Gas Optimizations

[code423n4]

Gas Optimizations

Gas savings are estimated using the gas report of existing forge test --gas-report tests (the sum of all deployment costs and the sum of the costs of calling methods) and may vary depending on the implementation of the fix.

	Issue	Instances	Estimated gas(deployments)	Estimated gas(min method call)	Estimated gas(avg method call)	Estimated gas(max method call)
1	State variables only set in the constructor should be declared immutable	2	117 275	104	110	110
2	Use function instead of modifiers	4	115 926	162	-264	-481
3	Duplicated require()/revert() checks should be refactored to a modifier or function	11	114 932	-59	-284	-398
4	Multiple address mappings can be combined into a single mapping of an address to a struct, where appropriate	5	24 227	254	533	-6 726
5	Expression can be unchecked when overflow is not possible	6	20 220	410	4 630	1354
6	State variables can be packed into fewer storage slots	1	-5 008	1 911	15 525	20 972
7	refactoring similar statements	1	18 422	-18	-11	6
8	Better algorithm for underflow check	3	12 613	656	8 332	3 741
9	x = x + y is cheaper than x += y	12	11 214	180	468	616
10	internal functions only called once can be inlined to save gas	1	5 207	67	47	24
11	State variables should be cached in stack variables rather than re-reading them from storage	2	5 007	478	1 117	1 423
	Overall gas savings	48	416 802 (6,58%)	3 423 (0,34%)	15 773 (0,82%)	18 283 (0,72%)

Total: 48 instances over 11 issues

---

1. State variables only set in the constructor should be declared immutable (2 instances)

Deployment. Gas Saved: 117 275

Minimum Method Call. Gas Saved: 104

Average Method Call. Gas Saved: 110

Maximum Method Call. Gas Saved: 110

Overall gas change: -678 (-0.723%)

Avoids a Gsset (20000 gas) in the constructor, and replaces each Gwarmacces (100 gas) with a PUSH32 (3 gas).

- src/DBR.sol:11, 12

NOTE: name and symbol must be within 32 bytes

diff --git a/src/DBR.sol b/src/DBR.sol
index aab6daf..013960f 100644
--- a/src/DBR.sol
+++ b/src/DBR.sol
@@ -8,8 +8,8 @@ pragma solidity ^0.8.13;
    8,   8: */
    9,   9: contract DolaBorrowingRights {
   10,  10: 
-  11     :-    string public name;
-  12     :-    string public symbol;
+       11:+    bytes32 public immutable name;
+       12:+    bytes32 public immutable symbol;
   13,  13:     uint8 public constant decimals = 18;
   14,  14:     uint256 public _totalSupply;
   15,  15:     address public operator;
@@ -34,8 +34,8 @@ contract DolaBorrowingRights {
   34,  34:         address _operator
   35,  35:     ) {
   36,  36:         replenishmentPriceBps = _replenishmentPriceBps;
-  37     :-        name = _name;
-  38     :-        symbol = _symbol;
+       37:+        name = bytes32(bytes(_name));
+       38:+        symbol = bytes32(bytes(_symbol));
   39,  39:         operator = _operator;
   40,  40:         INITIAL_CHAIN_ID = block.chainid;
   41,  41:         INITIAL_DOMAIN_SEPARATOR = computeDomainSeparator();
@@ -268,7 +268,7 @@ contract DolaBorrowingRights {
  268, 268:             keccak256(
  269, 269:                 abi.encode(
  270, 270:                     keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
- 271     :-                    keccak256(bytes(name)),
+      271:+                    keccak256(bytes.concat(name)),
  272, 272:                     keccak256("1"),
  273, 273:                     block.chainid,
  274, 274:                     address(this)

---

2. Use function instead of modifiers (4 instances)

Deployment. Gas Saved: 115 926

Minimum Method Call. Gas Saved: 162

Average Method Call. Gas Saved: -264

Maximum Method Call. Gas Saved: -481

Overall gas change: 734 (2.459%)

- src/BorrowController.sol:17

diff --git a/src/BorrowController.sol b/src/BorrowController.sol
index 6decad1..080a4e3 100644
--- a/src/BorrowController.sol
+++ b/src/BorrowController.sol
@@ -14,28 +14,36 @@ contract BorrowController {
   14,  14:         operator = _operator;
   15,  15:     }
   16,  16: 
-  17     :-    modifier onlyOperator {
+       17:+    function onlyOperator() private view {
   18,  18:         require(msg.sender == operator, "Only operator");
-  19     :-        _;
   20,  19:     }
   21,  20:     
   22,  21:     /**
   23,  22:     @notice Sets the operator of the borrow controller. Only callable by the operator.
   24,  23:     @param _operator The address of the new operator.
   25,  24:     */
-  26     :-    function setOperator(address _operator) public onlyOperator { operator = _operator; }
+       25:+    function setOperator(address _operator) public { 
+       26:+        onlyOperator();
+       27:+        operator = _operator; 
+       28:+    }
   27,  29: 
   28,  30:     /**
   29,  31:     @notice Allows a contract to use the associated market.
   30,  32:     @param allowedContract The address of the allowed contract
   31,  33:     */
-  32     :-    function allow(address allowedContract) public onlyOperator { contractAllowlist[allowedContract] = true; }
+       34:+    function allow(address allowedContract) public { 
+       35:+        onlyOperator();
+       36:+        contractAllowlist[allowedContract] = true; 
+       37:+    }
   33,  38: 
   34,  39:     /**
   35,  40:     @notice Denies a contract to use the associated market
   36,  41:     @param deniedContract The addres of the denied contract
   37,  42:     */
-  38     :-    function deny(address deniedContract) public onlyOperator { contractAllowlist[deniedContract] = false; }
+       43:+    function deny(address deniedContract) public { 
+       44:+        onlyOperator();
+       45:+        contractAllowlist[deniedContract] = false; 
+       46:+    }
   39,  47: 
   40,  48:     /**
   41,  49:     @notice Checks if a borrow is allowed

