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@AmazingAng
AmazingAng authored Sep 4, 2023
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Expand Up @@ -41,33 +41,31 @@ wherein the bytes at indices 9 - 28 (inclusive) are replaced with the 20 byte ad

The disassembly of the standard proxy contract code:

```shell
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
```
| 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. 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 suc 0 rds |
| [27] | 57 | JUMPI | 0 rds |
| [29] | fd | REVERT | |
| [2a] | 5b | JUMPDEST | 0 rds |
| [2b] | f3 | RETURN | |

### Minimal Creation Code

Expand Down Expand Up @@ -140,42 +138,40 @@ The contract is built from [first principals](https://blog.openzeppelin.com/deep

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

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

```shell
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
| 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. 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`.

```shell
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
| 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
Expand All @@ -185,16 +181,16 @@ Lastly we need to return the data or revert the transaction based on whether the
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`.

```shell
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
| 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 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`:
Expand Down

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