Yield Witch v2 contest - MadWookie's results

Gas Report

1. Order require() statements from least expensive to most expensive.

This lowers average gas used on instances of reverts.

Move this statement to the beginning of cancel(), saving around 2000 gas on average.

require(cauldron.level(vaultId) >= 0, "Undercollateralized");

File:Witch.sol#L256

2. Boolean storage variables are more expensive than uint256

Consider changing these to uint256 and perform casting to bool when necessary.

mapping(address => bool) public otherWitches;

File:Witch.sol#L68

mapping(bytes6 => mapping(bytes6 => bool)) public ignoredPairs;

File:Witch.sol#L69

3. Caching a struct to memory and only using once is more expensive than directly reading from storage

In this case I'm not sure the technical reason for why this is cheaper since _calcAuction() needs a memory struct so it must be converted anyways.

In my testing I found not caching debt before _calcAuction() function call saves 42 gas on average.

DataTypes.Debt memory debt = cauldron.debt(series.baseId, vault.ilkId);

File:Witch.sol#L192

4. +=-= costs more gas than = +\ = -.

saves 25 gas on average

limits_.sum += auction_.ink;

File:Witch.sol#L204

next two save 4 gas on average

limits_.sum -= auction_.ink;

File:Witch.sol#L430

auction_.art -= artIn.u128();

File:Witch.sol#L450

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

This saves gas by removing the msg.value > 0 check.

This appears to be pretty common at this point so I don't believe it degrades readability.

point()

File:Witch.sol#L83

setLine()

File:Witch.sol#L95

setLimit()

File:Witch.sol#L126

setAnotherWitch()

File:Witch.sol#L141

setIgnoredPair()

File:Witch.sol#L150

setAuctioneerReward()

File:Witch.sol#L161