Velodrome Finance contest - MadWookie's results

Gas Report

All calculations for gas saved came from

forge test --gas-report 

Gauge.sol

constructor

File: Gauge.sol#110-119

isForPair = _isForPair;
        if (isForPair) {
            (address _token0, address _token1) = IPair(stake).tokens();
            IBribe(bribe).addRewardToken(_token0);
            isReward[_token0] = true;
            rewards.push(_token0);
            IBribe(bribe).addRewardToken(_token1);
            isReward[_token1] = true;
            rewards.push(_token1);
        }

Only set isForpair in the if statement. The default value for bools are false so if _isForPair is false gas is being wasted.

I suggest changing it to the code below, which saves 2,245 gas on deployment.

 if (_isForPair) {
            (address _token0, address _token1) = IPair(stake).tokens();
            IBribe(bribe).addRewardToken(_token0);
            isReward[_token0] = true;
            rewards.push(_token0);
            IBribe(bribe).addRewardToken(_token1);
            isReward[_token1] = true;
            rewards.push(_token1);
            isForPair = _isForPair;
        }

Bribe.sol

function notifyRewardAmount()

File: Bribe.sol#41-60

function notifyRewardAmount(address token, uint amount) external lock {
      require(amount > 0);
      if (!isReward[token]) {
        require(rewards.length < MAX_REWARD_TOKENS, "too many rewards tokens");
      }
      // bribes kick in at the start of next bribe period
      uint adjustedTstamp = getEpochStart(block.timestamp);
      uint epochRewards = tokenRewardsPerEpoch[token][adjustedTstamp];

      _safeTransferFrom(token, msg.sender, address(this), amount);
      tokenRewardsPerEpoch[token][adjustedTstamp] = epochRewards + amount;

      if (!isReward[token]) {
          isReward[token] = true;
          rewards.push(token);
          IGauge(gauge).addBribeRewardToken(token);
      }

      emit NotifyReward(msg.sender, token, adjustedTstamp, amount);
  }

isReward[token] is used twice and can be cached in memory to save gas. The below implementation saves 149 gas per function call and 2,607 on deployment.

function notifyRewardAmount(address token, uint amount) external lock {
      require(amount > 0);
      bool _isReward = isReward[token];

      if (!_isReward) {
        require(rewards.length < MAX_REWARD_TOKENS, "too many rewards tokens");
      }
      // bribes kick in at the start of next bribe period
      uint adjustedTstamp = getEpochStart(block.timestamp);
      uint epochRewards = tokenRewardsPerEpoch[token][adjustedTstamp];

      _safeTransferFrom(token, msg.sender, address(this), amount);
      tokenRewardsPerEpoch[token][adjustedTstamp] = epochRewards + amount;

      if (!_isReward) {
          isReward[token] = true;
          rewards.push(token);
          IGauge(gauge).addBribeRewardToken(token);
      }

      emit NotifyReward(msg.sender, token, adjustedTstamp, amount);
  }

Voter.sol

function _reset()

File: Voter.sol#118

totalWeight -= uint256(_totalWeight);

totalWeight should never underflow here. Changing to the code below saves 74 gas.

unchecked {
        totalWeight -= uint256(_totalWeight);
        }

For-loops

For loops can be made cheaper by using unchecked arithmetic when increasing the incrementor. In my opinion since this code base has a great deal of for-loops it would be a large benefit even if readability is reduced a little. At the very minimum i++ should be changed to ++i.

An example from Gauge.sol File: Gauge.sol#179-185

for (uint i = 0; i < numRewards; i++) {
            address token = sb.rewards(i);
            uint epochRewards = sb.deliverReward(token, bribeStart);
            if (epochRewards > 0) {
                _notifyBribeAmount(token, epochRewards, bribeStart);
            }
        }

Can be changed to

for (uint i = 0; i < numRewards;) { 
            address token = sb.rewards(i);
            uint epochRewards = sb.deliverReward(token, bribeStart);
            if (epochRewards > 0) {
                _notifyBribeAmount(token, epochRewards, bribeStart);
            }
            unchecked{
                ++i; //++i is cheaper than i++
            }
        }

Instances where this can be implented

• File: Gauge.sol#179-185
• File: Gauge.sol#353-362
• File: Gauge.sol#405-414
• File: Gauge.sol#426-429
• File: Gauge.sol#448-457
• File: Gauge.sol#484-492
• File: VotingEscrow.sol#632-663
• File: VotingEscrow.sol#886-897
• File: VotingEscrow.sol#942-953
• File: VotingEscrow.sol#1017-1031
• File: VotingEscrow.sol#1146-1149
• File: VotingEscrow.sol#1193-1197
• File: VotingEscrow.sol#1225-1230
• File: VotingEscrow.sol#1249-1252
• File: VotingEscrow.sol#1295-1300
• File: VotingEscrow.sol#1320-1328
• File: Voter.sol#76-78
• File: Voter.sol#103-117
• File: Voter.sol#143-166
• File: Voter.sol#266-274
• File: Voter.sol#304-312
• File: Voter.sol#340-348