core/state: remove reset-account notion in statedb

core/state/statedb.go

@@ -618,16 +618,16 @@ func (s *StateDB) setStateObject(object *stateObject) {
 func (s *StateDB) GetOrNewStateObject(addr common.Address) *stateObject {
 	stateObject := s.getStateObject(addr)
 	if stateObject == nil {
-		stateObject, _ = s.createObject(addr)
+		stateObject = s.createObject(addr)
 	}
 	return stateObject
 }
 
 // createObject creates a new state object. If there is an existing account with
 // the given address, it is overwritten and returned as the second return value.
-func (s *StateDB) createObject(addr common.Address) (newobj, prev *stateObject) {
+func (s *StateDB) createObject(addr common.Address) *stateObject {
-	prev = s.getDeletedStateObject(addr) // Note, prev might have been deleted, we need that!
+	prev := s.getDeletedStateObject(addr) // Note, prev might have been deleted, we need that!
-	newobj = newObject(s, addr, nil)
+	newobj := newObject(s, addr, nil)
 	if prev == nil {
 		s.journal.append(createObjectChange{account: &addr})
 	} else {
@@ -662,27 +662,13 @@ func (s *StateDB) createObject(addr common.Address) (newobj, prev *stateObject)
 	newobj.created = true
 
 	s.setStateObject(newobj)
-	if prev != nil && !prev.deleted {
+	return newobj
-		return newobj, prev
-	}
-	return newobj, nil
 }
 
-// CreateAccount explicitly creates a state object. If a state object with the address
+// CreateAccount creates a new account at the given address. This function
-// already exists the balance is carried over to the new account.
+// assumes the address is unoccupied to avoid unintentional overwrites.
-//
-// CreateAccount is called during the EVM CREATE operation. The situation might arise that
-// a contract does the following:
-//
-//  1. sends funds to sha(account ++ (nonce + 1))
-//  2. tx_create(sha(account ++ nonce)) (note that this gets the address of 1)
-//
-// Carrying over the balance ensures that Ether doesn't disappear.
 func (s *StateDB) CreateAccount(addr common.Address) {
-	newObj, prev := s.createObject(addr)
+	s.createObject(addr)
-	if prev != nil {
-		newObj.setBalance(prev.data.Balance)
-	}
 }
 
 // Copy creates a deep, independent copy of the state.

core/state/statedb_test.go

@@ -1104,40 +1104,6 @@ func TestStateDBTransientStorage(t *testing.T) {
 	}
 }
 
-func TestResetObject(t *testing.T) {
-	var (
-		disk     = rawdb.NewMemoryDatabase()
-		tdb      = trie.NewDatabase(disk, nil)
-		db       = NewDatabaseWithNodeDB(disk, tdb)
-		snaps, _ = snapshot.New(snapshot.Config{CacheSize: 10}, disk, tdb, types.EmptyRootHash)
-		state, _ = New(types.EmptyRootHash, db, snaps)
-		addr     = common.HexToAddress("0x1")
-		slotA    = common.HexToHash("0x1")
-		slotB    = common.HexToHash("0x2")
-	)
-	// Initialize account with balance and storage in first transaction.
-	state.SetBalance(addr, big.NewInt(1))
-	state.SetState(addr, slotA, common.BytesToHash([]byte{0x1}))
-	state.IntermediateRoot(true)
-
-	// Reset account and mutate balance and storages
-	state.CreateAccount(addr)
-	state.SetBalance(addr, big.NewInt(2))
-	state.SetState(addr, slotB, common.BytesToHash([]byte{0x2}))
-	root, _ := state.Commit(0, true)
-
-	// Ensure the original account is wiped properly
-	snap := snaps.Snapshot(root)
-	slot, _ := snap.Storage(crypto.Keccak256Hash(addr.Bytes()), crypto.Keccak256Hash(slotA.Bytes()))
-	if len(slot) != 0 {
-		t.Fatalf("Unexpected storage slot")
-	}
-	slot, _ = snap.Storage(crypto.Keccak256Hash(addr.Bytes()), crypto.Keccak256Hash(slotB.Bytes()))
-	if !bytes.Equal(slot, []byte{0x2}) {
-		t.Fatalf("Unexpected storage slot value %v", slot)
-	}
-}
-
 func TestDeleteStorage(t *testing.T) {
 	var (
 		disk     = rawdb.NewMemoryDatabase()

core/vm/evm.go

@@ -441,7 +441,9 @@ func (evm *EVM) create(caller ContractRef, codeAndHash *codeAndHash, gas uint64,
 	}
 	// Create a new account on the state
 	snapshot := evm.StateDB.Snapshot()
-	evm.StateDB.CreateAccount(address)
+	if !evm.StateDB.Exist(address) {
+		evm.StateDB.CreateAccount(address)
+	}
 	if evm.chainRules.IsEIP158 {
 		evm.StateDB.SetNonce(address, 1)
 	}

core/vm/interface.go

@@ -26,6 +26,8 @@ import (
 
 // StateDB is an EVM database for full state querying.
 type StateDB interface {
+	// CreateAccount creates a new account at the given address. This function
+	// assumes the address is unoccupied to avoid unintentional overwrites.
 	CreateAccount(common.Address)
 
 	SubBalance(common.Address, *big.Int)