Gas Optimizations

[code423n4]

USDC ENS

Author: Rolezn

=================
Gas Optimizations

(1) Constants can be set to uint8 for gas optimizations

uint16 constant DNSCLASS_IN =1;
uint16 constant DNSTYPE_DS =43;
uint16 constant DNSTYPE_DNSKEY =48;

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/DNSSECImpl.sol#L21-L24

(2) ++i costs less gas than i++, especially when it’s used in for-loops (--i/i-- too)

Saves gas per loop

Proof Of Concept

for(uint i = 0; i < len; i++) {

From https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#L266

for(uint i = 0; i < input.length; i++) {

From https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/DNSSECImpl.sol#L93

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

From https://github.com/code-423n4/2022-07-ens/blob/main/contracts/ethregistrar/ETHRegistrarController.sol#L256

(3) Using private rather than public for constants, saves gas

If needed, the value can be read from the verified contract source code. Savings are due to the compiler not having to create non-payable getter functions for deployment calldata, and not adding another entry to the method ID table

Proof Of Concept

uint256 public constant MIN_REGISTRATION_DURATION = 28 days;

From https://github.com/code-423n4/2022-07-ens/blob/main/contracts/ethregistrar/ETHRegistrarController.sol#L21

(4) It costs more gas to initialize variables to zero than to let the default of zero be applied

Proof Of Concept

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

From https://github.com/code-423n4/2022-07-ens/blob/main/contracts/ethregistrar/ETHRegistrarController.sol#L256

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

From https://github.com/code-423n4/2022-07-ens/blob/main/contracts/wrapper/ERC1155Fuse.sol#L92

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

From https://github.com/code-423n4/2022-07-ens/blob/main/contracts/wrapper/ERC1155Fuse.sol#L92