- src/DBR.sol:44

diff --git a/src/DBR.sol b/src/DBR.sol
index aab6daf..50428cd 100644
--- a/src/DBR.sol
+++ b/src/DBR.sol
@@ -41,16 +41,16 @@ contract DolaBorrowingRights {
   41,  41:         INITIAL_DOMAIN_SEPARATOR = computeDomainSeparator();
   42,  42:     }
   43,  43: 
-  44     :-    modifier onlyOperator {
+       44:+    function onlyOperator() private view {
   45,  45:         require(msg.sender == operator, "ONLY OPERATOR");
-  46     :-        _;
   47,  46:     }
   48,  47:     
   49,  48:     /**
   50,  49:     @notice Sets pending operator of the contract. Operator role must be claimed by the new oprator. Only callable by Operator.
   51,  50:     @param newOperator_ The address of the newOperator
   52,  51:     */
-  53     :-    function setPendingOperator(address newOperator_) public onlyOperator {
+       52:+    function setPendingOperator(address newOperator_) public {
+       53:+        onlyOperator();
   54,  54:         pendingOperator = newOperator_;
   55,  55:     }
   56,  56: 
@@ -59,7 +59,8 @@ contract DolaBorrowingRights {
   59,  59:      At 10000, the cost of replenishing 1 DBR is 1 DOLA in debt. Only callable by Operator.
   60,  60:     @param newReplenishmentPriceBps_ The new replen
   61,  61:     */
-  62     :-    function setReplenishmentPriceBps(uint newReplenishmentPriceBps_) public onlyOperator {
+       62:+    function setReplenishmentPriceBps(uint newReplenishmentPriceBps_) public {
+       63:+        onlyOperator();
   63,  64:         require(newReplenishmentPriceBps_ > 0, "replenishment price must be over 0");
   64,  65:         replenishmentPriceBps = newReplenishmentPriceBps_;
   65,  66:     }
@@ -78,7 +79,8 @@ contract DolaBorrowingRights {
   78,  79:     @notice Add a minter to the set of addresses allowed to mint DBR tokens. Only callable by Operator.
   79,  80:     @param minter_ The address of the new minter.
   80,  81:     */
-  81     :-    function addMinter(address minter_) public onlyOperator {
+       82:+    function addMinter(address minter_) public {
+       83:+        onlyOperator();
   82,  84:         minters[minter_] = true;
   83,  85:         emit AddMinter(minter_);
   84,  86:     }
@@ -87,7 +89,8 @@ contract DolaBorrowingRights {
   87,  89:     @notice Removes a minter from the set of addresses allowe to mint DBR tokens. Only callable by Operator.
   88,  90:     @param minter_ The address to be removed from the minter set.
   89,  91:     */
-  90     :-    function removeMinter(address minter_) public onlyOperator {
+       92:+    function removeMinter(address minter_) public {
+       93:+        onlyOperator();
   91,  94:         minters[minter_] = false;
   92,  95:         emit RemoveMinter(minter_);
   93,  96:     }
@@ -96,7 +99,8 @@ contract DolaBorrowingRights {
   96,  99:     @dev markets can be added but cannot be removed. A removed market would result in unrepayable debt for some users.
   97, 100:     @param market_ The address of the new market contract to be added.
   98, 101:     */
-  99     :-    function addMarket(address market_) public onlyOperator {
+      102:+    function addMarket(address market_) public {
+      103:+        onlyOperator();
  100, 104:         markets[market_] = true;
  101, 105:         emit AddMarket(market_);
  102, 106:     }

- src/Market.sol:92

diff --git a/src/Market.sol b/src/Market.sol
index 9585b85..796d0d0 100644
--- a/src/Market.sol
+++ b/src/Market.sol
@@ -89,9 +89,8 @@ contract Market {
   89,  89:         INITIAL_DOMAIN_SEPARATOR = computeDomainSeparator();
   90,  90:     }
   91,  91:     
-  92     :-    modifier onlyGov {
+       92:+    function onlyGov() private view {
   93,  93:         require(msg.sender == gov, "Only gov can call this function");
-  94     :-        _;
   95,  94:     }
   96,  95: 
   97,  96:     function DOMAIN_SEPARATOR() public view virtual returns (bytes32) {
@@ -115,38 +114,54 @@ contract Market {
  115, 114:     @notice sets the oracle to a new oracle. Only callable by governance.
  116, 115:     @param _oracle The new oracle conforming to the IOracle interface.
  117, 116:     */
- 118     :-    function setOracle(IOracle _oracle) public onlyGov { oracle = _oracle; }
+      117:+    function setOracle(IOracle _oracle) public { 
+      118:+        onlyGov();
+      119:+        oracle = _oracle; 
+      120:+    }
  119, 121: 
  120, 122:     /**
  121, 123:     @notice sets the borrow controller to a new borrow controller. Only callable by governance.
  122, 124:     @param _borrowController The new borrow controller conforming to the IBorrowController interface.
  123, 125:     */
- 124     :-    function setBorrowController(IBorrowController _borrowController) public onlyGov { borrowController = _borrowController; }
+      126:+    function setBorrowController(IBorrowController _borrowController) public { 
+      127:+        onlyGov();
+      128:+        borrowController = _borrowController; 
+      129:+    }
  125, 130: 
  126, 131:     /**
  127, 132:     @notice sets the address of governance. Only callable by governance.
  128, 133:     @param _gov Address of the new governance.
  129, 134:     */
- 130     :-    function setGov(address _gov) public onlyGov { gov = _gov; }
+      135:+    function setGov(address _gov) public { 
+      136:+        onlyGov();
+      137:+        gov = _gov; 
+      138:+    }
  131, 139: 
  132, 140:     /**
  133, 141:     @notice sets the lender to a new lender. The lender is allowed to recall dola from the contract. Only callable by governance.
  134, 142:     @param _lender Address of the new lender.
  135, 143:     */
- 136     :-    function setLender(address _lender) public onlyGov { lender = _lender; }
+      144:+    function setLender(address _lender) public { 
+      145:+        onlyGov();
+      146:+        lender = _lender; 
+      147:+    }
  137, 148: 
  138, 149:     /**
  139, 150:     @notice sets the pause guardian. The pause guardian can pause borrowing. Only callable by governance.
  140, 151:     @param _pauseGuardian Address of the new pauseGuardian.
  141, 152:     */
- 142     :-    function setPauseGuardian(address _pauseGuardian) public onlyGov { pauseGuardian = _pauseGuardian; }
+      153:+    function setPauseGuardian(address _pauseGuardian) public { 
+      154:+        onlyGov();
+      155:+        pauseGuardian = _pauseGuardian; 
+      156:+    }
  143, 157:     
  144, 158:     /**
  145, 159:     @notice sets the Collateral Factor requirement of the market as measured in basis points. 1 = 0.01%. Only callable by governance.
  146, 160:     @dev Collateral factor mus be set below 100%
  147, 161:     @param _collateralFactorBps The new collateral factor as measured in basis points. 
  148, 162:     */
- 149     :-    function setCollateralFactorBps(uint _collateralFactorBps) public onlyGov {
+      163:+    function setCollateralFactorBps(uint _collateralFactorBps) public  {
+      164:+        onlyGov();
  150, 165:         require(_collateralFactorBps < 10000, "Invalid collateral factor");
  151, 166:         collateralFactorBps = _collateralFactorBps;
  152, 167:     }
@@ -158,7 +173,8 @@ contract Market {
  158, 173:     @dev Must be set between 1 and 10000.
  159, 174:     @param _liquidationFactorBps The new liquidation factor in basis points. 1 = 0.01%/
  160, 175:     */
- 161     :-    function setLiquidationFactorBps(uint _liquidationFactorBps) public onlyGov {
+      176:+    function setLiquidationFactorBps(uint _liquidationFactorBps) public  {
+      177:+        onlyGov();
  162, 178:         require(_liquidationFactorBps > 0 && _liquidationFactorBps <= 10000, "Invalid liquidation factor");
  163, 179:         liquidationFactorBps = _liquidationFactorBps;
  164, 180:     }
@@ -169,7 +185,8 @@ contract Market {
  169, 185:     @dev Must be set between 1 and 10000.
  170, 186:     @param _replenishmentIncentiveBps The new replenishment incentive set in basis points. 1 = 0.01%
  171, 187:     */
- 172     :-    function setReplenismentIncentiveBps(uint _replenishmentIncentiveBps) public onlyGov {
+      188:+    function setReplenismentIncentiveBps(uint _replenishmentIncentiveBps) public {
+      189:+        onlyGov();
  173, 190:         require(_replenishmentIncentiveBps > 0 && _replenishmentIncentiveBps < 10000, "Invalid replenishment incentive");
  174, 191:         replenishmentIncentiveBps = _replenishmentIncentiveBps;
  175, 192:     }
@@ -180,7 +197,8 @@ contract Market {
  180, 197:     @dev Must be set between 0 and 10000 - liquidation fee.
  181, 198:     @param _liquidationIncentiveBps The new liqudation incentive set in basis points. 1 = 0.01% 
  182, 199:     */
- 183     :-    function setLiquidationIncentiveBps(uint _liquidationIncentiveBps) public onlyGov {
+      200:+    function setLiquidationIncentiveBps(uint _liquidationIncentiveBps) public {
+      201:+        onlyGov();
  184, 202:         require(_liquidationIncentiveBps > 0 && _liquidationIncentiveBps + liquidationFeeBps < 10000, "Invalid liquidation incentive");
  185, 203:         liquidationIncentiveBps = _liquidationIncentiveBps;
  186, 204:     }
@@ -191,7 +209,8 @@ contract Market {
  191, 209:     @dev Must be set between 0 and 10000 - liquidation factor.
  192, 210:     @param _liquidationFeeBps The new liquidation fee set in basis points. 1 = 0.01%
  193, 211:     */
- 194     :-    function setLiquidationFeeBps(uint _liquidationFeeBps) public onlyGov {
+      212:+    function setLiquidationFeeBps(uint _liquidationFeeBps) public {
+      213:+        onlyGov();
  195, 214:         require(_liquidationFeeBps > 0 && _liquidationFeeBps + liquidationIncentiveBps < 10000, "Invalid liquidation fee");
  196, 215:         liquidationFeeBps = _liquidationFeeBps;
  197, 216:     }

