feat: Keshas skipping plus conditions for grand prod relations (#5766)

Adds Kesha's relation skipping approach for Sumcheck only (i.e. full proof construction / decider), not for folding. My only addition is a condition for skipping the permutation relation. (I added a condition for skipping the lookup relation but it leads to erratic failures in acir tests that I couldn't explain. Details written into an [issue](AztecProtocol/barretenberg#952)). Closes: AztecProtocol/barretenberg#870 (Taking advantage of sorted trace in sumcheck) Master bench: ``` --------------------------------------------------------------------------------------- Benchmark Time CPU Iterations --------------------------------------------------------------------------------------- construct_proof_ultrahonk/sha256 426 ms 397 ms 2 construct_proof_ultrahonk/keccak 1627 ms 1517 ms 1 construct_proof_ultrahonk/ecdsa_verification 2974 ms 2754 ms 1 construct_proof_ultrahonk/merkle_membership 237 ms 219 ms 3 construct_proof_ultrahonk_power_of_2/15 249 ms 231 ms 3 construct_proof_ultrahonk_power_of_2/16 455 ms 427 ms 2 construct_proof_ultrahonk_power_of_2/17 886 ms 831 ms 1 construct_proof_ultrahonk_power_of_2/18 1762 ms 1657 ms 1 construct_proof_ultrahonk_power_of_2/19 3428 ms 3211 ms 1 construct_proof_ultrahonk_power_of_2/20 6752 ms 6344 ms 1 ``` Branch: ``` --------------------------------------------------------------------------------------- Benchmark Time CPU Iterations --------------------------------------------------------------------------------------- construct_proof_ultrahonk/sha256 330 ms 262 ms 3 construct_proof_ultrahonk/keccak 1212 ms 1036 ms 1 construct_proof_ultrahonk/ecdsa_verification 2311 ms 1980 ms 1 construct_proof_ultrahonk/merkle_membership 191 ms 158 ms 4 construct_proof_ultrahonk_power_of_2/15 191 ms 176 ms 4 construct_proof_ultrahonk_power_of_2/16 342 ms 316 ms 2 construct_proof_ultrahonk_power_of_2/17 664 ms 614 ms 1 construct_proof_ultrahonk_power_of_2/18 1271 ms 1174 ms 1 construct_proof_ultrahonk_power_of_2/19 2542 ms 2332 ms 1 construct_proof_ultrahonk_power_of_2/20 4944 ms 4540 ms 1 ```
AztecProtocol · Apr 23, 2024 · d8fcfb5 · d8fcfb5
1 parent ae18396
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diff --git a/barretenberg/cpp/src/barretenberg/plonk_honk_shared/arithmetization/arithmetization.hpp b/barretenberg/cpp/src/barretenberg/plonk_honk_shared/arithmetization/arithmetization.hpp
@@ -259,8 +259,6 @@ template <typename FF_> class UltraHonkArith {
         UltraHonkTraceBlock ecc_op;
         UltraHonkTraceBlock pub_inputs;
         UltraHonkTraceBlock arithmetic;
-        // TODO(https://github.com/AztecProtocol/barretenberg/issues/919): Change: DeltaRangeConstraint -->
-        // DeltaRangeConstraint
         UltraHonkTraceBlock delta_range;
         UltraHonkTraceBlock elliptic;
         UltraHonkTraceBlock aux;

diff --git a/barretenberg/cpp/src/barretenberg/plonk_honk_shared/library/grand_product_library.hpp b/barretenberg/cpp/src/barretenberg/plonk_honk_shared/library/grand_product_library.hpp
@@ -71,6 +71,8 @@ void compute_grand_product(const size_t circuit_size,
         const size_t end = (thread_idx + 1) * block_size;
         typename Flavor::AllValues evaluations;
         auto evaluations_view = evaluations.get_all();
+        // TODO(https://github.com/AztecProtocol/barretenberg/issues/940): construction of evaluations is equivalent to
+        // calling get_row which creates full copies. avoid?
         for (size_t i = start; i < end; ++i) {
             for (auto [eval, full_poly] : zip_view(evaluations_view, full_polynomials_view)) {
                 eval = full_poly.size() > i ? full_poly[i] : 0;

diff --git a/barretenberg/cpp/src/barretenberg/relations/auxiliary_relation.hpp b/barretenberg/cpp/src/barretenberg/relations/auxiliary_relation.hpp
@@ -49,6 +49,15 @@ template <typename FF_> class AuxiliaryRelationImpl {
         1  // RAM consistency sub-relation 3
     };
 
