the solidity compiler will always read the length of the array during each iteration. That is,
1. if it is a storage array, this is an extra sload operation (100 additional extra gas (EIP-2929) for each iteration except for the first),
2. if it is a memory array, this is an extra mload operation (3 additional gas for each iteration except for the first),
3. if it is a calldata array, this is an extra calldataload operation (3 additional gas for each iteration except for the first)
This extra costs can be avoided by caching the array length (in stack):
uint length = arr.length; for (uint i = 0; i < length; i++) { // do something that doesn't change arr.length }
1. Caching the length in for loops
impact
the solidity compiler will always read the length of the array during each iteration. That is,
This extra costs can be avoided by caching the array length (in stack):
uint length = arr.length; for (uint i = 0; i < length; i++) { // do something that doesn't change arr.length }proof
https://github.com/code-423n4/2022-04-jpegd/blob/e72861a9ccb707ced9015166fbded5c97c6991b6/contracts/vaults/NFTVault.sol#L181
https://github.com/code-423n4/2022-04-jpegd/blob/e72861a9ccb707ced9015166fbded5c97c6991b6/contracts/vaults/yVault/strategies/StrategyPUSDConvex.sol#L145
2 .use of != for comparison instead of > 0
impact
!= 0 costs less gas compared to > 0 for in require statements
proof
https://github.com/code-423n4/2022-04-jpegd/blob/e72861a9ccb707ced9015166fbded5c97c6991b6/contracts/vaults/NFTVault.sol#L926