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code-423n4 / 2022-09-artgobblers-findings

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Gas Optimizations #108

Closed code423n4 closed 2 years ago

code423n4 commented 2 years ago

Gas Optimizations

G-01: pre-increment ++i/--i costs less gas than post-increment i++/i--

Saves 6 gas per loop in a for loop

Total instances of this issue: 2

instance #1 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Pages.sol#L251

src/Pages.sol

251:            for (uint256 i = 0; i < numPages; i++) _mint(community, ++lastMintedPageId);

instance #2 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/GobblerReserve.sol#L37

src/utils/GobblerReserve.sol

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

G-02: ++i/i++ should be placed in unchecked blocks to save gas as it is impossible for them to overflow in for and while loops

Unchecked keyword is available in solidity version 0.8.0 or higher and can be applied to iterator variables to save gas. Saves more than 30 gas per loop.

Total instances of this issue: 2

instance #1 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L186

src/utils/token/GobblersERC721.sol

186:            for (uint256 i = 0; i < amount; ++i) {

instance #2 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Pages.sol#L251

src/Pages.sol

251:            for (uint256 i = 0; i < numPages; i++) _mint(community, ++lastMintedPageId);

G-03: Length of the array (<array>.length) need not be looked up in every iteration of a for-loop

Reading array length at each iteration of the loop takes total 6 gas (3 for mload and 3 to place memory_offset) in the stack. Caching the array.length saves around 3 gas per iteration.

Total instances of this issue: 2

instance #1 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC1155B.sol#L114

src/utils/token/GobblersERC1155B.sol

114:            for (uint256 i = 0; i < owners.length; ++i) {

instance #2 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/GobblerReserve.sol#L37

src/utils/GobblerReserve.sol

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

G-04: x += y costs more gas than x = x + y for state variables

Total instances of this issue: 9

instance #1 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L439

src/ArtGobblers.sol

439:                burnedMultipleTotal += getGobblerData[id].emissionMultiple;

instance #2 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L662

src/ArtGobblers.sol

662:                getUserData[currentIdOwner].emissionMultiple += uint32(newCurrentIdMultiple);

instance #3 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L844

src/ArtGobblers.sol

844:            uint256 newNumMintedForReserves = numMintedForReserves += (numGobblersEach << 1);

instance #4 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L912

src/ArtGobblers.sol

912:            getUserData[to].emissionMultiple += emissionMultiple;

instance #5 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L913

src/ArtGobblers.sol

913:            getUserData[to].gobblersOwned += 1;

instance #6 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/lib/solmate/src/utils/SignedWadMath.sol#L203

lib/solmate/src/utils/SignedWadMath.sol

203:        r += 16597577552685614221487285958193947469193820559219878177908093499208371 * k;

instance #7 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/lib/solmate/src/utils/SignedWadMath.sol#L205

lib/solmate/src/utils/SignedWadMath.sol

205:        r += 600920179829731861736702779321621459595472258049074101567377883020018308;

instance #8 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L184

src/utils/token/GobblersERC721.sol

184:            getUserData[to].gobblersOwned += uint32(amount);

instance #9 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Pages.sol#L244

src/Pages.sol

244:            uint256 newNumMintedForCommunity = numMintedForCommunity += uint128(numPages);

G-05: Multiplication or Division by two should use bit shifting

<x> * 2 is the same as <x> >> 1 and <x> / 2 is the same as <x> >> 1. MUL and DIV opcodes cost 2 gas more than SHL and SHR.

Total instances of this issue: 2

instance #1 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L449

src/ArtGobblers.sol

449:            getGobblerData[gobblerId].emissionMultiple = uint32(burnedMultipleTotal * 2);

instance #2 Permalink: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L461-L463

src/ArtGobblers.sol

461:            legendaryGobblerAuctionData.startPrice = uint120(
462:                cost <= LEGENDARY_GOBBLER_INITIAL_START_PRICE / 2 ? LEGENDARY_GOBBLER_INITIAL_START_PRICE : cost * 2
463:            );

G-06: Adding payable to functions which are only meant to be called by specific actors like onlyOwner will save gas cost

Marking functions payable removes additional checks for whether a payment was provided, hence reducing gas cost

Total instances of this issue: 3

instance #1 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L560

src/ArtGobblers.sol

560:    function upgradeRandProvider(RandProvider newRandProvider) external onlyOwner {

instance #2 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/lib/solmate/src/auth/Owned.sol#L39

lib/solmate/src/auth/Owned.sol

39:    function setOwner(address newOwner) public virtual onlyOwner {

instance #3 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/GobblerReserve.sol#L34

src/utils/GobblerReserve.sol

34:    function withdraw(address to, uint256[] calldata ids) external onlyOwner {

G-07: No need to initialize non-constant/non-immutable variables to zero

Since the default value is already zero, overwriting is not required. Saves 8 gas per instance.

