feat: add miscellaneous block to handle structure trace overflow (#9733)

Adds an `overflow` block to the set of execution trace blocks which can
store arbitrary gate types that have "overflowed" the capacity of their
corresponding designated gate type block. This allows for accumulation
of app circuits which do not fit into a given structured trace
configuration.

It works as follows: when constructing a circuit, there is no bound on
the size of each gate block. When a proving key is constructed, we check
the capacity of each block and move any overflow into the overflow
block. In all cases, the polynomials have the prescribed trace structure
at the beginning plus a possible overflow block at the end.

---------

Co-authored-by: iakovenkos <sergey.s.yakovenko@gmail.com>

barretenberg/cpp/src/barretenberg/bb/main.cpp

@@ -359,7 +359,7 @@ void client_ivc_prove_output_all_msgpack(const std::string& bytecodePath,
     // TODO(https://github.com/AztecProtocol/barretenberg/issues/1101): remove use of auto_verify_mode
     ClientIVC ivc;
     ivc.auto_verify_mode = true;
-    ivc.trace_structure = TraceStructure::E2E_FULL_TEST;
+    ivc.trace_settings.structure = TraceStructure::E2E_FULL_TEST;
 
     // Accumulate the entire program stack into the IVC
     // TODO(https://github.com/AztecProtocol/barretenberg/issues/1116): remove manual setting of is_kernel once databus
@@ -448,7 +448,7 @@ bool foldAndVerifyProgram(const std::string& bytecodePath, const std::string& wi
 
     ClientIVC ivc;
     ivc.auto_verify_mode = true;
-    ivc.trace_structure = TraceStructure::SMALL_TEST;
+    ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
     auto program_stack = acir_format::get_acir_program_stack(
         bytecodePath, witnessPath, false); // TODO(https://github.com/AztecProtocol/barretenberg/issues/1013): this
@@ -501,7 +501,7 @@ void client_ivc_prove_output_all(const std::string& bytecodePath,
     // TODO(https://github.com/AztecProtocol/barretenberg/issues/1101): remove use of auto_verify_mode
     ClientIVC ivc;
     ivc.auto_verify_mode = true;
-    ivc.trace_structure = TraceStructure::E2E_FULL_TEST;
+    ivc.trace_settings.structure = TraceStructure::E2E_FULL_TEST;
 
     auto program_stack = acir_format::get_acir_program_stack(
         bytecodePath, witnessPath, false); // TODO(https://github.com/AztecProtocol/barretenberg/issues/1013): this

barretenberg/cpp/src/barretenberg/benchmark/client_ivc_bench/client_ivc.bench.cpp

@@ -34,7 +34,7 @@ class ClientIVCBench : public benchmark::Fixture {
 BENCHMARK_DEFINE_F(ClientIVCBench, Full)(benchmark::State& state)
 {
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::CLIENT_IVC_BENCH;
+    ivc.trace_settings.structure = TraceStructure::CLIENT_IVC_BENCH;
     auto total_num_circuits = 2 * static_cast<size_t>(state.range(0)); // 2x accounts for kernel circuits
     auto mocked_vkeys = mock_verification_keys(total_num_circuits);
 

barretenberg/cpp/src/barretenberg/client_ivc/client_ivc.cpp

@@ -173,11 +173,11 @@ void ClientIVC::accumulate(ClientCircuit& circuit, const std::shared_ptr<Verific
     // Construct the proving key for circuit
     std::shared_ptr<DeciderProvingKey> proving_key;
     if (!initialized) {
-        proving_key = std::make_shared<DeciderProvingKey>(circuit, trace_structure);
-        trace_usage_tracker = ExecutionTraceUsageTracker(trace_structure);
+        proving_key = std::make_shared<DeciderProvingKey>(circuit, trace_settings);
+        trace_usage_tracker = ExecutionTraceUsageTracker(trace_settings);
     } else {
         proving_key = std::make_shared<DeciderProvingKey>(
-            circuit, trace_structure, fold_output.accumulator->proving_key.commitment_key);
+            circuit, trace_settings, fold_output.accumulator->proving_key.commitment_key);
     }
 
     vinfo("getting honk vk... precomputed?: ", precomputed_vk);
@@ -382,10 +382,10 @@ std::vector<std::shared_ptr<ClientIVC::VerificationKey>> ClientIVC::precompute_f
     }
 
