Michael.W基于Foundry精读Openzeppelin第60期——Clones.sol
- 0. 版本
- 0.1 Clones.sol
- 1. 目标合约
- 2. 代码精读
- 2.1 clone(address implementation) internal
- 2.2 cloneDeterministic(address implementation, bytes32 salt)
- 2.3 predictDeterministicAddress(address implementation, bytes32 salt, address deployer) internal && predictDeterministicAddress(address implementation, bytes32 salt) internal
- 3 最小代理合约的bytecode解析
- 3.1 最小代理合约的creation code解析
- 3.2 最小代理合约的runtime code解析
- 3.3 利用Foundry debugger验证最小代理合约被call时的行为
0. 版本
[openzeppelin]：v4.8.3，[forge-std]：v1.5.6
0.1 Clones.sol
Github: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v4.8.3/contracts/proxy/Clones.sol
Clones库是最小代理合约的工厂合约实现，也称之为克隆工厂。ERC1167指定了一种将全部调用都delegatecall到一个已知固定地址的最小字节码实现，它可以以一种不可变且成本极低的方式克隆目标合约。本库分别提供了使用opcode CREATE和CREATE2部署最小代理合约的方法以及CREATE2部署合约的地址预计算工具。
ERC1167详情参见：https://eips.ethereum.org/EIPS/eip-1167
1. 目标合约
封装Clones library成为一个可调用合约:
Github: https://github.com/RevelationOfTuring/foundry-openzeppelin-contracts/blob/master/src/proxy/MockClones.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;
import "openzeppelin-contracts/contracts/proxy/Clones.sol";
contract MockClones {
using Clones for address;
function clone(address implementation) external returns (address) {
return implementation.clone();
}
function cloneDeterministic(address implementation, bytes32 salt) external returns (address) {
return implementation.cloneDeterministic(salt);
}
function predictDeterministicAddress(
address implementation,
bytes32 salt,
address deployer
) external pure returns (address){
return implementation.predictDeterministicAddress(salt, deployer);
}
function predictDeterministicAddress(
address implementation,
bytes32 salt
) external view returns (address){
return implementation.predictDeterministicAddress(salt);
}
}
全部foundry测试合约：
Github: https://github.com/RevelationOfTuring/foundry-openzeppelin-contracts/blob/master/test/proxy/Clones/Clones.t.sol
测试使用的物料合约：
Github: https://github.com/RevelationOfTuring/foundry-openzeppelin-contracts/blob/master/test/proxy/Clones/Implement.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;
contract Implement {
uint public i;
address public addr;
uint[3] public fixedArray;
uint[] public dynamicArray;
mapping(uint => uint) public map;
event ImplementReceive(uint value);
event ImplementFallback(uint value);
function setUint(uint target) external {
i = target;
}
function setUintPayable(uint target) external payable {
i = target;
}
function setAddress(address target) external {
addr = target;
}
function setAddressPayable(address target) external payable {
addr = target;
}
function setFixedArray(uint[3] memory target) external {
fixedArray = target;
}
function setFixedArrayPayable(uint[3] memory target) external payable {
fixedArray = target;
}
function setDynamicArray(uint[] memory target) external {
dynamicArray = target;
}
function setDynamicArrayPayable(uint[] memory target) external payable {
dynamicArray = target;
}
function setMapping(uint key, uint value) external {
map[key] = value;
}
function setMappingPayable(uint key, uint value) external payable {
map[key] = value;
}
function triggerRevert() external pure {
revert("Implement: revert");
}
function triggerRevertPayable() external payable {
revert("Implement: revert");
}
function getPure() external pure returns (string memory){
return "pure return value";
}
receive() external payable {
emit ImplementReceive(msg.value);
