Adding unchecked directive can save gas

[code423n4]

Handle

WatchPug

Vulnerability details

For the arithmetic operations that will never over/underflow, using the unchecked directive (Solidity v0.8 has default overflow/underflow checks) can save some gas from the unnecessary internal over/underflow checks.

For example:

• LeveragedPool.sol#intervalPassed()

  https://github.com/tracer-protocol/perpetual-pools-contracts/blob/646360b0549962352fe0c3f5b214ff8b5f73ba51/contracts/implementation/LeveragedPool.sol#L259-L261

      function intervalPassed() public view override returns (bool) {
          return block.timestamp >= lastPriceTimestamp + updateInterval;
      }

  lastPriceTimestamp + updateInterval will never overlow.

• LeveragedPool.sol#executePriceChange()

  https://github.com/tracer-protocol/perpetual-pools-contracts/blob/646360b0549962352fe0c3f5b214ff8b5f73ba51/contracts/implementation/LeveragedPool.sol#L175-L204

  emit PoolRebalance(
      int256(newShortBalance) - int256(_shortBalance),
      int256(newLongBalance) - int256(_longBalance)
  );

  int256(newShortBalance) - int256(_shortBalance) and int256(newLongBalance) - int256(_longBalance) will never underflow.

[CalabashSquash]

Duplicate of #34

Although #27 does provide more in-depth examples.

[GalloDaSballo]

Agree with finding