refactor: Remove VK computation Pg prover flow; improve benchmark to reflect possible optimization

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

@@ -19,6 +19,7 @@ namespace {
 class ClientIVCBench : public benchmark::Fixture {
   public:
     using Builder = GoblinUltraCircuitBuilder;
+    using VerifierFoldData = GoblinMockCircuits::VerifierFoldData;
 
     // Number of function circuits to accumulate(based on Zacs target numbers)
     static constexpr size_t NUM_ITERATIONS_MEDIUM_COMPLEXITY = 6;
@@ -43,28 +44,43 @@ class ClientIVCBench : public benchmark::Fixture {
     {
         const size_t size_hint = 1 << 17; // Size hint for reserving wires/selector vector memory in builders
         // Initialize IVC with function circuit
-        Builder function_circuit{ size_hint, ivc.goblin.op_queue };
+        Builder initial_function_circuit{ size_hint, ivc.goblin.op_queue };
+        GoblinMockCircuits::construct_mock_function_circuit(initial_function_circuit);
+        ivc.initialize(initial_function_circuit);
+        auto kernel_verifier_accumulator = std::make_shared<ClientIVC::VerifierInstance>(ivc.vks.first_func_vk);
+
+        // Accumulate another function circuit
+        Builder function_circuit{ ivc.goblin.op_queue };
         GoblinMockCircuits::construct_mock_function_circuit(function_circuit);
-        ivc.initialize(function_circuit);
+        auto function_fold_proof = ivc.accumulate(function_circuit);
+        VerifierFoldData function_fold_output = { function_fold_proof, ivc.vks.func_vk };
 
-        // Accumulate kernel circuit (first kernel mocked as simple circuit since no folding proofs yet)
+        // Create and accumulate the first folding kernel which only verifies the accumulation of a function circuit
         Builder kernel_circuit{ size_hint, ivc.goblin.op_queue };
-        GoblinMockCircuits::construct_mock_function_circuit(kernel_circuit);
+        kernel_verifier_accumulator = GoblinMockCircuits::construct_mock_folding_kernel(
+            kernel_circuit, function_fold_output, {}, kernel_verifier_accumulator);
         auto kernel_fold_proof = ivc.accumulate(kernel_circuit);
+        VerifierFoldData kernel_fold_output = { kernel_fold_proof, ivc.vks.first_kernel_vk };
 
         auto NUM_CIRCUITS = static_cast<size_t>(state.range(0));
-        NUM_CIRCUITS -= 1; // Subtract one to account for the "initialization" round above
+        // Subtract two to account for the "initialization" round above i.e. we have already folded two function
+        // circuits
+        NUM_CIRCUITS -= 2;
         for (size_t circuit_idx = 0; circuit_idx < NUM_CIRCUITS; ++circuit_idx) {
-
             // Accumulate function circuit
             Builder function_circuit{ size_hint, ivc.goblin.op_queue };
             GoblinMockCircuits::construct_mock_function_circuit(function_circuit);
             auto function_fold_proof = ivc.accumulate(function_circuit);
+            function_fold_output = { function_fold_proof, ivc.vks.func_vk };
 
-            // Accumulate kernel circuit
+            // Create kernel circuit containing the recursive folding verification of a function circuit and a kernel
+            // circuit and accumulate it
             Builder kernel_circuit{ size_hint, ivc.goblin.op_queue };
-            GoblinMockCircuits::construct_mock_folding_kernel(kernel_circuit, function_fold_proof, kernel_fold_proof);
-            auto kernel_fold_proof = ivc.accumulate(kernel_circuit);
+            kernel_verifier_accumulator = GoblinMockCircuits::construct_mock_folding_kernel(
+                kernel_circuit, function_fold_output, kernel_fold_output, kernel_verifier_accumulator);
+
+            kernel_fold_proof = ivc.accumulate(kernel_circuit);
+            kernel_fold_output = { kernel_fold_proof, ivc.vks.kernel_vk };
         }
     }
 };
@@ -76,7 +92,7 @@ class ClientIVCBench : public benchmark::Fixture {
 BENCHMARK_DEFINE_F(ClientIVCBench, Full)(benchmark::State& state)
 {
     ClientIVC ivc;
-
+    ivc.precompute_folding_verification_keys();
     for (auto _ : state) {
         BB_REPORT_OP_COUNT_IN_BENCH(state);
         // Perform a specified number of iterations of function/kernel accumulation
@@ -94,7 +110,7 @@ BENCHMARK_DEFINE_F(ClientIVCBench, Full)(benchmark::State& state)
 BENCHMARK_DEFINE_F(ClientIVCBench, Accumulate)(benchmark::State& state)
 {
     ClientIVC ivc;
-
+    ivc.precompute_folding_verification_keys();
     // Perform a specified number of iterations of function/kernel accumulation
     for (auto _ : state) {
         BB_REPORT_OP_COUNT_IN_BENCH(state);
@@ -109,7 +125,6 @@ BENCHMARK_DEFINE_F(ClientIVCBench, Accumulate)(benchmark::State& state)
 BENCHMARK_DEFINE_F(ClientIVCBench, Decide)(benchmark::State& state)
 {
     ClientIVC ivc;
-
     // Perform a specified number of iterations of function/kernel accumulation
     perform_ivc_accumulation_rounds(state, ivc);
 