}
fallback() external payable {
emit ImplementFallback(msg.value);
}
}
2. 代码精读
2.1 clone(address implementation) internal
使用opcode CREATE来部署一个最小代理合约（implementation是其背后的逻辑合约地址）并返回该合约地址。该方法等同于克隆一个implementation合约。
function clone(address implementation) internal returns (address instance) {
/// @solidity memory-safe-assembly
// 内联汇编
assembly {
// shr(0xe8, shl(0x60, implementation))：implementation地址左移96位后再右移232位，构造出一个"低24位为implementation地址高24位，其余高位均为0"的数
// or(shr(0xe8, shl(0x60, implementation)), 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000)：将implementation地址高24位接到0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000尾部
// mstore(0x00, or(shr(0xe8, shl(0x60, implementation)), 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000))：
// 将拼接后的字节码存入position 0开始的内存中，该word中存储的数值为：
// 0x0000000000000000003d602d80600a3d3981f3363d3d373d3d3d363d73 + implementation地址的高24位
mstore(0x00, or(shr(0xe8, shl(0x60, implementation)), 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000))
// or(shl(0x78, implementation), 0x5af43d82803e903d91602b57fd5bf3)：implementation地址左移120位后尾部追加0x5af43d82803e903d91602b57fd5bf3
// mstore(0x20, or(shl(0x78, implementation), 0x5af43d82803e903d91602b57fd5bf3)):
// 将拼接后的字节码存入position 0x20开始的内存中，该word中存储的数值为
// implementation地址的后256-120=136位 + 0x5af43d82803e903d91602b57fd5bf3
// 注：此时内存前两个word中存储的内容合为0x0000000000000000003d602d80600a3d3981f3363d3d373d3d3d363d73 + implementation地址 + 0x5af43d82803e903d91602b57fd5bf3
mstore(0x20, or(shl(0x78, implementation), 0x5af43d82803e903d91602b57fd5bf3))
// 使用opcode CREATE来部署合约。返回新部署的合约地址。
// 第一个参数：部署合约传入的eth value
// 第二个参数：bytecode在内存中的起始position，即第9个字节开始
// 第三个参数：bytecode在内存中的字节长度，即55个字节
instance := create(0, 0x09, 0x37)
}
// 如果返回地址为0地址表示部署失败
require(instance != address(0), "ERC1167: create failed");
}
foundry代码验证：
contract ClonesTest is Test {
MockClones private _testing = new MockClones();
Implement private _implement = new Implement();
function test_Clone() external {
address minimalProxyAddrCloneByOpCreate = _testing.clone(address(_implement));
testsForMinimalProxyClone(minimalProxyAddrCloneByOpCreate);
}
event ImplementReceive(uint value);
event ImplementFallback(uint value);
function testsForMinimalProxyClone(address minimalProxyAddress) private {
Implement minimalProxy = Implement(payable(minimalProxyAddress));
uint proxyBalance = minimalProxyAddress.balance;
uint ethValue = 1 wei;
assertEq(proxyBalance, 0);
// case 1: test for both writing slot and return data in type uint256
assertEq(minimalProxy.i(), 0);
assertEq(_implement.i(), 0);
// call without eth value
minimalProxy.setUint(1024);
assertEq(minimalProxy.i(), 1024);
assertEq(_implement.i(), 0);
// call with eth value
minimalProxy.setUintPayable{value: ethValue}(2048);
assertEq(minimalProxy.i(), 2048);
assertEq(_implement.i(), 0);
assertEq(minimalProxyAddress.balance, proxyBalance + ethValue);
proxyBalance = minimalProxyAddress.balance;
// case 2: test for both writing slot and return data in type address
assertEq(minimalProxy.addr(), address(0));
assertEq(_implement.addr(), address(0));
// call without eth value
minimalProxy.setAddress(address(1024));
assertEq(minimalProxy.addr(), address(1024));
assertEq(_implement.addr(), address(0));
// call with eth value
minimalProxy.setAddressPayable{value: ethValue}(address(2048));
assertEq(minimalProxy.addr(), address(2048));
assertEq(_implement.addr(), address(0));