     // Reset the scheme so it can be reused for actual accumulation, maintaining the trace structure setting as is
-    TraceStructure structure = trace_structure;
+    TraceSettings settings = trace_settings;
     bool auto_verify = auto_verify_mode;
     *this = ClientIVC();
-    this->trace_structure = structure;
+    this->trace_settings = settings;
     this->auto_verify_mode = auto_verify;
 
     return vkeys;

barretenberg/cpp/src/barretenberg/client_ivc/client_ivc.hpp

@@ -115,8 +115,8 @@ class ClientIVC {
     // Management of linking databus commitments between circuits in the IVC
     DataBusDepot bus_depot;
 
-    // A flag indicating whether or not to construct a structured trace in the DeciderProvingKey
-    TraceStructure trace_structure = TraceStructure::NONE;
+    // Settings related to the use of fixed block sizes for each gate in the execution trace
+    TraceSettings trace_settings;
 
     // TODO(https://github.com/AztecProtocol/barretenberg/issues/1101): eventually do away with this.
     // Setting auto_verify_mode = true will cause kernel completion logic to be added to kernels automatically

barretenberg/cpp/src/barretenberg/client_ivc/client_ivc.test.cpp

@@ -76,11 +76,11 @@ class ClientIVCTests : public ::testing::Test {
         }
 
         auto precompute_verification_keys(const size_t num_circuits,
-                                          TraceStructure trace_structure,
+                                          TraceSettings trace_settings,
                                           size_t log2_num_gates = 16)
         {
             ClientIVC ivc; // temporary IVC instance needed to produce the complete kernel circuits
-            ivc.trace_structure = trace_structure;
+            ivc.trace_settings = trace_settings;
 
             std::vector<std::shared_ptr<VerificationKey>> vkeys;
 
@@ -163,7 +163,7 @@ TEST_F(ClientIVCTests, BadProofFailure)
     // Confirm that the IVC verifies if nothing is tampered with
     {
         ClientIVC ivc;
-        ivc.trace_structure = TraceStructure::SMALL_TEST;
+        ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
         MockCircuitProducer circuit_producer;
 
@@ -179,7 +179,7 @@ TEST_F(ClientIVCTests, BadProofFailure)
     // The IVC throws an exception if the FIRST fold proof is tampered with
     {
         ClientIVC ivc;
-        ivc.trace_structure = TraceStructure::SMALL_TEST;
+        ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
         MockCircuitProducer circuit_producer;
 
@@ -204,7 +204,7 @@ TEST_F(ClientIVCTests, BadProofFailure)
     // The IVC fails if the SECOND fold proof is tampered with
     {
         ClientIVC ivc;
-        ivc.trace_structure = TraceStructure::SMALL_TEST;
+        ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
         MockCircuitProducer circuit_producer;
 
@@ -229,7 +229,7 @@ TEST_F(ClientIVCTests, BadProofFailure)
     // The IVC fails if the 3rd/FINAL fold proof is tampered with
     {
         ClientIVC ivc;
-        ivc.trace_structure = TraceStructure::SMALL_TEST;
+        ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
         MockCircuitProducer circuit_producer;
 
@@ -278,7 +278,7 @@ TEST_F(ClientIVCTests, BasicLarge)
 TEST_F(ClientIVCTests, BasicStructured)
 {
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::SMALL_TEST;
+    ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
     MockCircuitProducer circuit_producer;
 
@@ -307,7 +307,7 @@ TEST_F(ClientIVCTests, PrecomputedVerificationKeys)
 
     MockCircuitProducer circuit_producer;
 
-    auto precomputed_vks = circuit_producer.precompute_verification_keys(NUM_CIRCUITS, TraceStructure::NONE);
+    auto precomputed_vks = circuit_producer.precompute_verification_keys(NUM_CIRCUITS, TraceSettings{});
 
