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

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Gas Optimizations #111

Open code423n4 opened 2 years ago

code423n4 commented 2 years ago

Variable can be constant

https://github.com/code-423n4/2022-05-cudos/blob/de39cf3cd1f1e1cf211819b06d4acf6a043acda0/solidity/contracts/CosmosToken.sol#L5-L6

    uint256 MAX_UINT = 2**256 - 1;

Variables can be immutable

https://github.com/code-423n4/2022-05-cudos/blob/de39cf3cd1f1e1cf211819b06d4acf6a043acda0/solidity/contracts/Gravity.sol#L59-L63

    // These are set once at initialization
    bytes32 public state_gravityId;
    uint256 public state_powerThreshold;

    CudosAccessControls public cudosAccessControls;

Cache state_lastEventNonce

Here is an example but there are multiple occurrence https://github.com/code-423n4/2022-05-cudos/blob/de39cf3cd1f1e1cf211819b06d4acf6a043acda0/solidity/contracts/Gravity.sol#L583-L592

Change the code into

        // LOGS scoped to reduce stack depth
        {
            uint 256 _state_lastEventNonce = state_lastEventNonce.add(1);
            state_lastEventNonce = _state_lastEventNonce;
            emit LogicCallEvent(
                _args.invalidationId,
                _args.invalidationNonce,
                returnData,
                _state_lastEventNonce
            );
        }

For loop optimization with ++i

using ++i save gas against i++

contracts/Gravity.sol:128:               for (uint256 i = 0; i < _users.length; i++) {
contracts/Gravity.sol:233:              for (uint256 i = 0; i < _currentValidators.length; i++) {
contracts/Gravity.sol:263:              for (uint256 i = 0; i < _newValset.validators.length; i++) {
contracts/Gravity.sol:453:                              for (uint256 i = 0; i < _amounts.length; i++) {
contracts/Gravity.sol:568:              for (uint256 i = 0; i < _args.transferAmounts.length; i++) {
contracts/Gravity.sol:579:              for (uint256 i = 0; i < _args.feeAmounts.length; i++) {
contracts/Gravity.sol:660:              for (uint256 i = 0; i < _powers.length; i++) {

For loop optimization by caching length

Cache array length to reduce MLOADs, e.g.

uint256 arrlen = _users.length;
for (uint256 i = 0; i < arrlen; i++)
contracts/Gravity.sol:128:               for (uint256 i = 0; i < _users.length; i++) {
contracts/Gravity.sol:233:              for (uint256 i = 0; i < _currentValidators.length; i++) {
contracts/Gravity.sol:263:              for (uint256 i = 0; i < _newValset.validators.length; i++) {
contracts/Gravity.sol:453:                              for (uint256 i = 0; i < _amounts.length; i++) {
contracts/Gravity.sol:568:              for (uint256 i = 0; i < _args.transferAmounts.length; i++) {
contracts/Gravity.sol:579:              for (uint256 i = 0; i < _args.feeAmounts.length; i++) {
contracts/Gravity.sol:660:              for (uint256 i = 0; i < _powers.length; i++) {

Unnecessary safe math

https://github.com/code-423n4/2022-05-cudos/blob/de39cf3cd1f1e1cf211819b06d4acf6a043acda0/solidity/contracts/Gravity.sol#L465-L466

contracts/Gravity.sol:349:              state_lastEventNonce = state_lastEventNonce.add(1);
contracts/Gravity.sol:465:                      state_lastEventNonce = state_lastEventNonce.add(1);
contracts/Gravity.sol:585:                      state_lastEventNonce = state_lastEventNonce.add(1);
contracts/Gravity.sol:601:              state_lastEventNonce = state_lastEventNonce.add(1);
contracts/Gravity.sol:621:              state_lastEventNonce = state_lastEventNonce.add(1);

Use separate require instead of &&

https://github.com/code-423n4/2022-05-cudos/blob/de39cf3cd1f1e1cf211819b06d4acf6a043acda0/solidity/contracts/Gravity.sol#L301-L307

        require(
            _currentValset.validators.length == _currentValset.powers.length &&
                _currentValset.validators.length == _v.length &&
                _currentValset.validators.length == _r.length &&
                _currentValset.validators.length == _s.length,
            "Malformed current validator set"
        );

Upgrade to latest Solidity

Consider upgrade to latest 0.8.12 for various gas saving