Implement effects of emptiness change.

libethashseal/Ethash.cpp

@@ -86,7 +86,7 @@ EVMSchedule const& Ethash::evmSchedule(EnvInfo const& _envInfo) const
 {
 	if (_envInfo.number() >= chainParams().u256Param("EIP158ForkBlock"))
 		return EIP158Schedule;
-	if (_envInfo.number() >= chainParams().u256Param("EIP150ForkBlock"))
+	else if (_envInfo.number() >= chainParams().u256Param("EIP150ForkBlock"))
 		return EIP150Schedule;
 	else if (_envInfo.number() >= chainParams().u256Param("homsteadForkBlock"))
 		return HomesteadSchedule;

libethereum/Account.h

@@ -111,6 +111,9 @@ class Account
 	/// @returns true if the account is unchanged from creation.
 	bool isDirty() const { return !m_isUnchanged; }
 
+	/// @returns true if the nonce, balance and code is zero / empty. Code is considered empty
+	/// during creation phase.
+	bool isEmpty() const { return nonce() == 0 && balance() == 0 && ((isFreshCode() && code().empty()) || codeHash() == EmptySHA3); }
 
 	/// @returns the balance of this account. Can be altered in place.
 	u256& balance() { return m_balance; }

libethereum/Block.cpp

@@ -625,8 +625,9 @@ u256 Block::enact(VerifiedBlockRef const& _block, BlockChain const& _bc)
 		applyRewards(rewarded, _bc.chainParams().blockReward);
 
 	// Commit all cached state changes to the state trie.
+	bool killEmptyAccounts = m_currentBlock.number() >= _bc.chainParams().u256Param("EIP158ForkBlock");
 	DEV_TIMED_ABOVE("commit", 500)
-		m_state.commit();
+		m_state.commit(killEmptyAccounts);
 
 	// Hash the state trie and check against the state_root hash in m_currentBlock.
 	if (m_currentBlock.stateRoot() != m_previousBlock.stateRoot() && m_currentBlock.stateRoot() != rootHash())
@@ -688,7 +689,7 @@ void Block::performIrregularModifications()
 		Addresses allDAOs = childDaos();
 		for (Address const& dao: allDAOs)
 			m_state.transferBalance(dao, recipient, m_state.balance(dao));
-		m_state.commit();
+		m_state.commit(false);
 	}
 }
 
@@ -768,7 +769,9 @@ void Block::commitToSeal(BlockChain const& _bc, bytes const& _extraData)
 	applyRewards(uncleBlockHeaders, _bc.chainParams().blockReward);
 
 	// Commit any and all changes to the trie that are in the cache, then update the state root accordingly.
-	m_state.commit();
+	bool killEmptyAccounts = m_currentBlock.number() >= _bc.chainParams().u256Param("EIP158ForkBlock");
+	DEV_TIMED_ABOVE("commit", 500)
+		m_state.commit(killEmptyAccounts);
 
 	clog(StateDetail) << "Post-reward stateRoot:" << m_state.rootHash();
 	clog(StateDetail) << m_state;

libethereum/ExtVM.h

@@ -79,7 +79,7 @@ class ExtVM: public ExtVMFace
 	virtual bool exists(Address _a) override final
 	{
 		if (evmSchedule().emptinessIsNonexistence())
-			return m_s.accountNonemptyOrExisting(_a);
+			return m_s.accountNonemptyAndExisting(_a);
 		else
 			return m_s.addressInUse(_a);
 	}

libethereum/State.cpp

@@ -66,6 +66,7 @@ State::State(State const& _s):
 	m_db(_s.m_db),
 	m_state(&m_db, _s.m_state.root(), Verification::Skip),
 	m_cache(_s.m_cache),
+	m_unchangedCacheEntries(_s.m_unchangedCacheEntries),
 	m_touched(_s.m_touched),
 	m_accountStartNonce(_s.m_accountStartNonce)
 {
@@ -116,7 +117,7 @@ OverlayDB State::openDB(std::string const& _basePath, h256 const& _genesisHash,
 void State::populateFrom(AccountMap const& _map)
 {
 	eth::commit(_map, m_state);
-	commit();
+	commit(false);
 }
 
 u256 const& State::requireAccountStartNonce() const
@@ -134,6 +135,13 @@ void State::noteAccountStartNonce(u256 const& _actual)
 		BOOST_THROW_EXCEPTION(IncorrectAccountStartNonceInState());
 }
 
