GAS-1: <X> * 2 costs more gas then <X> << 1
Description
Using bitwize operator instead of '*' or '/' saves gas.
Affected file
- LybraEUSDVaultBase.sol (Line: 159)
- LybraPeUSDVaultBase.sol (Line: 130)
GAS-2: Add unchecked{} for subtractions where the operands cannot underflow because of a previous require() or if statement
Description
require(a <= b); x = b - a => require(a <= b); unchecked { x = b - a }
if(a <= b); x = b - a => if(a <= b); unchecked { x = b - a }
This will stop the check for overflow and underflow so it will save gas.
Affected file
- LBR.sol (Line: 22)
- LybraPeUSDVaultBase.sol (Line: 200)
- LybraStETHVault.sol (Line: 75, 78)
- PeUSD.sol (Line: 14)
- PeUSDMainnetStableVision.sol (Line: 60)
- ProtocolRewardsPool.sol (Line: 201, 202, 203, 209, 211)
GAS-3: Caching global variables is more expensive than using the actual variable
Description
It’s cheaper to use global variable as compared to caching.
Affected file
- EUSDMiningIncentives.sol (Line: 240)
- LybraEUSDVaultBase.sol (Line: 297)
- LybraStETHVault.sol (Line: 43, 92)
- stakerewardV2pool.sol (Line: 143)
GAS-4: Do not calculate constants
Description
Due to how constant variables are implemented (replacements at compile-time), an expression assigned to a constant variable is recomputed each time that the variable is used, which wastes some gas.
Affected file
- GovernanceTimelock.sol (Line: 10, 11, 12, 13)
- LybraConfigurator.sol (Line: 76, 77, 78)
GAS-5: Internal functions not called by the contract should be removed to save deployment gas
Description
If the functions are required by an interface, the contract should inherit from that interface and use the override keyword.
Affected file
- LBR.sol (Line: 49, 56, 61, 70)
- LybraEUSDVaultBase.sol (Line: 307)
- LybraGovernance.sol (Line: 59, 66, 76, 98)
- LybraPeUSDVaultBase.sol (Line: 244)
- PeUSD.sol (Line: 31, 38, 43, 52)
- PeUSDMainnetStableVision.sol (Line: 184, 191, 196, 205)
- esLBR.sol (Line: 26)
GAS-6: Length calculated at each iteration in For-loop
Description
Caching the array length outside a loop saves reading it on each iteration, as long as the array’s length is not changed during the loop.
Affected file
- EUSDMiningIncentives.sol (Line: 94, 138)
- LybraConfigurator.sol (Line: 236)
GAS-7: Multiple address/ID mappings can be combined into a single mapping of an address/ID to a struct, where appropriate
Description
Saves a storage slot for the mapping. Depending on the circumstances and sizes of types, can avoid a Gsset (20000 gas) per mapping combined. Reads and subsequent writes can also be cheaper when a function requires both values and they both fit in the same storage slot. Finally, 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.
Affected file
- EUSD.sol (Line: 51, 56)
- EUSDMiningIncentives.sol (Line: 46, 48, 49)
- LybraConfigurator.sol (Line: 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
- LybraEUSDVaultBase.sol (Line: 28, 29, 32)
- LybraPeUSDVaultBase.sol (Line: 21, 22, 23, 24)
- ProtocolRewardsPool.sol (Line: 33, 35, 36, 37, 38)
- stakerewardV2pool.sol (Line: 33, 35, 36, 41)
GAS-8: Non-usage of specific imports
Description
The current form of relative path import is not recommended for use because it can unpredictably pollute the namespace. Instead, the Solidity docs recommend specifying imported symbols explicitly.
Affected file
- AdminTimelock.sol (Line: 5)
- EUSD.sol (Line: 5, 6, 7, 8)
- EUSDMiningIncentives.sol (Line: 12, 13, 14, 15, 16, 17)
- GovernanceTimelock.sol (Line: 5)
- LBR.sol (Line: 9, 10, 11)
- LybraConfigurator.sol (Line: 17, 18)
- LybraEUSDVaultBase.sol (Line: 5, 6, 7)
- LybraGovernance.sol (Line: 5, 6, 7)
- LybraPeUSDVaultBase.sol (Line: 5, 6, 7)
- LybraProxy.sol (Line: 5)
- LybraProxyAdmin.sol (Line: 4)
- LybraRETHVault.sol (Line: 5, 6, 7)
- LybraStETHVault.sol (Line: 5, 6)
- LybraWbETHVault.sol (Line: 5, 6, 7)
- LybraWstETHVault.sol (Line: 5, 6, 7)
- PeUSD.sol (Line: 5, 6)
- PeUSDMainnetStableVision.sol (Line: 16, 17, 18, 19)
- ProtocolRewardsPool.sol (Line: 12, 13, 14, 15, 16)
- esLBR.sol (Line: 10, 11)
- esLBRBoost.sol (Line: 5)
- stakerewardV2pool.sol (Line: 4, 5, 6)
GAS-9: Not using the named return variables when a function returns, wastes deployment gas
Description
It is not necessary to have both a named return and a return statement.
