prePO contest - kenta's results

2022-03-prepo

1 import IERC20 instead of ERC20 in PrePOMarket.

https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/PrePOMarket.sol#L6

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

2 delete an unused import statement. IERC20 is never used in PrePOMarketFactory.

https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/PrePOMarketFactory.sol#L7

Delete it.

2022-03-prepo gas optimization

1 Use the initial value for uint256 and unchecked with prefix increment in loop

https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/AccountAccessController.sol#L44 https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/AccountAccessController.sol#L55

for (uint256 _i; _i < array.length;) { // some executions unchecked {++_i;} }

AccountAccessController.sol

2 Use prefix to add 1 into uint variables.

https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/AccountAccessController.sol#L35 https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/AccountAccessController.sol#L101

++_blockedAccountsIndex; ++_allowedAccountsIndex;

CollateralDepositRecord.sol

3 Use uncheck in recordWithdrawal. In if sentence underflow is already checked, so you can use unchecked to save gas cost.

https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/CollateralDepositRecord.sol#L47 https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/CollateralDepositRecord.sol#L52

unchecked { _globalDepositAmount -= _amount; }

unchecked { _accountToNetDeposit[_sender] -= _amount; } DepositHook.sol

4 Use immutable for _accountAccessController and _depositRecord. There is no setter for these state variables. With immutable, you can save gas costs.

https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/DepositHook.sol#L11-L12

IAccountAccessController private immutable _accountAccessController; ICollateralDepositRecord private immutable _depositRecord;

WithdrawHook.sol

5 Use immutable for _depositRecord. There is no setter for this state variable. With immutable, you can save gas costs.

https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/WithdrawHook.sol#L10

PrePOMarket.sol

6 use unchecked in redeem. The possibility of underflow is already checked with if sentence(_finalLongPrice <= MAX_PRICE), so you can use unchecked to save gas cost.

https://github.com/code-423n4/2022-03-prepo/blob/main/contracts/core/PrePOMarket.sol#L145-L146

uint256 _shortPrice; unchecked { shortPrice = MAX_PRICE - _finalLongPrice; }