core, params: implement EIP-1087, net storage gas metering

accounts/abi/bind/backends/simulated.go

@@ -154,7 +154,7 @@ func (b *SimulatedBackend) StorageAt(ctx context.Context, contract common.Addres
 		return nil, errBlockNumberUnsupported
 	}
 	statedb, _ := b.blockchain.State()
-	val := statedb.GetState(contract, key)
+	val, _ := statedb.GetState(contract, key)
 	return val[:], nil
 }
 

core/state/journal.go

@@ -108,8 +108,10 @@ type (
 		prev    uint64
 	}
 	storageChange struct {
-		account       *common.Address
+		account   *common.Address
-		key, prevalue common.Hash
+		key       common.Hash
+		prevValue common.Hash
+		prevDirty bool
 	}
 	codeChange struct {
 		account            *common.Address
@@ -196,7 +198,7 @@ func (ch codeChange) dirtied() *common.Address {
 }
 
 func (ch storageChange) revert(s *StateDB) {
-	s.getStateObject(*ch.account).setState(ch.key, ch.prevalue)
+	s.getStateObject(*ch.account).setState(ch.key, ch.prevValue, ch.prevDirty)
 }
 
 func (ch storageChange) dirtied() *common.Address {

core/state/state_object.go

@@ -78,7 +78,6 @@ type stateObject struct {
 	code Code // contract bytecode, which gets set when code is loaded
 
 	originStorage Storage // Storage cache of original entries to dedup rewrites
-	cachedStorage Storage // Storage entry cache to avoid duplicate reads
 	dirtyStorage  Storage // Storage entries that need to be flushed to disk
 
 	// Cache flags.
@@ -117,7 +116,6 @@ func newObject(db *StateDB, address common.Address, data Account) *stateObject {
 		addrHash:      crypto.Keccak256Hash(address[:]),
 		data:          data,
 		originStorage: make(Storage),
-		cachedStorage: make(Storage),
 		dirtyStorage:  make(Storage),
 	}
 }
@@ -161,17 +159,22 @@ func (c *stateObject) getTrie(db Database) Trie {
 	return c.trie
 }
 
-// GetState returns a value in account storage.
+// GetState returns a value from account storage, and also whether the slot is
-func (self *stateObject) GetState(db Database, key common.Hash) common.Hash {
+// dirty in the current transaction execution context.
-	value, exists := self.cachedStorage[key]
+func (self *stateObject) GetState(db Database, key common.Hash) (common.Hash, bool) {
-	if exists {
+	value, dirty := self.dirtyStorage[key]
-		return value
+	if dirty {
+		return value, true
+	}
+	value, cached := self.originStorage[key]
+	if cached {
+		return value, false
 	}
 	// Load from DB in case it is missing.
 	enc, err := self.getTrie(db).TryGet(key[:])
 	if err != nil {
 		self.setError(err)
-		return common.Hash{}
+		return common.Hash{}, false
 	}
 	if len(enc) > 0 {
 		_, content, _, err := rlp.Split(enc)
@@ -181,23 +184,33 @@ func (self *stateObject) GetState(db Database, key common.Hash) common.Hash {
 		value.SetBytes(content)
 	}
 	self.originStorage[key] = value
-	self.cachedStorage[key] = value
+	return value, false
-	return value
 }
 
 // SetState updates a value in account storage.
 func (self *stateObject) SetState(db Database, key, value common.Hash) {
+	// If the new value is the same as old, don't set and don't mark dirty
+	prev, dirty := self.GetState(db, key)
+	if prev == value {
+		return
+	}
+	// New value is different, update and journal the change
+	self.setState(key, value, true)
+
 	self.db.journal.append(storageChange{
-		account:  &self.address,
+		account:   &self.address,
-		key:      key,
+		key:       key,
-		prevalue: self.GetState(db, key),
+		prevValue: prev,
+		prevDirty: dirty,
 	})
-	self.setState(key, value)
 }
 
-func (self *stateObject) setState(key, value common.Hash) {
+func (self *stateObject) setState(key, value common.Hash, dirty bool) {
-	self.cachedStorage[key] = value
+	if dirty {
-	self.dirtyStorage[key] = value
+		self.dirtyStorage[key] = value
+	} else {
+		delete(self.dirtyStorage, key)
+	}
 }
 
