ultra_circuit_checker.cpp

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#include "ultra_circuit_checker.hpp"
#include "barretenberg/common/assert.hpp"
#include "barretenberg/flavor/mega_flavor.hpp"
#include "barretenberg/stdlib/primitives/circuit_builders/circuit_builders.hpp"
#include <unordered_set>
 
namespace bb {
 
template <> auto UltraCircuitChecker::init_empty_values<UltraCircuitBuilder_<UltraExecutionTraceBlocks>>()
{
    return UltraFlavor::AllValues{};
}
 
template <> auto UltraCircuitChecker::init_empty_values<MegaCircuitBuilder_<bb::fr>>()
{
    return MegaFlavor::AllValues{};
}
 
template <>
UltraCircuitBuilder_<UltraExecutionTraceBlocks> UltraCircuitChecker::prepare_circuit<
    UltraCircuitBuilder_<UltraExecutionTraceBlocks>>(const UltraCircuitBuilder_<UltraExecutionTraceBlocks>& builder_in)
{
    // Create a copy of the input circuit
    UltraCircuitBuilder_<UltraExecutionTraceBlocks> builder{ builder_in };
    if (!builder.circuit_finalized) { // avoid warnings about finalizing an already finalized circuit
        builder.finalize_circuit();
    }
 
    return builder;
}
 
template <>
MegaCircuitBuilder_<bb::fr> UltraCircuitChecker::prepare_circuit<MegaCircuitBuilder_<bb::fr>>(
    const MegaCircuitBuilder_<bb::fr>& builder_in)
{
    // Create a copy of the input circuit
    MegaCircuitBuilder_<bb::fr> builder{ builder_in };
 
    // Deepcopy the opqueue to avoid modifying the original one
    builder.op_queue = std::make_shared<ECCOpQueue>(*builder.op_queue);
 
    if (!builder.circuit_finalized) { // avoid warnings about finalizing an already finalized circuit
        builder.finalize_circuit();
    }
 
    return builder;
}
 
template <typename Builder> bool UltraCircuitChecker::check(const Builder& builder_in)
{
    if (builder_in.failed()) {
        info("CircuitChecker: circuit contains invalid witnesses: ", builder_in.err());
    }
 
    Builder builder = UltraCircuitChecker::prepare_circuit(builder_in);
 
    // Construct a hash table for lookup table entries to efficiently determine if a lookup gate is valid
    LookupHashTable lookup_hash_table;
    for (const auto& table : builder.get_lookup_tables()) {
        const FF table_index(table.table_index);
        for (size_t i = 0; i < table.size(); ++i) {
            lookup_hash_table.insert({ table.column_1[i], table.column_2[i], table.column_3[i], table_index });
        }
    }
 
    // Instantiate structs used for checking tag and memory record correctness
    TagCheckData tag_data;
    MemoryCheckData memory_data{ builder };
 
    bool result = true;
    size_t block_idx = 0;
    for (auto& block : builder.blocks.get()) {
        result = result && check_block(builder, block, tag_data, memory_data, lookup_hash_table);
        if (!result) {
#ifndef FUZZING_DISABLE_WARNINGS
            info("Failed at block idx = ", block_idx);
#else
            (void)block_idx;
#endif
            return false;
        }
        block_idx++;
    }
 
#ifdef ULTRA_FUZZ
    result = result & relaxed_check_delta_range_relation(builder);
    if (!result) {
        return false;
    }
    result = result & relaxed_check_memory_relation(builder);
    if (!result) {
        return false;
    }
#endif
#ifndef ULTRA_FUZZ
    // Tag check is only expected to pass after entire execution trace (all blocks) have been processed
    result = result && check_tag_data(tag_data);
    if (!result) {
        info("Failed tag check.");
        return false;
    }
#endif
 
    return result;
};
 
template <typename Builder>
bool UltraCircuitChecker::check_block(Builder& builder,
                                      auto& block,
                                      TagCheckData& tag_data,
                                      MemoryCheckData& memory_data,
                                      LookupHashTable& lookup_hash_table)
{
    // Initialize empty AllValues of the correct Flavor based on Builder type; for input to Relation::accumulate
    auto values = init_empty_values<Builder>();
    Params params;
    params.eta = memory_data.eta; // used in Memory relation for RAM/ROM consistency
    params.eta_two = memory_data.eta_two;
    params.eta_three = memory_data.eta_three;
 
    auto report_fail = [&](const char* message, size_t row_idx) {
#ifndef FUZZING_DISABLE_WARNINGS
        info(message, row_idx);
#else
        (void)message;
        (void)row_idx;
#endif
#ifdef CHECK_CIRCUIT_STACKTRACES
        block.stack_traces.print(row_idx);
#endif
        return false;
    };
 
