core/vm: improved EVM run loop & instruction calling (ethereum#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.

accounts/abi/bind/backends/simulated.go

@@ -229,7 +229,7 @@ func (b *SimulatedBackend) callContract(ctx context.Context, call ethereum.CallM
 	evmContext := core.NewEVMContext(msg, block.Header(), b.blockchain)
 	// Create a new environment which holds all relevant information
 	// about the transaction and calling mechanisms.
-	vmenv := vm.NewEnvironment(evmContext, statedb, chainConfig, vm.Config{})
+	vmenv := vm.NewEVM(evmContext, statedb, chainConfig, vm.Config{})
 	gaspool := new(core.GasPool).AddGas(common.MaxBig)
 	ret, gasUsed, _, err := core.NewStateTransition(vmenv, msg, gaspool).TransitionDb()
 	return ret, gasUsed, err

cmd/evm/main.go

@@ -44,14 +44,6 @@ var (
 		Name:  "debug",
 		Usage: "output full trace logs",
 	}
-	ForceJitFlag = cli.BoolFlag{
-		Name:  "forcejit",
-		Usage: "forces jit compilation",
-	}
-	DisableJitFlag = cli.BoolFlag{
-		Name:  "nojit",
-		Usage: "disabled jit compilation",
-	}
 	CodeFlag = cli.StringFlag{
 		Name:  "code",
 		Usage: "EVM code",
@@ -95,15 +87,17 @@ var (
 		Name:  "create",
 		Usage: "indicates the action should be create rather than call",
 	}
+	DisableGasMeteringFlag = cli.BoolFlag{
+		Name:  "nogasmetering",
+		Usage: "disable gas metering",
+	}
 )
 
 func init() {
 	app.Flags = []cli.Flag{
 		CreateFlag,
 		DebugFlag,
 		VerbosityFlag,
-		ForceJitFlag,
-		DisableJitFlag,
 		SysStatFlag,
 		CodeFlag,
 		CodeFileFlag,
@@ -112,6 +106,7 @@ func init() {
 		ValueFlag,
 		DumpFlag,
 		InputFlag,
+		DisableGasMeteringFlag,
 	}
 	app.Action = run
 }
@@ -165,7 +160,8 @@ func run(ctx *cli.Context) error {
 			GasPrice: common.Big(ctx.GlobalString(PriceFlag.Name)),
 			Value:    common.Big(ctx.GlobalString(ValueFlag.Name)),
 			EVMConfig: vm.Config{
-				Tracer: logger,
+				Tracer:             logger,
+				DisableGasMetering: ctx.GlobalBool(DisableGasMeteringFlag.Name),
 			},
 		})
 	} else {
@@ -179,7 +175,8 @@ func run(ctx *cli.Context) error {
 			GasPrice: common.Big(ctx.GlobalString(PriceFlag.Name)),
 			Value:    common.Big(ctx.GlobalString(ValueFlag.Name)),
 			EVMConfig: vm.Config{
-				Tracer: logger,
+				Tracer:             logger,
+				DisableGasMetering: ctx.GlobalBool(DisableGasMeteringFlag.Name),
 			},
 		})
 	}

core/chain_makers.go

@@ -108,7 +108,7 @@ func (b *BlockGen) AddTx(tx *types.Transaction) {
 		b.SetCoinbase(common.Address{})
 	}
 	b.statedb.StartRecord(tx.Hash(), common.Hash{}, len(b.txs))
-	receipt, _, _, err := ApplyTransaction(b.config, nil, b.gasPool, b.statedb, b.header, tx, b.header.GasUsed, vm.Config{})
+	receipt, _, err := ApplyTransaction(b.config, nil, b.gasPool, b.statedb, b.header, tx, b.header.GasUsed, vm.Config{})
 	if err != nil {
 		panic(err)
 	}

core/state_processor.go

@@ -74,37 +74,36 @@ func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB, cfg
 	for i, tx := range block.Transactions() {
 		//fmt.Println("tx:", i)
 		statedb.StartRecord(tx.Hash(), block.Hash(), i)
-		receipt, logs, _, err := ApplyTransaction(p.config, p.bc, gp, statedb, header, tx, totalUsedGas, cfg)
+		receipt, _, err := ApplyTransaction(p.config, p.bc, gp, statedb, header, tx, totalUsedGas, cfg)
 		if err != nil {
 			return nil, nil, nil, err
 		}
 		receipts = append(receipts, receipt)
-		allLogs = append(allLogs, logs...)
+		allLogs = append(allLogs, receipt.Logs...)
 	}
 	AccumulateRewards(statedb, header, block.Uncles())
 
