params, core/vm: Istanbul EIP-1108 bn256 gas cost reduction (#19904)

* params: add IsIstanbul to config + rules

IstanbulBlock, used to determine if the config IsIstanbul, is currently
left nil until an actual block is chosen.

* params, core/vm: implement EIP-1108

Old gas costs for elliptic curve operations are given the PreIstanbul
prefix, while current gas costs retain the unprefixed names. The actual
precompile implementations are the same, so they are factored out into
common functions that are called by the pre-Istanbul and current
precompile structs. Finally, an Istanbul precompile list is added that
references the new precompile structs, which in turn reference the new
gas costs.

* params: fix fork ordering, add missing chain compatibility check

1 files changed, 99 insertions, 26 deletions

diff --git a/core/vm/contracts.go b/core/vm/contracts.go
index 20b741f8f..0e4fe0198 100644
--- a/core/vm/contracts.go
+++ b/core/vm/contracts.go
@@ -54,9 +54,22 @@ var PrecompiledContractsByzantium = map[common.Address]PrecompiledContract{
 	common.BytesToAddress([]byte{3}): &ripemd160hash{},
 	common.BytesToAddress([]byte{4}): &dataCopy{},
 	common.BytesToAddress([]byte{5}): &bigModExp{},
-	common.BytesToAddress([]byte{6}): &bn256Add{},
-	common.BytesToAddress([]byte{7}): &bn256ScalarMul{},
-	common.BytesToAddress([]byte{8}): &bn256Pairing{},
+	common.BytesToAddress([]byte{6}): &bn256AddByzantium{},
+	common.BytesToAddress([]byte{7}): &bn256ScalarMulByzantium{},
+	common.BytesToAddress([]byte{8}): &bn256PairingByzantium{},
+}
+
+// PrecompiledContractsIstanbul contains the default set of pre-compiled Ethereum
+// contracts used in the Istanbul release.
+var PrecompiledContractsIstanbul = map[common.Address]PrecompiledContract{
+	common.BytesToAddress([]byte{1}): &ecrecover{},
+	common.BytesToAddress([]byte{2}): &sha256hash{},
+	common.BytesToAddress([]byte{3}): &ripemd160hash{},
+	common.BytesToAddress([]byte{4}): &dataCopy{},
+	common.BytesToAddress([]byte{5}): &bigModExp{},
+	common.BytesToAddress([]byte{6}): &bn256AddIstanbul{},
+	common.BytesToAddress([]byte{7}): &bn256ScalarMulIstanbul{},
+	common.BytesToAddress([]byte{8}): &bn256PairingIstanbul{},
 }
 
 // RunPrecompiledContract runs and evaluates the output of a precompiled contract.
@@ -271,15 +284,9 @@ func newTwistPoint(blob []byte) (*bn256.G2, error) {
 	return p, nil
 }
 
-// bn256Add implements a native elliptic curve point addition.
-type bn256Add struct{}
-
-// RequiredGas returns the gas required to execute the pre-compiled contract.
-func (c *bn256Add) RequiredGas(input []byte) uint64 {
-	return params.Bn256AddGas
-}
-
-func (c *bn256Add) Run(input []byte) ([]byte, error) {
+// runBn256Add implements the Bn256Add precompile, referenced by both
+// Byzantium and Istanbul operations.
+func runBn256Add(input []byte) ([]byte, error) {
 	x, err := newCurvePoint(getData(input, 0, 64))
 	if err != nil {
 		return nil, err
@@ -293,15 +300,35 @@ func (c *bn256Add) Run(input []byte) ([]byte, error) {
 	return res.Marshal(), nil
 }
 
-// bn256ScalarMul implements a native elliptic curve scalar multiplication.
-type bn256ScalarMul struct{}
+// bn256Add implements a native elliptic curve point addition conforming to
+// Istanbul consensus rules.
+type bn256AddIstanbul struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256AddIstanbul) RequiredGas(input []byte) uint64 {
+	return params.Bn256AddGasIstanbul
+}
+
+func (c *bn256AddIstanbul) Run(input []byte) ([]byte, error) {
+	return runBn256Add(input)
+}
+
+// bn256AddByzantium implements a native elliptic curve point addition
+// conforming to Byzantium consensus rules.
+type bn256AddByzantium struct{}
 
