Maia DAO - Ulysses - Rolezn's results

Disclaimer: Several Gas findings now contain an <b>[Enhanced]</b> tag which indicate findings that have enhanced details which include per-instance foundry test gas reports and its gas usage. While some of the instances may be mentioned in the automated report, however, this report provides accurate gas-based test reports in order to help prioritize specific changes that can significantly reduce gas usage.

GAS Summary<a name="GAS Summary">

Gas Optimizations

Total: 161 contexts over 11 issues

Gas Optimizations

<a href="#gas-summary">[GAS‑1]</a><a name="GAS&#x2011;1"> Use assembly in place of abi.decode to extract calldata values more efficiently

Instead of using abi.decode, we can use assembly to decode our desired calldata values directly. This will allow us to avoid decoding calldata values that we will not use.

For example, for a generic abi.decode call:

(bytes32 varA, bytes32 varB, uint256 varC, uint256 varD) = abi.decode(metadata, (bytes32, bytes32, uint256, uint256));

We can use the following assembly call to extract the relevant metadata:

        bytes32 varA;
        bytes32 varB;
        uint256 varC;
        uint256 varD;
        { // used to discard `data` variable and avoid extra stack manipulation
            bytes calldata data = metadata;
            assembly {
                varA := calldataload(add(data.offset, 0x00))
                varB := calldataload(add(data.offset, 0x20))
                varC := calldataload(add(data.offset, 0x40))
                varD := calldataload(add(data.offset, 0x60))
            }
        }

<ins>Proof Of Concept</ins>

File: ArbitrumCoreBranchRouter.sol

158: (address underlyingToken, uint256 minimumReservesRatio) = abi.decode(_data[1:], (address, uint256));

https://github.com/code-423n4/2023-09-maia/tree/main/src/ArbitrumCoreBranchRouter.sol#L158

File: CoreBranchRouter.sol

128: (address underlyingToken, uint256 minimumReservesRatio) = abi.decode(_params[1:], (address, uint256));

https://github.com/code-423n4/2023-09-maia/tree/main/src/CoreBranchRouter.sol#L128

<a href="#gas-summary">[GAS‑2]</a><a name="GAS&#x2011;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 Each operation involving a uint8 costs an extra 22-28 gas (depending on whether the other operand is also a variable of type uint8) as compared to ones involving uint256, due to the compiler having to clear the higher bits of the memory word before operating on the uint8, as well as the associated stack operations of doing so. Use a larger size then downcast where needed

<ins>Proof Of Concept</ins>

Optimize to the following in order to decrease a total of $\textcolor{green}{\textsf{-264017}}$ gas usage (includes proof of forge test runs):

uint256 public immutable localChainId;

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L40

uint256 public immutable localChainId;

https://github.com/code-423n4/2023-09-maia/tree/main/src/ArbitrumBranchPort.sol#L22

uint256 public immutable localChainId;

https://github.com/code-423n4/2023-09-maia/tree/main/src/factories/ERC20hTokenBranchFactory.sol#L14

uint256 numberOfAssets;

https://github.com/code-423n4/2023-09-maia/tree/main/src/interfaces/BridgeAgentStructs.sol#L90

</details>

<ins>Forge test</ins>

Running forge test comparison report:

<details>

Ran 9 test suites: 140 tests passed, 0 failed, 0 skipped (140 total tests) testAddStrategyToken() (gas: -12 (-0.001%))

testManageTwoDayLimits() (gas: -24 (-0.001%))

testReplenishAsUser() (gas: -24 (-0.001%))

testReplenishAsStrategyNotEnoughDebtToRepay() (gas: -24 (-0.001%))

testManage() (gas: -24 (-0.001%))

testReplenishAsStrategy() (gas: -24 (-0.001%))

testRetrySettlementNoFallback() (gas: -154 (-0.001%))

testManageExceedsDailyLimit() (gas: -24 (-0.001%))

testRetryDeposit() (gas: -136 (-0.001%))

testRetrySettlementTriggerFallback() (gas: -160 (-0.001%))

testRetryDepositNotEnoughGasForSettlement() (gas: -136 (-0.001%))

testManageExceedsMinimumReserves() (gas: -24 (-0.001%))

testRedeemSettlement() (gas: -160 (-0.001%))

testRetrySettlement() (gas: -154 (-0.001%))

testAddPortStrategy() (gas: -24 (-0.001%))

testRetrieveSettlement() (gas: -172 (-0.001%))

testCallOutWithDepositWrongCalldataForRootFallbackMode() (gas: -118 (-0.001%))

testRedeemDepositAfterFallback() (gas: -118 (-0.001%))

testRetrieveDeposit() (gas: -129 (-0.001%))

testRedeemDepositAfterRetrieve() (gas: -129 (-0.001%))

testAddLocalToken() (gas: -33 (-0.001%)) testRemoveStrategyToken() (gas: -24 (-0.001%))

testMulticallNoOutputNoDeposit() (gas: -1 (-0.001%))

testCallOutWithDepositNotEnoughGasForRootFallbackMode() (gas: -123 (-0.001%))

testCallOutWithDepositSuccess() (gas: -123 (-0.001%))

testCallOutWithDepositWrongCalldataForRootRetryMode() (gas: -124 (-0.001%))

testCallOutWithDepositNotEnoughGasForRootRetryMode() (gas: -123 (-0.001%))

testFuzzExecuteWithSettlement(address,uint256,uint256,uint16) (gas: -22 (-0.001%)) testAddGlobalTokenFork() (gas: -84 (-0.001%))

testFuzzFallbackClearDepositRedeem(address,uint256,uint256,uint16) (gas: -22 (-0.001%)) testCallOutWithDepositArbtirum() (gas: -130 (-0.001%))

testAddLocalTokenArbitrum() (gas: -117 (-0.001%))

testAddPortStrategyNotToken() (gas: -12 (-0.001%))

testAddStrategyTokenInvalidMinReserve() (gas: -12 (-0.001%))

testAddLocalToken() (gas: -33 (-0.001%)) testCallOutWithDeposit() (gas: -46 (-0.002%))

testCallOutWithDepositExecutionFailed() (gas: -40 (-0.002%))

testMulticallSignedSingleOutputDepositMultiple() (gas: 34 (0.002%)) testMulticallSignedSingleOutputDepositMultiple() (gas: 34 (0.002%)) testFuzzExecuteWithSettlementMultiple(uint256,uint256,uint256,uint256,uint16) (gas: -76 (-0.002%)) testMulticallSignedMultipleOutputDepositMultiple() (gas: 40 (0.002%)) testCallOutWithDeposit() (gas: -142 (-0.002%))

testMulticallSignedMultipleOutputDepositMultiple() (gas: 40 (0.002%)) testRetrySettlement() (gas: -172 (-0.003%))

testRedeemSettlement() (gas: -166 (-0.003%))

testAddLocalTokenArbitrum() (gas: -33 (-0.003%))

testAddGlobalToken() (gas: -96 (-0.003%))

testMulticallSignedNoOutputDepositMultiple() (gas: 46 (0.003%)) testAddLocalTokenArbitrum() (gas: -129 (-0.003%))

testAddBridgeAgentFactory() (gas: -24 (-0.003%))

testAddLocalToken() (gas: -33 (-0.003%)) testMulticallSignedNoOutputDepositMultiple() (gas: 46 (0.003%)) testAddLocalToken() (gas: -33 (-0.003%)) testDepositToPort() (gas: -39 (-0.003%))

testAddLocalTokenFromArbitrum() (gas: -33 (-0.003%))