    // Perform checks on each gate defined in the builder
    bool result = true;
    for (size_t idx = 0; idx < block.size(); ++idx) {
 
        populate_values(builder, block, values, tag_data, memory_data, idx);
 
        result = result && check_relation<Arithmetic>(values, params);
        if (!result) {
            return report_fail("Failed Arithmetic relation at row idx = ", idx);
        }
        result = result && check_relation<Elliptic>(values, params);
        if (!result) {
            return report_fail("Failed Elliptic relation at row idx = ", idx);
        }
#ifndef ULTRA_FUZZ
        result = result && check_relation<Memory>(values, params);
        if (!result) {
            return report_fail("Failed Memory relation at row idx = ", idx);
        }
        result = result && check_relation<NonNativeField>(values, params);
        if (!result) {
            return report_fail("Failed NonNativeField relation at row idx = ", idx);
        }
        result = result && check_relation<DeltaRangeConstraint>(values, params);
        if (!result) {
            return report_fail("Failed DeltaRangeConstraint relation at row idx = ", idx);
        }
#else
        // Bigfield related nnf gates
        if (values.q_nnf == 1) {
            bool f0 = values.q_o == 1 && (values.q_4 == 1 || values.q_m == 1);
            bool f1 = values.q_r == 1 && (values.q_o == 1 || values.q_4 == 1 || values.q_m == 1);
            if (f0 && f1) {
                result = result && check_relation<NonNativeField>(values, params);
                if (!result) {
                    return report_fail("Failed NonNativeField relation at row idx = ", idx);
                }
            }
        }
#endif
        result = result && check_lookup(values, lookup_hash_table);
        if (!result) {
            return report_fail("Failed Lookup check relation at row idx = ", idx);
        }
        if constexpr (!IsMegaBuilder<Builder>) {
            // Mega covers all internal rounds via the compressed block; there is no
            // q_poseidon2_internal selector in MegaFlavor.
            result = result && check_relation<PoseidonInternal>(values, params);
            if (!result) {
                return report_fail("Failed PoseidonInternal relation at row idx = ", idx);
            }
        }
        result = result && check_relation<PoseidonExternal>(values, params);
        if (!result) {
            return report_fail("Failed PoseidonExternal relation at row idx = ", idx);
        }
 
        if constexpr (IsMegaBuilder<Builder>) {
            result = result && check_relation<PoseidonInitialExternal>(values, params);
            if (!result) {
                return report_fail("Failed PoseidonInitialExternal relation at row idx = ", idx);
            }
            result = result && check_relation<PoseidonQuadInternal>(values, params);
            if (!result) {
                return report_fail("Failed PoseidonQuadInternal relation at row idx = ", idx);
            }
            result = result && check_relation<PoseidonQuadInternalTerminal>(values, params);
            if (!result) {
                return report_fail("Failed PoseidonQuadInternalTerminal relation at row idx = ", idx);
            }
            result = result && check_relation<PoseidonTransitionEntry>(values, params);
            if (!result) {
                return report_fail("Failed PoseidonTransitionEntry relation at row idx = ", idx);
            }
            result = result && check_databus_read(values, builder);
            if (!result) {
                return report_fail("Failed databus read at row idx = ", idx);
            }
            // Note: EccOpQueueRelation is not checked here because it simply establishes that the ecc_op_wire
            // polynomials contain copies of the conventional wire data in the ecc_op region (and are zero elsewhere) so
            // there is nothing to check at the level of the builder.
        }
        if (!result) {
            return report_fail("Failed at row idx = ", idx);
        }
    }
 
    return result;
};
 
template <typename Relation> bool UltraCircuitChecker::check_relation(auto& values, auto& params)
{
    // Define zero initialized array to store the evaluation of each sub-relation
    using SubrelationEvaluations = typename Relation::SumcheckArrayOfValuesOverSubrelations;
    SubrelationEvaluations subrelation_evaluations;
    for (auto& eval : subrelation_evaluations) {
        eval = 0;
    }
 
    // Evaluate each subrelation in the relation
    Relation::accumulate(subrelation_evaluations, values, params, /*scaling_factor=*/1);
 
