core/vm: improved EVM run loop & instruction calling (#3378)

The run loop, which previously contained custom opcode executes have been
removed and has been simplified to a few checks.

Each operation consists of 4 elements: execution function, gas cost function,
stack validation function and memory size function. The execution function
implements the operation's runtime behaviour, the gas cost function implements
the operation gas costs function and greatly depends on the memory and stack,
the stack validation function validates the stack and makes sure that enough
items can be popped off and pushed on and the memory size function calculates
the memory required for the operation and returns it.

This commit also allows the EVM to go unmetered. This is helpful for offline
operations such as contract calls.

1 files changed, 92 insertions, 79 deletions

diff --git a/core/vm/environment.go b/core/vm/environment.go
index 50a09d444..b74b3a795 100644
--- a/core/vm/environment.go
+++ b/core/vm/environment.go
@@ -19,6 +19,7 @@ package vm
 import (
 	"fmt"
 	"math/big"
+	"sync/atomic"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
@@ -55,41 +56,54 @@ type Context struct {
 	Difficulty  *big.Int       // Provides information for DIFFICULTY
 }
 
-// Environment provides information about external sources for the EVM
+// EVM provides information about external sources for the EVM
 //
-// The Environment should never be reused and is not thread safe.
-type Environment struct {
+// The EVM should never be reused and is not thread safe.
+type EVM struct {
 	// Context provides auxiliary blockchain related information
 	Context
 	// StateDB gives access to the underlying state
 	StateDB StateDB
 	// Depth is the current call stack
-	Depth int
+	depth int
 
-	// evm is the ethereum virtual machine
-	evm Vm
 	// chainConfig contains information about the current chain
 	chainConfig *params.ChainConfig
-	vmConfig    Config
+	// virtual machine configuration options used to initialise the
+	// evm.
+	vmConfig Config
+	// global (to this context) ethereum virtual machine
+	// used throughout the execution of the tx.
+	interpreter *Interpreter
+	// abort is used to abort the EVM calling operations
+	// NOTE: must be set atomically
+	abort int32
 }
 
-// NewEnvironment retutrns a new EVM environment.
-func NewEnvironment(context Context, statedb StateDB, chainConfig *params.ChainConfig, vmConfig Config) *Environment {
-	env := &Environment{
-		Context:     context,
+// NewEVM retutrns a new EVM evmironment.
+func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig, vmConfig Config) *EVM {
+	evm := &EVM{
+		Context:     ctx,
 		StateDB:     statedb,
 		vmConfig:    vmConfig,
 		chainConfig: chainConfig,
 	}
-	env.evm = New(env, vmConfig)
-	return env
+
+	evm.interpreter = NewInterpreter(evm, vmConfig)
+	return evm
+}
+
+// Cancel cancels any running EVM operation. This may be called concurrently and it's safe to be
+// called multiple times.
+func (evm *EVM) Cancel() {
+	atomic.StoreInt32(&evm.abort, 1)
 }
 
 // Call executes the contract associated with the addr with the given input as paramaters. It also handles any
 // necessary value transfer required and takes the necessary steps to create accounts and reverses the state in
 // case of an execution error or failed value transfer.
-func (env *Environment) Call(caller ContractRef, addr common.Address, input []byte, gas, value *big.Int) ([]byte, error) {
-	if env.vmConfig.NoRecursion && env.Depth > 0 {
+func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas, value *big.Int) (ret []byte, err error) {
+	if evm.vmConfig.NoRecursion && evm.depth > 0 {
 		caller.ReturnGas(gas)
 
 		return nil, nil
@@ -97,48 +111,48 @@ func (env *Environment) Call(caller ContractRef, addr common.Address, input []by
 
 	// Depth check execution. Fail if we're trying to execute above the
 	// limit.
-	if env.Depth > int(params.CallCreateDepth.Int64()) {
+	if evm.depth > int(params.CallCreateDepth.Int64()) {
 		caller.ReturnGas(gas)
 