testAddLocalTokenNotEnoughGas() (gas: -33 (-0.003%))

testMulticallSignedNoOutputDepositSingleNative() (gas: -64 (-0.003%))

testMulticallSignedNoOutputDepositSingle() (gas: -64 (-0.003%))

testMulticallSignedMultipleOutputDepositSingle() (gas: -64 (-0.003%)) testMulticallSignedMultipleOutputNoDeposit() (gas: -64 (-0.003%)) testRetryTwoSettlements() (gas: -215 (-0.003%))

testMulticallMultipleOutputNoDeposit() (gas: -64 (-0.003%)) testWithdrawFromPortUnknownGlobal() (gas: -42 (-0.003%))

testRedeemTwoSettlements() (gas: -203 (-0.003%))

testMulticallSignedMultipleOutputDepositSingle() (gas: -64 (-0.003%)) testMulticallSignedNoOutputDepositSingle() (gas: -52 (-0.003%)) testMulticallSignedMultipleOutputNoDeposit() (gas: -64 (-0.003%)) testMulticallMultipleOutputNoDeposit() (gas: -64 (-0.003%)) testFallbackClearDepositRedeemDouble() (gas: -18 (-0.003%))

testMulticallSignedSingleOutputDepositSingle() (gas: -64 (-0.003%)) testFallbackClearDepositRedeemAlreadyRedeemed() (gas: -18 (-0.003%))

testFallbackClearDepositRedeemSuccess() (gas: -18 (-0.003%))

testMulticallSignedNoOutputDepositSingle() (gas: -52 (-0.003%)) testMulticallSignedSingleOutputNoDeposit() (gas: -64 (-0.003%))

testMulticallSingleOutputNoDeposit() (gas: -64 (-0.003%))

testWithdrawFromPort() (gas: -45 (-0.003%))

testMulticallSignedSingleOutputDepositSingle() (gas: -64 (-0.003%)) testMulticallMismatchTokens() (gas: -75 (-0.003%))

testMulticallSignedSingleOutputNoDeposit() (gas: -64 (-0.004%))

testMulticallSingleOutputNoDeposit() (gas: -64 (-0.004%))

testMulticallNoOutputNoDeposit() (gas: -52 (-0.004%)) testAddGlobalToken() (gas: -45 (-0.004%))

testAddGlobalTokenNotEnoughGas() (gas: -45 (-0.004%))

testRetryDepositFailCanAlwaysRetry() (gas: -22 (-0.004%))

testMulticallNoCodeInTarget() (gas: -58 (-0.004%)) testMulticallNoOutputNoDeposit() (gas: -52 (-0.004%)) testRetryDeposit() (gas: -22 (-0.004%))

testRetryDepositFailNotOwner() (gas: -22 (-0.004%))

testSetLocalToken() (gas: -51 (-0.004%))

testCallOutWithDeposit(address,uint256) (gas: -22 (-0.004%)) testCallOutWithDeposit() (gas: -22 (-0.004%))

testCallOutSignedAndBridge(address,uint256) (gas: -22 (-0.004%)) testMulticallNoCodeInTarget() (gas: -58 (-0.004%)) testRemoveBridgeAgent() (gas: -34 (-0.004%))

testAddGlobalTokenAlreadyAdded() (gas: -57 (-0.004%))

testAddGlobalToken() (gas: -57 (-0.005%))

testSetLocalToken() (gas: -63 (-0.005%))

testRemoveBridgeAgentFactory() (gas: -48 (-0.005%))

testAddLocalTokenAlreadyAdded() (gas: -66 (-0.005%))

testDepositToPortUnrecognized() (gas: -6 (-0.005%))

testAddStrategyToken() (gas: -24 (-0.008%))

testAddPortStrategyNotToken() (gas: -24 (-0.010%))

testAddPortStrategy() (gas: -48 (-0.010%))

testAddStrategyTokenInvalidMinReserve() (gas: -24 (-0.011%))

testMulticallTwoTimesMessage() (gas: -13 (-0.011%))

testRemoveStrategyToken() (gas: -48 (-0.013%))

testRemoveBridgeAgent() (gas: -46 (-0.022%))

testAddLocalTokenArbitrumFailedIsGlobal() (gas: -33 (-0.030%))

testAddBridgeAgentWrongBranchFactory() (gas: -5224 (-0.071%))

testRemoveBridgeAgentFactory() (gas: -4636 (-0.074%))

testAddBridgeAgentWrongRootFactory() (gas: -5256 (-0.075%))

testAddBridgeAgentWrongRootFactory() (gas: -9848 (-0.077%))

testFuzzReadDepositData(uint32,uint256,uint256,uint256,uint256) (gas: -54 (-0.080%)) testAddLocalTokenNewCore() (gas: -18512 (-0.083%))

testAddBridgeAgentWrongBranchFactory() (gas: -5232 (-0.084%))

testAddBridgeAgentFactory() (gas: -4624 (-0.084%))

testAddTwoBridgeAgentFactories() (gas: -9248 (-0.085%))

testAddBridgeAgentTwoTimes() (gas: -12237 (-0.086%))

testAddBridgeAgentNotApproved() (gas: -5212 (-0.087%))

testAddBridgeAgentNotManager() (gas: -5212 (-0.088%))

testAddBridgeAgentNotApproved() (gas: -5208 (-0.088%))

testAddBridgeAgentNotManager() (gas: -5208 (-0.088%))

testAddBridgeAgentNewFactory() (gas: -15061 (-0.088%))

testAddBridgeAgentAlreadyAdded() (gas: -12437 (-0.097%))

testAddBridgeAgentSimple() (gas: -12437 (-0.097%))

testAddBridgeAgentTwice() (gas: -12245 (-0.099%))

testSyncNewCoreBranchRouter() (gas: -18479 (-0.102%))

testSetCoreRootRouter() (gas: -18479 (-0.102%))

testSetBranchRouter() (gas: -18479 (-0.102%))

testAddBridgeAgentFactoryNotRootFactory() (gas: -4617 (-0.103%))

testAddBridgeAgentAlreadyAdded() (gas: -12445 (-0.114%))

testAddBridgeAgent() (gas: -12445 (-0.114%))

testAddBridgeAgentArbitrum() (gas: -12430 (-0.114%))

testAddBridgeAgentArbitrum() (gas: -12426 (-0.115%))

Overall gas change: $\textcolor{green}{\textsf{-264017}}$ (-0.037%)

</details>

<a href="#gas-summary">[GAS‑3]</a><a name="GAS&#x2011;3"> Use do while loops instead of for loops

A do while loop will cost less gas since the condition is not being checked for the first iteration.

