Gas Optimizations

[code423n4]

Gas report

G-N	Issue
[G‑01]	Use function parameter to avoid MLOAD
[G‑02]	Unused SafeMath.sol
[G‑03]	Use function saved var instead of SLOAD and address(0)
[G‑04]	Overcheck slots
[G‑05]	Getters with ownership modifier and marked as external
[G‑06]	Overcheck _pendingImplementation and pendingGovernor

[G-01] Use function parameter to avoid MLOAD

File: /contracts/governance/Governed.sol

45        emit NewPendingOwnership(oldPendingGovernor, pendingGovernor);

File: /contracts/governance/Pausable.sol

31        if (_partialPaused) {

34        emit PartialPauseChanged(_partialPaused);

44        _paused = _toPause;

48        emit PauseChanged(_paused);

58        emit NewPauseGuardian(oldPauseGuardian, pauseGuardian);

File: /contracts/l2/token/L2GraphToken.sol

62        emit GatewaySet(gateway);

[G-02] Unused SafeMath.sol

File: /contracts/l2/token/L2GraphToken.sol

 5 import "@openzeppelin/contracts/math/SafeMath.sol";

16    using SafeMath for uint256;

File: /contracts/l2/gateway/L2GraphTokenGateway.sol

 7 import "@openzeppelin/contracts/math/SafeMath.sol";

24    using SafeMath for uint256;

File: /contracts/l2/token/GraphTokenUpgradeable.sol

 7 import "@openzeppelin/contracts/math/SafeMath.sol";

29    using SafeMath for uint256;

From:
97        nonces[_owner] = nonces[_owner].add(1);
To:
97        ++nonces[_owner];

[G-03] Use function saved var instead of SLOAD and address(0)

File: /contracts/governance/Governed.sol#L53-L67

     function acceptOwnership() external {
+        address oldPendingGovernor = pendingGovernor;
         require(
-            pendingGovernor != address(0) && msg.sender == pendingGovernor,
+            oldPendingGovernor != address(0) && msg.sender == oldPendingGovernor,
             "Caller must be pending governor"
         );

         address oldGovernor = governor;
-        address oldPendingGovernor = pendingGovernor;

-        governor = pendingGovernor;
+        governor = oldPendingGovernor;
         pendingGovernor = address(0);

-        emit NewOwnership(oldGovernor, governor);
-        emit NewPendingOwnership(oldPendingGovernor, pendingGovernor);
+        emit NewOwnership(oldGovernor, oldPendingGovernor);
+        emit NewPendingOwnership(oldPendingGovernor, address(0));
     }
 }

[G-04] Overcheck slots

Can check this slots in a test or you can calculate directly in the slot definition

File: /contracts/upgrades/GraphProxy.sol

47        assert(ADMIN_SLOT == bytes32(uint256(keccak256("eip1967.proxy.admin")) - 1));

48        assert(
49            IMPLEMENTATION_SLOT == bytes32(uint256(keccak256("eip1967.proxy.implementation")) - 1)
50        );

51        assert(
52            PENDING_IMPLEMENTATION_SLOT ==
53                bytes32(uint256(keccak256("eip1967.proxy.pendingImplementation")) - 1)
54        );

[G-05] Getters with ownership modifier and marked as external

These functions could be marked as view functions and the ifAdminOrPendingImpl modifier removed

File: /contracts/upgrades/GraphProxy.sol

69    function admin() external ifAdminOrPendingImpl returns (address) {

82    function implementation() external ifAdminOrPendingImpl returns (address) {

95    function pendingImplementation() external ifAdminOrPendingImpl returns (address) {

[G-06] Overcheck _pendingImplementation and pendingGovernor

If the msg.sender it's the _pendingImplementation => the _pendingImplementation it's not the address(0) The msg.sender == _pendingImplementation check it's enough

File: /contracts/upgrades/GraphProxy.sol

143            _pendingImplementation != address(0) && msg.sender == _pendingImplementation,

The same case to pendingGovernor

File: /governance/Governed.sol

55            pendingGovernor != address(0) && msg.sender == pendingGovernor,