoTokyoStaker.sol | Line: 1357 | totalReward += currentRewardRate * timeSinceReward; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1357 File: NeoTokyoStaker.sol | Line: 1515 | pool.totalPoints -= stakedCitizen.points; https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1515

2. ++i is more gas efficient than i++

This is because the pre-increment operator directly modifies the variable's value, while the post-increment operator requires an additional read and write operation to modify the value.

https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L728

https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L743

https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1284

https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1293

https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1383

3. Caching Array Length in For Loops for Gas Savings

By storing the length of the array in a local variable before the loop, the loop header can reference this variable instead of accessing the length of the array multiple times

File: NeoTokyoStaker.sol | Line: 734 | for (uint256 i; i < _stakerS2Position[_staker].length; ) { https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L734

File: NeoTokyoStaker.sol | Line: 1279 | for (uint256 i; i < _stakerS1Position[_recipient].length; ) { https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1279

File: NeoTokyoStaker.sol | Line: 1288 | for (uint256 i; i < _stakerS2Position[_recipient].length; ) { https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1288

File: NeoTokyoStaker.sol | Line: 1499 | for (uint256 stakedIndex; stakedIndex < oldPosition.length; ) { https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L1499

4. Use bytes(x) instead of string where possible to save gas

File: NeoTokyoStaker.sol | Line: 639 | string memory vaultMultiplier = (_vaultId != 0) https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L639 File: NeoTokyoStaker.sol | Line: 665 | string memory vaultMultiplier = (_vaultId != 0) https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L665 File: NeoTokyoStaker.sol | Line: 639 | string memory vaultMultiplier = (_vaultId != 0) https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L639 File: NeoTokyoStaker.sol | Line: 665 | string memory vaultMultiplier = (_vaultId != 0) https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L665 File: NeoTokyoStaker.sol | Line: 939 | string memory citizenCreditYield = getCreditYield( https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L939 File: NeoTokyoStaker.sol | Line: 949 | string memory class = IGenericGetter(IDENTITY).getClass(identityId); https://github.com/code-423n4/2023-03-neotokyo/blob/main/contracts/staking/NeoTokyoStaker.sol#L949

5. Caching External Contract Calls

In the upgradeBytes function, there are two external contract calls:

IERC20(BYTES1).balanceOf(msg.sender) IByteContract(BYTES1).burn(msg.sender, _amount)

These calls can be optimized by storing the contract instance in a variable and reusing it, rather than creating a new instance for each call. This will save gas by reducing the overhead associated with creating new instances.

`function upgradeBytes(uint256 _amount) external IERC20 bytes1Contract = IERC20(BYTES1);

if (bytes1Contract.balanceOf(msg.sender) < _amount) {
    revert DoNotHaveEnoughOldBytes(_amount);
}

IByteContract(address(bytes1Contract)).burn(msg.sender, _amount);
_mint(msg.sender, _amount);

emit BytesUpgraded(msg.sender, _amount);

}