Y2k Finance contest - SnowMan's results

1. Using storage instead of memory for struct/array saves gas

When fetching data from a storage location, assigning the data to a memory variable causes all fields of the struct/array to be read from storage, which incurs a Gcoldsload (2100 gas) for each field of the struct/array. If the fields are read from the new memory variable, they incur an additional MLOAD rather than a cheap stack read. Instead of declearing the variable with the memory keyword, declaring the variable with the storage keyword and caching any fields that need to be re-read in stack variables, will be much cheaper, only incuring the Gcoldsload for the fields actually read. The only time it makes sense to read the whole struct/array into a memory variable, is if the full struct/array is being returned by the function, is being passed to a function that requires memory, or if the array/struct is being read from another memory array/struct

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L171 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L227 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L234 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L263

2. Storage variables should be declared immutable when possible

If a storage variable is assigned only in the constructor, it should be declared as immutable. This would help to reduce gas costs as calls to immutable variables are much cheaper than regular state variables.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L20-L21 https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/oracles/PegOracle.sol#L10-L11

3. Using cache to contain "array.length"

-storage arrays incur a Gwarmaccess (100 gas) -memory arrays use MLOAD (3 gas) -calldata arrays use CALLDATALOAD (3 gas)

Caching the length of the array changes it to a DUP<N> (3 gas), and gets rid of the extra DUP<N> needed to store the stack offset:

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L86 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L200 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L431

4. Multiple accesses of a mapping/array should use a local variable cache

The instances below point to the second+ access of a value inside a mapping/array, within a function. Caching a mapping's value in a local storage variable when the value is accessed multiple times, saves ~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. Caching an array's struct avoids recalculating the array offsets into memory.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L314 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L320 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L321 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L324 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L400 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L401 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L407 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L408 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L419 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L420 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L221 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L222 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L372 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/RewardsFactory.sol#L119 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L64 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L65

5. It costs more gas to initialize variables with their default value than letting the default value be applied

If a variable is not set/initialized, it is assumed to have the default value (0 for uint, false for bool, address(0) for address). Explicitly initializing it with its default value is an anti-pattern and wastes gas.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L90 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L443

6. For-Loops: Index increments can be left unchecked

From Solidity v0.8 onwards, all arithmetic operations come with implicit overflow and underflow checks. In for-loops, as it is impossible for the index to overflow, it can be left unchecked to save gas every iteration.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L443

7. Arithmetics: ++i costs less gas compared to i++ or i += 1

++i costs less gas compared to i++ or i += 1 for unsigned integers, as pre-increment is cheaper (about 5 gas per iteration). This statement is true even with the optimizer enabled.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L443 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L195

8. Arithmetics: Unchecking arithmetic operations that cannot underflow/overflow

From Solidity v0.8 onwards, all arithmetic operations come with implicit overflow and underflow checks. In some instances, an overflow/underflow is impossible, such as:

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L195 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L448 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L445 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L227 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L283

9. Visibility: public functions can be set to external

Calls to external functions are cheaper than public functions. Thus, if a function is not used internally in any contract, it should be set to external to save gas and improve code readability.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L148 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L198 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L261 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L85 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L137 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L143 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L159 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L175 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L189 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L205 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L221 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L237 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L244 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L251 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L263 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L260 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L277 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L287 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L295 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L307 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L336 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L350 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L360 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L378 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L430 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L438 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L186 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L248 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L295 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L308 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L327 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L345 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L366 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L385 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/oracles/PegOracle.sol#L46 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/oracles/PegOracle.sol#L89 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/oracles/PegOracle.sol#L112

10. ">=" and "<=" costs less gas than ">" and "<"

This action saves 3 gas - https://gist.github.com/IllIllI000/3dc79d25acccfa16dee4e83ffdc6ffde Add one to the amount and use ">=" instead of ">". (if it's ">") Subtract one out of the amount and use "<=" instead of "<". (if it's "<")

