Gas Optimizations

[code423n4]

Gas Optimizations

---

G-01: pre-increment ++i/--i costs less gas than post-increment i++/i--

Saves 6 gas per loop in a for loop

Total instances of this issue: 2

instance #1
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/utils/KernelUtils.sol#L49

src/utils/KernelUtils.sol

49:            i++;

instance #2
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/utils/KernelUtils.sol#L64

src/utils/KernelUtils.sol

64:            i++;

---

G-02: Length of the array (<array>.length) need not be looked up in every iteration of a for-loop

Reading array length at each iteration of the loop takes total 6 gas (3 for mload and 3 to place memory_offset) in the stack.
Caching the array.length saves around 3 gas per iteration.

Total instances of this issue: 1

instance #1
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L278

src/policies/Governance.sol

278:        for (uint256 step; step < instructions.length; ) {

---

G-03: Multiplication or Division by two should use bit shifting

<x> * 2 is the same as <x> >> 1 and <x> / 2 is the same as <x> >> 1.
MUL and DIV opcodes cost 2 gas more than SHL and SHR.

Total instances of this issue: 3

instance #1
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L419

src/policies/Operator.sol

419:            uint256 invCushionPrice = 10**(oracleDecimals * 2) / range.cushion.low.price;

instance #2
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L420

src/policies/Operator.sol

420:            uint256 invWallPrice = 10**(oracleDecimals * 2) / range.wall.low.price;

instance #3
Permalink: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L782-L787

src/policies/Operator.sol

782:            capacity =
783:                (capacity.mulDiv(
784:                    10**ohmDecimals * 10**PRICE.decimals(),
785:                    10**reserveDecimals * RANGE.price(true, true)
786:                ) * (FACTOR_SCALE + RANGE.spread(true) * 2)) /
787:                FACTOR_SCALE;

---

G-04: No need to compare boolean expressions with boolean literals, directly use the expression

if ( == true) ==> if ()
if ( == false) => if (!)

Total instances of this issue: 2

instance #1
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L223

src/policies/Governance.sol

223:        if (proposalHasBeenActivated[proposalId_] == true) {

instance #2
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Governance.sol#L306

src/policies/Governance.sol

306:        if (tokenClaimsForProposal[proposalId_][msg.sender] == true) {

---

G-05: No need to initialize non-constant/non-immutable variables to zero

Since the default value is already zero, overwriting is not required.
Saves 8 gas per instance.

Total instances of this issue: 3

instance #1
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L397

src/Kernel.sol

397:        for (uint256 i = 0; i < reqLength; ) {

instance #2
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/utils/KernelUtils.sol#L43

src/utils/KernelUtils.sol

43:    for (uint256 i = 0; i < 5; ) {

instance #3
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/utils/KernelUtils.sol#L58

src/utils/KernelUtils.sol

58:    for (uint256 i = 0; i < 32; ) {

---

G-06: Using uints/ints smaller than 256 bits increases overhead

Gas usage becomes higher with uint/int smaller than 256 bits because EVM operates on 32 bytes and uses additional operations to reduce the size from 32 bytes to the target size.

Total instances of this issue: 48

instance #1
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/Kernel.sol#L100

src/Kernel.sol

100:    function VERSION() external pure virtual returns (uint8 major, uint8 minor) {}

instance #2
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/TRSRY.sol#L51

src/modules/TRSRY.sol

51:    function VERSION() external pure override returns (uint8 major, uint8 minor) {

instance #3
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/MINTR.sol#L25

src/modules/MINTR.sol

25:    function VERSION() external pure override returns (uint8 major, uint8 minor) {

instance #4
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/RANGE.sol#L115

src/modules/RANGE.sol

115:    function VERSION() external pure override returns (uint8 major, uint8 minor) {

instance #5
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L27

src/modules/PRICE.sol

27:    event MovingAverageDurationChanged(uint48 movingAverageDuration_);

instance #6
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L28

src/modules/PRICE.sol

28:    event ObservationFrequencyChanged(uint48 observationFrequency_);

instance #7
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L44

src/modules/PRICE.sol

44:    uint32 public nextObsIndex;

instance #8
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L47

src/modules/PRICE.sol

47:    uint32 public numObservations;

instance #9
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L50

src/modules/PRICE.sol

50:    uint48 public observationFrequency;

instance #10
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L53

src/modules/PRICE.sol

53:    uint48 public movingAverageDuration;

instance #11
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L56

src/modules/PRICE.sol

56:    uint48 public lastObservationTime;

instance #12
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L59

src/modules/PRICE.sol

59:    uint8 public constant decimals = 18;

instance #13
Permalink: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L71-L77

src/modules/PRICE.sol

71:    constructor(
72:        Kernel kernel_,
73:        AggregatorV2V3Interface ohmEthPriceFeed_,
74:        AggregatorV2V3Interface reserveEthPriceFeed_,
75:        uint48 observationFrequency_,
76:        uint48 movingAverageDuration_
77:    ) Module(kernel_) {

instance #14
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L84

src/modules/PRICE.sol

84:        uint8 ohmEthDecimals = _ohmEthPriceFeed.decimals();

instance #15
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L87

src/modules/PRICE.sol

87:        uint8 reserveEthDecimals = _reserveEthPriceFeed.decimals();

instance #16
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L113

src/modules/PRICE.sol

113:    function VERSION() external pure override returns (uint8 major, uint8 minor) {

