params: core, core/vm, miner: 64bit gas instructions

Reworked the EVM gas instructions to use 64bit integers rather than
arbitrary size big ints. All gas operations, be it additions,
multiplications or divisions, are checked and guarded against 64 bit
integer overflows.

In additon, most of the protocol paramaters in the params package have
been converted to uint64 and are now constants rather than variables.

* common/math: added overflow check ops
* core: vmenv, env renamed to evm
* eth, internal/ethapi, les: unmetered eth_call and cancel methods
* core/vm: implemented big.Int pool for evm instructions
* core/vm: unexported intPool methods & verification methods
* core/vm: added memoryGasCost overflow check and test

19 files changed, 777 insertions, 628 deletions

diff --git a/core/vm/common.go b/core/vm/common.go
index 2878b92d2..b7b9a6a9c 100644
--- a/core/vm/common.go
+++ b/core/vm/common.go
@@ -21,28 +21,11 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/params"
-)
-
-// Type is the VM type accepted by **NewVm**
-type Type byte
-
-const (
-	StdVmTy Type = iota // Default standard VM
-	JitVmTy             // LLVM JIT VM
-	MaxVmTy
 )
 
 var (
-	Pow256 = common.BigPow(2, 256) // Pow256 is 2**256
-
 	U256 = common.U256 // Shortcut to common.U256
 	S256 = common.S256 // Shortcut to common.S256
-
-	Zero = common.Big0 // Shortcut to common.Big0
-	One  = common.Big1 // Shortcut to common.Big1
-
-	max = big.NewInt(math.MaxInt64) // Maximum 64 bit integer
 )
 
 // calculates the memory size required for a step
@@ -54,48 +37,6 @@ func calcMemSize(off, l *big.Int) *big.Int {
 	return new(big.Int).Add(off, l)
 }
 
-// calculates the quadratic gas
-func quadMemGas(mem *Memory, newMemSize, gas *big.Int) {
-	if newMemSize.Cmp(common.Big0) > 0 {
-		newMemSizeWords := toWordSize(newMemSize)
-		newMemSize.Mul(newMemSizeWords, u256(32))
-
-		if newMemSize.Cmp(u256(int64(mem.Len()))) > 0 {
-			// be careful reusing variables here when changing.
-			// The order has been optimised to reduce allocation
-			oldSize := toWordSize(big.NewInt(int64(mem.Len())))
-			pow := new(big.Int).Exp(oldSize, common.Big2, Zero)
-			linCoef := oldSize.Mul(oldSize, params.MemoryGas)
-			quadCoef := new(big.Int).Div(pow, params.QuadCoeffDiv)
-			oldTotalFee := new(big.Int).Add(linCoef, quadCoef)
-
-			pow.Exp(newMemSizeWords, common.Big2, Zero)
-			linCoef = linCoef.Mul(newMemSizeWords, params.MemoryGas)
-			quadCoef = quadCoef.Div(pow, params.QuadCoeffDiv)
-			newTotalFee := linCoef.Add(linCoef, quadCoef)
-
-			fee := newTotalFee.Sub(newTotalFee, oldTotalFee)
-			gas.Add(gas, fee)
-		}
-	}
-}
-
-// Simple helper
-func u256(n int64) *big.Int {
-	return big.NewInt(n)
-}
-
-// Mainly used for print variables and passing to Print*
-func toValue(val *big.Int) interface{} {
-	// Let's assume a string on right padded zero's
-	b := val.Bytes()
-	if b[0] != 0 && b[len(b)-1] == 0x0 && b[len(b)-2] == 0x0 {
-		return string(b)
-	}
-
-	return val
-}
-
 // getData returns a slice from the data based on the start and size and pads
 // up to size with zero's. This function is overflow safe.
 func getData(data []byte, start, size *big.Int) []byte {
@@ -106,14 +47,17 @@ func getData(data []byte, start, size *big.Int) []byte {
 	return common.RightPadBytes(data[s.Uint64():e.Uint64()], int(size.Uint64()))
 }
 
-// useGas attempts to subtract the amount of gas and returns whether it was
-// successful
-func useGas(gas, amount *big.Int) bool {
-	if gas.Cmp(amount) < 0 {
-		return false
+// bigUint64 returns the integer casted to a uint64 and returns whether it
+// overflowed in the process.
+func bigUint64(v *big.Int) (uint64, bool) {
+	return v.Uint64(), v.BitLen() > 64
+}
+
+// toWordSize returns the ceiled word size required for memory expansion.
+func toWordSize(size uint64) uint64 {
+	if size > math.MaxUint64-31 {
+		return math.MaxUint64/32 + 1
 	}
 
-	// Sub the amount of gas from the remaining
-	gas.Sub(gas, amount)
-	return true
+	return (size + 31) / 32
 }
diff --git a/core/vm/contract.go b/core/vm/contract.go
index dfa93ab18..091106d84 100644
--- a/core/vm/contract.go
+++ b/core/vm/contract.go
@@ -24,7 +24,6 @@ import (
 
 // ContractRef is a reference to the contract's backing object
 type ContractRef interface {
-	ReturnGas(*big.Int)
 	Address() common.Address
 	Value() *big.Int
 	SetCode(common.Hash, []byte)
@@ -48,7 +47,8 @@ type Contract struct {
 	CodeAddr *common.Address
 	Input    []byte
 
-	value, Gas, UsedGas *big.Int
+	Gas   uint64
+	value *big.Int
 
 	Args []byte
 
@@ -56,7 +56,7 @@ type Contract struct {
 }
 
 // NewContract returns a new contract environment for the execution of EVM.
-func NewContract(caller ContractRef, object ContractRef, value, gas *big.Int) *Contract {
+func NewContract(caller ContractRef, object ContractRef, value *big.Int, gas uint64) *Contract {
 	c := &Contract{CallerAddress: caller.Address(), caller: caller, self: object, Args: nil}
 
 	if parent, ok := caller.(*Contract); ok {
@@ -68,9 +68,8 @@ func NewContract(caller ContractRef, object ContractRef, value, gas *big.Int) *C
 
 	// Gas should be a pointer so it can safely be reduced through the run
 	// This pointer will be off the state transition
-	c.Gas = gas //new(big.Int).Set(gas)
+	c.Gas = gas
 	c.value = new(big.Int).Set(value)
-	c.UsedGas = new(big.Int)
 
 	return c
 }
@@ -107,27 +106,13 @@ func (c *Contract) Caller() common.Address {
 	return c.CallerAddress
 }
 
-// Finalise finalises the contract and returning any remaining gas to the original
-// caller.
-func (c *Contract) Finalise() {
-	// Return the remaining gas to the caller
-	c.caller.ReturnGas(c.Gas)
-}
-
 // UseGas attempts the use gas and subtracts it and returns true on success
-func (c *Contract) UseGas(gas *big.Int) (ok bool) {
-	ok = useGas(c.Gas, gas)
-	if ok {
-		c.UsedGas.Add(c.UsedGas, gas)
+func (c *Contract) UseGas(gas uint64) (ok bool) {
+	if c.Gas < gas {
+		return false
 	}
-	return
-}
-
-// ReturnGas adds the given gas back to itself.
-func (c *Contract) ReturnGas(gas *big.Int) {
-	// Return the gas to the context
-	c.Gas.Add(c.Gas, gas)
-	c.UsedGas.Sub(c.UsedGas, gas)
+	c.Gas -= gas
+	return true
 }
 
 // Address returns the contracts address
diff --git a/core/vm/contracts.go b/core/vm/contracts.go
index 9645d268f..593b6ca55 100644
--- a/core/vm/contracts.go
+++ b/core/vm/contracts.go
@@ -17,8 +17,6 @@
 package vm
 
 import (
-	"math/big"
-
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/logger"
@@ -30,8 +28,8 @@ import (
 // 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
+	RequiredGas(inputSize int) uint64 // RequiredPrice calculates the contract gas use
+	Run(input []byte) []byte          // Run runs the precompiled contract
 }
 
 // Precompiled contains the default set of ethereum contracts
@@ -57,7 +55,7 @@ func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contr
 // ECRECOVER implemented as a native contract
 type ecrecover struct{}
 
-func (c *ecrecover) RequiredGas(inputSize int) *big.Int {
+func (c *ecrecover) RequiredGas(inputSize int) uint64 {
 	return params.EcrecoverGas
 }
 
@@ -92,10 +90,12 @@ func (c *ecrecover) Run(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)
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+//
+// This method does not require any overflow checking as the input size gas costs
+// required for anything significant is so high it's impossible to pay for.
+func (c *sha256) RequiredGas(inputSize int) uint64 {
+	return uint64(inputSize+31)/32*params.Sha256WordGas + params.Sha256Gas
 }
 func (c *sha256) Run(in []byte) []byte {
 	return crypto.Sha256(in)
@@ -104,10 +104,12 @@ func (c *sha256) Run(in []byte) []byte {
 // 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)
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+//
+// This method does not require any overflow checking as the input size gas costs
+// required for anything significant is so high it's impossible to pay for.
+func (c *ripemd160) RequiredGas(inputSize int) uint64 {
+	return uint64(inputSize+31)/32*params.Ripemd160WordGas + params.Ripemd160Gas
 }
 func (c *ripemd160) Run(in []byte) []byte {
 	return common.LeftPadBytes(crypto.Ripemd160(in), 32)
@@ -116,11 +118,12 @@ func (c *ripemd160) Run(in []byte) []byte {
 // 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)
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+//
+// This method does not require any overflow checking as the input size gas costs
+// required for anything significant is so high it's impossible to pay for.
+func (c *dataCopy) RequiredGas(inputSize int) uint64 {
+	return uint64(inputSize+31)/32*params.IdentityWordGas + params.IdentityGas
 }
 func (c *dataCopy) Run(in []byte) []byte {
 	return in
diff --git a/core/vm/environment.go b/core/vm/evm.go
index c19ef464b..0c5d998c2 100644
--- a/core/vm/environment.go
+++ b/core/vm/evm.go
@@ -17,7 +17,6 @@
 package vm
 
 import (
-	"fmt"
 	"math/big"
 	"sync/atomic"
 
@@ -102,24 +101,18 @@ func (evm *EVM) Cancel() {
 // Call executes the contract associated with the addr with the given input as parameters. 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 (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas, value *big.Int) (ret []byte, err error) {
+func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
 	if evm.vmConfig.NoRecursion && evm.depth > 0 {
-		caller.ReturnGas(gas)
-
-		return nil, nil
+		return nil, gas, nil
 	}
 
 	// Depth check execution. Fail if we're trying to execute above the
 	// limit.
-	if evm.depth > int(params.CallCreateDepth.Int64()) {
-		caller.ReturnGas(gas)
-
-		return nil, ErrDepth
+	if evm.depth > int(params.CallCreateDepth) {
+		return nil, gas, ErrDepth
 	}
 	if !evm.Context.CanTransfer(evm.StateDB, caller.Address(), value) {
-		caller.ReturnGas(gas)
-
-		return nil, ErrInsufficientBalance
+		return nil, gas, ErrInsufficientBalance
 	}
 
 	var (
@@ -128,8 +121,7 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas,
 	)
 	if !evm.StateDB.Exist(addr) {
 		if PrecompiledContracts[addr] == nil && evm.ChainConfig().IsEIP158(evm.BlockNumber) && value.BitLen() == 0 {
-			caller.ReturnGas(gas)
-			return nil, nil
+			return nil, gas, nil
 		}
 
 		to = evm.StateDB.CreateAccount(addr)
@@ -143,7 +135,6 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas,
 	// only.
 	contract := NewContract(caller, to, value, gas)
 	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
-	defer contract.Finalise()
 
 	ret, err = evm.interpreter.Run(contract, input)
 	// When an error was returned by the EVM or when setting the creation code
@@ -154,7 +145,7 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas,
 
 		evm.StateDB.RevertToSnapshot(snapshot)
 	}
-	return ret, err
+	return ret, contract.Gas, err
 }
 
