QuickSwap and StellaSwap contest - Tomio's results

Title: Gas savings for using solidity 0.8.10

Proof of Concept: All contract in scope

Recommended Mitigation Steps: Consider to upgrade pragma to at least 0.8.10.

Solidity 0.8.10 has a useful change which reduced gas costs of external calls Reference: here

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Title: Unchecking arithmetics operations that can't underflow/overflow

Proof of Concept: TokenDeltaMath.sol#L52 Should be unchecked due to L#51

Recommended Mitigation Steps: Use unchecked

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Title: Using != in require statement is more gas efficient

Proof of Concept: PriceMovementMath.sol#L52-L53 AlgebraPool.sol#L434 AlgebraPool.sol#L469

Recommended Mitigation Steps: Change > 0 to != 0

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Title: >= is cheaper than >

Impact: Strict inequalities (>) are more expensive than non-strict ones (>=). This is due to some supplementary checks (ISZERO, 3 gas)

Proof of Concept: AlgebraPool.sol#L237

Recommended Mitigation Steps: Consider using >= instead of > to avoid some opcodes

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Title: Default value initialization

Impact: If a variable is not set/initialized, it is assumed to have the default value (0, false, 0x0 etc depending on the data type). Explicitly initializing it with its default value is an anti-pattern and wastes gas.

Proof of Concept: DataStorage.sol#L307

Recommended Mitigation Steps: Remove explicit initialization for default values.

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Title: Caching length for loop can save gas

Proof of Concept: DataStorage.sol#L307

Recommended Mitigation Steps: Change to:

    uint256 Length = secondsAgos.length;
    for (uint256 i = 0; i < Length; i++) {

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Title: Using unchecked and prefix increment is more effective for gas saving:

Proof of Concept: DataStorage.sol#L307

Recommended Mitigation Steps: Change to:

for (uint256 i = 0; i < secondsAgos.length;) {
// ...
unchecked { ++i; }
}

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Title: Using multiple require instead && can save gas

Proof of Concept: DataStorageOperator.sol#L46 AlgebraPool.sol#L739 AlgebraPool.sol#L743

Recommended Mitigation Steps: Change to:

	require(_feeConfig.gamma1 != 0, 'Gammas must be > 0');
	require(_feeConfig.gamma2 != 0, 'Gammas must be > 0');
	require(_feeConfig.volumeGamma != 0, 'Gammas must be > 0');

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Title: abi.encode() is less efficient than abi.encodePacked()

Proof of Concept: AlgebraPoolDeployer.sol#L51

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Title: Set as immutable can save gas

Proof of Concept: AlgebraPoolDeployer.sol#L19

Recommended Mitigation Steps: can be set as immutable, which already set once in the constructor

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