Frankencoin - petrichor's results

Gas Optmization

Summary

[G‑1] State variables should be cached in stack variables rather than re-reading them from storage

142     zchf.burnFrom(msg.sender, minted - newMinted, reserveContribution);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Position.sol#L142

143     minted = newMinted;

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Position.sol#L143

95      address(zchf),

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/MintingHub.sol#L95

107     zchf.registerPosition(address(pos));     

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/MintingHub.sol#L107

108     zchf.transferFrom(msg.sender, address(zchf.reserve()), OPENING_FEE);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/MintingHub.sol#L108

[G-2] >= casts less gas then >

84     if (_applicationPeriod < MIN_APPLICATION_PERIOD && totalSupply() > 0) revert PeriodTooShort();  

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L84

85     if (_applicationFee < MIN_FEE  && totalSupply() > 0) revert FeeTooLow();   

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L85

104    if (explicit > 0){   

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L104

153    if (block.timestamp > minters[_minter]) revert TooLate();    

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L153

203    if (challenge.bid > 0) {

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/MintingHub.sol#L203

267    if (effectiveBid > fundsNeeded){

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/MintingHub.sol#L267

115     if (amount > 0){

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Equity.sol#L115

[G-3]Avoid using state variable in emit

Using a state variable in SetOwner emits wastes gas.

69      emit PositionOpened(_owner, original, _zchf, address(collateral), _liqPrice);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Position.sol#L69

87      emit PositionOpened(owner, original, address(zchf), address(collateral), _price);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Position.sol#L87

287     emit MintingUpdate(collateralBalance(), price, minted, limit);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Position.sol#L87

[G-4]Use != 0 instead of > 0 for unsigned integer comparison

When dealing with unsigned integer types, comparisons with != 0 are cheaper then with > 0.

381     if (challengedAmount > 0) revert Challenged();

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Position.sol#L381

203       if (challenge.bid > 0) {

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/MintingHub.sol#L203

114     if (amount > 0){

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Equity.sol#L114

84      if (_applicationPeriod < MIN_APPLICATION_PERIOD && totalSupply() > 0) revert PeriodTooShort();

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L84

85      if (_applicationFee < MIN_FEE  && totalSupply() > 0) revert FeeTooLow();

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L85

[G-5]Change public state variable visibility to private

If it is preferred to change the visibility of the owner

21      address public owner; 

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Ownable.sol

[G-6]Amounts should be checked for 0 before calling a transfer

253     IERC20(token).transfer(target, amount);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Position.sol#L253

269     IERC20(collateral).transfer(target, amount);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Position.sol#L269

69     chf.transfer(target, amount);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/StablecoinBridge.sol#L69

280     zchf.transfer(target, proceeds);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Equity.sol#L280

[G-7] Using calldata instead of memory for read-only arguments in external functions saves gas

159     Challenge memory copy = Challenge(

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/MintingHub.sol#L159

[G-8] Make 3 event parameters indexed when possible

It's the most gas efficient to make up to 3 event parameters indexed. If there are less than 3 parameters, you need to make all parameters indexed.

92     event Trade(address who, int amount, uint totPrice, uint newprice); // amount pos or neg for mint or redemption

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Equity.sol#L92

52    event MinterApplied(address indexed minter, uint256 applicationPeriod, uint256 applicationFee, string message);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L52

53    event MinterDenied(address indexed minter, string message);

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L53

[G‑9] Use nested if statements instead of &&

85     if (_applicationPeriod < MIN_APPLICATION_PERIOD && totalSupply() > 0) revert PeriodTooShort();

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L85

86     if (_applicationFee < MIN_FEE  && totalSupply() > 0) revert FeeTooLow();

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L86

267     if (!isMinter(msg.sender) && !isMinter(positions[msg.sender])) revert NotMinter();

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Frankencoin.sol#L267

294     if (size < minimumCollateral && size < collateralBalance()) revert ChallengeTooSmall();

https://github.com/code-423n4/2023-04-frankencoin/blob/main/contracts/Position.sol#L294