Inverse Finance contest - 0xRoxas's results

Gas Report

Optimizations found [5]

[G-01] Use nested if instead of && ⓘ

Breaking apart require and if statements saves gas.

Findings [2]:

/src/Oracle.sol Line(s): 97, 136

97:	if(twoDayLow > 0 && newBorrowingPower > twoDayLow) {
136:	if(twoDayLow > 0 && newBorrowingPower > twoDayLow) {

[G-02] Break Apart Require Statments Instead of && ⓘ

Breaking apart require and if statements saves gas.

Findings [7]:

/src/Market.sol Line(s): 75, 162, 173, 184, 195, 448, 512

75:	require(_liquidationIncentiveBps > 0 && _liquidationIncentiveBps < 10000, "Invalid liquidation incentive");
162:	require(_liquidationFactorBps > 0 && _liquidationFactorBps <= 10000, "Invalid liquidation factor");
173:	require(_replenishmentIncentiveBps > 0 && _replenishmentIncentiveBps < 10000, "Invalid replenishment incentive");
184:	require(_liquidationIncentiveBps > 0 && _liquidationIncentiveBps + liquidationFeeBps < 10000, "Invalid liquidation incentive");
195:	require(_liquidationFeeBps > 0 && _liquidationFeeBps + liquidationIncentiveBps < 10000, "Invalid liquidation fee");
448:	require(recoveredAddress != address(0) && recoveredAddress == from, "INVALID_SIGNER");
512:	require(recoveredAddress != address(0) && recoveredAddress == from, "INVALID_SIGNER");

[G-03] Unless Used for Variable Packing uint8 May Be More Expensive Than Using uint256 ⓘ

Same as bool's uint8 data causes uneeded overhead.

Findings [11]:

/src/Oracle.sol Line(s): 20, 85, 86, 87, 119, 120, 121

20:	uint8 tokenDecimals;
85:	uint8 feedDecimals = feeds[token].feed.decimals();
86:	uint8 tokenDecimals = feeds[token].tokenDecimals;
87:	uint8 decimals = 36 - feedDecimals - tokenDecimals;
119:	uint8 feedDecimals = feeds[token].feed.decimals();
120:	uint8 tokenDecimals = feeds[token].tokenDecimals;
121:	uint8 decimals = 36 - feedDecimals - tokenDecimals;

/src/Market.sol Line(s): 422, 486

422:	function borrowOnBehalf(address from, uint amount, uint deadline, uint8 v, bytes32 r, bytes32 s) public {
486:	function withdrawOnBehalf(address from, uint amount, uint deadline, uint8 v, bytes32 r, bytes32 s) public {

/src/DBR.sol Line(s): 13, 220

13:	uint8 public constant decimals = 18;
220:	uint8 v,

[G-04] immutable variables never initialized in the constructor can be made constant to save gas

dola is made immutable even though it is never set in the constructor and is always the same value. Consider changing dola to a constant data type to save gas.

Findings [1]:

src/market.sol Line(s): 44

44:	IERC20 public immutable dola = IERC20(0x865377367054516e17014CcdED1e7d814EDC9ce4);

Suggested change:

44:	IERC20 public constant dola = IERC20(0x865377367054516e17014CcdED1e7d814EDC9ce4);

[G-05] Using unchecked when arithmetic cannot overflow saves gas

There are mutliple occurances where arithmetic is performed that cannot overflow / underflow based on a previous require. Adding an unchecked brace around these occurances will save gas (Solidity will not force an underflow / overflow).

NOTE: Findings show the check before each line that allows the second line to be unchecked. Only the line following the check should be unchecked (NOT the check itself).

unchecked {
	//Code
}

Findings [7]:

src/Market.sol Line(s): 261-362, 378-379, 533-534

361:	if(collateralBalance <= minimumCollateral) return 0;
362:	return collateralBalance - minimumCollateral;

378:	if(collateralBalance <= minimumCollateral) return 0;
379:	return collateralBalance - minimumCollateral;

533:	require(debt >= amount, "Insufficient debt");
534:	debts[user] -= amount;

src/Fed.sol Line(s): 123-124

123:	if(supply >= marketValue) return 0;
124:	return marketValue - supply;

src/DBR.sol Line(s): 110-111, 123-124, 136-137

110:	if(totalDueTokensAccrued > _totalSupply) return 0;
111:	return _totalSupply - totalDueTokensAccrued;

123:	if(dueTokensAccrued[user] + accrued > balances[user]) return 0;
124:	return balances[user] - dueTokensAccrued[user] - accrued;

136:	if(dueTokensAccrued[user] + accrued < balances[user]) return 0;
137:	return dueTokensAccrued[user] + accrued - balances[user];