core/state: do not journal preimages

We do not strictly need to journal preimages: preimages are stored and
served for the benefit of remote RPC users, e.g. for debugging solidity
storage. There is no 'consensus requirement' for these keys to be
reverted in case of reverted scopes.

core/state/journal.go

@@ -132,10 +132,6 @@ func (j *journal) JournalLog(txHash common.Hash) {
 	j.append(addLogChange{txhash: txHash})
 }
 
-func (j *journal) JournalAddPreimage(hash common.Hash) {
-	j.append(addPreimageChange{hash: hash})
-}
-
 func (j *journal) JournalRefund(prev uint64) {
 	j.append(refundChange{prev: prev})
 }
@@ -207,7 +203,6 @@ func (j *journal) JournalReset(address common.Address,
 	prevAccountOriginExist bool,
 	prevAccountOrigin []byte,
 	prevStorageOrigin map[common.Hash][]byte) {
-
 	j.append(resetObjectChange{
 		account:                &address,
 		prev:                   prev,
@@ -264,9 +259,6 @@ type (
 	addLogChange struct {
 		txhash common.Hash
 	}
-	addPreimageChange struct {
-		hash common.Hash
-	}
 	touchChange struct {
 		account *common.Address
 	}
@@ -399,14 +391,6 @@ func (ch addLogChange) dirtied() *common.Address {
 	return nil
 }
 
-func (ch addPreimageChange) revert(s *StateDB) {
-	delete(s.preimages, ch.hash)
-}
-
-func (ch addPreimageChange) dirtied() *common.Address {
-	return nil
-}
-
 func (ch accessListAddAccountChange) revert(s *StateDB) {
 	/*
 		One important invariant here, is that whenever a (addr, slot) is added, if the

core/state/statedb.go

@@ -230,7 +230,6 @@ func (s *StateDB) Logs() []*types.Log {
 // AddPreimage records a SHA3 preimage seen by the VM.
 func (s *StateDB) AddPreimage(hash common.Hash, preimage []byte) {
 	if _, ok := s.preimages[hash]; !ok {
-		s.journal.JournalAddPreimage(hash)
 		pi := make([]byte, len(preimage))
 		copy(pi, preimage)
 		s.preimages[hash] = pi