Frankencoin - trysam2003's results

1. && costs more gas than a separate expression

The && operator is a logical AND operator that checks if both of its operands evaluate to true. Using the && operator can be more expensive regarding gas costs than using separate expressions because it requires additional computational overhead to evaluate the operands and check the result.

Proof of Concept

    84: if (_applicationPeriod < MIN_APPLICATION_PERIOD && totalSupply() > 0) revert PeriodTooShort();
    85: if (_applicationFee < MIN_FEE  && totalSupply() > 0) revert FeeTooLow();

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

2. X>0 consumes more gas than X!=0

This is because X>0 requires the EVM to perform an additional operation with 0, which can consume slightly more gas than the X!=0 operator, which simply checks whether the value is non-zero.

Proof of Concept

    104: if (explicit > 0)      

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

    203 if (challenge.bid > 0) {

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

3. x<=y consumes more gas than x>y. Also, x>=y consumes more gas than x<y

This is because the <= operator requires the EVM to perform an additional comparison operation to check if the value is equal, while the > operator only needs to check if the value is greater. This additional comparison operation can consume more gas and result in slightly higher gas costs.

Proof of Concept

    141: if (balance <= minReserve) 
    282:if (reserveLeft >= _amount)     

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

    171: require(challenge.size >= min);
    172: require(copy.size >= min);
    201: if (block.timestamp >= challenge.end) revert TooLate();
    218: if (earliestEnd >= challenge.end) {      

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

   184: if (time >= exp)
   305: if (block.timestamp >= expiration){
   374: if (block.timestamp <= cooldown) revert Hot();

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

   50:  require(block.timestamp <= horizon, "expired");

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