From 71777e78b4e65b4b39124bf2ae424205436cae89 Mon Sep 17 00:00:00 2001
From: hczphn <huancheng@polyhedra.network>
Date: Sun, 22 Feb 2026 02:51:14 +0000
Subject: [PATCH] Reduce memory in SumCheck::prove by accepting ownership
 instead of cloning

Add `prover_init_owned()` that takes `SumOfProductsPoly` by value,
avoiding the expensive clone inside `prover_init()`. Change
`SumCheck::prove()` to accept ownership and use the new init path.

This eliminates one full copy of the polynomial list during proving,
which can be significant for large batched polynomial commitments.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 poly_commit/src/batching.rs             |  2 +-
 sumcheck/src/sumcheck_generic.rs        |  5 +++--
 sumcheck/src/sumcheck_generic/prover.rs | 26 +++++++++++++++++++++++++
 sumcheck/src/sumcheck_generic/tests.rs  |  6 +++---
 4 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/poly_commit/src/batching.rs b/poly_commit/src/batching.rs
index c259aa836..8e39081c2 100644
--- a/poly_commit/src/batching.rs
+++ b/poly_commit/src/batching.rs
@@ -80,7 +80,7 @@ where
     for (tilde_g, tilde_eq) in tilde_gs.iter().zip(tilde_eqs.into_iter()) {
         sumcheck_poly.add_pair(tilde_g.clone(), tilde_eq);
     }
-    let proof = SumCheck::<C::Scalar>::prove(&sumcheck_poly, transcript);
+    let proof = SumCheck::<C::Scalar>::prove(sumcheck_poly, transcript);
     timer.stop();
 
     let a2 = proof.export_point_to_expander();
diff --git a/sumcheck/src/sumcheck_generic.rs b/sumcheck/src/sumcheck_generic.rs
index e2f8e43e9..832725670 100644
--- a/sumcheck/src/sumcheck_generic.rs
+++ b/sumcheck/src/sumcheck_generic.rs
@@ -93,13 +93,14 @@ impl<F: Field> SumCheck<F> {
     /// Generate proof of the sum of polynomial over {0,1}^`num_vars`
     ///
     /// The polynomial is represented in the form of a VirtualPolynomial.
+    /// Takes ownership of poly_list to avoid cloning internally.
     pub fn prove(
-        poly_list: &SumOfProductsPoly<F>,
+        poly_list: SumOfProductsPoly<F>,
         transcript: &mut impl Transcript,
     ) -> IOPProof<F> {
         let num_vars = poly_list.num_vars();
 
-        let mut prover_state = IOPProverState::prover_init(poly_list);
+        let mut prover_state = IOPProverState::prover_init_owned(poly_list);
         let mut challenge = None;
         let mut prover_msgs = Vec::with_capacity(num_vars);
         for _ in 0..num_vars {
diff --git a/sumcheck/src/sumcheck_generic/prover.rs b/sumcheck/src/sumcheck_generic/prover.rs
index e19d62f57..19a547a62 100644
--- a/sumcheck/src/sumcheck_generic/prover.rs
+++ b/sumcheck/src/sumcheck_generic/prover.rs
@@ -31,6 +31,32 @@ impl<F: Field> IOPProverState<F> {
         }
     }
 
+    /// Initialize the prover state by taking ownership of the polynomials,
+    /// avoiding the clone in `prover_init`.
+    pub fn prover_init_owned(polynomials: SumOfProductsPoly<F>) -> Self {
+        let num_vars = polynomials.num_vars();
+        let init_sum_of_vals: Vec<F> = polynomials
+            .f_and_g_pairs
+            .par_iter()
+            .map(|(f, g)| {
+                f.coeffs
+                    .iter()
+                    .zip(g.coeffs.iter())
+                    .map(|(&f, &g)| f * g)
+                    .sum::<F>()
+            })
+            .collect();
+        let eq_prefix = vec![F::one(); polynomials.f_and_g_pairs.len()];
+        Self {
+            challenges: Vec::with_capacity(num_vars),
+            round: 0,
+            init_num_vars: num_vars,
+            mle_list: polynomials,
+            init_sum_of_vals,
+            eq_prefix,
+        }
+    }
+
     /// Receive message from verifier, generate prover message, and proceed to
     /// next round.
     ///
diff --git a/sumcheck/src/sumcheck_generic/tests.rs b/sumcheck/src/sumcheck_generic/tests.rs
index 8a1de31d7..fba3ef8b3 100644
--- a/sumcheck/src/sumcheck_generic/tests.rs
+++ b/sumcheck/src/sumcheck_generic/tests.rs
@@ -89,7 +89,7 @@ fn test_sumcheck_e2e() {
 
             // prover
             let mut transcript = BytesHashTranscript::<Keccak256hasher>::new();
-            let proof = SumCheck::<Fr>::prove(&mle_list, &mut transcript);
+            let proof = SumCheck::<Fr>::prove(mle_list.clone(), &mut transcript);
 
             // verifier
             let mut transcript = BytesHashTranscript::<Keccak256hasher>::new();
@@ -119,7 +119,7 @@ fn test_sumcheck_generic_padding_helper<F: Field, T: Transcript>() {
     };
     let claimed_sum = mle_list.sum();
 
-    let proof = SumCheck::prove(&mle_list, &mut T::new());
+    let proof = SumCheck::prove(mle_list.clone(), &mut T::new());
 
     let padded_mle_list = SumOfProductsPoly {
         f_and_g_pairs: mle_list
@@ -135,7 +135,7 @@ fn test_sumcheck_generic_padding_helper<F: Field, T: Transcript>() {
             .collect(),
     };
 
-    let proof_with_padded_mle_list = SumCheck::prove(&padded_mle_list, &mut T::new());
+    let proof_with_padded_mle_list = SumCheck::prove(padded_mle_list, &mut T::new());
 
     assert_eq!(proof, proof_with_padded_mle_list);