[1] <ARRAY>.LENGTH SHOULD NOT BE LOOKED UP IN EVERY LOOP OF A FOR-LOOP
The overheads outlined below are PER LOOP, excluding the first loop
-storage arrays incur a Gwarmaccess (100 gas) -memory arrays use MLOAD (3 gas) -calldata arrays use CALLDATALOAD (3 gas) Caching the length changes each of these to a DUP (3 gas), and gets rid of the extra DUP needed to store the stack offset.
There is 1 instance of this issue:
File: 2022-10-zksync/ethereum/contracts/zksync/facets/Executor.sol
111: for (uint256 i = 0; i < emittedL2Logs.length; i = i.uncheckedAdd(L2_TO_L1_LOG_SERIALIZE_SIZE)) {
[2] USAGE OF UINTS/INTS SMALLER THAN 32 BYTES (256 BITS) INCURS OVERHEAD
When using elements that are smaller than 32 bytes, your contract’s gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller than that, the EVM must use more operations in order to reduce the size of the element from 32 bytes to the desired size.
https://docs.soliditylang.org/en/v0.8.11/internals/layout_in_storage.html Use a larger size then downcast where needed
There are 33 instances of this issue
File: 2022-10-zksync/ethereum/contracts/zksync/DiamondInit.sol
30: uint64 _genesisIndexRepeatedStorageChanges,
File: 2022-10-zksync/ethereum/contracts/zksync/Storage.sol
40: uint8 l2ShardId;
42: uint16 txNumberInBlock;
54: uint16 txNumberInBlock;
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Storage.sol#L40
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Storage.sol#L42
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Storage.sol#L54
File: 2022-10-zksync/ethereum/contracts/zksync/facets/Executor.sol
367: uint64(0),
File: 2022-10-zksync/ethereum/contracts/zksync/facets/Mailbox.sol
92: uint32
125: uint64 expirationBlock = uint64(block.number + PRIORITY_EXPIRATION);
150: uint64 _expirationBlock,
169: layer2Tip: uint192(0)
File: 2022-10-zksync/ethereum/contracts/zksync/libraries/Diamond.sol
24: uint16 selectorPosition;
33: uint16 facetPosition;
190: ds.facetToSelectors[_facet].facetPosition = uint16(ds.facets.length);
207: uint16 selectorPosition = uint16(ds.facetToSelectors[_facet].selectors.length);
239: ds.selectorToFacet[lastSelector].selectorPosition = uint16(selectorPosition);
268: ds.facetToSelectors[lastFacet].facetPosition = uint16(facetPosition);
File: 2022-10-zksync/ethereum/contracts/zksync/interfaces/IExecutor.sol
16: uint64 blockNumber;
18: uint64 indexRepeatedStorageChanges;
41: uint64 blockNumber;
42: uint64 timestamp;
43: uint64 indexRepeatedStorageChanges;
File: 2022-10-zksync/ethereum/contracts/bridge/L1ERC20Bridge.sol
185: uint16 _l2TxNumberInBlock,
228: uint16 _l2TxNumberInBlock,
273: (uint32 functionSignature, uint256 offset) = UnsafeBytes.readUint32(_l2ToL1message, 0);
File: 2022-10-zksync/ethereum/contracts/bridge/L1EthBridge.sol
138: uint16 _l2TxNumberInBlock,
185: uint16 _l2TxNumberInBlock,
223: (uint32 functionSignature, uint256 offset) = UnsafeBytes.readUint32(_message, 0);
File: 2022-10-zksync/ethereum/contracts/bridge/interfaces/IL1Bridge.sol
29: uint16 _l2TxNumberInBlock,
36: uint16 _l2TxNumberInBlock,
File: 2022-10-zksync/ethereum/contracts/common/L2ContractHelper.sol
26: uint160 constant SYSTEM_CONTRACTS_OFFSET = 0x8000;
64: uint8 version = uint8(_bytecodeHash[0]);
File: 2022-10-zksync/zksync/contracts/bridge/L2StandardERC20.sol
29: uint8 private decimals_;
126: function decimals() public view override returns (uint8) {
File: 2022-10-zksync/zksync/contracts/bridge/interfaces/IL1Bridge.sol
10: uint16 _l2TxNumberInBlock,
[3] ABI.ENCODE() IS LESS EFFICIENT THAN ABI.ENCODEPACKED()
There are 16 instances of this issue:
File: 2022-10-zksync/ethereum/contracts/zksync/facets/DiamondCut.sol
27: s.diamondCutStorage.proposedDiamondCutHash = keccak256(abi.encode(_facetCuts, _initAddress));
61: keccak256(abi.encode(_diamondCut.facetCuts, _diamondCut.initAddress)),
File: 2022-10-zksync/ethereum/contracts/zksync/facets/Executor.sol