    // Ensure each subrelation evaluates to zero
    for (auto& eval : subrelation_evaluations) {
        if (eval != 0) {
            return false;
        }
    }
    return true;
}
 
bool UltraCircuitChecker::check_lookup(auto& values, auto& lookup_hash_table)
{
    // If this is a lookup gate, check the inputs are in the hash table containing all table entries
    if (!values.q_lookup.is_zero()) {
        return lookup_hash_table.contains({ values.w_l + values.q_r * values.w_l_shift,
                                            values.w_r + values.q_m * values.w_r_shift,
                                            values.w_o + values.q_c * values.w_o_shift,
                                            values.q_o });
    }
    return true;
};
 
template <typename Builder> bool UltraCircuitChecker::check_databus_read(auto& values, Builder& builder)
{
    if (!values.q_busread.is_zero()) {
        // Extract the {index, value} pair from the read gate inputs
        auto raw_read_idx = static_cast<size_t>(uint256_t(values.w_r));
        auto value = values.w_l;
 
        // Map bus_idx → wire-linear selector on the values struct (mirrors BusData<i>::selector in the relation).
        const std::array<const FF*, NUM_BUS_COLUMNS> bus_selectors{
            &values.q_l, &values.q_r, &values.q_o, &values.q_4, &values.q_m
        };
 
        // Locate the bus column being read (exactly one selector should be active on a busread row) and look up the
        // expected value from the builder's bus vector.
        FF bus_value{};
        bool read_matched = false;
        for (size_t bus_idx = 0; bus_idx < NUM_BUS_COLUMNS; ++bus_idx) {
            if (*bus_selectors[bus_idx] == 1) {
                const auto& bus_vec = builder.get_bus_vector(bus_idx);
                bus_value = builder.get_variable(bus_vec[raw_read_idx]);
                read_matched = true;
            }
        }
        BB_ASSERT(read_matched);
        return (value == bus_value);
    }
    return true;
};
 
bool UltraCircuitChecker::check_tag_data(const TagCheckData& tag_data)
{
    return tag_data.left_product == tag_data.right_product;
};
 
template <typename Builder>
void UltraCircuitChecker::populate_values(
    Builder& builder, auto& block, auto& values, TagCheckData& tag_data, MemoryCheckData& memory_data, size_t idx)
{
    // Function to quickly update tag products and encountered variable set by index and value
    auto update_tag_check_data = [&](const size_t variable_index, const FF& value) {
        size_t real_index = builder.real_variable_index[variable_index];
        // Check to ensure that we are not including a variable twice
        if (tag_data.encountered_variables.contains(real_index)) {
            return;
        }
        uint32_t tag_in = builder.real_variable_tags[real_index];
        if (tag_in != DEFAULT_TAG) {
            uint32_t tag_out = builder.tau().at(tag_in);
            tag_data.left_product *= value + tag_data.gamma * FF(tag_in);
            tag_data.right_product *= value + tag_data.gamma * FF(tag_out);
            tag_data.encountered_variables.insert(real_index);
        }
    };
 
    // A lambda function for computing a memory record term of the form w3 * eta_three + w2 * eta_two + w1 * eta
    auto compute_memory_record_term =
        [](const FF& w_1, const FF& w_2, const FF& w_3, const FF& eta, const FF& eta_two, FF& eta_three) {
            return (w_3 * eta_three + w_2 * eta_two + w_1 * eta);
        };
 
    // Set wire values. Wire 4 is treated specially since it may contain memory records
    values.w_l = builder.get_variable(block.w_l()[idx]);
    values.w_r = builder.get_variable(block.w_r()[idx]);
    values.w_o = builder.get_variable(block.w_o()[idx]);
    // Note: memory_data contains indices into the block to which RAM/ROM gates were added so we need to check that
    // we are indexing into the correct block before updating the w_4 value.
    const bool is_ram_rom_block = (&block == &builder.blocks.memory);
    if (is_ram_rom_block && memory_data.read_record_gates.contains(idx)) {
        values.w_4 = compute_memory_record_term(
            values.w_l, values.w_r, values.w_o, memory_data.eta, memory_data.eta_two, memory_data.eta_three);
    } else if (is_ram_rom_block && memory_data.write_record_gates.contains(idx)) {
        values.w_4 =
            compute_memory_record_term(
                values.w_l, values.w_r, values.w_o, memory_data.eta, memory_data.eta_two, memory_data.eta_three) +
            FF::one();
    } else {
        values.w_4 = builder.get_variable(block.w_4()[idx]);
    }
 
