Gas Optimizations

[code423n4]

1. !=0 more effective than < 0

Proof of Concept:
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L229
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L385
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L1078

Recommended Mitigation Steps:
Change > 0 or < 0 to != 0

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2. Can save gas by using -- instead of - 1

Proof of Concept:
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L515

Recommended Mitigation Steps:
Change to:

 uint256 high = --nbCheckpoints;

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3. unnecessary value set. the default value of uint is zero.

Proof of Concept:
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L516
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L796
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L807

Recommended Mitigation Steps:
remove 0

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4. unnecessary value set. the default value of bool is false

Proof of Concept:
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L103

Recommended Mitigation Steps:
remove false

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5. more efficient gas usage by removing && operator

oof of Concept:
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L1271

Recommended Mitigation Steps:

require(user != address(0)):
require(kicker != address(0), "hPAL: Address Zero");

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6. Using > is cheaper than >=

Proof of Concept:
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L1194-L1195
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L1141-L1143

Recommended Mitigation Steps:
Change from >= to >

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7. the best way to use SafeERC20.function for gas opt

Proof of Concept:
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/PaladinRewardReserve.sol#L12

Recommended Mitigation Steps:
by not declaring:

using SafeERC20 for IERC20;

and use:

SafeERC20.safeTransfer(IERC20(token), receiver, amount);

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8. Using calldata to store struct data type can save gas

Proof of Concept:
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L451
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L466
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L482
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/HolyPaladinToken.sol#L492

Recommended Mitigation Steps:
Change from memory to calldata

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9. caching proof.length for loop can save gas

Proof of Concept:
https://github.com/code-423n4/2022-03-paladin/blob/main/contracts/open-zeppelin/utils/MerkleProof.sol#L28

Recommended Mitigation Steps:

uint256 saveLengt = proof.length
for (uint256 i; i < saveLengt; ++i)

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[Kogaroshi]

QA & gas optimizations changes are done in the PR: PaladinFinance/Paladin-Tokenomics#6
(some changes/tips were implemented, others are noted but won't be applied)