Total instances of this issue: 7

instance #1 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L432

src/ArtGobblers.sol

432:            for (uint256 i = 0; i < cost; ++i) {

instance #2 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L592

src/ArtGobblers.sol

592:            for (uint256 i = 0; i < numGobblers; ++i) {

instance #3 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC1155B.sol#L114

src/utils/token/GobblersERC1155B.sol

114:            for (uint256 i = 0; i < owners.length; ++i) {

instance #4 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC1155B.sol#L173

src/utils/token/GobblersERC1155B.sol

173:            for (uint256 i = 0; i < amount; ++i) {

instance #5 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L186

src/utils/token/GobblersERC721.sol

186:            for (uint256 i = 0; i < amount; ++i) {

instance #6 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Pages.sol#L251

src/Pages.sol

251:            for (uint256 i = 0; i < numPages; i++) _mint(community, ++lastMintedPageId);

instance #7 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/GobblerReserve.sol#L37

src/utils/GobblerReserve.sol

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

G-08: Using uints/ints smaller than 256 bits increases overhead

Gas usage becomes higher with uint/int smaller than 256 bits because EVM operates on 32 bytes and uses additional operations to reduce the size from 32 bytes to the target size.

Total instances of this issue: 18

instance #1 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L159

src/ArtGobblers.sol

159:    uint128 public numMintedFromGoo;

instance #2 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L167

src/ArtGobblers.sol

167:    uint128 public currentNonLegendaryId;

instance #3 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L189

src/ArtGobblers.sol

189:        uint128 startPrice;

instance #4 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L191

src/ArtGobblers.sol

191:        uint128 numSold;

instance #5 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L204

src/ArtGobblers.sol

204:        uint64 randomSeed;

instance #6 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L206

src/ArtGobblers.sol

206:        uint64 nextRevealTimestamp;

instance #7 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L208

src/ArtGobblers.sol

208:        uint56 lastRevealedId;

instance #8 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/ArtGobblers.sol#L210

src/ArtGobblers.sol

210:        uint56 toBeRevealed;

instance #9 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC1155B.sol#L48

src/utils/token/GobblersERC1155B.sol

48:        uint64 idx;

instance #10 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC1155B.sol#L50

src/utils/token/GobblersERC1155B.sol

50:        uint32 emissionMultiple;

instance #11 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L38

src/utils/token/GobblersERC721.sol

38:        uint64 idx;

instance #12 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L40

src/utils/token/GobblersERC721.sol

40:        uint32 emissionMultiple;

instance #13 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L49

src/utils/token/GobblersERC721.sol

49:        uint32 gobblersOwned;

instance #14 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L51

src/utils/token/GobblersERC721.sol

51:        uint32 emissionMultiple;

instance #15 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L53

src/utils/token/GobblersERC721.sol

53:        uint128 lastBalance;

instance #16 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/utils/token/GobblersERC721.sol#L55

src/utils/token/GobblersERC721.sol

55:        uint64 lastTimestamp;

instance #17 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Pages.sol#L107

src/Pages.sol

107:    uint128 public currentId;

instance #18 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/src/Pages.sol#L114

src/Pages.sol

114:    uint128 public numMintedForCommunity;

G-09: Using != 0 costs less gas than > 0 in a require() statement

Saves 6 gas per instance for solidity version less than 0.8.12.

Total instances of this issue: 1

instance #1 Link: https://github.com/code-423n4/2022-09-artgobblers/blob/main/lib/solmate/src/utils/SignedWadMath.sol#L142

lib/solmate/src/utils/SignedWadMath.sol

142:        require(x > 0, "UNDEFINED");
GalloDaSballo commented 2 years ago

100 gas at most