Phuture Finance contest - rfa's results

Gas

Title: Using < is less effective than !=

Occurence: https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/ChainlinkPriceOracle.sol#L86 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/IndexLogic.sol#L76 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/IndexLogic.sol#L98

Instead of using > as operator for validate value is not zero, Using =! Is more effective for gas optimization.

Title: Using && is less effective than using multiple require()

Occurence: https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/ChainlinkPriceOracle.sol#L86 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/ChainlinkPriceOracle.sol#L86 Using && operator cost more execution gas fee. Use multiple require checks to save gas https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/ManagedIndexReweightingLogic.sol#L29-L34

Change to:

        require(basePrice > 0, "ChainlinkPriceOracle: NEGATIVE");
        require(quotePrice > 0, "ChainlinkPriceOracle: NEGATIVE");

Title: Using custom error Occurence: https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/BaseIndex.sol#L29 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/BaseIndex.sol#L34 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/ChainlinkPriceOracle.sol#L51 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/ChainlinkPriceOracle.sol#L61-L62 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/IndexLogic.sol#L40 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/IndexLogic.sol#L76 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/IndexLogic.sol#L98 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/ManagedIndexReweightingLogic.sol#L29-L34 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/ManagedIndexReweightingLogic.sol#L52 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/ManagedIndexReweightingLogic.sol#L58 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/PhuturePriceOracle.sol#L46-L47 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/TopNMarketCapIndex.sol#L55 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/TopNMarketCapReweightingLogic.sol#L67

Defined by using error statement, and using if(condition)revert() to check the condition. It can be implemented for all require() statement for gas opt.

Title: Using unchecked for ++i

https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/IndexLogic.sol#L60 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/IndexLogic.sol#L102 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/IndexLogic.sol#L125 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/ManagedIndex.sol#L30 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/TopNMarketCapIndex.sol#L48 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/TopNMarketCapReweightingLogic.sol#L51 https://github.com/code-423n4/2022-04-phuture/blob/main/contracts/TopNMarketCapReweightingLogic.sol#L37

Its almost impossible for i to overflow. Using unchecked can save execution gas cost Change to:

	for (uint i; i < inactiveAssets.length(); ++i) {
            if (!IAccessControl(registry).hasRole(SKIPPED_ASSET_ROLE, inactiveAssets.at(i))) {
                uint lastBalanceInAsset = IvToken(
                    IvTokenFactory(vTokenFactory).createOrReturnVTokenOf(inactiveAssets.at(i))
                ).lastAssetBalanceOf(address(this));
                lastAssetBalanceInBase += lastBalanceInAsset.mulDiv(
                    FixedPoint112.Q112,
                    oracle.refreshedAssetPerBaseInUQ(inactiveAssets.at(i))
                );
            }
	unchecked{++i} // @audit-info: Add here
        }