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

1 files changed, 23 insertions, 130 deletions

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
 }