instance #17
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L127

src/modules/PRICE.sol

127:        uint32 numObs = numObservations;

instance #18
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L185

src/modules/PRICE.sol

185:        uint32 lastIndex = nextObsIndex == 0 ? numObservations - 1 : nextObsIndex - 1;

instance #19
Permalink: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L205-L208

src/modules/PRICE.sol

205:    function initialize(uint256[] memory startObservations_, uint48 lastObservationTime_)
206:        external
207:        permissioned
208:    {

instance #20
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L240

src/modules/PRICE.sol

240:    function changeMovingAverageDuration(uint48 movingAverageDuration_) external permissioned {

instance #21
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/PRICE.sol#L266

src/modules/PRICE.sol

266:    function changeObservationFrequency(uint48 observationFrequency_) external permissioned {

instance #22
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/VOTES.sol#L27

src/modules/VOTES.sol

27:    function VERSION() external pure override returns (uint8 major, uint8 minor) {

instance #23
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/modules/INSTR.sol#L28

src/modules/INSTR.sol

28:    function VERSION() public pure override returns (uint8 major, uint8 minor) {

instance #24
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L51

src/policies/Operator.sol

51:    event CushionFactorChanged(uint32 cushionFactor_);

instance #25
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L52

src/policies/Operator.sol

52:    event CushionParamsChanged(uint32 duration_, uint32 debtBuffer_, uint32 depositInterval_);

instance #26
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L53

src/policies/Operator.sol

53:    event ReserveFactorChanged(uint32 reserveFactor_);

instance #27
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L54

src/policies/Operator.sol

54:    event RegenParamsChanged(uint32 wait_, uint32 threshold_, uint32 observe_);

instance #28
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L83

src/policies/Operator.sol

83:    uint8 public immutable ohmDecimals;

instance #29
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L86

src/policies/Operator.sol

86:    uint8 public immutable reserveDecimals;

instance #30
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L89

src/policies/Operator.sol

89:    uint32 public constant FACTOR_SCALE = 1e4;

instance #31
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L371

src/policies/Operator.sol

371:            int8 priceDecimals = _getPriceDecimals(range.cushion.high.price);

instance #32
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L372

src/policies/Operator.sol

372:            int8 scaleAdjustment = int8(ohmDecimals) - int8(reserveDecimals) + (priceDecimals / 2);

instance #33
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L418

src/policies/Operator.sol

418:            uint8 oracleDecimals = PRICE.decimals();

instance #34
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L426

src/policies/Operator.sol

426:            int8 priceDecimals = _getPriceDecimals(invCushionPrice);

instance #35
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L427

src/policies/Operator.sol

427:            int8 scaleAdjustment = int8(reserveDecimals) - int8(ohmDecimals) + (priceDecimals / 2);

instance #36
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L485

src/policies/Operator.sol

485:        int8 decimals;

instance #37
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L516

src/policies/Operator.sol

516:    function setCushionFactor(uint32 cushionFactor_) external onlyRole("operator_policy") {

instance #38
Permalink: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L527-L531

src/policies/Operator.sol

527:    function setCushionParams(
528:        uint32 duration_,
529:        uint32 debtBuffer_,
530:        uint32 depositInterval_
531:    ) external onlyRole("operator_policy") {

instance #39
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L548

src/policies/Operator.sol

548:    function setReserveFactor(uint32 reserveFactor_) external onlyRole("operator_policy") {

instance #40
Permalink: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L559-L563

src/policies/Operator.sol

559:    function setRegenParams(
560:        uint32 wait_,
561:        uint32 threshold_,
562:        uint32 observe_
563:    ) external onlyRole("operator_policy") {

instance #41
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/Operator.sol#L665

src/policies/Operator.sol

665:        uint32 observe = _config.regenObserve;

instance #42
Permalink: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/PriceConfig.sol#L45-L48

src/policies/PriceConfig.sol

45:    function initialize(uint256[] memory startObservations_, uint48 lastObservationTime_)
46:        external
47:        onlyRole("price_admin")
48:    {

instance #43
Permalink: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/PriceConfig.sol#L58-L61

src/policies/PriceConfig.sol

58:    function changeMovingAverageDuration(uint48 movingAverageDuration_)
59:        external
60:        onlyRole("price_admin")
61:    {

instance #44
Permalink: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/PriceConfig.sol#L69-L72

src/policies/PriceConfig.sol

69:    function changeObservationFrequency(uint48 observationFrequency_)
70:        external
71:        onlyRole("price_admin")
72:    {

instance #45
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L85

src/policies/interfaces/IOperator.sol

85:    function setCushionFactor(uint32 cushionFactor_) external;

instance #46
Permalink: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L92-L96

src/policies/interfaces/IOperator.sol

92:    function setCushionParams(
93:        uint32 duration_,
94:        uint32 debtBuffer_,
95:        uint32 depositInterval_
96:    ) external;

instance #47
Link: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L101

src/policies/interfaces/IOperator.sol

101:    function setReserveFactor(uint32 reserveFactor_) external;

instance #48
Permalink: https://github.com/code-423n4/2022-08-olympus/blob/main/src/policies/interfaces/IOperator.sol#L109-L113

src/policies/interfaces/IOperator.sol

109:    function setRegenParams(
110:        uint32 wait_,
111:        uint32 threshold_,
112:        uint32 observe_
113:    ) external;