GalloDaSballo
commented
2 years ago State variables that could be declared constant
3 * 2100 = 6300
Functions that can be external instead of public
Will not save gas
Use the external state visibility for functions that are never called from the contract.
Will not save gas
Ordering of structs
Valid but no poc on gas saved so 0
Use of Safemath
No deets on how this save gas
Total Gas saved 6300
Would recommend the warden to check their report on a MD previewer to make it look slightly better
Summary
During the code review, we found that few state variables that were declared as
privatecould be marked asconstantas they were not expected to be updated. Constant variables consume lesser gas than private variables. Also, we found a few functions that were declared as public but were never internally used. Such functions can always be marked asexternalinstead ofpublicasexternalfunctions consume lesser gas in comparison topublicfunctions. It was also noticed that the ordering of variables in structs was in random order. Structs perform variable packing, and hence it is recommended to go from lower bytes to higher bytes as the lower bytes get packed together to save gas. The contract was also found to be using the safeMath library, which is redundant if version solidity compiler version 0.8.0 and above is used as it has enough built-in features to prevent buffer overflow attacks and perform safer arithmetic calculations. It is advised to remove the safeMath library as they are super expensive in terms of gas consumption.Title:
State variables that could be declared constant
Description:
Constant state variables should be declared constant to save gas.
PoC:
The below variables
concurPerBlock_concurShareMultiplier_perMillecan be used as constants instead of private. https://github.com/code-423n4/2022-02-concur/blob/main/contracts/MasterChef.sol#L50 https://github.com/code-423n4/2022-02-concur/blob/main/contracts/MasterChef.sol#L56 https://github.com/code-423n4/2022-02-concur/blob/main/contracts/MasterChef.sol#L57Suggested Fix:
concurPerBlock_concurShareMultiplier_perMillecan be used as constants instead of private to save gas.Title:
Functions that can be external instead of public
Description:
Public functions that are never called by a contract should be declared external in order to conserve gas.
Impact
Smart Contracts are required to have effective Gas usage as they cost real money, and each function should be monitored for the amount of gas it costs to make it gas efficient.
Publicfunctions cost more Gas thanexternalfunctions.PoC:
The following functions can be declared external: https://github.com/code-423n4/2022-02-concur/blob/main/contracts/ConvexStakingWrapper.sol#L93-L118 https://github.com/code-423n4/2022-02-concur/blob/main/contracts/MasterChef.sol#L86-L101 https://github.com/code-423n4/2022-02-concur/blob/main/contracts/MasterChef.sol#L127-L132
Suggested Fix:
Use the
externalstate visibility for functions that are never called from the contract.Title:
Ordering of structs
Description:
Structs are packed, and arrangement matters for packing, which in turn affects the gas used. The ordering should be from lower to higher space consumption so packing can be done.
PoC:
Suggested Fix:
Use the ordering as below, switching
depositFeeBPto 2nd place instead of last.IERC20 depositToken; // Address of LP token contract. uint16 depositFeeBP; // Deposit fee in basis points uint allocPoint; // How many allocation points assigned to this pool. to distribute per block. uint lastRewardBlock; // Last block number that distribution occurs. uint accConcurPerShare; // Accumulated per share, times multiplier. See below.
Title:
Use of Safemath
Description:
Safemath module is considered very gas expensive. It was useful before solidity 0.8.0. After the 0.8.0 version, solidity auto handles buffer overflow, and hence safeMath can be avoided.
PoC:
The
MasterChef.solfile is using safeMath which is https://github.com/code-423n4/2022-02-concur/blob/main/contracts/MasterChef.sol#L10Suggested Fix:
Avoid using safeMath module to save gas