 // updateTrie writes cached storage modifications into the object's storage trie.
@@ -289,7 +302,6 @@ func (self *stateObject) deepCopy(db *StateDB) *stateObject {
 	}
 	stateObject.code = self.code
 	stateObject.dirtyStorage = self.dirtyStorage.Copy()
-	stateObject.cachedStorage = self.dirtyStorage.Copy()
 	stateObject.originStorage = self.originStorage.Copy()
 	stateObject.suicided = self.suicided
 	stateObject.dirtyCode = self.dirtyCode

core/state/state_test.go

@@ -96,12 +96,17 @@ func (s *StateSuite) TestNull(c *checker.C) {
 	s.state.CreateAccount(address)
 	//value := common.FromHex("0x823140710bf13990e4500136726d8b55")
 	var value common.Hash
+
 	s.state.SetState(address, common.Hash{}, value)
 	s.state.Commit(false)
-	value = s.state.GetState(address, common.Hash{})
+
+	value, dirty := s.state.GetState(address, common.Hash{})
 	if value != (common.Hash{}) {
 		c.Errorf("expected empty hash. got %x", value)
 	}
+	if dirty {
+		c.Errorf("expected non-dirty, got dirty")
+	}
 }
 
 func (s *StateSuite) TestSnapshot(c *checker.C) {
@@ -110,20 +115,27 @@ func (s *StateSuite) TestSnapshot(c *checker.C) {
 	data1 := common.BytesToHash([]byte{42})
 	data2 := common.BytesToHash([]byte{43})
 
-	// set initial state object value
+	// snapshot the genesis state
+	genesis := s.state.Snapshot()
+
+	// set initial state object value and snapshot it
 	s.state.SetState(stateobjaddr, storageaddr, data1)
-	// get snapshot of current state
 	snapshot := s.state.Snapshot()
 
-	// set new state object value
+	// set a new state object value, revert it and ensure correct content
 	s.state.SetState(stateobjaddr, storageaddr, data2)
-	// restore snapshot
 	s.state.RevertToSnapshot(snapshot)
 
-	// get state storage value
+	value, dirty := s.state.GetState(stateobjaddr, storageaddr)
-	res := s.state.GetState(stateobjaddr, storageaddr)
+	c.Assert(data1, checker.DeepEquals, value)
+	c.Assert(true, checker.DeepEquals, dirty)
 
-	c.Assert(data1, checker.DeepEquals, res)
+	// revert up to the genesis state and ensure correct content
+	s.state.RevertToSnapshot(genesis)
+
+	value, dirty = s.state.GetState(stateobjaddr, storageaddr)
+	c.Assert(common.Hash{}, checker.DeepEquals, value)
+	c.Assert(false, checker.DeepEquals, dirty)
 }
 
 func (s *StateSuite) TestSnapshotEmpty(c *checker.C) {
@@ -208,17 +220,30 @@ func compareStateObjects(so0, so1 *stateObject, t *testing.T) {
 		t.Fatalf("Code mismatch: have %v, want %v", so0.code, so1.code)
 	}
 
-	if len(so1.cachedStorage) != len(so0.cachedStorage) {
+	if len(so1.dirtyStorage) != len(so0.dirtyStorage) {
-		t.Errorf("Storage size mismatch: have %d, want %d", len(so1.cachedStorage), len(so0.cachedStorage))
+		t.Errorf("Dirty storage size mismatch: have %d, want %d", len(so1.dirtyStorage), len(so0.dirtyStorage))
 	}
-	for k, v := range so1.cachedStorage {
+	for k, v := range so1.dirtyStorage {
-		if so0.cachedStorage[k] != v {
+		if so0.dirtyStorage[k] != v {
-			t.Errorf("Storage key %x mismatch: have %v, want %v", k, so0.cachedStorage[k], v)
+			t.Errorf("Dirty storage key %x mismatch: have %v, want %v", k, so0.dirtyStorage[k], v)
 		}
 	}
-	for k, v := range so0.cachedStorage {
+	for k, v := range so0.dirtyStorage {
-		if so1.cachedStorage[k] != v {
+		if so1.dirtyStorage[k] != v {
-			t.Errorf("Storage key %x mismatch: have %v, want none.", k, v)
+			t.Errorf("Dirty storage key %x mismatch: have %v, want none.", k, v)
+		}
+	}
+	if len(so1.originStorage) != len(so0.originStorage) {
+		t.Errorf("Origin storage size mismatch: have %d, want %d", len(so1.originStorage), len(so0.originStorage))
+	}
+	for k, v := range so1.originStorage {
+		if so0.originStorage[k] != v {
+			t.Errorf("Origin storage key %x mismatch: have %v, want %v", k, so0.originStorage[k], v)
+		}
+	}
+	for k, v := range so0.originStorage {
+		if so1.originStorage[k] != v {
+			t.Errorf("Origin storage key %x mismatch: have %v, want none.", k, v)
 		}
 	}
 

core/state/statedb.go

@@ -27,6 +27,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
 )
@@ -236,12 +237,12 @@ func (self *StateDB) GetCodeHash(addr common.Address) common.Hash {
 	return common.BytesToHash(stateObject.CodeHash())
 }
 