@@ -145,7 +160,7 @@ BENCHMARK_DEFINE_F(ClientIVCBench, ECCVM)(benchmark::State& state)
 BENCHMARK_DEFINE_F(ClientIVCBench, Translator)(benchmark::State& state)
 {
     ClientIVC ivc;
-
+    ivc.precompute_folding_verification_keys();
     BB_REPORT_OP_COUNT_IN_BENCH(state);
     // Perform a specified number of iterations of function/kernel accumulation
     perform_ivc_accumulation_rounds(state, ivc);
@@ -159,7 +174,6 @@ BENCHMARK_DEFINE_F(ClientIVCBench, Translator)(benchmark::State& state)
 
 #define ARGS                                                                                                           \
     Arg(ClientIVCBench::NUM_ITERATIONS_MEDIUM_COMPLEXITY)                                                              \
-        ->Arg(1 << 0)                                                                                                  \
         ->Arg(1 << 1)                                                                                                  \
         ->Arg(1 << 2)                                                                                                  \
         ->Arg(1 << 3)                                                                                                  \

barretenberg/cpp/src/barretenberg/benchmark/protogalaxy_bench/protogalaxy.bench.cpp

@@ -30,7 +30,7 @@ template <typename Composer> void fold_one(State& state) noexcept
             static_assert(std::same_as<Flavor, UltraFlavor>);
             bb::mock_proofs::generate_basic_arithmetic_circuit(builder, log2_num_gates);
         }
-        return composer.create_instance(builder);
+        return composer.create_prover_instance(builder);
     };
 
     std::shared_ptr<Instance> instance_1 = construct_instance();

barretenberg/cpp/src/barretenberg/benchmark/protogalaxy_rounds_bench/protogalaxy_rounds.bench.cpp

@@ -13,7 +13,6 @@ void _bench_round(::benchmark::State& state,
                   void (*F)(ProtoGalaxyProver_<ProverInstances_<typename Composer::Flavor, 2>>&))
 {
     using Flavor = typename Composer::Flavor;
-    using Instance = ProverInstance_<Flavor>;
     using Builder = typename Flavor::CircuitBuilder;
 
     bb::srs::init_crs_factory("../srs_db/ignition");
@@ -28,16 +27,16 @@ void _bench_round(::benchmark::State& state,
             static_assert(std::same_as<Flavor, UltraFlavor>);
             bb::mock_proofs::generate_basic_arithmetic_circuit(builder, log2_num_gates);
         }
-        return composer.create_instance(builder);
+        return composer.create_prover_instance(builder);
     };
 
-    std::shared_ptr<Instance> instance_1 = construct_instance();
-    std::shared_ptr<Instance> instance_2 = construct_instance();
+    auto prover_instance_1 = construct_instance();
+    auto prover_instance_2 = construct_instance();
 
-    auto folding_prover = composer.create_folding_prover({ instance_1, instance_2 });
+    auto folding_prover = composer.create_folding_prover({ prover_instance_1, prover_instance_2 });
 
     // prepare the prover state
-    folding_prover.state.accumulator = instance_1;
+    folding_prover.state.accumulator = prover_instance_1;
     folding_prover.state.deltas.resize(log2_num_gates);
     std::fill_n(folding_prover.state.deltas.begin(), log2_num_gates, 0);
     folding_prover.state.perturbator = Flavor::Polynomial::random(1 << log2_num_gates);

barretenberg/cpp/src/barretenberg/benchmark/ultra_bench/mock_proofs.hpp

@@ -54,7 +54,7 @@ inline UltraProver get_prover(UltraComposer& composer,
 {
     UltraComposer::CircuitBuilder builder;
     test_circuit_function(builder, num_iterations);
-    std::shared_ptr<UltraComposer::Instance> instance = composer.create_instance(builder);
+    std::shared_ptr<UltraComposer::ProverInstance> instance = composer.create_prover_instance(builder);
     return composer.create_prover(instance);
 }
 
