Gas Optimizations - Githubissues

code423n4 commented 2 years ago

2022-03-Li.finance gas optimization

1 use unchecked and prefix for loop

For example,

for (uint8 i; i < _swapData.length;) { // some executions

unchecked {
    ++i;
}

}

2 == true is unnecessary in require.

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/Swapper.sol#L16

require( ls.dexWhitelist[_swapData[i].approveTo] && ls.dexWhitelist[_swapData[i].callTo], "Contract call not allowed!" )

3 use unchecked. Underflow will not happen in the following part because of an increase in the balance.

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Libraries/LibSwap.sol#L48

unchecked { toAmount = LibAsset.getOwnBalance(_swapData.receivingAssetId) - toAmount; }

4 use unchecked. Underflow is already checked in if statement before the following line. Since Solidity 0.8.0, all arithmetic operations revert on over- and underflow by default, thus making the use of these libraries unnecessary. To obtain the previous behaviour, an unchecked block can be used and this is cheaper from the view of gas.

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/NXTPFacet.sol#L166

Unchecked { finalBalance = postSwapBalance - startingBalance; }

5 use memory instead of storage and you don’t need to call getStorage() to get s.cBridge, so you don’t use _bridge()any more. You can delete this function and save deployment costs.

https://github.com/code-423n4/2022-03-lifinance/blob/699c2305fcfb6fe8862b75b26d1d8a2f46a551e6/src/Facets/CBridgeFacet.sol#L143-L144

Storage memory s = getStorage();

    // Do CBridge stuff
    require(s.cBridgeChainId != _cBridgeData.dstChainId, "Cannot bridge to the same network.");

    if (LibAsset.isNativeAsset(_cBridgeData.token)) {
        ICBridge(s.cBridge).sendNative(
            _cBridgeData.receiver,
            _cBridgeData.amount,
            _cBridgeData.dstChainId,
            _cBridgeData.nonce,
            _cBridgeData.maxSlippage
        );
    } else {
        // Give CBridge approval to bridge tokens
        LibAsset.approveERC20(IERC20(_cBridgeData.token), s.cBridge, _cBridgeData.amount);
        // solhint-disable check-send-result
        ICBridge(s.cBridge).send(
            _cBridgeData.receiver,
            _cBridgeData.token,
            _cBridgeData.amount,
            _cBridgeData.dstChainId,
            _cBridgeData.nonce,
            _cBridgeData.maxSlippage
        );
    }

and delete _bridge()in CBridgeFacet.sol.

6 Don’t use == (equality) to save gas. The following lines use == (equality) for boolean. You don’t need this syntax to check boolean.

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/DexManagerFacet.sol#L20 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/DexManagerFacet.sol#L34

For example,

if (s.dexWhitelist[_dex]){}

7 Use ! instead of == false. ! must be cheaper than == false.

https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/DexManagerFacet.sol#L47 https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/DexManagerFacet.sol#L66

if (!s.dexWhitelist[_dex)