    // Set shifted wire values. Again, wire 4 is treated specially. On final row, set shift values to zero
    if (idx < block.size() - 1) {
        values.w_l_shift = builder.get_variable(block.w_l()[idx + 1]);
        values.w_r_shift = builder.get_variable(block.w_r()[idx + 1]);
        values.w_o_shift = builder.get_variable(block.w_o()[idx + 1]);
        if (is_ram_rom_block && memory_data.read_record_gates.contains(idx + 1)) {
            values.w_4_shift = compute_memory_record_term(values.w_l_shift,
                                                          values.w_r_shift,
                                                          values.w_o_shift,
                                                          memory_data.eta,
                                                          memory_data.eta_two,
                                                          memory_data.eta_three);
        } else if (is_ram_rom_block && memory_data.write_record_gates.contains(idx + 1)) {
            values.w_4_shift = compute_memory_record_term(values.w_l_shift,
                                                          values.w_r_shift,
                                                          values.w_o_shift,
                                                          memory_data.eta,
                                                          memory_data.eta_two,
                                                          memory_data.eta_three) +
                               FF::one();
        } else {
            values.w_4_shift = builder.get_variable(block.w_4()[idx + 1]);
        }
    } else {
        values.w_l_shift = 0;
        values.w_r_shift = 0;
        values.w_o_shift = 0;
        values.w_4_shift = 0;
    }
 
    // Update tag check data
    update_tag_check_data(block.w_l()[idx], values.w_l);
    update_tag_check_data(block.w_r()[idx], values.w_r);
    update_tag_check_data(block.w_o()[idx], values.w_o);
    update_tag_check_data(block.w_4()[idx], values.w_4);
 
    // Set selector values
    values.q_m = block.q_m()[idx];
    values.q_c = block.q_c()[idx];
    values.q_l = block.q_1()[idx];
    values.q_r = block.q_2()[idx];
    values.q_o = block.q_3()[idx];
    values.q_4 = block.q_4()[idx];
    values.q_arith = read_gate_selector(block, GateKind::Arith, idx);
    values.q_delta_range = read_gate_selector(block, GateKind::DeltaRange, idx);
    values.q_elliptic = read_gate_selector(block, GateKind::Elliptic, idx);
    values.q_memory = read_gate_selector(block, GateKind::Memory, idx);
    values.q_nnf = read_gate_selector(block, GateKind::Nnf, idx);
    values.q_lookup = read_gate_selector(block, GateKind::Lookup, idx);
    values.q_poseidon2_external = read_gate_selector(block, GateKind::Poseidon2Ext, idx);
    if constexpr (IsMegaBuilder<Builder>) {
        values.q_5 = block.q_5()[idx];
        values.q_poseidon2_external_initial = read_gate_selector(block, GateKind::Poseidon2ExtInitial, idx);
        values.q_poseidon2_quad_internal = read_gate_selector(block, GateKind::Poseidon2QuadInt, idx);
        values.q_poseidon2_quad_internal_terminal = read_gate_selector(block, GateKind::Poseidon2QuadIntTerminal, idx);
        values.q_poseidon2_transition_entry = read_gate_selector(block, GateKind::Poseidon2TransitionEntry, idx);
        values.q_busread = read_gate_selector(block, GateKind::BusRead, idx);
    } else {
        values.q_poseidon2_internal = read_gate_selector(block, GateKind::Poseidon2Int, idx);
    }
}
 
#ifdef ULTRA_FUZZ
 
template <typename Builder> bool UltraCircuitChecker::relaxed_check_delta_range_relation(Builder& builder)
{
    std::unordered_map<uint32_t, uint64_t> range_tags;
    for (const auto& list : builder.range_lists) {
        range_tags[list.second.range_tag] = list.first;
    }
 
    // Unprocessed blocks check
    for (uint32_t i = 0; i < builder.real_variable_tags.size(); i++) {
        uint32_t tag = builder.real_variable_tags[i];
        if (tag != 0 && range_tags.contains(tag)) {
            uint256_t range = static_cast<uint256_t>(range_tags[tag]);
            uint256_t value = static_cast<uint256_t>(builder.get_variable(i));
            if (value > range) {
#ifndef FUZZING_DISABLE_WARNINGS
                info("Failed range constraint on variable with index = ", i, ": ", value, " > ", range);
#endif
                return false;
            }
        }
    }
 
