Removal of last token in the array can be optimized

[code423n4]

Handle

0xRajeev

Vulnerability details

Impact

The removal of the last token in the array can be optimized by checking if index == k-1, i.e. last element match, when there is no need to copy and simply popping will do. This will avoid the copy which involves several SLOADs/SSTOREs.

Proof of Concept

https://github.com/code-423n4/2021-09-yaxis/blob/cf7d9448e70b5c1163a1773adb4709d9d6ad6c99/contracts/v3/Manager.sol#L485

https://github.com/code-423n4/2021-09-yaxis/blob/cf7d9448e70b5c1163a1773adb4709d9d6ad6c99/contracts/v3/Harvester.sol#L141

Tools Used

Manual Analysis

Recommended Mitigation Steps

Example: Check if index != k-1 for tokens[_vault][index] = tokens[_vault][k-1];

[GalloDaSballo]

Agree with sponsor and severity, wouldn't mind not mitigating as it's very minor