PoolTogether TWAB Delegator contest - IllIllI's results

Using bools for storage incurs overhead

    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/58f635312aa21f947cae5f8578638a85aa2519f5/contracts/security/ReentrancyGuard.sol#L23-L27

mapping(address => mapping(address => bool)) internal representatives;         

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/TWABDelegator.sol#L159

Functions not called by the contract itself should be external rather than public

function initialize(uint96 _lockUntil) public {           

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/Delegation.sol#L29

Using > 0 costs more gas than != 0 when used on uints in a require() statement

require(_amount > 0, "TWABDelegator/amount-gt-zero");            

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/TWABDelegator.sol#L601

<array>.length should not be looked up in every loop of a for-loop

Even memory arrays incur the overhead of bit tests and bit shifts to calculate the array length

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

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/PermitAndMulticall.sol#L33

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

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/Delegation.sol#L42

++i/i++ should be unchecked{++i}/unchecked{++i} when it is not possible for them to overflow, as is the case when used in for- and while-loops

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

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/PermitAndMulticall.sol#L33

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

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/Delegation.sol#L42

++i costs less gas than ++i, especially when it's used in for-loops (--i/i-- too)

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

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/PermitAndMulticall.sol#L33

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

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/Delegation.sol#L42

It costs more gas to initialize variables to zero than to let the default of zero be applied

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

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/PermitAndMulticall.sol#L33

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

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/Delegation.sol#L42

It costs less gas to inline the code of functions that are only called once

Doing so saves the cost of allocating the function selector, and the cost of the jump when the function is called.

  function _requireDelegatorNotZeroAddress(address _delegator) internal pure {
    require(_delegator != address(0), "TWABDelegator/dlgtr-not-zero-adr");
  }

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/TWABDelegator.sol#L608-L610

Using stack copies of variables when repeated access is required uses less gas

Even memory arrays incur the overhead of bit tests and bit shifts to calculate the array length. calls.length can be cached

    bytes[] memory response = new bytes[](calls.length);
    for (uint256 i = 0; i < calls.length; i++) {

https://github.com/pooltogether/v4-twab-delegator/blob/2b6d42506187dd7096043e2dfec65fa06ab18577/contracts/Delegation.sol#L41-L42