Partially implement CREATE

Author: sz-piotr

packages/evm/src/Bytes32.ts

@@ -1,5 +1,6 @@
 import BN from 'bn.js'
 import { Byte } from './Byte'
+import { Address } from './Address'
 
 const TWO_POW256 = new BN('1' + '0'.repeat(64), 16)
 const MAX_256 = new BN('f'.repeat(64), 16)
@@ -23,6 +24,10 @@ export class Bytes32 {
     return new Bytes32(new BN(value).toTwos(256))
   }
 
+  static fromAddress (value: Address) {
+    return Bytes32.fromHex(value)
+  }
+
   static fromHex (value: string) {
     return new Bytes32(new BN(value, 16))
   }
@@ -43,6 +48,11 @@ export class Bytes32 {
     return this.value.toString(16, 64)
   }
 
+  toAddress () {
+    const hex = this.toHex()
+    return hex.substring(24) as Address
+  }
+
   toBytes () {
     return this.value.toArray(undefined, 32) as Byte[]
   }

packages/evm/src/opcodes/create.ts

@@ -0,0 +1,54 @@
+import { ExecutionContext } from '../ExecutionContext'
+import { Bytes32 } from '../Bytes32'
+import { getContractAddress } from '../getContractAddress'
+import { executeCode } from '../executeCode'
+
+export function opCREATE (ctx: ExecutionContext) {
+  const value = ctx.stack.pop()
+  const memoryOffset = ctx.stack.pop().toUnsignedNumber()
+  const memoryBytes = ctx.stack.pop().toUnsignedNumber()
+
+  const gasLeft = ctx.message.gasLimit - ctx.gasUsed
+  const gasLimit = allButOne64th(gasLeft)
+  const initCode = ctx.memory.getBytes(memoryOffset, memoryBytes)
+
+  const nonce = ctx.state.getNonce(ctx.message.account)
+  const balance = ctx.state.getBalance(ctx.message.account)
+
+  const contract = getContractAddress(ctx.message.account, nonce)
+
+  if (balance.lt(value)) {
+    ctx.stack.push(Bytes32.ZERO)
+    return
+  }
+
+  ctx.state.setNonce(ctx.message.account, nonce + 1)
+  ctx.state.setBalance(ctx.message.account, balance.sub(value))
+
+  const result = executeCode({
+    account: contract,
+    callDepth: ctx.message.callDepth + 1,
+    sender: ctx.message.account,
+    origin: ctx.message.origin,
+    gasLimit,
+    gasPrice: ctx.message.gasPrice,
+    code: initCode,
+    data: [],
+    enableStateModifications: ctx.message.enableStateModifications,
+    value,
+  }, ctx.state.clone())
+
+  if (result.type === 'ExecutionSuccess') {
+    ctx.stack.push(Bytes32.fromAddress(contract))
+    ctx.state = result.state
+
+    ctx.useGas(result.gasUsed)
+    ctx.refund(result.gasRefund)
+  } else {
+    ctx.stack.push(Bytes32.ZERO)
+  }
+}
+
+function allButOne64th (value: number) {
+  return value - Math.floor(value / 64)
+}

packages/evm/src/opcodes/index.ts

@@ -40,6 +40,7 @@ import { opMSIZE, opMLOAD, opMSTORE, opMSTORE8 } from './memory'
 import { opSSTORE, opSLOAD } from './storage'
 import { Byte } from '../Byte'
 import { opCODESIZE, opCODECOPY } from './code'
+import { opCREATE } from './create'
 
 export { opUnreachable } from './invalid'
 export { makeOpPUSH } from './stack'
@@ -122,6 +123,7 @@ const OP_CODES: Record<number, Opcode | undefined> = {
   0x9d: makeOpSWAP(14),
   0x9e: makeOpSWAP(15),
   0x9f: makeOpSWAP(16),
+  0xf0: opCREATE,
   0xf3: opRETURN,
   0xfd: opREVERT,
 }

packages/evm/test/Bytes32.test.ts

@@ -3,6 +3,7 @@ import { Bytes32 } from '../src/Bytes32'
 import { TestCases } from './opcodes/bytes32/cases'
 import { TestCase } from './opcodes/bytes32/cases/helpers'
 import { Byte } from '../src/Byte'
+import { Address } from '../src/Address'
 
 describe('Bytes32', () => {
   runTestCases('add', TestCases.ADD)
@@ -29,6 +30,21 @@ describe('Bytes32', () => {
   runTestCases('shr', invert(TestCases.SHR))
   runTestCases('sar', invert(TestCases.SAR))
 
