Gas Optimizations

[code423n4]

1. Unnecessary initialising with default values

When variables are created it is assumed to contain default values, explicit initialising with default values (0, address(0), false, ...) is not necessary

Proof of concept

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VeAssetDepositor.sol#L28

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/Booster.sol#L110

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/BaseRewardPool.sol#L66-L72

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VoterProxy.sol#L227

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VeTokenMinter.sol#L61-L63

Mitigation

Avoid initilising variables with default values

2. boolean comparison

expression that returns boolean value can be directly used in conditions instead of comparing it with boolean constants

Proof of concept

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/Booster.sol#L352

    require(pool.shutdown == false, "pool is closed");

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/Booster.sol#L498

    require(pool.shutdown == false, "pool is closed");

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VoterProxy.sol#L70

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VoterProxy.sol#L110

Mitigation

The result of the statement can be used directly instead of comparing with boolean constants

3. > 0 can be replaced with != 0

!= 0 is more efficient than > 0 when used with unsigned integers in reqquire statements

Proof of concept

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VeAssetDepositor.sol#L132

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/BaseRewardPool.sol#L173

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/BaseRewardPool.sol#L196

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/BaseRewardPool.sol#L215

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VE3DRewardPool.sol#L210

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VE3DRewardPool.sol#L234

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VE3DRewardPool.sol#L253

Mitigation

> 0 can be replaced with != 0

4. Unnecessary variable

Results of expression that is used only once can be used directly in statements instead of storing in a variable

Proof of concept

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VeAssetDepositor.sol#L155

    bool depositOnly = _stakeAddress == address(0);
    if (depositOnly) {

Mitigation

The results can be used directly in the statements instead of storing in a variable

5. Cache storage read and save gas

When storage variables are read multiple times in the same function, it can be stored in a local variable and re-used instead of reading again from storage to save gas

Proof of concept

feeToken, lockFees, stakerLockRewards in

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/Booster.sol#L586-L592

Mitigation

Value read from storage can be stored in a local variable and re-used

6. for-loops can be optimized

In for-loops i++ can be replaced by ++i as it is cheaper and unchecked can be added to the incremented variable to save more gas, Variable initialising with default values can be avoided as it contains the value by default Array length can be cached in a local variables and used in the condition instead of querying length in every loop

Proof of concept

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/Booster.sol#L329

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

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/BaseRewardPool.sol#L176

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/BaseRewardPool.sol#L199

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/BaseRewardPool.sol#L218

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/BaseRewardPool.sol#L245

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/BaseRewardPool.sol#L282

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VE3DRewardPool.sol#L148

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VE3DRewardPool.sol#L214

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VE3DRewardPool.sol#L238

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VE3DRewardPool.sol#L257

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VE3DRewardPool.sol#L281

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VE3DRewardPool.sol#L325

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/VoterProxy.sol#L217

Mitigation

post-increment can be converted to pre-increment, avoid default value initialisation of incremented varaible, array length can be stored in a local variable and used in the conditional statement

7. Function signature can be directly used

In Booster#setGaugeRedirect.sol function selector in the abi.encodeWithSelector can be directly added in code instead of computing the hash

Proof of concept

https://github.com/code-423n4/2022-05-vetoken/blob/2d7cd1f6780a9bcc8387dea8fecfbd758462c152/contracts/Booster.sol#L488

    bytes memory data = abi.encodeWithSelector(
        bytes4(keccak256("set_rewards_receiver(address)")),
        stash
    );

Mitigation

The statement can be changed to

    bytes memory data = abi.encodeWithSelector(
        0xbdf98116,
        stash
    );

[GalloDaSballo]

Less than 500 gas saved