Branchless isHealthy

[MathisGD]

isHealthy could be branchless:

could be branchless 🤓

    function isHealthy(Market calldata market, Id id, address user) private view returns (bool) {
        uint borrowValue = borrowShare[id][user].wMul(totalBorrow[id]).uwDiv(totalBorrowShares[id]).wMul(market.borrowableOracle.price());
        uint collateralValue = collateral[id][user].wMul(market.collateralOracle.price());
        return collateralValue.wMul(market.lLTV) >= borrowValue;
    }

with

    /// @dev Rounds towards zero.
    function uwDiv(uint x, uint y) internal pure returns (uint z) {
        // This part is "checked".
        z = x * WAD;
        // This part is "unchecked".
        assembly {
            z := div(z, y)
        }
    }

It uses the fact that div(x, 0) outputs 0.

From #4 (comment)

[Rubilmax]

uwDiv is very close to wDiv. I am against such naming.

wadDiv is better, and unsafeWadDiv is more easily distinguishable.

[MathisGD]

I really like wDiv, but you are right we should probably go for unsafeWDiv for this one

[MathisGD]

I don't think that we want this kind of low-level optis finally