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, 165 insertions, 191 deletions

diff --git a/core/vm/instructions.go b/core/vm/instructions.go
index 871c09e83..2839b7109 100644
--- a/core/vm/instructions.go
+++ b/core/vm/instructions.go
@@ -26,128 +26,39 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
-type programInstruction interface {
-	// executes the program instruction and allows the instruction to modify the state of the program
-	do(program *Program, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) ([]byte, error)
-	// returns whether the program instruction halts the execution of the JIT
-	halts() bool
-	// Returns the current op code (debugging purposes)
-	Op() OpCode
-}
-
-type instrFn func(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack)
-
-type instruction struct {
-	op   OpCode
-	pc   uint64
-	fn   instrFn
-	data *big.Int
-
-	gas   *big.Int
-	spop  int
-	spush int
-
-	returns bool
-}
-
-func jump(mapping map[uint64]uint64, destinations map[uint64]struct{}, contract *Contract, to *big.Int) (uint64, error) {
-	if !validDest(destinations, to) {
-		nop := contract.GetOp(to.Uint64())
-		return 0, fmt.Errorf("invalid jump destination (%v) %v", nop, to)
-	}
-
-	return mapping[to.Uint64()], nil
-}
-
-func (instr instruction) do(program *Program, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	// calculate the new memory size and gas price for the current executing opcode
-	newMemSize, cost, err := jitCalculateGasAndSize(env, contract, instr, memory, stack)
-	if err != nil {
-		return nil, err
-	}
-
-	// Use the calculated gas. When insufficient gas is present, use all gas and return an
-	// Out Of Gas error
-	if !contract.UseGas(cost) {
-		return nil, OutOfGasError
-	}
-	// Resize the memory calculated previously
-	memory.Resize(newMemSize.Uint64())
-
-	// These opcodes return an argument and are therefor handled
-	// differently from the rest of the opcodes
-	switch instr.op {
-	case JUMP:
-		if pos, err := jump(program.mapping, program.destinations, contract, stack.pop()); err != nil {
-			return nil, err
-		} else {
-			*pc = pos
-			return nil, nil
-		}
-	case JUMPI:
-		pos, cond := stack.pop(), stack.pop()
-		if cond.Cmp(common.BigTrue) >= 0 {
-			if pos, err := jump(program.mapping, program.destinations, contract, pos); err != nil {
-				return nil, err
-			} else {
-				*pc = pos
-				return nil, nil
-			}
-		}
-	case RETURN:
-		offset, size := stack.pop(), stack.pop()
-		return memory.GetPtr(offset.Int64(), size.Int64()), nil
-	default:
-		if instr.fn == nil {
-			return nil, fmt.Errorf("Invalid opcode 0x%x", instr.op)
-		}
-		instr.fn(instr, pc, env, contract, memory, stack)
-	}
-	*pc++
-	return nil, nil
-}
-
-func (instr instruction) halts() bool {
-	return instr.returns
-}
-
-func (instr instruction) Op() OpCode {
-	return instr.op
-}
-
-func opStaticJump(instr instruction, pc *uint64, ret *big.Int, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
-	ret.Set(instr.data)
-}
-
-func opAdd(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opAdd(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(U256(x.Add(x, y)))
+	return nil, nil
 }
 
-func opSub(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opSub(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(U256(x.Sub(x, y)))
+	return nil, nil
 }
 
-func opMul(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opMul(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(U256(x.Mul(x, y)))
+	return nil, nil
 }
 
-func opDiv(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opDiv(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	if y.Cmp(common.Big0) != 0 {
 		stack.push(U256(x.Div(x, y)))
 	} else {
 		stack.push(new(big.Int))
 	}
+	return nil, nil
 }
 
-func opSdiv(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opSdiv(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := S256(stack.pop()), S256(stack.pop())
 	if y.Cmp(common.Big0) == 0 {
 		stack.push(new(big.Int))
-		return
+		return nil, nil
 	} else {
 		n := new(big.Int)
 		if new(big.Int).Mul(x, y).Cmp(common.Big0) < 0 {
@@ -161,18 +72,20 @@ func opSdiv(instr instruction, pc *uint64, env *Environment, contract *Contract,
 
 		stack.push(U256(res))
 	}
+	return nil, nil
 }
 
-func opMod(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opMod(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	if y.Cmp(common.Big0) == 0 {
 		stack.push(new(big.Int))
 	} else {
 		stack.push(U256(x.Mod(x, y)))
 	}
+	return nil, nil
 }
 
