search

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

0 stars 0 forks source link

Gas Optimizations #208

Open code423n4 opened 2 years ago

code423n4 commented 2 years ago

1. IT COSTS MORE GAS TO INITIALIZE VARIABLES TO ZERO THAN TO LET THE DEFAULT OF ZERO BE APPLIED

// Links to github files https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L68 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L94 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L95

// actual codes
 contracts/auth/AxelarAuthWeighted.sol:68:        uint256 totalWeight = 0;+
contracts/auth/AxelarAuthWeighted.sol:94:        uint256 operatorIndex = 0;
contracts/auth/AxelarAuthWeighted.sol:95:        uint256 weight = 0;

2. ARRAY .LENGTH SHOULD NOT BE LOOKED UP IN EVERY LOOP OF A FOR-LOOP

The overheads outlined below are PER LOOP, excluding the first loop storage arrays incur a Gwarmaccess (100 gas) memory arrays use MLOAD (3 gas) calldata arrays use CALLDATALOAD (3 gas). Caching the length changes each of these to a DUP (3 gas), and gets rid of the extra DUP needed to store the stack offset

// Links to githubfile 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 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L17 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L98 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L17 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

// actual codes
contracts/deposit-service/AxelarDepositService.sol:114:        for (uint256 i; i < refundTokens.length; i++) {
contracts/deposit-service/AxelarDepositService.sol:168:        for (uint256 i; i < refundTokens.length; i++) {
contracts/deposit-service/AxelarDepositService.sol:204:        for (uint256 i; i < refundTokens.length; i++) {
contracts/auth/AxelarAuthWeighted.sol:17:        for (uint256 i; i < recentOperators.length; ++i) {
contracts/auth/AxelarAuthWeighted.sol:98:        for (uint256 i = 0; i < signatures.length; ++i) 
contracts/AxelarGateway.sol:207:        for (uint256 i = 0; i < symbols.length; i++) 
contracts/gas-service/AxelarGasService.sol:123:        for (uint256 i; i < tokens.length; i++)
GalloDaSballo commented 2 years ago

Less than 100 gas saved