Gas Optimizations

[code423n4]

Gas Optimization

Serial No.	Issue Name	Instances
G-1	Using > 0 costs more gas than != 0 when used on a uint in a require() statement	3
G-2	Splitting require() statements that use && saves gas	1
G-3	Use custom errors rather than revert()/require() strings to save deployment gas	55
G-4	Usage of assert() instead of require()	3
G-5	Expressions for constant values such as a call to keccak256(), should use immutable rather than constant	2
G-6	abi.encode() is less efficient than abi.encodePacked()	6
G-7	Reduce the size of error messages (Long revert Strings)	4
G-8	Use calldata instead of memory in external functions	2
G-9	Using bools for storage incurs overhead	4
G-10	Usage of uints/ints smaller than 32 bytes (256 bits) incurs overhead	8
G-11	Use a more recent version of solidity	23
G-12	Use Assembly to check for address(0)	23
G-13	Inline a modifier that’s only used once	5

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Total instances found in this contest: 139 | Among all files in scope

1. Using > 0 costs more gas than != 0 when used on a uint in a require() statement

0 is less efficient than != 0 for unsigned integers (with proof) != 0 costs less gas compared to > 0 for unsigned integers in require statements with the optimizer enabled (6 gas) Proof: While it may seem that > 0 is cheaper than !=, this is only true without the optimizer enabled and outside a require statement. If you enable the optimizer at 10k AND you’re in a require statement, this will save gas. You can see this tweet for more proof: https://twitter.com/gzeon/status/1485428085885640706

Instances

L2GraphTokenGateway.sol:L146

contracts/l2/gateway/L2GraphTokenGateway.sol:146:        require(_amount > 0, "INVALID_ZERO_AMOUNT");

L1GraphTokenGateway.sol:L201

contracts/gateway/L1GraphTokenGateway.sol:201:        require(_amount > 0, "INVALID_ZERO_AMOUNT");

L1GraphTokenGateway.sol:L217

contracts/gateway/L1GraphTokenGateway.sol:217:                require(maxSubmissionCost > 0, "NO_SUBMISSION_COST");

Reference:

https://twitter.com/gzeon/status/1485428085885640706

Remediation:

I suggest changing > 0 with != 0. Also, please enable the Optimizer.

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2. Splitting require() statements that use && saves gas

Require statements including conditions with the && operator can be broken down in multiple require statements to save gas.

Instances

L1GraphTokenGateway.sol:L142

contracts/gateway/L1GraphTokenGateway.sol:142:        require(_escrow != address(0) && Address.isContract(_escrow), "INVALID_ESCROW");

Mitigation:

Breakdown each condition in a separate require statement (though require statements should be replaced with custom errors)

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3. Custom Errors instead of Revert Strings to save Gas

Custom errors from Solidity 0.8.4 are cheaper than revert strings (cheaper deployment cost and runtime cost when the revert condition is met). Starting from Solidity v0.8.4,there is a convenient and gas-efficient way to explain to users why an operation failed through the use of custom errors. Until now, you could already use strings to give more information about failures (e.g., revert("Insufficient funds.");),but they are rather expensive, especially when it comes to deploy cost, and it is difficult to use dynamic information in them. Custom errors are defined using the error statement, which can be used inside and outside of contracts (including interfaces and libraries).

Instances

L2GraphTokenGateway.sol:L98

contracts/l2/gateway/L2GraphTokenGateway.sol:98:        require(_l2Router != address(0), "INVALID_L2_ROUTER");

L2GraphTokenGateway.sol:L108

contracts/l2/gateway/L2GraphTokenGateway.sol:108:        require(_l1GRT != address(0), "INVALID_L1_GRT");

L2GraphTokenGateway.sol:L118

contracts/l2/gateway/L2GraphTokenGateway.sol:118:        require(_l1Counterpart != address(0), "INVALID_L1_COUNTERPART");

L2GraphTokenGateway.sol:L145

contracts/l2/gateway/L2GraphTokenGateway.sol:145:        require(_l1Token == l1GRT, "TOKEN_NOT_GRT");

L2GraphTokenGateway.sol:L146

contracts/l2/gateway/L2GraphTokenGateway.sol:146:        require(_amount > 0, "INVALID_ZERO_AMOUNT");

