honk_recursion_constraint.test.cpp

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#include "honk_recursion_constraint.hpp"
#include "acir_format.hpp"
#include "barretenberg/chonk/mock_circuit_producer.hpp"
#include "barretenberg/dsl/acir_format/gate_count_constants.hpp"
#include "barretenberg/dsl/acir_format/test_class_predicate.hpp"
#include "barretenberg/dsl/acir_format/utils.hpp"
#include "barretenberg/dsl/acir_format/witness_constant.hpp"
#include "barretenberg/numeric/uint256/uint256.hpp"
#include "barretenberg/special_public_inputs/special_public_inputs.hpp"
#include "barretenberg/ultra_honk/prover_instance.hpp"
#include "barretenberg/ultra_honk/ultra_prover.hpp"
#include "barretenberg/ultra_honk/ultra_verifier.hpp"
 
#include <gtest/gtest.h>
#include <vector>
 
using namespace acir_format;
using namespace bb;
 
template <typename RecursiveFlavor_, bool IsRootRollup_, size_t N_, std::array<size_t, N_> LayerSizes_>
class HonkRecursionTestParams {
  public:
    using RecursiveFlavor = RecursiveFlavor_;
    static constexpr bool IsRootRollup = IsRootRollup_;
    static constexpr size_t N = N_;
    static constexpr std::array<size_t, N> LayerSizes = LayerSizes_;
};
 
template <typename RecursiveFlavor, bool IsRootRollup, size_t N, std::array<size_t, N> LayerSizes>
class HonkRecursionConstraintTestingFunctions {
  public:
    // Check that the array in the template parameter is in increasing order
    static_assert([]() {
        for (size_t idx = 0; idx < N - 1; idx++) {
            if (LayerSizes[idx + 1] > LayerSizes[idx]) {
                return false;
            }
        }
 
        return true;
    }());
 
    // Check that if IsRootRollup is true, then we set the parameters correctly
    static_assert([]() {
        if constexpr (IsRootRollup) {
            // Root rollup requires N == 1 && LayerSizes[0] == 2 for 2 recursive verifications
            return N == 1 && LayerSizes[0] == 2;
        }
 
        return true;
    }());
 
    using InnerFlavor = RecursiveFlavor::NativeFlavor;
    using InnerBuilder = InnerFlavor::CircuitBuilder;
    // For rollup tests, we use RollupIO; otherwise we use DefaultIO
    static constexpr bool UseRollupIO = IsRootRollup;
    using InnerIO = std::conditional_t<UseRollupIO,
                                       bb::stdlib::recursion::honk::RollupIO,
                                       bb::stdlib::recursion::honk::DefaultIO<InnerBuilder>>;
    using InnerProverInstance = ProverInstance_<InnerFlavor>;
    using InnerVerificationKey = InnerFlavor::VerificationKey;
    using InnerProver = UltraProver_<InnerFlavor>;
 
    // Determine the proof type of the "inner" circuits, i.e., the ones up to the level below the top. The proof type is
    // determined by the flavor with which we prove the circuits.
    static constexpr uint32_t InnerProofType = []() {
        if constexpr (UseRollupIO) {
            return ROLLUP_HONK;
        } else if constexpr (InnerFlavor::HasZK) {
            return HONK_ZK;
        }
 
        return HONK;
    }();
 
    static constexpr bool IS_SINGLE_RECURSIVE_VERIFICATION = N == 1 && LayerSizes[0] == 1;
    using AcirConstraint =
        std::conditional_t<IS_SINGLE_RECURSIVE_VERIFICATION, RecursionConstraint, std::vector<RecursionConstraint>>;
    using Builder = RecursiveFlavor::CircuitBuilder;
 