- src/Oracle.sol:35

diff --git a/src/Oracle.sol b/src/Oracle.sol
index 14338ed..3e7c608 100644
--- a/src/Oracle.sol
+++ b/src/Oracle.sol
@@ -32,16 +32,18 @@ contract Oracle {
   32,  32:         operator = _operator;
   33,  33:     }
   34,  34: 
-  35     :-    modifier onlyOperator {
+       35:+    function onlyOperator() private view {
   36,  36:         require(msg.sender == operator, "ONLY OPERATOR");
-  37     :-        _;
   38,  37:     }
   39,  38:     
   40,  39:     /**
   41,  40:     @notice Sets the pending operator of the oracle. Only callable by operator.
   42,  41:     @param newOperator_ The address of the pending operator.
   43,  42:     */
-  44     :-    function setPendingOperator(address newOperator_) public onlyOperator { pendingOperator = newOperator_; }
+       43:+    function setPendingOperator(address newOperator_) public { 
+       44:+        onlyOperator();
+       45:+        pendingOperator = newOperator_; 
+       46:+    }
   45,  47: 
   46,  48:     /**
   47,  49:     @notice Sets the price feed of a specific token address.
@@ -50,7 +52,10 @@ contract Oracle {
   50,  52:     @param feed The chainlink feed of the ERC20 token.
   51,  53:     @param tokenDecimals uint8 representing the decimal precision of the token
   52,  54:     */
-  53     :-    function setFeed(address token, IChainlinkFeed feed, uint8 tokenDecimals) public onlyOperator { feeds[token] = FeedData(feed, tokenDecimals); }
+       55:+    function setFeed(address token, IChainlinkFeed feed, uint8 tokenDecimals) public { 
+       56:+        onlyOperator();
+       57:+        feeds[token] = FeedData(feed, tokenDecimals); 
+       58:+    }
   54,  59: 
   55,  60:     /**
   56,  61:     @notice Sets a fixed price for a token
@@ -58,7 +63,10 @@ contract Oracle {
   58,  63:     @param token The address of the fixed price token
   59,  64:     @param price The fixed price of the token. Remember to account for decimal precision when setting this.
   60,  65:     */
-  61     :-    function setFixedPrice(address token, uint price) public onlyOperator { fixedPrices[token] = price; }
+       66:+    function setFixedPrice(address token, uint price) public { 
+       67:+        onlyOperator();
+       68:+        fixedPrices[token] = price; 
+       69:+    }
   62,  70: 
   63,  71:     /**
   64,  72:     @notice Claims the operator role. Only successfully callable by the pending operator.

---

3. Duplicated require()/revert() checks should be refactored to a modifier or function ( instances)

Deployment. Gas Saved: 114 932

Minimum Method Call. Gas Saved: -59

Average Method Call. Gas Saved: -284

Maximum Method Call. Gas Saved: -398

Overall gas change: -2 665 (-12.599%)

- src/Fed.sol:49, 58, 67, 76, 87, 88, 104, 105

diff --git a/src/Fed.sol b/src/Fed.sol
index 1e819bb..8b54676 100644
--- a/src/Fed.sol
+++ b/src/Fed.sol
@@ -41,12 +41,24 @@ contract Fed {
   41,  41:         supplyCeiling = _supplyCeiling;
   42,  42:     }
   43,  43: 
+       44:+    function is_gov() private view {
+       45:+        require(msg.sender == gov, "ONLY GOV");
+       46:+    }
+       47:+
+       48:+    function is_chair() private view {
+       49:+        require(msg.sender == chair, "ONLY CHAIR");
+       50:+    }
+       51:+
+       52:+    function is_supported_market(IMarket _market) private view {
+       53:+        require(dbr.markets(address(_market)), "UNSUPPORTED MARKET");
+       54:+    }
+       55:+
   44,  56:     /**
   45,  57:     @notice Change the governance of the Fed contact. Only callable by governance.
   46,  58:     @param _gov The address of the new governance contract
   47,  59:     */
   48,  60:     function changeGov(address _gov) public {
-  49     :-        require(msg.sender == gov, "ONLY GOV");
+       61:+        is_gov();
   50,  62:         gov = _gov;
   51,  63:     }
   52,  64: 
@@ -55,7 +67,7 @@ contract Fed {
   55,  67:     @param _supplyCeiling Amount to set the supply ceiling to
   56,  68:     */
   57,  69:     function changeSupplyCeiling(uint _supplyCeiling) public {
-  58     :-        require(msg.sender == gov, "ONLY GOV");
+       70:+        is_gov();
   59,  71:         supplyCeiling = _supplyCeiling;
   60,  72:     }
   61,  73: 
@@ -64,7 +76,7 @@ contract Fed {
   64,  76:     @param _chair Address of the new chair.
   65,  77:     */
   66,  78:     function changeChair(address _chair) public {
-  67     :-        require(msg.sender == gov, "ONLY GOV");
+       79:+        is_gov();
   68,  80:         chair = _chair;
   69,  81:     }
   70,  82: 
@@ -73,7 +85,7 @@ contract Fed {
   73,  85:     @dev Useful for immediately removing chair powers in case of a wallet compromise.
   74,  86:     */
   75,  87:     function resign() public {
-  76     :-        require(msg.sender == chair, "ONLY CHAIR");
+       88:+        is_chair();
   77,  89:         chair = address(0);
   78,  90:     }
   79,  91: 
@@ -84,8 +96,8 @@ contract Fed {
   84,  96:     @param amount The amount of DOLA to mint and supply to the market.
   85,  97:     */
   86,  98:     function expansion(IMarket market, uint amount) public {
-  87     :-        require(msg.sender == chair, "ONLY CHAIR");
-  88     :-        require(dbr.markets(address(market)), "UNSUPPORTED MARKET");
+       99:+        is_chair();
+      100:+        is_supported_market(market);
   89, 101:         require(market.borrowPaused() != true, "CANNOT EXPAND PAUSED MARKETS");
   90, 102:         dola.mint(address(market), amount);
   91, 103:         supplies[market] += amount;
@@ -101,8 +113,8 @@ contract Fed {
  101, 113:     @param amount The amount of DOLA to withdraw and burn.
  102, 114:     */
  103, 115:     function contraction(IMarket market, uint amount) public {
- 104     :-        require(msg.sender == chair, "ONLY CHAIR");
- 105     :-        require(dbr.markets(address(market)), "UNSUPPORTED MARKET");
+      116:+        is_chair();
+      117:+        is_supported_market(market);
  106, 118:         uint supply = supplies[market];
  107, 119:         require(amount <= supply, "AMOUNT TOO BIG"); // can't burn profits
  108, 120:         market.recall(amount);