L2GraphTokenGateway.sol:L147

contracts/l2/gateway/L2GraphTokenGateway.sol:147:        require(msg.value == 0, "INVALID_NONZERO_VALUE");

L2GraphTokenGateway.sol:L148

contracts/l2/gateway/L2GraphTokenGateway.sol:148:        require(_to != address(0), "INVALID_DESTINATION");

L2GraphTokenGateway.sol:L153

contracts/l2/gateway/L2GraphTokenGateway.sol:153:        require(outboundCalldata.extraData.length == 0, "CALL_HOOK_DATA_NOT_ALLOWED");

L2GraphTokenGateway.sol:L233

contracts/l2/gateway/L2GraphTokenGateway.sol:233:        require(_l1Token == l1GRT, "TOKEN_NOT_GRT");

L2GraphTokenGateway.sol:L234

contracts/l2/gateway/L2GraphTokenGateway.sol:234:        require(msg.value == 0, "INVALID_NONZERO_VALUE");

L2GraphToken.sol:L36

contracts/l2/token/L2GraphToken.sol:36:        require(msg.sender == gateway, "NOT_GATEWAY");

L2GraphToken.sol:L49

contracts/l2/token/L2GraphToken.sol:49:        require(_owner != address(0), "Owner must be set");

L2GraphToken.sol:L60

contracts/l2/token/L2GraphToken.sol:60:        require(_gw != address(0), "INVALID_GATEWAY");

L2GraphToken.sol:L70

contracts/l2/token/L2GraphToken.sol:70:        require(_addr != address(0), "INVALID_L1_ADDRESS");

GraphTokenUpgradeable.sol:L60

contracts/l2/token/GraphTokenUpgradeable.sol:60:        require(isMinter(msg.sender), "Only minter can call");

GraphTokenUpgradeable.sol:L94

contracts/l2/token/GraphTokenUpgradeable.sol:94:        require(_owner == recoveredAddress, "GRT: invalid permit");

GraphTokenUpgradeable.sol:L95

contracts/l2/token/GraphTokenUpgradeable.sol:95:        require(_deadline == 0 || block.timestamp <= _deadline, "GRT: expired permit");

GraphTokenUpgradeable.sol:L106

contracts/l2/token/GraphTokenUpgradeable.sol:106:        require(_account != address(0), "INVALID_MINTER");

GraphTokenUpgradeable.sol:L115

contracts/l2/token/GraphTokenUpgradeable.sol:115:        require(_minters[_account], "NOT_A_MINTER");

GraphTokenUpgradeable.sol:L123

contracts/l2/token/GraphTokenUpgradeable.sol:123:        require(_minters[msg.sender], "NOT_A_MINTER");

GraphProxy.sol:L105

contracts/upgrades/GraphProxy.sol:105:        require(_newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");

GraphProxy.sol:L141

contracts/upgrades/GraphProxy.sol:141:        require(Address.isContract(_pendingImplementation), "Implementation must be a contract");

GraphProxy.sol:L157

contracts/upgrades/GraphProxy.sol:157:        require(msg.sender != _admin(), "Cannot fallback to proxy target");

GraphUpgradeable.sol:L24

contracts/upgrades/GraphUpgradeable.sol:24:        require(msg.sender == _proxy.admin(), "Caller must be the proxy admin");

GraphUpgradeable.sol:L32

contracts/upgrades/GraphUpgradeable.sol:32:        require(msg.sender == _implementation(), "Caller must be the implementation");

GraphProxyStorage.sol:L62

contracts/upgrades/GraphProxyStorage.sol:62:        require(msg.sender == _admin(), "Caller must be admin");

L1GraphTokenGateway.sol:L74

contracts/gateway/L1GraphTokenGateway.sol:74:        require(inbox != address(0), "INBOX_NOT_SET");

L1GraphTokenGateway.sol:L78

contracts/gateway/L1GraphTokenGateway.sol:78:        require(msg.sender == address(bridge), "NOT_FROM_BRIDGE");

L1GraphTokenGateway.sol:L82

contracts/gateway/L1GraphTokenGateway.sol:82:        require(l2ToL1Sender == l2Counterpart, "ONLY_COUNTERPART_GATEWAY");