@@ -64,7 +64,7 @@ inline GoblinUltraProver get_prover(GoblinUltraComposer& composer,
 {
     GoblinUltraComposer::CircuitBuilder builder;
     test_circuit_function(builder, num_iterations);
-    std::shared_ptr<GoblinUltraComposer::Instance> instance = composer.create_instance(builder);
+    std::shared_ptr<GoblinUltraComposer::ProverInstance> instance = composer.create_prover_instance(builder);
     return composer.create_prover(instance);
 }
 

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

@@ -18,7 +18,7 @@ void ClientIVC::initialize(ClientCircuit& circuit)
 {
     goblin.merge(circuit); // Construct new merge proof
     Composer composer;
-    fold_output.accumulator = composer.create_instance(circuit);
+    prover_fold_output.accumulator = composer.create_prover_instance(circuit);
 }
 
 /**
@@ -32,11 +32,10 @@ ClientIVC::FoldProof ClientIVC::accumulate(ClientCircuit& circuit)
 {
     goblin.merge(circuit); // Add recursive merge verifier and construct new merge proof
     Composer composer;
-    auto instance = composer.create_instance(circuit);
-    std::vector<std::shared_ptr<Instance>> instances{ fold_output.accumulator, instance };
-    auto folding_prover = composer.create_folding_prover(instances);
-    fold_output = folding_prover.fold_instances();
-    return fold_output.folding_data;
+    prover_instance = composer.create_prover_instance(circuit);
+    auto folding_prover = composer.create_folding_prover({ prover_fold_output.accumulator, prover_instance });
+    prover_fold_output = folding_prover.fold_instances();
+    return prover_fold_output.folding_data;
 }
 
 /**
@@ -46,7 +45,7 @@ ClientIVC::FoldProof ClientIVC::accumulate(ClientCircuit& circuit)
  */
 ClientIVC::Proof ClientIVC::prove()
 {
-    return { fold_output.folding_data, decider_prove(), goblin.prove() };
+    return { prover_fold_output.folding_data, decider_prove(), goblin.prove() };
 }
 
 /**
@@ -55,19 +54,19 @@ ClientIVC::Proof ClientIVC::prove()
  * @param proof
  * @return bool
  */
-bool ClientIVC::verify(Proof& proof)
+bool ClientIVC::verify(Proof& proof, const std::vector<VerifierAccumulator>& verifier_instances)
 {
     // Goblin verification (merge, eccvm, translator)
     bool goblin_verified = goblin.verify(proof.goblin_proof);
 
     // Decider verification
     Composer composer;
-    auto folding_verifier = composer.create_folding_verifier();
-    bool folding_verified = folding_verifier.verify_folding_proof(proof.fold_proof);
-    // NOTE: Use of member accumulator here will go away with removal of vkey from ProverInstance
-    auto decider_verifier = composer.create_decider_verifier(fold_output.accumulator);
+    auto folding_verifier = composer.create_folding_verifier({ verifier_instances[0], verifier_instances[1] });
+    auto verifier_accumulator = folding_verifier.verify_folding_proof(proof.fold_proof);
+
+    auto decider_verifier = composer.create_decider_verifier(verifier_accumulator);
     bool decision = decider_verifier.verify_proof(proof.decider_proof);
-    return goblin_verified && folding_verified && decision;
+    return goblin_verified && decision;
 }
 
 /**
@@ -78,8 +77,61 @@ bool ClientIVC::verify(Proof& proof)
 HonkProof ClientIVC::decider_prove() const
 {
     Composer composer;
-    auto decider_prover = composer.create_decider_prover(fold_output.accumulator);
+    auto decider_prover = composer.create_decider_prover(prover_fold_output.accumulator);
     return decider_prover.construct_proof();
 }
 