+  describe('to and from Address', () => {
+    it('toAddress ignores first bytes', () => {
+      const hex = 'ab'.repeat(16) + 'cd'.repeat(16)
+      const value = Bytes32.fromHex(hex)
+      expect(value.toAddress()).to.equal('ab'.repeat(4) + 'cd'.repeat(16))
+    })
+
+    it('fromAddress works like from hex', () => {
+      const address = 'ab'.repeat(20) as Address
+      const a = Bytes32.fromAddress(address)
+      const b = Bytes32.fromHex(address)
+      expect(a.eq(b)).to.equal(true)
+    })
+  })
+
   describe('to and from number', () => {
     it('fromNumber works for positive numbers', () => {
       const a = Bytes32.fromNumber(42)

packages/evm/test/helpers/executeAssembly.ts

@@ -30,7 +30,10 @@ export function executeAssembly (
 }
 
 export function assemblyToBytecode (code: string): Byte[] {
-  const instructions = code.trim().split(/\s+/)
+  const instructions = code
+    .replace(/\/\/.*/g, ' ') // remove comments
+    .trim()
+    .split(/\s+/)
   const result: Byte[] = []
   for (const instruction of instructions) {
     const opcode = OPCODES[instruction] as Byte

packages/evm/test/opcodes/create.test.ts

@@ -0,0 +1,83 @@
+import { expect } from 'chai'
+import { executeAssembly } from "../helpers"
+import { Address } from "../../src/Address"
+import { State } from "../../src/State"
+import { getContractAddress } from '../../src/getContractAddress'
+import { Bytes32 } from '../../src/Bytes32'
+
+describe('CREATE opcode', () => {
+  const assembly = `
+    PUSH1 05 // size of the code
+    PUSH1 12 // code offset
+    PUSH1 00 // memory offset of the code
+    CODECOPY
+
+    PUSH1 05 // size of the code
+    PUSH1 00 // memory offset of the code
+    PUSH1 69 // value passed
+    CREATE
+
+    PUSH1 00
+    SSTORE // save the address of the created contract
+    STOP
+
+    // code of the contract
+    PUSH1 01
+    PUSH1 00
+    SSTORE // save 1 at address 0 in the storage of the new contract
+  `
+  const account = 'abcd'.repeat(10) as Address
+
+  it('results in the creation of a new contract', () => {
+    const state = new State()
+    state.setNonce(account, 42)
+    state.setBalance(account, Bytes32.fromNumber(0x100))
+
+    const result = executeAssembly(assembly, { account }, state)
+
+    if (result.type !== 'ExecutionSuccess') {
+      expect(result.type).to.equal('ExecutionSuccess')
+    } else {
+      // increments nonce
+      expect(result.state.getNonce(account)).to.equal(43)
+
+      // subtracts balance
+      const balance = result.state.getBalance(account)
+      expect(balance.eq(Bytes32.fromNumber(0x100 - 0x69))).to.equal(true)
+
+      // returns correct address
+      const expectedAddress = getContractAddress(account, 42)
+      const actualAddress = result.state
+        .getStorage(account, Bytes32.ZERO)
+        .toAddress()
+      expect(actualAddress).to.equal(expectedAddress)
+
+      // actually runs the contract code
+      const stored = result.state.getStorage(actualAddress, Bytes32.ZERO)
+      expect(stored.eq(Bytes32.ONE)).to.equal(true)
+    }
+  })
+
+  it('account does not have the balance', () => {
+    const state = new State()
+    state.setNonce(account, 42)
+    state.setBalance(account, Bytes32.fromNumber(0x68))
+
+    const result = executeAssembly(assembly, { account }, state)
+
+    if (result.type !== 'ExecutionSuccess') {
+      expect(result.type).to.equal('ExecutionSuccess')
+    } else {
+      // does not increment the nonce
+      expect(result.state.getNonce(account)).to.equal(42)
+
+      // does not subtract the balance
+      const balance = result.state.getBalance(account)
+      expect(balance.eq(Bytes32.fromNumber(0x68))).to.equal(true)
+
+      // returns zero
+      const returnValue = result.state.getStorage(account, Bytes32.ZERO)
+      expect(returnValue).to.equal(Bytes32.ZERO)
+    }
+  })
+})