Gas: Optimize Conditional Statements in IndexTemplate.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 IndexTemplate.sol:deposit(), the code is as follows:

172:         if (_supply > 0 && _totalLiquidity > 0) {  
173:             _mintAmount = (_amount * _supply) / _totalLiquidity;
174:         } else if (_supply > 0 && _totalLiquidity == 0) {
175:             //when
176:             _mintAmount = _amount * _supply;
177:         } else {
178:             _mintAmount = _amount;
179:         }

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

      if (_supply == 0) {
          _mintAmount = _amount;
      } else if (_totalLiquidity == 0) { // @audit-info : implicit _supply > 0 as above condition is false
          _mintAmount = _amount * _supply;
      } else { // @audit-info : implicit _supply > 0 and _totalLiquidity > 0 as both the previous conditions are false
          _mintAmount = (_amount * _supply) / _totalLiquidity;
      }

Tools Used

VS Code

Recommended Mitigation Steps

Compact conditions in mentioned logic statements

[oishun1112]

#285

different contract but same reason

[oishun1112]

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

#355