Frankencoin - ReyAdmirado's results

1. state variables should be cached in stack variables rather than re-reading them from storage

Caching of a state variable replace each Gwarmaccess (100 gas) with a much cheaper stack read. Other less obvious fixes/optimizations include having local memory caches of state variable structs, or having local caches of state variable contracts/addresses.

minters[_minter] should be cached before #L294 because the is a high possibilty of it being read twice from storage

• Frankencoin.sol#L294

possible 97 gas save with risking loss of only 3 gas. if the check passes we save 97 for the second minted read and if it fails we just lose 3 gas. cache it before this line

• Position.sol#L349

minted should be cached before #L141 because its being read at least twice. first read is in the condition in #L141 in case the condition succeeds its gonna be read in the #L142 which could be prevented by using the cached version. in case the condition in #L141 fails its gonna be read in #L149.

• Position.sol#L141-L150

2. can make the variable outside the loop to save gas

make the variable outside the loop and only give the value to variable inside

current

• Equity.sol#L193
• Equity.sol#L313

j

• Equity.sol#L196

3. Ternary over if ... else

Using ternary operator instead of the if else statement saves gas. the placed that it make sense are listed here

• Position.sol#L121-L125

• Position.sol#L160-L164

• Position.sol#L184-L188

• Position.sol#L250-L254

• Frankencoin.sol#L141-L144

• Frankencoin.sol#L207-L211

• Frankencoin.sol#L282-L287

4. Use assembly to check for address(0)

saves 6 gas per instance

• ERC20.sol#L152

• ERC20.sol#L180

• ERC20PermitLight.sol#L56

5. before some functions we should check some variables for possible gas save

before transfer we should check for amount being 0 so the function doesnt run when its not gonna do anything

check amount

• Position.sol#L228

• Position.sol#L253

• Position.sol#L269

• MintingHub.sol#L110

• MintingHub.sol#L129

• MintingHub.sol#L142

• MintingHub.sol#L284

• Frankencoin.sol#L283

freedAmount - _amountExcludingReserve

• Frankencoin.sol#L254

reserveLeft

• Frankencoin.sol#L285

6. Non-strict inequalities are cheaper than strict ones

In the EVM, there is no opcode for non-strict inequalities (>=, <=) and two operations are performed (> + = or < + =). consider replacing >= with the strict counterpart > and add - 1 to the second side

• Position.sol#L53

• Position.sol#L110

• Position.sol#L184

• Position.sol#L305

• Position.sol#L307

• Position.sol#L374

• MintingHub.sol#L109

• MintingHub.sol#L171

• MintingHub.sol#L172

• MintingHub.sol#L201

• MintingHub.sol#L218

• MintingHub.sol#L255

• Equity.sol#L136

• Equity.sol#L244

• Equity.sol#L247

• Frankencoin.sol#L141

• Frankencoin.sol#L282

• Frankencoin.sol#L294

• ERC20PermitLight.sol#L30

• StablecoinBridge.sol#L50

• StablecoinBridge.sol#L51