Gas Optimizations

[code423n4]

Gas opt
#1 Using == true cost more gas
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/Swapper.sol#L16
Using == true to validate bool variable is unnecessary:

require(ls.dexWhitelist[_swapData[i].approveTo]);

#2 Using && in require() can cost more execution gas fee
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/Swapper.sol#L15-L18
Using multiple require() can save execution gas:

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

#3 Using unchecked and prefix increment for loop increment
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/Swapper.sol#L14
Using unchecked can save gas:

for (uint8 i; i < _swapData.length) {
            require(
                ls.dexWhitelist[_swapData[i].approveTo] == true && ls.dexWhitelist[_swapData[i].callTo] == true,
                "Contract call not allowed!"
            );
Unchecked{++i}

#4 Relocate the toAmount var declaration location
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Libraries/LibSwap.sol#L31
Declare the var at L48, then put the value LibAsset.getOwnBalance(_swapData.receivingAssetId) replacing toAmount. Remove L31

uint toAmount = LibAsset.getOwnBalance(_swapData.receivingAssetId) - LibAsset.getOwnBalance(_swapData.receivingAssetId);

#5 Using parameter to emit event
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/CBridgeFacet.sol#L47
Instead of reading from storage to get s.cBridge and s.cBridgeChainId value, using _cBridge and _chainId to emit can save gas

#6 Unnecessary _sendingAssetIdBalance var declaration
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/NXTPFacet.sol#L54-L57
_sendingAssetIdBalance was only called once in the contract. Caching LibAsset.getOwnBalance(sendingAssetId) into memory is consuming gas. I recommend just put it directly at L57

require(
                LibAsset.getOwnBalance(sendingAssetId) - LibAsset.getOwnBalance(sendingAssetId) ==  _nxtpData.amount,
                "ERR_INVALID_AMOUNT"
            );

Same case at:
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/NXTPFacet.sol#L91

#7 Using calldata on struct parameter
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/Swapper.sol#L12
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/AnyswapFacet.sol#L35
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/AnyswapFacet.sol#L75
Using calldata to store struct data type (LifiData) can save gas

#8 != more effective than <
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/AnyswapFacet.sol#L92
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/AnyswapFacet.sol#L105
Using != to validate than value is not 0 is gas saving

#9 Using unchecked on calculating finalBalance
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/NXTPFacet.sol#L166
The calculation of finalBalance won't underflow because of the if condition at L165. Using unchecked will save gas:

Unchecked{
finalBalance = postSwapBalance - startingBalance;
}

#10 Unnecessary receivingAssetIdBalance MSTORE
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/GenericSwapFacet.sol#L23
receivingAssetIdBalance var was merely called once in the function. Just pass LibAsset.getOwnBalance(_lifiData.receivingAssetId) value directly to L28:

uint256 postSwapBalance = LibAsset.getOwnBalance(_lifiData.receivingAssetId) - LibAsset.getOwnBalance(_lifiData.receivingAssetId);

#11 Custom errors from Solidity 0.8.4 are cheaper than revert strings
By defined using error statement, and using if(condition)revert() to check the condition. It can be implemented for all require() check

#12 Function can set external
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/AnyswapFacet.sol#L35
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/AnyswapFacet.sol#L78
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/CBridgeFacet.sol#L57
https://github.com/code-423n4/2022-03-lifinance/blob/main/src/Facets/CBridgeFacet.sol#L96
Some function can set external to save gas

[H3xept]

Re Function can set external

Duplicate of #197

[H3xept]

Re Redundant literal boolean comparisons

Duplicate of #39

[H3xept]

Re != more effective than <

Duplicate of #100

[H3xept]

Re unchecked operations

We internally decided to avoid unchecked operations for now.

[H3xept]

Re prefix increments

We internally decided to avoid previx increments for now.

[H3xept]

Re calldata instead of memory for read-only arguments

Duplicate of #152