Fraxlend (Frax Finance) contest - chrisdior4's results

<X> += <Y> COSTS MORE GAS THAN <X> = <X> + <Y> FOR STATE VARIABLES



There are 2 instances of this issue: 
=================
 file: FraxlendPairCore.sol




_totalBorrow.amount += uint128(_interestEarned);
 _totalAsset.amount += uint128(_interestEarned);




https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendPairCore.sol#L475
https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendPairCore.sol#L476




Should be:


_totalBorrow.amount = _totalBorrow.amount + uint128(_interestEarned);
 _totalAsset.amount = _totalAsset.amount + uint128(_interestEarned); 
=================

++i COSTS LESS GAS THAN i++, ESPECIALLY WHEN IT’S USED IN FOR-LOOPS



There are 4 instances of this issue: 

======================
 file: FraxlendPair.sol



for (uint256 i = 0; i < _lenders.length; i++) 
for (uint256 i = 0; i < _borrowers.length; i++)



https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendPair.sol#L289
https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendPair.sol#L308 
 Should be: 


for (uint256 i = 0; i < lendersLength; ++i) 
for (uint256 i = 0; i < borrowersLength; ++i) 

 ===================


File: FraxlendPairDeployer.sol



addresses[i] = deployedPairsByName[_deployedPairsArray[i]]; unchecked { i++;



https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendPairDeployer.sol#L130



Should be:


addresses[i] = deployedPairsByName[_deployedPairsArray[i]]; unchecked { ++i; ==================

 file: FraxlendWhitelist.sol



for (uint256 i = 0; i < _addresses.length; i++) {



https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendWhitelist.sol#L51



Should be:


for (uint256 i = 0; i < _addresses.length; ++i) {


<ARRAY>.LENGTH SHOULD NOT BE LOOKED UP IN EVERY LOOP OF A FOR-LOOP



There are 3 instances of this issue:



======================


File: FraxlendPair.sol



for (uint256 i = 0; i < _lenders.length; i++) 
 for (uint256 i = 0; i < _borrowers.length; i++) 

https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendPair.sol#L289
https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendPair.sol#L308



Should create new state variable then use it in the for loop:



uint256 lendersLength = _lenders.length;
 for(uint256. i =0; i < lendersLength; ++i)



uint256 borrowersLength = _borrowers.length; 
for(uint256. i =0; i < borrowersLength; ++i) 

=======================


File: FraxlendWhitelist.sol



for (uint256 i = 0; i < _addresses.length; i++) {

https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendWhitelist.sol#L51



Should create new state variable then use it in the for loop:



uint256 addressesLength = _addresses.length;
for (uint256 i = 0; i < addressesLength; ++i {


USING STORAGE INSTEAD OF MEMORY FOR STRUCTS/ARRAYS SAVES GAS


There are 3 instances of this issue: 
=========================


File: FraxlendPairCore.sol

address[] memory _path



https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendPairCore.sol#L1067



Should be: 
 address[] storage _path

File: FraxlendPairDeployer.sol



string[] memory _deployedPairsArray = deployedPairsArray; address[] memory _addresses = new address;



https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendPairDeployer.sol#L123
 https://github.com/code-423n4/2022-08-frax/blob/c4189a3a98b38c8c962c5ea72f1a322fbc2ae45f/src/contracts/FraxlendPairDeployer.sol#L125



Should be:


string[] storage _deployedPairsArray = deployedPairsArray; address[] storage _addresses = new address; =========================