-		return nil, DepthError
+		return nil, ErrDepth
 	}
-	if !env.Context.CanTransfer(env.StateDB, caller.Address(), value) {
+	if !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) {
 		caller.ReturnGas(gas)
 
 		return nil, ErrInsufficientBalance
 	}
 
 	var (
-		to                  Account
-		snapshotPreTransfer = env.StateDB.Snapshot()
+		to       Account
+		snapshot = evm.StateDB.Snapshot()
 	)
-	if !env.StateDB.Exist(addr) {
-		if Precompiled[addr.Str()] == nil && env.ChainConfig().IsEIP158(env.BlockNumber) && value.BitLen() == 0 {
+	if !evm.StateDB.Exist(addr) {
+		if PrecompiledContracts[addr] == nil && evm.ChainConfig().IsEIP158(evm.BlockNumber) && value.BitLen() == 0 {
 			caller.ReturnGas(gas)
 			return nil, nil
 		}
 
-		to = env.StateDB.CreateAccount(addr)
+		to = evm.StateDB.CreateAccount(addr)
 	} else {
-		to = env.StateDB.GetAccount(addr)
+		to = evm.StateDB.GetAccount(addr)
 	}
-	env.Transfer(env.StateDB, caller.Address(), to.Address(), value)
+	evm.Transfer(evm.StateDB, caller.Address(), to.Address(), value)
 
 	// initialise a new contract and set the code that is to be used by the
-	// E The contract is a scoped environment for this execution context
+	// E The contract is a scoped evmironment for this execution context
 	// only.
 	contract := NewContract(caller, to, value, gas)
-	contract.SetCallCode(&addr, env.StateDB.GetCodeHash(addr), env.StateDB.GetCode(addr))
+	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
 	defer contract.Finalise()
 
-	ret, err := env.EVM().Run(contract, input)
+	ret, err = evm.interpreter.Run(contract, input)
 	// When an error was returned by the EVM or when setting the creation code
 	// above we revert to the snapshot and consume any gas remaining. Additionally
 	// when we're in homestead this also counts for code storage gas errors.
 	if err != nil {
 		contract.UseGas(contract.Gas)
 
-		env.StateDB.RevertToSnapshot(snapshotPreTransfer)
+		evm.StateDB.RevertToSnapshot(snapshot)
 	}
 	return ret, err
 }
@@ -148,8 +162,8 @@ func (env *Environment) Call(caller ContractRef, addr common.Address, input []by
 // case of an execution error or failed value transfer.
 //
 // CallCode differs from Call in the sense that it executes the given address' code with the caller as context.
-func (env *Environment) CallCode(caller ContractRef, addr common.Address, input []byte, gas, value *big.Int) ([]byte, error) {
-	if env.vmConfig.NoRecursion && env.Depth > 0 {
+func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte, gas, value *big.Int) (ret []byte, err error) {
+	if evm.vmConfig.NoRecursion && evm.depth > 0 {
 		caller.ReturnGas(gas)
 
 		return nil, nil
@@ -157,33 +171,33 @@ func (env *Environment) CallCode(caller ContractRef, addr common.Address, input
 
 	// Depth check execution. Fail if we're trying to execute above the
 	// limit.
-	if env.Depth > int(params.CallCreateDepth.Int64()) {
+	if evm.depth > int(params.CallCreateDepth.Int64()) {
 		caller.ReturnGas(gas)
 
-		return nil, DepthError
+		return nil, ErrDepth
 	}
-	if !env.CanTransfer(env.StateDB, caller.Address(), value) {
+	if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
 		caller.ReturnGas(gas)
 
-		return nil, fmt.Errorf("insufficient funds to transfer value. Req %v, has %v", value, env.StateDB.GetBalance(caller.Address()))
+		return nil, fmt.Errorf("insufficient funds to transfer value. Req %v, has %v", value, evm.StateDB.GetBalance(caller.Address()))
 	}
 
 	var (
-		snapshotPreTransfer = env.StateDB.Snapshot()
-		to                  = env.StateDB.GetAccount(caller.Address())
+		snapshot = evm.StateDB.Snapshot()
+		to       = evm.StateDB.GetAccount(caller.Address())
 	)
 	// initialise a new contract and set the code that is to be used by the
-	// E The contract is a scoped environment for this execution context
+	// E The contract is a scoped evmironment for this execution context
 	// only.
 	contract := NewContract(caller, to, value, gas)
-	contract.SetCallCode(&addr, env.StateDB.GetCodeHash(addr), env.StateDB.GetCode(addr))
+	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
 	defer contract.Finalise()
 
