morpho-org/morpho-blue-irm

Morpho Blue Interest Rate Models

morpho-blue-irm's Issues

Make the min/max rate immutables

I think that the min/max rate at target could be immutables actually (we already considered changing them in #64), but this can be done in another PR

Originally posted by @QGarchery in #66 (review)

Refactor repo orga with the repo split

There is no event emission

The Irm has a storage per market; values are not logged when modified.

I suggest adding an event during the borrowRate update.

L-03 Missing Docstrings

N-02 Variable Cast Is Unnecessary

rename files after #54

Contract name is too general

• There is no information about the specification of the Irm in the name. It can become harder to refer to this IRM when other irm are whitelisted.

I suggest adding a specific name for this IRM, such as PidIrm.

add test for underestimation

morpho-blue-irm/src/AdaptiveCurveIrm.sol

Lines 135 to 136 in c2b1732

	// Note that the speed is assumed constant between two interactions, but in theory it increases because of
	// interests. So the rate will be slightly underestimated.

quantify and test this underestimation

`avgBorrowRate` uses the unbounded value of `newBorrowRate`

Context

https://github.com/morpho-labs/morpho-blue-irm/blob/8440cb45c70866542330b97db0b8ebc03aec284b/src/SpeedJumpIrm.sol#L152

Issue

avgBorrowRate is calculated using the unbounded value of newBorrowRate, so there may be a case where newBorrowRate > MAX_RATE leading to avgBorrowRate being over-evaluated with regard to the bounded value newBorrowRate returned by _borrowRate
The same applies symmetrically to the minimum bound

Update equality comment

We may want to clarify that the following equality is not correct when endRateAtTarget has been bounded.

https://github.com/morpho-labs/morpho-blue-irm/blob/77ed9c17917bba7a7175702cb23f33e1ba5697cd/src/SpeedJumpIrm.sol#L144-L145

For reference: #73

Make parameters constant

https://morpholabs.slack.com/archives/C02N7CZ088N/p1700917459949969

Test living vertigo mutations

Mutation testing report:
Number of mutations:    75
Killed:                 50 / 75

Mutations:
Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/src/AdaptiveCurveIrm.sol
    Line nr: 75
    Result: Lived
    Original line:
                 require(curveSteepness <= ConstantsLib.MAX_CURVE_STEEPNESS, ErrorsLib.INPUT_TOO_LARGE);

    Mutated line:
                 require(curveSteepness < ConstantsLib.MAX_CURVE_STEEPNESS, ErrorsLib.INPUT_TOO_LARGE);


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/src/AdaptiveCurveIrm.sol
    Line nr: 77
    Result: Lived
    Original line:
                 require(adjustmentSpeed <= ConstantsLib.MAX_ADJUSTMENT_SPEED, ErrorsLib.INPUT_TOO_LARGE);

    Mutated line:
                 require(adjustmentSpeed < ConstantsLib.MAX_ADJUSTMENT_SPEED, ErrorsLib.INPUT_TOO_LARGE);


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/src/AdaptiveCurveIrm.sol
    Line nr: 78
    Result: Lived
    Original line:
                 require(targetUtilization < WAD, ErrorsLib.INPUT_TOO_LARGE);

    Mutated line:
                 require(targetUtilization <= WAD, ErrorsLib.INPUT_TOO_LARGE);


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/src/AdaptiveCurveIrm.sol
    Line nr: 79
    Result: Lived
    Original line:
                 require(targetUtilization > 0, ErrorsLib.ZERO_INPUT);

    Mutated line:
                 require(targetUtilization >= 0, ErrorsLib.ZERO_INPUT);


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/src/AdaptiveCurveIrm.sol
    Line nr: 81
    Result: Lived
    Original line:
                 require(initialRateAtTarget <= ConstantsLib.MAX_RATE_AT_TARGET, ErrorsLib.INPUT_TOO_LARGE);

    Mutated line:
                 require(initialRateAtTarget < ConstantsLib.MAX_RATE_AT_TARGET, ErrorsLib.INPUT_TOO_LARGE);


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/src/AdaptiveCurveIrm.sol
    Line nr: 121
    Result: Lived
    Original line:
                 int256 errNormFactor = utilization > TARGET_UTILIZATION ? WAD - TARGET_UTILIZATION : TARGET_UTILIZATION;

    Mutated line:
                 int256 errNormFactor = utilization >= TARGET_UTILIZATION ? WAD - TARGET_UTILIZATION : TARGET_UTILIZATION;


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/src/libraries/adaptive-curve/ExpLib.sol
    Line nr: 27
    Result: Lived
    Original line:
                     if (x < LN_WEI_INT) return 0;

    Mutated line:
                     if (x <= LN_WEI_INT) return 0;


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/src/libraries/adaptive-curve/ExpLib.sol
    Line nr: 33
    Result: Lived
    Original line:
                     int256 roundingAdjustment = (x < 0) ? -(LN_2_INT / 2) : (LN_2_INT / 2);

    Mutated line:
                     int256 roundingAdjustment = (x <= 0) ? -(LN_2_INT / 2) : (LN_2_INT / 2);