-func (self *StateDB) GetState(addr common.Address, bhash common.Hash) common.Hash {
+func (self *StateDB) GetState(addr common.Address, bhash common.Hash) (common.Hash, bool) {
 	stateObject := self.getStateObject(addr)
 	if stateObject != nil {
 		return stateObject.GetState(self.db, bhash)
 	}
-	return common.Hash{}
+	return common.Hash{}, false
 }
 
 // Database retrieves the low level database supporting the lower level trie ops.
@@ -430,24 +431,19 @@ func (self *StateDB) CreateAccount(addr common.Address) {
 	}
 }
 
-func (db *StateDB) ForEachStorage(addr common.Address, cb func(key, value common.Hash) bool) {
+func (db *StateDB) ForEachStorage(addr common.Address, cb func(key, value common.Hash, dirty bool) bool) {
 	so := db.getStateObject(addr)
 	if so == nil {
 		return
 	}
-
-	// When iterating over the storage check the cache first
-	for h, value := range so.cachedStorage {
-		cb(h, value)
-	}
-
 	it := trie.NewIterator(so.getTrie(db.db).NodeIterator(nil))
 	for it.Next() {
-		// ignore cached values
 		key := common.BytesToHash(db.trie.GetKey(it.Key))
-		if _, ok := so.cachedStorage[key]; !ok {
+		if value, dirty := so.dirtyStorage[key]; dirty {
-			cb(key, common.BytesToHash(it.Value))
+			cb(key, value, true)
+			continue
 		}
+		cb(key, common.BytesToHash(it.Value), false)
 	}
 }
 
@@ -524,9 +520,36 @@ func (self *StateDB) RevertToSnapshot(revid int) {
 	self.validRevisions = self.validRevisions[:idx]
 }
 
-// GetRefund returns the current value of the refund counter.
+// GetRefund returns the current value of the refund counter and any out-of-band
-func (self *StateDB) GetRefund() uint64 {
+// refunds at the end of the transaction.
-	return self.refund
+func (self *StateDB) GetRefund(netSstoreMeter bool) uint64 {
+	// If legacy gas metering is used, return the current refund counter
+	refund := self.refund
+	if !netSstoreMeter {
+		return refund
+	}
+	// If we're already using the Constantinople net sstore gas metering, refund noops
+	for addr := range self.journal.dirties {
+		object := self.stateObjects[addr]
+		for key, value := range object.dirtyStorage {
+			// If the slot didn't change in the end, refund most gas
+			if value == object.originStorage[key] {
+				if value == (common.Hash{}) {
+					refund += params.NetSstoreRefundNoopZero
+				} else {
+					refund += params.NetSstoreRefundNoopNonZero
+				}
+				continue
+			}
+			// If the slot did change, but was set to zero, refund
+			if value == (common.Hash{}) {
+				refund += params.NetSstoreRefund
+				continue
+			}
+			// Sorry, no refund for this slot
+		}
+	}
+	return refund
 }
 
 // Finalise finalises the state by removing the self destructed objects

core/state/statedb_test.go

@@ -381,11 +381,19 @@ func (test *snapshotTest) checkEqual(state, checkstate *StateDB) error {
 		checkeq("GetCodeSize", state.GetCodeSize(addr), checkstate.GetCodeSize(addr))
 		// Check storage.
 		if obj := state.getStateObject(addr); obj != nil {
-			state.ForEachStorage(addr, func(key, val common.Hash) bool {
+			state.ForEachStorage(addr, func(key, value common.Hash, dirty bool) bool {
-				return checkeq("GetState("+key.Hex()+")", val, checkstate.GetState(addr, key))
+				v, d := checkstate.GetState(addr, key)
+				if ok := checkeq("GetState("+key.Hex()+").value", value, v); ok {
+					return ok
+				}
+				return checkeq("GetState("+key.Hex()+").dirty", dirty, d)
 			})
-			checkstate.ForEachStorage(addr, func(key, checkval common.Hash) bool {
+			checkstate.ForEachStorage(addr, func(key, value common.Hash, dirty bool) bool {
-				return checkeq("GetState("+key.Hex()+")", state.GetState(addr, key), checkval)
+				v, d := state.GetState(addr, key)
+				if ok := checkeq("GetState("+key.Hex()+").value", v, value); ok {
+					return ok
+				}
+				return checkeq("GetState("+key.Hex()+").dirty", d, dirty)
 			})
 		}
 		if err != nil {
@@ -393,9 +401,11 @@ func (test *snapshotTest) checkEqual(state, checkstate *StateDB) error {
 		}
 	}
 
