How to implement EVM using Golang

With the continuous development of blockchain technology, Ethereum, as the most representative smart contract platform, already has good support and a huge ecosystem for developers. However, since the software architecture of the Ethereum Virtual Machine (EVM) is based on the development of the Solidity language, in addition, in order to improve performance, the EVM implements a JIT (Just In Time) compiler for code optimization, all of which are done in a certain way. To this extent, it limits the development efficiency of the Ethereum ecosystem.

Based on these problems, many developers try to use other programming languages ​​​​to develop EVM in the hope of achieving more efficient smart contract code execution. Golang is a programming language developed by Google that provides a very convenient way to do low-level programming. Below we will explore how to use Golang to implement EVM.

EVM Overview

The Ethereum Virtual Machine (EVM) is a stack-based virtual machine that executes Ethereum smart contracts. EVM provides a unified execution environment on the entire Ethereum network, ensuring that smart contracts can run as expected on different nodes. The EVM defines a set of instructions that change state during specific operations. These states include memory, storage, and stack.

Use Golang to implement EVM

To use Golang to implement EVM, we need to install go-ethereum first. go-ethereum is an official Golang implementation of Ethereum that provides some very useful libraries and features. It can be used as an Ethereum node for building Ethereum dApps (decentralized applications).

Assuming we have installed the go-ethereum and solidity compilers, we can start implementing EVM using the following steps:

Step 1: Define the instruction set of EVM

In Golang , we can use enumeration types to define the instruction set of the EVM, for example:

type OpCode byte

const (
  STOP OpCode = iota
  ADD
  MUL
  SUB
  DIV
  SDIV
  MOD
  SMOD
  ADDMOD
  MULMOD
  EXP
  SIGNEXTEND
  ...
)

These instructions can be found in the Ethereum Yellow Book, or obtained from the source code in the go-ethereum package. We need to define a method for each instruction that executes the logic of the instruction. For example, for the ADD instruction, we can define the following method:

func (evm *EVM) add() {
  x, y := evm.stack.Pop(), evm.stack.Pop()
  result := x.Add(y)
  evm.stack.Push(result)
}

Step 2: Parse Solidity bytecode

When we write a smart contract using Solidity, the compiler compiles it into bytes code form and then deploy it on the Ethereum network. In our Golang EVM, we need to first parse the Solidity bytecode and then convert it into EVM instructions. We can do this using the parser from the go-ethereum package. For example:

import (
  "github.com/ethereum/go-ethereum/common"
  "github.com/ethereum/go-ethereum/core/vm"
)

func (evm *EVM) execute(code []byte) {
  vm := vm.NewEVM(evm.context, evm.stateDB, evm.vmConfig)
  contract := vm.NewContract(&vm.ContractConfig{
    Code:      common.CopyBytes(code),
    GasLimit:  1000000,
    Value:     big.NewInt(0),
  })
  contract.SetCallCodeFn(evm.callCode)
  contract.SetStaticCallFn(evm.staticCall)
  contract.SetDelegateCallFn(evm.delegateCall)
  vm.Execute(evm.context, contract)
}

The above code will parse the Solidity bytecode into a Contract object, and then call the EVM's Execute() method to execute the code.

Step 3: Implement memory, storage and stack

EVM has three states: memory, storage and stack. In Golang EVM, we need to implement these states. We can use Golang's slice as memory, map as storage, and Golang's stack as stack.

type EVM struct {
  context  *core.ExecutionContext
  stateDB  *state.StateDB
  vmConfig vm.Config

  memory []byte
  storage map[common.Hash] common.Hash
  stack *stack
}

Step 4: Implement the logic of the instruction set

After we define the instruction set, we need to implement the logic of each instruction. Each instruction changes the state of the stack. For example, in the case of the ADD instruction, it pops two values ​​from the stack, adds them, and finally pushes the result back onto the stack. We can define the following method to implement the logic of the ADD instruction:

func (evm *EVM) add() {
  x, y := evm.stack.Pop(), evm.stack.Pop()
  result := x.Add(y)
  evm.stack.Push(result)
}

Step 5: Implement various exception handling

When implementing the logic of the instruction, we need to handle various exceptions, such as Stack overflow, call depth is too large, memory overflow, etc. Assuming that our Golang EVM is a complete Ethereum implementation, we need to handle a series of other exceptions, such as the account does not exist, the account is locked, mining has not been completed, etc.

Conclusion

Using Golang to implement EVM can improve the performance and development efficiency of smart contracts. It provides developers with greater flexibility and freedom to better adapt to various application scenarios. Although the implementation of Golang EVM will be more complicated than the implementation of Solidity EVM, it provides a new and efficient path for the development of EVM.

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