 // CallCode executes the contract associated with the addr with the given input as parameters. It also handles any
@@ -162,24 +153,18 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas,
 // 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 (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte, gas, value *big.Int) (ret []byte, err error) {
+func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error) {
 	if evm.vmConfig.NoRecursion && evm.depth > 0 {
-		caller.ReturnGas(gas)
-
-		return nil, nil
+		return nil, gas, nil
 	}
 
 	// Depth check execution. Fail if we're trying to execute above the
 	// limit.
-	if evm.depth > int(params.CallCreateDepth.Int64()) {
-		caller.ReturnGas(gas)
-
-		return nil, ErrDepth
+	if evm.depth > int(params.CallCreateDepth) {
+		return nil, gas, ErrDepth
 	}
 	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, evm.StateDB.GetBalance(caller.Address()))
+		return nil, gas, ErrInsufficientBalance
 	}
 
 	var (
@@ -191,7 +176,6 @@ func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte,
 	// only.
 	contract := NewContract(caller, to, value, gas)
 	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
-	defer contract.Finalise()
 
 	ret, err = evm.interpreter.Run(contract, input)
 	if err != nil {
@@ -200,7 +184,7 @@ func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte,
 		evm.StateDB.RevertToSnapshot(snapshot)
 	}
 
-	return ret, err
+	return ret, contract.Gas, err
 }
 
 // DelegateCall executes the contract associated with the addr with the given input as parameters.
@@ -208,18 +192,15 @@ func (evm *EVM) CallCode(caller ContractRef, addr common.Address, input []byte,
 //
 // 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 (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas *big.Int) (ret []byte, err error) {
+func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []byte, gas uint64) (ret []byte, leftOverGas uint64, err error) {
 	if evm.vmConfig.NoRecursion && evm.depth > 0 {
-		caller.ReturnGas(gas)
-
-		return nil, nil
+		return nil, gas, nil
 	}
 
 	// Depth check execution. Fail if we're trying to execute above the
 	// limit.
-	if evm.depth > int(params.CallCreateDepth.Int64()) {
-		caller.ReturnGas(gas)
-		return nil, ErrDepth
+	if evm.depth > int(params.CallCreateDepth) {
+		return nil, gas, ErrDepth
 	}
 
 	var (
@@ -230,7 +211,6 @@ func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []by
 	// Iinitialise a new contract and make initialise the delegate values
 	contract := NewContract(caller, to, caller.Value(), gas).AsDelegate()
 	contract.SetCallCode(&addr, evm.StateDB.GetCodeHash(addr), evm.StateDB.GetCode(addr))
-	defer contract.Finalise()
 
 	ret, err = evm.interpreter.Run(contract, input)
 	if err != nil {
@@ -239,28 +219,22 @@ func (evm *EVM) DelegateCall(caller ContractRef, addr common.Address, input []by
 		evm.StateDB.RevertToSnapshot(snapshot)
 	}
 
-	return ret, err
+	return ret, contract.Gas, err
 }
 
 // Create creates a new contract using code as deployment code.
-func (evm *EVM) Create(caller ContractRef, code []byte, gas, value *big.Int) (ret []byte, contractAddr common.Address, err error) {
+func (evm *EVM) Create(caller ContractRef, code []byte, gas uint64, value *big.Int) (ret []byte, contractAddr common.Address, leftOverGas uint64, err error) {
 	if evm.vmConfig.NoRecursion && evm.depth > 0 {
-		caller.ReturnGas(gas)
-
-		return nil, common.Address{}, nil
+		return nil, common.Address{}, gas, nil
 	}
 
 	// Depth check execution. Fail if we're trying to execute above the
 	// limit.
-	if evm.depth > int(params.CallCreateDepth.Int64()) {
-		caller.ReturnGas(gas)
-
-		return nil, common.Address{}, ErrDepth
+	if evm.depth > int(params.CallCreateDepth) {
+		return nil, common.Address{}, gas, ErrDepth
 	}
 	if !evm.CanTransfer(evm.StateDB, caller.Address(), value) {
-		caller.ReturnGas(gas)
-
-		return nil, common.Address{}, ErrInsufficientBalance
+		return nil, common.Address{}, gas, ErrInsufficientBalance
 	}
 
 	// Create a new account on the state
@@ -280,7 +254,6 @@ func (evm *EVM) Create(caller ContractRef, code []byte, gas, value *big.Int) (re
 	// only.
 	contract := NewContract(caller, to, value, gas)
 	contract.SetCallCode(&contractAddr, crypto.Keccak256Hash(code), code)
-	defer contract.Finalise()
 
 	ret, err = evm.interpreter.Run(contract, nil)
 
@@ -291,9 +264,8 @@ func (evm *EVM) Create(caller ContractRef, code []byte, gas, value *big.Int) (re
 	// be stored due to not enough gas set an error and let it be handled
 	// by the error checking condition below.
 	if err == nil && !maxCodeSizeExceeded {
-		dataGas := big.NewInt(int64(len(ret)))
-		dataGas.Mul(dataGas, params.CreateDataGas)
-		if contract.UseGas(dataGas) {
+		createDataGas := uint64(len(ret)) * params.CreateDataGas
+		if contract.UseGas(createDataGas) {
 			evm.StateDB.SetCode(contractAddr, ret)
 		} else {
 			err = ErrCodeStoreOutOfGas
@@ -305,11 +277,10 @@ func (evm *EVM) Create(caller ContractRef, code []byte, gas, value *big.Int) (re
 	// when we're in homestead this also counts for code storage gas errors.
 	if maxCodeSizeExceeded ||
 		(err != nil && (evm.ChainConfig().IsHomestead(evm.BlockNumber) || err != ErrCodeStoreOutOfGas)) {
-		contract.UseGas(contract.Gas)
 		evm.StateDB.RevertToSnapshot(snapshot)
 
 		// Nothing should be returned when an error is thrown.
-		return nil, contractAddr, err
+		return nil, contractAddr, 0, 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
@@ -318,7 +289,7 @@ func (evm *EVM) Create(caller ContractRef, code []byte, gas, value *big.Int) (re
 		ret = nil
 	}
 
-	return ret, contractAddr, err
+	return ret, contractAddr, contract.Gas, err
 }
 
 // ChainConfig returns the evmironment's chain configuration
diff --git a/core/vm/gas.go b/core/vm/gas.go
index cb225b6ca..dd64d5f17 100644
--- a/core/vm/gas.go
+++ b/core/vm/gas.go
@@ -17,149 +17,42 @@
 package vm
 
 import (
-	"fmt"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/params"
 )
 
-var (
-	GasQuickStep   = big.NewInt(2)
-	GasFastestStep = big.NewInt(3)
-	GasFastStep    = big.NewInt(5)
-	GasMidStep     = big.NewInt(8)
-	GasSlowStep    = big.NewInt(10)
-	GasExtStep     = big.NewInt(20)
-
-	GasReturn = big.NewInt(0)
-	GasStop   = big.NewInt(0)
-
-	GasContractByte = big.NewInt(200)
-
-	n64 = big.NewInt(64)
+const (
+	GasQuickStep   uint64 = 2
+	GasFastestStep uint64 = 3
+	GasFastStep    uint64 = 5
+	GasMidStep     uint64 = 8
+	GasSlowStep    uint64 = 10
+	GasExtStep     uint64 = 20
+
+	GasReturn       uint64 = 0
+	GasStop         uint64 = 0
+	GasContractByte uint64 = 200
 )
 
 // calcGas returns the actual gas cost of the call.
 //
 // The cost of gas was changed during the homestead price change HF. To allow for EIP150
 // to be implemented. The returned gas is gas - base * 63 / 64.
-func callGas(gasTable params.GasTable, availableGas, base, callCost *big.Int) *big.Int {
-	if gasTable.CreateBySuicide != nil {
-		availableGas = new(big.Int).Sub(availableGas, base)
-		g := new(big.Int).Div(availableGas, n64)
-		g.Sub(availableGas, g)
-
-		if g.Cmp(callCost) < 0 {
-			return g
+func callGas(gasTable params.GasTable, availableGas, base uint64, callCost *big.Int) (uint64, error) {
+	if gasTable.CreateBySuicide > 0 {
+		availableGas = availableGas - base
+		gas := availableGas - availableGas/64
+		// If the bit length exceeds 64 bit we know that the newly calculated "gas" for EIP150
+		// is smaller than the requested amount. Therefor we return the new gas instead
+		// of returning an error.
+		if callCost.BitLen() > 64 || gas < callCost.Uint64() {
+			return gas, nil
 		}
 	}
-	return callCost
-}
-
-// baseCheck checks for any stack error underflows
-func baseCheck(op OpCode, stack *Stack, gas *big.Int) error {
-	// PUSH and DUP are a bit special. They all cost the same but we do want to have checking on stack push limit
-	// PUSH is also allowed to calculate the same price for all PUSHes
-	// DUP requirements are handled elsewhere (except for the stack limit check)
-	if op >= PUSH1 && op <= PUSH32 {
-		op = PUSH1
-	}
-	if op >= DUP1 && op <= DUP16 {
-		op = DUP1
-	}
-
-	if r, ok := _baseCheck[op]; ok {
-		err := stack.require(r.stackPop)
-		if err != nil {
-			return err
-		}
-
-		if r.stackPush > 0 && stack.len()-r.stackPop+r.stackPush > int(params.StackLimit.Int64()) {
-			return fmt.Errorf("stack limit reached %d (%d)", stack.len(), params.StackLimit.Int64())
-		}
-
-		gas.Add(gas, r.gas)
+	if callCost.BitLen() > 64 {
+		return 0, errGasUintOverflow
 	}
-	return nil
-}
-
-// casts a arbitrary number to the amount of words (sets of 32 bytes)
-func toWordSize(size *big.Int) *big.Int {
-	tmp := new(big.Int)
-	tmp.Add(size, u256(31))
-	tmp.Div(tmp, u256(32))
-	return tmp
-}
-
-type req struct {
-	stackPop  int
-	gas       *big.Int
-	stackPush int
-}
 