- src/DBR.sol:171, 195, 373

diff --git a/src/DBR.sol b/src/DBR.sol
index aab6daf..625c422 100644
--- a/src/DBR.sol
+++ b/src/DBR.sol
@@ -46,6 +46,10 @@ contract DolaBorrowingRights {
   46,  46:         _;
   47,  47:     }
   48,  48:     
+       49:+    function is_balance_sufficient(address _user, uint256 amount) private view {
+       50:+        require(balanceOf(_user) >= amount, "Insufficient balance");
+       51:+    }
+       52:+
   49,  53:     /**
   50,  54:     @notice Sets pending operator of the contract. Operator role must be claimed by the new oprator. Only callable by Operator.
   51,  55:     @param newOperator_ The address of the newOperator
@@ -168,7 +172,7 @@ contract DolaBorrowingRights {
  168, 172:     @return Always returns true, will revert if not successful.
  169, 173:     */
  170, 174:     function transfer(address to, uint256 amount) public virtual returns (bool) {
- 171     :-        require(balanceOf(msg.sender) >= amount, "Insufficient balance");
+      175:+        is_balance_sufficient(msg.sender, amount);
  172, 176:         balances[msg.sender] -= amount;
  173, 177:         unchecked {
  174, 178:             balances[to] += amount;
@@ -192,7 +196,7 @@ contract DolaBorrowingRights {
  192, 196:     ) public virtual returns (bool) {
  193, 197:         uint256 allowed = allowance[from][msg.sender];
  194, 198:         if (allowed != type(uint256).max) allowance[from][msg.sender] = allowed - amount;
- 195     :-        require(balanceOf(from) >= amount, "Insufficient balance");
+      199:+        is_balance_sufficient(from, amount);
  196, 200:         balances[from] -= amount;
  197, 201:         unchecked {
  198, 202:             balances[to] += amount;
@@ -370,7 +374,7 @@ contract DolaBorrowingRights {
  370, 374:     @param amount Amount of DBR to be burned.
  371, 375:     */
  372, 376:     function _burn(address from, uint256 amount) internal virtual {
- 373     :-        require(balanceOf(from) >= amount, "Insufficient balance");
+      377:+        is_balance_sufficient(from, amount);
  374, 378:         balances[from] -= amount;
  375, 379:         unchecked {
  376, 380:             _totalSupply -= amount;

---

4. Multiple address mappings can be combined into a single mapping of an address to a struct, where appropriate (5 instances)

Deployment. Gas Saved: 24 227

Minimum Method Call. Gas Saved: 254

Average Method Call. Gas Saved: 533

Maximum Method Call. Gas Saved: -6 726

Overall gas change: -1 371 (20.741%)

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.