 	return receipts, allLogs, totalUsedGas, err
 }
 
 // ApplyTransaction attempts to apply a transaction to the given state database
-// and uses the input parameters for its environment.
-//
-// ApplyTransactions returns the generated receipts and vm logs during the
-// execution of the state transition phase.
-func ApplyTransaction(config *params.ChainConfig, bc *BlockChain, gp *GasPool, statedb *state.StateDB, header *types.Header, tx *types.Transaction, usedGas *big.Int, cfg vm.Config) (*types.Receipt, vm.Logs, *big.Int, error) {
+// and uses the input parameters for its environment. It returns the receipt
+// for the transaction, gas used and an error if the transaction failed,
+// indicating the block was invalid.
+func ApplyTransaction(config *params.ChainConfig, bc *BlockChain, gp *GasPool, statedb *state.StateDB, header *types.Header, tx *types.Transaction, usedGas *big.Int, cfg vm.Config) (*types.Receipt, *big.Int, error) {
 	msg, err := tx.AsMessage(types.MakeSigner(config, header.Number))
 	if err != nil {
-		return nil, nil, nil, err
+		return nil, nil, err
 	}
 	// Create a new context to be used in the EVM environment
 	context := NewEVMContext(msg, header, bc)
 	// Create a new environment which holds all relevant information
 	// about the transaction and calling mechanisms.
-	vmenv := vm.NewEnvironment(context, statedb, config, vm.Config{})
+	vmenv := vm.NewEVM(context, statedb, config, vm.Config{})
 	// Apply the transaction to the current state (included in the env)
 	_, gas, err := ApplyMessage(vmenv, msg, gp)
 	if err != nil {
-		return nil, nil, nil, err
+		return nil, nil, err
 	}
 
 	// Update the state with pending changes
@@ -125,7 +124,7 @@ func ApplyTransaction(config *params.ChainConfig, bc *BlockChain, gp *GasPool, s
 
 	glog.V(logger.Debug).Infoln(receipt)
 
-	return receipt, receipt.Logs, gas, err
+	return receipt, gas, err
 }
 
 // AccumulateRewards credits the coinbase of the given block with the

core/state_transition.go

@@ -57,7 +57,7 @@ type StateTransition struct {
 	data          []byte
 	state         vm.StateDB
 
-	env *vm.Environment
+	env *vm.EVM
 }
 
 // Message represents a message sent to a contract.
@@ -106,7 +106,7 @@ func IntrinsicGas(data []byte, contractCreation, homestead bool) *big.Int {
 }
 
 // NewStateTransition initialises and returns a new state transition object.
-func NewStateTransition(env *vm.Environment, msg Message, gp *GasPool) *StateTransition {
+func NewStateTransition(env *vm.EVM, msg Message, gp *GasPool) *StateTransition {
 	return &StateTransition{
 		gp:         gp,
 		env:        env,
@@ -127,7 +127,7 @@ func NewStateTransition(env *vm.Environment, msg Message, gp *GasPool) *StateTra
 // the gas used (which includes gas refunds) and an error if it failed. An error always
 // indicates a core error meaning that the message would always fail for that particular
 // state and would never be accepted within a block.
-func ApplyMessage(env *vm.Environment, msg Message, gp *GasPool) ([]byte, *big.Int, error) {
+func ApplyMessage(env *vm.EVM, msg Message, gp *GasPool) ([]byte, *big.Int, error) {
 	st := NewStateTransition(env, msg, gp)
 
 	ret, _, gasUsed, err := st.TransitionDb()
@@ -159,7 +159,7 @@ func (self *StateTransition) to() vm.Account {
 
 func (self *StateTransition) useGas(amount *big.Int) error {
 	if self.gas.Cmp(amount) < 0 {
-		return vm.OutOfGasError
+		return vm.ErrOutOfGas
 	}
 	self.gas.Sub(self.gas, amount)
 
@@ -233,7 +233,7 @@ func (self *StateTransition) TransitionDb() (ret []byte, requiredGas, usedGas *b
 	)
 	if contractCreation {
 		ret, _, vmerr = vmenv.Create(sender, self.data, self.gas, self.value)
-		if homestead && err == vm.CodeStoreOutOfGasError {
+		if homestead && err == vm.ErrCodeStoreOutOfGas {
 			self.gas = Big0
 		}
 	} else {

core/vm/contracts.go

@@ -26,64 +26,45 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
-// PrecompiledAccount represents a native ethereum contract
-type PrecompiledAccount struct {
-	Gas func(l int) *big.Int
-	fn  func(in []byte) []byte
+// Precompiled contract is the basic interface for native Go contracts. The implementation
+// requires a deterministic gas count based on the input size of the Run method of the
+// contract.
+type PrecompiledContract interface {
+	RequiredGas(inputSize int) *big.Int // RequiredPrice calculates the contract gas use
+	Run(input []byte) []byte            // Run runs the precompiled contract
 }
 