assertEq(minimalProxyAddress.balance, proxyBalance + ethValue);
proxyBalance = minimalProxyAddress.balance;
// case 3: test for both writing slot and return data in type fixed array
assertEq(minimalProxy.fixedArray(0), 0);
assertEq(_implement.fixedArray(0), 0);
// call without eth value
uint[3] memory targetFixedArray = [uint(1024), 2048, 4096];
minimalProxy.setFixedArray(targetFixedArray);
for (uint i; i < targetFixedArray.length; ++i) {
assertEq(minimalProxy.fixedArray(i), targetFixedArray[i]);
assertEq(_implement.fixedArray(i), 0);
}
// call with eth value
targetFixedArray = [uint(2048), 4096, 8192];
minimalProxy.setFixedArrayPayable{value: ethValue}(targetFixedArray);
for (uint i; i < targetFixedArray.length; ++i) {
assertEq(minimalProxy.fixedArray(i), targetFixedArray[i]);
assertEq(_implement.fixedArray(i), 0);
}
assertEq(minimalProxyAddress.balance, proxyBalance + ethValue);
proxyBalance = minimalProxyAddress.balance;
// case 4: test for both writing slot and return data in type dynamic array
// revert when make a staticcall to an uninitialized dynamic array with the length 0
vm.expectRevert();
minimalProxy.dynamicArray(0);
vm.expectRevert();
_implement.dynamicArray(0);
// call without eth value
uint[] memory targetDynamicArray = new uint[](3);
targetDynamicArray[0] = 1024;
targetDynamicArray[1] = 2048;
targetDynamicArray[2] = 4096;
minimalProxy.setDynamicArray(targetDynamicArray);
for (uint i; i < targetDynamicArray.length; ++i) {
assertEq(minimalProxy.dynamicArray(i), targetDynamicArray[i]);
vm.expectRevert();
assertEq(_implement.dynamicArray(i), 0);
}
// call with eth value
targetDynamicArray[0] = 2048;
targetDynamicArray[1] = 4096;
targetDynamicArray[2] = 8192;
minimalProxy.setDynamicArrayPayable{value: ethValue}(targetDynamicArray);
for (uint i; i < targetDynamicArray.length; ++i) {
assertEq(minimalProxy.dynamicArray(i), targetDynamicArray[i]);
vm.expectRevert();
assertEq(_implement.dynamicArray(i), 0);
}
assertEq(minimalProxyAddress.balance, proxyBalance + ethValue);
proxyBalance = minimalProxyAddress.balance;
// case 5: test for both writing slot and return data in type mapping
uint key = 1024;
uint value = 2048;
assertEq(minimalProxy.map(key), 0);
assertEq(_implement.map(key), 0);
// call without eth value
minimalProxy.setMapping(key, value);
assertEq(minimalProxy.map(key), value);
assertEq(_implement.map(key), 0);
// call with eth value
key += 1024;
minimalProxy.setMappingPayable{value: ethValue}(key, value);
assertEq(minimalProxy.map(key), value);
assertEq(_implement.map(key), 0);
assertEq(minimalProxyAddress.balance, proxyBalance + ethValue);
proxyBalance = minimalProxyAddress.balance;
// case 6: test for reverting with msg
// call without eth value
vm.expectRevert("Implement: revert");
minimalProxy.triggerRevert();
vm.expectRevert("Implement: revert");
_implement.triggerRevert();
// call with eth value
vm.expectRevert("Implement: revert");
minimalProxy.triggerRevertPayable{value: ethValue}();
vm.expectRevert("Implement: revert");
_implement.triggerRevertPayable{value: ethValue}();
// case 7: test for calling pure (staticcall)
assertEq(minimalProxy.getPure(), "pure return value");
assertEq(_implement.getPure(), "pure return value");
// case 8: test call with eth value
// go into receive() without calldata
vm.expectEmit(minimalProxyAddress);
emit ImplementReceive(ethValue);
(bool ok,) = minimalProxyAddress.call{value: ethValue}("");