     // Construct and accumulate set of circuits using the precomputed vkeys
     for (size_t idx = 0; idx < NUM_CIRCUITS; ++idx) {
@@ -325,15 +325,15 @@ TEST_F(ClientIVCTests, PrecomputedVerificationKeys)
 TEST_F(ClientIVCTests, StructuredPrecomputedVKs)
 {
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::SMALL_TEST;
+    ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
     size_t NUM_CIRCUITS = 4;
     size_t log2_num_gates = 5; // number of gates in baseline mocked circuit
 
     MockCircuitProducer circuit_producer;
 
     auto precomputed_vks =
-        circuit_producer.precompute_verification_keys(NUM_CIRCUITS, ivc.trace_structure, log2_num_gates);
+        circuit_producer.precompute_verification_keys(NUM_CIRCUITS, ivc.trace_settings, log2_num_gates);
 
     // Construct and accumulate set of circuits using the precomputed vkeys
     for (size_t idx = 0; idx < NUM_CIRCUITS; ++idx) {
@@ -357,10 +357,10 @@ TEST(ClientIVCBenchValidation, Full6)
     bb::srs::init_grumpkin_crs_factory("../srs_db/grumpkin");
 
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::CLIENT_IVC_BENCH;
+    ivc.trace_settings.structure = TraceStructure::CLIENT_IVC_BENCH;
     size_t total_num_circuits{ 12 };
     PrivateFunctionExecutionMockCircuitProducer circuit_producer;
-    auto precomputed_vkeys = circuit_producer.precompute_verification_keys(total_num_circuits, ivc.trace_structure);
+    auto precomputed_vkeys = circuit_producer.precompute_verification_keys(total_num_circuits, ivc.trace_settings);
     perform_ivc_accumulation_rounds(total_num_circuits, ivc, precomputed_vkeys);
     auto proof = ivc.prove();
     bool verified = verify_ivc(proof, ivc);
@@ -377,7 +377,7 @@ TEST(ClientIVCBenchValidation, Full6MockedVKs)
         bb::srs::init_grumpkin_crs_factory("../srs_db/grumpkin");
 
         ClientIVC ivc;
-        ivc.trace_structure = TraceStructure::CLIENT_IVC_BENCH;
+        ivc.trace_settings.structure = TraceStructure::CLIENT_IVC_BENCH;
         size_t total_num_circuits{ 12 };
         PrivateFunctionExecutionMockCircuitProducer circuit_producer;
         auto mocked_vkeys = mock_verification_keys(total_num_circuits);
@@ -386,4 +386,33 @@ TEST(ClientIVCBenchValidation, Full6MockedVKs)
         verify_ivc(proof, ivc);
     };
     ASSERT_NO_FATAL_FAILURE(run_test());
-}
+}
+
+/**
+ * @brief Test use of structured trace overflow block mechanism
+ * @details Accumulate 4 circuits which have progressively more arithmetic gates. The final two overflow the prescribed
+ * arithmetic block size and make use of the overflow block which has sufficient capacity.
+ *
+ */
+TEST_F(ClientIVCTests, StructuredTraceOverflow)
+{
+    ClientIVC ivc;
+
+    // Define trace settings with sufficient overflow capacity to accommodate each of the circuits to be accumulated
+    uint32_t overflow_capacity = 1 << 17;
+    ivc.trace_settings = { TraceStructure::SMALL_TEST, overflow_capacity };
+
+    MockCircuitProducer circuit_producer;
+
+    size_t NUM_CIRCUITS = 4;
+
+    // Construct and accumulate some circuits of varying size
+    size_t log2_num_gates = 14;
+    for (size_t idx = 0; idx < NUM_CIRCUITS; ++idx) {
+        auto circuit = circuit_producer.create_next_circuit(ivc, log2_num_gates);
+        ivc.accumulate(circuit);
+        log2_num_gates += 1;
+    }
+
+    EXPECT_TRUE(ivc.prove_and_verify());
+};

barretenberg/cpp/src/barretenberg/client_ivc/client_ivc_auto_verify.test.cpp

@@ -132,7 +132,7 @@ TEST_F(ClientIVCAutoVerifyTests, BasicStructured)
 {
     ClientIVC ivc;
     ivc.auto_verify_mode = true;
-    ivc.trace_structure = TraceStructure::SMALL_TEST;
+    ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
     // Construct some circuits of varying size
     Builder circuit_0 = create_mock_circuit(ivc, /*is_kernel=*/false, /*log2_num_gates=*/5);
@@ -185,7 +185,7 @@ TEST_F(ClientIVCAutoVerifyTests, StructuredPrecomputedVKs)
 {
     ClientIVC ivc;
     ivc.auto_verify_mode = true;
-    ivc.trace_structure = TraceStructure::SMALL_TEST;
+    ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
     // Construct a set of arbitrary circuits
     size_t NUM_CIRCUITS = 4;

