Swivel v3 contest - CRYP70's results

Hello! CRYP70 here and I appreciate the opportunity to be apart of this competition. I believe I have found something which may save you some gas over large arrays. See the details of my findings.

++i generally costs less gas than i++ or i = i + 1 (about 5 units per increment) because i++ must increment a value and then "return" the old value which means the program may need to hold two numbers in memory. When ++i is used, it will only ever use one number in memory.

See the example below for an simplified illustration:

pragma solidity ^0.8.13;

contract MyFavouriteCounter {
 
    uint public count;

    function incrementPrefixCount() public returns (uint) {
        count = 1;
        return (++count); // returns 2
    }
    
    function incrementPostfixCount() public returns (uint) {
        count = 1;
        return (count++); // returns 1
    }
}

I was able to identify this in the following locations:

Swivel.sol:100:initiate() - unchecked {i++;} Swivel.sol:269:exit() - unchecked {i++;} Swivel.sol:418:cancel() - i++; Swivel.sol:564:approveUnderlying() - i++;

Remediation: Simply using ++i can save some gas.

Thanks again!