    // All the circuits have the same number of public inputs, this tests the slicing of public inputs from the proof at
    // every level
    static constexpr size_t NUM_PUBLIC_INPUTS = 2;
 
    struct InvalidWitness {
      public:
        enum class Target : uint8_t { None, VKHash, VK, Proof };
 
        static std::vector<Target> get_all()
        {
            if constexpr (IsRootRollup) {
                // Only one for Root because it is very heavy
                return { Target::VKHash };
            }
            return { Target::None, Target::VKHash, Target::VK, Target::Proof };
        }
 
        static std::vector<std::string> get_labels()
        {
            if constexpr (IsRootRollup) {
                // Only one for Root because it is very heavy
                return { "VKHash" };
            }
            return { "None", "VKHash", "VK", "Proof" };
        }
    };
 
    static InnerBuilder create_inner_circuit()
    {
        InnerBuilder builder;
 
        MockCircuits::add_arithmetic_gates(builder);
        MockCircuits::add_lookup_gates(builder);
 
        for (size_t idx = 0; idx < NUM_PUBLIC_INPUTS; idx++) {
            builder.add_public_variable(InnerBuilder::FF::random_element());
        }
        InnerIO::add_default(builder);
 
        return builder;
    }
 
    static AcirConstraint merge_recursion_constraints(std::vector<RecursionConstraint>& constraints,
                                                      std::vector<WitnessVector>& witness_vectors,
                                                      WitnessVector& witness_values)
    {
        // Lambda to offset the recursion constraint by the current size of the witness vector
        auto offset_recursion_constraint = [](RecursionConstraint& honk_recursion_constraint, const size_t offset) {
            uint32_t uint32_offset = static_cast<uint32_t>(offset);
            auto shift_by_offset = [&uint32_offset](std::vector<uint32_t>& indices) {
                for (auto& index : indices) {
                    index += uint32_offset;
                }
            };
 
            shift_by_offset(honk_recursion_constraint.key);
            shift_by_offset(honk_recursion_constraint.proof);
            shift_by_offset(honk_recursion_constraint.public_inputs);
            honk_recursion_constraint.key_hash += uint32_offset;
            honk_recursion_constraint.predicate.index += uint32_offset;
        };
 
        for (auto [constraint, witnesses] : zip_view(constraints, witness_vectors)) {
            offset_recursion_constraint(constraint, witness_values.size());
            // If this is the root rollup, we need to set the proof type to ROOT_ROLLUP_HONK
            constraint.proof_type = IsRootRollup ? static_cast<uint32_t>(ROOT_ROLLUP_HONK) : constraint.proof_type;
            witness_values.insert(witness_values.end(), witnesses.begin(), witnesses.end());
        }
 
        if constexpr (IS_SINGLE_RECURSIVE_VERIFICATION) {
            return constraints[0];
        } else {
            return constraints;
        }
    }
 
    static std::pair<RecursionConstraint, WitnessVector> circuit_to_recursion_constraint(InnerBuilder& builder)
    {
        // Add public inputs if needed
        for (size_t idx = builder.num_public_inputs(); idx < NUM_PUBLIC_INPUTS; idx++) {
            builder.add_public_variable(InnerBuilder::FF::random_element());
        }
        auto prover_instance = std::make_shared<InnerProverInstance>(builder);
        auto verification_key = std::make_shared<InnerVerificationKey>(prover_instance->get_precomputed());
 
        InnerProver prover(prover_instance, verification_key);
        auto proof = prover.construct_proof();
 
        WitnessVector witness_values;
        RecursionConstraint recursion_constraint =
            recursion_data_to_recursion_constraint(witness_values,
                                                   proof,
                                                   verification_key->to_field_elements(),
                                                   verification_key->hash(),
                                                   bb::fr::one(),
                                                   builder.num_public_inputs() - InnerIO::PUBLIC_INPUTS_SIZE,
                                                   InnerProofType);
 
        return { recursion_constraint, witness_values };
    }
 
    static ProgramMetadata generate_metadata()
    {
        // The outer circuit has IPA claims if using rollup IO and not the root rollup (which finalizes IPA)
        return ProgramMetadata{ .has_ipa_claim = UseRollupIO && !IsRootRollup };
    }
 