+    /**
+     * @brief Returns true if the contribution from all subrelations for the provided inputs is identically zero
+     *
+     */
+    template <typename AllEntities> inline static bool skip(const AllEntities& in)
+    {
+        return (in.q_aux.value_at(0).is_zero() && in.q_aux.value_at(1).is_zero());
+    }
+
     /**
      * @brief Expression for the generalized permutation sort gate.
      * @details The following explanation is reproduced from the Plonk analog 'plookup_auxiliary_widget':

diff --git a/barretenberg/cpp/src/barretenberg/relations/delta_range_constraint_relation.hpp b/barretenberg/cpp/src/barretenberg/relations/delta_range_constraint_relation.hpp
@@ -14,6 +14,15 @@ template <typename FF_> class DeltaRangeConstraintRelationImpl {
         6  // range constrain sub-relation 4
     };
 
+    /**
+     * @brief Returns true if the contribution from all subrelations for the provided inputs is identically zero
+     *
+     */
+    template <typename AllEntities> inline static bool skip(const AllEntities& in)
+    {
+        return (in.q_delta_range.value_at(0).is_zero() && in.q_delta_range.value_at(1).is_zero());
+    }
+
     /**
      * @brief Expression for the generalized permutation sort gate.
      * @details The relation is defined as C(in(X)...) =

diff --git a/barretenberg/cpp/src/barretenberg/relations/elliptic_relation.hpp b/barretenberg/cpp/src/barretenberg/relations/elliptic_relation.hpp
@@ -14,6 +14,15 @@ template <typename FF_> class EllipticRelationImpl {
         6, // y-coordinate sub-relation
     };
 
+    /**
+     * @brief Returns true if the contribution from all subrelations for the provided inputs is identically zero
+     *
+     */
+    template <typename AllEntities> inline static bool skip(const AllEntities& in)
+    {
+        return (in.q_elliptic.value_at(0).is_zero() && in.q_elliptic.value_at(1).is_zero());
+    }
+
     // TODO(@zac-williamson #2609 find more generic way of doing this)
     static constexpr FF get_curve_b()
     {

diff --git a/barretenberg/cpp/src/barretenberg/relations/lookup_relation.hpp b/barretenberg/cpp/src/barretenberg/relations/lookup_relation.hpp
@@ -31,6 +31,18 @@ template <typename FF_> class LookupRelationImpl {
         4, // grand product construction sub-relation
         0  // left-shiftable polynomial sub-relation
     };
+
+    /**
+     * @brief Returns true if the contribution from all subrelations for the provided inputs is identically zero
+     *
+     */
+    template <typename AllEntities> inline static bool skip([[maybe_unused]] const AllEntities& in)
+    {
+        // TODO(https://github.com/AztecProtocol/barretenberg/issues/952): figure out why skip condition described in
+        // issue causes failures in acir tests.
+        return false;
+    }
+
     /**
      * @brief Get the grand product polynomial object (either from the proving key or AllEntities depending on context)
      *

diff --git a/barretenberg/cpp/src/barretenberg/relations/permutation_relation.hpp b/barretenberg/cpp/src/barretenberg/relations/permutation_relation.hpp
@@ -17,6 +17,18 @@ template <typename FF_> class UltraPermutationRelationImpl {
         0  // left-shiftable polynomial sub-relation
     };
 
+    /**
+     * @brief Returns true if the contribution from all subrelations for the provided inputs is identically zero
+     *
+     */
+    template <typename AllEntities> inline static bool skip(const AllEntities& in)
+    {
+        // If z_perm == z_perm_shift, this implies that none of the wire values for the present input are involved in
+        // non-trivial copy constraints.
+        return (in.z_perm.value_at(0) == in.z_perm_shift.value_at(0) &&
+                in.z_perm.value_at(1) == in.z_perm_shift.value_at(1));
+    }
+
     inline static auto& get_grand_product_polynomial(auto& in) { return in.z_perm; }
     inline static auto& get_shifted_grand_product_polynomial(auto& in) { return in.z_perm_shift; }
 

diff --git a/barretenberg/cpp/src/barretenberg/relations/poseidon2_external_relation.hpp b/barretenberg/cpp/src/barretenberg/relations/poseidon2_external_relation.hpp
@@ -13,6 +13,15 @@ template <typename FF_> class Poseidon2ExternalRelationImpl {
         7, // external poseidon2 round sub-relation for fourth value
     };
 
