Gas Optimizations - Githubissues

[G-01] Use defualt value rather than overwriite variable with their default value.

Overriting varibles with defualt values with their default value will waste only gas and not necessary.

There are 7 instances of this issue:

File: BlurExchange.sol lines 199, 475, 476

for (uint8 i = 0; i < orders.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/BlurExchange.sol#L199

uint256 totalFee = 0;

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/BlurExchange.sol#L475

for (uint8 i = 0; i < fees.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/BlurExchange.sol#L476

File: PolicyManager.sol line 77

for (uint256 i = 0; i < length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/PolicyManager.sol#L77

File: EIP712.sol line 77

for (uint256 i = 0; i < fees.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/lib/EIP712.sol#L77

File: MarkleVarifier.sol line 38

for (uint256 i = 0; i < proof.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/lib/MerkleVerifier.sol#L38

File: ReentrancyGuarded.sol line 10

bool reentrancyLock = false;

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/lib/ReentrancyGuarded.sol#L10

[G-02] In for loop use outside variable for array length

For loop written like thisfor (uint256 i; i < array.length; ++i) { will cost more gas than for (uint256 i; i < _lengthOfArray; ++i) { because for every iteration we use mload and memory_offset that will cost about 6 gas

There are 4 instances of this issue:

File: BlurExchange.sol lines 199, 476

for (uint8 i = 0; i < orders.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/BlurExchange.sol#L199

for (uint8 i = 0; i < fees.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/BlurExchange.sol#L476

File: EIP712.sol line 77

for (uint256 i = 0; i < fees.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/lib/EIP712.sol#L77

File: MerkleVerifier.sol line 38

for (uint256 i = 0; i < proof.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/lib/MerkleVerifier.sol#L38

[G-03] Recommend to use short require string to save deployment gas

If you use longer require strings than 32 bytes that will cost more expensive than short require string.

There are 2 instances of this issue:

File: BlurExchange.sol line 482

require(totalFee <= price, "Total amount of fees are more than the price");

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/BlurExchange.sol#L482

File: ExecutionDelegate.sol line 22

require(contracts[msg.sender], "Contract is not approved to make transfers");

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/ExecutionDelegate.sol#L22

[G-04] i++, i += 1 and i = i + 1 IN FOR LOOPS COSTS MORE GAS COMPARED TO ++i

++i will save about 5 gas for each iteration

There are 5 instances of this issue:

File: BlurExchange.sol lines 199, 475, 476

for (uint8 i = 0; i < orders.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/BlurExchange.sol#L199

for (uint8 i = 0; i < fees.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/BlurExchange.sol#L476

File: PolicyManager.sol line 77

for (uint256 i = 0; i < length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/PolicyManager.sol#L77

File: EIP712.sol line 77

for (uint256 i = 0; i < fees.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/lib/EIP712.sol#L77

File: MarkleVarifier.sol line 38

for (uint256 i = 0; i < proof.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/lib/MerkleVerifier.sol#L38

[G-05] Use `uncheck()` in for loops whenere overflow and undeflow is not possible

Using of uncheck(i++)/uncheck(++i) will save about 30 gas per iteration because compiler not save check everytime. This feature come from 0.8

There are 5 instances of this issue:

File: BlurExchange.sol lines 199, 475, 476

for (uint8 i = 0; i < orders.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/BlurExchange.sol#L199

for (uint8 i = 0; i < fees.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/BlurExchange.sol#L476

File: PolicyManager.sol line 77

for (uint256 i = 0; i < length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/PolicyManager.sol#L77

File: EIP712.sol line 77

for (uint256 i = 0; i < fees.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/lib/EIP712.sol#L77

File: MarkleVarifier.sol line 38

for (uint256 i = 0; i < proof.length; i++) {

https://github.com/code-423n4/2022-10-blur/blob/2fdaa6e13b544c8c11d1c022a575f16c3a72e3bf/contracts/lib/MerkleVerifier.sol#L38

[G-06] Recomend to use `uint256(1)`/`uint256(2)` for true and false

If you don't use boolean for storage you will avoid Gwarmaccess 100 gas. Also boolean from true to false cost 20000 gas rather than uint256(2) to uint256(1) that cost less.