-func opSmod(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opSmod(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := S256(stack.pop()), S256(stack.pop())
 
 	if y.Cmp(common.Big0) == 0 {
@@ -190,14 +103,16 @@ func opSmod(instr instruction, pc *uint64, env *Environment, contract *Contract,
 
 		stack.push(U256(res))
 	}
+	return nil, nil
 }
 
-func opExp(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opExp(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	base, exponent := stack.pop(), stack.pop()
 	stack.push(math.Exp(base, exponent))
+	return nil, nil
 }
 
-func opSignExtend(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opSignExtend(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	back := stack.pop()
 	if back.Cmp(big.NewInt(31)) < 0 {
 		bit := uint(back.Uint64()*8 + 7)
@@ -212,80 +127,91 @@ func opSignExtend(instr instruction, pc *uint64, env *Environment, contract *Con
 
 		stack.push(U256(num))
 	}
+	return nil, nil
 }
 
-func opNot(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opNot(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x := stack.pop()
 	stack.push(U256(x.Not(x)))
+	return nil, nil
 }
 
-func opLt(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opLt(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	if x.Cmp(y) < 0 {
 		stack.push(big.NewInt(1))
 	} else {
 		stack.push(new(big.Int))
 	}
+	return nil, nil
 }
 
-func opGt(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opGt(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	if x.Cmp(y) > 0 {
 		stack.push(big.NewInt(1))
 	} else {
 		stack.push(new(big.Int))
 	}
+	return nil, nil
 }
 
-func opSlt(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opSlt(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := S256(stack.pop()), S256(stack.pop())
 	if x.Cmp(S256(y)) < 0 {
 		stack.push(big.NewInt(1))
 	} else {
 		stack.push(new(big.Int))
 	}
+	return nil, nil
 }
 
-func opSgt(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opSgt(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := S256(stack.pop()), S256(stack.pop())
 	if x.Cmp(y) > 0 {
 		stack.push(big.NewInt(1))
 	} else {
 		stack.push(new(big.Int))
 	}
+	return nil, nil
 }
 
-func opEq(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opEq(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	if x.Cmp(y) == 0 {
 		stack.push(big.NewInt(1))
 	} else {
 		stack.push(new(big.Int))
 	}
+	return nil, nil
 }
 
-func opIszero(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opIszero(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x := stack.pop()
 	if x.Cmp(common.Big0) > 0 {
 		stack.push(new(big.Int))
 	} else {
 		stack.push(big.NewInt(1))
 	}
+	return nil, nil
 }
 
-func opAnd(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opAnd(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(x.And(x, y))
+	return nil, nil
 }
-func opOr(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opOr(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(x.Or(x, y))
+	return nil, nil
 }
-func opXor(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opXor(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(x.Xor(x, y))
+	return nil, nil
 }
-func opByte(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opByte(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	th, val := stack.pop(), stack.pop()
 	if th.Cmp(big.NewInt(32)) < 0 {
 		byte := big.NewInt(int64(common.LeftPadBytes(val.Bytes(), 32)[th.Int64()]))
@@ -293,8 +219,9 @@ func opByte(instr instruction, pc *uint64, env *Environment, contract *Contract,
 	} else {
 		stack.push(new(big.Int))
 	}
+	return nil, nil
 }
-func opAddmod(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opAddmod(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y, z := stack.pop(), stack.pop(), stack.pop()
 	if z.Cmp(Zero) > 0 {
 		add := x.Add(x, y)
@@ -303,8 +230,9 @@ func opAddmod(instr instruction, pc *uint64, env *Environment, contract *Contrac
 	} else {
 		stack.push(new(big.Int))
 	}
+	return nil, nil
 }
-func opMulmod(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opMulmod(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y, z := stack.pop(), stack.pop(), stack.pop()
 	if z.Cmp(Zero) > 0 {
 		mul := x.Mul(x, y)
@@ -313,67 +241,79 @@ func opMulmod(instr instruction, pc *uint64, env *Environment, contract *Contrac
 	} else {
 		stack.push(new(big.Int))
 	}
+	return nil, nil
 }
 
