Hardfork.hasEIP3855

Check if PUSH0 opcode is available

Try it Live

Run Hardfork examples in the interactive playground

EIP-3855 Features

Active Since: Shanghai (April 12, 2023)

PUSH0 Opcode

Opcode: 0x5F

Function: Pushes constant 0 onto the stack

Gas Cost: 2 gas

Benefits

Gas Savings:

• PUSH0: 2 gas
• PUSH1 0x00: 3 gas
• Saves 1 gas per zero push (33% reduction)

Bytecode Size:

• PUSH0: 1 byte
• PUSH1 0x00: 2 bytes
• Reduces contract size by 1 byte per occurrence

Common Use Cases:

• Function return values initialization
• Array/mapping default values
• Stack manipulation
• Placeholder values

Usage Patterns

Opcode Selection

Select optimal zero-push implementation:

import { Hardfork } from 'tevm'

function getPushZeroOpcode(fork: BrandedHardfork) {
  if (fork.hasEIP3855()) {
    return {
      opcode: 0x5F,        // PUSH0
      gas: 2,
      bytes: [0x5F]
    }
  }

  return {
    opcode: 0x60,          // PUSH1
    gas: 3,
    bytes: [0x60, 0x00]
  }
}

Compiler Optimization

Enable PUSH0 in compiler:

import { Hardfork } from 'tevm'

function getCompilerTarget(fork: BrandedHardfork) {
  return {
    hardfork: Hardfork.toString(fork),
    usePUSH0: fork.hasEIP3855()
  }
}

Bytecode Generation

Generate optimal bytecode:

import { Hardfork } from 'tevm'

function emitPushZero(fork: BrandedHardfork): Uint8Array {
  if (fork.hasEIP3855()) {
    return new Uint8Array([0x5F])  // PUSH0
  }

  return new Uint8Array([0x60, 0x00])  // PUSH1 0x00
}

Gas Estimation

Calculate gas costs:

import { Hardfork } from 'tevm'

function estimatePushZeroGas(
  fork: BrandedHardfork,
  occurrences: number
): number {
  if (fork.hasEIP3855()) {
    return 2 * occurrences  // PUSH0: 2 gas each
  }

  return 3 * occurrences  // PUSH1 0x00: 3 gas each
}

// Typical contract might save 100-500 gas
const savings = estimatePushZeroGas(MERGE, 100) - estimatePushZeroGas(SHANGHAI, 100)
console.log(`Gas savings: ${savings}`)  // 100 gas

Network Configuration

Validate PUSH0 support:

import { Hardfork, SHANGHAI } from 'tevm'

function validatePUSH0Support(config: NetworkConfig) {
  const fork = Hardfork(config.hardfork)

  if (fork.hasEIP3855()) {
    console.log("PUSH0 optimization available")
  } else {
    console.log("PUSH0 not available, using PUSH1 0x00")
  }
}

Compiler Integration

Solidity compiler support:

import { Hardfork } from 'tevm'

function getSoliditySettings(fork: BrandedHardfork) {
  return {
    evmVersion: fork.hasEIP3855() ? "shanghai" : "paris",
    optimizer: {
      enabled: true,
      runs: 200
    }
  }
}

EIP References

Primary:

• EIP-3855 - PUSH0 instruction

Impact

For Developers:

• Smaller contract sizes (reduces deployment costs)
• Lower execution costs (1 gas saved per zero push)
• Must target Shanghai or later for PUSH0 optimization

For Compilers:

• Can optimize PUSH1 0x00 → PUSH0 when targeting Shanghai+
• Reduces bytecode size without semantic changes

For Contracts:

• Typical savings: 50-500 gas per transaction
• Reduced deployment costs: 100-1000 gas per contract
• Zero runtime overhead

See Also

• hasEIP1559 - Check EIP-1559 base fee availability (London)
• hasEIP4844 - Check blob transactions availability (Cancun)
• isAtLeast - General version comparison