85: return keccak256(abi.encode(_previousBlock.blockHash, _newBlock.newStateRoot));
122: chainedPriorityTxsHash = keccak256(abi.encode(chainedPriorityTxsHash, canonicalTxHash));
182: concatHash = keccak256(abi.encode(concatHash, priorityOp.canonicalTxHash));
359: return keccak256(abi.encode(passThroughDataHash, metadataHash, auxiliaryOutputHash));
381: return abi.encode(_block.l2LogsTreeRoot, l2ToL1LogsHash, initialStorageChangesHash, repeatedStorageChangesHash);
386: return keccak256(abi.encode(_storedBlockInfo));
File: 2022-10-zksync/ethereum/contracts/zksync/facets/Mailbox.sol
163: canonicalTxHash = keccak256(abi.encode(transaction));
File: 2022-10-zksync/ethereum/contracts/zksync/libraries/Merkle.sol
30: currentHash = keccak256(abi.encode(currentHash, _path[i]));
32: currentHash = keccak256(abi.encode(_path[i], currentHash));
File: 2022-10-zksync/ethereum/contracts/bridge/L1ERC20Bridge.sol
82: bytes memory create2Input = abi.encode(address(this), l2ProxyTokenBytecodeHash, _governor);
168: data = abi.encode(data1, data2, data3);
283: bytes32 constructorInputHash = keccak256(abi.encode(address(l2TokenFactory), ""));
File: 2022-10-zksync/ethereum/contracts/bridge/L1EthBridge.sol
58: bytes memory create2Input = abi.encode(address(this));
File: 2022-10-zksync/zksync/contracts/bridge/L2ERC20Bridge.sol
114: bytes32 constructorInputHash = keccak256(abi.encode(address(l2TokenFactory), ""));
[4] FUNCTIONS GUARANTEED TO REVERT WHEN CALLED BY NORMAL USERS CAN BE MARKED PAYABLE
If a function modifier such as onlyOwner is used, the function will revert if a normal user tries to pay the function. Marking the function as payable will lower the gas cost for legitimate callers because the compiler will not include checks for whether a payment was provided. The extra opcodes avoided are CALLVALUE(2),DUP1(3),ISZERO(3),PUSH2(3),JUMPI(10),PUSH1(3),DUP1(3),REVERT(0),JUMPDEST(1),POP(2), which costs an average of about 21 gas per call to the function, in addition to the extra deployment cost
There are 21 instances of this issue:
File: 2022-10-zksync/ethereum/contracts/zksync/facets/DiamondCut.sol
35: function cancelDiamondCutProposal() external onlyGovernor {
46: function executeDiamondCutProposal(Diamond.DiamondCutData calldata _diamondCut) external onlyGovernor {
78: function emergencyFreezeDiamond() external onlyGovernor {
91: function unfreezeDiamond() external onlyGovernor {
File: 2022-10-zksync/ethereum/contracts/zksync/facets/Executor.sol
152-156: function commitBlocks(StoredBlockInfo memory _lastCommittedBlockData, CommitBlockInfo[] calldata _newBlocksData)
external
override
nonReentrant
onlyValidator
208: function executeBlocks(StoredBlockInfo[] calldata _blocksData) external nonReentrant onlyValidator {
221-225: function proveBlocks(
StoredBlockInfo calldata _prevBlock,
StoredBlockInfo[] calldata _committedBlocks,
ProofInput calldata _proof
) external nonReentrant onlyValidator {
336: function revertBlocks(uint256 _newLastBlock) external nonReentrant onlyValidator {
File: 2022-10-zksync/ethereum/contracts/zksync/facets/Governance.sol
45: function setValidator(address _validator, bool _active) external onlyGovernor {
54: function setL2BootloaderBytecodeHash(bytes32 _l2BootloaderBytecodeHash) external onlyGovernor {
69: function setL2DefaultAccountBytecodeHash(bytes32 _l2DefaultAccountBytecodeHash) external onlyGovernor {
84: function setPorterAvailability(bool _zkPorterIsAvailable) external onlyGovernor {
94: function setVerifier(Verifier _newVerifier) external onlyGovernor {
104: function setVerifierParams(VerifierParams calldata _newVerifierParams) external onlyGovernor {
File: 2022-10-zksync/ethereum/contracts/common/AllowList.sol
57: function setPublicAccess(address _target, bool _enable) external onlyOwner {