    static std::pair<AcirConstraint, WitnessVector> invalidate_witness(
        AcirConstraint honk_recursion_constraints,
        WitnessVector witness_values,
        const InvalidWitness::Target& invalid_witness_target)
    {
        switch (invalid_witness_target) {
        case InvalidWitness::Target::None:
            break;
        case InvalidWitness::Target::VKHash: {
            // Invalidate the circuit by modifying the vk hash
            if constexpr (IS_SINGLE_RECURSIVE_VERIFICATION) {
                witness_values[honk_recursion_constraints.key_hash] += fr::one();
            } else {
                witness_values[honk_recursion_constraints[0].key_hash] += fr::one();
            }
            break;
        }
        case InvalidWitness::Target::VK: {
            // Invalidate the circuit by modifying the first element of the vk (log circuit size)
            std::vector<uint32_t> vk_indices;
            if constexpr (IS_SINGLE_RECURSIVE_VERIFICATION) {
                witness_values[honk_recursion_constraints.key[0]] += fr::one();
            } else {
                witness_values[honk_recursion_constraints[0].key[0]] += fr::one();
            }
            break;
        }
        case InvalidWitness::Target::Proof: {
            // Invalidate the circuit by modifying the first element of the proof after the public inputs, which is a
            // group element (vk commitment)
            std::vector<uint32_t> proof_indices;
            if constexpr (IS_SINGLE_RECURSIVE_VERIFICATION) {
                proof_indices = honk_recursion_constraints.proof;
            } else {
                proof_indices = honk_recursion_constraints[0].proof;
            }
            size_t commitment_size = FrCodec::template calc_num_fields<typename InnerFlavor::Commitment>();
            std::vector<bb::fr> mock_proof_element = FrCodec::serialize_to_fields(InnerFlavor::Commitment::one());
            for (size_t idx = 0; idx < commitment_size; idx++) {
                witness_values[proof_indices[InnerIO::PUBLIC_INPUTS_SIZE + idx]] = mock_proof_element[idx];
            }
            break;
        }
        }
 
        return { honk_recursion_constraints, witness_values };
    }
 
    static void generate_constraints(AcirConstraint& honk_recursion_constraint, WitnessVector& witness_values)
    {
        std::vector<RecursionConstraint> constraints;
        std::vector<WitnessVector> witness_vectors;
 
        for (size_t layer_idx = 0; layer_idx < N; layer_idx++) {
            size_t current_layer_size = LayerSizes[layer_idx];
            for (size_t idx = 0; idx < current_layer_size; idx++) {
                if (layer_idx == 0) {
                    // If we are at the bottom layer, we create the circuit and then create the recursion constraint
                    // that verifies the circuit
                    auto [constraint, witnesses] = []() {
                        InnerBuilder builder = create_inner_circuit();
                        return circuit_to_recursion_constraint(builder);
                    }();
                    constraints.emplace_back(std::move(constraint));
                    witness_vectors.emplace_back(std::move(witnesses));
                } else {
                    // If we are in a layer above the bottom one, we take the recursion constraints at index idx and
                    // build a circuit the recursively verifies these recursion constraints
                    RecursionConstraint recursion_constraint = constraints[idx];
                    WitnessVector witnesses = witness_vectors[idx];
 
                    AcirFormat acir_format = constraint_to_acir_format(recursion_constraint);
 
                    AcirProgram acir_program{ .constraints = acir_format, .witness = witnesses };
 
                    std::tie(constraints[idx], witness_vectors[idx]) = [&]() {
                        auto builder = create_circuit<InnerBuilder>(acir_program, generate_metadata());
                        return circuit_to_recursion_constraint(builder);
                    }();
                }
            }
        }
 
        // Merge the constraints by offsetting the relevant indices and concatenating the witness vectors
        honk_recursion_constraint = merge_recursion_constraints(constraints, witness_vectors, witness_values);
    }
};
 
template <typename Params>
class HonkRecursionConstraintTestWithPredicate
    : public ::testing::Test,
      public TestClassWithPredicate<HonkRecursionConstraintTestingFunctions<typename Params::RecursiveFlavor,
                                                                            Params::IsRootRollup,
                                                                            Params::N,
                                                                            Params::LayerSizes>> {
  public:
    using RecursiveFlavor = Params::RecursiveFlavor;
    static constexpr bool IsRootRollup = Params::IsRootRollup;
 
  protected:
    static void SetUpTestSuite() { bb::srs::init_file_crs_factory(bb::srs::bb_crs_path()); }
};
 