barretenberg/cpp/src/barretenberg/client_ivc/client_ivc_integration.test.cpp

@@ -37,7 +37,7 @@ class ClientIVCIntegrationTests : public ::testing::Test {
 TEST_F(ClientIVCIntegrationTests, BenchmarkCaseSimple)
 {
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::CLIENT_IVC_BENCH;
+    ivc.trace_settings.structure = TraceStructure::CLIENT_IVC_BENCH;
 
     MockCircuitProducer circuit_producer;
 
@@ -61,7 +61,7 @@ TEST_F(ClientIVCIntegrationTests, BenchmarkCaseSimple)
 TEST_F(ClientIVCIntegrationTests, ConsecutiveKernels)
 {
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::CLIENT_IVC_BENCH;
+    ivc.trace_settings.structure = TraceStructure::CLIENT_IVC_BENCH;
 
     MockCircuitProducer circuit_producer;
 
@@ -89,15 +89,15 @@ TEST_F(ClientIVCIntegrationTests, ConsecutiveKernels)
 TEST_F(ClientIVCIntegrationTests, BenchmarkCasePrecomputedVKs)
 {
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::CLIENT_IVC_BENCH;
+    ivc.trace_settings.structure = TraceStructure::CLIENT_IVC_BENCH;
 
     size_t NUM_CIRCUITS = 6;
 
     // Precompute the verification keys for each circuit in the IVC
     std::vector<std::shared_ptr<VerificationKey>> precomputed_vks;
     {
         MockCircuitProducer circuit_producer;
-        precomputed_vks = circuit_producer.precompute_verification_keys(NUM_CIRCUITS, ivc.trace_structure);
+        precomputed_vks = circuit_producer.precompute_verification_keys(NUM_CIRCUITS, ivc.trace_settings);
     }
 
     MockCircuitProducer circuit_producer;
@@ -123,7 +123,7 @@ TEST_F(ClientIVCIntegrationTests, BenchmarkCasePrecomputedVKs)
 TEST_F(ClientIVCIntegrationTests, DatabusFailure)
 {
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::CLIENT_IVC_BENCH;
+    ivc.trace_settings.structure = TraceStructure::CLIENT_IVC_BENCH;
 
     MockCircuitProducer circuit_producer;
 

barretenberg/cpp/src/barretenberg/client_ivc/mock_circuit_producer.hpp

@@ -135,10 +135,10 @@ class PrivateFunctionExecutionMockCircuitProducer {
      * @param trace_structure Trace structuring must be known in advance because it effects the VKs
      * @return set of num_circuits-many verification keys
      */
-    auto precompute_verification_keys(const size_t num_circuits, TraceStructure trace_structure)
+    auto precompute_verification_keys(const size_t num_circuits, TraceSettings trace_settings)
     {
         ClientIVC ivc; // temporary IVC instance needed to produce the complete kernel circuits
-        ivc.trace_structure = trace_structure;
+        ivc.trace_settings = trace_settings;
 
         std::vector<std::shared_ptr<VerificationKey>> vkeys;
 

barretenberg/cpp/src/barretenberg/client_ivc/mock_kernel_pinning.test.cpp

@@ -24,7 +24,7 @@ class MockKernelTest : public ::testing::Test {
 TEST_F(MockKernelTest, PinFoldingKernelSizes)
 {
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::CLIENT_IVC_BENCH;
+    ivc.trace_settings.structure = TraceStructure::CLIENT_IVC_BENCH;
 
     MockCircuitProducer circuit_producer;
 

barretenberg/cpp/src/barretenberg/dsl/acir_format/acir_integration.test.cpp

@@ -402,7 +402,7 @@ TEST_P(AcirIntegrationFoldingTest, DISABLED_FoldAndVerifyProgramStack)
 