<ins>Proof Of Concept</ins>

Optimize to the following in order to decrease a total of $\textcolor{green}{\textsf{-6415}}$ gas usage (includes proof of forge test runs):

File: BranchPort.sol

246: function bridgeInMultiple

do {
        // Check if hTokens are being bridged in
        if (_amounts[i] - _deposits[i] > 0) {
            unchecked {
                _bridgeIn(_recipient, _localAddresses[i], _amounts[i] - _deposits[i]);
            }
        }

        // Check if underlying tokens are being cleared
        if (_deposits[i] > 0) {
            withdraw(_recipient, _underlyingAddresses[i], _deposits[i]);
        }

        unchecked {
            ++i;
        }
    } while (i < length);

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L247

<ins>Forge test</ins>

Running forge test comparison report:

<details> Ran 9 test suites: 140 tests passed, 0 failed, 0 skipped (140 total tests)

testRetryDepositNotEnoughGasForSettlement() (gas: -23 (-0.000%))

testRetrieveDeposit() (gas: -23 (-0.000%))

testCallOutWithDepositWrongCalldataForRootFallbackMode() (gas: -23 (-0.000%))

testCallOutWithDepositWrongCalldataForRootRetryMode() (gas: -23 (-0.000%))

testCallOutWithDepositNotEnoughGasForRootFallbackMode() (gas: -23 (-0.000%))

testCallOutWithDepositSuccess() (gas: -23 (-0.000%))

testCallOutWithDepositNotEnoughGasForRootRetryMode() (gas: -23 (-0.000%))

testAddBridgeAgentWrongBranchFactory() (gas: -16 (-0.000%))

testAddBridgeAgentWrongBranchFactory() (gas: -16 (-0.000%))

testRetrieveSettlement() (gas: -57 (-0.000%))

testRetrySettlementTriggerFallback() (gas: -57 (-0.000%))

testRedeemSettlement() (gas: -57 (-0.000%))

testRetrySettlementNoFallback() (gas: -57 (-0.000%))

testRetrySettlement() (gas: -57 (-0.000%))

testRedeemDepositAfterRetrieve() (gas: -45 (-0.000%))

testRetryDeposit() (gas: -57 (-0.000%))

testRedeemDepositAfterFallback() (gas: -45 (-0.000%))

testRedeemSettlement() (gas: -23 (-0.000%))

testAddBridgeAgentArbitrum() (gas: -53 (-0.000%))

testAddBridgeAgentArbitrum() (gas: -53 (-0.000%))

testAddBridgeAgentTwoTimes() (gas: -73 (-0.001%))

testAddLocalTokenNewCore() (gas: -115 (-0.001%))

testFuzzExecuteWithSettlementMultiple(uint256,uint256,uint256,uint256,uint16) (gas: -23 (-0.001%))

testAddBridgeAgentAlreadyAdded() (gas: -73 (-0.001%))

testAddBridgeAgentSimple() (gas: -73 (-0.001%))

testAddBridgeAgentTwice() (gas: -73 (-0.001%))

testCallOutWithDepositArbtirum() (gas: -69 (-0.001%))

testSyncNewCoreBranchRouter() (gas: -115 (-0.001%))

testSetCoreRootRouter() (gas: -115 (-0.001%))

testSetBranchRouter() (gas: -115 (-0.001%))

testAddBridgeAgentNewFactory() (gas: -112 (-0.001%))

testAddBridgeAgentAlreadyAdded() (gas: -73 (-0.001%))

testAddBridgeAgent() (gas: -73 (-0.001%))

testRedeemTwoSettlements() (gas: -46 (-0.001%))

testAddBridgeAgentWrongRootFactory() (gas: -90 (-0.001%))

testRetrySettlement() (gas: -57 (-0.001%))

testCallOutWithDepositExecutionFailed() (gas: -23 (-0.001%))

testAddBridgeAgentFactory() (gas: -55 (-0.001%))

testCallOutWithDeposit() (gas: -69 (-0.001%))

testAddTwoBridgeAgentFactories() (gas: -126 (-0.001%))

testAddBridgeAgentWrongRootFactory() (gas: -90 (-0.001%))

testRetryTwoSettlements() (gas: -114 (-0.002%))

testRemoveBridgeAgentFactory() (gas: -139 (-0.002%))

testCallOutWithDeposit() (gas: -69 (-0.002%))

testAddStrategyToken() (gas: -60 (-0.003%))

testFuzzExecuteWithSettlement(address,uint256,uint256,uint16) (gas: -79 (-0.004%))

testRetryDepositFailCanAlwaysRetry() (gas: -23 (-0.004%))

testRetryDeposit() (gas: -23 (-0.004%))

testAddPortStrategy() (gas: -114 (-0.004%))

testRetryDepositFailNotOwner() (gas: -23 (-0.004%))

testCallOutWithDeposit(address,uint256) (gas: -23 (-0.004%))

testCallOutWithDeposit() (gas: -23 (-0.004%))

testCallOutSignedAndBridge(address,uint256) (gas: -23 (-0.004%))

testFuzzFallbackClearDepositRedeem(address,uint256,uint256,uint16) (gas: -79 (-0.004%))

testRemoveStrategyToken() (gas: -111 (-0.004%))

testManageExceedsMinimumReserves() (gas: -132 (-0.004%))

testAddPortStrategyNotToken() (gas: -46 (-0.005%))

testManageExceedsDailyLimit() (gas: -160 (-0.005%))

testAddStrategyTokenInvalidMinReserve() (gas: -52 (-0.006%))

testRemoveBridgeAgent() (gas: -51 (-0.006%))

testAddBridgeAgentFactory() (gas: -55 (-0.006%))

testFallbackClearDepositRedeemDouble() (gas: -36 (-0.007%))

testFallbackClearDepositRedeemAlreadyRedeemed() (gas: -36 (-0.007%))

testFallbackClearDepositRedeemSuccess() (gas: -36 (-0.007%))

testManage() (gas: -207 (-0.007%))

testReplenishAsStrategyNotEnoughDebtToRepay() (gas: -233 (-0.008%))

testDepositToPort() (gas: -107 (-0.008%))

testManageTwoDayLimits() (gas: -300 (-0.010%))

testReplenishAsStrategy() (gas: -307 (-0.010%))

testReplenishAsUser() (gas: -322 (-0.010%))

testWithdrawFromPortUnknownGlobal() (gas: -158 (-0.011%))

testRemoveBridgeAgentFactory() (gas: -139 (-0.015%))

testWithdrawFromPort() (gas: -223 (-0.017%))

testAddPortStrategyNotToken() (gas: -46 (-0.019%))

testAddStrategyToken() (gas: -60 (-0.020%))

testAddStrategyTokenInvalidMinReserve() (gas: -52 (-0.024%))

testAddPortStrategy() (gas: -114 (-0.024%))

testRemoveBridgeAgent() (gas: -51 (-0.024%))

testRemoveStrategyToken() (gas: -111 (-0.029%))

testDepositToPortUnrecognized() (gas: -66 (-0.060%))

Overall gas change: $\textcolor{green}{\textsf{-6415}}$ (-0.001%)

</details>

<a href="#gas-summary">[GAS‑4]</a><a name="GAS&#x2011;4"> <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<N> (3 gas), and gets rid of the extra DUP<N> needed to store the stack offset

<ins>Proof Of Concept</ins>

Note: While the instances may be present in the automated findings, it is important to note that the automated findings also contain instances that will <b>increase</b> that gas cost. Hence, in order to provide actual valid instances, these are the only findings that will specifically <b>decrease</b> the gas usage

Optimize to the following in order to decrease a total of $\textcolor{green}{\textsf{-210040}}$ gas usage (includes proof of forge test runs):

uint256 arrayLoopLength = outputTokens.length;
for (uint256 i = 0; i < arrayLoopLength;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L557

uint256 arrayLoopLength = hTokens.length;
for (uint256 i = 0; i < arrayLoopLength;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L1070

</details>

<ins>Forge test</ins>

Running forge test comparison report:

