Timeswap contest - atharvasama's results

Gas Optimizations list

Gas Optimizations

[G-01] x += y costs more gas than x = x + y. x -= y costs more gas than x = x - y

Using the addition/subtraction operators instead of plus-equals/minus-equals saves gas.

packages\v2-library\src\FullMath.sol:

163:             productA1 += (quotient1 * divisor);

packages\v2-option\src\structs\Option.sol:

62              option.long0[msg.sender] -= amount;
63:             option.long0[to] += amount;
65:             option.long1[to] += amount;
66              option.long1[msg.sender] -= amount;
68              option.short[msg.sender] -= amount;
69:             option.short[to] += amount;
103:             option.totalLong0 += token0AndLong0Amount;
104:             option.long0[long0To] += token0AndLong0Amount;
108:             option.totalLong1 += token1AndLong1Amount;
109:             option.long1[long1To] += token1AndLong1Amount;
112:         option.short[shortTo] += shortAmount;
141:         option.totalLong0 -= token0AndLong0Amount;
142:         option.totalLong1 -= token1AndLong1Amount;
173              option.totalLong0 -= token0AndLong0Amount;
174:             option.totalLong1 += token1AndLong1Amount;
175:             option.long1[longTo] += token1AndLong1Amount;
177              option.totalLong1 -= token1AndLong1Amount;
178:             option.totalLong0 += token0AndLong0Amount;
179:             option.long0[longTo] += token0AndLong0Amount;
208:         option.totalLong0 -= token0Amount;
209:         option.totalLong1 -= token1Amount;

packages\v2-pool\src\libraries\ConstantProduct.sol:

149:         if (isAdd) longAmount -= fees;
150:         else shortAmount -= fees;
180:             shortAmount -= fees;
212:             longAmount -= fees;
244:         amount -= fees;
295:             denominator2 += longAmount;

packages\v2-pool\src\structs\LiquidityPosition.sol:

55:             liquidityPosition.long0Fees += FeeCalculation.getFees(liquidity, liquidityPosition.long0FeeGrowth, long0FeeGrowth);
56:             liquidityPosition.long1Fees += FeeCalculation.getFees(liquidity, liquidityPosition.long1FeeGrowth, long1FeeGrowth);
57:             liquidityPosition.shortFees += FeeCalculation.getFees(liquidity, liquidityPosition.shortFeeGrowth, shortFeeGrowth);
66:         liquidityPosition.liquidity += liquidityAmount;
70:         liquidityPosition.long0Fees += long0Fees;
71:         liquidityPosition.long1Fees += long1Fees;
72:         liquidityPosition.shortFees += shortFees;
76:         liquidityPosition.liquidity -= liquidityAmount;
80:         liquidityPosition.long0Fees -= long0Fees;
81:         liquidityPosition.long1Fees -= long1Fees;
82:         liquidityPosition.shortFees -= shortFees;

packages\v2-pool\src\structs\Pool.sol:

361:         if (long0Amount != 0) pool.long0Balance += long0Amount;
362:         if (long1Amount != 0) pool.long1Balance += long1Amount;
365:         pool.liquidity += liquidityAmount; 
537:         if (long0Amount != 0) pool.long0Balance += long0Amount;
538:         if (long1Amount != 0) pool.long1Balance += long1Amount;
695:             pool.long0Balance += long0Amount;
722:             pool.long1Balance += long1Amount;
452:         if (long0Amount != 0) pool.long0Balance -= long0Amount;
453:         if (long1Amount != 0) pool.long1Balance -= long1Amount;
455:         pool.liquidity -= liquidityAmount;
636:                 pool.long0Balance -= (long0Amount + long0Fees);
650:                 pool.long1Balance -= (long1Amount + long1Fees);
677:                 pool.long1Balance -= (long1Amount + longFees);
689:                     pool.long1Balance -= (long1Amount + longFees);
710:                     pool.long0Balance -= (long0Amount + longFees);
719:                 pool.long0Balance -= (long0Amount + longFees);

packages\v2-token\src\base\ERC1155Enumerable.sol:

61:             _idTotalSupply[id] += amount;
95:             _idTotalSupply[id] -= amount;
117:         _currentIndex[to] += 1;

packages\v2-token\src\structs\FeesPosition.sol:

31:             feesPosition.long0Fees += FeeCalculation.getFees(liquidity, feesPosition.long0FeeGrowth, long0FeeGrowth);
32:             feesPosition.long1Fees += FeeCalculation.getFees(liquidity, feesPosition.long1FeeGrowth, long1FeeGrowth);
33:             feesPosition.shortFees += FeeCalculation.getFees(liquidity, feesPosition.shortFeeGrowth, shortFeeGrowth);
53:         feesPosition.long0Fees += long0Fees;
54:         feesPosition.long1Fees += long1Fees;
55:         feesPosition.shortFees += shortFees;
59:         feesPosition.long0Fees -= long0Fees;
60:         feesPosition.long1Fees -= long1Fees;
61:         feesPosition.shortFees -= shortFees;

packages\v2-option\src\TimeswapV2Option.sol:

190:         option.long0[msg.sender] -= token0AndLong0Amount;
191:         option.long1[msg.sender] -= token1AndLong1Amount;
192:         option.short[msg.sender] -= shortAmount;
237:         if (param.isLong0ToLong1) option.long0[msg.sender] -= token0AndLong0Amount;
238:         else option.long1[msg.sender] -= token1AndLong1Amount;
277:         option.short[msg.sender] -= shortAmount;