65: function setBatchPublicAccess(address[] calldata _targets, bool[] calldata _enables) external onlyOwner {
89-94: function setBatchPermissionToCall(
address[] calldata _callers,
address[] calldata _targets,
bytes4[] calldata _functionSigs,
bool[] calldata _enables
) external onlyOwner {
113-118: function setPermissionToCall(
address _caller,
address _target,
bytes4 _functionSig,
bool _enable
) external onlyOwner {
140: function setPendingOwner(address _newPendingOwner) external onlyOwner {
File: 2022-10-zksync/zksync/contracts/bridge/L2StandardERC20.sol
102: function bridgeMint(address _to, uint256 _amount) external override onlyBridge {
109: function bridgeBurn(address _from, uint256 _amount) external override onlyBridge {
[5] USING PRIVATE RATHER THAN PUBLIC FOR CONSTANTS, SAVES GAS
If needed, the value can be read from the verified contract source code. Savings are due to the compiler not having to create non-payable getter functions for deployment calldata, and not adding another entry to the method ID table
There are 37 instances of this issue:
File: 2022-10-zksync/ethereum/contracts/zksync/Config.sol
5: bytes32 constant EMPTY_STRING_KECCAK = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
9: uint256 constant L2_TO_L1_LOG_SERIALIZE_SIZE = 88;
12: uint256 constant L2_TO_L1_LOGS_COMMITMENT_BYTES = 4 + L2_TO_L1_LOG_SERIALIZE_SIZE * 512;
15: uint256 constant L2_TO_L1_LOG_MERKLE_TREE_HEIGHT = 9;
20: bytes32 constant L2_L1_LOGS_TREE_DEFAULT_LEAF_HASH =
0x72abee45b59e344af8a6e520241c4744aff26ed411f4c4b00f8af09adada43ba;
23: uint256 constant INITIAL_STORAGE_CHANGES_COMMITMENT_BYTES = 4 + 64 * 4896;
26: uint256 constant REPEATED_STORAGE_CHANGES_COMMITMENT_BYTES = 4 + 40 * 7787;
29: bytes32 constant DEFAULT_L2_LOGS_TREE_ROOT_HASH = bytes32(0);
32: address constant L2_TO_L1_MESSENGER = address(0x8008);
35: address constant L2_BOOTLOADER_ADDRESS = address(0x8001);
38: address constant L2_KNOWN_CODE_STORAGE_ADDRESS = address(0x8004);
41: address constant L2_SYSTEM_CONTEXT_ADDRESS = address(0x800b);
44: uint256 constant PRIORITY_OPERATION_L2_TX_TYPE = 255;
47: uint256 constant BLOCK_PERIOD = 13 seconds;
51: uint256 constant PRIORITY_EXPIRATION_PERIOD = 3 days;
54: uint256 constant PRIORITY_EXPIRATION = $(
60: uint256 constant UPGRADE_NOTICE_PERIOD = $$(defined(UPGRADE_NOTICE_PERIOD) ? UPGRADE_NOTICE_PERIOD : "14 days");
63: uint256 constant COMMIT_TIMESTAMP_NOT_OLDER = $$(
69: uint256 constant COMMIT_TIMESTAMP_APPROXIMATION_DELTA = $$(
74: uint256 constant INPUT_MASK = $$(~uint256(0) >> 8);
77: uint256 constant PRIORITY_TX_MAX_ERGS_LIMIT = 2097152;
80: uint256 constant SECURITY_COUNCIL_APPROVALS_FOR_EMERGENCY_UPGRADE = $$(
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L5
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L9
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L12
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L15
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L20
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L23
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L26
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L29
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L32
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L35
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L38
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L41
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L44
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L47
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L51
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L54
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L60
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L63
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L69
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L74
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L77
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol#L80