<details>

Ran 9 test suites: 140 tests passed, 0 failed, 0 skipped (140 total tests) testRetrieveDeposit() (gas: -18 (-0.000%))

testRedeemDepositAfterRetrieve() (gas: -18 (-0.000%))

testCallOutWithDepositWrongCalldataForRootFallbackMode() (gas: -18 (-0.000%))

testRedeemDepositAfterFallback() (gas: -18 (-0.000%))

testCallOutWithDepositWrongCalldataForRootRetryMode() (gas: -18 (-0.000%))

testCallOutWithDepositNotEnoughGasForRootFallbackMode() (gas: -18 (-0.000%))

testCallOutWithDepositSuccess() (gas: -18 (-0.000%))

testCallOutWithDepositNotEnoughGasForRootRetryMode() (gas: -18 (-0.000%))

testCallOutWithDepositArbtirum() (gas: -18 (-0.000%))

testRetryDeposit() (gas: -36 (-0.000%))

testRetryDepositNotEnoughGasForSettlement() (gas: -36 (-0.000%))

testRetrieveSettlement() (gas: -54 (-0.000%))

testRetrySettlementTriggerFallback() (gas: -54 (-0.000%))

testRedeemSettlement() (gas: -54 (-0.000%))

testRetrySettlementNoFallback() (gas: -54 (-0.000%))

testRetrySettlement() (gas: -54 (-0.000%))

testMulticallSignedMultipleOutputDepositSingle() (gas: -22 (-0.001%)) testMulticallSignedMultipleOutputNoDeposit() (gas: -22 (-0.001%)) testMulticallMultipleOutputNoDeposit() (gas: -22 (-0.001%)) testMulticallSignedMultipleOutputDepositSingle() (gas: -22 (-0.001%)) testMulticallSignedMultipleOutputNoDeposit() (gas: -22 (-0.001%)) testMulticallMultipleOutputNoDeposit() (gas: -22 (-0.001%)) testAddLocalTokenNewCore() (gas: -6040 (-0.027%))

testSyncNewCoreBranchRouter() (gas: -6040 (-0.033%))

testSetCoreRootRouter() (gas: -6040 (-0.033%))

testSetBranchRouter() (gas: -6040 (-0.033%))

testAddBridgeAgentAlreadyAdded() (gas: -7649 (-0.059%))

testAddBridgeAgentSimple() (gas: -7649 (-0.059%))

testAddBridgeAgentTwoTimes() (gas: -9266 (-0.065%))

testAddBridgeAgentAlreadyAdded() (gas: -7653 (-0.070%))

testAddBridgeAgent() (gas: -7653 (-0.070%))

testAddBridgeAgentArbitrum() (gas: -7649 (-0.070%))

testAddBridgeAgentArbitrum() (gas: -7653 (-0.071%))

testAddBridgeAgentTwice() (gas: -9262 (-0.075%))

testAddBridgeAgentNewFactory() (gas: -15069 (-0.088%))

testAddBridgeAgentWrongBranchFactory() (gas: -7649 (-0.104%))

testAddBridgeAgentWrongRootFactory() (gas: -7653 (-0.109%))

testAddBridgeAgentWrongRootFactory() (gas: -15069 (-0.118%))

testRemoveBridgeAgentFactory() (gas: -7420 (-0.119%))

testAddBridgeAgentWrongBranchFactory() (gas: -7653 (-0.123%))

testAddBridgeAgentNotApproved() (gas: -7653 (-0.128%))

testAddBridgeAgentNotManager() (gas: -7653 (-0.129%)) testAddBridgeAgentNotApproved() (gas: -7653 (-0.129%))

testAddBridgeAgentNotManager() (gas: -7653 (-0.129%)) testAddBridgeAgentFactory() (gas: -7420 (-0.135%))

testAddTwoBridgeAgentFactories() (gas: -14840 (-0.137%))

testAddBridgeAgentFactoryNotRootFactory() (gas: -7425 (-0.165%))

Overall gas change: $\textcolor{green}{\textsf{-210040}}$ (-0.029%)

</details>

<a href="#gas-summary">[GAS‑5]</a><a name="GAS&#x2011;5"> Using XOR (^) and AND (&) bitwise equivalents

Given 4 variables a, b, c and d represented as such:

0 0 0 0 0 1 1 0 <- a
0 1 1 0 0 1 1 0 <- b
0 0 0 0 0 0 0 0 <- c
1 1 1 1 1 1 1 1 <- d

To have a == b means that every 0 and 1 match on both variables. Meaning that a XOR (operator ^) would evaluate to 0 ((a ^ b) == 0), as it excludes by definition any equalities.Now, if a != b, this means that there’s at least somewhere a 1 and a 0 not matching between a and b, making (a ^ b) != 0.Both formulas are logically equivalent and using the XOR bitwise operator costs actually the same amount of gas.However, it is much cheaper to use the bitwise OR operator (|) than comparing the truthy or falsy values.These are logically equivalent too, as the OR bitwise operator (|) would result in a 1 somewhere if any value is not 0 between the XOR (^) statements, meaning if any XOR (^) statement verifies that its arguments are different.

<ins>Proof Of Concept</ins>

<details>

File: BranchBridgeAgent.sol

127: _lzEndpointAddress != address(0) || _rootChainId == _localChainId,

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L127

File: BranchBridgeAgent.sol

412: if (payload.length == 0) revert DepositRetryUnavailableUseCallout();

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L412

File: BranchBridgeAgent.sol

439: if (deposit.status == STATUS_SUCCESS) revert DepositRedeemUnavailable();

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L439

File: BranchBridgeAgent.sol

440: if (deposit.owner == address(0)) revert DepositRedeemUnavailable();

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L440

File: BranchBridgeAgent.sol

599: if (flag == 0x00) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L599

File: BranchBridgeAgent.sol

616: } else if (flag == 0x01) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L616

File: BranchBridgeAgent.sol

638: } else if (flag == 0x02) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L638

File: BranchBridgeAgent.sol

663: } else if (flag == 0x03) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L663

File: BranchBridgeAgent.sol

681: } else if (flag == 0x04) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L681

File: CoreRootRouter.sol

278: require(msg.sender == rootPortAddress, "Only root port can call");

https://github.com/code-423n4/2023-09-maia/tree/main/src/CoreRootRouter.sol#L278

File: CoreRootRouter.sol

307: if (funcId == 0x02) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/CoreRootRouter.sol#L307

File: CoreRootRouter.sol

314: } else if (funcId == 0x03) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/CoreRootRouter.sol#L314

File: CoreRootRouter.sol

320: } else if (funcId == 0x04) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/CoreRootRouter.sol#L320

File: CoreRootRouter.sol

337: if (funcId == 0x01) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/CoreRootRouter.sol#L337

File: CoreRootRouter.sol

412: if (_dstChainId == rootChainId) revert InvalidChainId();

https://github.com/code-423n4/2023-09-maia/tree/main/src/CoreRootRouter.sol#L412

File: CoreRootRouter.sol

470: newToken, (_srcChainId == rootChainId) ? newToken : _localAddress, _underlyingAddress, _srcChainId

https://github.com/code-423n4/2023-09-maia/tree/main/src/CoreRootRouter.sol#L470

File: MulticallRootRouter.sol

142: if (funcId == 0x01) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L142

File: MulticallRootRouter.sol

150: } else if (funcId == 0x02) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L150

File: MulticallRootRouter.sol

174: } else if (funcId == 0x03) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L174

File: MulticallRootRouter.sol

234: if (funcId == 0x01) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L234

File: MulticallRootRouter.sol

242: } else if (funcId == 0x02) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L242

File: MulticallRootRouter.sol

265: } else if (funcId == 0x03) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L265

File: MulticallRootRouter.sol

323: if (funcId == 0x01) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L323

File: MulticallRootRouter.sol

331: } else if (funcId == 0x02) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L331

File: MulticallRootRouter.sol

354: } else if (funcId == 0x03) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L354

File: MulticallRootRouter.sol

411: if (funcId == 0x01) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L411

