Yul ERC20

NOT MEANT FOR PRODUCTION - UNAUDITED - USE AT OWN RISK

ERC20 implementations using only inline assembly YUL. Basically, hyper gas optimized ERC20 base implementations for solidity developers. It improves on gas consupmtion for every public / external method over the leading ERC20.sol implementations (OpenZeppelin, Solmate). Optimizing view/pure calls can matter too, as many ERC20 view methods get used inside of state changing methods. See below for full gas comparison.

Note that there are two separate slightly differing implementations ERC20.sol and ERC20External.sol in this repository. Use ERC20External.sol for additional gas savings if your ERC20 doesn't need internal (i.e. same contract including inheritors) access to any of these functions: transfer(), transferFrom(), approve(), allowance(), balanceOf(), nonces(), totalSupply(), name(), symbol(), decimals(). All the basic getter functions can still be accessed easily via internal state variables and so are not needed, and the remaining functions are usually not needed as an internal subroutine; thus most ERC20s, especially simple ones, should benefit from the ERC20External.sol implementation gas savings. For those that want to utilize any of the listed functions in thier contracts that inherit and extend the base implementation, they can use ERC20.sol instead (gas usage only increases by 0-100 gas in most functions).

This is also useful as a reference implementation to learn the basics of inline assembly if you are already familiar with canonical solidity ERC20 implementations. There are comments with solidity translations for lines in yul.

Usage

install with

npm install yulerc20

then you could import this as your base ERC20 contract implementation:

import {ERC20} from "yulerc20/contracts/ERC20.sol";

or

import {ERC20External} from "yulerc20/contracts/ERC20External.sol";

STILL HIGHLY EXPERIMENTAL - NOT YET MEANT FOR PRODUCTION

Test

fill in ALCHEMY_ID in a .env (see .env.example for all environment vars)

yarn

yarn compile

yarn test

Gas Comparison

• Solc version: 0.8.13
• Optimizer enabled: true
• Runs: 999999

approve

Contract	Gas Cost
OpenZeppelinERC20	46232
SolmateERC20	46153
YulERC20	46080
YulERC20External	46008

permit

Contract	Gas Cost
SolmateERC20	74172
YulERC20	73774
YulERC20External	73762

transfer

Contract	Gas Cost
OpenZeppelinERC20	51496
SolmateERC20	51251
YulERC20	51167
YulERC20External	51073

transferFrom

Contract	Gas Cost
OpenZeppelinERC20	33697
SolmateERC20	31995
YulERC20	31748
YulERC20External	31688

allowance

Contract	Gas Cost
OpenZeppelinERC20	24578
SolmateERC20	24557
YulERC20	24557
YulERC20External	24503

balanceOf

Contract	Gas Cost
OpenZeppelinERC20	23993
SolmateERC20	23984
YulERC20	23987
YulERC20External	23939

burn

Contract	Gas Cost
OpenZeppelinERC20	28900
SolmateERC20	28768
YulERC20	28646
YulERC20External	28646

decimals

Contract	Gas Cost
OpenZeppelinERC20	21286
SolmateERC20	21313
YulERC20	21286
YulERC20External	21262

mint

Contract	Gas Cost
OpenZeppelinERC20	51317
SolmateERC20	51194
YulERC20	51118
YulERC20External	51118

name

Contract	Gas Cost
OpenZeppelinERC20	24284
SolmateERC20	24276
YulERC20	21571
YulERC20External	21281

symbol

Contract	Gas Cost
OpenZeppelinERC20	24282
SolmateERC20	24274
YulERC20	21580
YulERC20External	21279

totalSupply

Contract	Gas Cost
OpenZeppelinERC20	23413
SolmateERC20	23427
YulERC20	23413
YulERC20External	23385