assertTrue(ok);
assertEq(minimalProxyAddress.balance, proxyBalance + ethValue);
proxyBalance = minimalProxyAddress.balance;
// go into fallback() with calldata of unknown function selector
vm.expectEmit(minimalProxyAddress);
emit ImplementFallback(ethValue);
bytes memory calldata_ = abi.encodeWithSignature("unknown()");
(ok,) = minimalProxyAddress.call{value: ethValue}(calldata_);
assertTrue(ok);
assertEq(minimalProxyAddress.balance, proxyBalance + ethValue);
// case 9: test call without eth value
// go into receive() without calldata
vm.expectEmit(minimalProxyAddress);
emit ImplementReceive(0);
(ok,) = minimalProxyAddress.call("");
assertTrue(ok);
// go into fallback() with calldata of unknown function selector
vm.expectEmit(minimalProxyAddress);
emit ImplementFallback(0);
(ok,) = minimalProxyAddress.call(calldata_);
assertTrue(ok);
}
}
2.2 cloneDeterministic(address implementation, bytes32 salt)
使用opcode CREATE2来部署一个最小代理合约（implementation是其背后的逻辑合约地址，salt为使用CREATE2时传入的随机数）并返回该合约地址。该方法等同于克隆一个implementation合约。
function cloneDeterministic(address implementation, bytes32 salt) internal returns (address instance) {
/// @solidity memory-safe-assembly
// 内联汇编
assembly {
// shr(0xe8, shl(0x60, implementation))：implementation地址左移96位后再右移232位，构造出一个"低24位为implementation地址高24位，其余高位均为0"的数
// or(shr(0xe8, shl(0x60, implementation)), 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000)：将implementation地址高24位接到0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000尾部
// mstore(0x00, or(shr(0xe8, shl(0x60, implementation)), 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000))：
// 将拼接后的字节码存入position 0开始的内存中，该word中存储的数值为：
// 0x0000000000000000003d602d80600a3d3981f3363d3d373d3d3d363d73 + implementation地址的高24位
mstore(0x00, or(shr(0xe8, shl(0x60, implementation)), 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000))
// or(shl(0x78, implementation), 0x5af43d82803e903d91602b57fd5bf3)：implementation地址左移120位后尾部追加0x5af43d82803e903d91602b57fd5bf3
// mstore(0x20, or(shl(0x78, implementation), 0x5af43d82803e903d91602b57fd5bf3)):
// 将拼接后的字节码存入position 0x20开始的内存中，该word中存储的数值为
// implementation地址的后256-120=136位 + 0x5af43d82803e903d91602b57fd5bf3
// 注：此时内存前两个word中存储的内容合为0x0000000000000000003d602d80600a3d3981f3363d3d373d3d3d363d73 + implementation地址 + 0x5af43d82803e903d91602b57fd5bf3
mstore(0x20, or(shl(0x78, implementation), 0x5af43d82803e903d91602b57fd5bf3))
// 使用opcode CREATE2来部署合约。返回新部署的合约地址。
// 第一个参数：部署合约传入的eth value
// 第二个参数：bytecode在内存中的起始position，即第9个字节开始
// 第三个参数：bytecode在内存中的字节长度，即55个字节
// 第四个参数：随机数
instance := create2(0, 0x09, 0x37, salt)
}
// 如果返回地址为0地址表示部署失败
require(instance != address(0), "ERC1167: create2 failed");
}
foundry代码验证：
contract ClonesTest is Test {
MockClones private _testing = new MockClones();
Implement private _implement = new Implement();
function test_CloneDeterministic() external {
bytes32 salt = keccak256("salt");
address minimalProxyAddrCloneByOpCreate2 = _testing.cloneDeterministic(address(_implement), salt);
testsForMinimalProxyClone(minimalProxyAddrCloneByOpCreate2);
// revert if clone by opcode CREATE2 with the same salt again
vm.expectRevert("ERC1167: create2 failed");
_testing.cloneDeterministic(address(_implement), salt);
}
}
2.3 predictDeterministicAddress(address implementation, bytes32 salt, address deployer) internal && predictDeterministicAddress(address implementation, bytes32 salt) internal