[G-02] Can declare the variable outside the loop to save gas

Declaring the loop variable outside the loop saves gas.

packages\v2-option\src\structs\Process.sol:

34:         for (uint256 i; i < processing.length; ) {

packages\v2-token\src\TimeswapV2LiquidityToken.sol:

227:         for (uint256 i; i < ids.length; ) {

packages\v2-token\src\base\ERC1155Enumerable.sol:

48:         for (uint256 i; i < ids.length; ) {
82:         for (uint256 i; i < ids.length; ) {

[G-03] Using local arguments instead of state variable saves gas

Using the local arguments of the function while emitting an event instead of the state variable saves roughly 122 gas per emit.

packages\v2-pool\src\base\OwnableTwoSteps.sol

29:         pendingOwner = chosenPendingOwner;
30: 
31:         emit SetOwner(pendingOwner);

can be refactored to

29:         pendingOwner = chosenPendingOwner;
30: 
31:         emit SetOwner(chosenPendingOwner);

[G-04] Expression can be unchecked when overflow is not possible

Using unchecked for an expression reduces the amount of opcodes required to check for overflow/underflow hence saving gas.

packages\v2-library\src\Math.sol

48:     function div(uint256 dividend, uint256 divisor, bool roundUp) internal pure returns (uint256 quotient) {
49:         quotient = dividend / divisor;
50: 
51:         if (roundUp && dividend % divisor != 0) quotient++;
52:     }

59:     function shr(uint256 dividend, uint8 divisorBit, bool roundUp) internal pure returns (uint256 quotient) {
60:         quotient = dividend >> divisorBit;
61: 
62:         if (roundUp && dividend % (1 << divisorBit) != 0) quotient++;
63:     }

81:         if (roundUp && value % result != 0) result++;

Dividing by 0 results in a revert. Since dividing any divisor by the dividend results in a quotient that is less than or equal to the dividend, it can be safely unchecked to save gas.

[G-05] Avoid contract existence checks by using low level calls

Prior to 0.8.10 the compiler inserted extra code, including EXTCODESIZE (100 gas), to check for contract existence for external function calls. In more recent solidity versions, the compiler will not insert these checks if the external call has a return value. Similar behavior can be achieved in earlier versions by using low-level calls, since low level calls never check for contract existence

packages\v2-token\src\TimeswapV2LiquidityToken.sol:

70      function transferTokenPositionFrom(address from, address to, TimeswapV2LiquidityTokenPosition calldata timeswapV2LiquidityTokenPosition, uint160 liquidityAmount) external {
71:         safeTransferFrom(from, to, _timeswapV2LiquidityTokenPositionIds[timeswapV2LiquidityTokenPosition.toKey()], liquidityAmount, bytes(""));
72      }

packages\v2-token\src\TimeswapV2Token.sol:

71      function transferTokenPositionFrom(address from, address to, TimeswapV2TokenPosition calldata timeswapV2TokenPosition, uint256 amount) external override {
72:         safeTransferFrom(from, to, _timeswapV2TokenPositionIds[timeswapV2TokenPosition.toKey()], (amount), bytes(""));
73      }

[G-06] Multiple address/id mappings can be combined into a single mapping to a struct

If both fields are accessed in the same function, can save ~42 gas per access due to not having to recalculate the key’s keccak256 hash (Gkeccak256 - 30 gas) and that calculation’s associated stack operations. Depending on the circumstances and sizes of types, can avoid a Gsset per mapping combined.

File: packages\v2-token\src\base\ERC1155Enumerable.sol

14:     // Mapping from owner to list of owned token IDs
15:     mapping(address => mapping(uint256 => uint256)) private _ownedTokens; // An index of all tokens
16: 
17:     mapping(address => uint256) private _currentIndex; // the current index for an address
18: 
19:     // Mapping from token ID to index of the owner tokens list
20:     mapping(uint256 => uint256) private _ownedTokensIndex;
21: 
22:     mapping(uint256 => uint256) private _idTotalSupply;
23: 
24:     // Array with all token ids, used for enumeration
25:     uint256[] private _allTokens;
26: 
27:     // Mapping from token id to position in the allTokens array
28:     mapping(uint256 => uint256) private _allTokensIndex;

In this contract the address mappings could be combined into one struct and the id mappings into another struct. The values could be cached into the stack and used for simple reads when required.

[G-07] Length of bytes array can be cached outside require

Length of the dynamic bytes array can be cached outside the require statement to save a small amount of gas.

packages\v2-library\src\BytesLib.sol:

12      function slice(bytes memory _bytes, uint256 _start, uint256 _length) internal pure returns (bytes memory) {
13:         require(_length + 31 >= _length, "slice_overflow");
14:         require(_bytes.length >= _start + _length, "slice_outOfBounds");

[G-08] Public functions not called by contract can be changed to external to save some gas

Contracts are allowed to override their parents’ functions and change the visibility from external to public and can save gas by doing so.

packages\v2-token\src\base\ERC1155Enumerable.sol:

35      /// @inheritdoc IERC1155Enumerable
36:     function totalSupply() public view override returns (uint256) {
37          return _allTokens.length;