Paladin contest - saian's results

Gas Optimization

Initializing with default values

When a variable is created it is initialized with default values, explicitly initializing it wasted gas

Proof of concept

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L103

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L516

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L688

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L807

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L945

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L977

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L1009

!= is more efficient than > for unsigned integers

!= consumes less gas than > in require statements with optimizer enabled

Proof of concept

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L229

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L385

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L1062

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L1078

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L1237-1249

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L1272

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L1342

Storage value can be cached to save gas

Repeated storage reads in a block can be cached in a temporary variable to save gas

Proof of concept

userLocks[msg.sender].length in https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L270-L272

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L286-L287

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L348-L350

claimableRewards[msg.sender] in https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L388

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L455-L456

Storage read in if statements in while loop

https://github.com/code-423n4/2022-03-paladin/blob/ 9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L520-L523

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L692-L695

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L947-L957

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L979-L989

balanceOf in https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L558-L572

currentDropPerSecond in https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L736

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L809-L814

currentTotalLocked in https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L1165-1169

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L1222-1231

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L1251-1267

Add unchecked to save gas

Adding unchecked to expressions that wont underflow/overflow can avoid default underflow/overflow checks and save gas

Proof of concept

claimAmount will be less than or equal to claimRewards

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L392

Mitigation

unchecked can be added to the statement

Statement can be replaced by immutable

In HolyPaladinToken:_updateDropPerSecond dropDecreasePerMonth calculation uses constant and immutable values and after dropDecreaseDuration only if block is executed, so dropDecreasePerMonth can be changed to immutable

Proof of concept

https://github.com/code-423n4/2022-03-paladin/blob/9c26ec8556298fb1dc3cf71f471aadad3a5c74a0/contracts/HolyPaladinToken.sol#L729

Mitigation

dropDecreaseDuration can be change to immutable and set in constructor