Putty contest - z3s's results

Gas Optimizations

[G01] state variables should be cached:

Caching will replace each SLOAD (100 gas) with a much cheaper stack read.

cache weth:

PuttyV2.sol::fillOrder()
  327,17:             if (weth == order.baseAsset && msg.value > 0) {
  335,23:                 IWETH(weth).deposit{value: msg.value}();
  336,23:                 IWETH(weth).transfer(order.maker, msg.value);
  351,17:             if (weth == order.baseAsset && msg.value > 0) {
  358,18:                 IWETH(weth).deposit{value: msg.value}();

PuttyV2.sol::exercise()
  427,17:             if (weth == order.baseAsset && msg.value > 0) {
  434,18:                 IWETH(weth).deposit{value: msg.value}();

cache fee:

PuttyV2.sol
  498,17:             if (fee > 0) {
  499,45:                 feeAmount = (order.strike * fee) / 1000;

[G02] ++i is cheaper than i++:

actually it's important in iterations. It's better to use unchecked { ++i; }

PuttyV2.sol
  556,39:         for (uint256 i = 0; i < orders.length; i++) {
  594,39:         for (uint256 i = 0; i < assets.length; i++) {
  611,39:         for (uint256 i = 0; i < assets.length; i++) {
  627,44:         for (uint256 i = 0; i < floorTokens.length; i++) {
  637,39:         for (uint256 i = 0; i < assets.length; i++) {
  647,39:         for (uint256 i = 0; i < assets.length; i++) {
  658,44:         for (uint256 i = 0; i < floorTokens.length; i++) {
  670,42:         for (uint256 i = 0; i < whitelist.length; i++) {
  728,36:         for (uint256 i = 0; i < arr.length; i++) {
  742,36:         for (uint256 i = 0; i < arr.length; i++) {

[G03] uint256 default value is 0 so we can remove = 0 for saving some gas:

PuttyV2.sol
  497,31:             uint256 feeAmount = 0;
  556,24:         for (uint256 i = 0; i < orders.length; i++) {
  594,24:         for (uint256 i = 0; i < assets.length; i++) {
  611,24:         for (uint256 i = 0; i < assets.length; i++) {
  627,24:         for (uint256 i = 0; i < floorTokens.length; i++) {
  637,24:         for (uint256 i = 0; i < assets.length; i++) {
  647,24:         for (uint256 i = 0; i < assets.length; i++) {
  658,24:         for (uint256 i = 0; i < floorTokens.length; i++) {
  670,24:         for (uint256 i = 0; i < whitelist.length; i++) {
  728,24:         for (uint256 i = 0; i < arr.length; i++) {
  742,24:         for (uint256 i = 0; i < arr.length; i++) {

[G04] cache <array>.length:

Even memory arrays incur the overhead of bit tests and bit shifts to calculate the array length.

PuttyV2.sol
  556,39:         for (uint256 i = 0; i < orders.length; i++) {
  594,39:         for (uint256 i = 0; i < assets.length; i++) {
  611,39:         for (uint256 i = 0; i < assets.length; i++) {
  627,44:         for (uint256 i = 0; i < floorTokens.length; i++) {
  637,39:         for (uint256 i = 0; i < assets.length; i++) {
  647,39:         for (uint256 i = 0; i < assets.length; i++) {
  658,44:         for (uint256 i = 0; i < floorTokens.length; i++) {
  670,42:         for (uint256 i = 0; i < whitelist.length; i++) {
  728,36:         for (uint256 i = 0; i < arr.length; i++) {
  742,36:         for (uint256 i = 0; i < arr.length; i++) {

[G05] Expressions for constant values such as a call to keccak256(), should use immutable rather than constant:

See this issue for a detail description of the issue

PuttyV2.sol
  90,9:         keccak256(abi.encodePacked("ERC721Asset(address token,uint256 tokenId)"));
  96,9:         keccak256(abi.encodePacked("ERC20Asset(address token,uint256 tokenAmount)"));
  102,9:         keccak256(

[G06] Use Custom Errors to save Gas:

Custom errors from Solidity 0.8.4 are cheaper than require messages. https://blog.soliditylang.org/2021/04/21/custom-errors/

PuttyV2.sol
  214,9:         require(_weth != address(0), "Unset weth address");
  241,9:         require(_fee < 30, "fee must be less than 3%");
  278,9:         require(SignatureChecker.isValidSignatureNow(order.maker, orderHash, signature), "Invalid signature");
  281,9:         require(!cancelledOrders[orderHash], "Order has been cancelled");
  284,9:         require(order.whitelist.length == 0 || isWhitelisted(order.whitelist, msg.sender), "Not whitelisted");
  287,9:         require(order.duration < 10_000 days, "Duration too long");
  290,9:         require(block.timestamp < order.expiration, "Order has expired");
  293,9:         require(order.baseAsset.code.length > 0, "baseAsset is not contract");
  297,15:             ? require(floorAssetTokenIds.length == order.floorTokens.length, "Wrong amount of floor tokenIds")
  298,15:             : require(floorAssetTokenIds.length == 0, "Invalid floor tokens length");
  329,17:                 require(msg.value == order.premium, "Incorrect ETH amount sent");
  353,17:                 require(msg.value == order.strike, "Incorrect ETH amount sent");
  395,9:         require(ownerOf(uint256(orderHash)) == msg.sender, "Not owner");
  398,9:         require(order.isLong, "Can only exercise long positions");
  401,9:         require(block.timestamp < positionExpirations[uint256(orderHash)], "Position has expired");
  405,15:             ? require(floorAssetTokenIds.length == order.floorTokens.length, "Wrong amount of floor tokenIds")
  406,15:             : require(floorAssetTokenIds.length == 0, "Invalid floor tokenIds length");
  429,17:                 require(msg.value == order.strike, "Incorrect ETH amount sent");
  470,9:         require(!order.isLong, "Must be short position");
  475,9:         require(ownerOf(uint256(orderHash)) == msg.sender, "Not owner");
  481,9:         require(block.timestamp > positionExpirations[longPositionId] || isExercised, "Must be exercised or expired");
  527,9:         require(msg.sender == order.maker, "Not your order");
  551,9:         require(orders.length == signatures.length, "Length mismatch in input");
  552,9:         require(signatures.length == floorAssetTokenIds.length, "Length mismatch in input");
  598,13:             require(token.code.length > 0, "ERC20: Token is not contract");
  599,13:             require(tokenAmount > 0, "ERC20: Amount too small");
  765,9:         require(_ownerOf[id] != address(0), "URI query for NOT_MINTED token");

PuttyV2Nft.sol
  12,9:         require(to != address(0), "INVALID_RECIPIENT");
  13,9:         require(_ownerOf[id] == address(0), "ALREADY_MINTED");
  26,9:         require(from == _ownerOf[id], "WRONG_FROM");
  27,9:         require(to != address(0), "INVALID_RECIPIENT");
  28,9:         require(
  41,9:         require(owner != address(0), "ZERO_ADDRESS");