File: MulticallRootRouter.sol

419: } else if (funcId == 0x02) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L419

File: MulticallRootRouter.sol

442: } else if (funcId == 0x03) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L442

File: BranchPort.sol

123: require(coreBranchRouterAddress == address(0), "Contract already initialized");

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L123

File: BranchPort.sol

181: require(ERC20(_token).balanceOf(address(this)) - currBalance == _amount, "Port Strategy Withdraw Failed");

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L181

File: BranchPort.sol

214: ERC20(_token).balanceOf(address(this)) - currBalance == amountToWithdraw, "Port Strategy Withdraw Failed"

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L214

File: RootPort.sol

245: if (_globalAddress == address(0)) revert InvalidGlobalAddress();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L245

File: RootPort.sol

246: if (_localAddress == address(0)) revert InvalidLocalAddress();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L246

File: RootPort.sol

247: if (_underlyingAddress == address(0)) revert InvalidUnderlyingAddress();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L247

File: RootPort.sol

264: if (_localAddress == address(0)) revert InvalidLocalAddress();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L264

File: RootPort.sol

360: if (_user == address(0)) revert InvalidUserAddress();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L360

File: RootPort.sol

510: if (_coreRootRouter == address(0)) revert InvalidCoreRootRouter();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L510

File: RootPort.sol

511: if (_coreRootBridgeAgent == address(0)) revert InvalidCoreRootBridgeAgent();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L511

File: RootPort.sol

528: if (_coreBranchRouter == address(0)) revert InvalidCoreBranchRouter();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L528

File: RootPort.sol

529: if (_coreBranchBridgeAgent == address(0)) revert InvalidCoreBrancBridgeAgent();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L529

File: RootPort.sol

544: if (_coreBranchRouter == address(0)) revert InvalidCoreBranchRouter();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L544

File: RootPort.sol

545: if (_coreBranchBridgeAgent == address(0)) revert InvalidCoreBrancBridgeAgent();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L545

File: RootBridgeAgent.sol

244: if (settlementReference.owner == address(0)) revert SettlementRetryUnavailable();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L244

File: RootBridgeAgent.sol

282: if (settlementOwner == address(0)) revert SettlementRetrieveUnavailable();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L282

File: RootBridgeAgent.sol

307: if (settlement.status == STATUS_SUCCESS) revert SettlementRedeemUnavailable();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L307

File: RootBridgeAgent.sol

308: if (settlementOwner == address(0)) revert SettlementRedeemUnavailable();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L308

File: RootBridgeAgent.sol

430: if (!success) if (msg.sender == getBranchBridgeAgent[localChainId]) revert ExecutionFailure();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L430

File: RootBridgeAgent.sol

577: } else if (_payload[0] & 0x7F == 0x05) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L577

File: RootBridgeAgent.sol

617: } else if (_payload[0] & 0x7F == 0x06) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L617

File: RootBridgeAgent.sol

657: } else if (_payload[0] & 0x7F == 0x07) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L657

File: RootBridgeAgent.sol

670: if (settlementReference.owner == address(0)) revert SettlementRetryUnavailable();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L670

File: RootBridgeAgent.sol

818: if (callee == address(0)) revert UnrecognizedBridgeAgent();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L818

File: RootBridgeAgent.sol

871: if (_hTokens.length == 0) revert SettlementRetryUnavailableUseCallout();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L871

File: RootBridgeAgent.sol

877: if (_hTokens.length == 1) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L877

File: RootBridgeAgent.sol

910: if (callee == address(0)) revert UnrecognizedBridgeAgent();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L910

File: RootBridgeAgent.sol

1141: if (_amount == 0 && _deposit == 0) revert InvalidInputParams();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L1141

File: RootBridgeAgent.sol

1145: if (_localAddress == address(0)) revert UnrecognizedLocalAddress();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L1145

File: RootBridgeAgent.sol

1146: if (_underlyingAddress == address(0)) if (_deposit > 0) revert UnrecognizedUnderlyingAddress();

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L1146

File: ArbitrumBranchPort.sol

63: if (_globalToken == address(0)) revert UnknownGlobalToken();

https://github.com/code-423n4/2023-09-maia/tree/main/src/ArbitrumBranchPort.sol#L63

File: ArbitrumBranchPort.sol

90: if (_underlyingAddress == address(0)) revert UnknownUnderlyingToken();

https://github.com/code-423n4/2023-09-maia/tree/main/src/ArbitrumBranchPort.sol#L90

File: BranchBridgeAgentFactory.sol

121: msg.sender == localCoreBranchRouterAddress, "Only the Core Branch Router can create a new Bridge Agent."

https://github.com/code-423n4/2023-09-maia/tree/main/src/factories/BranchBridgeAgentFactory.sol#L121

File: BranchBridgeAgentFactory.sol

124: _rootBridgeAgentFactoryAddress == rootBridgeAgentFactoryAddress,

https://github.com/code-423n4/2023-09-maia/tree/main/src/factories/BranchBridgeAgentFactory.sol#L124

File: ArbitrumBranchBridgeAgentFactory.sol

85: msg.sender == localCoreBranchRouterAddress, "Only the Core Branch Router can create a new Bridge Agent."

https://github.com/code-423n4/2023-09-maia/tree/main/src/factories/ArbitrumBranchBridgeAgentFactory.sol#L85

File: ArbitrumBranchBridgeAgentFactory.sol

88: _rootBridgeAgentFactoryAddress == rootBridgeAgentFactoryAddress,

https://github.com/code-423n4/2023-09-maia/tree/main/src/factories/ArbitrumBranchBridgeAgentFactory.sol#L88

</details>

Test Code

contract GasTest is DSTest {
    Contract0 c0;
    Contract1 c1;
    function setUp() public {
        c0 = new Contract0();
        c1 = new Contract1();
    }
    function testGas() public {
        c0.not_optimized(1,2);
        c1.optimized(1,2);
    }
}

contract Contract0 {
    function not_optimized(uint8 a,uint8 b) public returns(bool){
        return ((a==1) || (b==1));
    }
}

contract Contract1 {
    function optimized(uint8 a,uint8 b) public returns(bool){
        return ((a ^ 1) & (b ^ 1)) == 0;
    }
}

Gas Test Report

<a href="#gas-summary">[GAS‑6]</a><a name="GAS&#x2011;6"> address(this) can be stored in state variable that will ultimately cost less, than every time calculating this, specifically when it used multiple times in a contract

<ins>Proof Of Concept</ins>

<details>

File: BranchBridgeAgent.sol

142: rootBridgeAgentPath = abi.encodePacked(_rootBridgeAgentAddress, address(this));

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L142

File: BranchBridgeAgent.sol

168: address(this),

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L168

File: BranchBridgeAgent.sol

579: address(this).excessivelySafeCall(

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L579

File: BranchBridgeAgent.sol

737: (bool success,) = bridgeAgentExecutorAddress.call{value: address(this).balance}(_calldata);

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L737

File: BranchBridgeAgent.sol

787: ILayerZeroEndpoint(lzEndpointAddress).send{value: address(this).balance}(

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L787

File: BranchBridgeAgent.sol

938: if (msg.sender != address(this)) revert LayerZeroUnauthorizedEndpoint();

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L938

File: ArbitrumBranchBridgeAgent.sol

126: if (msg.sender != address(this)) revert LayerZeroUnauthorizedEndpoint();

https://github.com/code-423n4/2023-09-maia/tree/main/src/ArbitrumBranchBridgeAgent.sol#L126

