Gas: Optimize Conditional Statements in CDSTemplate.sol:deposit()

[code423n4]

Handle

Dravee

Vulnerability details

Impact

It's possible to save gas by optimizing the checks in conditional statements (if, else if and else). This would save a few opcodes and avoid redundant checks.

Proof of Concept

In CDSTemplate.sol:deposit(), the code is as follows:

140:         if (_supply > 0 && _liquidity > 0) { 
141:             _mintAmount = (_amount * _supply) / _liquidity;
142:         } else if (_supply > 0 && _liquidity == 0) {
143:             //when vault lose all underwritten asset = 
144:             _mintAmount = _amount * _supply; //dilute LP token value af. Start CDS again.
145:         } else {
146:             //when _supply == 0,
147:             _mintAmount = _amount;
148:         }

The conditions checks can be optimized with the following (read the @audit-info comments for futher information):

        if (_supply == 0) { 
            _mintAmount = _amount;
        } else if (_liquidity == 0) { // @audit-info : implicit _supply > 0 as above condition is false
            //when vault lose all underwritten asset = 
            _mintAmount = _amount * _supply; //dilute LP token value af. Start CDS again.
        } else { // @audit-info : implicit _supply > 0 and _liquidity > 0 as both the previous conditions are false
            _mintAmount = (_amount * _supply) / _liquidity;
        }

Tools Used

VS Code

Recommended Mitigation Steps

Compact conditions in mentioned logic statements

[oishun1112]

most of the case will be _supply > 0 && _liquidity > 0
so, it is cheaper to keep this order of validations

[oishun1112]

I performed experiment and confirmed that even above premise, this impl reduce gas

#355