How to perform gas optimization in Hardhat?

Gas optimization in Hardhat is an important part of smart contract development. Here are the main optimization strategies:

1. Use Gas Reporter Plugin

Install and configure gas-reporter:

bash
npm install --save-dev hardhat-gas-reporter

Configure in hardhat.config.js:

javascript
require("hardhat-gas-reporter");

module.exports = {
  gasReporter: {
    enabled: true,
    currency: "USD",
    gasPrice: 20
  }
};

Run tests to view gas usage:

bash
npx hardhat test --gas

2. Solidity Compiler Optimization

Enable compiler optimization:

javascript
solidity: {
  version: "0.8.19",
  settings: {
    optimizer: {
      enabled: true,
      runs: 200  // Adjust based on contract call frequency
    }
  }
}

3. Contract Code Optimization Techniques

• Use uint256 instead of smaller types: EVM operates most efficiently with 32 bytes
• Batch operations: Reduce loops and multiple calls
• Use events instead of storage: Events are cheaper than storage
• Use calldata instead of memory: For read-only parameters
• Short-circuit evaluation: Check most likely true conditions first in if statements

4. Storage Optimization

• Pack variables: Pack small type variables into the same slot
• Use mapping instead of array: For sparse data
• Delete unnecessary storage: Use delete keyword

5. Test Gas Usage

Verify gas consumption in tests:

javascript
it("should use reasonable gas", async function () {
  const tx = await contract.someFunction();
  const receipt = await tx.wait();
  console.log("Gas used:", receipt.gasUsed.toString());
  
  // Assert gas usage is within reasonable range
  expect(receipt.gasUsed).to.be.below(100000);
});

6. Use Hardhat Console to Test Gas

bash
npx hardhat console

javascript
const tx = await contract.someFunction();
const receipt = await tx.wait();
console.log("Gas used:", receipt.gasUsed.toString());

Best Practices:

• Continuously monitor gas usage during development
• Optimize gas for critical functions
• Regularly check with gas-reporter
• Verify gas consumption on testnets
• Consider the impact of gas price fluctuations on user experience