     ClientIVC ivc;
     ivc.auto_verify_mode = true;
-    ivc.trace_structure = TraceStructure::SMALL_TEST;
+    ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
     while (!program_stack.empty()) {
         auto program = program_stack.back();

barretenberg/cpp/src/barretenberg/dsl/acir_format/ivc_recursion_constraint.test.cpp

@@ -160,7 +160,7 @@ class IvcRecursionConstraintTest : public ::testing::Test {
 TEST_F(IvcRecursionConstraintTest, AccumulateTwo)
 {
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::SMALL_TEST;
+    ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
     // construct a mock app_circuit
     Builder app_circuit = construct_mock_app_circuit(ivc);
@@ -185,7 +185,7 @@ TEST_F(IvcRecursionConstraintTest, AccumulateTwo)
 TEST_F(IvcRecursionConstraintTest, AccumulateFour)
 {
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::SMALL_TEST;
+    ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
     // construct a mock app_circuit
     Builder app_circuit_0 = construct_mock_app_circuit(ivc);
@@ -232,7 +232,7 @@ TEST_F(IvcRecursionConstraintTest, AccumulateTwoFailure)
     VerifierInputs alternative_verification_queue_entry;
     {
         ClientIVC ivc;
-        ivc.trace_structure = TraceStructure::SMALL_TEST;
+        ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
         // construct and accumulate a mock app circuit with a single unique public input
         Builder app_circuit = construct_mock_app_circuit(ivc);
@@ -254,7 +254,7 @@ TEST_F(IvcRecursionConstraintTest, AccumulateTwoFailure)
     // valid) witnesses during constraint system construction VS recursive verifier construction.
 
     ClientIVC ivc;
-    ivc.trace_structure = TraceStructure::SMALL_TEST;
+    ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
     // construct and accumulate a mock app circuit with a single unique public input
     Builder app_circuit = construct_mock_app_circuit(ivc);

barretenberg/cpp/src/barretenberg/dsl/acir_proofs/c_bind.cpp

@@ -98,7 +98,7 @@ WASM_EXPORT void acir_fold_and_verify_program_stack(uint8_t const* acir_vec,
 
     ClientIVC ivc;
     ivc.auto_verify_mode = true;
-    ivc.trace_structure = TraceStructure::SMALL_TEST;
+    ivc.trace_settings.structure = TraceStructure::SMALL_TEST;
 
     bool is_kernel = false;
     while (!program_stack.empty()) {

barretenberg/cpp/src/barretenberg/examples/join_split/join_split.test.cpp

@@ -703,7 +703,7 @@ TEST_F(join_split_tests, test_0_input_notes_and_detect_circuit_change)
     // The below part detects any changes in the join-split circuit
     constexpr size_t DYADIC_CIRCUIT_SIZE = 1 << 16;
 
-    constexpr uint256_t CIRCUIT_HASH("0x2b30566e4d921ea9b0c76802d86ea5b8381ffa78ef143af1b0d0e3045862cb6b");
+    constexpr uint256_t CIRCUIT_HASH("0xe833d0ffaa99f39ca31ef79ded0089b0ec614eb4a528c4e1c4af6221a003fa6e");
 
     const uint256_t circuit_hash = circuit.hash_circuit();
     // circuit is finalized now

barretenberg/cpp/src/barretenberg/flavor/flavor.hpp

@@ -360,7 +360,7 @@ template <typename T>
 concept IsUltraPlonkFlavor = IsAnyOf<T, plonk::flavor::Ultra, UltraKeccakFlavor>;
 
 template <typename T>
-concept IsUltraPlonkOrHonk = IsAnyOf<T, plonk::flavor::Ultra, UltraFlavor, UltraKeccakFlavor, UltraFlavorWithZK, MegaFlavor>;
+concept IsUltraPlonkOrHonk = IsAnyOf<T, plonk::flavor::Ultra, UltraFlavor, UltraKeccakFlavor, UltraFlavorWithZK, MegaFlavor, MegaZKFlavor>;
 
 template <typename T>
 concept IsHonkFlavor = IsAnyOf<T, UltraFlavor, UltraKeccakFlavor, UltraFlavorWithZK, MegaFlavor, MegaZKFlavor>;