-// Call calls the native function
-func (self PrecompiledAccount) Call(in []byte) []byte {
-	return self.fn(in)
+// Precompiled contains the default set of ethereum contracts
+var PrecompiledContracts = map[common.Address]PrecompiledContract{
+	common.BytesToAddress([]byte{1}): &ecrecover{},
+	common.BytesToAddress([]byte{2}): &sha256{},
+	common.BytesToAddress([]byte{3}): &ripemd160{},
+	common.BytesToAddress([]byte{4}): &dataCopy{},
 }
 
-// Precompiled contains the default set of ethereum contracts
-var Precompiled = PrecompiledContracts()
-
-// PrecompiledContracts returns the default set of precompiled ethereum
-// contracts defined by the ethereum yellow paper.
-func PrecompiledContracts() map[string]*PrecompiledAccount {
-	return map[string]*PrecompiledAccount{
-		// ECRECOVER
-		string(common.LeftPadBytes([]byte{1}, 20)): &PrecompiledAccount{func(l int) *big.Int {
-			return params.EcrecoverGas
-		}, ecrecoverFunc},
-
-		// SHA256
-		string(common.LeftPadBytes([]byte{2}, 20)): &PrecompiledAccount{func(l int) *big.Int {
-			n := big.NewInt(int64(l+31) / 32)
-			n.Mul(n, params.Sha256WordGas)
-			return n.Add(n, params.Sha256Gas)
-		}, sha256Func},
-
-		// RIPEMD160
-		string(common.LeftPadBytes([]byte{3}, 20)): &PrecompiledAccount{func(l int) *big.Int {
-			n := big.NewInt(int64(l+31) / 32)
-			n.Mul(n, params.Ripemd160WordGas)
-			return n.Add(n, params.Ripemd160Gas)
-		}, ripemd160Func},
-
-		string(common.LeftPadBytes([]byte{4}, 20)): &PrecompiledAccount{func(l int) *big.Int {
-			n := big.NewInt(int64(l+31) / 32)
-			n.Mul(n, params.IdentityWordGas)
-
-			return n.Add(n, params.IdentityGas)
-		}, memCpy},
+// RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go
+func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error) {
+	gas := p.RequiredGas(len(input))
+	if contract.UseGas(gas) {
+		ret = p.Run(input)
+
+		return ret, nil
+	} else {
+		return nil, ErrOutOfGas
 	}
 }
 
-func sha256Func(in []byte) []byte {
-	return crypto.Sha256(in)
-}
+// ECRECOVER implemented as a native contract
+type ecrecover struct{}
 
-func ripemd160Func(in []byte) []byte {
-	return common.LeftPadBytes(crypto.Ripemd160(in), 32)
+func (c *ecrecover) RequiredGas(inputSize int) *big.Int {
+	return params.EcrecoverGas
 }
 
-const ecRecoverInputLength = 128
+func (c *ecrecover) Run(in []byte) []byte {
+	const ecRecoverInputLength = 128
 
-func ecrecoverFunc(in []byte) []byte {
-	in = common.RightPadBytes(in, 128)
+	in = common.RightPadBytes(in, ecRecoverInputLength)
 	// "in" is (hash, v, r, s), each 32 bytes
 	// but for ecrecover we want (r, s, v)
 
@@ -108,6 +89,39 @@ func ecrecoverFunc(in []byte) []byte {
 	return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32)
 }
 
-func memCpy(in []byte) []byte {
+// SHA256 implemented as a native contract
+type sha256 struct{}
+
+func (c *sha256) RequiredGas(inputSize int) *big.Int {
+	n := big.NewInt(int64(inputSize+31) / 32)
+	n.Mul(n, params.Sha256WordGas)
+	return n.Add(n, params.Sha256Gas)
+}
+func (c *sha256) Run(in []byte) []byte {
+	return crypto.Sha256(in)
+}
+
+// RIPMED160 implemented as a native contract
+type ripemd160 struct{}
+
+func (c *ripemd160) RequiredGas(inputSize int) *big.Int {
+	n := big.NewInt(int64(inputSize+31) / 32)
+	n.Mul(n, params.Ripemd160WordGas)
+	return n.Add(n, params.Ripemd160Gas)
+}
+func (c *ripemd160) Run(in []byte) []byte {
+	return common.LeftPadBytes(crypto.Ripemd160(in), 32)
+}
+
+// data copy implemented as a native contract
+type dataCopy struct{}
+
+func (c *dataCopy) RequiredGas(inputSize int) *big.Int {
+	n := big.NewInt(int64(inputSize+31) / 32)
+	n.Mul(n, params.IdentityWordGas)
+
+	return n.Add(n, params.IdentityGas)
+}
+func (c *dataCopy) Run(in []byte) []byte {
 	return in
 }