    // Processed blocks check
    auto block = builder.blocks.delta_range;
    for (size_t idx = 0; idx < block.size(); idx++) {
        if (block.gate_selector_for(GateKind::DeltaRange)[idx] == 0) {
            continue;
        }
        bb::fr w1 = builder.get_variable(block.w_l()[idx]);
        bb::fr w2 = builder.get_variable(block.w_r()[idx]);
        bb::fr w3 = builder.get_variable(block.w_o()[idx]);
        bb::fr w4 = builder.get_variable(block.w_4()[idx]);
        bb::fr w5 = idx == block.size() - 1 ? builder.get_variable(0) : builder.get_variable(block.w_l()[idx + 1]);
 
        uint256_t delta = static_cast<uint256_t>(w2 - w1);
        if (delta > 3) {
#ifndef FUZZING_DISABLE_WARNINGS
            info("Failed sort constraint relation at row idx = ", idx, " with delta1 = ", delta);
            info(w1 - w2);
#endif
            return false;
        }
        delta = static_cast<uint256_t>(w3 - w2);
        if (delta > 3) {
#ifndef FUZZING_DISABLE_WARNINGS
            info("Failed sort constraint relation at row idx = ", idx, " with delta2 = ", delta);
#endif
            return false;
        }
        delta = static_cast<uint256_t>(w4 - w3);
        if (delta > 3) {
#ifndef FUZZING_DISABLE_WARNINGS
            info("Failed sort constraint at row idx = ", idx, " with delta3 = ", delta);
#endif
            return false;
        }
        delta = static_cast<uint256_t>(w5 - w4);
        if (delta > 3) {
#ifndef FUZZING_DISABLE_WARNINGS
            info("Failed sort constraint at row idx = ", idx, " with delta4 = ", delta);
#endif
            return false;
        }
    }
    return true;
}
 
template <typename Builder> bool UltraCircuitChecker::relaxed_check_memory_relation(Builder& builder)
{
    for (size_t i = 0; i < builder.rom_ram_logic.rom_arrays.size(); i++) {
        auto rom_array = builder.rom_ram_logic.rom_arrays[i];
 
        // check set and read ROM records
        for (auto& rr : rom_array.records) {
            uint32_t value_witness_1 = rr.value_column1_witness;
            uint32_t value_witness_2 = rr.value_column2_witness;
            uint32_t index = static_cast<uint32_t>(builder.get_variable(rr.index_witness));
 
            uint32_t table_witness_1 = rom_array.state[index][0];
            uint32_t table_witness_2 = rom_array.state[index][1];
 
            if (builder.get_variable(value_witness_1) != builder.get_variable(table_witness_1)) {
#ifndef FUZZING_DISABLE_WARNINGS
                info("Failed SET/Read ROM[0] in table = ", i, " at idx = ", index);
#endif
                return false;
            }
            if (builder.get_variable(value_witness_2) != builder.get_variable(table_witness_2)) {
#ifndef FUZZING_DISABLE_WARNINGS
                info("Failed SET/Read ROM[1] in table = ", i, " at idx = ", index);
#endif
                return false;
            }
        }
    }
 
    for (size_t i = 0; i < builder.rom_ram_logic.ram_arrays.size(); i++) {
        auto ram_array = builder.rom_ram_logic.ram_arrays[i];
 
        std::vector<uint32_t> tmp_state(ram_array.state.size());
 
        // Simulate the memory call trace
        for (auto& rr : ram_array.records) {
            uint32_t index = static_cast<uint32_t>(builder.get_variable(rr.index_witness));
            uint32_t value_witness = rr.value_witness;
            auto access_type = rr.access_type;
 
            uint32_t table_witness = tmp_state[index];
 
            switch (access_type) {
            case bb::RamRecord::AccessType::READ:
                if (builder.get_variable(value_witness) != builder.get_variable(table_witness)) {
#ifndef FUZZING_DISABLE_WARNINGS
                    info("Failed RAM read in table = ", i, " at idx = ", index);
#endif
                    return false;
                }
                break;
            case bb::RamRecord::AccessType::WRITE:
                tmp_state[index] = value_witness;
                break;
            default:
                return false;
            }
        }
 
        if (tmp_state != ram_array.state) {
#ifndef FUZZING_DISABLE_WARNINGS
            info("Failed RAM final state check at table = ", i);
#endif
            return false;
        }
    }
    return true;
}
#endif
 
// Template method instantiations for each check method
template bool UltraCircuitChecker::check<UltraCircuitBuilder_<UltraExecutionTraceBlocks>>(
    const UltraCircuitBuilder_<UltraExecutionTraceBlocks>& builder_in);
template bool UltraCircuitChecker::check<MegaCircuitBuilder_<bb::fr>>(const MegaCircuitBuilder_<bb::fr>& builder_in);
} // namespace bb