Gas Optimizations

[code423n4]

1) ++var (--var) cost less gas than var++ (var--). post-increment/decrement cost more gas then pre-increment/decrement PuttyV2.sol line 556 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L556 for (uint256 i = 0; i < orders.length; i++) {

PuttyV2.sol line 594 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L594
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 611 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L611
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 627 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L627
    for (uint256 i = 0; i < floorTokens.length; i++) {

PuttyV2.sol line 637 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L637
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 647 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L647
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 658 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L658
    for (uint256 i = 0; i < floorTokens.length; i++) {

PuttyV2.sol line 670 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L670
    for (uint256 i = 0; i < whitelist.length; i++) {

PuttyV2.sol line 728 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L728
    for (uint256 i = 0; i < arr.length; i++) {

PuttyV2.sol line 742 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L742
    for (uint256 i = 0; i < arr.length; i++) {

2) Array length should not be looked up in every loop of a for-loop. Storage array length checks incur an extra Gwarmaccess (100 gas) per loop. Store the array length in a variable and use it in the for loop helps to save gas

PuttyV2.sol line 556 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L556
    for (uint256 i = 0; i < orders.length; i++) {

PuttyV2.sol line 594 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L594
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 611 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L611
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 627 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L627
    for (uint256 i = 0; i < floorTokens.length; i++) {

PuttyV2.sol line 637 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L637
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 647 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L647
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 658 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L658
    for (uint256 i = 0; i < floorTokens.length; i++) {

PuttyV2.sol line 670 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L670
    for (uint256 i = 0; i < whitelist.length; i++) {

PuttyV2.sol line 728 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L728
    for (uint256 i = 0; i < arr.length; i++) {

PuttyV2.sol line 742 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L742
    for (uint256 i = 0; i < arr.length; i++) {

3) != 0 is cheaper than >. Replace all != 0 for > 0 PuttyV2.sol line 293 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L293 require(order.baseAsset.code.length > 0, "baseAsset is not contract");

PuttyV2.sol line 327 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L327
    if (weth == order.baseAsset && msg.value > 0) {

PuttyV2.sol line 351 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L351
    if (weth == order.baseAsset && msg.value > 0) {

PuttyV2.sol line 427 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L427
    if (weth == order.baseAsset && msg.value > 0) {

PuttyV2.sol line 498 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L498
    if (fee > 0) {

PuttyV2.sol line 598 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L598
    require(token.code.length > 0, "ERC20: Token is not contract");

PuttyV2.sol line 599 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L599
    require(tokenAmount > 0, "ERC20: Amount too small");

4) DEfault value initialization. If a variable is not set/initialized, it is assumed to have the default value (0, false, ...). Explicitly initializizing it with its default value is an anti-pattern and wate gas. Change the following loops to not initilize the i variable. PuttyV2.sol line 556 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L556 for (uint256 i = 0; i < orders.length; i++) {

PuttyV2.sol line 594 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L594
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 611 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L611
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 627 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L627
    for (uint256 i = 0; i < floorTokens.length; i++) {

PuttyV2.sol line 637 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L637
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 647 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L647
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 658 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L658
    for (uint256 i = 0; i < floorTokens.length; i++) {

PuttyV2.sol line 670 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L670
    for (uint256 i = 0; i < whitelist.length; i++) {

PuttyV2.sol line 728 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L728
    for (uint256 i = 0; i < arr.length; i++) {

PuttyV2.sol line 742 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L742
    for (uint256 i = 0; i < arr.length; i++) {

5) Unchecked Arithmetic. The dafault "checked" behavior cost more gas than adding/diving/etc, because under-the-hood those checs are implemented as a series of opcodes that, prior to performing the actual arithmetic, check for under/overflow and revert if its detected. Change the i++ in all the loops to add an unchecked block with the ++i

PuttyV2.sol line 556 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L556
    for (uint256 i = 0; i < orders.length; i++) {

PuttyV2.sol line 594 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L594
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 611 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L611
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 627 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L627
    for (uint256 i = 0; i < floorTokens.length; i++) {

PuttyV2.sol line 637 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L637
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 647 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L647
    for (uint256 i = 0; i < assets.length; i++) {

PuttyV2.sol line 658 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L658
    for (uint256 i = 0; i < floorTokens.length; i++) {

PuttyV2.sol line 670 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L670
    for (uint256 i = 0; i < whitelist.length; i++) {

PuttyV2.sol line 728 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L728
    for (uint256 i = 0; i < arr.length; i++) {

PuttyV2.sol line 742 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L742
    for (uint256 i = 0; i < arr.length; i++) {

6) Expressions for constant values such as a call to KECCAK256 should use IMMUTABLE rather than constant. Change it in the following lines. https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L89 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L95 https://github.com/code-423n4/2022-06-putty/blob/3b6b844bc39e897bd0bbb69897f2deff12dc3893/contracts/src/PuttyV2.sol#L101