File: 2022-10-zksync/ethereum/contracts/zksync/libraries/Diamond.sol
10-11: bytes32 constant DIAMOND_INIT_SUCCESS_RETURN_VALUE =
0x33774e659306e47509050e97cb651e731180a42d458212294d30751925c551a2;
14: bytes32 constant DIAMOND_STORAGE_POSITION = 0xc8fcad8db84d3cc18b4c41d551ea0ee66dd599cde068d998e57d5e09332c131b;
File: 2022-10-zksync/ethereum/contracts/bridge/L1ERC20Bridge.sol
32: uint256 constant DEPOSIT_ERGS_LIMIT = 2097152;
36: uint256 constant DEPLOY_L2_BRIDGE_COUNTERPART_ERGS_LIMIT = 2097152;
File: 2022-10-zksync/ethereum/contracts/bridge/L1EthBridge.sol
26: uint256 constant DEPOSIT_ERGS_LIMIT = 2097152;
30: uint256 constant DEPLOY_L2_BRIDGE_COUNTERPART_ERGS_LIMIT = 2097152;
33: address constant CONVENTIONAL_ETH_ADDRESS = address(0);
File: 2022-10-zksync/ethereum/contracts/common/L2ContractHelper.sol
26: uint160 constant SYSTEM_CONTRACTS_OFFSET = 0x8000;
28: address constant BOOTLOADER_ADDRESS = address(SYSTEM_CONTRACTS_OFFSET + 0x01);
30: address constant DEPLOYER_SYSTEM_CONTRACT_ADDRESS = address(SYSTEM_CONTRACTS_OFFSET + 0x06);
34: address constant FORCE_DEPLOYER = address(SYSTEM_CONTRACTS_OFFSET + 0x07);
36: IL2Messenger constant L2_MESSENGER = IL2Messenger(address(SYSTEM_CONTRACTS_OFFSET + 0x08));
38: address constant VALUE_SIMULATOR_SYSTEM_CONTRACT_ADDRESS = address(SYSTEM_CONTRACTS_OFFSET + 0x09);
41: bytes32 constant CREATE2_PREFIX = keccak256("zksyncCreate2");
File: 2022-10-zksync/zksync/contracts/bridge/L2ETHBridge.sol
28: address constant CONVENTIONAL_ETH_ADDRESS = address(0);
[6] USE ASSEMBLY TO CHECK FOR ADDRESS(0) to save gas.
There are 8 instances of this issue:
File: 2022-10-zksync/ethereum/contracts/zksync/DiamondProxy.sol
29: require(facetAddress != address(0), "F");
File: 2022-10-zksync/ethereum/contracts/zksync/facets/Getters.sol
148: require(ds.selectorToFacet[_selector].facetAddress != address(0), "g2");
File: 2022-10-zksync/ethereum/contracts/zksync/libraries/Diamond.sol
126: require(_facet != address(0), "G");
150: require(_facet != address(0), "K");
156: require(oldFacet.facetAddress != address(0), "L");
176: require(oldFacet.facetAddress != address(0), "a2");
File: 2022-10-zksync/zksync/contracts/bridge/L2ERC20Bridge.sol
95: require(l1Token != address(0), "yh");
File: 2022-10-zksync/zksync/contracts/bridge/L2StandardERC20.sol
45: require(_l1Address != address(0), "in6");
[7] SPLITTING REQUIRE() STATEMENTS THAT USE && SAVES GAS
See this issue which describes the fact that there is a larger deployment gas cost, but with enough runtime calls, the change ends up being cheaper.
There are 2 instances of this issue:
File: 2022-10-zksync/ethereum/contracts/common/AllowList.sol
96-101: require(
callersLength == _targets.length &&
callersLength == _functionSigs.length &&
callersLength == _enables.length,
"yw"
);
File: 2022-10-zksync/ethereum/contracts/common/L2ContractHelper.sol
65: require(version == 1 && _bytecodeHash[1] == bytes1(0), "zf");
[8] DUPLICATED REQUIRE()/REVERT() CHECKS SHOULD BE REFACTORED TO A MODIFIER OR FUNCTION
Saves deployment cost
There are 2 instances of this issue:
File: 2022-10-zksync/ethereum/contracts/zksync/libraries/PriorityQueue.sol
64: require(!_queue.isEmpty(), "D");
72: require(!_queue.isEmpty(), "s");
[9] ++I/I++ SHOULD BE UNCHECKED{++I}/UNCHECKED{I++} WHEN IT IS NOT POSSIBLE FOR THEM TO OVERFLOW, AS IS THE CASE WHEN USED IN FOR- AND WHILE-LOOPS
The unchecked keyword is new in solidity 0.8.0,so this only applies to that version or higher, which these instances are. This saves 30-40 gas PER LOOP
There are 4 instances of this issue:
File: 2022-10-zksync/ethereum/contracts/zksync/libraries/Diamond.sol
94: for (uint256 i = 0; i < facetCutsLength; ++i) {
132: for (uint256 i = 0; i < selectorsLength; ++i) {
153: for (uint256 i = 0; i < selectorsLength; ++i) {
173: for (uint256 i = 0; i < selectorsLength; ++i) {