- src/DBR.sol:19, 23, 26, 27, 28

diff --git a/src/DBR.sol b/src/DBR.sol
index aab6daf..43db0aa 100644
--- a/src/DBR.sol
+++ b/src/DBR.sol
@@ -8,6 +8,17 @@ pragma solidity ^0.8.13;
    8,   8: */
    9,   9: contract DolaBorrowingRights {
   10,  10: 
+       11:+    struct UserInfo {
+       12:+        uint256 balances;
+       13:+        
+       14:+        uint256 nonce;
+       15:+        uint256 debts;  // user => debt across all tracked markets
+       16:+        uint256 dueTokensAccrued; // user => amount of due tokens accrued
+       17:+        uint256 lastUpdated; // user => last update timestamp
+       18:+    }
+       19:+    
+       20:+    mapping(address => mapping(address => uint256)) public allowance;
+       21:+
   11,  22:     string public name;
   12,  23:     string public symbol;
   13,  24:     uint8 public constant decimals = 18;
@@ -16,16 +27,11 @@ contract DolaBorrowingRights {
   16,  27:     address public pendingOperator;
   17,  28:     uint public totalDueTokensAccrued;
   18,  29:     uint public replenishmentPriceBps;
-  19     :-    mapping(address => uint256) public balances;
-  20     :-    mapping(address => mapping(address => uint256)) public allowance;
+       30:+    mapping(address => UserInfo) public userInfo;
   21,  31:     uint256 internal immutable INITIAL_CHAIN_ID;
   22,  32:     bytes32 internal immutable INITIAL_DOMAIN_SEPARATOR;
-  23     :-    mapping(address => uint256) public nonces;
   24,  33:     mapping (address => bool) public minters;
   25,  34:     mapping (address => bool) public markets;
-  26     :-    mapping (address => uint) public debts; // user => debt across all tracked markets
-  27     :-    mapping (address => uint) public dueTokensAccrued; // user => amount of due tokens accrued
-  28     :-    mapping (address => uint) public lastUpdated; // user => last update timestamp
   29,  35: 
   30,  36:     constructor(
   31,  37:         uint _replenishmentPriceBps,
@@ -118,10 +124,10 @@ contract DolaBorrowingRights {
  118, 124:     @return uint representing the balance of the user.
  119, 125:     */
  120, 126:     function balanceOf(address user) public view returns (uint) {
- 121     :-        uint debt = debts[user];
- 122     :-        uint accrued = (block.timestamp - lastUpdated[user]) * debt / 365 days;
- 123     :-        if(dueTokensAccrued[user] + accrued > balances[user]) return 0;
- 124     :-        return balances[user] - dueTokensAccrued[user] - accrued;
+      127:+        uint debt = userInfo[user].debts;
+      128:+        uint accrued = (block.timestamp - userInfo[user].lastUpdated) * debt / 365 days;
+      129:+        if(userInfo[user].dueTokensAccrued + accrued > userInfo[user].balances) return 0;
+      130:+        return userInfo[user].balances - userInfo[user].dueTokensAccrued - accrued;
  125, 131:     }
  126, 132: 
  127, 133:     /**
@@ -131,10 +137,10 @@ contract DolaBorrowingRights {
  131, 137:     @return uint representing the deficit of the user.
  132, 138:     */
  133, 139:     function deficitOf(address user) public view returns (uint) {
- 134     :-        uint debt = debts[user];
- 135     :-        uint accrued = (block.timestamp - lastUpdated[user]) * debt / 365 days;
- 136     :-        if(dueTokensAccrued[user] + accrued < balances[user]) return 0;
- 137     :-        return dueTokensAccrued[user] + accrued - balances[user];
+      140:+        uint debt = userInfo[user].debts;
+      141:+        uint accrued = (block.timestamp - userInfo[user].lastUpdated) * debt / 365 days;
+      142:+        if(userInfo[user].dueTokensAccrued + accrued < userInfo[user].balances) return 0;
+      143:+        return userInfo[user].dueTokensAccrued + accrued - userInfo[user].balances;
  138, 144:     }
  139, 145:     
  140, 146:     /**
@@ -144,9 +150,9 @@ contract DolaBorrowingRights {
  144, 150:     @return Returns a signed int of the user's balance
  145, 151:     */
  146, 152:     function signedBalanceOf(address user) public view returns (int) {
- 147     :-        uint debt = debts[user];
- 148     :-        uint accrued = (block.timestamp - lastUpdated[user]) * debt / 365 days;
- 149     :-        return int(balances[user]) - int(dueTokensAccrued[user]) - int(accrued);
+      153:+        uint debt = userInfo[user].debts;
+      154:+        uint accrued = (block.timestamp - userInfo[user].lastUpdated) * debt / 365 days;
+      155:+        return int(userInfo[user].balances) - int(userInfo[user].dueTokensAccrued) - int(accrued);
  150, 156:     }
  151, 157: 
  152, 158:     /**
@@ -169,9 +175,9 @@ contract DolaBorrowingRights {
  169, 175:     */
  170, 176:     function transfer(address to, uint256 amount) public virtual returns (bool) {
  171, 177:         require(balanceOf(msg.sender) >= amount, "Insufficient balance");
- 172     :-        balances[msg.sender] -= amount;
+      178:+        userInfo[msg.sender].balances -= amount;
  173, 179:         unchecked {
- 174     :-            balances[to] += amount;
+      180:+            userInfo[to].balances += amount;
  175, 181:         }
  176, 182:         emit Transfer(msg.sender, to, amount);
  177, 183:         return true;
@@ -193,9 +199,9 @@ contract DolaBorrowingRights {
  193, 199:         uint256 allowed = allowance[from][msg.sender];
  194, 200:         if (allowed != type(uint256).max) allowance[from][msg.sender] = allowed - amount;
  195, 201:         require(balanceOf(from) >= amount, "Insufficient balance");
- 196     :-        balances[from] -= amount;
+      202:+        userInfo[from].balances -= amount;
  197, 203:         unchecked {
- 198     :-            balances[to] += amount;
+      204:+            userInfo[to].balances += amount;
  199, 205:         }
  200, 206:         emit Transfer(from, to, amount);
  201, 207:         return true;
@@ -236,7 +242,7 @@ contract DolaBorrowingRights {
  236, 242:                                 owner,
  237, 243:                                 spender,
  238, 244:                                 value,
- 239     :-                                nonces[owner]++,
+      245:+                                userInfo[owner].nonce++,
  240, 246:                                 deadline
  241, 247:                             )
  242, 248:                         )
@@ -256,7 +262,7 @@ contract DolaBorrowingRights {
  256, 262:     @notice Function for invalidating the nonce of a signed message.
  257, 263:     */
  258, 264:     function invalidateNonce() public {
- 259     :-        nonces[msg.sender]++;
+      265:+        userInfo[msg.sender].nonce++;
  260, 266:     }
  261, 267: 
  262, 268:     function DOMAIN_SEPARATOR() public view virtual returns (bytes32) {
@@ -282,12 +288,12 @@ contract DolaBorrowingRights {
  282, 288:     @param user The address of the user to accrue DBR debt to.
  283, 289:     */
  284, 290:     function accrueDueTokens(address user) public {
- 285     :-        uint debt = debts[user];
- 286     :-        if(lastUpdated[user] == block.timestamp) return;
- 287     :-        uint accrued = (block.timestamp - lastUpdated[user]) * debt / 365 days;
- 288     :-        dueTokensAccrued[user] += accrued;
+      291:+        uint debt = userInfo[user].debts;
+      292:+        if(userInfo[user].lastUpdated == block.timestamp) return;
+      293:+        uint accrued = (block.timestamp - userInfo[user].lastUpdated) * debt / 365 days;
+      294:+        userInfo[user].dueTokensAccrued += accrued;
  289, 295:         totalDueTokensAccrued += accrued;
- 290     :-        lastUpdated[user] = block.timestamp;
+      296:+        userInfo[user].lastUpdated = block.timestamp;
  291, 297:         emit Transfer(user, address(0), accrued);
  292, 298:     }
  293, 299: 
@@ -301,7 +307,7 @@ contract DolaBorrowingRights {
  301, 307:         require(markets[msg.sender], "Only markets can call onBorrow");
  302, 308:         accrueDueTokens(user);
  303, 309:         require(deficitOf(user) == 0, "DBR Deficit");
- 304     :-        debts[user] += additionalDebt;
+      310:+        userInfo[user].debts += additionalDebt;
  305, 311:     }
  306, 312: 
  307, 313:     /**
@@ -313,7 +319,7 @@ contract DolaBorrowingRights {
  313, 319:     function onRepay(address user, uint repaidDebt) public {
  314, 320:         require(markets[msg.sender], "Only markets can call onRepay");
  315, 321:         accrueDueTokens(user);
- 316     :-        debts[user] -= repaidDebt;
+      322:+        userInfo[user].debts -= repaidDebt;
  317, 323:     }
  318, 324: 
  319, 325:     /**
@@ -329,7 +335,7 @@ contract DolaBorrowingRights {
  329, 335:         require(deficit >= amount, "Amount > deficit");
  330, 336:         uint replenishmentCost = amount * replenishmentPriceBps / 10000;
  331, 337:         accrueDueTokens(user);
- 332     :-        debts[user] += replenishmentCost;
+      338:+        userInfo[user].debts += replenishmentCost;
  333, 339:         _mint(user, amount);
  334, 340:     }
  335, 341: 
@@ -359,7 +365,7 @@ contract DolaBorrowingRights {
  359, 365:     function _mint(address to, uint256 amount) internal virtual {
  360, 366:         _totalSupply += amount;
  361, 367:         unchecked {
- 362     :-            balances[to] += amount;
+      368:+            userInfo[to].balances += amount;
  363, 369:         }
  364, 370:         emit Transfer(address(0), to, amount);
  365, 371:     }
@@ -371,7 +377,7 @@ contract DolaBorrowingRights {
  371, 377:     */
  372, 378:     function _burn(address from, uint256 amount) internal virtual {
  373, 379:         require(balanceOf(from) >= amount, "Insufficient balance");
- 374     :-        balances[from] -= amount;
+      380:+        userInfo[from].balances -= amount;
  375, 381:         unchecked {
  376, 382:             _totalSupply -= amount;
  377, 383:         }
diff --git a/src/test/DBR.t.sol b/src/test/DBR.t.sol
index 3988cf7..754bf7f 100644
--- a/src/test/DBR.t.sol
+++ b/src/test/DBR.t.sol
@@ -145,17 +145,19 @@ contract DBRTest is FiRMTest {
  145, 145:     }
  146, 146: 
  147, 147:     function test_invalidateNonce() public {
- 148     :-        assertEq(dbr.nonces(user), 0, "User nonce should be uninitialized");
+      148:+        (, uint256 nonce,,,) = dbr.userInfo(user);
+      149:+        assertEq(nonce, 0, "User nonce should be uninitialized");
  149, 150: 
  150, 151:         vm.startPrank(user);
  151, 152:         dbr.invalidateNonce();
  152, 153: 
- 153     :-        assertEq(dbr.nonces(user), 1, "User nonce was not invalidated");
+      154:+        (,nonce,,,) = dbr.userInfo(user);
+      155:+        assertEq(nonce, 1, "User nonce was not invalidated");
  154, 156:     }
  155, 157: 
  156, 158:     function test_approve_increasesAllowanceByAmount() public {
  157, 159:         uint amount = 100e18;
- 158     :-
+      160:+        
  159, 161:         assertEq(dbr.allowance(user, gov), 0, "Allowance should not be set yet");
  160, 162: 
  161, 163:         vm.startPrank(user);

---

5. Expression can be unchecked when overflow is not possible (6 instances)

Deployment. Gas Saved: 20 220

Minimum Method Call. Gas Saved: 410

Average Method Call. Gas Saved: 4 630

Maximum Method Call. Gas Saved: 1 354

Overall gas change: -6 233 (-5.326%)