-func opSha3(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opSha3(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	offset, size := stack.pop(), stack.pop()
 	hash := crypto.Keccak256(memory.Get(offset.Int64(), size.Int64()))
 
 	stack.push(common.BytesToBig(hash))
+	return nil, nil
 }
 
-func opAddress(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opAddress(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(common.Bytes2Big(contract.Address().Bytes()))
+	return nil, nil
 }
 
-func opBalance(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opBalance(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	addr := common.BigToAddress(stack.pop())
 	balance := env.StateDB.GetBalance(addr)
 
 	stack.push(new(big.Int).Set(balance))
+	return nil, nil
 }
 
-func opOrigin(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opOrigin(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(env.Origin.Big())
+	return nil, nil
 }
 
-func opCaller(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCaller(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(contract.Caller().Big())
+	return nil, nil
 }
 
-func opCallValue(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCallValue(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(new(big.Int).Set(contract.value))
+	return nil, nil
 }
 
-func opCalldataLoad(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCalldataLoad(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(common.Bytes2Big(getData(contract.Input, stack.pop(), common.Big32)))
+	return nil, nil
 }
 
-func opCalldataSize(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCalldataSize(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(big.NewInt(int64(len(contract.Input))))
+	return nil, nil
 }
 
-func opCalldataCopy(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCalldataCopy(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
 		mOff = stack.pop()
 		cOff = stack.pop()
 		l    = stack.pop()
 	)
 	memory.Set(mOff.Uint64(), l.Uint64(), getData(contract.Input, cOff, l))
+	return nil, nil
 }
 
-func opExtCodeSize(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opExtCodeSize(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	addr := common.BigToAddress(stack.pop())
 	l := big.NewInt(int64(env.StateDB.GetCodeSize(addr)))
 	stack.push(l)
+	return nil, nil
 }
 
-func opCodeSize(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCodeSize(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	l := big.NewInt(int64(len(contract.Code)))
 	stack.push(l)
+	return nil, nil
 }
 
-func opCodeCopy(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCodeCopy(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
 		mOff = stack.pop()
 		cOff = stack.pop()
@@ -382,9 +322,10 @@ func opCodeCopy(instr instruction, pc *uint64, env *Environment, contract *Contr
 	codeCopy := getData(contract.Code, cOff, l)
 
 	memory.Set(mOff.Uint64(), l.Uint64(), codeCopy)
+	return nil, nil
 }
 
-func opExtCodeCopy(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opExtCodeCopy(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
 		addr = common.BigToAddress(stack.pop())
 		mOff = stack.pop()
@@ -394,13 +335,15 @@ func opExtCodeCopy(instr instruction, pc *uint64, env *Environment, contract *Co
 	codeCopy := getData(env.StateDB.GetCode(addr), cOff, l)
 
 	memory.Set(mOff.Uint64(), l.Uint64(), codeCopy)
+	return nil, nil
 }
 
-func opGasprice(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opGasprice(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(new(big.Int).Set(env.GasPrice))
+	return nil, nil
 }
 
-func opBlockhash(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opBlockhash(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	num := stack.pop()
 
 	n := new(big.Int).Sub(env.BlockNumber, common.Big257)
@@ -409,106 +352,115 @@ func opBlockhash(instr instruction, pc *uint64, env *Environment, contract *Cont
 	} else {
 		stack.push(new(big.Int))
 	}
+	return nil, nil
 }
 
-func opCoinbase(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCoinbase(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(env.Coinbase.Big())
+	return nil, nil
 }
 
-func opTimestamp(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opTimestamp(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(U256(new(big.Int).Set(env.Time)))
+	return nil, nil
 }
 
-func opNumber(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opNumber(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(U256(new(big.Int).Set(env.BlockNumber)))
+	return nil, nil
 }
 
-func opDifficulty(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opDifficulty(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(U256(new(big.Int).Set(env.Difficulty)))
+	return nil, nil
 }
 