-	if state.GetRefund() != checkstate.GetRefund() {
+	for _, netGasMetering := range []bool{false, true} {
-		return fmt.Errorf("got GetRefund() == %d, want GetRefund() == %d",
+		if state.GetRefund(netGasMetering) != checkstate.GetRefund(netGasMetering) {
-			state.GetRefund(), checkstate.GetRefund())
+			return fmt.Errorf("got GetRefund(%v) == %d, want GetRefund(%v) == %d",
+				netGasMetering, state.GetRefund(netGasMetering), netGasMetering, checkstate.GetRefund(netGasMetering))
+		}
 	}
 	if !reflect.DeepEqual(state.GetLogs(common.Hash{}), checkstate.GetLogs(common.Hash{})) {
 		return fmt.Errorf("got GetLogs(common.Hash{}) == %v, want GetLogs(common.Hash{}) == %v",

core/state_transition.go

@@ -229,9 +229,11 @@ func (st *StateTransition) TransitionDb() (ret []byte, usedGas uint64, failed bo
 
 func (st *StateTransition) refundGas() {
 	// Apply refund counter, capped to half of the used gas.
-	refund := st.gasUsed() / 2
+	netSstoreMeter := st.evm.ChainConfig().IsConstantinople(st.evm.BlockNumber)
-	if refund > st.state.GetRefund() {
+
-		refund = st.state.GetRefund()
+	refund := st.state.GetRefund(netSstoreMeter)
+	if refund > st.gasUsed()/2 {
+		refund = st.gasUsed() / 2
 	}
 	st.gas += refund
 

core/vm/gas_table.go

@@ -117,23 +117,51 @@ func gasReturnDataCopy(gt params.GasTable, evm *EVM, contract *Contract, stack *
 
 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)
+		y, x         = stack.Back(1), stack.Back(0)
-		val  = evm.StateDB.GetState(contract.Address(), common.BigToHash(x))
+		value, dirty = evm.StateDB.GetState(contract.Address(), common.BigToHash(x))
 	)
-	// This checks for 3 scenario's and calculates gas accordingly
+	// The legacy gas metering only takes into consideration the current state
-	// 1. From a zero-value address to a non-zero value         (NEW VALUE)
+	if !evm.chainRules.IsConstantinople {
-	// 2. From a non-zero value address to a zero-value address (DELETE)
+		// This checks for 3 scenario's and calculates gas accordingly
-	// 3. From a non-zero to a non-zero                         (CHANGE)
+		// 1. From a zero-value address to a non-zero value         (NEW VALUE)
-	if val == (common.Hash{}) && y.Sign() != 0 {
+		// 2. From a non-zero value address to a zero-value address (DELETE)
-		// 0 => non 0
+		// 3. From a non-zero to a non-zero                         (CHANGE)
-		return params.SstoreSetGas, nil
+		switch {
-	} else if val != (common.Hash{}) && y.Sign() == 0 {
+		case value == (common.Hash{}) && y.Sign() != 0: // 0 => non 0
-		// non 0 => 0
+			return params.SstoreSetGas, nil
-		evm.StateDB.AddRefund(params.SstoreRefundGas)
+		case value != (common.Hash{}) && y.Sign() == 0: // non 0 => 0
-		return params.SstoreClearGas, nil
+			evm.StateDB.AddRefund(params.SstoreRefundGas)
-	} else {
+			return params.SstoreClearGas, nil
-		// non 0 => non 0 (or 0 => 0)
+		default: // non 0 => non 0 (or 0 => 0)
-		return params.SstoreResetGas, nil
+			return params.SstoreResetGas, nil
+		}
+	}
+	// The new gas metering is based on net gas costs (EIP-1087)
+	//
+	// 0. A ‘dirty map’ for each transaction is maintained, tracking all storage
+	//    slots in all contracts that have been modified in the current transaction.
+	//    The dirty map is scoped in the same manner as updates to storage, meaning
+	//    that changes to the dirty map in a call that later reverts are not retained.
+	// 1. When a storage slot is written to with the value it already contains, 200
+	//    gas is deducted, but is not explicitly marked dirty.
+	// 2. When a storage slot’s value is changed for the first time, the slot is
+	//    marked as dirty. If the slot was previously set to 0, 20000 gas is deducted;
+	//    otherwise, 5000 gas is deducted.
+	// 2. When a storage slot that is already in the dirty map is written to, 200
+	//    gas is deducted.
+	// 3. At the end of the transaction, for each slot in the dirty map:
+	//      * If the slot was 0 before the transaction and is 0 now, refund 19800 gas.
+	//      * If the slot was nonzero before the transaction and its value has not changed, refund 4800 gas.
+	//      * If the slot was nonzero before the transaction and is 0 now, refund 10000 gas.
+	switch {
+	case value == common.BigToHash(y): // noop
+		return params.NetSstoreNoopGas, nil
+	case !dirty && y.Sign() != 0 && value == (common.Hash{}): // clean(0) => anything
+		return params.NetSstoreCleanInitgas, nil
+	case !dirty && y.Sign() != 0: // clean(non 0) => anything
+		return params.NetSstoreCleanUpdateGas, nil
+	default: // dirty(anything) => anything
+		return params.NetSstoreDirtyGas, nil
 	}
 }
 

