Gas Optimizations

[code423n4]

for loop optimisations

description

Uninitialized variables are assigned with the types default value.

Explicitly initializing a variable with it's default value costs unnecesary gas.

Suggest not initializing the for loop counter to 0.

An array’s length should be cached to save gas in for-loops

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.

Suggest storing the array’s length in a variable before the for-loop, and use it instead:

++i costs less gas compared to i++

++i costs less gas compared to i++ for unsigned integer, as pre-increment is cheaper (about 5 gas per iteration)

Suggest using ++i instead of i++ to increment the value of an uint variable.

Increments can be unchecked

In Solidity 0.8+, there’s a default overflow check on unsigned integers. It’s possible to uncheck this in for-loops and save some gas at each iteration, but at the cost of some code readability, as this uncheck cannot be made inline.

taking all of the above, the recommended format for gas savings is

for (uint256 i; i < numIterations;) {  
 // ...  
 unchecked { ++i; }  
}  

findings

https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/NestedFactory.sol#L124 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/NestedFactory.sol#L136 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/NestedFactory.sol#L196 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/NestedFactory.sol#L256 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/NestedFactory.sol#L315 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/NestedFactory.sol#L333 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/NestedFactory.sol#L369 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/NestedFactory.sol#L412 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/NestedFactory.sol#L651 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/OperatorResolver.sol#L40 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/OperatorResolver.sol#L60 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/OperatorResolver.sol#L75 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/abstracts/MixinOperatorResolver.sol#L37 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/abstracts/MixinOperatorResolver.sol#L56 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/operators/Beefy/BeefyVaultOperator.sol#L18 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/operators/Beefy/lp/BeefyZapBiswapLPVaultOperator.sol#L27 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/operators/Beefy/lp/BeefyZapUniswapLPVaultOperator.sol#L27 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/operators/Yearn/YearnCurveVaultOperator.sol#L42 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/governance/TimelockControllerEmergency.sol#L84 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/governance/TimelockControllerEmergency.sol#L89 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/governance/TimelockControllerEmergency.sol#L234 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/governance/TimelockControllerEmergency.sol#L324 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/governance/scripts/OperatorScripts.sol#L67 https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/governance/scripts/OperatorScripts.sol#L80

use shift operator

description

Gas can be saved by using >> operator instead of dividing by 2

use >> operator

findings

https://github.com/code-423n4/2022-06-nested/blob/b4a153c943d54755711a2f7b80cbbf3a5bb49d76/contracts/operators/Beefy/lp/BeefyZapBiswapLPVaultOperator.sol#L275

[Yashiru]

Use shift operator (Duplicated)

Duplicated of #89 at Use Shift Right/Left instead of Division/Multiplication

[Yashiru]

For loop optimizaion

++i costs less gas compared to i++ (Disputed)

Already surfaced in previous audit and mentioned in README.md

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An array’s length should be cached to save gas in for-loops (Disputed)

Already surfaced in previous audit and mentioned in README.md

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Increments can be unchecked (Disputed)

Already surfaced in previous audit here.

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Explicitly initializing a variable with it's default value costs unnecesary gas (Disputed)

Already surfaced in previous audit here.