Gas Optimizations

[code423n4]

• Not sure why withdrawFees queries the receiver from the masterContract (itself):

  function withdrawFees() public {
    address to = masterContract.feeTo();

  There is a variable named feeTo which is supposed to receive fees, so it should probably be cheapier to directly read it.

• Repeated calculations should be cached, e.g. totalShare - openFeeShare in function _lend could be extracted to a variable:

  bentoBox.balanceOf(asset, address(this)) >= (totalShare - openFeeShare + protocolFeeShare + feesEarnedShare)
  
  bentoBox.transfer(asset, lender, address(this), totalShare - openFeeShare + protocolFeeShare);
  
  uint256 borrowerShare = totalShare - openFeeShare;

• Using uint8 does not give any efficiency, actually, it is the opposite as EVM operates on default of 256-bit values so uint8 is more expensive in this case as it needs a conversion. It only gives improvements in cases where you can pack variables together, e.g. structs.

  uint8[] calldata actions,
  
  uint8 internal constant ACTION_REPAY = 2;
  uint8 internal constant ACTION_REMOVE_COLLATERAL = 4;
  
  uint8 internal constant ACTION_REQUEST_LOAN = 12;
  uint8 internal constant ACTION_LEND = 13;
  
  // Function on BentoBox
  uint8 internal constant ACTION_BENTO_DEPOSIT = 20;
  uint8 internal constant ACTION_BENTO_WITHDRAW = 21;
  uint8 internal constant ACTION_BENTO_TRANSFER = 22;
  uint8 internal constant ACTION_BENTO_TRANSFER_MULTIPLE = 23;
  uint8 internal constant ACTION_BENTO_SETAPPROVAL = 24;
  
  // Any external call (except to BentoBox)
  uint8 internal constant ACTION_CALL = 30;
  
  // Signed requests
  uint8 internal constant ACTION_REQUEST_AND_BORROW = 40;
  uint8 internal constant ACTION_TAKE_COLLATERAL_AND_LEND = 41;

• I don't think this library is used in any meaningful way:

  using RebaseLibrary for Rebase;

[cryptolyndon]

Seen, thanks.