core/vm/instructions.go

@@ -604,7 +604,7 @@ func opMstore8(pc *uint64, interpreter *EVMInterpreter, contract *Contract, memo
 
 func opSload(pc *uint64, interpreter *EVMInterpreter, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
 	loc := stack.peek()
-	val := interpreter.evm.StateDB.GetState(contract.Address(), common.BigToHash(loc))
+	val, _ := interpreter.evm.StateDB.GetState(contract.Address(), common.BigToHash(loc))
 	loc.SetBytes(val.Bytes())
 	return nil, nil
 }

core/vm/interface.go

@@ -40,9 +40,9 @@ type StateDB interface {
 	GetCodeSize(common.Address) int
 
 	AddRefund(uint64)
-	GetRefund() uint64
+	GetRefund(bool) uint64
 
-	GetState(common.Address, common.Hash) common.Hash
+	GetState(common.Address, common.Hash) (common.Hash, bool)
 	SetState(common.Address, common.Hash, common.Hash)
 
 	Suicide(common.Address) bool
@@ -61,7 +61,7 @@ type StateDB interface {
 	AddLog(*types.Log)
 	AddPreimage(common.Hash, []byte)
 
-	ForEachStorage(common.Address, func(common.Hash, common.Hash) bool)
+	ForEachStorage(common.Address, func(common.Hash, common.Hash, bool) bool)
 }
 
 // CallContext provides a basic interface for the EVM calling conventions. The EVM EVM

core/vm/interpreter.go

@@ -133,7 +133,6 @@ func (in *EVMInterpreter) Run(contract *Contract, input []byte) (ret []byte, err
 			in.intPool = nil
 		}()
 	}
-
 	// Increment the call depth which is restricted to 1024
 	in.evm.depth++
 	defer func() { in.evm.depth-- }()

eth/tracers/tracer.go

@@ -214,7 +214,7 @@ func (dw *dbWrapper) pushObject(vm *duktape.Context) {
 		hash := popSlice(ctx)
 		addr := popSlice(ctx)
 
-		state := dw.db.GetState(common.BytesToAddress(addr), common.BytesToHash(hash))
+		state, _ := dw.db.GetState(common.BytesToAddress(addr), common.BytesToHash(hash))
 
 		ptr := ctx.PushFixedBuffer(len(state))
 		copy(makeSlice(ptr, uint(len(state))), state[:])

internal/ethapi/api.go

@@ -597,7 +597,7 @@ func (s *PublicBlockChainAPI) GetStorageAt(ctx context.Context, address common.A
 	if state == nil || err != nil {
 		return nil, err
 	}
-	res := state.GetState(address, common.HexToHash(key))
+	res, _ := state.GetState(address, common.HexToHash(key))
 	return res[:], state.Error()
 }
 

params/config.go

@@ -334,7 +334,7 @@ func (err *ConfigCompatError) Error() string {
 type Rules struct {
 	ChainID                                   *big.Int
 	IsHomestead, IsEIP150, IsEIP155, IsEIP158 bool
-	IsByzantium                               bool
+	IsByzantium, IsConstantinople             bool
 }
 
