minimal node.js script for benchmarking ewasm contracts/precompiles

ewasm-bencher.js

// node --experimental-wasm-bigint ewasm-bencher.js bn128mul_metered.wasm "039730ea8dff1254c0fee9c0ea777d29a9c710b7e616683f194f18c43b43b869073a5ffcc6fc7a28c30723d6e58ce577356982d65b833a5a5c15bf9024b43d98ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff" "00a1a234d08efaa2616607e31eca1980128b00b415c845ff25bba3afcb81dc00242077290ed33906aeb8e42fd98c41bcb9057ba03421af3f2d08cfc441186024"

var args = process.argv.slice(2);
var wasmfile = args[0];
var input = args[1];
var expected = args[2];

if (args.length < 3) {
  console.log('missing an arg!');
  process.exit(1);
}

const readAsBinary = filename => {
if (typeof process === 'object' && typeof require === 'function') {
    const binary = require('fs').readFileSync(filename);
    return !binary.buffer ? new Uint8Array(binary) : binary;
} else
    return typeof readbuffer === 'function'
        ? new Uint8Array(readbuffer(filename))
        : read(filename, 'binary');
};

const wasmBytes = readAsBinary(wasmfile)

let totalGasUsed = BigInt(0);
let useGasCalls = 0;
let exported_mem;

const inputBytes = new Uint8Array(Math.ceil(input.length / 2));

function getCallDataSize() {
  return inputBytes.length;
}

function useGas(a) {
  totalGasUsed = totalGasUsed + a;
  useGasCalls = useGasCalls + 1;
}

function callDataCopy(resultOffset, dataOffset, length) {
  for (var i = 0; i < inputBytes.length; i++) inputBytes[i] = parseInt(inputHex.substr(i * 2, 2), 16);
  const asBytes = new Uint8Array(exported_mem.buffer, resultOffset, length+1);
  asBytes.set(inputBytes);
}

function revert (dataOffset, dataLength) {
  console.log('revert dataOffset, dataLength', dataOffset, dataLength)
}

function finish (dataOffset, dataLength) {
  const returnBytes = new Uint8Array(exported_mem.buffer, dataOffset, dataLength);

  let convertedBack = '';
  for (var i = 0; i < dataLength; i++) {
    if (returnBytes[i] < 16) convertedBack += '0';
    convertedBack += returnBytes[i].toString(16);
  }

  if (convertedBack == expected) {
    throw "finished normally!";
  } else {
    console.error('Expected: ' + expected + '   got: '  + convertedBack);
    throw "incorrect return val!"
  }
}


const imports = {
    ethereum: {
        'getCallDataSize': getCallDataSize,
        'useGas': useGas,
        'callDataCopy': callDataCopy,
        'finish': finish,
        'revert': revert
    },
    env: {}
};

imports.env.memory = new WebAssembly.Memory({ initial: 10 })

console.time('instantiate');
WebAssembly.instantiate(wasmBytes, imports)
  .then(r => {
    exported_mem = r.instance.exports.memory;
    console.timeEnd('instantiate');
    console.time('exec');
    try {
      r.instance.exports.main();
      console.timeEnd('exec');
    } catch (e) {
      console.timeEnd('exec');
      if (e == "finished normally!") {
        console.log('gas used:', totalGasUsed);
        console.log('useGas calls:', useGasCalls);
      } else {
        console.log('caught error:', e)
      }
    }
  });