Cache array length in for loops can save gas

[code423n4]

Handle

defsec

Vulnerability details

Impact

Reading array length at each iteration of the loop takes 6 gas (3 for mload and 3 to place memory_offset) in the stack.

Caching the array length in the stack saves around 3 gas per iteration.

Proof of Concept

1. Navigate to the following smart contract line.

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/callManagers/RebalanceManager.sol#L218

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/callManagers/RebalanceManager.sol#L234

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/callManagers/RebalanceManagerV2.sol#L155

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/callManagers/RebalanceManagerV3.sol#L166

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/factories/PieFactoryContract.sol#L88

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Call/CallFacet.sol#L55

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L50

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L160

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L321

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L348

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L381

https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/singleJoinExit/SingleNativeTokenExit.sol#L69

Tools Used

None

Recommended Mitigation Steps

Consider to cache array length.

[0xleastwood]

Duplicate of #249