perf: reduce sumcheck memory usage

crates/proof-of-sql/src/base/polynomial/multilinear_extension.rs

@@ -1,5 +1,5 @@
 use crate::base::{database::Column, if_rayon, scalar::Scalar, slice_ops};
-use alloc::{rc::Rc, vec::Vec};
+use alloc::vec::Vec;
 use core::{ffi::c_void, fmt::Debug};
 use num_traits::Zero;
 #[cfg(feature = "rayon")]
@@ -15,7 +15,7 @@ pub trait MultilinearExtension<S: Scalar>: Debug {
     fn mul_add(&self, res: &mut [S], multiplier: &S);
 
     /// convert the MLE to a form that can be used in sumcheck
-    fn to_sumcheck_term(&self, num_vars: usize) -> Rc<Vec<S>>;
+    fn to_sumcheck_term(&self, num_vars: usize) -> Vec<S>;
 
     /// pointer to identify the slice forming the MLE
     fn id(&self) -> (*const c_void, usize);
@@ -42,18 +42,17 @@ where
         slice_ops::mul_add_assign(res, *multiplier, &slice_ops::slice_cast(self));
     }
 
-    fn to_sumcheck_term(&self, num_vars: usize) -> Rc<Vec<S>> {
+    fn to_sumcheck_term(&self, num_vars: usize) -> Vec<S> {
         let values = self;
         let n = 1 << num_vars;
         assert!(n >= values.len());
-        let scalars = if_rayon!(values.par_iter(), values.iter())
+        if_rayon!(values.par_iter(), values.iter())
             .map(Into::into)
             .chain(if_rayon!(
                 rayon::iter::repeatn(Zero::zero(), n - values.len()),
                 itertools::repeat_n(Zero::zero(), n - values.len())
             ))
-            .collect();
-        Rc::new(scalars)
+            .collect()
     }
 
     fn id(&self) -> (*const c_void, usize) {
@@ -72,7 +71,7 @@ macro_rules! slice_like_mle_impl {
             (&self[..]).mul_add(res, multiplier)
         }
 
-        fn to_sumcheck_term(&self, num_vars: usize) -> Rc<Vec<S>> {
+        fn to_sumcheck_term(&self, num_vars: usize) -> Vec<S> {
             (&self[..]).to_sumcheck_term(num_vars)
         }
 
@@ -127,7 +126,7 @@ impl<S: Scalar> MultilinearExtension<S> for &Column<'_, S> {
         }
     }
 
-    fn to_sumcheck_term(&self, num_vars: usize) -> Rc<Vec<S>> {
+    fn to_sumcheck_term(&self, num_vars: usize) -> Vec<S> {
         match self {
             Column::Boolean(c) => c.to_sumcheck_term(num_vars),
             Column::Scalar(c) | Column::VarChar((_, c)) | Column::Decimal75(_, _, c) => {
@@ -167,7 +166,7 @@ impl<S: Scalar> MultilinearExtension<S> for Column<'_, S> {
         (&self).mul_add(res, multiplier);
     }
 
-    fn to_sumcheck_term(&self, num_vars: usize) -> Rc<Vec<S>> {
+    fn to_sumcheck_term(&self, num_vars: usize) -> Vec<S> {
         (&self).to_sumcheck_term(num_vars)
     }
 

crates/proof-of-sql/src/sql/proof/composite_polynomial_builder.rs

@@ -32,7 +32,7 @@ impl<S: Scalar> CompositePolynomialBuilder<S> {
             fr_multiplicands_degree1: vec![Zero::zero(); fr.len()],
             fr_multiplicands_rest: vec![],
             zerosum_multiplicands: vec![],
-            fr: fr.to_sumcheck_term(num_sumcheck_variables),
+            fr: fr.to_sumcheck_term(num_sumcheck_variables).into(),
             mles: IndexMap::default(),
         }
     }
@@ -89,8 +89,8 @@ impl<S: Scalar> CompositePolynomialBuilder<S> {
                 deduplicated_terms.push(cached_term.clone());
             } else {
                 let new_term = term.to_sumcheck_term(self.num_sumcheck_variables);
-                self.mles.insert(id, new_term.clone());
-                deduplicated_terms.push(new_term);
+                self.mles.insert(id, new_term.clone().into());
+                deduplicated_terms.push(new_term.into());
             }
         }
         deduplicated_terms
@@ -103,7 +103,9 @@ impl<S: Scalar> CompositePolynomialBuilder<S> {
         res.add_product(
             [
                 self.fr.clone(),
-                (&self.fr_multiplicands_degree1).to_sumcheck_term(self.num_sumcheck_variables),
+                (&self.fr_multiplicands_degree1)
+                    .to_sumcheck_term(self.num_sumcheck_variables)
+                    .into(),
             ],
             One::one(),
         );

crates/proof-of-sql/src/sql/proof/composite_polynomial_builder_test.rs

@@ -33,7 +33,7 @@ fn we_dont_duplicate_repeated_mles() {
     builder.produce_fr_multiplicand(&One::one(), &[Box::new(&mle1), Box::new(&mle2)]);
     let p = builder.make_composite_polynomial();
     assert_eq!(p.products.len(), 3);
-    assert_eq!(p.flattened_ml_extensions.len(), 4);
+    assert_eq!(p.flattened_ml_extensions.len(), 5);
     let pt = [Curve25519Scalar::from(9_268_764_u64)];
     let m0 = Curve25519Scalar::one() - pt[0];
     let m1 = pt[0];