// We test the predicate with vanilla recursion. This is enough as the predicate logic is a standalone component,
// there's no inter-constraint interaction due to the existence or the value of the predicate.
using HonkRecursionTypesWithPredicate =
    testing::Types<HonkRecursionTestParams<UltraRecursiveFlavor_<UltraCircuitBuilder>, false, 1, { 1 }>,
                   HonkRecursionTestParams<UltraZKRecursiveFlavor_<UltraCircuitBuilder>, false, 1, { 1 }>,
                   HonkRecursionTestParams<UltraRecursiveFlavor_<MegaCircuitBuilder>, false, 1, { 1 }>,
                   HonkRecursionTestParams<UltraZKRecursiveFlavor_<MegaCircuitBuilder>, false, 1, { 1 }>>;
 
TYPED_TEST_SUITE(HonkRecursionConstraintTestWithPredicate, HonkRecursionTypesWithPredicate);
 
TYPED_TEST(HonkRecursionConstraintTestWithPredicate, GenerateVKFromConstraints)
{
    // The flavor with which we prove the outer circuit (the one verifying F_1, .., F_{s_1}) depends on what type of
    // data the inner circuits have propagated and the builder.
    using Flavor = std::conditional_t<IsMegaBuilder<typename TestFixture::Builder>,
                                      MegaFlavor,
                                      typename TestFixture::RecursiveFlavor::NativeFlavor>;
    TestFixture::template test_vk_independence<Flavor>();
}
 
TYPED_TEST(HonkRecursionConstraintTestWithPredicate, ConstantTrue)
{
    BB_DISABLE_ASSERTS();
    TestFixture::test_constant_true(TestFixture::InvalidWitnessTarget::VKHash);
}
 
TYPED_TEST(HonkRecursionConstraintTestWithPredicate, WitnessTrue)
{
    BB_DISABLE_ASSERTS();
    TestFixture::test_witness_true(TestFixture::InvalidWitnessTarget::VKHash);
}
 
TYPED_TEST(HonkRecursionConstraintTestWithPredicate, WitnessFalseSlow)
{
    BB_DISABLE_ASSERTS();
    TestFixture::test_witness_false_slow();
}
 
TYPED_TEST(HonkRecursionConstraintTestWithPredicate, GateCountSingleHonkRecursion)
{
    using RecursiveFlavor = TestFixture::RecursiveFlavor;
    using Builder = TestFixture::Builder;
    using InvalidWitnessTarget = TestFixture::InvalidWitnessTarget;
 
    typename TestFixture::AcirConstraint constraint;
    WitnessVector witness_values;
    TestFixture::Base::generate_constraints(constraint, witness_values);
 
    for (const auto predicate_mode : Predicate<InvalidWitnessTarget>::get_all()) {
        Predicate<InvalidWitnessTarget> predicate{ .test_case = predicate_mode,
                                                   .invalid_witness = InvalidWitnessTarget::None };
        auto [updated_constraint, updated_witness_values] =
            TestFixture::update_witness_based_on_predicate(constraint, witness_values, predicate);
 
        AcirFormat constraint_system = constraint_to_acir_format(updated_constraint);
 
        AcirProgram program{ constraint_system, updated_witness_values };
        ProgramMetadata metadata = TestFixture::Base::generate_metadata();
        metadata.collect_gates_per_opcode = true;
        auto builder = create_circuit<Builder>(program, metadata);
 
        // Verify the gate count was recorded
        EXPECT_EQ(program.constraints.gates_per_opcode.size(), 1);
 
        // Get expected values based on predicate mode
        auto [EXPECTED_GATE_COUNT, EXPECTED_ULTRA_OPS] = HONK_RECURSION_CONSTANTS<RecursiveFlavor>(predicate_mode);
 
        // Assert gate count
        EXPECT_EQ(program.constraints.gates_per_opcode[0], EXPECTED_GATE_COUNT);
 
