Gas Optimizations

[code423n4]

For loop gas optimizations :

In line https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L69, the for loop can be optimized as :

for (uint256 i ; i < weightsLength;) {
            totalWeight += newWeights[i];
            unchecked {
                ++i;
            }
        }

• removing unnecessary initialization
• Using unchecked , as it will not overflow , because there is a check going on.

Such for loop optimizations can be found at below line also :
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/AxelarGateway.sol#L207
Also in line : https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L116
accounts.length - 1 should be pre-calculated, so that the calculation doesn't happen at every loop the for loop runs.

Also in line
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/gas-service/AxelarGasService.sol#L123,
the for loop can be optimized by using ++i instead of i++ and also using unchecked.

Unnecessary initialization to default value:

In line https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L68
uint256 totalWeight = 0; is not required, because totalWeight's default value is 0.
Such other optimizations can be found at :
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

If-else optimizations

In line https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L76,
epochForHash[newOperatorsHash] will always be greater or equal to 0, as it's an uint, so the if statement can be simplified to as :
if (epochForHash[newOperatorsHash]) revert SameOperators();

Similarly in line :
https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/AxelarDepositService.sol#L165
https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/gas-service/AxelarGasService.sol#L128
https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/gas-service/AxelarGasService.sol#L131
https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/AxelarGateway.sol#L255
https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/AxelarGateway.sol#L613
https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/AxelarGateway.sol#L228
https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/ReceiverImplementation.sol#L23
https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/ReceiverImplementation.sol#L51
https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/ReceiverImplementation.sol#L71

<= or >= is cheaper than > or < , so use them if possible:

https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L72
https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/DepositBase.sol#L32
https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L85

[re1ro]

If-else optimizations

Good spot

Rest

Dup #2 #28

[GalloDaSballo]

Less than 300 gas saved