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/lib/morpho-blue/src/libraries/MathLib.sol
    Line nr: 32
    Result: Lived
    Original line:
                 return (x * y + (d - 1)) / d;

    Mutated line:
                 return (x * y + (d - 1)) * d;


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/lib/morpho-blue/src/libraries/MathLib.sol
    Line nr: 32
    Result: Lived
    Original line:
                 return (x * y + (d - 1)) / d;

    Mutated line:
                 return (x * y - (d - 1)) / d;


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/lib/morpho-blue/src/libraries/MathLib.sol
    Line nr: 32
    Result: Lived
    Original line:
                 return (x * y + (d - 1)) / d;

    Mutated line:
                 return (x / y + (d - 1)) / d;


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/lib/morpho-blue/src/libraries/MathLib.sol
    Line nr: 32
    Result: Lived
    Original line:
                 return (x * y + (d - 1)) / d;

    Mutated line:
                 return (x * y + (d + 1)) / d;


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/lib/morpho-blue/src/libraries/MathLib.sol
    Line nr: 42
    Result: Lived
    Original line:
                 return firstTerm + secondTerm + thirdTerm;

    Mutated line:
                 return firstTerm + secondTerm - thirdTerm;


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/lib/morpho-blue/src/libraries/MathLib.sol
    Line nr: 42
    Result: Lived
    Original line:
                 return firstTerm + secondTerm + thirdTerm;

    Mutated line:
                 return firstTerm - secondTerm + thirdTerm;


Mutation:
    File: /home/rubilmax/sites/morpho.xyz/morpho-blue-irm/src/libraries/adaptive-curve/ConstantsLib.sol
    Line nr: 17
    Result: Lived
    Original line:
             int256 internal constant MAX_ADJUSTMENT_SPEED = int256(1_000 ether) / 365 days;

    Mutated line:
             int256 internal constant MAX_ADJUSTMENT_SPEED = int256(1_000 ether) * 365 days;

`LN2_INT` could be internal to be used by integrators (include in the test suite)

Context

https://github.com/morpho-labs/morpho-blue-irm/blob/8440cb45c70866542330b97db0b8ebc03aec284b/src/libraries/MathLib.sol#L20

Issue

Instead of being able to uint256(MathLib.LN2_INT), an integrator has to define again LN2_INT (or its uint256 equivalent)

remove the necessity of yarn test:forge

Extend testing suite

### Tasks
- [x] (MIN/MAX) value

Typo in license

https://github.com/morpho-labs/morpho-blue-irm/blob/bdf8ee061d6da8d1c19b53e70854fc5b83324b5e/src/libraries/UtilsLib.sol#L1C29-L1C39

Rate can go to zero ?

And be stuck there forever ?

Remove the exponential aspect of the curve

(consideration assuming #54)

even if there are some logical arguments in favor of keeping it, it is likely that it will make no change in practice so I'm in favor of removing it

discussion: https://morpholabs.slack.com/archives/C02N7CZ088N/p1698624167103969

Update security contract to `[email protected]`

`via-ir` -> `via_ir`

`SpeedJumpIrm` doesn't compile without IR

Write README

Investigate 100% utilized markets with hardhat

Higher the minimum rate ?

Currently the minimum rate is 1e-18 per second, which is very low (~1e-11% APR). If a market is abandoned and then re-used, this very low rate might take a long time to come back to reasonable values. Maybe it could be capped to something higher.

Add OZ report to `audits` folder

Check that the max rate corresponds with what makes morpho not revert

Some values could be stored as constants in `MathLib`

Context

https://github.com/morpho-labs/morpho-blue-irm/blob/8440cb45c70866542330b97db0b8ebc03aec284b/src/libraries/MathLib.sol#L25-L28

Issue

These values could be used by integrators so we may consider exposing them as library constants

Write additionnal documentation about IRM initial parameters

The SPEED_FACTOR can be used by seconds or by year. Maybe it's worth writing that in this code it is by second (while the one used by Matthieu was by year)

General IRM test suite

https://github.com/cantinasec/review-morpho/issues/18#issuecomment-1976019504

N-04 Unused Import

Update blue onced frozen

Not compound rate variation ?

          I seriously wonder if it is not a bit overkill. This computation cost a non-negligible amount of gas, and it is complex: it requires to ensure that there are no overflow in a computation up to a power of 12 (and it has also a limit when the linear variation is < -3).

Something simpler like

        uint256 variationMultiplier = WAD_INT + linearVariation;

would not have those issues. I understand that we would lose the property that having multiple updates in an interval is the same as having one update at the end, but this is only a third order loss in the worst case:

• approximating an amount is a first order precision issue
• approximating the rate (for example linear instead of compounded) is a second order precision issue
• approximating the variation of the rate is a third order precision issue

It was already unclear for rates if it was worth the extra computation cost, it may be the case here that it's not worth at all

Originally posted by @QGarchery in #1 (comment)

readme update

with fixed rate irm

Optimize wExp

There is this idea by @QGarchery, and probably other ideas. I estimate the current two wExp to be responsible for a little bit more than half of the total gas cost of the borrowRate function

Test that the IRM never reverts under any conditions on Morpho

Update to last blue version

chore(irm): add licence

Update submodule to `morpho-org/morpho-blue`