+void State::killEmptyAccounts()
+{
+	for (auto& i: m_cache)
+		if (i.second.isDirty() && i.second.isEmpty())
+			i.second.kill();
+}
+
 void State::paranoia(std::string const& _when, bool _enforceRefs) const
 {
 #if ETH_PARANOIA && !ETH_FATDB
@@ -158,6 +166,7 @@ State& State::operator=(State const& _s)
 	m_db = _s.m_db;
 	m_state.open(&m_db, _s.m_state.root(), Verification::Skip);
 	m_cache = _s.m_cache;
+	m_unchangedCacheEntries = _s.m_unchangedCacheEntries;
 	m_touched = _s.m_touched;
 	m_accountStartNonce = _s.m_accountStartNonce;
 	paranoia("after state cloning (assignment op)", true);
@@ -266,8 +275,10 @@ void State::clearCacheIfTooLarge() const
 	}
 }
 
-void State::commit()
+void State::commit(bool _killEmptyAccounts)
 {
+	if (_killEmptyAccounts)
+		killEmptyAccounts();
 	m_touched += dev::eth::commit(m_cache, m_state);
 	m_cache.clear();
 }
@@ -301,6 +312,14 @@ bool State::addressInUse(Address const& _id) const
 	return !!account(_id);
 }
 
+bool State::accountNonemptyAndExisting(Address const& _address) const
+{
+	if (Account const* a = account(_address))
+		return !a->isEmpty();
+	else
+		return false;
+}
+
 bool State::addressHasCode(Address const& _id) const
 {
 	if (auto a = account(_id))
@@ -542,7 +561,8 @@ std::pair<ExecutionResult, TransactionReceipt> State::execute(EnvInfo const& _en
 		m_cache.clear();
 	else
 	{
-		commit();
+		bool killEmptyAccounts = _envInfo.number() >= _sealEngine->chainParams().u256Param("EIP158ForkBlock");
+		commit(killEmptyAccounts);
 
 #if ETH_PARANOIA && !ETH_FATDB
 		ctrace << "Executed; now" << rootHash();

libethereum/State.h

@@ -159,9 +159,9 @@ class State
 	/// Check if the address is in use.
 	bool addressInUse(Address const& _address) const;
 
-	/// Check if the account does not exist in the state or is empty (nonce == 0, balance == 0, code empty).
+	/// Check if the account exists in the state and is non empty (nonce > 0 || balance > 0 || code nonempty).
 	/// These two notions are equivalent after EIP158.
-	bool accountNonemptyOrExisting(Address const& _address) const;
+	bool accountNonemptyAndExisting(Address const& _address) const;
 
 	/// Check if the address contains executable code.
 	bool addressHasCode(Address const& _address) const;
@@ -243,7 +243,8 @@ class State
 	StateDiff diff(State const& _c, bool _quick = false) const;
 
 	/// Commit all changes waiting in the address cache to the DB.
-	void commit();
+	/// @param _killEmptyAccounts if true, will remove all "touched" empty accounts from the state.
+	void commit(bool _killEmptyAccounts);
 
 	/// Resets any uncommitted changes to the cache.
 	void setRoot(h256 const& _root);
@@ -254,6 +255,9 @@ class State
 	void noteAccountStartNonce(u256 const& _actual);
 
 private:
+	/// Turns all "touched" empty accounts into non-alive accounts.
+	void killEmptyAccounts();
+
 	/// @returns the account at the given address or a null pointer if it does not exist.
 	/// The pointer is valid until the next access to the state or account.
 	Account const* account(Address const& _a, bool _requireCode = false) const;

libevm/VM.cpp

@@ -209,10 +209,12 @@ void VM::interpretCases()
 			m_runGas = toUint64(m_schedule->suicideGas);
 			Address dest = asAddress(*m_sp);
 