L1GraphTokenGateway.sol:L110

contracts/gateway/L1GraphTokenGateway.sol:110:        require(_inbox != address(0), "INVALID_INBOX");

L1GraphTokenGateway.sol:L111

contracts/gateway/L1GraphTokenGateway.sol:111:        require(_l1Router != address(0), "INVALID_L1_ROUTER");

L1GraphTokenGateway.sol:L122

contracts/gateway/L1GraphTokenGateway.sol:122:        require(_l2GRT != address(0), "INVALID_L2_GRT");

L1GraphTokenGateway.sol:L132

contracts/gateway/L1GraphTokenGateway.sol:132:        require(_l2Counterpart != address(0), "INVALID_L2_COUNTERPART");

L1GraphTokenGateway.sol:L142

contracts/gateway/L1GraphTokenGateway.sol:142:        require(_escrow != address(0) && Address.isContract(_escrow), "INVALID_ESCROW");

L1GraphTokenGateway.sol:L153

contracts/gateway/L1GraphTokenGateway.sol:153:        require(_newWhitelisted != address(0), "INVALID_ADDRESS");

L1GraphTokenGateway.sol:L154

contracts/gateway/L1GraphTokenGateway.sol:154:        require(!callhookWhitelist[_newWhitelisted], "ALREADY_WHITELISTED");

L1GraphTokenGateway.sol:L165

contracts/gateway/L1GraphTokenGateway.sol:165:        require(_notWhitelisted != address(0), "INVALID_ADDRESS");

L1GraphTokenGateway.sol:L166

contracts/gateway/L1GraphTokenGateway.sol:166:        require(callhookWhitelist[_notWhitelisted], "NOT_WHITELISTED");

L1GraphTokenGateway.sol:L200

contracts/gateway/L1GraphTokenGateway.sol:200:        require(_l1Token == address(token), "TOKEN_NOT_GRT");

L1GraphTokenGateway.sol:L201

contracts/gateway/L1GraphTokenGateway.sol:201:        require(_amount > 0, "INVALID_ZERO_AMOUNT");

L1GraphTokenGateway.sol:L202

contracts/gateway/L1GraphTokenGateway.sol:202:        require(_to != address(0), "INVALID_DESTINATION");

L1GraphTokenGateway.sol:L217

contracts/gateway/L1GraphTokenGateway.sol:217:                require(maxSubmissionCost > 0, "NO_SUBMISSION_COST");

L1GraphTokenGateway.sol:L224

contracts/gateway/L1GraphTokenGateway.sol:224:                    require(msg.value >= expectedEth, "WRONG_ETH_VALUE");

L1GraphTokenGateway.sol:L271

contracts/gateway/L1GraphTokenGateway.sol:271:        require(_l1Token == address(token), "TOKEN_NOT_GRT");

L1GraphTokenGateway.sol:L275

contracts/gateway/L1GraphTokenGateway.sol:275:        require(_amount <= escrowBalance, "BRIDGE_OUT_OF_FUNDS");

GraphTokenGateway.sol:L31

contracts/gateway/GraphTokenGateway.sol:31:        require(_newPauseGuardian != address(0), "PauseGuardian must be set");

GraphTokenGateway.sol:L40

contracts/gateway/GraphTokenGateway.sol:40:        require(!_paused, "Paused (contract)");

Managed.sol:L44

contracts/governance/Managed.sol:44:        require(!controller.paused(), "Paused");

Managed.sol:L45

contracts/governance/Managed.sol:45:        require(!controller.partialPaused(), "Partial-paused");

Managed.sol:L49

contracts/governance/Managed.sol:49:        require(!controller.paused(), "Paused");

Managed.sol:L53

contracts/governance/Managed.sol:53:        require(msg.sender == controller.getGovernor(), "Caller must be Controller governor");

Managed.sol:L57

contracts/governance/Managed.sol:57:        require(msg.sender == address(controller), "Caller must be Controller");

Managed.sol:L104

contracts/governance/Managed.sol:104:        require(_controller != address(0), "Controller must be set");

Governed.sol:L24

contracts/governance/Governed.sol:24:        require(msg.sender == governor, "Only Governor can call");

Governed.sol:L41

contracts/governance/Governed.sol:41:        require(_newGovernor != address(0), "Governor must be set");

Remediation:

I suggest replacing revert strings with custom errors.

