PartyDAO contest - ignacio's results

1) <ARRAY>.LENGTH SHOULD NOT BE LOOKED UP IN EVERY LOOP OF A FOR-LOOP and Increments can be unchecked

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) ++I COSTS LESS GAS THAN I++ 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 uint256 length = arr.length; For example for (uint i; i < length; ) { // do stuff unchecked { ++i; } }

https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/CollectionBuyCrowdfund.sol#L62 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/proposals/ArbitraryCallsProposal.sol#L52 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/proposals/ArbitraryCallsProposal.sol#L61 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/proposals/ArbitraryCallsProposal.sol#L78 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/distribution/TokenDistributor.sol#L230 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/distribution/TokenDistributor.sol#L239 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/proposals/ListOnOpenseaProposal.sol#L291 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/Crowdfund.sol#L180 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/Crowdfund.sol#L242 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/Crowdfund.sol#L348 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/party/PartyGovernance.sol#L306

2 USING CALLDATA INSTEAD OF MEMORY FOR READ-ONLY ARGUMENTS IN EXTERNAL FUNCTIONS SAVES GAS

When a function with a memory array is called externally, the abi.decode() step has to use a for-loop to copy each index of the calldata to the memory index. Each iteration of this for-loop costs at least 60 gas (i.e. 60 * <mem_array>.length). Using calldata directly, obliviates the need for such a loop in the contract code and runtime execution. If the array is passed to an internal function which passes the array to another internal function where the array is modified and therefore memory is used in the external call, it’s still more gass-efficient to use calldata when the external function uses modifiers, since the modifiers may prevent the internal functions from being called. Structs have the same overhead as an array of length one . If a reference type function parameter is read-only, it is cheaper in gas to use calldata instead of memory. Calldata is a non-modifiable, non-persistent area where function arguments are stored, and behaves mostly like memory. Try to use calldata as a data location because it will avoid copies and also makes sure that the data cannot be modified.

https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/proposals/ProposalExecutionEngine.sol#L116 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/AuctionCrowdfund.sol#L110 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/CrowdfundNFT.sol#L115 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/CrowdfundNFT.sol#L120 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/party/PartyGovernance.sol#L374 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/party/PartyGovernance.sol#L385 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/party/PartyGovernance.sol#L483

3 ABI.ENCODE() IS LESS EFFICIENT THAN ABI.ENCODEPACKED()

https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/proposals/ListOnZoraProposal.sol#L115 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/proposals/ListOnOpenseaProposal.sol#L164 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/proposals/ListOnOpenseaProposal.sol#L219

4 <X> += <Y> COSTS MORE GAS THAN <X> = <X> + <Y> FOR STATE VARIABLES

https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/Crowdfund.sol#L243 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/Crowdfund.sol#L352 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/Crowdfund.sol#L359 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/Crowdfund.sol#L374 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/Crowdfund.sol#L411 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/crowdfund/Crowdfund.sol#L427

5 MULTIPLE ADDRESS MAPPINGS CAN BE COMBINED INTO A SINGLE MAPPING OF AN ADDRESS TO A STRUCT, WHERE APPROPRIATE

Saves a storage slot for the mapping. Depending on the circumstances and sizes of types, can avoid a Gsset (20000 gas) per mapping combined. Reads and subsequent writes can also be cheaper when a function requires both values and they both fit in the same storage slot Saves a storage slot for the mapping. Depending on the circumstances and sizes of types, can avoid a Gsset (20000 gas) per mapping combined. Reads and subsequent writes can also be cheaper when a function requires both values and they both fit in the same storage slot. Finally, if both fields are accessed in the same function, can save ~42 gas per access due to not having to recalculate the key’s keccak256 hash (Gkeccak256 - 30 gas) and that calculation’s associated stack operations. https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/party/PartyGovernance.sol#L207 https://github.com/PartyDAO/party-contracts-c4/blob/main/contracts/distribution/TokenDistributor.sol#L64