predictDeterministicAddress(address implementation, bytes32 salt, address deployer) internal：预计算使用地址为deployer的合约（该合约使用了Clones库）的cloneDeterministic(address,bytes32) internal方法部署的最小代理合约地址；predictDeterministicAddress(address implementation, bytes32 salt) internal：预计算调用本合约（本合约使用了Clones库）的cloneDeterministic(address,bytes32) internal方法部署的最小代理合约地址。
function predictDeterministicAddress(
address implementation,
bytes32 salt,
address deployer
) internal pure returns (address predicted) {
/// @solidity memory-safe-assembly
// 内联汇编
assembly {
// 获取内存中的空闲指针
let ptr := mload(0x40)
// 将deployer写入position ptr+56开始的一个word的内存中（[ptr+56, ptr+88]）
// 此时，20个字节deployer地址具体存储在[ptr+68, prt+88]内存中
mstore(add(ptr, 0x38), deployer)
// 将0x5af43d82803e903d91602b57fd5bf3ff写入position ptr+36开始的一个word的内存中（[ptr+36, ptr+68]）
// 此时，0x5af43d82803e903d91602b57fd5bf3ff具体存储在[ptr+52, prt+68]内存中
// 注：0x5af43d82803e903d91602b57fd5bf3为最小代理合约的runtime code，0xff为计算CREATE2部署合约地址的起始标志位
mstore(add(ptr, 0x24), 0x5af43d82803e903d91602b57fd5bf3ff)
// 将逻辑合约地址写入position ptr+20开始的一个word的内存中（[ptr+20, ptr+52]）
// 此时，20个字节的逻辑合约地址具体存储在[ptr+32, prt+52]内存中
mstore(add(ptr, 0x14), implementation)
// 将0x3d602d80600a3d3981f3363d3d373d3d3d363d73写入position ptr开始的一个word的内存中（[ptr, ptr+32]）
// 此时，0x3d602d80600a3d3981f3363d3d373d3d3d363d73具体存储在[ptr+12, prt+32]内存中
mstore(ptr, 0x3d602d80600a3d3981f3363d3d373d3d3d363d73)
// 该时刻[ptr+12, ptr+67]的内存中已经拼成了最小代理合约的creation code：
/*********************************************************************************
[MEMORY]
| ptr ~ ptr+11 | ptr+12 ~ ptr+31 | ptr+32 ~ ptr+51 |
00 ~ 00 0x3d602d80600a3d3981f3363d3d373d3d3d363d73 逻辑合约地址
---------------------------------------------------------------------------------
| ptr+52 ~ ptr+66 | ptr+67
0x5af43d82803e903d91602b57fd5bf3 0xff
**********************************************************************************/
// 将salt写入position ptr+88开始的一个word的内存中（[ptr+88, ptr+120]）
mstore(add(ptr, 0x58), salt)
// keccak256(add(ptr, 0x0c), 0x37)：计算[ptr+12, ptr+67]内存中数据的hash值，即计算最小代理合约的creation code的hash
// 将最小代理合约的creation code hash写入position ptr+120开始的一个word的内存中（[ptr+120, ptr+152]）
mstore(add(ptr, 0x78), keccak256(add(ptr, 0x0c), 0x37))
// 该时刻[ptr+67, ptr+152]的内存中内容如下：
/*********************************************************************************
[MEMORY]
| ptr+67 | ptr+68 ~ ptr+87 | ptr+88 ~ ptr+119 | ptr+120 ~ ptr+151 |
0xff deployer地址 salt值 最小代理合约的creation code hash
**********************************************************************************/
// 计算[ptr+67, ptr+67+85]内存中数据的hash值
// 将这个256位的hash值转成address（即截取低160为）就是CREATE2将部署出的合约地址
predicted := keccak256(add(ptr, 0x43), 0x55)
}
}
function predictDeterministicAddress(address implementation, bytes32 salt)
internal
view
returns (address predicted)
{
// deployer为本合约地址，调用predictDeterministicAddress(address,bytes32,address)
return predictDeterministicAddress(implementation, salt, address(this));
}
}
foundry代码验证：
contract ClonesTest is Test {
MockClones private _testing = new MockClones();
Implement private _implement = new Implement();
function test_PredictDeterministicAddress() external {
address implementationAddr = address(_implement);
bytes32 salt = keccak256("salt");
// test for predictDeterministicAddress(address,bytes32)
assertEq(
_testing.predictDeterministicAddress(implementationAddr, salt),
_testing.cloneDeterministic(implementationAddr, salt)
);
// test for predictDeterministicAddress(address,bytes32,address)
