Optimizer's optimization effectiveness varies for different opcodes.

[Subway2023]

Description

When handling overflow in mload, keccak256, the Optimizer can enable the code to run normally. However, when dealing with mstore, and extcodecopy opcodes, the Optimizer fails to prevent code execution rollback.

Environment

• Compiler version: 0.8.25
• Target EVM version (as per compiler settings): No restrictions
• Framework/IDE (e.g. Truffle or Remix): Remix
• EVM execution environment / backend / blockchain client: None
• Operating system: None

Steps to Reproduce

Compile with different compilation conditions.

mload

contract C {
  function f() public {
    assembly {
      pop(mload(4294967297))
      sstore(0, 1)
    }
  }
}

1. origin: out of gas
2. --optimize: storage: {0:1}
3. --via-ir: storage: {0:1}
4. --optimize and --via-ir: storage: {0:1}

keccak256

contract C {
  function f() external{
    assembly {
      pop(keccak256(999999999999999999999999,43486543872))
      sstore(0, 1)
    }
  }
}

1. origin: gas uint64 overflow
2. --optimize: storage: storage: {0:1}
3. --via-ir: storage: storage: {0:1}
4. --optimize and --via-ir: storage: {0:1}

mstore

contract C {
  function f() public {
    assembly {
      pop(mload(4294967297))
      sstore(0, 1)
    }
  }
}

1. origin: gas uint64 overflow
2. --optimize: storage: gas uint64 overflow
3. --via-ir: storage: gas uint64 overflow
4. --optimize and --via-ir: storage: {0:1}

extcodecopy

mstore

contract C {
  function f() external{
    assembly {
      extcodecopy(1, not(1), not(not(1)), not(1))
      sstore(0,1)
    }
  }
}

1. origin: gas uint64 overflow
2. --optimize: storage: gas uint64 overflow
3. --via-ir: storage: gas uint64 overflow
4. --optimize and --via-ir: storage: {0:1}

From the above, we can see that the Optimizer's optimization effectiveness varies for different opcodes.