Gas Optimizations

[code423n4]

Hey guy, here are the Gas Optimizations:

-> X = X + Y IS CHEAPER THAN X += Y (Same for X = X - Y is cheaper than X -= Y)

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=idx%20%3C%20shortest%3B-,idx%20%2B%3D%2032),-%7B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=%7D-,selfptr%20%2B%3D%2032%3B,-otherptr%20%2B%3D%2032

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=%2B%3D%2032%3B-,otherptr%20%2B%3D%2032%3B,-%7D

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=%7D-,dest%20%2B%3D%2032%3B,-src%20%2B%3D%2032

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=%2B%3D%2032%3B-,src%20%2B%3D%2032%3B,-%7D

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/RRUtils.sol#:~:text=idx-,%2B%3D,-labelLen%20%2B%201

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/RRUtils.sol#:~:text=counts-,%2D%3D,-1%3B

-> COMPARISON OPERATORS Problem

In the EVM, there is no opcode for >= or <=. When using greater than or equal, two operations are performed: > and =.
Using strict comparison operators hence saves gas

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=return%20self.length-,%3E%3D,-offset%20%2B%20other

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=for%20(%3B%20len-,%3E%3D,-32%3B%20len%20%2D%3D

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=require(char-,%3E%3D,-0x30%20%26%26%20char

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=offset%20%2B%20len-,%3C%3D%20self.length)%3B,-assembly%20%7B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=idx%20%2B%202-,%3C%3D,-self.length

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=idx%20%2B%204-,%3C%3D,-self.length

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=idx%20%2B%2032-,%3C%3D,-self.length

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=idx%20%2B%2020-,%3C%3D,-self.length

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=require(len-,%3C%3D,-32)%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=idx%20%2B%20len-,%3C%3D,-self.length

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=offset%20%2B%20len-,%3C%3D%20self.length)%3B,-bytes%20memory%20ret

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=require(len-,%3C%3D,-52)%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=0x30%20%26%26%20char-,%3C%3D,-0x7A)%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=require(decoded-,%3C%3D,-0x20)%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=32%3B%20len-,%2D%3D,-32)%20%7B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=bitlen-,%2D%3D,-2%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=bitlen-,%2D%3D,-4%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=bitlen-,%2D%3D,-1%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=bitlen-,%2D%3D,-3%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/RRUtils.sol#:~:text=return%20iter.offset-,%3E%3D,-iter.data.

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/RRUtils.sol#:~:text=(iter.offset-,%3E%3D,-iter.data.

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/RRUtils.sol#:~:text=int32(i2)-,%3E%3D,-0%3B

-> It costs more gas to initialize a varaible to 0 than to let the default of zero be applied

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=for(-,uint%20i%20%3D%200%3B,-i%20%3C%20len

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=for%20(-,uint%20idx%20%3D%200%3B,-idx%20%3C%20shortest

-> ++i costs less gas compared to i++ or i += 1 (Also --i costs less gas compared to i--- or i -= 1)

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=i%20%3C%20len%3B-,i%2B%2B),-%7B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/DNSSECImpl.sol#:~:text=for(-,uint%20i%20%3D%200%3B,-i%20%3C%20input

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/DNSSECImpl.sol#:~:text=input.length%3B-,i%2B%2B),-%7B

->SPLITTING REQUIRE() STATEMENTS THAT USE && SAVES GAS

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=require(char%20%3E%3D%200x30%20%26%26%20char%20%3C%3D%200x7A)%3B

-> Usage of Units/Uints smaller than 32Byte (256Bits) incurs overhead

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=decoded%20%3D-,uint8,-(base32HexTable%5Buint

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/BytesUtils.sol#:~:text=base32HexTable%5Buint(-,uint8,-(char))%20%2D

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/DNSSECImpl.sol#:~:text=for%20*%3B-,uint16,-constant%20DNSCLASS_IN%20%3D

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/DNSSECImpl.sol#:~:text=%3D%201%3B-,uint16,-constant%20DNSTYPE_DS%20%3D

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/DNSSECImpl.sol#:~:text=%3D%2043%3B-,uint16,-constant%20DNSTYPE_DNSKEY%20%3D

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/DNSSECImpl.sol#:~:text=mapping%20(-,uint8,-%3D%3E%20Algorithm)

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/DNSSECImpl.sol#:~:text=mapping%20(-,uint8,-%3D%3E%20Digest)

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/RRUtils.sol#:~:text=struct%20SignedSet%20%7B-,uint16%20typeCovered%3B,-uint8%20algorithm%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/RRUtils.sol#:~:text=uint16%20typeCovered%3B-,uint8%20algorithm%3B,-uint8%20labels%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/RRUtils.sol#:~:text=uint8%20algorithm%3B-,uint8%20labels%3B,-uint32%20ttl%3B

https://github.com/code-423n4/2022-07-ens/blob/main/contracts/dnssec-oracle/RRUtils.sol#:~:text=uint32%20inception%3B-,uint16%20keytag%3B,-bytes%20signerName%3B