- src/DBR.sol:110, 124, 137, 259

diff --git a/src/DBR.sol b/src/DBR.sol
index aab6daf..0781c97 100644
--- a/src/DBR.sol
+++ b/src/DBR.sol
@@ -107,8 +107,10 @@ contract DolaBorrowingRights {
  107, 107:     @return uint representing the total supply of DBR.
  108, 108:     */
  109, 109:     function totalSupply() public view returns (uint) {
- 110     :-        if(totalDueTokensAccrued > _totalSupply) return 0;
- 111     :-        return _totalSupply - totalDueTokensAccrued;
+      110:+        unchecked {
+      111:+            if(totalDueTokensAccrued > _totalSupply) return 0;
+      112:+            return _totalSupply - totalDueTokensAccrued;
+      113:+        }
  112, 114:     }
  113, 115: 
  114, 116:     /**
@@ -121,7 +123,7 @@ contract DolaBorrowingRights {
  121, 123:         uint debt = debts[user];
  122, 124:         uint accrued = (block.timestamp - lastUpdated[user]) * debt / 365 days;
  123, 125:         if(dueTokensAccrued[user] + accrued > balances[user]) return 0;
- 124     :-        return balances[user] - dueTokensAccrued[user] - accrued;
+      126:+        unchecked { return balances[user] - dueTokensAccrued[user] - accrued; }
  125, 127:     }
  126, 128: 
  127, 129:     /**
@@ -134,7 +136,7 @@ contract DolaBorrowingRights {
  134, 136:         uint debt = debts[user];
  135, 137:         uint accrued = (block.timestamp - lastUpdated[user]) * debt / 365 days;
  136, 138:         if(dueTokensAccrued[user] + accrued < balances[user]) return 0;
- 137     :-        return dueTokensAccrued[user] + accrued - balances[user];
+      139:+        unchecked { return dueTokensAccrued[user] + accrued - balances[user]; }
  138, 140:     }
  139, 141:     
  140, 142:     /**
@@ -256,7 +258,7 @@ contract DolaBorrowingRights {
  256, 258:     @notice Function for invalidating the nonce of a signed message.
  257, 259:     */
  258, 260:     function invalidateNonce() public {
- 259     :-        nonces[msg.sender]++;
+      261:+        unchecked { nonces[msg.sender]++; }
  260, 262:     }
  261, 263: 
  262, 264:     function DOMAIN_SEPARATOR() public view virtual returns (bytes32) {

- src/Fed.sol:124

diff --git a/src/Fed.sol b/src/Fed.sol
index 1e819bb..b57b444 100644
--- a/src/Fed.sol
+++ b/src/Fed.sol
@@ -121,7 +121,7 @@ contract Fed {
  121, 121:         uint marketValue = dola.balanceOf(address(market)) + market.totalDebt();
  122, 122:         uint supply = supplies[market];
  123, 123:         if(supply >= marketValue) return 0;
- 124     :-        return marketValue - supply;
+      124:+        unchecked { return marketValue - supply; }
  125, 125:     }
  126, 126: 
  127, 127:     /**

- src/Market.sol:521

diff --git a/src/Market.sol b/src/Market.sol
index 9585b85..293bbb6 100644
--- a/src/Market.sol
+++ b/src/Market.sol
@@ -518,7 +518,7 @@ contract Market {
  518, 518:     @notice Function for incrementing the nonce of the msg.sender, making their latest signed message unusable.
  519, 519:     */
  520, 520:     function invalidateNonce() public {
- 521     :-        nonces[msg.sender]++;
+      521:+        unchecked { nonces[msg.sender]++; }
  522, 522:     }
  523, 523:     
  524, 524:     /**

---

6. State variables can be packed into fewer storage slots (1 instance)

Deployment. Gas Saved: -5 008

Minimum Method Call. Gas Saved: 1 911

Average Method Call. Gas Saved: 15 525

Maximum Method Call. Gas Saved: 20 972

Overall gas change: -62 419 (-69.524%)

If variables occupying the same slot are both written the same function or by the constructor, avoids a separate Gsset (20000 gas). Reads of the variables can also be cheaper

uint256(32), mapping(32), address(20), bool(1)

- src/Market.sol:53

diff --git a/src/Market.sol b/src/Market.sol
index 9585b85..6141e5c 100644
--- a/src/Market.sol
+++ b/src/Market.sol
@@ -36,6 +36,7 @@ interface IBorrowController {
   36,  36: contract Market {
   37,  37: 
   38,  38:     address public gov;
+       39:+    bool public borrowPaused;
   39,  40:     address public lender;
   40,  41:     address public pauseGuardian;
   41,  42:     address public immutable escrowImplementation;
@@ -50,7 +51,6 @@ contract Market {
   50,  51:     uint public liquidationFeeBps;
   51,  52:     uint public liquidationFactorBps = 5000; // 50% by default
   52,  53:     bool immutable callOnDepositCallback;
-  53     :-    bool public borrowPaused;
   54,  54:     uint public totalDebt;
   55,  55:     uint256 internal immutable INITIAL_CHAIN_ID;
   56,  56:     bytes32 internal immutable INITIAL_DOMAIN_SEPARATOR;

---

7. refactoring similar statements (1 instance)

Deployment. Gas Saved: 18 422

Minimum Method Call. Gas Saved: -18

Average Method Call. Gas Saved: -11

Maximum Method Call. Gas Saved: 6

Overall gas change: 4 876 (7.739%)

- src/Market.sol:213

diff --git a/src/Market.sol b/src/Market.sol
index 9585b85..da295e5 100644
--- a/src/Market.sol
+++ b/src/Market.sol
@@ -210,11 +210,9 @@ contract Market {
  210, 210:     @param _value Boolean representing the state pause state of borrows. true = paused, false = unpaused.
  211, 211:     */
  212, 212:     function pauseBorrows(bool _value) public {
- 213     :-        if(_value) {
- 214     :-            require(msg.sender == pauseGuardian || msg.sender == gov, "Only pause guardian or governance can pause");
- 215     :-        } else {
- 216     :-            require(msg.sender == gov, "Only governance can unpause");
- 217     :-        }
+      213:+        require(
+      214:+            ( _value && msg.sender == pauseGuardian) || msg.sender == gov,
+      215:+            "Only pause guardian or governance can pause");
  218, 216:         borrowPaused = _value;
  219, 217:     }
  220, 218: 
diff --git a/src/test/Market.t.sol b/src/test/Market.t.sol
index 8992ab9..86af449 100644
--- a/src/test/Market.t.sol
+++ b/src/test/Market.t.sol
@@ -16,7 +16,7 @@ import "./mocks/BorrowContract.sol";
   16,  16: import {EthFeed} from "./mocks/EthFeed.sol";
   17,  17: 
   18,  18: contract MarketTest is FiRMTest {
-  19     :-    bytes onlyGovUnpause = "Only governance can unpause";
+       19:+    bytes onlyGovUnpause = "Only pause guardian or governance can pause";
   20,  20:     bytes onlyPauseGuardianOrGov = "Only pause guardian or governance can pause";
   21,  21: 
   22,  22:     BorrowContract borrowContract;

---

8. Better algorithm for underflow check (3 instances)

Deployment. Gas Saved: 12 613

Minimum Method Call. Gas Saved: 656

Average Method Call. Gas Saved: 8 332

Maximum Method Call. Gas Saved: 3 741

Overall gas change: -18 048 (-15.981%)