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L187 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L311 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L119 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/oracles/PegOracle.sol#L98 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/oracles/PegOracle.sol#L121

11. Functions guaranteed to revert when called by normal users can be marked payable

If a function modifier such as onlyPartyDao is used, the function will revert if a normal user tries to pay the function. Marking the function as payable will lower the gas cost for legitimate callers because the compiler will not include checks for whether a payment was provided.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L178 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L248 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L295 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L308 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L327 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L345 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L366

12. Cache storage values in memory to minimize sloads.

The code can be optimized by minimising the number of SLOADs. SLOADs are expensive 100 gas compared to MLOADs/MSTOREs(3gas) Storage value should get cached in memory

marketIndex should be cached: https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L195 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L219 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L234

periodFinish should be cached: https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L189 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L192 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L208

rewardRate should be cached: https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L190 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L193 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L194 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L203

rewardsDuration should be cached: https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L190 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L194 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L203 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L208

13. Not using the named return variables, when a function returns, wastes deployment gas.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L261 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L260 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L438 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L178 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/VaultFactory.sol#L385 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/RewardsFactory.sol#L83 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/RewardsFactory.sol#L145 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/oracles/PegOracle.sol#L46 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/oracles/PegOracle.sol#L89 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/oracles/PegOracle.sol#L112

14. Visibility: Consider declaring constants as non-public to save gas

If a constant is not used outside of its contract, declaring it as private or internal instead of public can save gas.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L16

15. Errors: Use custom errors instead of revert strings

Since Solidity v0.8.4, custom errors should be used instead of revert strings due to:

-Cheaper deployment cost -Lower runtime cost upon revert

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L91 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L116 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L165 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L187 https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/oracles/PegOracle.sol#L23-L31 https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/oracles/PegOracle.sol#L98-L103 https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/oracles/PegOracle.sol#L121-L126 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L96 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L119 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L202 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L217 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L226

16. Visibility: Consider declaring constants as non-public to save gas

If a constant is not used outside of its contract, declaring it as private or internal instead of public can save gas.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L16

17. Errors: Reduce the length of error messages (long revert strings)

Shortening revert strings to fit in 32 bytes will decrease deployment time gas and will decrease runtime gas when the revert condition is met. Revert strings that are longer than 32 bytes require at least one additional mstore, along with additional overhead for computing memory offset, etc.

In these instances, consider shortening the revert strings to fit within 32 bytes: https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L116 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L226 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L202 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/rewards/StakingRewards.sol#L217 https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/oracles/PegOracle.sol#L23-L30 https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/oracles/PegOracle.sol#L98-L103 https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/oracles/PegOracle.sol#L121-L126

18. Using bools for storage incurs overhead

    // Booleans are more expensive than uint256 or any type that takes up a full // word because each write operation emits an extra SLOAD to first read the // slot's contents, replace the bits taken up by the boolean, and then write // back. This is the compiler's defense against contract upgrades and // pointer aliasing, and it cannot be disabled.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L52 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L54

19. internal functions only called once can be inlined to save gas

Not inlining costs 20 to 40 gas because of two extra JUMP instructions and additional stack operations needed for function calls.

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L276 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol#L282

20. Don't compare boolean expressions to boolean literals

if (<x> == true) => if (<x>), if (<x> == false) => if (!<x>)

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L93 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Controller.sol#L211 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L96 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L217 https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L314

21. "OR" conditions cost less gas than their equivalent "AND" conditions

Remember that the equivalent of (a && b) is !(!a || !b)

https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L96 https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/Vault.sol#L215-L217

Example for - https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/Vault.sol#L96 -96: if((block.timestamp < id) && idDepegged[id] == false) +96: if(!((block.timestamp > id) || idDepegged[id] != false))

Example for - https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/Vault.sol#L215-L217 -215: if(msg.sender != owner && isApprovedForAll(owner, receiver) == false) +215: if(!(msg.sender == owner || isApprovedForAll(owner, receiver) != false))