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Add EIP: Minimal Proxy Contract with PUSH0
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---
eip: 7511
title: Minimal Proxy Contract with PUSH0
description: Optimizes the previous Minimal Proxy Contract with the PUSH0 opcode
author: 0xAA (@AmazingAng), vectorized (@Vectorized), 0age (@0age)
discussions-to: https://ethereum-magicians.org/t/erc-7511-minimal-proxy-contract-with-push0/15662
status: Draft
type: Standards Track
category: ERC
created: 2023-09-04
requires: 7, 211, 1167, 3855
---

## Abstract

With the `PUSH0` opcode ([EIP-3855](./eip-3855.md)), introduced with the Shanghai upgrade, we optimized the previous Minimal Proxy Contract ([ERC-1167](./eip-1167.md)) by 200 gas at deployment and 5 gas at runtime, while retaining the same functionality.

## Motivation


1. Reduce the contract bytecode size by `1` byte by removing a redundant `SWAP` opcode.
2. Reduce the runtime gas by replacing two `DUP` (cost `3` gas each) with two `PUSH0` (cost `2` gas each).
3. Increase the readability of the proxy contract by redesigning it from first principles with `PUSH0`.

## Specification

### Standard Proxy Contract

The exact runtime code for the minimal proxy contract with `PUSH0` is:

```
365f5f375f5f365f73bebebebebebebebebebebebebebebebebebebebe5af43d5f5f3e5f3d91602a57fd5bf3
```

where the bytes at indices 9 - 28 (inclusive) are replaced with the 20-byte address of the master implementation contract. The length of the runtime code is `44` bytes.

The disassembly of the new minimal proxy contract code is:

| pc | op | opcode | stack |
|------|--------|----------------|--------------------|
| [00] | 36 | CALLDATASIZE | cds |
| [01] | 5f | PUSH0 | 0 cds |
| [02] | 5f | PUSH0 | 0 0 cds |
| [03] | 37 | CALLDATACOPY | |
| [04] | 5f | PUSH0 | 0 |
| [05] | 5f | PUSH0 | 0 0 |
| [06] | 36 | CALLDATASIZE | cds 0 0 |
| [07] | 5f | PUSH0 | 0 cds 0 0 |
| [08] | 73bebe.| PUSH20 0xbebe. | 0xbebe. 0 cds 0 0 |
| [1d] | 5a | GAS | gas 0xbebe. 0 cds 0 0|
| [1e] | f4 | DELEGATECALL | suc |
| [1f] | 3d | RETURNDATASIZE | rds suc |
| [20] | 5f | PUSH0 | 0 rds suc |
| [21] | 5f | PUSH0 | 0 0 rds suc |
| [22] | 3e | RETURNDATACOPY | suc |
| [23] | 5f | PUSH0 | 0 suc |
| [24] | 3d | RETURNDATASIZE | rds 0 suc |
| [25] | 91 | SWAP2 | suc 0 rds |
| [26] | 602a | PUSH1 0x2a | 0x2a suc 0 rds |
| [27] | 57 | JUMPI | 0 rds |
| [29] | fd | REVERT | |
| [2a] | 5b | JUMPDEST | 0 rds |
| [2b] | f3 | RETURN | |

### Minimal Creation Code

The minimal creation code of the minimal proxy contract is:

```
602c8060095f395ff3365f5f375f5f365f73bebebebebebebebebebebebebebebebebebebebe5af43d5f5f3e5f3d91602a57fd5bf3
```

where the first 9 bytes are the initcode:

```
602c8060095f395ff3
```

And the rest are runtime/contract code of the proxy. The length of the creation code is `53` bytes.

### Deploy with Solidity

The minimal proxy contract can be deployed with Solidity using the following contract:

```solidity
// SPDX-License-Identifier: CC0-1.0
pragma solidity ^0.8.20;
// Note: this contract requires `PUSH0`, which is available in solidity > 0.8.20 and EVM version > Shanghai
contract Clone0Factory {
error FailedCreateClone();
receive() external payable {}
/**
* @dev Deploys and returns the address of a clone0 (Minimal Proxy Contract with `PUSH0`) that mimics the behaviour of `implementation`.
*
* This function uses the create opcode, which should never revert.
*/
function clone0(address impl) public payable returns (address addr) {
// first 18 bytes of the creation code
bytes memory data1 = hex"602c8060095f395ff3365f5f375f5f365f73";
// last 15 bytes of the creation code
bytes memory data2 = hex"5af43d5f5f3e5f3d91602a57fd5bf3";
// complete the creation code of Clone0
bytes memory _code = abi.encodePacked(data1, impl, data2);
// deploy with create op
assembly {
// create(v, p, n)
addr := create(callvalue(), add(_code, 0x20), mload(_code))
}
if (addr == address(0)) {
revert FailedCreateClone();
}
}
}
```

## Rationale

The optimized contract is constructed with essential components of the proxy contract and incorporates the recently added `PUSH0` opcode. The core elements of the minimal proxy include:

1. Copy the calldata with `CALLDATACOPY`.
2. Forward the calldata to the implementation contract using `DELEGATECALL`.
3. Copy the returned data from the `DELEGATECALL`.
4. Return the results or revert the transaction based on whether the `DELEGATECALL` is successful.

