Bytecode

O bytecode é uma forma de instrução executável por um computador ou uma máquina virtual. No contexto do Ethereum e da Ethereum Virtual Machine (EVM), o bytecode refere-se ao código de baixo nível que a EVM pode interpretar e executar diretamente. Esse bytecode é gerado a partir do código-fonte de um contrato inteligente escrito em uma linguagem de alto nível, como Solidity ou Vyper, por meio de um processo de compilação.

Características do Bytecode no Ethereum

• Compilado a partir de código de alto nível: Os desenvolvedores escrevem contratos inteligentes em linguagens de alto nível projetadas especificamente para o Ethereum, como Solidity. Esses contratos são então compilados em bytecode para que possam ser implantados e executados na EVM.

• Executável pela EVM: A EVM foi projetada para executar bytecode. Cada nó da rede Ethereum possui uma instância da EVM, permitindo que contratos inteligentes sejam executados de forma descentralizada em toda a rede.

• Determinístico: O bytecode executado na EVM produz resultados determinísticos. Isso significa que, dadas as mesmas entradas e o mesmo estado da blockchain, a execução do bytecode sempre produzirá os mesmos resultados. Essa característica é crucial para o consenso e a integridade da rede Ethereum.

• Consumo de gas: A execução de operações no bytecode consome "gas", que é uma medida do poder computacional necessário. Cada operação no bytecode tem um custo de gas associado, e os usuários devem pagar esse gas para executar operações e alterar o estado da blockchain.

Processo de compilação

O processo de compilação transforma o código-fonte do contrato inteligente em bytecode. Esse processo geralmente também gera um ABI, que define como chamar as funções do contrato, mas o bytecode é o código que realmente é executado na blockchain.

Imagine que você tenha um contrato inteligente simples escrito em Solidity que armazena uma mensagem. A versão em Solidity pode ser assim:

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

contract SimpleStorage {

    string public message;

    constructor(string memory initialMessage) {
        message = initialMessage;
    }

    function setMessage(string memory newMessage) public {
        message = newMessage;
    }

    function getMessage() public view returns (string memory) {
        return message;
    }
}

Uma vez compilado, esse contrato é transformado em bytecode, que é uma sequência de bytes que representa as instruções que a EVM executará. O bytecode para este contrato é a longa sequência de caracteres hexadecimais mostrada abaixo. Embora difícil de ler ou interpretar por humanos, a EVM pode executar esse código de maneira eficiente.

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