Affected file
- PeUSDMainnetStableVision.sol (Line: 167)
GAS-10: Replace modifier with function
Description
Modifiers make code more elegant, but cost more than normal functions.
Affected file
- EUSD.sol (Line: 79, 83, 87)
- EUSDMiningIncentives.sol (Line: 72)
- LybraConfigurator.sol (Line: 85, 90)
- PeUSDMainnetStableVision.sol (Line: 42, 46, 50)
- ProtocolRewardsPool.sol (Line: 178)
- stakerewardV2pool.sol (Line: 56)
GAS-11: Use assembly to write address storage values
Affected file
- EUSD.sol (Line: 93, 421, 471)
- EUSDMiningIncentives.sol (Line: 65, 66, 67, 68, 69, 73, 74, 85, 86, 90, 97, 102, 107, 112, 116, 121, 125, 126, 129, 231, 234, 239, 240)
- LBR.sol (Line: 19, 22)
- LybraConfigurator.sol (Line: 81, 82, 138, 148, 168, 188, 248, 256, 262)
- LybraEUSDVaultBase.sol (Line: 47, 48, 49, 50, 297)
- LybraGovernance.sol (Line: 40, 41, 80)
- LybraPeUSDVaultBase.sol (Line: 38, 39, 40, 41)
- LybraRETHVault.sol (Line: 24, 43)
- LybraStETHVault.sol (Line: 27)
- LybraWstETHVault.sol (Line: 26)
- PeUSD.sol (Line: 14)
- PeUSDMainnetStableVision.sol (Line: 56, 57, 60)
- ProtocolRewardsPool.sol (Line: 49, 53, 54, 55, 60, 233, 236, 238)
- esLBR.sol (Line: 23)
- stakerewardV2pool.sol (Line: 50, 51, 52, 57, 58, 123, 128, 134, 137, 142, 143)
GAS-12: Use assembly to check for address(0)
Description
Saves 6 gas per instance if using assembly to check for address(0).
assembly {
if iszero(_addr) {
mstore(0x00, "zero address")
revert(0x00, 0x20)
}
}
Affected file
- EUSD.sol (Line: 367, 368, 392, 393, 412, 441, 460)
- LybraEUSDVaultBase.sol (Line: 99, 127, 141)
- LybraPeUSDVaultBase.sol (Line: 83, 97, 111)
- PeUSDMainnetStableVision.sol (Line: 64)
GAS-13: Use constants instead of type(uintx).max
Description
It uses more gas in the distribution process and also for each transaction than constant usage.
Affected file
GAS-14: Use hardcoded address instead address(this)
Description
Instead of using address(this), it is more gas-efficient to pre-calculate and use the hardcoded address
Affected file
- GovernanceTimelock.sol (Line: 20)
- LBR.sol (Line: 43, 64)
- LybraConfigurator.sol (Line: 290, 295)
- LybraEUSDVaultBase.sol (Line: 75, 160, 171, 197, 204, 205, 260, 292, 301)
- LybraPeUSDVaultBase.sol (Line: 45, 60, 61, 62, 128, 131, 141, 174, 226, 238)
- LybraRETHVault.sol (Line: 29, 31)
- LybraStETHVault.sol (Line: 63)
- LybraWbETHVault.sol (Line: 22, 24)
- PeUSD.sol (Line: 25, 46)
- PeUSDMainnetStableVision.sol (Line: 80, 81, 82, 133, 176, 199)
- ProtocolRewardsPool.sol (Line: 195, 200)
- stakerewardV2pool.sol (Line: 85)
GAS-15: Use nested if and avoid multiple check combinations
Description
Using nested is cheaper than using && multiple check combinations. There are more advantages, such as easier to read code and better coverage reports.
Affected file
- LBR.sol (Line: 64)
- LybraEUSDVaultBase.sol (Line: 204)
- PeUSD.sol (Line: 46)
- PeUSDMainnetStableVision.sol (Line: 199)