- src/DBR.sol:110, 123, 136

diff --git a/src/DBR.sol b/src/DBR.sol
index aab6daf..bff9fef 100644
--- a/src/DBR.sol
+++ b/src/DBR.sol
@@ -104,37 +104,39 @@ contract DolaBorrowingRights {
  104, 104:     /**
  105, 105:     @notice Get the total supply of DBR tokens.
  106, 106:     @dev The total supply is calculated as the difference between total DBR minted and total DBR accrued.
- 107     :-    @return uint representing the total supply of DBR.
+      107:+    @return ret uint representing the total supply of DBR.
  108, 108:     */
- 109     :-    function totalSupply() public view returns (uint) {
- 110     :-        if(totalDueTokensAccrued > _totalSupply) return 0;
- 111     :-        return _totalSupply - totalDueTokensAccrued;
+      109:+    function totalSupply() public view returns (uint ret) {
+      110:+        unchecked { ret = _totalSupply - totalDueTokensAccrued; }
+      111:+        if(ret > _totalSupply) return 0;
  112, 112:     }
  113, 113: 
  114, 114:     /**
  115, 115:     @notice Get the DBR balance of an address. Will return 0 if the user has zero DBR or a deficit.
  116, 116:     @dev The balance of a user is calculated as the difference between the user's balance and the user's accrued DBR debt + due DBR debt.
  117, 117:     @param user Address of the user.
- 118     :-    @return uint representing the balance of the user.
+      118:+    @return ret uint representing the balance of the user.
  119, 119:     */
- 120     :-    function balanceOf(address user) public view returns (uint) {
+      120:+    function balanceOf(address user) public view returns (uint ret) {
  121, 121:         uint debt = debts[user];
  122, 122:         uint accrued = (block.timestamp - lastUpdated[user]) * debt / 365 days;
- 123     :-        if(dueTokensAccrued[user] + accrued > balances[user]) return 0;
- 124     :-        return balances[user] - dueTokensAccrued[user] - accrued;
+      123:+        uint mid = dueTokensAccrued[user] + accrued;
+      124:+        unchecked { ret = balances[user] - mid; }
+      125:+        if(ret > balances[user]) return 0;
  125, 126:     }
  126, 127: 
  127, 128:     /**
  128, 129:     @notice Get the DBR deficit of an address. Will return 0 if th user has zero DBR or more.
  129, 130:     @dev The deficit of a user is calculated as the difference between the user's accrued DBR deb + due DBR debt and their balance.
  130, 131:     @param user Address of the user.
- 131     :-    @return uint representing the deficit of the user.
+      132:+    @return ret uint representing the deficit of the user.
  132, 133:     */
- 133     :-    function deficitOf(address user) public view returns (uint) {
+      134:+    function deficitOf(address user) public view returns (uint ret) {
  134, 135:         uint debt = debts[user];
  135, 136:         uint accrued = (block.timestamp - lastUpdated[user]) * debt / 365 days;
- 136     :-        if(dueTokensAccrued[user] + accrued < balances[user]) return 0;
- 137     :-        return dueTokensAccrued[user] + accrued - balances[user];
+      137:+        uint mid = dueTokensAccrued[user] + accrued;
+      138:+        unchecked { ret = mid - balances[user]; }
+      139:+        if(mid < ret) return 0;
  138, 140:     }
  139, 141:     
  140, 142:     /**

---

9. x = x + y is cheaper than x += y (12 instances)

Deployment. Gas Saved: 11 214

Minimum Method Call. Gas Saved: 180

Average Method Call. Gas Saved: 468

Maximum Method Call. Gas Saved: 616

Overall gas change: -5 325 (-1.318%)

- src/DBR.sol:174, 196, 289, 360, 362, 376

diff --git a/src/DBR.sol b/src/DBR.sol
index aab6daf..c02b782 100644
--- a/src/DBR.sol
+++ b/src/DBR.sol
@@ -171,7 +171,7 @@ contract DolaBorrowingRights {
  171, 171:         require(balanceOf(msg.sender) >= amount, "Insufficient balance");
  172, 172:         balances[msg.sender] -= amount;
  173, 173:         unchecked {
- 174     :-            balances[to] += amount;
+      174:+            balances[to] = balances[to] + amount;
  175, 175:         }
  176, 176:         emit Transfer(msg.sender, to, amount);
  177, 177:         return true;
@@ -193,7 +193,7 @@ contract DolaBorrowingRights {
  193, 193:         uint256 allowed = allowance[from][msg.sender];
  194, 194:         if (allowed != type(uint256).max) allowance[from][msg.sender] = allowed - amount;
  195, 195:         require(balanceOf(from) >= amount, "Insufficient balance");
- 196     :-        balances[from] -= amount;
+      196:+        balances[from] = balances[from] - amount;
  197, 197:         unchecked {
  198, 198:             balances[to] += amount;
  199, 199:         }
@@ -286,7 +286,7 @@ contract DolaBorrowingRights {
  286, 286:         if(lastUpdated[user] == block.timestamp) return;
  287, 287:         uint accrued = (block.timestamp - lastUpdated[user]) * debt / 365 days;
  288, 288:         dueTokensAccrued[user] += accrued;
- 289     :-        totalDueTokensAccrued += accrued;
+      289:+        totalDueTokensAccrued = totalDueTokensAccrued + accrued;
  290, 290:         lastUpdated[user] = block.timestamp;
  291, 291:         emit Transfer(user, address(0), accrued);
  292, 292:     }
@@ -357,9 +357,9 @@ contract DolaBorrowingRights {
  357, 357:     @param amount Amount of DBR to mint.
  358, 358:     */
  359, 359:     function _mint(address to, uint256 amount) internal virtual {
- 360     :-        _totalSupply += amount;
+      360:+        _totalSupply = _totalSupply + amount;
  361, 361:         unchecked {
- 362     :-            balances[to] += amount;
+      362:+            balances[to] = balances[to] + amount;
  363, 363:         }
  364, 364:         emit Transfer(address(0), to, amount);
  365, 365:     }
@@ -373,7 +373,7 @@ contract DolaBorrowingRights {
  373, 373:         require(balanceOf(from) >= amount, "Insufficient balance");
  374, 374:         balances[from] -= amount;
  375, 375:         unchecked {
- 376     :-            _totalSupply -= amount;
+      376:+            _totalSupply = _totalSupply - amount;
  377, 377:         }
  378, 378:         emit Transfer(from, address(0), amount);
  379, 379:     }

- src/Market.sol:395, 397, 535, 568, 598, 600

diff --git a/src/Market.sol b/src/Market.sol
index 9585b85..bc0ff93 100644
--- a/src/Market.sol
+++ b/src/Market.sol
@@ -392,9 +392,9 @@ contract Market {
  392, 392:             require(borrowController.borrowAllowed(msg.sender, borrower, amount), "Denied by borrow controller");
  393, 393:         }
  394, 394:         uint credit = getCreditLimitInternal(borrower);
- 395     :-        debts[borrower] += amount;
+      395:+        debts[borrower] = debts[borrower] + amount;
  396, 396:         require(credit >= debts[borrower], "Exceeded credit limit");
- 397     :-        totalDebt += amount;
+      397:+        totalDebt = totalDebt + amount;
  398, 398:         dbr.onBorrow(borrower, amount);
  399, 399:         dola.transfer(to, amount);
  400, 400:         emit Borrow(borrower, amount);
@@ -532,7 +532,7 @@ contract Market {
  532, 532:         uint debt = debts[user];
  533, 533:         require(debt >= amount, "Insufficient debt");
  534, 534:         debts[user] -= amount;
- 535     :-        totalDebt -= amount;
+      535:+        totalDebt = totalDebt - amount;
  536, 536:         dbr.onRepay(user, amount);
  537, 537:         dola.transferFrom(msg.sender, address(this), amount);
  538, 538:         emit Repay(user, msg.sender, amount);
@@ -565,7 +565,7 @@ contract Market {
  565, 565:         debts[user] += replenishmentCost;
  566, 566:         uint collateralValue = getCollateralValueInternal(user);
  567, 567:         require(collateralValue >= debts[user], "Exceeded collateral value");
- 568     :-        totalDebt += replenishmentCost;
+      568:+        totalDebt = totalDebt + replenishmentCost;
  569, 569:         dbr.onForceReplenish(user, amount);
  570, 570:         dola.transfer(msg.sender, replenisherReward);
  571, 571:         emit ForceReplenish(user, msg.sender, amount, replenishmentCost, replenisherReward);
@@ -595,9 +595,9 @@ contract Market {
  595, 595:         require(repaidDebt <= debt * liquidationFactorBps / 10000, "Exceeded liquidation factor");
  596, 596:         uint price = oracle.getPrice(address(collateral), collateralFactorBps);
  597, 597:         uint liquidatorReward = repaidDebt * 1 ether / price;
- 598     :-        liquidatorReward += liquidatorReward * liquidationIncentiveBps / 10000;
+      598:+        liquidatorReward = liquidatorReward + liquidatorReward * liquidationIncentiveBps / 10000;
  599, 599:         debts[user] -= repaidDebt;
- 600     :-        totalDebt -= repaidDebt;
+      600:+        totalDebt = totalDebt - repaidDebt;
  601, 601:         dbr.onRepay(user, repaidDebt);
  602, 602:         dola.transferFrom(msg.sender, address(this), repaidDebt);
  603, 603:         IEscrow escrow = predictEscrow(user);

