search

code-423n4 / 2022-07-axelar-findings

0 stars 0 forks source link

Gas Optimizations #224

Open code423n4 opened 2 years ago

code423n4 commented 2 years ago
  1. use abi.encodepacked for gas optimization

Changing the abi.encode function to abi.encodePacked can save gas since the abi.encode function pads extra null bytes at the end of the call data, which is unnecessary. Also, in general, abi.encodePacked is more gas-efficient.

POC :

https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/AxelarGateway.sol#L566 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/AxelarGateway.sol#L580

  1. Use Custom Error instead of Revert / Require String to Save Gas

Custom error from solidity 0.8.4 are cheaper than revert strings, custom error are defined using the error statement can use inside and outside the contract.

source https://blog.soliditylang.org/2021/04/21/custom-errors/

i suggest replacing revert / require error strings with custom error.

POC :

https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L55 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L56 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L57 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L58 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L61 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L62 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L68 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L70 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L78 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L79 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L84 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L85 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L86 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L98 https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L111

  1. ++i costs less gas tha i++, especially when it's used in for-loops

save 6 gas per loop

POC :

https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/AxelarGateway.sol#L207 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/gas-service/AxelarGasService.sol#L123 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/AxelarDepositService.sol#L114 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/AxelarDepositService.sol#L168 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/AxelarDepositService.sol#L204

  1. useage of uint / int smaller than 32 bytes incurs overhead

When using elements that are smaller than 32 bytes, your contract’s gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller than that, the EVM must use more operations in order to reduce the size of the element from 32 bytes to the desired size.

POC :

https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/AxelarGateway.sol#L332 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L14

GalloDaSballo commented 2 years ago

use abi.encodepacked for gas optimization

There are security concerns, also would be surprised if abi.encode is the more expensive one (word math is cheaper)

In total report saves less than 50 gas