cameel

Chromosome: xiDslifaCrDLLujnxmIuVsetcuTjersOvjmnu
Program: erc20.sol-ERC20.yul
{
    mstore(64, 128)
    if iszero(lt(calldatasize(), 4))
    {
        switch shr(224, calldataload(0))
        case 0x095ea7b3 {
            if callvalue() { revert(0, 0) }
            let param_0, param_1 := abi_decode_tuple_t_addresst_uint256(4, calldatasize())

cameel

pragma solidity ^0.7.0;

// SPDX-License-Identifier: GPLv3

contract PrologContract {
    struct Term {
        string value;      // If empty, term is a list, otherwise it's a predicate.
                           // value can represent an atom, variable, | or _.
        Term[] children;
    }

cameel

Use cases

• Optional/nullable data types.
• Variant data types.
• Flag with extra information needed only in some cases (or different in different cases).
• Modeling states in a state machine where each state can have some data associated with it.
• List of operations for batch processing, where each operation can have its own arguments.
• Alternative to function overloading that allows avoiding combinatorial explosion when there are multiple parameters that need variants.
• Nested data structures with heterogenous nodes.

Syntax and semantics

cameel

# Default sequence from solc 0.8.24

dhfoDgvulfnTUtnIf                # None of these can make stack problems worse
[
    xa[r]EscLM                   # Turn into SSA and simplify
    cCTUtTOntnfDIul              # Perform structural simplification
    Lcul                         # Simplify again
    Vcul [j]                     # Reverse SSA

    # should have good "compilability" property here.

cameel

# Default sequence from solc 0.8.24 adjusted to stay in SSA form instead of reversing it in each cycle.
# Minimal version - only removes the `Vcul [j]` bit.

dhfoDgvulfnTUtnIf                # None of these can make stack problems worse
[
    xa[r]EscLM                   # Turn into SSA and simplify
    cCTUtTOntnfDIul              # Perform structural simplification
    Lcul                         # Simplify again

    # should have good "compilability" property here.

cameel

default/ramanujan_pi/soltest-input

cameel

single-pass/ramanujan_pi/soltest-input

cameel

always-ssa-min/ramanujan_pi/soltest-input

cameel

solc-seqbench

https://github.com/cameel/solc-seqbench

Analysis pipeline

Workflow

• Define inputs
  • optimizer sequences
  • contracts
• sequences of external calls with parameters

cameel

# Default sequence from solc 0.8.24 with only a single iteration of the main loop

dhfoDgvulfnTUtnIf               # None of these can make stack problems worse

xa[r]EscLM                      # Turn into SSA and simplify
cCTUtTOntnfDIul                 # Perform structural simplification
Lcul                            # Simplify again
Vcul [j]                        # Reverse SSA

# should have good "compilability" property here.