Numoen contest - ReyAdmirado's results

1. <x> += <y> costs more gas than <x> = <x> + <y> for state variables

Using the addition operator instead of plus-equals saves gas

• Lendgine.sol#L91
• Lendgine.sol#L257
• Lendgine.sol#L114
• Lendgine.sol#L176

2. not using the named return variables when a function returns, wastes deployment gas

• JumpRate.sol#L13
• JumpRate.sol#L32
• JumpRate.sol#L40

3. Avoid a SLOAD optimistically

There is a chance that the first part will be true so the second part doesn’t need to be checked, so it is better to use the part that we have instead of the part that needs to be called.

swapping these lines will have a chance to stop the getLendgine[token0][token1][token0Exp][token1Exp][upperBound] SLOAD

• Factory.sol#L76-L77

4. use a more recent version of solidity

Use a strict solidity version

Use a solidity version of at least 0.8.2 to get compiler automatic inlining Use a solidity version of at least 0.8.3 to get better struct packing and cheaper multiple storage reads Use a solidity version of at least 0.8.4 to get custom errors, which are cheaper at deployment than revert()/require() strings Use a solidity version of at least 0.8.10 to have external calls skip contract existence checks if the external call has a return value Use a solidity version of at least 0.8.12 to get string.concat() to be used instead of abi.encodePacked(<str>,<str>) Use a solidity version of at least 0.8.13 to get the ability to use using for with a list of free functions Use a solidity version of at least 0.8.15 because the conditions necessary for inlining are relaxed. Benchmarks show that the change significantly decreases the bytecode size (which impacts the deployment cost) while the effect on the runtime gas usage is smaller. Use a solidity version of at least 0.8.17 to get prevention of the incorrect removal of storage writes before calls to Yul functions that conditionally terminate the external EVM call; Simplify the starting offset of zero-length operations to zero. More efficient overflow checks for multiplication.

5. Ternary over if ... else

Using ternary operator instead of the if else statement saves gas.

• JumpRate.sol#L16-L22

• LiquidityManager.sol#L147-L153

• LendgineRouter.sol#L205-L211

• Position.sol#L56-L60

6. use existing cached version of state var

totalPositionSize is already cached inside the _totalPositionSize state var, use the cached version to save 100 gas

• Lendgine.sol#L142

7. Non-strict inequalities are cheaper than strict ones

In the EVM, there is no opcode for non-strict inequalities (>=, <=) and two operations are performed (> + = or < + =). consider replacing >= with the strict counterpart > and add - 1 to the second side

• Pair.sol#L66

8. pre calculate parts of the code

some parts of the code are doing operations on constants (e.g. (constantA * constantB) / 1e18) which will always give us the same answer so there is no need to calculate them every time the function is being used.

just calculate the answer to this part of the code and use it where it should be used.

(kink * multiplier) / 1e18; always gives the same answer. (with this method the normalRate stack variable wouldnt need to be made which also saves gas)

• JumpRate.sol#L19

9. consider making a standard size for variables

token0Exp and token1Exp are getting different declarations in some of the contracts. as they are small numbers they can be put into a small uint and be in the same slot with token0 and token1 which are 20 bytes. as they are used together in the same places it will both save gas for slotting and reads and writes. (Each slot saved can avoid an extra Gsset (20000 gas) for the first setting of the struct and subsequent reads as well as writes have smaller gas savings)

saves two slots here each

• LiquidityManager.sol#L92-101
• LiquidityManager.sol#L120-132
• LiquidityManager.sol#L187-L198

saves two slots here each

• LendgineRouter.sol#L74-L84
• LendgineRouter.sol#L126-L139
• LendgineRouter.sol#L175-187
• LendgineRouter.sol#L240-L254

saves one slot here

• Factory.sol#L47-L53