There are 2 instances of this issue
File: contracts/zksync/facets/DiamondCut.sol
29: s.diamondCutStorage.currentProposalId += 1;
File: contracts/zksync/libraries/Merkle.sol
34: _index /= 2;
Not inlining costs 20 to 40 gas because of two extra JUMP instructions and additional stack operations needed for function calls.
There are 10 instances of this issue
File: contracts/bridge/L1ERC20Bridge.sol
136: function _depositFunds(
149: function _getDepositL2Calldata(
164: function _getERC20Getters(address _token) internal view returns (bytes memory data) {
260: function _parseL2WithdrawalMessage(bytes memory _l2ToL1message)
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/bridge/L1EthBridge.sol
File: contracts/bridge/L1EthBridge.sol
113: function _getDepositL2Calldata(
214: function _parseL2WithdrawalMessage(bytes memory _message)
File: contracts/common/L2ContractHelper.sol
71: function bytecodeLen(bytes32 _bytecodeHash) internal pure returns (uint256 codeLengthInWords) {
File: contracts/zksync/facets/Executor.sol
23: function _commitOneBlock(StoredBlockInfo memory _previousBlock, CommitBlockInfo calldata _newBlock)
89: function _processL2Logs(CommitBlockInfo calldata _newBlock)
177: function _collectOperationsFromPriorityQueue(uint256 _nPriorityOps) internal returns (bytes32 concatHash) {
<x> * 2 is equivalent to <x> << 1 and <x> / 2 is the same as <x> >> 1. The MUL and DIV opcodes cost 5 gas, whereas SHL and SHR only cost 3 gas
There is 1 instance of this issue
File: contracts/zksync/libraries/Merkle.sol
34: _index /= 2;
There are 2 instances of this issue
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/common/AllowList.sol
File: contracts/common/AllowList.sol
96-101: require(
callersLength == _targets.length &&//@audit-info Splitting require() statements that use && saves gas
callersLength == _functionSigs.length &&
callersLength == _enables.length,
"yw"
);
File: contracts/common/L2ContractHelper.sol
65: require(version == 1 && _bytecodeHash[1] == bytes1(0), "zf");
Between solc 0.4.10 and 0.8.0, require() used REVERT (0xfd) opcode which refunded remaining gas on failure while assert() used INVALID (0xfe) opcode which consumed all the supplied gas..
require() should be used for checking error conditions on inputs and return values while assert() should be used for invariant checking (properly functioning code should never reach a failing assert statement, unless there is a bug in your contract you should fix).
From the current usage of assert, my guess is that they can be replaced with require, unless a Panic really is intended.
There is 1 instance of this issue
File: contracts/zksync/facets/DiamondCut.sol
16: assert(SECURITY_COUNCIL_APPROVALS_FOR_EMERGENCY_UPGRADE > 0);
In Solidity 0.8+, there’s a default overflow check on unsigned integers. It’s possible to uncheck this in for-loops and save some gas at each iteration, but at the cost of some code readability, as this uncheck cannot be made inline
Prior to Solidity 0.8.0, arithmetic operations would always wrap in case of under- or overflow leading to widespread use of libraries that introduce additional checks.
Since Solidity 0.8.0, all arithmetic operations revert on over- and underflow by default, thus making the use of these libraries unnecessary.
To obtain the previous behaviour, an unchecked block can be used
There are 4 instances of this issue
File: 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) {
G-07 IT COSTS MORE GAS TO INITIALIZE VARIABLES WITH THEIR DEFAULT VALUE THAN LETTING THE DEFAULT VALUE BE APPLIED
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/bridge/L1EthBridge.sol
File: contracts/bridge/L1EthBridge.sol
33: address constant CONVENTIONAL_ETH_ADDRESS = address(0);
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 9 instances of this issue
File: contracts/bridge/L1ERC20Bridge.sol
185: uint16 _l2TxNumberInBlock,
228: uint16 _l2TxNumberInBlock,
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/bridge/L1EthBridge.sol
File: contracts/bridge/L1EthBridge.sol
138: uint16 _l2TxNumberInBlock
185: uint16 _l2TxNumberInBlock
File: contracts/bridge/interfaces/IL1Bridge.sol
29: uint16 _l2TxNumberInBlock
36: uint16 _l2TxNumberInBlock
File: contracts/common/L2ContractHelper.sol
42: uint16 txNumberInBlock;
54: uint16 txNumberInBlock
File: contracts/bridge/L1ERC20Bridge.sol
29: uint8 private decimals_
Removing unused named returns variables can reduce gas usage (MSTOREs/MLOADs) and improve code clarity. To save gas and improve code quality: consider using only one of those.
There is 1 instance of this issue
File: contracts/zksync/facets/Executor.sol
26: returns (StoredBlockInfo memory storedNewBlock)
There is 1 instance of this issue
File: contracts/zksync/facets/Executor.sol
80: function _calculateBlockHash(StoredBlockInfo memory _previousBlock, CommitBlockInfo calldata _newBlock)
G-11 EXPRESSIONS FOR CONSTANT VALUES SUCH AS A CALL TO KECCAK256(), SHOULD USE IMMUTABLE RATHER THAN CONSTANT
There are 2 instances of this issue
https://github.com/code-423n4/2022-10-zksync/blob/main/ethereum/contracts/zksync/Config.sol
File: contracts/zksync/Config.sol
5: bytes32 constant EMPTY_STRING_KECCAK = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
File: contracts/common/L2ContractHelper.sol
24: bytes32 constant CREATE2_PREFIX = keccak256("zksyncCreate2");