Gas Optimizations

[code423n4]

Hubble contest Gas Optimization

1 use initial value to save gas for uint.

https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/InsuranceFund.sol#L52

uint shares;

2 use cache for array length to save gas.

https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L122
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L130
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L170
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L194
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L263
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L277

3 Delete unused variable. It seems that the following variable will be not used in this construct and other contracts. If it is not used, you can delete it to save gas.

https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L22

4 Avoid extra mstore.

https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/AMM.sol#L121
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/AMM.sol#L141
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/AMM.sol#L614

isNewPosition and isLongPosition are used only one time in

https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/AMM.sol#L123
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/AMM.sol#L143

https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/AMM.sol#L616
You can use position.size == 0 and position.size > 0 directly there to save gas.

if (position.size == 0 || (position.size > 0 ? Side.LONG : Side.SHORT) == side) {
if (position.size > 0) {

5 Use msg.sender instead of _msgSender() to save gas.

https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L65
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L69
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L98
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L113
https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/ClearingHouse.sol#L214

6 Delete unused import statements in AMM.sol

https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/AMM.sol#L5

https://github.com/code-423n4/2022-02-hubble/blob/main/contracts/AMM.sol#L9