Here are Gas reports

[GAS-1] Use custom errors

Using custom errors can reduce the gas cost.

There are more than 100 callsites of require check with inline error message. Using the custom errors instead of the inline error messages can reduce the gas cost.

[GAS-2] Use `!= 0` instead of `> 0` on uint variables

uint variables will never be lower than 0. Therefore, > 0 and != 0 have same meanings. Using != 0 can reduce the gas deployment cost, so it is worth using != 0 wherever possible.

If the codebase uses > 0 on uint variables like this:

require(_amount > 0, "...");

it can rewrite like this:

require(_amount != 0, "...");

The above change can be applied to the following codes.

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Bribe.sol#L42 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Bribe.sol#L86 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Bribe.sol#L93 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Bribe.sol#L100

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/PairFees.sol#L20 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/PairFees.sol#L29-L30

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Router.sol#L58-L59

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L111 (This if statement seems not necessary since it checks _votes != 0)

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L167 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L227 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L239 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L259 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L289 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L294 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L322 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L352

[Gas-3] No need to set 0 on uint variables

The default value of uint varibles are 0. Therefore, there is no need to set 0 on uint variables. Not setting 0 on uint variables can reduce the gas cost.

If 0 is set on uint variable like this uint256 amount = 0;, it can rewrite to uint256 amount;. In for loop, if uint is used like this for (uint256 i = 0; i < length; i++), it can omit setting = 0 and will be for (uint256 i; i < length; i++).

The above change can be applied to the following codes.

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Gauge.sol#L179 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Gauge.sol#L353 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Gauge.sol#L481 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Gauge.sol#L551

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Minter.sol#L57

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Pair.sol#L20 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Pair.sol#L257 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Pair.sol#L273-L274 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Pair.sol#L389

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Router.sol#L90 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Router.sol#L316

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Velo.sol#L9

[Gas-4] Potential usage of unchecked

Following variables or operations can be wrapped by unchecked.

i++ or x++ https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Gauge.sol#L405

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Gauge.sol#L426

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Pair.sol#L389

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/RewardsDistributor.sol#L75

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/RewardsDistributor.sol#L105

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/RewardsDistributor.sol#L121

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/RewardsDistributor.sol#L148

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/RewardsDistributor.sol#L195

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L272

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Voter.sol#L340

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/VotingEscrow.sol#L632

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/VotingEscrow.sol#L886 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/VotingEscrow.sol#L942 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/VotingEscrow.sol#L1017

balance / DURATION

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Gauge.sol#L615

amount / DURATION https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Gauge.sol#L650
priceAverageCumulative / granularity https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Pair.sol#L260
y - y_prev and y_prev - y https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Pair.sol#L399-L407
temp /= 10, value /= 10 https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/VotingEscrow.sol#L138

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/VotingEscrow.sol#L144

[Gas-5] Avoid defining DOMAIN_SEPARATOR every time the functions are called

At folowing functions, they define DOMAIN_SEPARATOR every time the functions are called. DOMAIN_SEPARATOR can be set beforehand, and it can avoid defining DOMAIN_SEPARATOR every time.

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/Pair.sol#L468-L476

https://github.com/code-423n4/2022-05-velodrome/blob/main/contracts/contracts/VotingEscrow.sol#L1362-L1370

code-423n4 / 2022-05-velodrome-findings

Gas Optimizations #223

[GAS-1] Use custom errors

[GAS-2] Use `!= 0` instead of `> 0` on uint variables

[Gas-3] No need to set 0 on uint variables

[Gas-4] Potential usage of unchecked

[Gas-5] Avoid defining DOMAIN_SEPARATOR every time the functions are called

[Gas-5] Avoid defining DOMAIN_SEPARATOR every time the functions are called

[Gas-3] No need to set 0 on uint variables

[Gas-4] Potential usage of unchecked

[GAS-2] Use != 0 instead of > 0 on uint variables