-func opGasLimit(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opGasLimit(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(U256(new(big.Int).Set(env.GasLimit)))
+	return nil, nil
 }
 
-func opPop(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opPop(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.pop()
+	return nil, nil
 }
 
-func opPush(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
-	stack.push(new(big.Int).Set(instr.data))
-}
-
-func opDup(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
-	stack.dup(int(instr.data.Int64()))
-}
-
-func opSwap(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
-	stack.swap(int(instr.data.Int64()))
-}
-
-func opLog(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
-	n := int(instr.data.Int64())
-	topics := make([]common.Hash, n)
-	mStart, mSize := stack.pop(), stack.pop()
-	for i := 0; i < n; i++ {
-		topics[i] = common.BigToHash(stack.pop())
-	}
-
-	d := memory.Get(mStart.Int64(), mSize.Int64())
-	log := NewLog(contract.Address(), topics, d, env.BlockNumber.Uint64())
-	env.StateDB.AddLog(log)
-}
-
-func opMload(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opMload(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	offset := stack.pop()
 	val := common.BigD(memory.Get(offset.Int64(), 32))
 	stack.push(val)
+	return nil, nil
 }
 
-func opMstore(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opMstore(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	// pop value of the stack
 	mStart, val := stack.pop(), stack.pop()
 	memory.Set(mStart.Uint64(), 32, common.BigToBytes(val, 256))
+	return nil, nil
 }
 
-func opMstore8(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opMstore8(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	off, val := stack.pop().Int64(), stack.pop().Int64()
 	memory.store[off] = byte(val & 0xff)
+	return nil, nil
 }
 
-func opSload(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opSload(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	loc := common.BigToHash(stack.pop())
 	val := env.StateDB.GetState(contract.Address(), loc).Big()
 	stack.push(val)
+	return nil, nil
 }
 
-func opSstore(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opSstore(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	loc := common.BigToHash(stack.pop())
 	val := stack.pop()
 	env.StateDB.SetState(contract.Address(), loc, common.BigToHash(val))
+	return nil, nil
 }
 
-func opJump(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opJump(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	pos := stack.pop()
+	if !contract.jumpdests.has(contract.CodeHash, contract.Code, pos) {
+		nop := contract.GetOp(pos.Uint64())
+		return nil, fmt.Errorf("invalid jump destination (%v) %v", nop, pos)
+	}
+	*pc = pos.Uint64()
+	return nil, nil
 }
-func opJumpi(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opJumpi(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	pos, cond := stack.pop(), stack.pop()
+	if cond.Cmp(common.BigTrue) >= 0 {
+		if !contract.jumpdests.has(contract.CodeHash, contract.Code, pos) {
+			nop := contract.GetOp(pos.Uint64())
+			return nil, fmt.Errorf("invalid jump destination (%v) %v", nop, pos)
+		}
+		*pc = pos.Uint64()
+	} else {
+		*pc++
+	}
+	return nil, nil
 }
-func opJumpdest(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opJumpdest(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	return nil, nil
 }
 
-func opPc(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
-	stack.push(new(big.Int).Set(instr.data))
+func opPc(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(new(big.Int).SetUint64(*pc))
+	return nil, nil
 }
 
-func opMsize(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opMsize(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(big.NewInt(int64(memory.Len())))
+	return nil, nil
 }
 
-func opGas(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opGas(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(new(big.Int).Set(contract.Gas))
+	return nil, nil
 }
 
-func opCreate(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCreate(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
 		value        = stack.pop()
 		offset, size = stack.pop(), stack.pop()
@@ -526,16 +478,17 @@ func opCreate(instr instruction, pc *uint64, env *Environment, contract *Contrac
 	// homestead we must check for CodeStoreOutOfGasError (homestead only
 	// rule) and treat as an error, if the ruleset is frontier we must
 	// ignore this error and pretend the operation was successful.
-	if env.ChainConfig().IsHomestead(env.BlockNumber) && suberr == CodeStoreOutOfGasError {
+	if env.ChainConfig().IsHomestead(env.BlockNumber) && suberr == ErrCodeStoreOutOfGas {
 		stack.push(new(big.Int))
-	} else if suberr != nil && suberr != CodeStoreOutOfGasError {
+	} else if suberr != nil && suberr != ErrCodeStoreOutOfGas {
 		stack.push(new(big.Int))
 	} else {
 		stack.push(addr.Big())
 	}
+	return nil, nil
 }
 
