Ethereum Virtual Machine (EVM) Control Flow Instructions

Table of Contents

Introduction
Module Contents
- Functions
Module Details
- stop
- jump
- jumpi
- pc
- gas_left
- jumpdest

Introduction

Implementations of the EVM control flow instructions.

Module Contents

Functions

`stop`	Stop further execution of EVM code.
`jump`	Alter the program counter to the location specified by the top of the
`jumpi`	Alter the program counter to the specified location if and only if a
`pc`	Push onto the stack the value of the program counter after reaching the
`gas_left`	Push the amount of available gas (including the corresponding reduction
`jumpdest`	Mark a valid destination for jumps. This is a noop, present only

Module Details

stop

stop(evm: ethereum.london.vm.Evm) → None

Stop further execution of EVM code.

Parameters: evm – The current EVM frame.

def stop(evm: Evm) -> None:
    # STACK
    pass

    # GAS
    pass

    # OPERATION
    evm.running = False

    # PROGRAM COUNTER
    evm.pc += 1

jump

jump(evm: ethereum.london.vm.Evm) → None

Alter the program counter to the location specified by the top of the stack.

Parameters: evm – The current EVM frame.

def jump(evm: Evm) -> None:
    # STACK
    jump_dest = Uint(pop(evm.stack))

    # GAS
    charge_gas(evm, GAS_MID)

    # OPERATION
    if jump_dest not in evm.valid_jump_destinations:
        raise InvalidJumpDestError

    # PROGRAM COUNTER
    evm.pc = Uint(jump_dest)

jumpi

jumpi(evm: ethereum.london.vm.Evm) → None

Alter the program counter to the specified location if and only if a condition is true. If the condition is not true, then the program counter would increase only by 1.

Parameters: evm – The current EVM frame.

def jumpi(evm: Evm) -> None:
    # STACK
    jump_dest = Uint(pop(evm.stack))
    conditional_value = pop(evm.stack)

    # GAS
    charge_gas(evm, GAS_HIGH)

    # OPERATION
    if conditional_value == 0:
        destination = evm.pc + 1
    elif jump_dest not in evm.valid_jump_destinations:
        raise InvalidJumpDestError
    else:
        destination = jump_dest

    # PROGRAM COUNTER
    evm.pc = Uint(destination)

pc

pc(evm: ethereum.london.vm.Evm) → None

Push onto the stack the value of the program counter after reaching the current instruction and without increasing it for the next instruction.

Parameters: evm – The current EVM frame.

def pc(evm: Evm) -> None:
    # STACK
    pass

    # GAS
    charge_gas(evm, GAS_BASE)

    # OPERATION
    push(evm.stack, U256(evm.pc))

    # PROGRAM COUNTER
    evm.pc += 1

gas_left

gas_left(evm: ethereum.london.vm.Evm) → None

Push the amount of available gas (including the corresponding reduction for the cost of this instruction) onto the stack.

Parameters: evm – The current EVM frame.

def gas_left(evm: Evm) -> None:
    # STACK
    pass

    # GAS
    charge_gas(evm, GAS_BASE)

    # OPERATION
    push(evm.stack, U256(evm.gas_left))

    # PROGRAM COUNTER
    evm.pc += 1

jumpdest

jumpdest(evm: ethereum.london.vm.Evm) → None

Mark a valid destination for jumps. This is a noop, present only to be used by JUMP and JUMPI opcodes to verify that their jump is valid.

Parameters: evm – The current EVM frame.

def jumpdest(evm: Evm) -> None:
    # STACK
    pass

    # GAS
    charge_gas(evm, GAS_JUMPDEST)

    # OPERATION
    pass

    # PROGRAM COUNTER
    evm.pc += 1