➗Gas Saving Technique 12: SafeMath no longer needed

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Introduction

Efficient gas usage in smart contracts is crucial for the cost-effective operation on the Ethereum network. With the release of Solidity 0.8, some previously essential libraries are no longer needed, creating an opportunity for gas savings. One notable example is the SafeMath library, which was commonly used to prevent integer overflow and underflow. Since Solidity 0.8, these checks are built into the compiler, making SafeMath redundant and removable for gas optimization.

Impact & Details

Understanding Gas Consumption

• SafeMath Overhead: Previously, the SafeMath library was indispensable for safely conducting arithmetic operations. However, it introduces additional gas costs due to the external library calls and checks it performs.

• Compiler-Level Checks: Starting with Solidity 0.8, the compiler includes built-in checks for integer overflow and underflow, eliminating the need for SafeMath and thereby saving gas on each transaction that involves arithmetic operations.

How to Remove SafeMath for Gas Savings

Practical Example: Removing SafeMath

Here’s a contract example before and after the removal of SafeMath:

Before Optimization:

solidityCopy code// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;

import "@openzeppelin/contracts/math/SafeMath.sol";

contract MyContract {
    using SafeMath for uint256;

    function add(uint256 a, uint256 b) public pure returns (uint256) {
        return a.add(b);
    }
}

After Optimization:

solidityCopy code// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract MyContract {
    function add(uint256 a, uint256 b) public pure returns (uint256) {
        return a + b;  // Safe due to built-in overflow checks in Solidity 0.8 and above
    }
}

Recommended Mitigation Steps

1. Identify SafeMath Usage: Look through your smart contracts to identify where SafeMath is being used.

2. Remove SafeMath: For contracts using Solidity 0.8 and above, remove SafeMath and refactor arithmetic operations to use standard operators.

3. Test: After removal, rigorously test the contract to ensure it maintains expected functionality while saving gas on arithmetic operations.

Conclusion

Removing the SafeMath library from smart contracts compiled with Solidity 0.8 and above is a straightforward and effective optimization technique for reducing gas consumption. Though the savings per transaction may seem small, it can amount to a substantial total when considering the volume of transactions processed over time. Ensure to comprehensively test the contract post-optimization to validate its behavior and the gas savings achieved.