+/**
+ * @brief Precompute the array of verification keys by simulating folding. There will be 4 different verification keys:
+ * initial function verification key (without recursive merge verifier), subsequent function verification key (with
+ * recursive merge verifier), initial kernel verification key (with recursive merge verifier appended, no previous
+ * kernel to fold), "full" kernel verification key( two recursive folding verifiers and merge verifier).
+ *
+ */
+void ClientIVC::precompute_folding_verification_keys()
+{
+    using VerifierInstance = VerifierInstance_<GoblinUltraFlavor>;
+
+    ClientCircuit initial_function_circuit{ goblin.op_queue };
+    GoblinMockCircuits::construct_mock_function_circuit(initial_function_circuit);
+
+    // Initialise both the first prover and verifier accumulator from the inital function circuit
+    initialize(initial_function_circuit);
+    vks.first_func_vk = prover_fold_output.accumulator->verification_key;
+    auto initial_verifier_acc = std::make_shared<VerifierInstance>(vks.first_func_vk);
+
+    // Accumulate the next function circuit
+    ClientCircuit function_circuit{ goblin.op_queue };
+    GoblinMockCircuits::construct_mock_function_circuit(function_circuit);
+    auto function_fold_proof = accumulate(function_circuit);
+
+    // Create its verification key (we have called accumulate so it includes the recursive merge verifier)
+    vks.func_vk = prover_instance->verification_key;
+
+    // Create the initial kernel iteration and precompute its verification key
+    ClientCircuit kernel_circuit{ goblin.op_queue };
+    auto kernel_acc = GoblinMockCircuits::construct_mock_folding_kernel(
+        kernel_circuit, { function_fold_proof, vks.func_vk }, {}, initial_verifier_acc);
+    auto kernel_fold_proof = accumulate(kernel_circuit);
+    vks.first_kernel_vk = prover_instance->verification_key;
+
+    // Create another mock function circuit to run the full kernel
+    function_circuit = ClientCircuit{ goblin.op_queue };
+    GoblinMockCircuits::construct_mock_function_circuit(function_circuit);
+    function_fold_proof = accumulate(function_circuit);
+
+    // Create the full kernel circuit and compute verification key
+    kernel_circuit = GoblinUltraCircuitBuilder{ goblin.op_queue };
+    kernel_acc = GoblinMockCircuits::construct_mock_folding_kernel(
+        kernel_circuit, { function_fold_proof, vks.func_vk }, { kernel_fold_proof, vks.first_kernel_vk }, kernel_acc);
+    kernel_fold_proof = accumulate(kernel_circuit);
+
+    vks.kernel_vk = prover_instance->verification_key;
+
+    // Clean the ivc state
+    goblin.op_queue = std::make_shared<Goblin::OpQueue>();
+    goblin.merge_proof_exists = false;
+    GoblinMockCircuits::perform_op_queue_interactions_for_mock_first_circuit(goblin.op_queue);
+}
+
 } // namespace bb

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

@@ -16,9 +16,13 @@ class ClientIVC {
 
   public:
     using Flavor = GoblinUltraFlavor;
+    using VerificationKey = Flavor::VerificationKey;
     using FF = Flavor::FF;
     using FoldProof = std::vector<FF>;
-    using Accumulator = std::shared_ptr<ProverInstance_<Flavor>>;
+    using ProverAccumulator = std::shared_ptr<ProverInstance_<Flavor>>;
+    using VerifierAccumulator = std::shared_ptr<VerifierInstance_<Flavor>>;
+    using ProverInstance = ProverInstance_<GoblinUltraFlavor>;
+    using VerifierInstance = VerifierInstance_<GoblinUltraFlavor>;
     using ClientCircuit = GoblinUltraCircuitBuilder; // can only be GoblinUltra
 
     // A full proof for the IVC scheme
@@ -28,14 +32,27 @@ class ClientIVC {
         Goblin::Proof goblin_proof;
     };
 
+    struct PrecomputedVerificationKeys {
+        std::shared_ptr<VerificationKey> first_func_vk;
+        std::shared_ptr<VerificationKey> func_vk;
+        std::shared_ptr<VerificationKey> first_kernel_vk;
+        std::shared_ptr<VerificationKey> kernel_vk;
+    };
+
   private:
-    using FoldingOutput = FoldingResult<Flavor>;
-    using Instance = ProverInstance_<GoblinUltraFlavor>;
+    using ProverFoldOutput = FoldingResult<GoblinUltraFlavor>;
     using Composer = GoblinUltraComposer;
+    // Note: We need to save the last instance that was folded in order to compute its verification key, this will not
+    // be needed in the real IVC as they are provided as inputs
 
   public:
     Goblin goblin;
-    FoldingOutput fold_output;
+    ProverFoldOutput prover_fold_output;
+    ProverAccumulator prover_accumulator;
+    PrecomputedVerificationKeys vks;
+    // Note: We need to save the last instance that was folded in order to compute its verification key, this will not
+    // be needed in the real IVC as they are provided as inputs
+    std::shared_ptr<ProverInstance> prover_instance;
 
     ClientIVC();
 
@@ -45,8 +62,12 @@ class ClientIVC {
 
     Proof prove();
 
-    bool verify(Proof& proof);
+    bool verify(Proof& proof, const std::vector<VerifierAccumulator>& verifier_instances);
 
     HonkProof decider_prove() const;
+
+    void decider_prove_and_verify(const VerifierAccumulator&) const;
+
+    void precompute_folding_verification_keys();
 };
 } // namespace bb