The Graph L2 bridge contest - saian's results

Reduce size of revert stings

Revert strings that are longer than 32 bytes requires at least one additional mstore, along with additional overhead for computing memory offset, etc. Shortening revert strings to fit in 32 bytes will decrease deployment time gas and will decrease runtime gas when the revert condition is met.

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/upgrades/GraphUpgradeable.sol#L32

    require(msg.sender == _implementation(), "Caller must be the implementation"); 

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/governance/Managed.sol#L53

    require(msg.sender == controller.getGovernor(), "Caller must be Controller governor"); 

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/upgrades/GraphProxy.sol#L105

    require(_newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");

Use function arguments or local variables instead of storage variables in event emits

In event emits using local variables or function arguments instead of storage variable can avoid storage read and save gas

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/governance/Governed.sol#L46

    emit NewPendingOwnership(oldPendingGovernor, pendingGovernor); 

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/governance/Governed.sol#L65-L66

    emit NewOwnership(oldGovernor, governor); 
    emit NewPendingOwnership(oldPendingGovernor, pendingGovernor);

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/governance/Pausable.sol#L58

    emit NewPauseGuardian(oldPauseGuardian, pauseGuardian);

require statement can be split into multiple statements

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

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/governance/Governed.sol#L55

    require(
        pendingGovernor != address(0) && msg.sender == pendingGovernor,
        "Caller must be pending governor"
    );

Reduce storage reads to save gas

Storage values that are read multiple times in the same function can be cached to avoid expensive SLOAD and save gas

pendingGovernor can be replaced by variable oldPendingGovernor

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/governance/Governed.sol#L62

    address oldPendingGovernor = pendingGovernor;

    governor = pendingGovernor;

_partialPause can be replaced by _toPause

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/governance/Pausable.sol#L31

    _partialPaused = _toPause;
    if (_partialPaused)

_paused can be replaced by _toPause

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/governance/Pausable.sol#L44

    _paused = _toPause;
    if (_paused)

Switching from non-zero to non-zero is more efficient

By switching from non-zero to non-zero value, expensive SSTORE from 0/false to non-zero can be avoided. and when boolean is used, writing to storage costs more than uint256 as each write operation has to perform extra read operation to correctly place the boolean value in the slot. So switching from 0/false to 1/true can be replaced by 1 and 2

https://github.com/code-423n4/2022-10-thegraph/blob/309a188f7215fa42c745b136357702400f91b4ff/contracts/governance/Pausable.sol#L8-L10

    bool internal _partialPaused;
   
    bool internal _paused;