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4. Usage of assert() instead of require()

Between solc 0.4.10 and 0.8.0, require() used REVERT (0xfd) opcode which refunded the remaining gas on failure while assert() used INVALID (0xfe) opcode which consumed all the supplied gas. (see https://docs.soliditylang.org/en/v0.8.1/control-structures.html#error-handling-assert-require-revert-and-exceptions). 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.

Instances:

GraphProxy.sol:L47

contracts/upgrades/GraphProxy.sol:47:        assert(ADMIN_SLOT == bytes32(uint256(keccak256("eip1967.proxy.admin")) - 1));

GraphProxy.sol:L48

contracts/upgrades/GraphProxy.sol:48:        assert(

GraphProxy.sol:L51

contracts/upgrades/GraphProxy.sol:51:        assert(

References:

https://code4rena.com/reports/2022-05-bunker/#g-08-usage-of-assert-instead-of-require

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5. Expressions for constant values such as a call to keccak256(), should use immutable rather than constant

This results in the keccak operation being performed whenever the variable is used, increasing gas costs relative to just storing the output hash. Changing to immutable will only perform hashing on contract deployment which will save gas.

Instances:

GraphTokenUpgradeable.sol:L38

contracts/l2/token/GraphTokenUpgradeable.sol:38:    bytes32 private constant DOMAIN_NAME_HASH = keccak256("Graph Token");

GraphTokenUpgradeable.sol:L39

contracts/l2/token/GraphTokenUpgradeable.sol:39:    bytes32 private constant DOMAIN_VERSION_HASH = keccak256("0");

References:

https://github.com/code-423n4/2021-10-slingshot-findings/issues/3

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6. abi.encode() is less efficient than abi.encodepacked()

Use abi.encodepacked() instead of abi.encode()

Instances:

L2GraphTokenGateway.sol:L174

contracts/l2/gateway/L2GraphTokenGateway.sol:174:        return abi.encode(id);

L2GraphTokenGateway.sol:L275

contracts/l2/gateway/L2GraphTokenGateway.sol:275:                abi.encode(0, _data) // we don't need to track exitNums (b/c we have no fast exits) so we always use 0

GraphTokenUpgradeable.sol:L88

contracts/l2/token/GraphTokenUpgradeable.sol:88:                    abi.encode(PERMIT_TYPEHASH, _owner, _spender, _value, nonces[_owner], _deadline)

GraphTokenUpgradeable.sol:L162

contracts/l2/token/GraphTokenUpgradeable.sol:162:            abi.encode(

L1GraphTokenGateway.sol:L249

contracts/gateway/L1GraphTokenGateway.sol:249:        return abi.encode(seqNum);

L1GraphTokenGateway.sol:L342

contracts/gateway/L1GraphTokenGateway.sol:342:                abi.encode(emptyBytes, _data)

Reference:

https://code4rena.com/reports/2022-06-notional-coop#15-abiencode-is-less-efficient-than-abiencodepacked

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7. Reduce the size of error messages (Long revert Strings)

Shortening revert strings to fit in 32 bytes will decrease deployment time gas and will decrease runtime gas when the revert condition is met.

Revert strings that are longer than 32 bytes require at least one additional mstore, along with additional overhead for computing memory offset, etc.

Instances:

GraphProxy.sol:L105

contracts/upgrades/GraphProxy.sol:105:        require(_newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");

GraphProxy.sol:L141

contracts/upgrades/GraphProxy.sol:141:        require(Address.isContract(_pendingImplementation), "Implementation must be a contract");

GraphUpgradeable.sol:L32

contracts/upgrades/GraphUpgradeable.sol:32:        require(msg.sender == _implementation(), "Caller must be the implementation");

Managed.sol:L53

contracts/governance/Managed.sol:53:        require(msg.sender == controller.getGovernor(), "Caller must be Controller governor");

Recommendations:

I suggest shortening the revert strings to fit in 32 bytes, or using custom errors as described next.

