PegStabilityModule Code Style Findings

PSM-01C: Inefficient Re-Calculation of Fee Percentages

Type	Severity	Location
Gas Optimization		PegStabilityModule.sol:L26, L27, L67, L71, L75, L79

Description:

The referenced statements will constantly perform a known subtraction due to mixing constant and immutable values.

Example:

Copy
66function quoteToUnderlyingGivenIn(uint256 amountIn) public view returns (uint256) {
67    return amountIn * (BPS_SCALE - TO_UNDERLYING_FEE) / BPS_SCALE;
68}
69
70function quoteToUnderlyingGivenOut(uint256 amountOut) public view returns (uint256) {
71    return amountOut * BPS_SCALE / (BPS_SCALE - TO_UNDERLYING_FEE);
72}
73
74function quoteToSynthGivenIn(uint256 amountIn) public view returns (uint256) {
75    return amountIn * (BPS_SCALE - TO_SYNTH_FEE) / BPS_SCALE;
76}
77
78function quoteToSynthGivenOut(uint256 amountOut) public view returns (uint256) {
79    return amountOut * BPS_SCALE / (BPS_SCALE - TO_SYNTH_FEE);
80}

Recommendation:

We advise the code to instead assign the result of the subtraction to the relevant immutable variables, optimizing each referenced statement by one subtraction operation.

Alleviation (fb2dd77a6ff9b7f710edb48e7eb5437e0db4fc1a):

The Euler Finance team evaluated this exhibit and opted to acknowledge it as they do not believe the minimal gas savings to justify the introduction of extra code and an immutable variable.