Gas Optimizations

[code423n4]

1. In processWithdrawals function at VUSD.sol#L64, modify i+=1 to ++i

2. In processWithdrawals function at VUSD.sol#L63, use unchecked at reserve -= withdrawal.amount; since we already know that reserve > withdrawal.amount

3. In withdraw function at VUSD.sol#L48, add a check require(amount!=0, "Invalid amount");

4. In mintWithReserve function at VUSD.sol#L43, add below require

require(amount!=0, "Invalid amount");
require(to!=address(0), "Invalid address");

5. getRoundData function at Oracle.sol#L124 is not required. Simply change the if(latestPrice < 0) to while(latestPrice < 0) at Oracle.sol#L117 which will eliminate the need of getRoundData function

function getLatestRoundData(AggregatorV3Interface _aggregator)
        internal
        view
        returns (
            uint80,
            uint256 finalPrice,
            uint256
        )
    {
        (uint80 round, int256 latestPrice, , uint256 latestTimestamp, ) = _aggregator.latestRoundData();
        finalPrice = uint256(latestPrice);
        while (latestPrice < 0) {
            requireEnoughHistory(round);
            (round, finalPrice, latestTimestamp) = getRoundData(_aggregator, round - 1);
        }
        return (round, finalPrice, latestTimestamp);
    }

6. In deposit function at InsuranceFund.sol#L39, add a condition require(amount!=0, "Invalid amount")

7. In withdraw function at InsuranceFund.sol#L62, add a check require( _shares!=0,"Invalid shares");

8. In liquidate function at ClearingHouse.sol#L140, updatePositions function is not required since this is already called in _liquidateMaker and _liquidateTaker function

9. In addMarginFor function at MarginAccount.sol#L149, add new check

require(idx >= supportedCollateral.length,"Invalid index");

10. In removeMargin function at MarginAccount.sol#L177, margin[idx][trader] -= amount.toInt256(); can be unchecked since contract has already checked margin[idx][trader] >= amount.toInt256()

11. In removeMargin function at MarginAccount.sol#L168, add a check require(amount!=0,"Invalid amount");

12. In settleBadDebt function at MarginAccount.sol#L362, modify require(vusdBal < 0, "Nothing to repay"); to require(vusdBal <= 0, "Nothing to repay"); since if vusdBal is 0 then also there is nothing to repay

13. In weightedAndSpotCollateral function at MarginAccount.sol#L524 add a check to see margin[i][trader]==0 as shown below

function weightedAndSpotCollateral(address trader)
        public
        view
        returns (int256 weighted, int256 spot)
    {
        ...

        for (uint i = 0; i < assets.length; i++) {
            _collateral = assets[i];
  if(margin[i][trader]==0){continue}
            int numerator = margin[i][trader] * oracle.getUnderlyingPrice(address(assets[i].token));
            ...
        }
    }

14. In liquidateFlexible function at MarginAccount.sol#L328, before entering loop check if trader can be liquidated

function liquidateFlexible(address trader, uint maxRepay, uint[] calldata idxs) external whenNotPaused {
        clearingHouse.updatePositions(trader); // credits/debits funding
(buffer.status, buffer.repayAble, buffer.incentivePerDollar) = isLiquidatable(trader, false);
if (buffer.status != IMarginAccount.LiquidationStatus.IS_LIQUIDATABLE) {return}

for (uint i = 0; i < idxs.length; i++){
        ...
    }

[atvanguard]

Good suggestion.

[moose-code]

Some nice less generic suggestions 👍