Custom errors from Solidity 0.8.4 are cheaper than revert strings (cheaper deployment cost and runtime cost when the revert condition is met)

Source Custom Errors in Solidity:

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8. Use calldata instead of memory in external functions

Use calldata instead of memory in external functions to save gas.

Instances:

L2GraphTokenGateway.sol:L193

contracts/l2/gateway/L2GraphTokenGateway.sol:193:    ) external returns (bytes memory) {

L1GraphTokenGateway.sol:L198

contracts/gateway/L1GraphTokenGateway.sol:198:    ) external payable override notPaused returns (bytes memory) {

Reference:

https://code4rena.com/reports/2022-04-badger-citadel/#g-12-stakedcitadeldepositall-use-calldata-instead-of-memory

---

9. Using bools for storage incurs overhead

// Booleans are more expensive than uint256 or any type that takes up a full
// word because each write operation emits an extra SLOAD to first read the
// slot's contents, replace the bits taken up by the boolean, and then write
// back. This is the compiler's defense against contract upgrades and
// pointer aliasing, and it cannot be disabled.

Refer Here Use uint256(1) and uint256(2) for true/false to avoid a Gwarmaccess (100 gas) for the extra SLOAD, and to avoid Gsset (20000 gas) when changing from ‘false’ to ‘true’, after having been ‘true’ in the past

Instances:

GraphTokenUpgradeable.sol:L51

contracts/l2/token/GraphTokenUpgradeable.sol:51:    mapping(address => bool) private _minters;

L1GraphTokenGateway.sol:L35

contracts/gateway/L1GraphTokenGateway.sol:35:    mapping(address => bool) public callhookWhitelist;

Pausable.sol:L8

contracts/governance/Pausable.sol:8:    bool internal _partialPaused;

Pausable.sol:L10

contracts/governance/Pausable.sol:10:    bool internal _paused;

References:

https://code4rena.com/reports/2022-06-notional-coop#8-using-bools-for-storage-incurs-overhead

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10. 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

Instances:

IStaking.sol:L47

contracts/staking/IStaking.sol:47:        uint32 _indexingRewardCut,

IStaking.sol:L48

contracts/staking/IStaking.sol:48:        uint32 _queryFeeCut,

IStaking.sol:L49

contracts/staking/IStaking.sol:49:        uint32 _cooldownBlocks

IStakingData.sol:L37

contracts/staking/IStakingData.sol:37:        uint32 cooldownBlocks; // Blocks to wait before updating parameters

IStakingData.sol:L38

contracts/staking/IStakingData.sol:38:        uint32 indexingRewardCut; // in PPM

IStakingData.sol:L39

contracts/staking/IStakingData.sol:39:        uint32 queryFeeCut; // in PPM

GraphTokenUpgradeable.sol:L79

contracts/l2/token/GraphTokenUpgradeable.sol:79:        uint8 _v,

IGraphToken.sol:L33

contracts/token/IGraphToken.sol:33:        uint8 _v,

References:

https://code4rena.com/reports/2022-04-phuture#g-14-usage-of-uintsints-smaller-than-32-bytes-256-bits-incurs-overhead

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11. Use a more recent version of solidity

Use a solidity version of at least 0.8.2 to get simple compiler automatic inlining Use a solidity version of at least 0.8.3 to get better struct packing and cheaper multiple storage reads Use a solidity version of at least 0.8.4 to get custom errors, which are cheaper at deployment than revert()/require() strings Use a solidity version of at least 0.8.10 to have external calls skip contract existence checks if the external call has a return value

Instances:

ICuration.sol:L3

contracts/curation/ICuration.sol:3:pragma solidity ^0.7.6;

IGraphCurationToken.sol:L3

contracts/curation/IGraphCurationToken.sol:3:pragma solidity ^0.7.6;

IStaking.sol:L3

contracts/staking/IStaking.sol:3:pragma solidity >=0.6.12 <0.8.0;

IStakingData.sol:L3

contracts/staking/IStakingData.sol:3:pragma solidity >=0.6.12 <0.8.0;

L2GraphTokenGateway.sol:L3

contracts/l2/gateway/L2GraphTokenGateway.sol:3:pragma solidity ^0.7.6;