-var _baseCheck = map[OpCode]req{
-	// opcode  |  stack pop | gas price | stack push
-	ADD:          {2, GasFastestStep, 1},
-	LT:           {2, GasFastestStep, 1},
-	GT:           {2, GasFastestStep, 1},
-	SLT:          {2, GasFastestStep, 1},
-	SGT:          {2, GasFastestStep, 1},
-	EQ:           {2, GasFastestStep, 1},
-	ISZERO:       {1, GasFastestStep, 1},
-	SUB:          {2, GasFastestStep, 1},
-	AND:          {2, GasFastestStep, 1},
-	OR:           {2, GasFastestStep, 1},
-	XOR:          {2, GasFastestStep, 1},
-	NOT:          {1, GasFastestStep, 1},
-	BYTE:         {2, GasFastestStep, 1},
-	CALLDATALOAD: {1, GasFastestStep, 1},
-	CALLDATACOPY: {3, GasFastestStep, 1},
-	MLOAD:        {1, GasFastestStep, 1},
-	MSTORE:       {2, GasFastestStep, 0},
-	MSTORE8:      {2, GasFastestStep, 0},
-	CODECOPY:     {3, GasFastestStep, 0},
-	MUL:          {2, GasFastStep, 1},
-	DIV:          {2, GasFastStep, 1},
-	SDIV:         {2, GasFastStep, 1},
-	MOD:          {2, GasFastStep, 1},
-	SMOD:         {2, GasFastStep, 1},
-	SIGNEXTEND:   {2, GasFastStep, 1},
-	ADDMOD:       {3, GasMidStep, 1},
-	MULMOD:       {3, GasMidStep, 1},
-	JUMP:         {1, GasMidStep, 0},
-	JUMPI:        {2, GasSlowStep, 0},
-	EXP:          {2, GasSlowStep, 1},
-	ADDRESS:      {0, GasQuickStep, 1},
-	ORIGIN:       {0, GasQuickStep, 1},
-	CALLER:       {0, GasQuickStep, 1},
-	CALLVALUE:    {0, GasQuickStep, 1},
-	CODESIZE:     {0, GasQuickStep, 1},
-	GASPRICE:     {0, GasQuickStep, 1},
-	COINBASE:     {0, GasQuickStep, 1},
-	TIMESTAMP:    {0, GasQuickStep, 1},
-	NUMBER:       {0, GasQuickStep, 1},
-	CALLDATASIZE: {0, GasQuickStep, 1},
-	DIFFICULTY:   {0, GasQuickStep, 1},
-	GASLIMIT:     {0, GasQuickStep, 1},
-	POP:          {1, GasQuickStep, 0},
-	PC:           {0, GasQuickStep, 1},
-	MSIZE:        {0, GasQuickStep, 1},
-	GAS:          {0, GasQuickStep, 1},
-	BLOCKHASH:    {1, GasExtStep, 1},
-	BALANCE:      {1, Zero, 1},
-	EXTCODESIZE:  {1, Zero, 1},
-	EXTCODECOPY:  {4, Zero, 0},
-	SLOAD:        {1, params.SloadGas, 1},
-	SSTORE:       {2, Zero, 0},
-	SHA3:         {2, params.Sha3Gas, 1},
-	CREATE:       {3, params.CreateGas, 1},
-	// Zero is calculated in the gasSwitch
-	CALL:         {7, Zero, 1},
-	CALLCODE:     {7, Zero, 1},
-	DELEGATECALL: {6, Zero, 1},
-	SELFDESTRUCT: {1, Zero, 0},
-	JUMPDEST:     {0, params.JumpdestGas, 0},
-	RETURN:       {2, Zero, 0},
-	PUSH1:        {0, GasFastestStep, 1},
-	DUP1:         {0, Zero, 1},
+	return callCost.Uint64(), nil
 }
diff --git a/core/vm/gas_table.go b/core/vm/gas_table.go
index 4d2c4e94a..fba1eb066 100644
--- a/core/vm/gas_table.go
+++ b/core/vm/gas_table.go
@@ -1,56 +1,80 @@
 package vm
 
 import (
+	gmath "math"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/math"
 	"github.com/ethereum/go-ethereum/params"
 )
 
-func memoryGasCost(mem *Memory, newMemSize *big.Int) *big.Int {
-	gas := new(big.Int)
-	if newMemSize.Cmp(common.Big0) > 0 {
-		newMemSizeWords := toWordSize(newMemSize)
-
-		if newMemSize.Cmp(u256(int64(mem.Len()))) > 0 {
-			// be careful reusing variables here when changing.
-			// The order has been optimised to reduce allocation
-			oldSize := toWordSize(big.NewInt(int64(mem.Len())))
-			pow := new(big.Int).Exp(oldSize, common.Big2, Zero)
-			linCoef := oldSize.Mul(oldSize, params.MemoryGas)
-			quadCoef := new(big.Int).Div(pow, params.QuadCoeffDiv)
-			oldTotalFee := new(big.Int).Add(linCoef, quadCoef)
-
-			pow.Exp(newMemSizeWords, common.Big2, Zero)
-			linCoef = linCoef.Mul(newMemSizeWords, params.MemoryGas)
-			quadCoef = quadCoef.Div(pow, params.QuadCoeffDiv)
-			newTotalFee := linCoef.Add(linCoef, quadCoef)
-
-			fee := newTotalFee.Sub(newTotalFee, oldTotalFee)
-			gas.Add(gas, fee)
-		}
+// memoryGasCosts calculates the quadratic gas for memory expansion. It does so
+// only for the memory region that is expanded, not the total memory.
+func memoryGasCost(mem *Memory, newMemSize uint64) (uint64, error) {
+	// The maximum that will fit in a uint64 is max_word_count - 1
+	// anything above that will result in an overflow.
+	if newMemSize > gmath.MaxUint64-32 {
+		return 0, errGasUintOverflow
+	}
+
+	if newMemSize == 0 {
+		return 0, nil
 	}
-	return gas
+
+	newMemSizeWords := toWordSize(newMemSize)
+	newMemSize = newMemSizeWords * 32
+
+	if newMemSize > uint64(mem.Len()) {
+		square := newMemSizeWords * newMemSizeWords
+		linCoef := newMemSizeWords * params.MemoryGas
+		quadCoef := square / params.QuadCoeffDiv
+		newTotalFee := linCoef + quadCoef
+
+		fee := newTotalFee - mem.lastGasCost
+		mem.lastGasCost = newTotalFee
+
+		return fee, nil
+	}
+	return 0, nil
 }
 
-func constGasFunc(gas *big.Int) gasFunc {
-	return func(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-		return gas
+func constGasFunc(gas uint64) gasFunc {
+	return func(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+		return gas, nil
 	}
 }
 
-func gasCalldataCopy(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	gas := memoryGasCost(mem, memorySize)
-	gas.Add(gas, GasFastestStep)
-	words := toWordSize(stack.Back(2))
+func gasCalldataCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	gas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, err
+	}
+
+	var overflow bool
+	if gas, overflow = math.SafeAdd(gas, GasFastestStep); overflow {
+		return 0, errGasUintOverflow
+	}
 
-	return gas.Add(gas, words.Mul(words, params.CopyGas))
+	words, overflow := bigUint64(stack.Back(2))
+	if overflow {
+		return 0, errGasUintOverflow
+	}
+
+	if words, overflow = math.SafeMul(toWordSize(words), params.CopyGas); overflow {
+		return 0, errGasUintOverflow
+	}
+
+	if gas, overflow = math.SafeAdd(gas, words); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasSStore(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
+func gasSStore(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
 	var (
 		y, x = stack.Back(1), stack.Back(0)
-		val  = env.StateDB.GetState(contract.Address(), common.BigToHash(x))
+		val  = evm.StateDB.GetState(contract.Address(), common.BigToHash(x))
 	)
 	// This checks for 3 scenario's and calculates gas accordingly
 	// 1. From a zero-value address to a non-zero value         (NEW VALUE)
@@ -58,189 +82,335 @@ func gasSStore(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, m
 	// 3. From a non-zero to a non-zero                         (CHANGE)
 	if common.EmptyHash(val) && !common.EmptyHash(common.BigToHash(y)) {
 		// 0 => non 0
-		return new(big.Int).Set(params.SstoreSetGas)
+		return params.SstoreSetGas, nil
 	} else if !common.EmptyHash(val) && common.EmptyHash(common.BigToHash(y)) {
-		env.StateDB.AddRefund(params.SstoreRefundGas)
+		evm.StateDB.AddRefund(new(big.Int).SetUint64(params.SstoreRefundGas))
 
-		return new(big.Int).Set(params.SstoreClearGas)
+		return params.SstoreClearGas, nil
 	} else {
 		// non 0 => non 0 (or 0 => 0)
-		return new(big.Int).Set(params.SstoreResetGas)
+		return params.SstoreResetGas, nil
 	}
 }
 
-func makeGasLog(n uint) gasFunc {
-	return func(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-		mSize := stack.Back(1)
+func makeGasLog(n uint64) gasFunc {
+	return func(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+		requestedSize, overflow := bigUint64(stack.Back(1))
+		if overflow {
+			return 0, errGasUintOverflow
+		}
 
-		gas := new(big.Int).Add(memoryGasCost(mem, memorySize), params.LogGas)
-		gas.Add(gas, new(big.Int).Mul(big.NewInt(int64(n)), params.LogTopicGas))
-		gas.Add(gas, new(big.Int).Mul(mSize, params.LogDataGas))
-		return gas
+		gas, err := memoryGasCost(mem, memorySize)
+		if err != nil {
+			return 0, err
+		}
+
+		if gas, overflow = math.SafeAdd(gas, params.LogGas); overflow {
+			return 0, errGasUintOverflow
+		}
+		if gas, overflow = math.SafeAdd(gas, n*params.LogTopicGas); overflow {
+			return 0, errGasUintOverflow
+		}
+
+		var memorySizeGas uint64
+		if memorySizeGas, overflow = math.SafeMul(requestedSize, params.LogDataGas); overflow {
+			return 0, errGasUintOverflow
+		}
+		if gas, overflow = math.SafeAdd(gas, memorySizeGas); overflow {
+			return 0, errGasUintOverflow
+		}
+		return gas, nil
 	}
 }
 
-func gasSha3(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	gas := memoryGasCost(mem, memorySize)
-	gas.Add(gas, params.Sha3Gas)
-	words := toWordSize(stack.Back(1))
-	return gas.Add(gas, words.Mul(words, params.Sha3WordGas))
-}
+func gasSha3(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	var overflow bool
+	gas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, err
+	}
 
-func gasCodeCopy(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	gas := memoryGasCost(mem, memorySize)
-	gas.Add(gas, GasFastestStep)
-	words := toWordSize(stack.Back(2))
+	if gas, overflow = math.SafeAdd(gas, params.Sha3Gas); overflow {
+		return 0, errGasUintOverflow
+	}
 
-	return gas.Add(gas, words.Mul(words, params.CopyGas))
+	wordGas, overflow := bigUint64(stack.Back(1))
+	if overflow {
+		return 0, errGasUintOverflow
+	}
+	if wordGas, overflow = math.SafeMul(toWordSize(wordGas), params.Sha3WordGas); overflow {
+		return 0, errGasUintOverflow
+	}
+	if gas, overflow = math.SafeAdd(gas, wordGas); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasExtCodeCopy(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	gas := memoryGasCost(mem, memorySize)
-	gas.Add(gas, gt.ExtcodeCopy)
-	words := toWordSize(stack.Back(3))
+func gasCodeCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	gas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, err
+	}
+
+	var overflow bool
+	if gas, overflow = math.SafeAdd(gas, GasFastestStep); overflow {
+		return 0, errGasUintOverflow
+	}
 
