Neo Tokyo contest - arialblack14's results

GAS OPTIMIZATION REPORT

Summary of optimizations

Total: 5 issues.

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Gas Optimizations

<a id=G1>[G-1]</a> Usage of uints/ints smaller than 32 bytes (256 bits) incurs overhead.

Description

When using elements that are smaller than 32 bytes, your contract’s gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller than that, the EVM must use more operations in order to reduce the size of the element from 32 bytes to the desired size.

Recommendation

Use uint256 instead.

Instances (7):

File: 2023-03-neotokyo/contracts/staking/NeoTokyoStaker.sol

291: uint128 startTime;
292: uint128 reward;
963: uint256 timelockMultiplier = _timelock & type(uint128).max;
1017: uint256 timelockMultiplier = _timelock & type(uint128).max;
1141: uint256 timelockMultiplier = _timelock & type(uint128).max;
1205: if (uint8(_assetType) > 4) {
1668: if (uint8(_assetType) == 2 || uint8(_assetType) > 4) {

<a id=G2>[G-2]</a> Multiple accesses of a mapping/array should use a local variable cache.

Description

The instances below point to the second+ access of a value inside a mapping/array, within a function. Caching a mapping's value in a local storage or calldata variable when the value is accessed multiple times, saves ~42 gas per access due to not having to recalculate the key's keccak256 hash (Gkeccak256 - 30 gas) and that calculation's associated stack operations. Caching an array's struct avoids recalculating the array offsets into memory/calldata. Similar findings

Recommendation

Use a local variable cache.

Instances (7):

File: 2023-03-neotokyo/contracts/staking/NeoTokyoStaker.sol

1823: uint256 poolRewardWindowCount = _inputs[i].rewardWindows.length;
1824: _pools[_inputs[i].assetType].rewardCount = poolRewardWindowCount;
1825: _pools[_inputs[i].assetType].daoTax = _inputs[i].daoTax;
1830: _pools[_inputs[i].assetType].rewardWindows[j] =
1831: _inputs[i].rewardWindows[j];
1834: if (j != 0 && _inputs[i].rewardWindows[j].startTime <= lastTime) {
1837: lastTime = _inputs[i].rewardWindows[j].startTime;

<a id=G3>[G-3]</a> >= costs less gas than >.

Description

The compiler uses opcodes GT and ISZERO for solidity code that uses >, but only requires LT for >=, which saves 3 gas

Recommendation

Use >= instead if appropriate.

Instances (8):

File: 2023-03-neotokyo/contracts/staking/BYTES2.sol

123: if (reward > 0) {
126: if (daoCommision > 0) {

File: 2023-03-neotokyo/contracts/staking/NeoTokyoStaker.sol

1066: if (citizenStatus.stakedBytes + amount > cap) {
1087: if (citizenStatus.stakedBytes + amount > cap) {
1205: if (uint8(_assetType) > 4) {
1477: if (stakedCitizen.stakedBytes > 0) {
1552: if (stakedCitizen.stakedBytes > 0) {
1668: if (uint8(_assetType) == 2 || uint8(_assetType) > 4) {

<a id=G4>[G-4]</a> <x> += <y> costs more gas than <x> = <x> + <y> for state variables

Description

Using the addition operator instead of plus-equals saves 113 gas

Recommendation

Use <x> = <x> + <y> or <x> = <x> -<y> instead.

Instances (22):

File: 2023-03-neotokyo/contracts/staking/NeoTokyoStaker.sol

977: pool.totalPoints += citizenStatus.points;
1029: pool.totalPoints += citizenStatus.points;
1078: citizenStatus.stakedBytes += amount;
1079: citizenStatus.points += bonusPoints;
1080: pool.totalPoints += bonusPoints;
1099: citizenStatus.stakedBytes += amount;
1100: citizenStatus.points += bonusPoints;
1101: pool.totalPoints += bonusPoints;
1160: stakerLPPosition[msg.sender].amount += amount;
1161: stakerLPPosition[msg.sender].points += points;
1164: pool.totalPoints += points;
1283: points += s1Citizen.points;
1292: points += s2Citizen.points;
1298: points += stakerLPPosition[_recipient].points;
1332: totalReward += currentRewardRate * timeSinceReward;
1343: totalReward += currentRewardRate * timeSinceReward;
1357: totalReward += currentRewardRate * timeSinceReward;
1515: pool.totalPoints -= stakedCitizen.points;
1580: pool.totalPoints -= stakedCitizen.points;
1626: lpPosition.amount -= amount;
1627: lpPosition.points -= points;
1630: pool.totalPoints -= points;

<a id=G5>[G-5]</a> Using fixed bytes is cheaper than using string.

Description

As a rule of thumb, use bytes for arbitrary-length raw byte data and string for arbitrary-length string (UTF-8) data. If you can limit the length to a certain number of bytes, always use one of bytes1 to bytes32 because they are much cheaper..

Recommendation

Use fixed bytes instead of string.

Instances (7):

File: 2023-03-neotokyo/contracts/staking/NeoTokyoStaker.sol

628: ) public view returns (string memory) {
639: string memory vaultMultiplier = (_vaultId != 0)
665: string memory vaultMultiplier = (_vaultId != 0)
825: string memory _a,
826: string memory _b
939: string memory citizenCreditYield = getCreditYield(
949: string memory class = IGenericGetter(IDENTITY).getClass(identityId);