Reserve contest - pavankv's results

1 .Using Solidity version 0.8.17 will provide an overall gas optimization

Using at least 0.8.10 will save gas due to skipped extcodesize check if there is a return value. Currently the contracts are compiled using version 0.8.7 (Foundry default). It is easily changeable to 0.8.17 using the command sed -i 's/0.8.7/^0.8.0/' test/*.sol && sed -i '4isolc = "0.8.17"' foundry.toml. This will have the following total savings obtained by forge snapshot --diff | tail -1

code snippet:- https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/Component.sol#L2 And all scoped files .

2 . Use assembly to check for address(0)

Use assembly to check for address(0) Saves 6 gas per instance if using assembly to check for address(0) e.g.

assembly { if iszero(_addr) { mstore(0x00, "zero address") revert(0x00, 0x20) } }

code snippet:- https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/Component.sol#L34 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/RecollateralizationLib.sol#L401 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/Trading.sol#L68 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Deployer.sol#L109 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/RevenueTrader.sol#L29

3 . Usage of uints/ints smaller than 32 bytes (256 bits) incurs overhead

When using elements that are smaller than 32 bytes, your contract’s gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller than that, the EVM must use more operations in order to reduce the size of the element from 32 bytes to the desired size https://docs.soliditylang.org/en/v0.8.11/internals/layout_in_storage.html\ Use a larger size then downcast where needed

code snippet:- https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Broker.sol#L24 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Broker.sol#L37 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BasketHandler.sol#L134 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BasketHandler.sol#L135 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/Trading.sol#L20 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Distributor.sol#L34 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/Trading.sol#L21 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/Trading.sol#L28 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/Trading.sol#L31 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/Trading.sol#L33 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BackingManager.sol#L33 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BackingManager.sol#L34 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BackingManager.sol#L36 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BackingManager.sol#L37

4 .Expressions that cannot be overflowed can be unchecked :-

code snippet:- https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/Trading.sol#L72 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/mixins/Trading.sol#L121 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BasketHandler.sol#L621 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BasketHandler.sol#L636 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Distributor.sol#L128 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Distributor.sol#L133

5 .Increments/decrements can be unchecked in for-loops

In Solidity 0.8+, there’s a default overflow check on unsigned integers. It’s possible to uncheck this in for-loops and save some gas at each iteration, but at the cost of some code readability, as this uncheck cannot be made inline.

code snippet:- https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BasketHandler.sol#L70 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BasketHandler.sol#L78 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/BasketHandler.sol#L218 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Distributor.sol#L108

6. Split the require statement :-

Split the require statement instead of && because it cost 3 gas .

code snippet:- https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L813 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L821 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Broker.sol#L135 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Furnace.sol#L89 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/RToken.sol#L410 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/RToken.sol#L813 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/RToken.sol#L741 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/RToken.sol#L590 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/RevenueTrader.sol#L72

7. Multiple accesses of a mapping/array should use a local variable cache :-

Caching a mapping's value in a local storage or calldata variable when the value is accessed multiple times saves ~42 gas per access due to not having to perform the same offset calculation every time. Help the Optimizer by saving a storage variable's reference instead of repeatedly fetching it To help the optimizer,declare a storage type variable and use it instead of repeatedly fetching the reference in a map or an array. As an example, instead of repeatedly calling someMap[someIndex], save its reference like this: SomeStruct storage someStruct = someMap[someIndex] and use it

code snippet:- https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L68 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L60

8. Use calldata instead of memory

When a function with a memory array is called externally, the abi.decode() step has to use a for-loop to copy each index of the calldata to the memory index. Each iteration of this for-loop costs at least 60 gas (i.e. 60 * <mem_array>.length). Using calldata directly bypasses this loop. If the array is passed to an internal function which passes the array to another internal function where the array is modified and therefore memory is used in the external call, it’s still more gas-efficient to use calldata when the external function uses modifiers, since the modifiers may prevent the internal functions from being called. Structs have the same overhead as an array of length one.

code snippet:- https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Deployer.sol#L103 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Deployer.sol#L104 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/Deployer.sol#L107

9 .Use immutable instead of constant for keccak256 operation :-

The use of constant keccak variables results in extra hashing (and so gas). This results in the keccak operation being performed whenever the variable is used and called, increasing gas costs relative to just storing the output hash. Changing to immutable will only perform hashing on contract deployment which will save gas. You should use immutables until the referenced issues are implemented, then you only pay the gas costs for the computation at deploy time.

code snippet:- https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L126 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSRVotes.sol#L27

10. Use x = x+y instead of x+=y for state variable :-

code snippet: https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L229 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L387 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L396 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L402 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L403 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L412 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L417 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L513 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L549 https://github.com/reserve-protocol/protocol/blob/df7ecadc2bae74244ace5e8b39e94bc992903158/contracts/p1/StRSR.sol#L698