-	return gas.Add(gas, words.Mul(words, params.CopyGas))
+	wordGas, overflow := bigUint64(stack.Back(2))
+	if overflow {
+		return 0, errGasUintOverflow
+	}
+	if wordGas, overflow = math.SafeMul(toWordSize(wordGas), params.CopyGas); overflow {
+		return 0, errGasUintOverflow
+	}
+	if gas, overflow = math.SafeAdd(gas, wordGas); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasMLoad(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	return new(big.Int).Add(GasFastestStep, memoryGasCost(mem, memorySize))
+func gasExtCodeCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	gas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, err
+	}
+
+	var overflow bool
+	if gas, overflow = math.SafeAdd(gas, gt.ExtcodeCopy); overflow {
+		return 0, errGasUintOverflow
+	}
+
+	wordGas, overflow := bigUint64(stack.Back(3))
+	if overflow {
+		return 0, errGasUintOverflow
+	}
+
+	if wordGas, overflow = math.SafeMul(toWordSize(wordGas), params.CopyGas); overflow {
+		return 0, errGasUintOverflow
+	}
+
+	if gas, overflow = math.SafeAdd(gas, wordGas); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasMStore8(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	return new(big.Int).Add(GasFastestStep, memoryGasCost(mem, memorySize))
+func gasMLoad(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	var overflow bool
+	gas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, errGasUintOverflow
+	}
+	if gas, overflow = math.SafeAdd(gas, GasFastestStep); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasMStore(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	return new(big.Int).Add(GasFastestStep, memoryGasCost(mem, memorySize))
+func gasMStore8(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	var overflow bool
+	gas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, errGasUintOverflow
+	}
+	if gas, overflow = math.SafeAdd(gas, GasFastestStep); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasCreate(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	return new(big.Int).Add(params.CreateGas, memoryGasCost(mem, memorySize))
+func gasMStore(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	var overflow bool
+	gas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, errGasUintOverflow
+	}
+	if gas, overflow = math.SafeAdd(gas, GasFastestStep); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasBalance(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	return gt.Balance
+func gasCreate(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	var overflow bool
+	gas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, err
+	}
+	if gas, overflow = math.SafeAdd(gas, params.CreateGas); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasExtCodeSize(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	return gt.ExtcodeSize
+func gasBalance(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	return gt.Balance, nil
 }
 
-func gasSLoad(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	return gt.SLoad
+func gasExtCodeSize(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	return gt.ExtcodeSize, nil
 }
 
-func gasExp(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	expByteLen := int64((stack.data[stack.len()-2].BitLen() + 7) / 8)
-	gas := big.NewInt(expByteLen)
-	gas.Mul(gas, gt.ExpByte)
-	return gas.Add(gas, GasSlowStep)
+func gasSLoad(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	return gt.SLoad, nil
 }
 
-func gasCall(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	gas := new(big.Int).Set(gt.Calls)
+func gasExp(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	expByteLen := uint64((stack.data[stack.len()-2].BitLen() + 7) / 8)
 
-	transfersValue := stack.Back(2).BitLen() > 0
 	var (
-		address = common.BigToAddress(stack.Back(1))
-		eip158  = env.ChainConfig().IsEIP158(env.BlockNumber)
+		gas      = expByteLen * gt.ExpByte // no overflow check required. Max is 256 * ExpByte gas
+		overflow bool
+	)
+	if gas, overflow = math.SafeAdd(gas, GasSlowStep); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
+}
+
+func gasCall(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	var (
+		gas            = gt.Calls
+		transfersValue = stack.Back(2).BitLen() > 0
+		address        = common.BigToAddress(stack.Back(1))
+		eip158         = evm.ChainConfig().IsEIP158(evm.BlockNumber)
 	)
 	if eip158 {
-		if env.StateDB.Empty(address) && transfersValue {
-			gas.Add(gas, params.CallNewAccountGas)
+		if evm.StateDB.Empty(address) && transfersValue {
+			gas += params.CallNewAccountGas
 		}
-	} else if !env.StateDB.Exist(address) {
-		gas.Add(gas, params.CallNewAccountGas)
+	} else if !evm.StateDB.Exist(address) {
+		gas += params.CallNewAccountGas
 	}
 	if transfersValue {
-		gas.Add(gas, params.CallValueTransferGas)
+		gas += params.CallValueTransferGas
+	}
+	memoryGas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, err
+	}
+	var overflow bool
+	if gas, overflow = math.SafeAdd(gas, memoryGas); overflow {
+		return 0, errGasUintOverflow
 	}
-	gas.Add(gas, memoryGasCost(mem, memorySize))
 
-	cg := callGas(gt, contract.Gas, gas, stack.data[stack.len()-1])
+	cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+	if err != nil {
+		return 0, err
+	}
 	// Replace the stack item with the new gas calculation. This means that
 	// either the original item is left on the stack or the item is replaced by:
 	// (availableGas - gas) * 63 / 64
 	// We replace the stack item so that it's available when the opCall instruction is
 	// called. This information is otherwise lost due to the dependency on *current*
 	// available gas.
-	stack.data[stack.len()-1] = cg
+	stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
 
-	return gas.Add(gas, cg)
+	if gas, overflow = math.SafeAdd(gas, cg); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasCallCode(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	gas := new(big.Int).Set(gt.Calls)
+func gasCallCode(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	gas := gt.Calls
 	if stack.Back(2).BitLen() > 0 {
-		gas.Add(gas, params.CallValueTransferGas)
+		gas += params.CallValueTransferGas
+	}
+	memoryGas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, err
+	}
+	var overflow bool
+	if gas, overflow = math.SafeAdd(gas, memoryGas); overflow {
+		return 0, errGasUintOverflow
 	}
-	gas.Add(gas, memoryGasCost(mem, memorySize))
 
-	cg := callGas(gt, contract.Gas, gas, stack.data[stack.len()-1])
+	cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+	if err != nil {
+		return 0, err
+	}
 	// Replace the stack item with the new gas calculation. This means that
 	// either the original item is left on the stack or the item is replaced by:
 	// (availableGas - gas) * 63 / 64
 	// We replace the stack item so that it's available when the opCall instruction is
 	// called. This information is otherwise lost due to the dependency on *current*
 	// available gas.
-	stack.data[stack.len()-1] = cg
+	stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
 
-	return gas.Add(gas, cg)
+	if gas, overflow = math.SafeAdd(gas, cg); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasReturn(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
+func gasReturn(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
 	return memoryGasCost(mem, memorySize)
 }
 
-func gasSuicide(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	gas := new(big.Int)
+func gasSuicide(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	var gas uint64
 	// EIP150 homestead gas reprice fork:
-	if env.ChainConfig().IsEIP150(env.BlockNumber) {
-		gas.Set(gt.Suicide)
+	if evm.ChainConfig().IsEIP150(evm.BlockNumber) {
+		gas = gt.Suicide
 		var (
 			address = common.BigToAddress(stack.Back(0))
-			eip158  = env.ChainConfig().IsEIP158(env.BlockNumber)
+			eip158  = evm.ChainConfig().IsEIP158(evm.BlockNumber)
 		)
 
 		if eip158 {
 			// if empty and transfers value
-			if env.StateDB.Empty(address) && env.StateDB.GetBalance(contract.Address()).BitLen() > 0 {
-				gas.Add(gas, gt.CreateBySuicide)
+			if evm.StateDB.Empty(address) && evm.StateDB.GetBalance(contract.Address()).BitLen() > 0 {
+				gas += gt.CreateBySuicide
 			}
-		} else if !env.StateDB.Exist(address) {
-			gas.Add(gas, gt.CreateBySuicide)
+		} else if !evm.StateDB.Exist(address) {
+			gas += gt.CreateBySuicide
 		}
 	}
 
-	if !env.StateDB.HasSuicided(contract.Address()) {
-		env.StateDB.AddRefund(params.SuicideRefundGas)
+	if !evm.StateDB.HasSuicided(contract.Address()) {
+		evm.StateDB.AddRefund(new(big.Int).SetUint64(params.SuicideRefundGas))
 	}
-	return gas
+	return gas, nil
 }
 
-func gasDelegateCall(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	gas := new(big.Int).Add(gt.Calls, memoryGasCost(mem, memorySize))
+func gasDelegateCall(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	gas, err := memoryGasCost(mem, memorySize)
+	if err != nil {
+		return 0, err
+	}
+	var overflow bool
+	if gas, overflow = math.SafeAdd(gas, gt.Calls); overflow {
+		return 0, errGasUintOverflow
+	}
 
-	cg := callGas(gt, contract.Gas, gas, stack.data[stack.len()-1])
+	cg, err := callGas(gt, contract.Gas, gas, stack.Back(0))
+	if err != nil {
+		return 0, err
+	}
 	// Replace the stack item with the new gas calculation. This means that
 	// either the original item is left on the stack or the item is replaced by:
 	// (availableGas - gas) * 63 / 64
 	// We replace the stack item so that it's available when the opCall instruction is
 	// called.
-	stack.data[stack.len()-1] = cg
+	stack.data[stack.len()-1] = new(big.Int).SetUint64(cg)
 
-	return gas.Add(gas, cg)
+	if gas, overflow = math.SafeAdd(gas, cg); overflow {
+		return 0, errGasUintOverflow
+	}
+	return gas, nil
 }
 
-func gasPush(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	return GasFastestStep
+func gasPush(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	return GasFastestStep, nil
 }
 
-func gasSwap(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	return GasFastestStep
+func gasSwap(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	return GasFastestStep, nil
 }
 
-func gasDup(gt params.GasTable, env *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize *big.Int) *big.Int {
-	return GasFastestStep
+func gasDup(gt params.GasTable, evm *EVM, contract *Contract, stack *Stack, mem *Memory, memorySize uint64) (uint64, error) {
+	return GasFastestStep, nil
 }
diff --git a/core/vm/gas_table_test.go b/core/vm/gas_table_test.go
new file mode 100644
index 000000000..cceb89285
--- /dev/null
+++ b/core/vm/gas_table_test.go
@@ -0,0 +1,24 @@
+package vm
+
+import (
+	"math"
+	"testing"
+)
+
+func TestMemoryGasCost(t *testing.T) {
+	size := uint64(math.MaxUint64 - 64)
+	_, err := memoryGasCost(&Memory{}, size)
+	if err != nil {
+		t.Error("didn't expect error:", err)
+	}
+
+	_, err = memoryGasCost(&Memory{}, size+32)
+	if err != nil {
+		t.Error("didn't expect error:", err)
+	}
+
+	_, err = memoryGasCost(&Memory{}, size+33)
+	if err == nil {
+		t.Error("expected error")
+	}
+}
diff --git a/core/vm/instructions.go b/core/vm/instructions.go
index 3b1b06cca..39e5c0587 100644
--- a/core/vm/instructions.go
+++ b/core/vm/instructions.go
@@ -27,42 +27,56 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
-func opAdd(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+var bigZero = new(big.Int)
+
+func opAdd(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(U256(x.Add(x, y)))
+
+	evm.interpreter.intPool.put(y)
+
 	return nil, nil
 }
 
-func opSub(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opSub(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(U256(x.Sub(x, y)))
+
+	evm.interpreter.intPool.put(y)
+
 	return nil, nil
 }
 
-func opMul(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opMul(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(U256(x.Mul(x, y)))
+
+	evm.interpreter.intPool.put(y)
+
 	return nil, nil
 }
 