-	ret, err := env.EVM().Run(contract, input)
+	ret, err = evm.interpreter.Run(contract, input)
 	if err != nil {
 		contract.UseGas(contract.Gas)
 
-		env.StateDB.RevertToSnapshot(snapshotPreTransfer)
+		evm.StateDB.RevertToSnapshot(snapshot)
 	}
 
 	return ret, err
@@ -194,8 +208,8 @@ func (env *Environment) CallCode(caller ContractRef, addr common.Address, input
 //
 // DelegateCall differs from CallCode in the sense that it executes the given address' code with the caller as context
 // and the caller is set to the caller of the caller.
-func (env *Environment) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas *big.Int) ([]byte, error) {
-	if env.vmConfig.NoRecursion && env.Depth > 0 {
+func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas *big.Int) (ret []byte, err error) {
+	if evm.vmConfig.NoRecursion && evm.depth > 0 {
 		caller.ReturnGas(gas)
 
 		return nil, nil
@@ -203,34 +217,34 @@ func (env *Environment) DelegateCall(caller ContractRef, addr common.Address, in
 
 	// Depth check execution. Fail if we're trying to execute above the
 	// limit.
-	if env.Depth > int(params.CallCreateDepth.Int64()) {
+	if evm.depth > int(params.CallCreateDepth.Int64()) {
 		caller.ReturnGas(gas)
-		return nil, DepthError
+		return nil, ErrDepth
 	}
 
 	var (
-		snapshot = env.StateDB.Snapshot()
-		to       = env.StateDB.GetAccount(caller.Address())
+		snapshot = evm.StateDB.Snapshot()
+		to       = evm.StateDB.GetAccount(caller.Address())
 	)
 
 	// Iinitialise a new contract and make initialise the delegate values
 	contract := NewContract(caller, to, caller.Value(), gas).AsDelegate()
-	contract.SetCallCode(&addr, env.StateDB.GetCodeHash(addr), env.StateDB.GetCode(addr))
+	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
 	defer contract.Finalise()
 
-	ret, err := env.EVM().Run(contract, input)
+	ret, err = evm.interpreter.Run(contract, input)
 	if err != nil {
 		contract.UseGas(contract.Gas)
 
-		env.StateDB.RevertToSnapshot(snapshot)
+		evm.StateDB.RevertToSnapshot(snapshot)
 	}
 
 	return ret, err
 }
 
 // Create creates a new contract using code as deployment code.
-func (env *Environment) Create(caller ContractRef, code []byte, gas, value *big.Int) ([]byte, common.Address, error) {
-	if env.vmConfig.NoRecursion && env.Depth > 0 {
+func (evm *EVM) Create(caller ContractRef, code []byte, gas, value *big.Int) (ret []byte, contractAddr common.Address, err error) {
+	if evm.vmConfig.NoRecursion && evm.depth > 0 {
 		caller.ReturnGas(gas)
 
 		return nil, common.Address{}, nil
@@ -238,39 +252,38 @@ func (env *Environment) Create(caller ContractRef, code []byte, gas, value *big.
 
 	// Depth check execution. Fail if we're trying to execute above the
 	// limit.
-	if env.Depth > int(params.CallCreateDepth.Int64()) {
+	if evm.depth > int(params.CallCreateDepth.Int64()) {
 		caller.ReturnGas(gas)
 
