Gas Optimizations #223

code423n4 · 2022-05-30T19:57:33Z

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)

[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

The text was updated successfully, but these errors were encountered:

GalloDaSballo · 2022-06-30T01:23:22Z

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

Would save 120 gas and 90 gas per function call respectively

GalloDaSballo · 2022-06-30T01:24:37Z

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

51 entries per instance

[Gas-4] Potential usage of unchecked

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

Is no longer valid

Overall a neat report with an interesting find (5)
Would save 20 gas (at least) per instance
20 * 20 = 400

GalloDaSballo · 2022-06-30T01:24:53Z

Total Gas Saved
661

code423n4 added bug Something isn't working G (Gas Optimization) labels May 30, 2022

code423n4 added a commit that referenced this issue May 30, 2022

TerrierLover issue #223

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Gas Optimizations #223

Gas Optimizations #223

code423n4 commented May 30, 2022

GalloDaSballo commented Jun 30, 2022

GalloDaSballo commented Jun 30, 2022

GalloDaSballo commented Jun 30, 2022

Gas Optimizations #223

Gas Optimizations #223

Comments

code423n4 commented May 30, 2022

[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

GalloDaSballo commented Jun 30, 2022

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

GalloDaSballo commented Jun 30, 2022

[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

GalloDaSballo commented Jun 30, 2022

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