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, 21 insertions, 18 deletions

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