-func opCall(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCall(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	gas := stack.pop()
 	// pop gas and value of the stack.
 	addr, value := stack.pop(), stack.pop()
@@ -564,9 +517,10 @@ func opCall(instr instruction, pc *uint64, env *Environment, contract *Contract,
 
 		memory.Set(retOffset.Uint64(), retSize.Uint64(), ret)
 	}
+	return nil, nil
 }
 
-func opCallCode(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opCallCode(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	gas := stack.pop()
 	// pop gas and value of the stack.
 	addr, value := stack.pop(), stack.pop()
@@ -595,9 +549,16 @@ func opCallCode(instr instruction, pc *uint64, env *Environment, contract *Contr
 
 		memory.Set(retOffset.Uint64(), retSize.Uint64(), ret)
 	}
+	return nil, nil
 }
 
-func opDelegateCall(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opDelegateCall(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	// if not homestead return an error. DELEGATECALL is not supported
+	// during pre-homestead.
+	if !env.ChainConfig().IsHomestead(env.BlockNumber) {
+		return nil, fmt.Errorf("invalid opcode %x", DELEGATECALL)
+	}
+
 	gas, to, inOffset, inSize, outOffset, outSize := stack.pop(), stack.pop(), stack.pop(), stack.pop(), stack.pop(), stack.pop()
 
 	toAddr := common.BigToAddress(to)
@@ -609,25 +570,34 @@ func opDelegateCall(instr instruction, pc *uint64, env *Environment, contract *C
 		stack.push(big.NewInt(1))
 		memory.Set(outOffset.Uint64(), outSize.Uint64(), ret)
 	}
+	return nil, nil
 }
 
-func opReturn(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opReturn(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	offset, size := stack.pop(), stack.pop()
+	ret := memory.GetPtr(offset.Int64(), size.Int64())
+
+	return ret, nil
 }
-func opStop(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+
+func opStop(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	return nil, nil
 }
 
-func opSuicide(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func opSuicide(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	balance := env.StateDB.GetBalance(contract.Address())
 	env.StateDB.AddBalance(common.BigToAddress(stack.pop()), balance)
 
 	env.StateDB.Suicide(contract.Address())
+
+	return nil, nil
 }
 
 // following functions are used by the instruction jump  table
 
 // make log instruction function
-func makeLog(size int) instrFn {
-	return func(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func makeLog(size int) executionFunc {
+	return func(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 		topics := make([]common.Hash, size)
 		mStart, mSize := stack.pop(), stack.pop()
 		for i := 0; i < size; i++ {
@@ -637,30 +607,34 @@ func makeLog(size int) instrFn {
 		d := memory.Get(mStart.Int64(), mSize.Int64())
 		log := NewLog(contract.Address(), topics, d, env.BlockNumber.Uint64())
 		env.StateDB.AddLog(log)
+		return nil, nil
 	}
 }
 
 // make push instruction function
-func makePush(size uint64, bsize *big.Int) instrFn {
-	return func(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func makePush(size uint64, bsize *big.Int) executionFunc {
+	return func(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 		byts := getData(contract.Code, new(big.Int).SetUint64(*pc+1), bsize)
 		stack.push(common.Bytes2Big(byts))
 		*pc += size
+		return nil, nil
 	}
 }
 
 // make push instruction function
-func makeDup(size int64) instrFn {
-	return func(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+func makeDup(size int64) executionFunc {
+	return func(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 		stack.dup(int(size))
+		return nil, nil
 	}
 }
 
 // make swap instruction function
-func makeSwap(size int64) instrFn {
+func makeSwap(size int64) executionFunc {
 	// switch n + 1 otherwise n would be swapped with n
 	size += 1
-	return func(instr instruction, pc *uint64, env *Environment, contract *Contract, memory *Memory, stack *Stack) {
+	return func(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 		stack.swap(int(size))
+		return nil, nil
 	}
 }