Tcr 11 gas optimisations

[CalabashSquash]

Motivation

TCR-11 In the Sigma Prime audit report listed numerous gas saving changes that should be made.

Changes

LeveragedPool

• Remove unnecessary uint256( cast
• Add function getUpkeepInformation() external view override returns (int256 _latestPrice, uint256 _lastPriceTimestamp, uint256 _updateInterval)
  • This is used by PoolKeeper to avoid three separate external calls
• Make getOraclePrice external
  PoolCommitter
• Cache LeveragedPool.tokens locally, to save external calls on these.
  • Since these don't change for a given pool, it is safe to set them when setQuoteAndPool is called.
• In executeAllCommitments, nextEarliestCommitUnexecuted was always being set to equal i at the start of each iteration. May as well just remove i.
• There were unnecessary SLOAD of latestCommitUnexecuted each loop (it is checked inside the for statement, and used inside the block). This was removed and just SLOAD'ed once at the start of the function.
• Make getCommit external
  PoolFactory
• Make the addresses for pairTokenBase and poolBase immutable.
  • These are read from in deployment, but never change.
• Move pool.initialize(initialization); above poolCommitter.setQuoteAndPool so that LeveragedPool.tokens is initialised before setQuoteAndPool, allowing this function to save LeveragedPool.tokens.
  • See PoolCommitter
    PoolKeeper
• Use LeveragedPool.getOraclePrice in newPool instead of 1) fetching oracleWrapper then 2) fetching price from oracleWrapper
• Use getUpkeepInformation in performUpkeepSinglePool.
  • See LeveragedPool. But this is to save from 3 external calls.
    PoolSwapLibrary
• Make getBalancesAfterFees and calculatePriceChange external.
• In getLossMultiplier, a Ternary can be used to save from confusing logic and extra mathematical operations.
• In calculatePriceChange, A line can be removed which sets totalFeeAmount right before setting it again two lines below.
  hardhat.config.ts
• Add optimizer