GAS

Constants expressions are expressions, not constants.

Summary

Constant expressions are left as expressions, not constants.

Details

Reference to this kind of issue: https://github.com/ethereum/solidity/issues/9232

Github Permalinks

https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/governance/governor/Governor.sol#L27 https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/lib/token/ERC721Votes.sol#L21 https://github.com/code-423n4/2022-09-nouns-builder/blob/c682e196982ca6953fe9fcb85df02748795394fd/src/lib/utils/EIP712.sol#L19

Mitigation

Use immutable for this expressions

Public function visibility can be made external

Summary

Functions should have the strictest visibility possible. Public functions may lead to more gas usage by forcing the copy of their parameters to memory from calldata.

Details

If a function is never called from the contract it should be marked as external. This will save gas.

Github Permalinks

Mitigation

Consider changing visibility from public to external.

usage of uints/ints smaller than 32 bytes (256 bits) incurs overhead

Summary

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.

Details

https://docs.soliditylang.org/en/v0.8.11/internals/layout_in_storage.html Use a larger size than downcast where needed

Github Permalinks

https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/lib/utils/Initializable.sol#L17 uint8 internal _initialized;

Mitigation

Consider using some data type that uses 32 bytes, for example uint256

Using bools for storage incurs overhead {

Summary

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.

Details

Here is one example of OpenZeppelin about this optimization https://github.com/OpenZeppelin/openzeppelin-contracts/blob/58f635312aa21f947cae5f8578638a85aa2519f5/contracts/security/ReentrancyGuard.sol#L23-L27 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

Github Permalinks

https://github.com/code-423n4/2022-09-nouns-builder/blob/c682e196982ca6953fe9fcb85df02748795394fd/src/lib/utils/Pausable.sol#L15 https://github.com/code-423n4/2022-09-nouns-builder/blob/c682e196982ca6953fe9fcb85df02748795394fd/src/lib/utils/Initializable.sol#L20

Mitigation

Consider using uint256 with values 0 and 1 rather than bool

Store using Struct over multiple mappings

Summary

All these variables could be combine in a Struct in order to reduce the gas cost.

Details

As noticed in: https://gist.github.com/alexon1234/b101e3ac51bea3cbd9cf06f80eaa5bc2 When multiple mappings that access the same addresses, uints, etc, all of them can be mixed into an struct and then that data accessed like: mapping(datatype => newStructCreated) newStructMap; Also, you have this post where it explains the benefits of using Structs over mappings https://medium.com/@novablitz/storing-structs-is-costing-you-gas-774da988895e

Github Permalinks

https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/governance/governor/storage/GovernorStorageV1.sol#L13-L19

https://github.com/code-423n4/2022-09-nouns-builder/blob/c682e196982ca6953fe9fcb85df02748795394fd/src/lib/token/ERC721.sol#L26 https://github.com/code-423n4/2022-09-nouns-builder/blob/c682e196982ca6953fe9fcb85df02748795394fd/src/lib/token/ERC721.sol#L34

https://github.com/code-423n4/2022-09-nouns-builder/blob/c682e196982ca6953fe9fcb85df02748795394fd/src/lib/token/ERC721.sol#L30 https://github.com/code-423n4/2022-09-nouns-builder/blob/c682e196982ca6953fe9fcb85df02748795394fd/src/lib/token/ERC721.sol#L38

https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/lib/token/ERC721Votes.sol#L29-L37

Mitigation

Consider mixing different mappings into a struct when able in order to save gas.

Using private rather than public for constants saves gas

Summary

If needed, the value can be read from the verified contract source code. Savings are due to the compiler not having to create non-payable getter functions for deployment calldata, and not adding another entry to the method ID table

Github Permalinks

https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/governance/governor/Governor.sol#L27 bytes32 public constant VOTE_TYPEHASH = keccak256("Vote(address voter,uint256 proposalId,uint256 support,uint256 nonce,uint256 deadline)");

Mitigation

Consider replacing public for private in constants for gas saving.

Index initialized in for loop

Summary

In for loops is not needed to initialize indexes to 0 as it is the default uint/int value. This saves gas.

Github Permalinks

https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/token/metadata/MetadataRenderer.sol#L119 for (uint256 i = 0; i < numNewProperties; ++i) {

https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/token/metadata/MetadataRenderer.sol#L133 for (uint256 i = 0; i < numNewItems; ++i) {

https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/token/metadata/MetadataRenderer.sol#L189 for (uint256 i = 0; i < numProperties; ++i) {

https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/token/metadata/MetadataRenderer.sol#L229 for (uint256 i = 0; i < numProperties; ++i) {

Mitigation

Don't initialize variables to default value

Variables should be cached when used several times

Summary

Variables read more than once improves gas usage when cached into local variable

Details

In loops or state variables, this is even more gas saving

Github Permalinks

newFounder https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/token/Token.sol#L113-L115

Mitigation

Cache variables used more than one into a local variable.

Shift right instead of dividing by 2

Summary

Shifting is cheaper than dividing by 2

Details

A division by 2 can be calculated by shifting one to the right. While the DIV opcode uses 5 gas, the SHR opcode only uses 3 gas. Furthermore, Solidity’s division operation also includes a division-by-0 prevention which is bypassed using shifting.

Github Permalinks

https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/lib/token/ERC721Votes.sol#L95 middle = high - (high - low) / 2;

Mitigation

Consider replacing / 2 with >> 1 here

Internal functions only called once can be inlined to save gas

Summary

Not inlining costs 20 to 40 gas because of two extra JUMP instructions and additional stack operations needed for function calls.

Github Permalinks

Mitigation

Consider changing internal function only called once to inline code for gas savings

abi.encode() is less gas efficient than abi.encodePacked()

Summary

In general, abi.encodePacked is more gas-efficient.

Details

Changing the abi.encode function to abi.encodePacked can save gas since the abi.encode function pads extra null bytes at the end of the call data, which is unnecessary. Also, in general, abi.encodePacked is more gas-efficient.

Github Permalinks

https://github.com/code-423n4/2022-09-nouns-builder/blob/c682e196982ca6953fe9fcb85df02748795394fd/src/lib/utils/EIP712.sol#L69 https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/governance/governor/Governor.sol#L104 https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/governance/governor/Governor.sol#L230 https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/governance/treasury/Treasury.sol#L107 https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/lib/token/ERC721Votes.sol#L162 https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/manager/Manager.sol#L68-L71 https://github.com/code-423n4/2022-09-nouns-builder/blob/debe9b792cc70510eadf9b3728cde5b0f2ec9a1f/src/token/metadata/MetadataRenderer.sol#L251

Mitigation

Consider changing abi.encode to abi.encodePacked

Functions guaranteed to revert when called by normal users can be marked payable

Summary

If a function modifier such as onlyOwner is used, the function will revert if a normal user tries to pay the function.

Marking the function as payable will lower the gas cost for legitimate callers because the compiler will not include checks for whether a payment was provided.

Details

The extra opcodes avoided are: CALLVALUE (2), DUP1 (3), ISZERO (3), PUSH2 (3), JUMPI (10), PUSH1 (3), DUP1 (3), REVERT(0), JUMPDEST (1), POP (2), which costs an average of about 21 gas per call to the function, in addition to the extra deployment cost