Gas Optimizations

[code423n4]

1. considered using require instead of && can save gas https://github.com/code-423n4/2022-02-nested/blob/main/contracts/FeeSplitter.sol#L123 // gas cost 35473

Change to:

require(accountsLength != 0);
require (accountsLength == _weights.length, "FS: INPUTS_LENGTH_MUST_MATCH");

// gas cost 35465

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2. considered add unchecked can save gas https://github.com/code-423n4/2022-02-nested/blob/main/contracts/FeeSplitter.sol#L327 // gas cost 22798

add unchecked

unchecked {
return (_amount * _weight) / _totalWeights;
}

// gas cost 22440

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3. avoid unnecessary i = 0 because the default of uint is already 0 https://github.com/code-423n4/2022-02-nested/blob/main/contracts/FeeSplitter.sol#L126

considered removing 0 value can save gas

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4. SafeERC20 Gas Optimization https://github.com/code-423n4/2022-02-nested/blob/main/contracts/NestedFactory.sol#L19 by not declaring this

   using SafeERC20 for IERC20;

and for example, use this:

SafeERC20.safeTransfer(IERC20(_inputToken)_msgSender(), _amountToSpend - amounts[1]);

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5. just read it directly to storage can save gas https://github.com/code-423n4/2022-02-nested/blob/main/contracts/FeeSplitter.sol#L279 // gas cost 24794

Change to:

Shareholder[] storage shareholdersCache = shareholders;

// gas cost 24684

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6. the original function will return 0 which a default value for uint256 https://github.com/code-423n4/2022-02-nested/blob/main/contracts/FeeSplitter.sol#L216 // gas cost 24940

Change to:

     function getAmountDue(address _account, IERC20 _token) public view returns (uint256) {
        TokenRecords storage _tokenRecords = tokenRecords[address(_token)];
        if (_tokenRecords.totalShares != 0) {

        uint256 totalReceived = _tokenRecords.totalReleased + _token.balanceOf(address(this));
        return
            (totalReceived * _tokenRecords.shares[_account]) /
            _tokenRecords.totalShares -
            _tokenRecords.released[_account];
        }
    }

// gas cost 24919

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[adrien-supizet]

1. confirmed
2. already acknowledged in the first audit -> disputed
3. disputed, this change makes no difference
4. confirmed, see POC: e59dfe4dd55326867489fbd2ef53899a56eb37d4
5. disputed, this actually increases gas consumption
6. acknowledged

[harleythedogC4]

My personal judgments:

1. "considered using require instead of && can save gas". Valid and small-optimization.
2. "considered add unchecked can save gas". Agree with sponsor. Invalid.
3. "avoid unnecessary i = 0 because the default of uint is already 0". This arose in the previous contest. Invalid.
4. "SafeERC20 Gas Optimization". Valid and small-optimization.
5. "just read it directly to storage can save gas". Seems like it can either decrease or increase gas usage depending on the array. Invalid.
6. "the original function will return 0 which a default value for uint256". Valid and small-optimization.

[harleythedogC4]

Now, here is the methodology I used for calculating a score for each gas report. I first assigned each submission to be either small-optimization (1 point), medium-optimization (5 points) or large-optimization (10 points), depending on how useful the optimization is. The score of a gas report is the sum of these points, divided by the maximum number of points achieved by a gas report. This maximum number was 10 points, achieved by #67.

The number of points achieved by this report is 3 points. Thus the final score of this gas report is (3/10)*100 = 30.