There have 5 istance of this issues:

File: BlurExchange.sol line 71

mapping(bytes32 => bool) public cancelledOrFilled;

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L71

File: ExecutionDelegate.sol lines 18, 19

mapping(address => bool) public contracts;

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/ExecutionDelegate.sol#L18

mapping(address => bool) public revokedApproval;

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/ExecutionDelegate.sol#L19

File: ReentrancyGuarded.sol line 10

bool reentrancyLock = false;

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/lib/ReentrancyGuarded.sol#L10

[G-07] Recomend to use one operator for comparison

If you use >= or <= this will cost more gas because in the EVM there is no implementation of Opcodes for >= and <=and two operations are done. You can use instead x < y + 1 or x + 1 > y and save some gas.

There have 3 istance of this issues:

File: BlurExchange.sol lines 168, 422, 482

sell.order.listingTime <= buy.order.listingTime ? sell.order.trader : buy.order.trader,

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L168

if (sell.listingTime <= buy.listingTime) {

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L422

require(totalFee <= price, "Total amount of fees are more than the price");

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L482

[G-08] = + cost less than += for state variables

There have 1 istance of this issues:

File: BlurExchange.sol line 479

totalFee += fee;

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L479

[G-09] Using of custom errors than are came from 0.8.4 instead of `require()`/`revert()` strings will save deployment gas

There have 10 istance of this issues:

File: BlurExchange.sol lines 36, 134, 139, 140, 142, 143, 183, 219, 228, 237, 318, 407, 424, 428, 431, 452, 482, 534

require(isOpen == 1, "Closed");

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L36

require(sell.order.side == Side.Sell);

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L134

require(_validateOrderParameters(sell.order, sellHash), "Sell has invalid parameters");

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L139

require(_validateOrderParameters(buy.order, buyHash), "Buy has invalid parameters");

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L140

require(_validateSignatures(sell, sellHash), "Sell failed authorization");

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L142

require(_validateSignatures(buy, buyHash), "Buy failed authorization");

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L143

require(msg.sender == order.trader);

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L183

require(address(_executionDelegate) != address(0), "Address cannot be zero");

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L219

require(address(_policyManager) != address(0), "Address cannot be zero");

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L228

  237:         require(_oracle != address(0), "Address cannot be zero");

https://github.com/code-423n4/2022-10-blur/blob/ad6c43bf2da2cee806e1dee20b6d05f651809ecc/contracts/BlurExchange.sol#L23

code-423n4 / 2022-10-blur-findings

Gas Optimizations #843

[G-01] Use defualt value rather than overwriite variable with their default value.

[G-02] In for loop use outside variable for array length

[G-03] Recommend to use short require string to save deployment gas

[G-04] i++, i += 1 and i = i + 1 IN FOR LOOPS COSTS MORE GAS COMPARED TO ++i

[G-05] Use `uncheck()` in for loops whenere overflow and undeflow is not possible

[G-06] Recomend to use `uint256(1)`/`uint256(2)` for true and false

[G-07] Recomend to use one operator for comparison

[G-08] = + cost less than += for state variables

[G-09] Using of custom errors than are came from 0.8.4 instead of `require()`/`revert()` strings will save deployment gas

code-423n4 / 2022-10-blur-findings

Gas Optimizations #843

[G-01] Use defualt value rather than overwriite variable with their default value.

[G-02] In for loop use outside variable for array length

[G-03] Recommend to use short require string to save deployment gas

[G-04] i++, i += 1 and i = i + 1 IN FOR LOOPS COSTS MORE GAS COMPARED TO ++i

[G-05] Use uncheck() in for loops whenere overflow and undeflow is not possible

[G-06] Recomend to use uint256(1)/uint256(2) for true and false

[G-07] Recomend to use one operator for comparison

[G-08] = + cost less than += for state variables

[G-09] Using of custom errors than are came from 0.8.4 instead of require()/revert() strings will save deployment gas

[G-05] Use `uncheck()` in for loops whenere overflow and undeflow is not possible

[G-06] Recomend to use `uint256(1)`/`uint256(2)` for true and false

[G-09] Using of custom errors than are came from 0.8.4 instead of `require()`/`revert()` strings will save deployment gas