### Step 1: Copy the Calldata

To copy the calldata, we need to provide the arguments for the `CALLDATACOPY` opcodes, which are `[0, 0, cds]`, where `cds` represents calldata size.

| pc | op | opcode | stack |
|------|--------|----------------|--------------------|
| [00] | 36 | CALLDATASIZE | cds |
| [01] | 5f | PUSH0 | 0 cds |
| [02] | 5f | PUSH0 | 0 0 cds |
| [03] | 37 | CALLDATACOPY | |

### Step 2: Delegatecall

To forward the calldata to the delegate call, we need to prepare arguments for the `DELEGATECALL` opcodes, which are `[gas 0xbebe. 0 cds 0 0]`, where `gas` represents the remaining gas, `0xbebe.` represents the address of the implementation contract, and `suc` represents whether the delegatecall is successful.

| pc | op | opcode | stack |
|------|--------|----------------|--------------------|
| [04] | 5f | PUSH0 | 0 |
| [05] | 5f | PUSH0 | 0 0 |
| [06] | 36 | CALLDATASIZE | cds 0 0 |
| [07] | 5f | PUSH0 | 0 cds 0 0 |
| [08] | 73bebe.| PUSH20 0xbebe. | 0xbebe. 0 cds 0 0 |
| [1d] | 5a | GAS | gas 0xbebe. 0 cds 0 0|
| [1e] | f4 | DELEGATECALL | suc |

### Step 3: Copy the Returned Data from the `DELEGATECALL`

To copy the returndata, we need to provide the arguments for the `RETURNDATACOPY` opcodes, which are `[0, 0, red]`, where `rds` represents size of returndata from the `DELEGATECALL`.

| pc | op | opcode | stack |
|------|--------|----------------|--------------------|
| [1f] | 3d | RETURNDATASIZE | rds suc |
| [20] | 5f | PUSH0 | 0 rds suc |
| [21] | 5f | PUSH0 | 0 0 rds suc |
| [22] | 3e | RETURNDATACOPY | suc |

### Step 4: Return or Revert

Lastly, we need to return the data or revert the transaction based on whether the `DELEGATECALL` is successful. There is no `if/else` in opcodes, so we need to use `JUMPI` and `JUMPDEST` instead. The arguments for `JUMPI` is `[0x2a, suc]`, where `0x2a` is the destination of the conditional jump.

We also need to prepare the argument `[0, rds]` for `REVERT` and `RETURN` opcodes before the `JUMPI`, otherwise we have to prepare them twice. We cannot avoid the `SWAP` operation, because we can only get `rds` after the `DELEGATECALL`.

| pc | op | opcode | stack |
|------|--------|----------------|--------------------|
| [23] | 5f | PUSH0 | 0 suc |
| [24] | 3d | RETURNDATASIZE | rds 0 suc |
| [25] | 91 | SWAP2 | suc 0 rds |
| [26] | 602a | PUSH1 0x2a | 0x2a suc 0 rds |
| [27] | 57 | JUMPI | 0 rds |
| [29] | fd | REVERT | |
| [2a] | 5b | JUMPDEST | 0 rds |
| [2b] | f3 | RETURN | |

In the end, we arrived at the runtime code for Minimal Proxy Contract with `PUSH0`:

```
365f5f375f5f365f73bebebebebebebebebebebebebebebebebebebebe5af43d5f5f3e5f3d91602a57fd5bf3
```

The length of the runtime code is `44` bytes, which reduced `1` byte from the previous Minimal Proxy Contract. Moreover, it replaced the `RETURNDATASIZE` and `DUP` operations with `PUSH0`, which saves gas and increases the readability of the code. In summary, the new Minimal Proxy Contract reduces `200` gas at deployment and `5` gas at runtime, while remaining the same functionalities as the old one.

## Backwards Compatibility

Because the new minimal proxy contract uses `PUSH0` opcode, it can only be deployed after the Shanghai Upgrade. It behaves the same as the previous Minimal Proxy Contract.

## Security Considerations

The new proxy contract standard is identical to the previous one (ERC-1167). Here are the security considerations when using minimal proxy contracts:

1. **Non-Upgradability**: Minimal Proxy Contracts delegate their logic to another contract (often termed the "implementation" or "logic" contract). This delegation is fixed upon deployment, meaning you can't change which implementation contract the proxy delegates to after its creation.

2. **Initialization Concerns**: Proxy contracts lack constructors, so you need to use an initialization function after deployment. Skipping this step could leave the contract unsafe.

3. **Safety of Logic Contract**: Vulnerabilities in the logic contract affect all associated proxy contracts.

4. **Transparency Issues**: Because of its complexity, users might see the proxy as an empty contract, making it challenging to trace back to the actual logic contract.

## Copyright

Copyright and related rights waived via [CC0](../LICENSE.md).

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