-		return nil, common.Address{}, DepthError
+		return nil, common.Address{}, ErrDepth
 	}
-	if !env.CanTransfer(env.StateDB, caller.Address(), value) {
+	if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
 		caller.ReturnGas(gas)
 
 		return nil, common.Address{}, ErrInsufficientBalance
 	}
 
 	// Create a new account on the state
-	nonce := env.StateDB.GetNonce(caller.Address())
-	env.StateDB.SetNonce(caller.Address(), nonce+1)
-
-	snapshotPreTransfer := env.StateDB.Snapshot()
-	var (
-		addr = crypto.CreateAddress(caller.Address(), nonce)
-		to   = env.StateDB.CreateAccount(addr)
-	)
-	if env.ChainConfig().IsEIP158(env.BlockNumber) {
-		env.StateDB.SetNonce(addr, 1)
+	nonce := evm.StateDB.GetNonce(caller.Address())
+	evm.StateDB.SetNonce(caller.Address(), nonce+1)
+
+	snapshot := evm.StateDB.Snapshot()
+	contractAddr = crypto.CreateAddress(caller.Address(), nonce)
+	to := evm.StateDB.CreateAccount(contractAddr)
+	if evm.ChainConfig().IsEIP158(evm.BlockNumber) {
+		evm.StateDB.SetNonce(contractAddr, 1)
 	}
-	env.Transfer(env.StateDB, caller.Address(), to.Address(), value)
+	evm.Transfer(evm.StateDB, caller.Address(), to.Address(), value)
 
 	// initialise a new contract and set the code that is to be used by the
-	// E The contract is a scoped environment for this execution context
+	// E The contract is a scoped evmironment for this execution context
 	// only.
 	contract := NewContract(caller, to, value, gas)
-	contract.SetCallCode(&addr, crypto.Keccak256Hash(code), code)
+	contract.SetCallCode(&contractAddr, crypto.Keccak256Hash(code), code)
 	defer contract.Finalise()
 
-	ret, err := env.EVM().Run(contract, nil)
+	ret, err = evm.interpreter.Run(contract, nil)
+
 	// check whether the max code size has been exceeded
 	maxCodeSizeExceeded := len(ret) > params.MaxCodeSize
 	// if the contract creation ran successfully and no errors were returned
@@ -281,9 +294,9 @@ func (env *Environment) Create(caller ContractRef, code []byte, gas, value *big.
 		dataGas := big.NewInt(int64(len(ret)))
 		dataGas.Mul(dataGas, params.CreateDataGas)
 		if contract.UseGas(dataGas) {
-			env.StateDB.SetCode(addr, ret)
+			evm.StateDB.SetCode(contractAddr, ret)
 		} else {
-			err = CodeStoreOutOfGasError
+			err = ErrCodeStoreOutOfGas
 		}
 	}
 
@@ -291,12 +304,12 @@ func (env *Environment) Create(caller ContractRef, code []byte, gas, value *big.
 	// above we revert to the snapshot and consume any gas remaining. Additionally
 	// when we're in homestead this also counts for code storage gas errors.
 	if maxCodeSizeExceeded ||
-		(err != nil && (env.ChainConfig().IsHomestead(env.BlockNumber) || err != CodeStoreOutOfGasError)) {
+		(err != nil && (evm.ChainConfig().IsHomestead(evm.BlockNumber) || err != ErrCodeStoreOutOfGas)) {
 		contract.UseGas(contract.Gas)
-		env.StateDB.RevertToSnapshot(snapshotPreTransfer)
+		evm.StateDB.RevertToSnapshot(snapshot)
 
 		// Nothing should be returned when an error is thrown.
-		return nil, addr, err
+		return nil, contractAddr, err
 	}
 	// If the vm returned with an error the return value should be set to nil.
 	// This isn't consensus critical but merely to for behaviour reasons such as
@@ -305,11 +318,11 @@ func (env *Environment) Create(caller ContractRef, code []byte, gas, value *big.
 		ret = nil
 	}
 
-	return ret, addr, err
+	return ret, contractAddr, err
 }
 
-// ChainConfig returns the environment's chain configuration
-func (env *Environment) ChainConfig() *params.ChainConfig { return env.chainConfig }
+// ChainConfig returns the evmironment's chain configuration
+func (evm *EVM) ChainConfig() *params.ChainConfig { return evm.chainConfig }
 
-// EVM returns the environments EVM
-func (env *Environment) EVM() Vm { return env.evm }
+// Interpreter returns the EVM interpreter
+func (evm *EVM) Interpreter() *Interpreter { return evm.interpreter }