 // RequiredGas returns the gas required to execute the pre-compiled contract.
-func (c *bn256ScalarMul) RequiredGas(input []byte) uint64 {
-	return params.Bn256ScalarMulGas
+func (c *bn256AddByzantium) RequiredGas(input []byte) uint64 {
+	return params.Bn256AddGasByzantium
+}
+
+func (c *bn256AddByzantium) Run(input []byte) ([]byte, error) {
+	return runBn256Add(input)
 }
 
-func (c *bn256ScalarMul) Run(input []byte) ([]byte, error) {
+// runBn256ScalarMul implements the Bn256ScalarMul precompile, referenced by
+// both Byzantium and Istanbul operations.
+func runBn256ScalarMul(input []byte) ([]byte, error) {
 	p, err := newCurvePoint(getData(input, 0, 64))
 	if err != nil {
 		return nil, err
@@ -311,6 +338,32 @@ func (c *bn256ScalarMul) Run(input []byte) ([]byte, error) {
 	return res.Marshal(), nil
 }
 
+// bn256ScalarMulIstanbul implements a native elliptic curve scalar
+// multiplication conforming to Istanbul consensus rules.
+type bn256ScalarMulIstanbul struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256ScalarMulIstanbul) RequiredGas(input []byte) uint64 {
+	return params.Bn256ScalarMulGasIstanbul
+}
+
+func (c *bn256ScalarMulIstanbul) Run(input []byte) ([]byte, error) {
+	return runBn256ScalarMul(input)
+}
+
+// bn256ScalarMulByzantium implements a native elliptic curve scalar
+// multiplication conforming to Byzantium consensus rules.
+type bn256ScalarMulByzantium struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256ScalarMulByzantium) RequiredGas(input []byte) uint64 {
+	return params.Bn256ScalarMulGasByzantium
+}
+
+func (c *bn256ScalarMulByzantium) Run(input []byte) ([]byte, error) {
+	return runBn256ScalarMul(input)
+}
+
 var (
 	// true32Byte is returned if the bn256 pairing check succeeds.
 	true32Byte = []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}
@@ -322,15 +375,9 @@ var (
 	errBadPairingInput = errors.New("bad elliptic curve pairing size")
 )
 
-// bn256Pairing implements a pairing pre-compile for the bn256 curve
-type bn256Pairing struct{}
-
-// RequiredGas returns the gas required to execute the pre-compiled contract.
-func (c *bn256Pairing) RequiredGas(input []byte) uint64 {
-	return params.Bn256PairingBaseGas + uint64(len(input)/192)*params.Bn256PairingPerPointGas
-}
-
-func (c *bn256Pairing) Run(input []byte) ([]byte, error) {
+// runBn256Pairing implements the Bn256Pairing precompile, referenced by both
+// Byzantium and Istanbul operations.
+func runBn256Pairing(input []byte) ([]byte, error) {
 	// Handle some corner cases cheaply
 	if len(input)%192 > 0 {
 		return nil, errBadPairingInput
@@ -358,3 +405,29 @@ func (c *bn256Pairing) Run(input []byte) ([]byte, error) {
 	}
 	return false32Byte, nil
 }
+
+// bn256PairingIstanbul implements a pairing pre-compile for the bn256 curve
+// conforming to Istanbul consensus rules.
+type bn256PairingIstanbul struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256PairingIstanbul) RequiredGas(input []byte) uint64 {
+	return params.Bn256PairingBaseGasIstanbul + uint64(len(input)/192)*params.Bn256PairingPerPointGasIstanbul
+}
+
+func (c *bn256PairingIstanbul) Run(input []byte) ([]byte, error) {
+	return runBn256Pairing(input)
+}
+
+// bn256PairingByzantium implements a pairing pre-compile for the bn256 curve
+// conforming to Byzantium consensus rules.
+type bn256PairingByzantium struct{}
+
+// RequiredGas returns the gas required to execute the pre-compiled contract.
+func (c *bn256PairingByzantium) RequiredGas(input []byte) uint64 {
+	return params.Bn256PairingBaseGasByzantium + uint64(len(input)/192)*params.Bn256PairingPerPointGasByzantium
+}
+
+func (c *bn256PairingByzantium) Run(input []byte) ([]byte, error) {
+	return runBn256Pairing(input)
+}