        // For MegaBuilder, also assert ultra ops count
        if constexpr (IsMegaBuilder<Builder>) {
            size_t actual_ultra_ops = builder.op_queue->get_current_subtable_size();
            EXPECT_EQ(actual_ultra_ops, EXPECTED_ULTRA_OPS);
        }
    }
}
 
template <typename Params>
class HonkRecursionConstraintTestWithoutPredicate
    : public ::testing::Test,
      public TestClass<HonkRecursionConstraintTestingFunctions<typename Params::RecursiveFlavor,
                                                               Params::IsRootRollup,
                                                               Params::N,
                                                               Params::LayerSizes>> {
  public:
    using RecursiveFlavor = Params::RecursiveFlavor;
    static constexpr bool IsRootRollup = Params::IsRootRollup;
 
  protected:
    static void SetUpTestSuite() { bb::srs::init_file_crs_factory(bb::srs::bb_crs_path()); }
};
 
using HonkRecursionTypesWithoutPredicate = testing::Types<
    HonkRecursionTestParams<UltraRecursiveFlavor_<UltraCircuitBuilder>, false, 1, { 2 }>,      // Merge circuit
    HonkRecursionTestParams<UltraZKRecursiveFlavor_<UltraCircuitBuilder>, false, 1, { 2 }>,    // Merge circuit
    HonkRecursionTestParams<UltraRecursiveFlavor_<UltraCircuitBuilder>, true, 1, { 2 }>,       // Root rollup circuit
    HonkRecursionTestParams<UltraZKRecursiveFlavor_<UltraCircuitBuilder>, false, 2, { 2, 1 }>, // Double recursion
    HonkRecursionTestParams<UltraZKRecursiveFlavor_<UltraCircuitBuilder>, false, 2, { 2, 2 }>, // Merge two circuits
    HonkRecursionTestParams<UltraRecursiveFlavor_<MegaCircuitBuilder>, false, 4, { 4, 3, 1, 1 }>>; // Complex flow
 
TYPED_TEST_SUITE(HonkRecursionConstraintTestWithoutPredicate, HonkRecursionTypesWithoutPredicate);
 
TYPED_TEST(HonkRecursionConstraintTestWithoutPredicate, GenerateVKFromConstraints)
{
    if constexpr (TypeParam::IsRootRollup) {
        TestFixture::template test_vk_independence<UltraZKFlavor>();
    } else {
        // The flavor with which we prove the outer circuit (the one verifying F_1, .., F_{s_1}) depends on what type of
        // data the inner circuits have propagated and the builder.
        using Flavor = std::conditional_t<IsMegaBuilder<typename TestFixture::Builder>,
                                          MegaFlavor,
                                          typename TestFixture::RecursiveFlavor::NativeFlavor>;
 
        TestFixture::template test_vk_independence<Flavor>();
    }
}
 
TYPED_TEST(HonkRecursionConstraintTestWithoutPredicate, Tampering)
{
    BB_DISABLE_ASSERTS();
    [[maybe_unused]] std::vector<std::string> _ = TestFixture::test_tampering();
}
 
TYPED_TEST(HonkRecursionConstraintTestWithoutPredicate, GateCountRootRollup)
{
    using Builder = TestFixture::Builder;
 
    if constexpr (!TestFixture::IsRootRollup) {
        GTEST_SKIP(); // We have already pinned the gate counts in this situation
    }
 
    typename TestFixture::AcirConstraint constraint;
    WitnessVector witness_values;
    TestFixture::Base::generate_constraints(constraint, witness_values);
 
    AcirFormat constraint_system = constraint_to_acir_format(constraint);
 
    AcirProgram program{ constraint_system, witness_values };
    ProgramMetadata metadata = TestFixture::Base::generate_metadata();
    metadata.collect_gates_per_opcode = true;
    auto builder = create_circuit<Builder>(program, metadata);
 
    // Verify the gate count was recorded
    EXPECT_EQ(program.constraints.gates_per_opcode.size(), 2);
 
    // Assert gate count
    EXPECT_EQ(builder.get_num_finalized_gates_inefficient(), ROOT_ROLLUP_GATE_COUNT);
}