Yieldy contest - Fabble's results

Gas:

In LiquidityReserve.sol

• in unstakeAllRewardTokens you can save stakingContract as a local variable to save a (warm) SLOAD.
• in removeLiquidity you can avoid the require(_amount <= balanceOf(msg.sender), "Not enough lr tokens") as that check is already performed during _burn(msg.sender, _amount)
• in _calculateReserveTokenValue you can declare a named returns variable as returns (uint256 convertedAmount) to save some gas for declaring another variable.
• in enableLiquidityReserve you can save stakingToken as a local variable to save a storage read.

In BatchRequests.sol

• in canBatchContracts you can add a local variable address currContract outside the for loop and in the loop do currContract = contracts[i] to save a (warm) SLOAD. Here you can also use a named returns statement like returns (Batch[] memory batch) to avoid declaring the local batch variable and save gas.
• in sendWithdrawalRequests you can do the same for the currContract = contracts[i]

In Yieldy.sol

• in initialize you can rewrite the linked code to this

    decimal = _decimal;
    uint256 oneToken = 10**_decimal;
    WAD = oneToken;
    rebasingCreditsPerToken = oneToken;
    _setIndex(oneToken);

to save potentially 3 SLOADs

• here in rebase you can use directly currentTotalSupply instead of _totalSupply
• in _storeRebase you can save _totalSupply in a local var as it's read 2 times from storage
• in _burn here you can use currentCredits directly instead of reading creditBalances[_address] from storage again

In Staking.sol:

• In initialize you can always use function arguments instead of reading from the storage eg instead of if (CURVE_POOL != address(0)) { you should do if (_curvePool != address(0)) { so to save some gas
• In _sendAffiliateFee you can read both affiliateFee and FEE_ADDRESS into local vars to save 2 SLOAD in total
• In transferToke you can read FEE_ADDRESS into local var to save some gas
• In _isClaimAvailable you can change info from memory to storage to avoid creating a copy in memory and read alwyas directly from storage
• In _isClaimWithdrawAvailable you can change memory to storage for info like said before. Here you can also create a local variable for withdrawalAmount to avoid reading it twice.
• In _requestWithdrawalFromTokemak you can also create a local variable for TOKE_POOL to avoid reading it twice.
• In sendWithdrawalRequests you can read requestWithdrawalAmount into a local var. Same in
  • claim for YIELDY_TOKEN
  • claimWithdraw for YIELDY_TOKEN
  • _retrieveBalanceFromUser for YIELDY_TOKEN
  • instantUnstakeReserve for LIQUIDITY_RESERVE
  • instantUnstakeCurve for CURVE_POOL, curvePoolFrom and curvePoolTo
• In stake you can read YIELDY_TOKEN into a local var to save potentially up to 3 SLOADs. Similarly also for warmUpPeriod.

General

• in structs like Rebase, Claim and Epoch some values can be safely reduced in precision, so to pack values into 32 bytes. eg instead of this

struct Epoch {
    uint256 duration; // length of the epoch (in seconds)
    uint256 number; // epoch number (starting 1)
    uint256 timestamp; // epoch start time
    uint256 endTime; // time that current epoch ends on
    uint256 distribute; // amount of rewards to distribute this epoch
}

you can do this

struct Epoch {
    uint32 duration; // length of the epoch (in seconds)
    uint32 number; // epoch number (starting 1)
    uint32 timestamp; // epoch start time
    uint32 endTime; // time that current epoch ends on
    uint128 distribute; // amount of rewards to distribute this epoch
}

in this way you can use a single storage slot instead of 5 slots which is a pretty significant saving both for reads and writes.

• by using solidity errors instead of strings you can reduce the bytecode size which in turns will allows you to increase the compiler runs which will reduce the overall gas cost of executing most of the methods. Eg in Staking.sol you can replace instances like this (one)[https://github.com/code-423n4/2022-06-yieldy/blob/main/src/contracts/Staking.sol#L118]

require(_recipient.amount > 0, "Must enter valid amount");

to

error InvalidAmount();

if (_recipient.amount == 0)
    revert InvalidAmount();

same for all errors.