-func opDiv(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opDiv(pc *uint64, evm *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))
 	}
+
+	evm.interpreter.intPool.put(y)
+
 	return nil, nil
 }
 
-func opSdiv(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opSdiv(pc *uint64, evm *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 nil, nil
 	} else {
 		n := new(big.Int)
-		if new(big.Int).Mul(x, y).Cmp(common.Big0) < 0 {
+		if evm.interpreter.intPool.get().Mul(x, y).Cmp(common.Big0) < 0 {
 			n.SetInt64(-1)
 		} else {
 			n.SetInt64(1)
@@ -73,20 +87,22 @@ func opSdiv(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Sta
 
 		stack.push(U256(res))
 	}
+	evm.interpreter.intPool.put(y)
 	return nil, nil
 }
 
-func opMod(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opMod(pc *uint64, evm *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)))
 	}
+	evm.interpreter.intPool.put(y)
 	return nil, nil
 }
 
-func opSmod(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opSmod(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := S256(stack.pop()), S256(stack.pop())
 
 	if y.Cmp(common.Big0) == 0 {
@@ -104,16 +120,20 @@ func opSmod(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Sta
 
 		stack.push(U256(res))
 	}
+	evm.interpreter.intPool.put(y)
 	return nil, nil
 }
 
-func opExp(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opExp(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	base, exponent := stack.pop(), stack.pop()
 	stack.push(math.Exp(base, exponent))
+
+	evm.interpreter.intPool.put(base, exponent)
+
 	return nil, nil
 }
 
-func opSignExtend(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opSignExtend(pc *uint64, evm *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)
@@ -128,198 +148,231 @@ func opSignExtend(pc *uint64, env *EVM, contract *Contract, memory *Memory, stac
 
 		stack.push(U256(num))
 	}
+
+	evm.interpreter.intPool.put(back)
 	return nil, nil
 }
 
-func opNot(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opNot(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x := stack.pop()
 	stack.push(U256(x.Not(x)))
 	return nil, nil
 }
 
-func opLt(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opLt(pc *uint64, evm *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))
+		stack.push(evm.interpreter.intPool.get().SetUint64(1))
 	} else {
 		stack.push(new(big.Int))
 	}
+
+	evm.interpreter.intPool.put(x, y)
 	return nil, nil
 }
 
-func opGt(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opGt(pc *uint64, evm *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))
+		stack.push(evm.interpreter.intPool.get().SetUint64(1))
 	} else {
 		stack.push(new(big.Int))
 	}
+
+	evm.interpreter.intPool.put(x, y)
 	return nil, nil
 }
 
-func opSlt(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opSlt(pc *uint64, evm *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))
+		stack.push(evm.interpreter.intPool.get().SetUint64(1))
 	} else {
 		stack.push(new(big.Int))
 	}
+
+	evm.interpreter.intPool.put(x, y)
 	return nil, nil
 }
 
-func opSgt(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opSgt(pc *uint64, evm *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))
+		stack.push(evm.interpreter.intPool.get().SetUint64(1))
 	} else {
 		stack.push(new(big.Int))
 	}
+
+	evm.interpreter.intPool.put(x, y)
 	return nil, nil
 }
 
-func opEq(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opEq(pc *uint64, evm *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))
+		stack.push(evm.interpreter.intPool.get().SetUint64(1))
 	} else {
 		stack.push(new(big.Int))
 	}
+
+	evm.interpreter.intPool.put(x, y)
 	return nil, nil
 }
 
-func opIszero(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opIszero(pc *uint64, evm *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))
+		stack.push(evm.interpreter.intPool.get().SetUint64(1))
 	}
+
+	evm.interpreter.intPool.put(x)
 	return nil, nil
 }
 
-func opAnd(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opAnd(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(x.And(x, y))
+
+	evm.interpreter.intPool.put(y)
 	return nil, nil
 }
-func opOr(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opOr(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(x.Or(x, y))
+
+	evm.interpreter.intPool.put(y)
 	return nil, nil
 }
-func opXor(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opXor(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y := stack.pop(), stack.pop()
 	stack.push(x.Xor(x, y))
+
+	evm.interpreter.intPool.put(y)
 	return nil, nil
 }
-func opByte(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opByte(pc *uint64, evm *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()]))
+		byte := evm.interpreter.intPool.get().SetInt64(int64(common.LeftPadBytes(val.Bytes(), 32)[th.Int64()]))
 		stack.push(byte)
 	} else {
 		stack.push(new(big.Int))
 	}
+
+	evm.interpreter.intPool.put(th, val)
 	return nil, nil
 }
-func opAddmod(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opAddmod(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y, z := stack.pop(), stack.pop(), stack.pop()
-	if z.Cmp(Zero) > 0 {
+	if z.Cmp(bigZero) > 0 {
 		add := x.Add(x, y)
 		add.Mod(add, z)
 		stack.push(U256(add))
 	} else {
 		stack.push(new(big.Int))
 	}
+
+	evm.interpreter.intPool.put(y, z)
 	return nil, nil
 }
-func opMulmod(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opMulmod(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	x, y, z := stack.pop(), stack.pop(), stack.pop()
-	if z.Cmp(Zero) > 0 {
+	if z.Cmp(bigZero) > 0 {
 		mul := x.Mul(x, y)
 		mul.Mod(mul, z)
 		stack.push(U256(mul))
 	} else {
 		stack.push(new(big.Int))
 	}
+
+	evm.interpreter.intPool.put(y, z)
 	return nil, nil
 }
 
-func opSha3(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opSha3(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	offset, size := stack.pop(), stack.pop()
 	data := memory.Get(offset.Int64(), size.Int64())
 	hash := crypto.Keccak256(data)
 
-	if env.vmConfig.EnablePreimageRecording {
-		env.StateDB.AddPreimage(common.BytesToHash(hash), data)
+	if evm.vmConfig.EnablePreimageRecording {
+		evm.StateDB.AddPreimage(common.BytesToHash(hash), data)
 	}
 
 	stack.push(common.BytesToBig(hash))
+
+	evm.interpreter.intPool.put(offset, size)
 	return nil, nil
 }
 
-func opAddress(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opAddress(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(common.Bytes2Big(contract.Address().Bytes()))
 	return nil, nil
 }
 
-func opBalance(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opBalance(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	addr := common.BigToAddress(stack.pop())
-	balance := env.StateDB.GetBalance(addr)
+	balance := evm.StateDB.GetBalance(addr)
 
 	stack.push(new(big.Int).Set(balance))
 	return nil, nil
 }
 
-func opOrigin(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(env.Origin.Big())
+func opOrigin(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(evm.Origin.Big())
 	return nil, nil
 }
 
-func opCaller(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opCaller(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	stack.push(contract.Caller().Big())
 	return nil, nil
 }
 
-func opCallValue(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(new(big.Int).Set(contract.value))
+func opCallValue(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(evm.interpreter.intPool.get().Set(contract.value))
 	return nil, nil
 }
 
-func opCalldataLoad(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opCalldataLoad(pc *uint64, evm *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(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(big.NewInt(int64(len(contract.Input))))
+func opCalldataSize(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(evm.interpreter.intPool.get().SetInt64(int64(len(contract.Input))))
 	return nil, nil
 }
 
-func opCalldataCopy(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opCalldataCopy(pc *uint64, evm *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))
+
+	evm.interpreter.intPool.put(mOff, cOff, l)
 	return nil, nil
 }
 
-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)
+func opExtCodeSize(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	a := stack.pop()
+
+	addr := common.BigToAddress(a)
+	a.SetInt64(int64(evm.StateDB.GetCodeSize(addr)))
+	stack.push(a)
+
 	return nil, nil
 }
 
-func opCodeSize(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	l := big.NewInt(int64(len(contract.Code)))
+func opCodeSize(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	l := evm.interpreter.intPool.get().SetInt64(int64(len(contract.Code)))
 	stack.push(l)
 	return nil, nil
 }
 
-func opCodeCopy(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opCodeCopy(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
 		mOff = stack.pop()
 		cOff = stack.pop()
@@ -328,113 +381,129 @@ func opCodeCopy(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack
 	codeCopy := getData(contract.Code, cOff, l)
 
 	memory.Set(mOff.Uint64(), l.Uint64(), codeCopy)
+
+	evm.interpreter.intPool.put(mOff, cOff, l)
 	return nil, nil
 }
 
-func opExtCodeCopy(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opExtCodeCopy(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
 		addr = common.BigToAddress(stack.pop())
 		mOff = stack.pop()
 		cOff = stack.pop()
 		l    = stack.pop()
 	)
-	codeCopy := getData(env.StateDB.GetCode(addr), cOff, l)
+	codeCopy := getData(evm.StateDB.GetCode(addr), cOff, l)
 
 	memory.Set(mOff.Uint64(), l.Uint64(), codeCopy)
+
+	evm.interpreter.intPool.put(mOff, cOff, l)
+
 	return nil, nil
 }
 
-func opGasprice(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(new(big.Int).Set(env.GasPrice))
+func opGasprice(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(evm.interpreter.intPool.get().Set(evm.GasPrice))
 	return nil, nil
 }
 
-func opBlockhash(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opBlockhash(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	num := stack.pop()
 
-	n := new(big.Int).Sub(env.BlockNumber, common.Big257)
-	if num.Cmp(n) > 0 && num.Cmp(env.BlockNumber) < 0 {
-		stack.push(env.GetHash(num.Uint64()).Big())
+	n := evm.interpreter.intPool.get().Sub(evm.BlockNumber, common.Big257)
+	if num.Cmp(n) > 0 && num.Cmp(evm.BlockNumber) < 0 {
+		stack.push(evm.GetHash(num.Uint64()).Big())
 	} else {
 		stack.push(new(big.Int))
 	}
+
+	evm.interpreter.intPool.put(num, n)
 	return nil, nil
 }
 
-func opCoinbase(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(env.Coinbase.Big())
+func opCoinbase(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(evm.Coinbase.Big())
 	return nil, nil
 }
 
-func opTimestamp(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(U256(new(big.Int).Set(env.Time)))
+func opTimestamp(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(U256(new(big.Int).Set(evm.Time)))
 	return nil, nil
 }
 
-func opNumber(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(U256(new(big.Int).Set(env.BlockNumber)))
+func opNumber(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(U256(new(big.Int).Set(evm.BlockNumber)))
 	return nil, nil
 }
 
-func opDifficulty(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(U256(new(big.Int).Set(env.Difficulty)))
+func opDifficulty(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(U256(new(big.Int).Set(evm.Difficulty)))
 	return nil, nil
 }
 
-func opGasLimit(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(U256(new(big.Int).Set(env.GasLimit)))
+func opGasLimit(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(U256(new(big.Int).Set(evm.GasLimit)))
 	return nil, nil
 }
 
-func opPop(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.pop()
+func opPop(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	evm.interpreter.intPool.put(stack.pop())
 	return nil, nil
 }
 
-func opMload(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opMload(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	offset := stack.pop()
 	val := common.BigD(memory.Get(offset.Int64(), 32))
 	stack.push(val)
+
+	evm.interpreter.intPool.put(offset)
 	return nil, nil
 }
 
-func opMstore(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opMstore(pc *uint64, evm *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))
+
+	evm.interpreter.intPool.put(mStart, val)
 	return nil, nil
 }
 