 // Rules ensures c's ChainID is not nil.
@@ -343,5 +343,12 @@ func (c *ChainConfig) Rules(num *big.Int) Rules {
 	if chainID == nil {
 		chainID = new(big.Int)
 	}
-	return Rules{ChainID: new(big.Int).Set(chainID), IsHomestead: c.IsHomestead(num), IsEIP150: c.IsEIP150(num), IsEIP155: c.IsEIP155(num), IsEIP158: c.IsEIP158(num), IsByzantium: c.IsByzantium(num)}
+	return Rules{
+		ChainID:          new(big.Int).Set(chainID),
+		IsHomestead:      c.IsHomestead(num),
+		IsEIP150:         c.IsEIP150(num),
+		IsEIP155:         c.IsEIP155(num),
+		IsEIP158:         c.IsEIP158(num),
+		IsByzantium:      c.IsByzantium(num),
+		IsConstantinople: c.IsConstantinople(num)}
 }

params/protocol_params.go

@@ -36,15 +36,25 @@ const (
 	TxGasContractCreation uint64 = 53000 // Per transaction that creates a contract. NOTE: Not payable on data of calls between transactions.
 	TxDataZeroGas         uint64 = 4     // Per byte of data attached to a transaction that equals zero. NOTE: Not payable on data of calls between transactions.
 	QuadCoeffDiv          uint64 = 512   // Divisor for the quadratic particle of the memory cost equation.
-	SstoreSetGas          uint64 = 20000 // Once per SLOAD operation.
 	LogDataGas            uint64 = 8     // Per byte in a LOG* operation's data.
 	CallStipend           uint64 = 2300  // Free gas given at beginning of call.
 
-	Sha3Gas          uint64 = 30    // Once per SHA3 operation.
+	Sha3Gas     uint64 = 30 // Once per SHA3 operation.
-	Sha3WordGas      uint64 = 6     // Once per word of the SHA3 operation's data.
+	Sha3WordGas uint64 = 6  // Once per word of the SHA3 operation's data.
-	SstoreResetGas   uint64 = 5000  // Once per SSTORE operation if the zeroness changes from zero.
+
-	SstoreClearGas   uint64 = 5000  // Once per SSTORE operation if the zeroness doesn't change.
+	SstoreSetGas    uint64 = 20000 // Once per SSTORE operation.
-	SstoreRefundGas  uint64 = 15000 // Once per SSTORE operation if the zeroness changes to zero.
+	SstoreResetGas  uint64 = 5000  // Once per SSTORE operation if the zeroness changes from zero.
+	SstoreClearGas  uint64 = 5000  // Once per SSTORE operation if the zeroness doesn't change.
+	SstoreRefundGas uint64 = 15000 // Once per SSTORE operation if the zeroness changes to zero.
+
+	NetSstoreNoopGas           uint64 = 200   // Once per SSTORE operation if the value doesn't change.
+	NetSstoreDirtyGas          uint64 = 200   // Once per SSTORE operation from dirty.
+	NetSstoreCleanInitgas      uint64 = 20000 // Once per SSTORE operation from clean zero.
+	NetSstoreCleanUpdateGas    uint64 = 5000  // Once per SSTORE operation from clean non-zero.
+	NetSstoreRefundNoopZero    uint64 = 19800 // Once per dirty slot if it was changed from zero to non-zero and back to zero.
+	NetSstoreRefundNoopNonZero uint64 = 4800  // Once per dirty slot if it was changed from non-zero to anything and back to the orignal.
+	NetSstoreRefund            uint64 = 10000 // Once per dirty slot if it was changed from non-zero to zero.
+
 	JumpdestGas      uint64 = 1     // Refunded gas, once per SSTORE operation if the zeroness changes to zero.
 	EpochDuration    uint64 = 30000 // Duration between proof-of-work epochs.
 	CallGas          uint64 = 40    // Once per CALL operation & message call transaction.

tests/vm_test_util.go

@@ -100,7 +100,7 @@ func (t *VMTest) Run(vmconfig vm.Config) error {
 	}
 	for addr, account := range t.json.Post {
 		for k, wantV := range account.Storage {
-			if haveV := statedb.GetState(addr, k); haveV != wantV {
+			if haveV, _ := statedb.GetState(addr, k); haveV != wantV {
 				return fmt.Errorf("wrong storage value at %x:\n  got  %x\n  want %x", k, haveV, wantV)
 			}
 		}