L2GraphToken.sol:L3

contracts/l2/token/L2GraphToken.sol:3:pragma solidity ^0.7.6;

GraphTokenUpgradeable.sol:L3

contracts/l2/token/GraphTokenUpgradeable.sol:3:pragma solidity ^0.7.6;

IGraphProxy.sol:L3

contracts/upgrades/IGraphProxy.sol:3:pragma solidity ^0.7.6;

GraphProxyAdmin.sol:L3

contracts/upgrades/GraphProxyAdmin.sol:3:pragma solidity ^0.7.6;

GraphProxy.sol:L3

contracts/upgrades/GraphProxy.sol:3:pragma solidity ^0.7.6;

GraphUpgradeable.sol:L3

contracts/upgrades/GraphUpgradeable.sol:3:pragma solidity ^0.7.6;

GraphProxyStorage.sol:L3

contracts/upgrades/GraphProxyStorage.sol:3:pragma solidity ^0.7.6;

L1GraphTokenGateway.sol:L3

contracts/gateway/L1GraphTokenGateway.sol:3:pragma solidity ^0.7.6;

ICallhookReceiver.sol:L9

contracts/gateway/ICallhookReceiver.sol:9:pragma solidity ^0.7.6;

BridgeEscrow.sol:L3

contracts/gateway/BridgeEscrow.sol:3:pragma solidity ^0.7.6;

GraphTokenGateway.sol:L3

contracts/gateway/GraphTokenGateway.sol:3:pragma solidity ^0.7.6;

IEpochManager.sol:L3

contracts/epochs/IEpochManager.sol:3:pragma solidity ^0.7.6;

IRewardsManager.sol:L3

contracts/rewards/IRewardsManager.sol:3:pragma solidity ^0.7.6;

Pausable.sol:L3

contracts/governance/Pausable.sol:3:pragma solidity ^0.7.6;

Managed.sol:L3

contracts/governance/Managed.sol:3:pragma solidity ^0.7.6;

Governed.sol:L3

contracts/governance/Governed.sol:3:pragma solidity ^0.7.6;

IController.sol:L3

contracts/governance/IController.sol:3:pragma solidity >=0.6.12 <0.8.0;

IGraphToken.sol:L3

contracts/token/IGraphToken.sol:3:pragma solidity ^0.7.6;

References:

https://code4rena.com/reports/2022-06-notional-coop/#10-use-a-more-recent-version-of-solidity

---

12. Use assembly to check for address(0)

Saves 6 gas per instance if using assembly to check for address(0)

e.g.

assembly {
 if iszero(_addr) {
  mstore(0x00, 'zero address')
  revert(0x00, 0x20)
 }
}

Instances

L2GraphTokenGateway.sol:L98

contracts/l2/gateway/L2GraphTokenGateway.sol:98:        require(_l2Router != address(0), "INVALID_L2_ROUTER");

L2GraphTokenGateway.sol:L108

contracts/l2/gateway/L2GraphTokenGateway.sol:108:        require(_l1GRT != address(0), "INVALID_L1_GRT");

L2GraphTokenGateway.sol:L118

contracts/l2/gateway/L2GraphTokenGateway.sol:118:        require(_l1Counterpart != address(0), "INVALID_L1_COUNTERPART");

L2GraphTokenGateway.sol:L148

contracts/l2/gateway/L2GraphTokenGateway.sol:148:        require(_to != address(0), "INVALID_DESTINATION");

L2GraphToken.sol:L49

contracts/l2/token/L2GraphToken.sol:49:        require(_owner != address(0), "Owner must be set");

L2GraphToken.sol:L60

contracts/l2/token/L2GraphToken.sol:60:        require(_gw != address(0), "INVALID_GATEWAY");

L2GraphToken.sol:L70

contracts/l2/token/L2GraphToken.sol:70:        require(_addr != address(0), "INVALID_L1_ADDRESS");

GraphTokenUpgradeable.sol:L106

contracts/l2/token/GraphTokenUpgradeable.sol:106:        require(_account != address(0), "INVALID_MINTER");

GraphProxy.sol:L105

contracts/upgrades/GraphProxy.sol:105:        require(_newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");