-func opMstore8(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opMstore8(pc *uint64, evm *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(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opSload(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	loc := common.BigToHash(stack.pop())
-	val := env.StateDB.GetState(contract.Address(), loc).Big()
+	val := evm.StateDB.GetState(contract.Address(), loc).Big()
 	stack.push(val)
 	return nil, nil
 }
 
-func opSstore(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opSstore(pc *uint64, evm *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))
+	evm.StateDB.SetState(contract.Address(), loc, common.BigToHash(val))
+
+	evm.interpreter.intPool.put(val)
 	return nil, nil
 }
 
-func opJump(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opJump(pc *uint64, evm *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()
+
+	evm.interpreter.intPool.put(pos)
 	return nil, nil
 }
-func opJumpi(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opJumpi(pc *uint64, evm *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) {
@@ -445,57 +514,62 @@ func opJumpi(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *St
 	} else {
 		*pc++
 	}
+
+	evm.interpreter.intPool.put(pos, cond)
 	return nil, nil
 }
-func opJumpdest(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opJumpdest(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	return nil, nil
 }
 
-func opPc(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(new(big.Int).SetUint64(*pc))
+func opPc(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(evm.interpreter.intPool.get().SetUint64(*pc))
 	return nil, nil
 }
 
-func opMsize(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(big.NewInt(int64(memory.Len())))
+func opMsize(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(evm.interpreter.intPool.get().SetInt64(int64(memory.Len())))
 	return nil, nil
 }
 
-func opGas(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	stack.push(new(big.Int).Set(contract.Gas))
+func opGas(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	stack.push(evm.interpreter.intPool.get().SetUint64(contract.Gas))
 	return nil, nil
 }
 
-func opCreate(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opCreate(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	var (
 		value        = stack.pop()
 		offset, size = stack.pop(), stack.pop()
 		input        = memory.Get(offset.Int64(), size.Int64())
-		gas          = new(big.Int).Set(contract.Gas)
+		gas          = contract.Gas
 	)
-	if env.ChainConfig().IsEIP150(env.BlockNumber) {
-		gas.Div(gas, n64)
-		gas = gas.Sub(contract.Gas, gas)
+	if evm.ChainConfig().IsEIP150(evm.BlockNumber) {
+		gas -= gas / 64
 	}
 
 	contract.UseGas(gas)
-	_, addr, suberr := env.Create(contract, input, gas, value)
+	_, addr, returnGas, suberr := evm.Create(contract, input, gas, value)
 	// Push item on the stack based on the returned error. If the ruleset is
 	// 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 == ErrCodeStoreOutOfGas {
+	if evm.ChainConfig().IsHomestead(evm.BlockNumber) && suberr == ErrCodeStoreOutOfGas {
 		stack.push(new(big.Int))
 	} else if suberr != nil && suberr != ErrCodeStoreOutOfGas {
 		stack.push(new(big.Int))
 	} else {
 		stack.push(addr.Big())
 	}
+	contract.Gas += returnGas
+
+	evm.interpreter.intPool.put(value, offset, size)
+
 	return nil, nil
 }
 
-func opCall(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	gas := stack.pop()
+func opCall(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	gas := stack.pop().Uint64()
 	// pop gas and value of the stack.
 	addr, value := stack.pop(), stack.pop()
 	value = U256(value)
@@ -509,25 +583,26 @@ func opCall(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Sta
 	// Get the arguments from the memory
 	args := memory.Get(inOffset.Int64(), inSize.Int64())
 
-	if len(value.Bytes()) > 0 {
-		gas.Add(gas, params.CallStipend)
+	if value.BitLen() > 0 {
+		gas += params.CallStipend
 	}
 
-	ret, err := env.Call(contract, address, args, gas, value)
-
+	ret, returnGas, err := evm.Call(contract, address, args, gas, value)
 	if err != nil {
 		stack.push(new(big.Int))
-
 	} else {
 		stack.push(big.NewInt(1))
 
 		memory.Set(retOffset.Uint64(), retSize.Uint64(), ret)
 	}
+	contract.Gas += returnGas
+
+	evm.interpreter.intPool.put(addr, value, inOffset, inSize, retOffset, retSize)
 	return nil, nil
 }
 
-func opCallCode(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
-	gas := stack.pop()
+func opCallCode(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	gas := stack.pop().Uint64()
 	// pop gas and value of the stack.
 	addr, value := stack.pop(), stack.pop()
 	value = U256(value)
@@ -541,12 +616,11 @@ func opCallCode(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack
 	// Get the arguments from the memory
 	args := memory.Get(inOffset.Int64(), inSize.Int64())
 
-	if len(value.Bytes()) > 0 {
-		gas.Add(gas, params.CallStipend)
+	if value.BitLen() > 0 {
+		gas += params.CallStipend
 	}
 
-	ret, err := env.CallCode(contract, address, args, gas, value)
-
+	ret, returnGas, err := evm.CallCode(contract, address, args, gas, value)
 	if err != nil {
 		stack.push(new(big.Int))
 
@@ -555,46 +629,54 @@ func opCallCode(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack
 
 		memory.Set(retOffset.Uint64(), retSize.Uint64(), ret)
 	}
+	contract.Gas += returnGas
+
+	evm.interpreter.intPool.put(addr, value, inOffset, inSize, retOffset, retSize)
 	return nil, nil
 }
 
-func opDelegateCall(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opDelegateCall(pc *uint64, evm *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) {
+	if !evm.ChainConfig().IsHomestead(evm.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()
+	gas, to, inOffset, inSize, outOffset, outSize := stack.pop().Uint64(), stack.pop(), stack.pop(), stack.pop(), stack.pop(), stack.pop()
 
 	toAddr := common.BigToAddress(to)
 	args := memory.Get(inOffset.Int64(), inSize.Int64())
-	ret, err := env.DelegateCall(contract, toAddr, args, gas)
+
+	ret, returnGas, err := evm.DelegateCall(contract, toAddr, args, gas)
 	if err != nil {
 		stack.push(new(big.Int))
 	} else {
 		stack.push(big.NewInt(1))
 		memory.Set(outOffset.Uint64(), outSize.Uint64(), ret)
 	}
+	contract.Gas += returnGas
+
+	evm.interpreter.intPool.put(to, inOffset, inSize, outOffset, outSize)
 	return nil, nil
 }
 
-func opReturn(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opReturn(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	offset, size := stack.pop(), stack.pop()
 	ret := memory.GetPtr(offset.Int64(), size.Int64())
 
+	evm.interpreter.intPool.put(offset, size)
 	return ret, nil
 }
 
-func opStop(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+func opStop(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	return nil, nil
 }
 
-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)
+func opSuicide(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	balance := evm.StateDB.GetBalance(contract.Address())
+	evm.StateDB.AddBalance(common.BigToAddress(stack.pop()), balance)
 
-	env.StateDB.Suicide(contract.Address())
+	evm.StateDB.Suicide(contract.Address())
 
 	return nil, nil
 }
@@ -603,7 +685,7 @@ func opSuicide(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *
 
 // make log instruction function
 func makeLog(size int) executionFunc {
-	return func(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	return func(pc *uint64, evm *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++ {
@@ -611,22 +693,24 @@ func makeLog(size int) executionFunc {
 		}
 
 		d := memory.Get(mStart.Int64(), mSize.Int64())
-		env.StateDB.AddLog(&types.Log{
+		evm.StateDB.AddLog(&types.Log{
 			Address: contract.Address(),
 			Topics:  topics,
 			Data:    d,
 			// This is a non-consensus field, but assigned here because
 			// core/state doesn't know the current block number.
-			BlockNumber: env.BlockNumber.Uint64(),
+			BlockNumber: evm.BlockNumber.Uint64(),
 		})
+
+		evm.interpreter.intPool.put(mStart, mSize)
 		return nil, nil
 	}
 }
 
 // make push instruction function
 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)
+	return func(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+		byts := getData(contract.Code, evm.interpreter.intPool.get().SetUint64(*pc+1), bsize)
 		stack.push(common.Bytes2Big(byts))
 		*pc += size
 		return nil, nil
@@ -635,7 +719,7 @@ func makePush(size uint64, bsize *big.Int) executionFunc {
 
 // make push instruction function
 func makeDup(size int64) executionFunc {
-	return func(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	return func(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 		stack.dup(int(size))
 		return nil, nil
 	}
@@ -645,7 +729,7 @@ func makeDup(size int64) executionFunc {
 func makeSwap(size int64) executionFunc {
 	// switch n + 1 otherwise n would be swapped with n
 	size += 1
-	return func(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	return func(pc *uint64, evm *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 		stack.swap(int(size))
 		return nil, nil
 	}
diff --git a/core/vm/int_pool_verifier.go b/core/vm/int_pool_verifier.go
new file mode 100644
index 000000000..61c83ba7e
--- /dev/null
+++ b/core/vm/int_pool_verifier.go
@@ -0,0 +1,15 @@
+// +build VERIFY_EVM_INTEGER_POOL
+
+package vm
+
+import "fmt"
+
+const verifyPool = true
+
+func verifyIntegerPool(ip *intPool) {
+	for i, item := range ip.pool.data {
+		if item.Cmp(checkVal) != 0 {
+			panic(fmt.Sprintf("%d'th item failed aggressive pool check. Value was modified", i))
+		}
+	}
+}
diff --git a/core/vm/int_pool_verifier_empty.go b/core/vm/int_pool_verifier_empty.go
new file mode 100644
index 000000000..982f8c6dd
--- /dev/null
+++ b/core/vm/int_pool_verifier_empty.go
@@ -0,0 +1,7 @@
+// +build !VERIFY_EVM_INTEGER_POOL
+
+package vm
+
+const verifyPool = false
+
+func verifyIntegerPool(ip *intPool) {}
diff --git a/core/vm/vm.go b/core/vm/interpreter.go
index 05886a863..46c6befef 100644
--- a/core/vm/vm.go
+++ b/core/vm/interpreter.go
@@ -23,6 +23,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/math"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
@@ -60,6 +61,7 @@ type Interpreter struct {
 	env      *EVM
 	cfg      Config
 	gasTable params.GasTable
+	intPool  *intPool
 }
 
 // NewInterpreter returns a new instance of the Interpreter.
@@ -75,6 +77,7 @@ func NewInterpreter(env *EVM, cfg Config) *Interpreter {
 		env:      env,
 		cfg:      cfg,
 		gasTable: env.ChainConfig().GasTable(env.BlockNumber),
+		intPool:  newIntPool(),
 	}
 }
 
@@ -106,14 +109,18 @@ func (evm *Interpreter) Run(contract *Contract, input []byte) (ret []byte, err e
 		// For optimisation reason we're using uint64 as the program counter.
 		// It's theoretically possible to go above 2^64. The YP defines the PC to be uint256. Practically much less so feasible.
 		pc   = uint64(0) // program counter
-		cost *big.Int
+		cost uint64
 	)
 	contract.Input = input
 