---

10. internal functions only called once can be inlined to save gas (1 instance)

Deployment. Gas Saved: 5 207

Minimum Method Call. Gas Saved: 67

Average Method Call. Gas Saved: 47

Maximum Method Call. Gas Saved: 24

Overall gas change: -137 (-0.154%)

- src/DBR.sol:341

diff --git a/src/DBR.sol b/src/DBR.sol
index aab6daf..a357f92 100644
--- a/src/DBR.sol
+++ b/src/DBR.sol
@@ -338,7 +338,12 @@ contract DolaBorrowingRights {
  338, 338:     @param amount Amount to be burned
  339, 339:     */
  340, 340:     function burn(uint amount) public {
- 341     :-        _burn(msg.sender, amount);
+      341:+        require(balanceOf(msg.sender) >= amount, "Insufficient balance");
+      342:+        balances[msg.sender] -= amount;
+      343:+        unchecked {
+      344:+            _totalSupply -= amount;
+      345:+        }
+      346:+        emit Transfer(msg.sender, address(0), amount);
  342, 347:     }
  343, 348: 
  344, 349:     /**
@@ -364,20 +369,6 @@ contract DolaBorrowingRights {
  364, 369:         emit Transfer(address(0), to, amount);
  365, 370:     }
  366, 371: 
- 367     :-    /**
- 368     :-    @notice Internal function for burning DBR.
- 369     :-    @param from Address to burn DBR from.
- 370     :-    @param amount Amount of DBR to be burned.
- 371     :-    */
- 372     :-    function _burn(address from, uint256 amount) internal virtual {
- 373     :-        require(balanceOf(from) >= amount, "Insufficient balance");
- 374     :-        balances[from] -= amount;
- 375     :-        unchecked {
- 376     :-            _totalSupply -= amount;
- 377     :-        }
- 378     :-        emit Transfer(from, address(0), amount);
- 379     :-    }
- 380     :-
  381, 372:     event Transfer(address indexed from, address indexed to, uint256 amount);
  382, 373:     event Approval(address indexed owner, address indexed spender, uint256 amount);
  383, 374:     event AddMinter(address indexed minter);

---

11. State variables should be cached in stack variables rather than re-reading them from storage (2 instances)

Deployment. Gas Saved: 5 007

Minimum Method Call. Gas Saved: 478

Average Method Call. Gas Saved: 1 117

Maximum Method Call. Gas Saved: 1 423

Overall gas change: -6 231 (-1.618%)

- src/DBR.sol:286

diff --git a/src/DBR.sol b/src/DBR.sol
index aab6daf..c70fcd7 100644
--- a/src/DBR.sol
+++ b/src/DBR.sol
@@ -283,8 +283,9 @@ contract DolaBorrowingRights {
  283, 283:     */
  284, 284:     function accrueDueTokens(address user) public {
  285, 285:         uint debt = debts[user];
- 286     :-        if(lastUpdated[user] == block.timestamp) return;
- 287     :-        uint accrued = (block.timestamp - lastUpdated[user]) * debt / 365 days;
+      286:+        uint _lastUpdated = lastUpdated[user];
+      287:+        if(_lastUpdated == block.timestamp) return;
+      288:+        uint accrued = (block.timestamp - _lastUpdated) * debt / 365 days;
  288, 289:         dueTokensAccrued[user] += accrued;
  289, 290:         totalDueTokensAccrued += accrued;
  290, 291:         lastUpdated[user] = block.timestamp;

- src/Market.sol:391

diff --git a/src/Market.sol b/src/Market.sol
index 9585b85..5f3264d 100644
--- a/src/Market.sol
+++ b/src/Market.sol
@@ -388,8 +388,9 @@ contract Market {
  388, 388:     */
  389, 389:     function borrowInternal(address borrower, address to, uint amount) internal {
  390, 390:         require(!borrowPaused, "Borrowing is paused");
- 391     :-        if(borrowController != IBorrowController(address(0))) {
- 392     :-            require(borrowController.borrowAllowed(msg.sender, borrower, amount), "Denied by borrow controller");
+      391:+        IBorrowController _borrowController = borrowController;
+      392:+        if(_borrowController != IBorrowController(address(0))) {
+      393:+            require(_borrowController.borrowAllowed(msg.sender, borrower, amount), "Denied by borrow controller");
  393, 394:         }
  394, 395:         uint credit = getCreditLimitInternal(borrower);
  395, 396:         debts[borrower] += amount;

---

99. Overall gas savings

Deployment. Gas Saved: 416 802

Minimum Method Call. Gas Saved: 3 423

Average Method Call. Gas Saved: 15 773

Maximum Method Call. Gas Saved: 18 283

Overall gas change: -84 866 (-67.204%)

diff --git a/original.txt b/fixed.txt
index 15fe5a1..d8a52d4 100644
--- a/original.txt
+++ b/fixed.txt
 ╭────────────────────────────────────────────────────┬─────────────────┬───────┬────────┬───────┬─────────╮
 │ src/BorrowController.sol:BorrowController contract ┆                 ┆       ┆        ┆       ┆         │
 ╞════════════════════════════════════════════════════╪═════════════════╪═══════╪════════╪═══════╪═════════╡
 │ Deployment Cost                                    ┆ Deployment Size ┆       ┆        ┆       ┆         │
 ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
-│ 180951                                             ┆ 971             ┆       ┆        ┆       ┆         │
+│ 166939                                             ┆ 901             ┆       ┆        ┆       ┆         │
 ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
 │ Function Name                                      ┆ min             ┆ avg   ┆ median ┆ max   ┆ # calls │
 ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
-│ allow                                              ┆ 664             ┆ 19132 ┆ 22750  ┆ 24750 ┆ 5       │
+│ allow                                              ┆ 646             ┆ 19148 ┆ 22774  ┆ 24774 ┆ 5       │
 ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
 │ borrowAllowed                                      ┆ 624             ┆ 1761  ┆ 1807   ┆ 2807  ┆ 4       │
 ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
 │ contractAllowlist                                  ┆ 553             ┆ 1353  ┆ 553    ┆ 2553  ┆ 5       │
 ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
-│ deny                                               ┆ 576             ┆ 1972  ┆ 596    ┆ 4744  ┆ 3       │
+│ deny                                               ┆ 558             ┆ 1980  ┆ 615    ┆ 4768  ┆ 3       │
 ├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌
... See the rest this report [here](https://github.com/code-423n4/2022-10-inverse-findings/blob/main/data/pfapostol-G.md)

[c4-judge]

0xean marked the issue as grade-a

[c4-judge]

0xean marked the issue as selected for report