QuickSwap and StellaSwap contest - francoHacker's results

STRUCT PACKING TO SAVE GAS:

Normally there's no benefit to using these sub-types because Solidity reserves 256 bits of storage regardless of the uint size. For example, using uint8 instead of uint (uint256) won't save you any gas.

But there's an exception to this: inside structs.

If you have multiple uints inside a struct, using a smaller-sized uint when possible will allow Solidity to pack these variables together to take up less storage. For example:

<> struct NormalStruct { uint a; uint b; uint c; }

struct MiniMe { uint32 a; uint32 b; uint c; }

// mini will cost less gas than normal because of struct packing NormalStruct normal = NormalStruct(10, 20, 30); MiniMe mini = MiniMe(10, 20, 30); </>

For this reason, inside a struct you'll want to use the smallest integer sub-types you can get away with.

You'll also want to cluster identical data types together (i.e. put them next to each other in the struct) so that Solidity can minimize the required storage space. For example, a struct with fields uint c; uint32 a; uint32 b; will cost less gas than a struct with fields uint32 a; uint c; uint32 b; because the uint32 fields are clustered together.

INSTANCES:

https://github.com/code-423n4/2022-09-quickswap/blob/main/src/core/contracts/AlgebraPool.sol#L41-L675-L692

https://github.com/code-423n4/2022-09-quickswap/blob/main/src/core/contracts/libraries/AdaptiveFee.sol#L10