 	// User defer pattern to check for an error and, based on the error being nil or not, use all gas and return.
 	defer func() {
 		if err != nil && evm.cfg.Debug {
-			evm.cfg.Tracer.CaptureState(evm.env, pc, op, contract.Gas, cost, mem, stack, contract, evm.env.depth, err)
+			// XXX For debugging
+			//fmt.Printf("%04d: %8v    cost = %-8d stack = %-8d ERR = %v\n", pc, op, cost, stack.len(), err)
+			// TODO update the tracer
+			g, c := new(big.Int).SetUint64(contract.Gas), new(big.Int).SetUint64(cost)
+			evm.cfg.Tracer.CaptureState(evm.env, pc, op, g, c, mem, stack, contract, evm.env.depth, err)
 		}
 	}()
 
@@ -147,34 +154,47 @@ func (evm *Interpreter) Run(contract *Contract, input []byte) (ret []byte, err e
 			return nil, err
 		}
 
-		var memorySize *big.Int
+		var memorySize uint64
 		// calculate the new memory size and expand the memory to fit
 		// the operation
 		if operation.memorySize != nil {
-			memorySize = operation.memorySize(stack)
+			memSize, overflow := bigUint64(operation.memorySize(stack))
+			if overflow {
+				return nil, errGasUintOverflow
+			}
 			// memory is expanded in words of 32 bytes. Gas
 			// is also calculated in words.
-			memorySize.Mul(toWordSize(memorySize), big.NewInt(32))
+			if memorySize, overflow = math.SafeMul(toWordSize(memSize), 32); overflow {
+				return nil, errGasUintOverflow
+			}
 		}
 
 		if !evm.cfg.DisableGasMetering {
 			// consume the gas and return an error if not enough gas is available.
 			// cost is explicitly set so that the capture state defer method cas get the proper cost
-			cost = operation.gasCost(evm.gasTable, evm.env, contract, stack, mem, memorySize)
-			if !contract.UseGas(cost) {
+			cost, err = operation.gasCost(evm.gasTable, evm.env, contract, stack, mem, memorySize)
+			if err != nil || !contract.UseGas(cost) {
 				return nil, ErrOutOfGas
 			}
 		}
-		if memorySize != nil {
-			mem.Resize(memorySize.Uint64())
+		if memorySize > 0 {
+			mem.Resize(memorySize)
 		}
 
 		if evm.cfg.Debug {
-			evm.cfg.Tracer.CaptureState(evm.env, pc, op, contract.Gas, cost, mem, stack, contract, evm.env.depth, err)
+			g, c := new(big.Int).SetUint64(contract.Gas), new(big.Int).SetUint64(cost)
+			evm.cfg.Tracer.CaptureState(evm.env, pc, op, g, c, mem, stack, contract, evm.env.depth, err)
 		}
+		// XXX For debugging
+		//fmt.Printf("%04d: %8v    cost = %-8d stack = %-8d\n", pc, op, cost, stack.len())
 
 		// execute the operation
 		res, err := operation.execute(&pc, evm.env, contract, mem, stack)
+		// verifyPool is a build flag. Pool verification makes sure the integrity
+		// of the integer pool by comparing values to a default value.
+		if verifyPool {
+			verifyIntegerPool(evm.intPool)
+		}
 		switch {
 		case err != nil:
 			return nil, err
diff --git a/core/vm/virtual_machine.go b/core/vm/intpool.go
index 629108884..4f1228e14 100644
--- a/core/vm/virtual_machine.go
+++ b/core/vm/intpool.go
@@ -1,4 +1,4 @@
-// Copyright 2014 The go-ethereum Authors
+// Copyright 2017 The go-ethereum Authors
 // This file is part of the go-ethereum library.
 //
 // The go-ethereum library is free software: you can redistribute it and/or modify
@@ -16,7 +16,34 @@
 
 package vm
 
-// VirtualMachine is an EVM interface
-type VirtualMachine interface {
-	Run(*Contract, []byte) ([]byte, error)
+import "math/big"
+
+var checkVal = big.NewInt(-42)
+
+// intPool is a pool of big integers that
+// can be reused for all big.Int operations.
+type intPool struct {
+	pool *Stack
+}
+
+func newIntPool() *intPool {
+	return &intPool{pool: newstack()}
+}
+
+func (p *intPool) get() *big.Int {
+	if p.pool.len() > 0 {
+		return p.pool.pop()
+	}
+	return new(big.Int)
+}
+func (p *intPool) put(is ...*big.Int) {
+	for _, i := range is {
+		// verifyPool is a build flag. Pool verification makes sure the integrity
+		// of the integer pool by comparing values to a default value.
+		if verifyPool {
+			i.Set(checkVal)
+		}
+
+		p.pool.push(i)
+	}
 }
diff --git a/core/vm/jump_table.go b/core/vm/jump_table.go
index 073798274..ed30100ac 100644
--- a/core/vm/jump_table.go
+++ b/core/vm/jump_table.go
@@ -17,6 +17,7 @@
 package vm
 
 import (
+	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/params"
@@ -24,11 +25,13 @@ import (
 
 type (
 	executionFunc       func(pc *uint64, env *EVM, contract *Contract, memory *Memory, stack *Stack) ([]byte, error)
-	gasFunc             func(params.GasTable, *EVM, *Contract, *Stack, *Memory, *big.Int) *big.Int
+	gasFunc             func(params.GasTable, *EVM, *Contract, *Stack, *Memory, uint64) (uint64, error) // last parameter is the requested memory size as a uint64
 	stackValidationFunc func(*Stack) error
 	memorySizeFunc      func(*Stack) *big.Int
 )
 
+var errGasUintOverflow = errors.New("gas uint64 overflow")
+
 type operation struct {
 	// op is the operation function
 	execute executionFunc
@@ -54,7 +57,7 @@ func NewJumpTable() [256]operation {
 	return [256]operation{
 		STOP: {
 			execute:       opStop,
-			gasCost:       constGasFunc(new(big.Int)),
+			gasCost:       constGasFunc(0),
 			validateStack: makeStackFunc(0, 0),
 			halts:         true,
 			valid:         true,
@@ -62,139 +65,139 @@ func NewJumpTable() [256]operation {
 		ADD: {
 			execute:       opAdd,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		MUL: {
 			execute:       opMul,
 			gasCost:       constGasFunc(GasFastStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		SUB: {
 			execute:       opSub,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		DIV: {
 			execute:       opDiv,
 			gasCost:       constGasFunc(GasFastStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		SDIV: {
 			execute:       opSdiv,
 			gasCost:       constGasFunc(GasFastStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		MOD: {
 			execute:       opMod,
 			gasCost:       constGasFunc(GasFastStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		SMOD: {
 			execute:       opSmod,
 			gasCost:       constGasFunc(GasFastStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		ADDMOD: {
 			execute:       opAddmod,
 			gasCost:       constGasFunc(GasMidStep),
-			validateStack: makeStackFunc(3, -2),
+			validateStack: makeStackFunc(3, 1),
 			valid:         true,
 		},
 		MULMOD: {
 			execute:       opMulmod,
 			gasCost:       constGasFunc(GasMidStep),
-			validateStack: makeStackFunc(3, -2),
+			validateStack: makeStackFunc(3, 1),
 			valid:         true,
 		},
 		EXP: {
 			execute:       opExp,
 			gasCost:       gasExp,
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		SIGNEXTEND: {
 			execute:       opSignExtend,
 			gasCost:       constGasFunc(GasFastStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		LT: {
 			execute:       opLt,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		GT: {
 			execute:       opGt,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		SLT: {
 			execute:       opSlt,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		SGT: {
 			execute:       opSgt,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		EQ: {
 			execute:       opEq,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		ISZERO: {
 			execute:       opIszero,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(1, 0),
+			validateStack: makeStackFunc(1, 1),
 			valid:         true,
 		},
 		AND: {
 			execute:       opAnd,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		XOR: {
 			execute:       opXor,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		OR: {
 			execute:       opOr,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		NOT: {
 			execute:       opNot,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(1, 0),
+			validateStack: makeStackFunc(1, 1),
 			valid:         true,
 		},
 		BYTE: {
 			execute:       opByte,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			valid:         true,
 		},
 		SHA3: {
 			execute:       opSha3,
 			gasCost:       gasSha3,
-			validateStack: makeStackFunc(2, -1),
+			validateStack: makeStackFunc(2, 1),
 			memorySize:    memorySha3,
 			valid:         true,
 		},
@@ -207,7 +210,7 @@ func NewJumpTable() [256]operation {
 		BALANCE: {
 			execute:       opBalance,
 			gasCost:       gasBalance,
-			validateStack: makeStackFunc(1, 0),
+			validateStack: makeStackFunc(1, 1),
 			valid:         true,
 		},
 		ORIGIN: {
@@ -231,7 +234,7 @@ func NewJumpTable() [256]operation {
 		CALLDATALOAD: {
 			execute:       opCalldataLoad,
 			gasCost:       constGasFunc(GasFastestStep),
-			validateStack: makeStackFunc(1, 0),
+			validateStack: makeStackFunc(1, 1),
 			valid:         true,
 		},
 		CALLDATASIZE: {
@@ -243,7 +246,7 @@ func NewJumpTable() [256]operation {
 		CALLDATACOPY: {
 			execute:       opCalldataCopy,
 			gasCost:       gasCalldataCopy,
-			validateStack: makeStackFunc(3, -3),
+			validateStack: makeStackFunc(3, 0),
 			memorySize:    memoryCalldataCopy,
 			valid:         true,
 		},
@@ -256,7 +259,7 @@ func NewJumpTable() [256]operation {
 		CODECOPY: {
 			execute:       opCodeCopy,
 			gasCost:       gasCodeCopy,
-			validateStack: makeStackFunc(3, -3),
+			validateStack: makeStackFunc(3, 0),
 			memorySize:    memoryCodeCopy,
 			valid:         true,
 		},
@@ -269,20 +272,20 @@ func NewJumpTable() [256]operation {
 		EXTCODESIZE: {
 			execute:       opExtCodeSize,
 			gasCost:       gasExtCodeSize,
-			validateStack: makeStackFunc(1, 0),
+			validateStack: makeStackFunc(1, 1),
 			valid:         true,
 		},
 		EXTCODECOPY: {
 			execute:       opExtCodeCopy,
 			gasCost:       gasExtCodeCopy,
-			validateStack: makeStackFunc(4, -4),
+			validateStack: makeStackFunc(4, 0),
 			memorySize:    memoryExtCodeCopy,
 			valid:         true,
 		},
 		BLOCKHASH: {
 			execute:       opBlockhash,
 			gasCost:       constGasFunc(GasExtStep),
-			validateStack: makeStackFunc(1, 0),
+			validateStack: makeStackFunc(1, 1),
 			valid:         true,
 		},
 		COINBASE: {
@@ -318,20 +321,20 @@ func NewJumpTable() [256]operation {
 		POP: {
 			execute:       opPop,
 			gasCost:       constGasFunc(GasQuickStep),
-			validateStack: makeStackFunc(1, -1),
+			validateStack: makeStackFunc(1, 0),
 			valid:         true,
 		},
 		MLOAD: {
 			execute:       opMload,
 			gasCost:       gasMLoad,
-			validateStack: makeStackFunc(1, 0),
+			validateStack: makeStackFunc(1, 1),
 			memorySize:    memoryMLoad,
 			valid:         true,
 		},
 		MSTORE: {
 			execute:       opMstore,
 			gasCost:       gasMStore,
-			validateStack: makeStackFunc(2, -2),
+			validateStack: makeStackFunc(2, 0),
 			memorySize:    memoryMStore,
 			valid:         true,
 		},
@@ -339,33 +342,33 @@ func NewJumpTable() [256]operation {
 			execute:       opMstore8,
 			gasCost:       gasMStore8,
 			memorySize:    memoryMStore8,
-			validateStack: makeStackFunc(2, -2),
+			validateStack: makeStackFunc(2, 0),
 
