1) .LENGTH SHOULD NOT BE LOOKED UP IN EVERY LOOP OF A FOR-LOOP and Increments can be unchecked

The overheads outlined below are PER LOOP, excluding the first loop

storage arrays incur a Gwarmaccess (100 gas) memory arrays use MLOAD (3 gas) calldata arrays use CALLDATALOAD (3 gas) ++I COSTS LESS GAS THAN I++ Caching the length changes each of these to a DUP (3 gas), and gets rid of the extra DUP needed to store the stack offset uint256 length = arr.length; For example for (uint i; i < length; ) { // do stuff unchecked { ++i; } } https://github.com/code-423n4/2022-10-blur/blob/main/contracts/BlurExchange.sol#L199 https://github.com/code-423n4/2022-10-blur/blob/main/contracts/BlurExchange.sol#L476 https://github.com/code-423n4/2022-10-blur/blob/main/contracts/lib/EIP712.sol#L77

2 USING CALL() INSTEAD OF TRANSFER() ON AN ADDRESS PAYABLE CAN SAVE GAS

The claimer smart contract does implement a payable fallback which uses more than 2300 gas unit. The claimer smart contract implements a payable fallback function that needs less than 2300 gas units but is called through proxy, raising the call’s gas usage above 2300. Additionally, using higher than 2300 gas might be mandatory for some multisig wallets. Whenever the user either fails to implement the payable fallback function or cumulative gas cost of the function sequence invoked on a native token transfer exceeds 2300 gas consumption limit the native tokens sent end up undelivered and the corresponding user funds return functionality will fail each time. https://github.com/code-423n4/2022-10-blur/blob/main/contracts/BlurExchange.sol#L508

3 += COSTS MORE GAS THAN = + FOR STATE VARIABLES

https://github.com/code-423n4/2022-10-blur/blob/main/contracts/BlurExchange.sol#L208 https://github.com/code-423n4/2022-10-blur/blob/main/contracts/BlurExchange.sol#L479

4 ABI.ENCODE() IS LESS EFFICIENT THAN ABI.ENCODEPACKED()

https://github.com/code-423n4/2022-10-blur/blob/main/contracts/lib/EIP712.sol#L45 https://github.com/code-423n4/2022-10-blur/blob/main/contracts/lib/EIP712.sol#L61 https://github.com/code-423n4/2022-10-blur/blob/main/contracts/lib/EIP712.sol#L91 https://github.com/code-423n4/2022-10-blur/blob/main/contracts/lib/EIP712.sol#L132

5 Use != 0 instead of > 0 at the above mentioned codes. The variable is uint, so it will not be below 0 so it can just check != 0.

!= 0 costs less gas compared to > 0 for unsigned integers in require statements with the optimizer enabled https://github.com/code-423n4/2022-10-blur/blob/main/contracts/BlurExchange.sol#L557

6 REQUIRE()/REVERT() STRINGS LONGER THAN 32 BYTES COST EXTRA GAS

Each extra memory word of bytes past the original 32 incurs an MSTORE which costs 3 gas https://github.com/code-423n4/2022-10-blur/blob/main/contracts/BlurExchange.sol#L318 https://github.com/code-423n4/2022-10-blur/blob/main/contracts/BlurExchange.sol#L534

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

Gas Optimizations #785