Gas Optimizations

[code423n4]

Solidity 6.12 you need to use safemath library and in newer version of solidity the compiler checks overflow/underflow which saves gas
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/CollateralAdapter.sol#L2
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L2
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/LidoVault.sol#L2

Make onlyadmin and initializer functions payable because it doesn't check msg.value == 0 because it saves gas
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/CollateralAdapter.sol#L37
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/CollateralAdapter.sol#L45
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L49
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L114
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L68
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L183
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/LidoVault.sol#L32
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L63
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L67
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L76
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L96
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L124

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Use revert instead of require statement and if you upgrade to 0.8.0 and up then gas is lower
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L51
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L88
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L124
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L173
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L237
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L34
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L40
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L199
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/LidoVault.sol#L95
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/LidoVault.sol#L106
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/LidoVault.sol#L158
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L102
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L218

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https://docs.soliditylang.org/en/v0.8.13/abi-spec.html#:~:text=Through%20abi.,place%20and%20without%20the%20length. abi.encoded packed, packs the string to ? mayabe use bytes to save gas bec it's less than 32 bytes
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L60
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L59
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We can make this != because _vault fee cant be less than zero,uint256 internal _vaultFee
This will save gas because it only needs to check for anything less than zero
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L95
///@Audit change >0 to != because its uint and is always greater or equal to zero
require(yieldStAsset > 0, Errors.VT_PROCESS_YIELD_INVALID);

https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/LidoVault.sol#L40

Waste of variables in memory because we can just put it into function instead
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L97
yieldAmount=yieldAmount.sub(_processTreasury(_asset, yieldAmount)); this instead

you can get rid of baseRewardPool and just put the function inside function bec view function does not cast gas its just reading of blockchain but the variable is mstore
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L117
saves 6 gas mstore and mload just combine and save gas _transferYield(IRewards(IConvexBaseRewardPool(getBaseRewardPool()).extraRewards(i)).rewardToken());
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L142
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already returns uint8 no need for a extra variable
10**IERC20Detailed(internalAssetToken).decimals()

https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L159
address baseRewardPool = getBaseRewardPool();
IConvexBaseRewardPool(baseRewardPool).withdrawAndUnwrap(_amount, true);
We can remove baseRewardPool and just put into the function
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L203
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///@Audit save gas by removing decimal varible bec it already returns a uint8
// uint256 decimal = IERC20Detailed(_asset).decimals();

  _amount = _amountToWithdraw.mul(this.pricePerShare()).div(10**IERC20Detailed(_asset).decimals());

Remove decimal variable https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L136
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uint256 yieldStAsset = _getYieldAmount(_stAsset);
Waste of yieldstasset you can just return the function and put it into the line after
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L196
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//uint256 treasuryStETH = _processTreasury(yieldStETH);
yieldStETH = yieldStETH.sub(_processTreasury(yieldStETH));
You can just remove treasury stEth and save mstore and mload
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a waste of variable you can just use _amount or msg.value in the field
assetAmount = msg.value;
This it a waste just use msg.value and with the assetAmount you can get rid off because you can just use _amount
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Instead of _amount just put it into the function
// uint256 _amount = IERC20Detailed(asset).balanceOf(address(this));
_convertAssetToExchangeToken(asset, IERC20Detailed(asset).balanceOf(address(this)));

https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L132
uint256 _amount = _convertToStableCoin(assetYields[i].asset, assetYields[i].amount);
// 3. deposit Yield to pool for suppliers
_depositYield(assetYields[i].asset, _amount);

Take out _amount and just put that into _depositYield
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L145

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++i costs less gas compared to i++ or i += 1
++i costs less gas compared to i++ or i += 1 for unsigned integer, as pre-increment is cheaper (about 5 gas per iteration). This statement is true even with the optimizer enabled. i++ increments i and returns the initial value of i. Which means:
uint i = 1; i++; // == 1 but i == 2
But ++i returns the actual incremented value:
uint i = 1; ++i; // == 2 and i == 2 too, so no need for a temporary variable In the first case, the compiler has to create a temporary variable (when used) for returning 1 instead of 2

https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/ConvexCurveLPVault.sol#L137
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L238
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L127
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L141

make indexed for 3 fields if there are more than 3 fields
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L27
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L29
you can add 256-160 uint96 to this struct if you want without any gas cost
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/GeneralVault.sol#L49
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L32

you can add 96 uint for free bec mapping starts a new slot and address takes up 160 bits out of 256 bits
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L45
make it _assetList array in memory bec of mappings isn't to bad for gas but its still a lot of gas of storage and its still in a function in a for loop, find way to not use it for a memory variable at least
address asset = _assetsList[_offset + i];
https://github.com/code-423n4/2022-05-sturdy/blob/6cc44472f6321d0be6844d6fe7fbd7b78d7602a9/smart-contracts/YieldManager.sol#L129

make it default variable of zero and not initialized the variable to save gas becuase this var is only assigned after and its assignment now is doesn't need it bec it's already a variable in use
Also because _totalYieldAmount is used in the math calculation only.
uint256 extraYieldAmount = _totalYieldAmount;