 			valid: true,
 		},
 		SLOAD: {
 			execute:       opSload,
 			gasCost:       gasSLoad,
-			validateStack: makeStackFunc(1, 0),
+			validateStack: makeStackFunc(1, 1),
 			valid:         true,
 		},
 		SSTORE: {
 			execute:       opSstore,
 			gasCost:       gasSStore,
-			validateStack: makeStackFunc(2, -2),
+			validateStack: makeStackFunc(2, 0),
 			valid:         true,
 		},
 		JUMP: {
 			execute:       opJump,
 			gasCost:       constGasFunc(GasMidStep),
-			validateStack: makeStackFunc(1, -1),
+			validateStack: makeStackFunc(1, 0),
 			jumps:         true,
 			valid:         true,
 		},
 		JUMPI: {
 			execute:       opJumpi,
 			gasCost:       constGasFunc(GasSlowStep),
-			validateStack: makeStackFunc(2, -2),
+			validateStack: makeStackFunc(2, 0),
 			jumps:         true,
 			valid:         true,
 		},
@@ -780,63 +783,63 @@ func NewJumpTable() [256]operation {
 		LOG0: {
 			execute:       makeLog(0),
 			gasCost:       makeGasLog(0),
-			validateStack: makeStackFunc(2, -2),
+			validateStack: makeStackFunc(2, 0),
 			memorySize:    memoryLog,
 			valid:         true,
 		},
 		LOG1: {
 			execute:       makeLog(1),
 			gasCost:       makeGasLog(1),
-			validateStack: makeStackFunc(3, -3),
+			validateStack: makeStackFunc(3, 0),
 			memorySize:    memoryLog,
 			valid:         true,
 		},
 		LOG2: {
 			execute:       makeLog(2),
 			gasCost:       makeGasLog(2),
-			validateStack: makeStackFunc(4, -4),
+			validateStack: makeStackFunc(4, 0),
 			memorySize:    memoryLog,
 			valid:         true,
 		},
 		LOG3: {
 			execute:       makeLog(3),
 			gasCost:       makeGasLog(3),
-			validateStack: makeStackFunc(5, -5),
+			validateStack: makeStackFunc(5, 0),
 			memorySize:    memoryLog,
 			valid:         true,
 		},
 		LOG4: {
 			execute:       makeLog(4),
 			gasCost:       makeGasLog(4),
-			validateStack: makeStackFunc(6, -6),
+			validateStack: makeStackFunc(6, 0),
 			memorySize:    memoryLog,
 			valid:         true,
 		},
 		CREATE: {
 			execute:       opCreate,
 			gasCost:       gasCreate,
-			validateStack: makeStackFunc(3, -2),
+			validateStack: makeStackFunc(3, 1),
 			memorySize:    memoryCreate,
 			valid:         true,
 		},
 		CALL: {
 			execute:       opCall,
 			gasCost:       gasCall,
-			validateStack: makeStackFunc(7, -6),
+			validateStack: makeStackFunc(7, 1),
 			memorySize:    memoryCall,
 			valid:         true,
 		},
 		CALLCODE: {
 			execute:       opCallCode,
 			gasCost:       gasCallCode,
-			validateStack: makeStackFunc(7, -6),
+			validateStack: makeStackFunc(7, 1),
 			memorySize:    memoryCall,
 			valid:         true,
 		},
 		RETURN: {
 			execute:       opReturn,
 			gasCost:       gasReturn,
-			validateStack: makeStackFunc(2, -2),
+			validateStack: makeStackFunc(2, 0),
 			memorySize:    memoryReturn,
 			halts:         true,
 			valid:         true,
@@ -844,14 +847,14 @@ func NewJumpTable() [256]operation {
 		DELEGATECALL: {
 			execute:       opDelegateCall,
 			gasCost:       gasDelegateCall,
-			validateStack: makeStackFunc(6, -5),
+			validateStack: makeStackFunc(6, 1),
 			memorySize:    memoryDelegateCall,
 			valid:         true,
 		},
 		SELFDESTRUCT: {
 			execute:       opSuicide,
 			gasCost:       gasSuicide,
-			validateStack: makeStackFunc(1, -1),
+			validateStack: makeStackFunc(1, 0),
 			halts:         true,
 			valid:         true,
 		},
diff --git a/core/vm/logger_test.go b/core/vm/logger_test.go
index 1d0bd96fa..ca60cba43 100644
--- a/core/vm/logger_test.go
+++ b/core/vm/logger_test.go
@@ -56,7 +56,7 @@ func TestStoreCapture(t *testing.T) {
 		logger   = NewStructLogger(nil)
 		mem      = NewMemory()
 		stack    = newstack()
-		contract = NewContract(&dummyContractRef{}, &dummyContractRef{}, new(big.Int), new(big.Int))
+		contract = NewContract(&dummyContractRef{}, &dummyContractRef{}, new(big.Int), 0)
 	)
 	stack.push(big.NewInt(1))
 	stack.push(big.NewInt(0))
@@ -78,7 +78,7 @@ func TestStorageCapture(t *testing.T) {
 	t.Skip("implementing this function is difficult. it requires all sort of interfaces to be implemented which isn't trivial. The value (the actual test) isn't worth it")
 	var (
 		ref      = &dummyContractRef{}
-		contract = NewContract(ref, ref, new(big.Int), new(big.Int))
+		contract = NewContract(ref, ref, new(big.Int), 0)
 		env      = NewEVM(Context{}, dummyStateDB{ref: ref}, params.TestChainConfig, Config{EnableJit: false, ForceJit: false})
 		logger   = NewStructLogger(nil)
 		mem      = NewMemory()
diff --git a/core/vm/memory.go b/core/vm/memory.go
index d01188417..99a84d227 100644
--- a/core/vm/memory.go
+++ b/core/vm/memory.go
@@ -20,11 +20,12 @@ import "fmt"
 
 // Memory implements a simple memory model for the ethereum virtual machine.
 type Memory struct {
-	store []byte
+	store       []byte
+	lastGasCost uint64
 }
 
 func NewMemory() *Memory {
-	return &Memory{nil}
+	return &Memory{}
 }
 
 // Set sets offset + size to value
diff --git a/core/vm/runtime/env.go b/core/vm/runtime/env.go
index a25c6d71c..9aa88e669 100644
--- a/core/vm/runtime/env.go
+++ b/core/vm/runtime/env.go
@@ -36,7 +36,7 @@ func NewEnv(cfg *Config, state *state.StateDB) *vm.EVM {
 		BlockNumber: cfg.BlockNumber,
 		Time:        cfg.Time,
 		Difficulty:  cfg.Difficulty,
-		GasLimit:    cfg.GasLimit,
+		GasLimit:    new(big.Int).SetUint64(cfg.GasLimit),
 		GasPrice:    new(big.Int),
 	}
 
diff --git a/core/vm/runtime/runtime.go b/core/vm/runtime/runtime.go
index b5adb982c..cf46603db 100644
--- a/core/vm/runtime/runtime.go
+++ b/core/vm/runtime/runtime.go
@@ -17,6 +17,7 @@
 package runtime
 
 import (
+	"math"
 	"math/big"
 	"time"
 
@@ -37,7 +38,7 @@ type Config struct {
 	Coinbase    common.Address
 	BlockNumber *big.Int
 	Time        *big.Int
-	GasLimit    *big.Int
+	GasLimit    uint64
 	GasPrice    *big.Int
 	Value       *big.Int
 	DisableJit  bool // "disable" so it's enabled by default
@@ -68,8 +69,8 @@ func setDefaults(cfg *Config) {
 	if cfg.Time == nil {
 		cfg.Time = big.NewInt(time.Now().Unix())
 	}
-	if cfg.GasLimit == nil {
-		cfg.GasLimit = new(big.Int).Set(common.MaxBig)
+	if cfg.GasLimit == 0 {
+		cfg.GasLimit = math.MaxUint64
 	}
 	if cfg.GasPrice == nil {
 		cfg.GasPrice = new(big.Int)
@@ -112,7 +113,7 @@ func Execute(code, input []byte, cfg *Config) ([]byte, *state.StateDB, error) {
 	receiver.SetCode(crypto.Keccak256Hash(code), code)
 
 	// Call the code with the given configuration.
-	ret, err := vmenv.Call(
+	ret, _, err := vmenv.Call(
 		sender,
 		receiver.Address(),
 		input,
@@ -140,12 +141,13 @@ func Create(input []byte, cfg *Config) ([]byte, common.Address, error) {
 	)
 
 	// Call the code with the given configuration.
-	return vmenv.Create(
+	code, address, _, err := vmenv.Create(
 		sender,
 		input,
 		cfg.GasLimit,
 		cfg.Value,
 	)
+	return code, address, err
 }
 
 // Call executes the code given by the contract's address. It will return the
@@ -160,7 +162,7 @@ func Call(address common.Address, input []byte, cfg *Config) ([]byte, error) {
 
 	sender := cfg.State.GetOrNewStateObject(cfg.Origin)
 	// Call the code with the given configuration.
-	ret, err := vmenv.Call(
+	ret, _, err := vmenv.Call(
 		sender,
 		address,
 		input,
diff --git a/core/vm/runtime/runtime_test.go b/core/vm/runtime/runtime_test.go
index 1e618b688..8ad74a89a 100644
--- a/core/vm/runtime/runtime_test.go
+++ b/core/vm/runtime/runtime_test.go
@@ -39,8 +39,8 @@ func TestDefaults(t *testing.T) {
 	if cfg.Time == nil {
 		t.Error("expected time to be non nil")
 	}
-	if cfg.GasLimit == nil {
-		t.Error("expected time to be non nil")
+	if cfg.GasLimit == 0 {
+		t.Error("didn't expect gaslimit to be zero")
 	}
 	if cfg.GasPrice == nil {
 		t.Error("expected time to be non nil")
diff --git a/core/vm/stack_table.go b/core/vm/stack_table.go
index eed8805f2..ddc41fed2 100644
--- a/core/vm/stack_table.go
+++ b/core/vm/stack_table.go
@@ -6,13 +6,13 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
-func makeStackFunc(pop, diff int) stackValidationFunc {
+func makeStackFunc(pop, push int) stackValidationFunc {
 	return func(stack *Stack) error {
 		if err := stack.require(pop); err != nil {
 			return err
 		}
 
-		if int64(stack.len()+diff) > params.StackLimit.Int64() {
+		if stack.len()+push-pop > int(params.StackLimit) {
 			return fmt.Errorf("stack limit reached %d (%d)", stack.len(), params.StackLimit)
 		}
 		return nil
@@ -20,9 +20,9 @@ func makeStackFunc(pop, diff int) stackValidationFunc {
 }
 
 func makeDupStackFunc(n int) stackValidationFunc {
-	return makeStackFunc(n, 1)
+	return makeStackFunc(n, n+1)
 }
 
 func makeSwapStackFunc(n int) stackValidationFunc {
-	return makeStackFunc(n, 0)
+	return makeStackFunc(n, n)
 }