+    /**
+     * @brief Returns true if the contribution from all subrelations for the provided inputs is identically zero
+     *
+     */
+    template <typename AllEntities> inline static bool skip(const AllEntities& in)
+    {
+        return (in.q_poseidon2_external.value_at(0).is_zero() && in.q_poseidon2_external.value_at(1).is_zero());
+    }
+
     /**
      * @brief Expression for the poseidon2 external round relation, based on E_i in Section 6 of
      * https://eprint.iacr.org/2023/323.pdf.

diff --git a/barretenberg/cpp/src/barretenberg/relations/poseidon2_internal_relation.hpp b/barretenberg/cpp/src/barretenberg/relations/poseidon2_internal_relation.hpp
@@ -15,6 +15,15 @@ template <typename FF_> class Poseidon2InternalRelationImpl {
         7, // internal poseidon2 round sub-relation for fourth value
     };
 
+    /**
+     * @brief Returns true if the contribution from all subrelations for the provided inputs is identically zero
+     *
+     */
+    template <typename AllEntities> inline static bool skip(const AllEntities& in)
+    {
+        return (in.q_poseidon2_internal.value_at(0).is_zero() && in.q_poseidon2_internal.value_at(1).is_zero());
+    }
+
     /**
      * @brief Expression for the poseidon2 internal round relation, based on I_i in Section 6 of
      * https://eprint.iacr.org/2023/323.pdf.

diff --git a/barretenberg/cpp/src/barretenberg/relations/relation_types.hpp b/barretenberg/cpp/src/barretenberg/relations/relation_types.hpp
@@ -111,6 +111,21 @@ consteval std::array<size_t, NUM_SUBRELATIONS> compute_composed_subrelation_part
  *
  */
 
+/**
+ * @brief Check if the relation has a static skip method to determine if accumulation of its result can be
+ * optimised away based on a single check
+ *
+ * @details The skip function should return true if relation can be skipped and false if it can't
+ * @tparam Relation The relation type
+ * @tparam AllEntities The type containing UnivariateViews with witness and selector values
+ */
+template <typename Relation, typename AllEntities>
+concept isSkippable = requires(const AllEntities& input) {
+                          {
+                              Relation::is_active(input)
+                              } -> std::same_as<bool>;
+                      };
+
 /**
  * @brief A wrapper for Relations to expose methods used by the Sumcheck prover or verifier to add the
  * contribution of a given relation to the corresponding accumulator.

diff --git a/barretenberg/cpp/src/barretenberg/relations/ultra_arithmetic_relation.hpp b/barretenberg/cpp/src/barretenberg/relations/ultra_arithmetic_relation.hpp
@@ -12,6 +12,15 @@ template <typename FF_> class UltraArithmeticRelationImpl {
         5  // secondary arithmetic sub-relation
     };
 
+    /**
+     * @brief Returns true if the contribution from all subrelations for the provided inputs is identically zero
+     *
+     */
+    template <typename AllEntities> inline static bool skip(const AllEntities& in)
+    {
+        return (in.q_arith.value_at(0).is_zero() && in.q_arith.value_at(1).is_zero());
+    }
+
     /**
      * @brief Expression for the Ultra Arithmetic gate.
      * @details This relation encapsulates several idenitities, toggled by the value of q_arith in [0, 1, 2, 3, ...].

diff --git a/barretenberg/cpp/src/barretenberg/sumcheck/sumcheck_round.hpp b/barretenberg/cpp/src/barretenberg/sumcheck/sumcheck_round.hpp
@@ -237,8 +237,21 @@ template <typename Flavor> class SumcheckProverRound {
                                          const FF& scaling_factor)
     {
         using Relation = std::tuple_element_t<relation_idx, Relations>;
-        Relation::accumulate(
-            std::get<relation_idx>(univariate_accumulators), extended_edges, relation_parameters, scaling_factor);
+
+        // Check if the relation is skippable to speed up accumulation
+        if constexpr (!isSkippable<Relation, decltype(extended_edges)>) {
+            // If not, accumulate normally
+            Relation::accumulate(
+                std::get<relation_idx>(univariate_accumulators), extended_edges, relation_parameters, scaling_factor);
+        } else {
+            // If so, only compute the contribution if the relation is active
+            if (!Relation::skip(extended_edges, relation_parameters)) {
+                Relation::accumulate(std::get<relation_idx>(univariate_accumulators),
+                                     extended_edges,
+                                     relation_parameters,
+                                     scaling_factor);
+            }
+        }
 
         // Repeat for the next relation.
         if constexpr (relation_idx + 1 < NUM_RELATIONS) {