-			// After EIP150 hard fork charge additional cost of sending
-			// ethers to non-existing account.
-			if (m_schedule->suicideChargesNewAccountGas() && !m_ext->exists(dest))
-				m_runGas += m_schedule->callNewAccountGas;
+			// After EIP158 zero-value suicides do not have to pay account creation gas.
+			if (m_ext->balance(m_ext->myAddress) > 0 || m_schedule->zeroValueTransferChargesNewAccountGas())
+				// After EIP150 hard fork charge additional cost of sending
+				// ethers to non-existing account.
+				if (m_schedule->suicideChargesNewAccountGas() && !m_ext->exists(dest))
+					m_runGas += m_schedule->callNewAccountGas;
 
 			onOperation();
 			updateIOGas();

libevm/VMCalls.cpp

@@ -138,7 +138,8 @@ bool VM::caseCallSetup(CallParameters *callParams)
 	m_runGas = toUint64(m_schedule->callGas);
 
 	if (m_op == Instruction::CALL && !m_ext->exists(asAddress(*(m_sp - 1))))
-		m_runGas += toUint64(m_schedule->callNewAccountGas);
+		if (*(m_sp - 2) > 0 || m_schedule->zeroValueTransferChargesNewAccountGas())
+			m_runGas += toUint64(m_schedule->callNewAccountGas);
 
 	if (m_op != Instruction::DELEGATECALL && *(m_sp - 2) > 0)
 		m_runGas += toUint64(m_schedule->callValueTransferGas);

libevmcore/EVMSchedule.h

@@ -74,6 +74,7 @@ struct EVMSchedule
 	bool staticCallDepthLimit() const { return !eip150Mode; }
 	bool suicideChargesNewAccountGas() const { return eip150Mode; }
 	bool emptinessIsNonexistence() const { return eip158Mode; }
+	bool zeroValueTransferChargesNewAccountGas() const { return !eip158Mode; }
 };
 
 static const EVMSchedule DefaultSchedule = EVMSchedule();

test/BlockChainHelper.cpp

@@ -55,7 +55,7 @@ TestBlock::TestBlock(mObject const& _blockObj, mObject const& _stateObj):
 
 	m_state = std::unique_ptr<State>(new State(0, OverlayDB(State::openDB(m_tempDirState.get()->path(), h256{}, WithExisting::Kill)), BaseState::Empty));
 	ImportTest::importState(_stateObj, *m_state.get());
-	m_state.get()->commit();
+	m_state.get()->commit(false);
 
 	json_spirit::mObject state = _stateObj;
 	dev::test::replaceLLLinState(state);

test/TestHelper.cpp

@@ -166,9 +166,10 @@ bytes ImportTest::executeTest(eth::Network _sealEngineNetwork)
 {
 	ExecutionResult res;
 	eth::State tmpState = m_statePre;
+	unique_ptr<SealEngineFace> se;
 	try
 	{
-		unique_ptr<SealEngineFace> se(ChainParams(genesisInfo(_sealEngineNetwork)).createSealEngine());
+		se.reset(ChainParams(genesisInfo(_sealEngineNetwork)).createSealEngine());
 		std::pair<ExecutionResult, TransactionReceipt>  execOut = m_statePre.execute(m_envInfo, se.get(), m_transaction);
 		res = execOut.first;
 		m_logs = execOut.second.log();
@@ -182,7 +183,8 @@ bytes ImportTest::executeTest(eth::Network _sealEngineNetwork)
 		cnote << "state execution exception: " << _e.what();
 	}
 
-	m_statePre.commit();
+	bool killEmptyAccounts = m_envInfo.number() >= se->chainParams().u256Param("EIP158ForkBlock");
+	m_statePre.commit(killEmptyAccounts);
 	m_statePost = m_statePre;
 	m_statePre = tmpState;
 

test/TestUtils.cpp

@@ -102,7 +102,7 @@ void ClientBaseFixture::enumerateClients(std::function<void(Json::Value const&,
 	enumerateBlockchains([&callback](Json::Value const& _json, BlockChain const& _bc, State _state) -> void
 	{
 		cerr << "void ClientBaseFixture::enumerateClients. FixedClient now accepts block not sate!" << endl;
-		_state.commit(); //unused variable. remove this line
+		_state.commit(false); //unused variable. remove this line
 		eth::Block b(Block::Null);
 		b.noteChain(_bc);
 		FixedClient client(_bc, b);