zksolc produces x5 larger bytecode size compare to solc

[Khang-NT]

🐛 Bug Report for hardaht-zksync plugins

💥 Plugin name

hardaht-zksync-solc

📝 Description

Hardhat config:

const config: HardhatUserConfig = {
    solidity: {
        version: "0.8.25",
        settings: {
            viaIR: true,
            evmVersion: "cancun",
            optimizer: {
                enabled: true,
                runs: 2000
            },
        },
    },
    zksolc: {
        version: "1.4.1", // Uses latest available in https://github.com/matter-labs/zksolc-bin/
        settings: {
            optimizer: {
                enabled: true,
                mode: 'z' // even worse if mode = 3
            },
            contractsToCompile: ["USDC.sol", "MyContract.sol"]
        }
    },
    networks: {
        hardhat: {
            zksync: process.env.ZKSYNC_NODE === "1",
        },
    },
};

🔄 Reproduction Steps

$ ZKSYNC_NODE=0 hardhat compile
·------------------------|--------------------------------|--------------------------------·
|  Solc version: 0.8.25  ·  Optimizer enabled: true       ·  Runs: 2000                    │
·························|································|·································
|  Contract Name         ·  Deployed size (KiB) (change)  ·  Initcode size (KiB) (change)  │
·························|································|·································
·························|································|·································
|  USDC                  ·                 2.038 (0.000)  ·                 2.906 (0.000)  │
·························|································|·································
|  MyContract            ·                 9.904 (0.000)  ·                10.780 (0.000)  │
·------------------------|--------------------------------|--------------------------------·

$ ZKSYNC_NODE=1 hardhat compile
Compiling contracts for zkSync Era with zksolc v1.4.1 and solc v0.8.25
Compiling 11 Solidity files
Generating typings for: 13 artifacts in dir: typechain for target: ethers-v6
Successfully generated 50 typings!
Successfully compiled 11 Solidity files
 ·------------------------|--------------------------------|--------------------------------·
|  Solc version: 0.8.25  ·  Optimizer enabled: true       ·  Runs: undefined               │
·························|································|·································
|  Contract Name         ·  Deployed size (KiB) (change)  ·  Initcode size (KiB) (change)  │
·························|································|·································
·························|································|·································
|  USDC                  ·                      6.094 ()  ·                      6.094 ()  │
·························|································|·································
|  MyContract            ·                     31.531 ()  ·                     31.531 ()  │
·------------------------|--------------------------------|--------------------------------·

Set optimizer.mode = "3" and run again:

$ ZKSYNC_NODE=1 hardhat compile
Compiling contracts for zkSync Era with zksolc v1.4.1 and solc v0.8.25
Compiling 11 Solidity files
Generating typings for: 13 artifacts in dir: typechain for target: ethers-v6
Successfully generated 50 typings!
Successfully compiled 11 Solidity files
 ·------------------------|--------------------------------|--------------------------------·
|  Solc version: 0.8.25  ·  Optimizer enabled: true       ·  Runs: undefined               │
·························|································|·································
|  Contract Name         ·  Deployed size (KiB) (change)  ·  Initcode size (KiB) (change)  │
·························|································|·································
·························|································|·································
|  USDC                  ·                8.219 (+2.125)  ·                8.219 (+2.125)  │
·························|································|·································
|  MyContract            ·              56.406 (+24.875)  ·              56.406 (+24.875)  │
·------------------------|--------------------------------|--------------------------------·

zksolc produces insane large bytecode size, x3 times solc produces when using optimizer.mode = 'z', and x5 when using optimizer.mode = "3"

Here's USDC.sol, just a simple ERC20 contract:

pragma solidity ^0.8.20;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";

contract USDC is ERC20 {
    constructor() ERC20("Fake USDC", "USDC") {
        _mint(msg.sender, 1000000 * (10 ** uint256(decimals())));
    }

    function decimals() public pure override returns (uint8) {
        return 10;
    }
}

🖥️ Environment

• Node version: [e.g., Node 18.18.2]

[hedgar2017]

Thanks for the report, but it is not a bug.

EraVM bytecode is larger than that of EVM, mostly due to different encoding and the usage of System Contracts which make EraVM behavior equivalent to EVM's.