File: VirtualAccount.sol

62: ERC721(_token).transferFrom(address(this), msg.sender, _tokenId);

https://github.com/code-423n4/2023-09-maia/tree/main/src/VirtualAccount.sol#L62

File: BranchPort.sol

193: uint256 currBalance = ERC20(_token).balanceOf(address(this));

178: IPortStrategy(msg.sender).withdraw(address(this), _token, _amount);

181: require(ERC20(_token).balanceOf(address(this)) - currBalance == _amount, "Port Strategy Withdraw Failed");

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L193

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L178

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L181

File: BranchPort.sol

193: uint256 currBalance = ERC20(_token).balanceOf(address(this));

210: IPortStrategy(_strategy).withdraw(address(this), _token, amountToWithdraw);

214: ERC20(_token).balanceOf(address(this)) - currBalance == amountToWithdraw, "Port Strategy Withdraw Failed"

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L193

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L210

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L214

File: BranchPort.sol

436: uint256 currBalance = ERC20(_token).balanceOf(address(this));

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L436

File: BranchPort.sol

526: _localAddress.safeTransferFrom(_depositor, address(this), _hTokenAmount);

532: _underlyingAddress.safeTransferFrom(_depositor, address(this), _deposit);

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L526

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L532

File: BaseBranchRouter.sol

167: _hToken.safeTransferFrom(msg.sender, address(this), _amount - _deposit);

174: _token.safeTransferFrom(msg.sender, address(this), _deposit);

https://github.com/code-423n4/2023-09-maia/tree/main/src/BaseBranchRouter.sol#L167

https://github.com/code-423n4/2023-09-maia/tree/main/src/BaseBranchRouter.sol#L174

File: BranchBridgeAgentExecutor.sol

92: _recipient.safeTransferETH(address(this).balance);

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgentExecutor.sol#L92

File: BranchBridgeAgentExecutor.sol

126: _recipient.safeTransferETH(address(this).balance);

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgentExecutor.sol#L126

File: RootPort.sol

301: _hToken.safeTransferFrom(_from, address(this), _amount);

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L301

File: RootPort.sol

362: newAccount = new VirtualAccount{salt: keccak256(abi.encode(_user))}(_user, address(this));

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L362

File: RootBridgeAgent.sol

148: address(this),

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L148

File: RootBridgeAgent.sol

424: (bool success,) = address(this).excessivelySafeCall(

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L424

File: RootBridgeAgent.sol

695: address(this).balance

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L695

File: RootBridgeAgent.sol

779: (bool success,) = bridgeAgentExecutorAddress.call{value: address(this).balance}(_calldata);

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L779

File: RootBridgeAgent.sol

940: ILayerZeroEndpoint(lzEndpointAddress).send{value: address(this).balance}(

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L940

File: RootBridgeAgent.sol

1182: getBranchBridgeAgentPath[_branchChainId] = abi.encodePacked(_newBranchBridgeAgent, address(this));

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L1182

File: ArbitrumBranchPort.sol

66: _underlyingAddress.safeTransferFrom(_depositor, address(this), _deposit);

https://github.com/code-423n4/2023-09-maia/tree/main/src/ArbitrumBranchPort.sol#L66

File: ArbitrumBranchPort.sol

128: _underlyingAddress.safeTransferFrom(_depositor, address(this), _deposit);

https://github.com/code-423n4/2023-09-maia/tree/main/src/ArbitrumBranchPort.sol#L128

File: ERC20hTokenRootFactory.sol

83: address(this),

https://github.com/code-423n4/2023-09-maia/tree/main/src/factories/ERC20hTokenRootFactory.sol#L83

</details>

<a href="#gas-summary">[GAS‑7]</a><a name="GAS&#x2011;7"> Gas savings can be achieved by changing the model for assigning value to the structure

Here's an example to illustrate this:

    struct MyStruct {
        uint256 a;
        uint256 b;
        uint256 c;
    }

    function assignValuesToStruct(uint256 _a, uint256 _b, uint256 _c) public {
        MyStruct memory myStruct = MyStruct(_a, _b, _c);
        // Do something with myStruct
    }

In this example, we have a simple MyStruct data structure with three uint256 fields. The assignValuesToStruct function takes three input parameters _a, _b, and _c, and assigns them to the corresponding fields in a new myStruct variable. This is done using the struct constructor syntax, which creates a new instance of the MyStruct struct with the specified field values.

The following approach can be more efficient than assigning values to the struct fields:

    function assignValuesToStruct(uint256 _a, uint256 _b, uint256 _c) public {
        MyStruct memory myStruct;
        myStruct.a = _a;
        myStruct.b = _b;
        myStruct.c = _c;
        // Do something with myStruct
    }

By changing the pattern of assigning value to the structure, gas savings of ~130 per instance are achieved. In addition, this use will provide significant savings in distribution costs.

<ins>Proof Of Concept</ins>

<details>

File: RootBridgeAgentExecutor.sol

88: DepositParams memory dParams = DepositParams({
            depositNonce: uint32(bytes4(_payload[PARAMS_START:PARAMS_TKN_START])),
            hToken: address(uint160(bytes20(_payload[PARAMS_TKN_START:PARAMS_TKN_START_SIGNED]))),
            token: address(uint160(bytes20(_payload[PARAMS_TKN_START_SIGNED:45]))),
            amount: uint256(bytes32(_payload[45:77])),
            deposit: uint256(bytes32(_payload[77:PARAMS_TKN_SET_SIZE]))
        });

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgentExecutor.sol#L88

File: RootBridgeAgentExecutor.sol

173: DepositParams memory dParams = DepositParams({
            depositNonce: uint32(bytes4(_payload[PARAMS_START_SIGNED:PARAMS_TKN_START_SIGNED])),
            hToken: address(uint160(bytes20(_payload[PARAMS_TKN_START_SIGNED:45]))),
            token: address(uint160(bytes20(_payload[45:65]))),
            amount: uint256(bytes32(_payload[65:97])),
            deposit: uint256(bytes32(_payload[97:PARAMS_SETTLEMENT_OFFSET]))
        });

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgentExecutor.sol#L173

File: RootBridgeAgentExecutor.sol

338: dParams = DepositMultipleParams({
            numberOfAssets: numOfAssets,
            depositNonce: nonce,
            hTokens: hTokens,
            tokens: tokens,
            amounts: amounts,
            deposits: deposits
        });

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgentExecutor.sol#L338

File: BranchBridgeAgentExecutor.sol

72: SettlementParams memory sParams = SettlementParams({
            settlementNonce: uint32(bytes4(_payload[PARAMS_START_SIGNED:PARAMS_TKN_START_SIGNED])),
            recipient: _recipient,
            hToken: address(uint160(bytes20(_payload[PARAMS_TKN_START_SIGNED:45]))),
            token: address(uint160(bytes20(_payload[45:65]))),
            amount: uint256(bytes32(_payload[65:97])),
            deposit: uint256(bytes32(_payload[97:PARAMS_SETTLEMENT_OFFSET]))
        });

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgentExecutor.sol#L72

File: RootBridgeAgent.sol

402: DepositParams({
                    hToken: _dParams.hTokens[i],
                    token: _dParams.tokens[i],
                    amount: _dParams.amounts[i],
                    deposit: _dParams.deposits[i],
                    depositNonce: 0
                }),
                _srcChainId
            );

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L402

</details>

<a href="#gas-summary">[GAS‑8]</a><a name="GAS&#x2011;8"> Using unchecked blocks to save gas

Solidity version 0.8+ comes with implicit overflow and underflow checks on unsigned integers. When an overflow or an underflow isn’t possible (as an example, when a comparison is made before the arithmetic operation), some gas can be saved by using an unchecked block