GraphProxy.sol:L143

contracts/upgrades/GraphProxy.sol:143:            _pendingImplementation != address(0) && msg.sender == _pendingImplementation,

L1GraphTokenGateway.sol:L74

contracts/gateway/L1GraphTokenGateway.sol:74:        require(inbox != address(0), "INBOX_NOT_SET");

L1GraphTokenGateway.sol:L110

contracts/gateway/L1GraphTokenGateway.sol:110:        require(_inbox != address(0), "INVALID_INBOX");

L1GraphTokenGateway.sol:L111

contracts/gateway/L1GraphTokenGateway.sol:111:        require(_l1Router != address(0), "INVALID_L1_ROUTER");

L1GraphTokenGateway.sol:L122

contracts/gateway/L1GraphTokenGateway.sol:122:        require(_l2GRT != address(0), "INVALID_L2_GRT");

L1GraphTokenGateway.sol:L132

contracts/gateway/L1GraphTokenGateway.sol:132:        require(_l2Counterpart != address(0), "INVALID_L2_COUNTERPART");

L1GraphTokenGateway.sol:L142

contracts/gateway/L1GraphTokenGateway.sol:142:        require(_escrow != address(0) && Address.isContract(_escrow), "INVALID_ESCROW");

L1GraphTokenGateway.sol:L153

contracts/gateway/L1GraphTokenGateway.sol:153:        require(_newWhitelisted != address(0), "INVALID_ADDRESS");

L1GraphTokenGateway.sol:L165

contracts/gateway/L1GraphTokenGateway.sol:165:        require(_notWhitelisted != address(0), "INVALID_ADDRESS");

L1GraphTokenGateway.sol:L202

contracts/gateway/L1GraphTokenGateway.sol:202:        require(_to != address(0), "INVALID_DESTINATION");

GraphTokenGateway.sol:L31

contracts/gateway/GraphTokenGateway.sol:31:        require(_newPauseGuardian != address(0), "PauseGuardian must be set");

Managed.sol:L104

contracts/governance/Managed.sol:104:        require(_controller != address(0), "Controller must be set");

Governed.sol:L41

contracts/governance/Governed.sol:41:        require(_newGovernor != address(0), "Governor must be set");

Governed.sol:L55

contracts/governance/Governed.sol:55:            pendingGovernor != address(0) && msg.sender == pendingGovernor,

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13. Inline a modifier that’s only used once

Description

As notDelegated() is only used once in this contract (in function proxiableUUID()), it should get inlined to save gas:

Instances 1

GraphTokenUpgradeable.sol:L59

contracts/l2/token/GraphTokenUpgradeable.sol:59:    modifier onlyMinter() {

Instances where modifiers is used only once

GraphTokenUpgradeable.sol:L132

contracts/l2/token/GraphTokenUpgradeable.sol:132:    function mint(address _to, uint256 _amount) external onlyMinter {

Instances 2

L2GraphTokenGateway.sol:L68

contracts/l2/gateway/L2GraphTokenGateway.sol:68:    modifier onlyL1Counterpart() {

Instances where modifiers is used only once

L2GraphTokenGateway.sol:L232

contracts/l2/gateway/L2GraphTokenGateway.sol:232:    ) external payable override notPaused onlyL1Counterpart nonReentrant {

Instances 3

Managed.sol:L71

contracts/governance/Managed.sol:71:    modifier onlyController() {

Instances where modifiers is used only once

Managed.sol:L95

contracts/governance/Managed.sol:95:    function setController(address _controller) external onlyController {

Instances 4

L1GraphTokenGateway.sol:L73

contracts/gateway/L1GraphTokenGateway.sol:73:    modifier onlyL2Counterpart() {

Instances where modifiers is used only once

L1GraphTokenGateway.sol:L269

contracts/gateway/L1GraphTokenGateway.sol:269:    ) external payable override notPaused onlyL2Counterpart {

Instances 5

GraphTokenGateway.sol:L18

contracts/gateway/GraphTokenGateway.sol:18:    modifier onlyGovernorOrGuardian() {

Instances where modifiers is used only once

GraphTokenGateway.sol:L47

contracts/gateway/GraphTokenGateway.sol:47:    function setPaused(bool _newPaused) external onlyGovernorOrGuardian {

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