salt = keccak256("other salt");
assertEq(
_testing.predictDeterministicAddress(implementationAddr, salt, address(_testing)),
_testing.cloneDeterministic(implementationAddr, salt)
);
}
}
3 最小代理合约的bytecode解析
从Clones库中的的clone()可知，进入opcode CREATE的bytecode参数为：
0x3d602d80600a3d3981f3 + 0x363d3d373d3d3d363d73 + implementation地址 + 0x5af43d82803e903d91602b57fd5bf3
以上bytecode可以等同理解为是最小代理合约的creation code。
部署后的最小代理合约的runtime code为：
0x363d3d373d3d3d363d73 + implementation地址 + 0x5af43d82803e903d91602b57fd5bf3
3.1 最小代理合约的creation code解析
creation code其实就是：
0x3d602d80600a3d3981f3 + runtime code
0x3d602d80600a3d3981f3翻译成操作码及执行后对应stack空间如下：
OPCODE | STACK
[00] RETURNDATASIZE | [0]
[01] PUSH1 2d | [2d, 0]
[03] DUP1 | [2d, 2d, 0]
[04] PUSH1 0a | [a, 2d, 2d, 0]
[06] RETURNDATASIZE | [0, a, 2d, 2d, 0]
[07] CODECOPY | [2d, 0]
[08] DUP2 | [0, 2d, 0]
[09] RETURN | []
对应内联汇编代码为：
assembly{
// 将creation code从position 10(0xa)开始复制45(0x2d)个字节到内存中
// 内存存储的起始position为returndatasize()
codecopy(returndatasize(), 0x0a, 0x2d)
// 结束执行，返回数据是内存中[returndatasize(): returndatasize()+45]的内容，即最小代理的runtime code
return (returndatasize(), 0x2d)
}
综上，creation code多出来的bytecode的逻辑其实就是将runtime code写入内存中，并返回runtime code。return后，evm会更新全局状态，包括新合约的runtime code、地址等，即runtime code上链。
3.2 最小代理合约的runtime code解析
最小代理合约的runtime code为：
0x363d3d373d3d3d363d73 + implementation地址 + 0x5af43d82803e903d91602b57fd5bf3
runtime code翻译成操作码及执行后对应stack空间如下：
注：
cs：当前call携带的calldata字节长度
rs1：最近一次的return data字节长度(delegatecall之前)
rs2：最近一次的return data字节长度(delegatecall之后)
i_addr: implementation地址
gas: 目前剩余的可用gas
res: delegatecall的执行结果（调用成功为1，失败为0）
OPCODE | STACK
[00] CALLDATASIZE | [cs]
[01] RETURNDATASIZE | [rs1, cs]
[02] RETURNDATASIZE | [rs1, rs1, cs]
[03] CALLDATACOPY | []
[04] RETURNDATASIZE | [rs1]
[05] RETURNDATASIZE | [rs1, rs1]
[06] RETURNDATASIZE | [rs1, rs1, rs1]
[07] CALLDATASIZE | [cs, rs1, rs1, rs1]
[08] RETURNDATASIZE | [rs1, cs, rs1, rs1, rs1]
[09] PUSH20 i_addr | [i_addr, rs1, cs, rs1, rs1, rs1]
[1e] GAS | [gas, i_addr, rs1, cs, rs1, rs1, rs1]
[1f] DELEGATECALL | [res, rs1]
[20] RETURNDATASIZE | [rs2, res, rs1]
[21] DUP3 | [rs1, rs2, res, rs1]
[22] DUP1 | [rs1, rs1, rs2, res, rs1]
[23] RETURNDATACOPY | [res, rs1]
[24] SWAP1 | [rs1, res]
[25] RETURNDATASIZE | [rs2, rs1, res]
[26] SWAP2 | [res, rs1, rs2]
[27] PUSH1 2b | [2b, res, rs1, rs2]
[29] JUMPI | [rs1, rs2]
# 如果res为0，执行REVERT
[2a] REVERT | []
# 如果res非0，执行JUMPDEST
[2b] JUMPDEST | [rs1, rs2]
[2c] RETURN | []
对应内联汇编代码为：
assembly{
// 逻辑合约地址
let i_addr := {硬编码逻辑合约地址}
// delegatecall之前最近一次的return data字节长度
let rs1 := returndatasize()
// 将本次的calldata复制到[rs1, rs1+calldatasize()]的内存中
calldatacopy(rs1, rs1, calldatasize())
// delegatecall到逻辑合约。
// 携带的calldata来自[rs1, rs1+calldatasize()]的内存，返回值存储在[rs1,rs1]的内存中。
let res := delegatecall(gas(), i_addr, rs1, calldatasize(), rs1, rs1)
// 获取delegatecall后的return data字节长度
let rs2 := returndatasize()
// 将delegatecall的return data复制到[rs1, rs1+rs2]的内存中
returndatacopy(rs1, rs1, rs2)
// 判断delegatecall是否成功
switch res
// 不成功
case 0 {
// revert，携带的msg为delegatecall的return data
revert(rs1, rs2)
}
// 成功
default {
// 终止执行，返回delegatecall的return data
return (rs1, rs2)
}
}
3.3 利用Foundry debugger验证最小代理合约被call时的行为
在Foundry debugger中观察当最小代理合约被call时的行为：
$ forge test --debug "test_CallClone"
按j键执行opcode CALL，evm的context会立刻切换到最小代理合约内：
之后会按照3.2中分析的那样：最小代理合约会delegatecall到它背后的逻辑合约（携带当前call的calldata）：
ps:
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