<ins>Proof Of Concept</ins>

Optimize to the following in order to decrease a total of $\textcolor{green}{\textsf{-1159}}$ gas usage (includes proof of forge test runs):

unchecked {
    getPortStrategyTokenDebt[_strategy][_token] = portStrategyTokenDebt - amountToWithdraw;
}

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L205

unchecked {
    getStrategyTokenDebt[_token] = strategyTokenDebt - amountToWithdraw;
}

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L207

</details>

<ins>Forge test</ins>

Running forge test comparison report:

<details>

Ran 9 test suites: 140 tests passed, 0 failed, 0 skipped (140 total tests) testRetrieveSettlement() (gas: -5 (-0.000%))

testRetrySettlementTriggerFallback() (gas: -5 (-0.000%))

testRedeemSettlement() (gas: -5 (-0.000%))

testRetrySettlementNoFallback() (gas: -5 (-0.000%))

testRetrySettlement() (gas: -5 (-0.000%)) testRetryDeposit() (gas: -5 (-0.000%))

testRedeemDepositAfterRetrieve() (gas: -5 (-0.000%))

testRedeemDepositAfterFallback() (gas: -5 (-0.000%))

testAddBridgeAgentWrongBranchFactory() (gas: -5 (-0.000%)) testRetrySettlement() (gas: -5 (-0.000%)) testAddBridgeAgentWrongBranchFactory() (gas: -5 (-0.000%)) testAddLocalTokenNewCore() (gas: -25 (-0.000%))

testSyncNewCoreBranchRouter() (gas: -25 (-0.000%))

testSetCoreRootRouter() (gas: -25 (-0.000%))

testSetBranchRouter() (gas: -25 (-0.000%))

testRetryTwoSettlements() (gas: -10 (-0.000%))

testAddBridgeAgentTwoTimes() (gas: -20 (-0.000%))

testAddBridgeAgentNewFactory() (gas: -25 (-0.000%))

testAddBridgeAgentAlreadyAdded() (gas: -20 (-0.000%)) testAddBridgeAgentSimple() (gas: -20 (-0.000%))

testAddBridgeAgentWrongRootFactory() (gas: -20 (-0.000%)) testAddBridgeAgentTwice() (gas: -20 (-0.000%))

testAddBridgeAgentFactory() (gas: -10 (-0.000%))

testAddBridgeAgentAlreadyAdded() (gas: -20 (-0.000%)) testAddBridgeAgent() (gas: -20 (-0.000%))

testAddTwoBridgeAgentFactories() (gas: -25 (-0.000%))

testAddBridgeAgentWrongRootFactory() (gas: -20 (-0.000%)) testFuzzExecuteWithSettlement(address,uint256,uint256,uint16) (gas: -10 (-0.000%)) testRemoveBridgeAgentFactory() (gas: -30 (-0.000%))

testFuzzFallbackClearDepositRedeem(address,uint256,uint256,uint16) (gas: -10 (-0.001%)) testFallbackClearDepositRedeemDouble() (gas: -4 (-0.001%))

testFallbackClearDepositRedeemAlreadyRedeemed() (gas: -4 (-0.001%))

testFallbackClearDepositRedeemSuccess() (gas: -4 (-0.001%))

testAddStrategyToken() (gas: -15 (-0.001%))

testManageExceedsDailyLimit() (gas: -30 (-0.001%))

testManageExceedsMinimumReserves() (gas: -30 (-0.001%))

testAddPortStrategy() (gas: -30 (-0.001%))

testManage() (gas: -35 (-0.001%))

testAddBridgeAgentFactory() (gas: -10 (-0.001%))

testRemoveStrategyToken() (gas: -30 (-0.001%))

testManageTwoDayLimits() (gas: -40 (-0.001%))

testReplenishAsStrategyNotEnoughDebtToRepay() (gas: -40 (-0.001%))

testReplenishAsStrategy() (gas: -45 (-0.001%))

testAddPortStrategyNotToken() (gas: -15 (-0.002%))

testAddStrategyTokenInvalidMinReserve() (gas: -15 (-0.002%))

testRemoveBridgeAgent() (gas: -15 (-0.002%))

testRemoveBridgeAgentFactory() (gas: -30 (-0.003%))

testAddStrategyToken() (gas: -15 (-0.005%))

testAddPortStrategyNotToken() (gas: -15 (-0.006%))

testAddPortStrategy() (gas: -30 (-0.006%))

testReplenishAsUser() (gas: -212 (-0.007%))

testAddStrategyTokenInvalidMinReserve() (gas: -15 (-0.007%))

testRemoveBridgeAgent() (gas: -15 (-0.007%))

testRemoveStrategyToken() (gas: -30 (-0.008%))

Overall gas change: $\textcolor{green}{\textsf{-1159}}$ (-0.000%)

</details>

<a href="#gas-summary">[GAS‑9]</a><a name="GAS&#x2011;9"> require()/revert() Strings Longer Than 32 Bytes Cost Extra Gas

<ins>Proof Of Concept</ins>

Note: While the instances may be present in the automated findings, it is important to note that the automated findings also contain instances that will <b>increase</b> that gas cost. Hence, in order to provide actual valid instances, these are the only findings that will specifically <b>decrease</b> the gas usage

Optimize to the following in order to decrease a total of $\textcolor{green}{\textsf{-207456}}$ gas usage (includes proof of forge test runs):

<details><summary>Contains 8 gas optimization instances</summary>

require(_rootBridgeAgentAddress != address(0), "shortString");

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L125

require(_setup, "shortString");

https://github.com/code-423n4/2023-09-maia/tree/main/src/CoreRootRouter.sol#L84

require(_bridgeAgentAddress != address(0), "shortString");

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L110

require(ERC20(_token).balanceOf(address(this)) - currBalance == _amount, "shortString");

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L181

require(_localBridgeAgentAddress != address(0), "shortString");

https://github.com/code-423n4/2023-09-maia/tree/main/src/BaseBranchRouter.sol#L61

require(_coreRootBridgeAgent != address(0), "shortString");

https://github.com/code-423n4/2023-09-maia/tree/main/src/factories/BranchBridgeAgentFactory.sol#L88

require(_coreRouter != address(0), "shortString");

https://github.com/code-423n4/2023-09-maia/tree/main/src/factories/ERC20hTokenBranchFactory.sol#L61

require(_coreRouter != address(0), "shortString");

https://github.com/code-423n4/2023-09-maia/tree/main/src/factories/ERC20hTokenRootFactory.sol#L50

</details>

<ins>Forge test</ins>

Running forge test comparison report:

<details>

Ran 9 test suites: 140 tests passed, 0 failed, 0 skipped (140 total tests) testRetrieveSettlement() (gas: -5 (-0.000%))

testRetrySettlementTriggerFallback() (gas: -5 (-0.000%))

testRedeemSettlement() (gas: -5 (-0.000%))

testRetrySettlementNoFallback() (gas: -5 (-0.000%))

testRetrySettlement() (gas: -5 (-0.000%)) testRetryDeposit() (gas: -5 (-0.000%))

testRedeemDepositAfterRetrieve() (gas: -5 (-0.000%))

testRedeemDepositAfterFallback() (gas: -5 (-0.000%))

testRetrySettlement() (gas: -5 (-0.000%)) testRetryTwoSettlements() (gas: -10 (-0.000%))

testReplenishAsUser() (gas: 7 (0.000%))

testFuzzExecuteWithSettlement(address,uint256,uint256,uint16) (gas: -10 (-0.000%)) testFuzzFallbackClearDepositRedeem(address,uint256,uint256,uint16) (gas: -10 (-0.001%)) testFallbackClearDepositRedeemDouble() (gas: -4 (-0.001%))

testFallbackClearDepositRedeemAlreadyRedeemed() (gas: -4 (-0.001%))

testFallbackClearDepositRedeemSuccess() (gas: -4 (-0.001%))

testAddStrategyToken() (gas: -15 (-0.001%))

testManageExceedsDailyLimit() (gas: -30 (-0.001%))

testManageExceedsMinimumReserves() (gas: -30 (-0.001%))

testAddPortStrategy() (gas: -30 (-0.001%))

testManage() (gas: -35 (-0.001%))

testRemoveStrategyToken() (gas: -30 (-0.001%))

testManageTwoDayLimits() (gas: -40 (-0.001%))

testReplenishAsStrategyNotEnoughDebtToRepay() (gas: -40 (-0.001%))

testAddPortStrategyNotToken() (gas: -15 (-0.002%))

testAddStrategyTokenInvalidMinReserve() (gas: -15 (-0.002%))

testRemoveBridgeAgent() (gas: -15 (-0.002%))

testReplenishAsStrategy() (gas: -55 (-0.002%))

testAddStrategyToken() (gas: -15 (-0.005%))

testAddPortStrategyNotToken() (gas: -15 (-0.006%))

testAddPortStrategy() (gas: -30 (-0.006%))

testAddStrategyTokenInvalidMinReserve() (gas: -15 (-0.007%))

testRemoveBridgeAgent() (gas: -15 (-0.007%))

testRemoveStrategyToken() (gas: -30 (-0.008%))

testAddBridgeAgentWrongBranchFactory() (gas: -3414 (-0.046%))

testAddBridgeAgentAlreadyAdded() (gas: -6797 (-0.053%))

testAddBridgeAgentSimple() (gas: -6797 (-0.053%))

testAddBridgeAgentNewFactory() (gas: -9204 (-0.054%))

testAddBridgeAgentWrongBranchFactory() (gas: -3418 (-0.055%))

testAddBridgeAgentNotApproved() (gas: -3413 (-0.057%))

testAddBridgeAgentNotManager() (gas: -3413 (-0.057%))

testAddBridgeAgentNotApproved() (gas: -3413 (-0.058%))

testAddBridgeAgentNotManager() (gas: -3413 (-0.058%))

testAddBridgeAgentAlreadyAdded() (gas: -6801 (-0.062%))

testAddBridgeAgent() (gas: -6801 (-0.062%))

testAddBridgeAgentArbitrum() (gas: -6803 (-0.062%))

testAddBridgeAgentArbitrum() (gas: -6807 (-0.063%))

testAddLocalTokenNewCore() (gas: -14183 (-0.064%))

testAddBridgeAgentTwoTimes() (gas: -10214 (-0.072%))

testAddBridgeAgentWrongRootFactory() (gas: -9238 (-0.072%))

testSyncNewCoreBranchRouter() (gas: -14183 (-0.078%))

testSetCoreRootRouter() (gas: -14183 (-0.078%))

testSetBranchRouter() (gas: -14183 (-0.079%))

testAddBridgeAgentTwice() (gas: -10210 (-0.083%))

testRemoveBridgeAgentFactory() (gas: -5839 (-0.093%))

testAddBridgeAgentFactory() (gas: -5819 (-0.106%))

testAddTwoBridgeAgentFactories() (gas: -11643 (-0.107%))

testAddBridgeAgentFactoryNotRootFactory() (gas: -5809 (-0.129%))

testAddBridgeAgentWrongRootFactory() (gas: -9242 (-0.132%))

testRemoveBridgeAgentFactory() (gas: -5843 (-0.614%))

testAddBridgeAgentFactory() (gas: -5823 (-0.669%))

Overall gas change: $\textcolor{green}{\textsf{-207456}}$ (-0.029%)

</details>

<a href="#gas-summary">[GAS‑10]</a><a name="GAS&#x2011;10"> Counting down in for statements is more gas efficient

Counting down is more gas efficient than counting up because neither we are making zero variable to non-zero variable and also we will get gas refund in the last transaction when making non-zero to zero variable.

<ins>Proof Of Concept</ins>

<details>

File: BranchBridgeAgent.sol

447: for (uint256 i = 0; i < deposit.tokens.length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L447

File: BranchBridgeAgent.sol

513: for (uint256 i = 0; i < numOfAssets;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchBridgeAgent.sol#L513

File: RootBridgeAgentExecutor.sol

281: for (uint256 i = 0; i < uint256(uint8(numOfAssets));) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgentExecutor.sol#L281

File: VirtualAccount.sol

70: for (uint256 i = 0; i < length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/VirtualAccount.sol#L70

File: VirtualAccount.sol

90: for (uint256 i = 0; i < length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/VirtualAccount.sol#L90

File: MulticallRootRouter.sol

278: for (uint256 i = 0; i < outputParams.outputTokens.length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L278

File: MulticallRootRouter.sol

367: for (uint256 i = 0; i < outputParams.outputTokens.length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L367

File: MulticallRootRouter.sol

455: for (uint256 i = 0; i < outputParams.outputTokens.length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L455

File: MulticallRootRouter.sol

557: for (uint256 i = 0; i < outputTokens.length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/MulticallRootRouter.sol#L557

File: BranchPort.sol

257: for (uint256 i = 0; i < length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L257

File: BranchPort.sol

305: for (uint256 i = 0; i < length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/BranchPort.sol#L305

File: BaseBranchRouter.sol

192: for (uint256 i = 0; i < _hTokens.length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/BaseBranchRouter.sol#L192

File: RootBridgeAgent.sol

318: for (uint256 i = 0; i < settlement.hTokens.length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L318

File: RootBridgeAgent.sol

399: for (uint256 i = 0; i < length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L399

File: RootBridgeAgent.sol

1070: for (uint256 i = 0; i < hTokens.length;) {

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootBridgeAgent.sol#L1070

</details>

Test Code

contract GasTest is DSTest {
    Contract0 c0;
    Contract1 c1;
    function setUp() public {
        c0 = new Contract0();
        c1 = new Contract1();
    }
    function testGas() public {
        c0.AddNum();
        c1.AddNum();
    }
}

contract Contract0 {
    uint256 num = 3;
    function AddNum() public {
        uint256 _num = num;
        for(uint i=0;i<=9;i++){
            _num = _num +1;
        }
        num = _num;
    }
}

contract Contract1 {
    uint256 num = 3;
    function AddNum() public {
        uint256 _num = num;
        for(uint i=9;i>=0;i--){
            _num = _num +1;
        }
        num = _num;
    }
}

Gas Test Report

<a href="#gas-summary">[GAS‑11]</a><a name="GAS&#x2011;11"> Hash using assembly instead of solidity

Saves about ~80 gas

function solidityHash(uint256 a, uint256 b) public view {
    //unoptimized
    keccak256(abi.encodePacked(a, b));
}

Gas Test: 313

function assemblyHash(uint256 a, uint256 b) public view {
    //optimized
    assembly {
        mstore(0x00, a)
        mstore(0x20, b)
        let hashedVal := keccak256(0x00, 0x40)
    }
} 

Gas Test: 231

<ins>Proof Of Concept</ins>

File: RootPort.sol

362: newAccount = new VirtualAccount{salt: keccak256(abi.encode(_user))}(_user, address(this));

https://github.com/code-423n4/2023-09-maia/tree/main/src/RootPort.sol#L362