change: Apply memory optimisation technique from Scroll

This incorporates the work done in scroll-tech#28 in order to lower the memory consumption significantly trading off for some performance. A much more deep analysis can be found here: axiom-crypto#17
privacy-scaling-explorations · Mar 2, 2024 · 08fe3e4 · 08fe3e4
1 parent 89e1ebf
commit 08fe3e4
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diff --git a/halo2_backend/src/plonk.rs b/halo2_backend/src/plonk.rs
@@ -6,11 +6,7 @@ use crate::helpers::{
     self, polynomial_slice_byte_length, read_polynomial_vec, write_polynomial_slice,
     SerdeCurveAffine, SerdePrimeField,
 };
-use crate::poly::{
-    Coeff, EvaluationDomain, ExtendedLagrangeCoeff, LagrangeCoeff, PinnedEvaluationDomain,
-    Polynomial,
-};
-use crate::transcript::{ChallengeScalar, EncodedChallenge, Transcript};
+use crate::poly::{Coeff, EvaluationDomain, LagrangeCoeff, PinnedEvaluationDomain, Polynomial};
 use evaluation::Evaluator;
 use halo2_common::plonk::{Circuit, ConstraintSystem, PinnedConstraintSystem};
 use halo2_common::SerdeFormat;
@@ -323,12 +319,11 @@ pub struct PinnedVerificationKey<'a, C: CurveAffine> {
 #[derive(Clone, Debug)]
 pub struct ProvingKey<C: CurveAffine> {
     vk: VerifyingKey<C>,
-    l0: Polynomial<C::Scalar, ExtendedLagrangeCoeff>,
-    l_last: Polynomial<C::Scalar, ExtendedLagrangeCoeff>,
-    l_active_row: Polynomial<C::Scalar, ExtendedLagrangeCoeff>,
+    l0: Polynomial<C::Scalar, Coeff>,
+    l_last: Polynomial<C::Scalar, Coeff>,
+    l_active_row: Polynomial<C::Scalar, Coeff>,
     fixed_values: Vec<Polynomial<C::Scalar, LagrangeCoeff>>,
     fixed_polys: Vec<Polynomial<C::Scalar, Coeff>>,
-    fixed_cosets: Vec<Polynomial<C::Scalar, ExtendedLagrangeCoeff>>,
     permutation: permutation::ProvingKey<C>,
     ev: Evaluator<C>,
 }
@@ -353,7 +348,6 @@ where
             + scalar_len * (self.l0.len() + self.l_last.len() + self.l_active_row.len())
             + polynomial_slice_byte_length(&self.fixed_values)
             + polynomial_slice_byte_length(&self.fixed_polys)
-            + polynomial_slice_byte_length(&self.fixed_cosets)
             + self.permutation.bytes_length()
     }
 }
@@ -379,7 +373,6 @@ where
         self.l_active_row.write(writer, format)?;
         write_polynomial_slice(&self.fixed_values, writer, format)?;
         write_polynomial_slice(&self.fixed_polys, writer, format)?;
-        write_polynomial_slice(&self.fixed_cosets, writer, format)?;
         self.permutation.write(writer, format)?;
         Ok(())
     }
@@ -411,7 +404,6 @@ where
         let l_active_row = Polynomial::read(reader, format)?;
         let fixed_values = read_polynomial_vec(reader, format)?;
         let fixed_polys = read_polynomial_vec(reader, format)?;
-        let fixed_cosets = read_polynomial_vec(reader, format)?;
         let permutation = permutation::ProvingKey::read(reader, format)?;
         let ev = Evaluator::new(vk.cs());
         Ok(Self {
@@ -421,7 +413,6 @@ where
             l_active_row,
             fixed_values,
             fixed_polys,
-            fixed_cosets,
             permutation,
             ev,
         })