Automatically select FRI reduction arities (#282)

* Automatically select FRI reduction arities

This way when a proof's degree changes, we won't need to manually update the `FriConfig`s of any recursive proofs on top of it.

For now I've added two methods of selecting arities. The first, `ConstantArityBits`, just applies a fixed reduciton arity until the degree has shrunk below a certain threshold. The second, `MinSize`, searches for the sequence of arities that minimizes proof size.

Note that this optimization is approximate -- e.g. it doesn't account for the effect of compression, and doesn't count some minor contributions to proof size, like the Merkle roots from the commit phase. It also assumes we're not using Merkle caps in serialized proofs, and that we're inferring one of the evaluations, even though we haven't made those changes yet.

I think we should generally use `ConstantArityBits` for proofs that we will recurse on, since using a single arity tends to be more recursion-friendly. We could use `MinSize` for generating final bridge proofs, since we won't do further recursion on top of those.

* Fix tests

* Feedback

src/bin/bench_recursion.rs

@@ -4,6 +4,7 @@ use log::info;
 use plonky2::field::crandall_field::CrandallField;
 use plonky2::field::extension_field::Extendable;
 use plonky2::field::field_types::RichField;
+use plonky2::fri::reduction_strategies::FriReductionStrategy;
 use plonky2::fri::FriConfig;
 use plonky2::hash::hashing::SPONGE_WIDTH;
 use plonky2::iop::witness::PartialWitness;
@@ -31,7 +32,7 @@ fn bench_prove<F: RichField + Extendable<D>, const D: usize>() -> Result<()> {
         cap_height: 1,
         fri_config: FriConfig {
             proof_of_work_bits: 15,
-            reduction_arity_bits: vec![2, 2, 2, 2, 2, 2],
+            reduction_strategy: FriReductionStrategy::ConstantArityBits(3, 5),
             num_query_rounds: 35,
         },
     };

src/fri/commitment.rs

@@ -216,7 +216,7 @@ impl<F: RichField> PolynomialBatchCommitment<F> {
             lde_final_poly,
             lde_final_values,
             challenger,
-            &config,
+            &common_data,
             timing,
         );
 

src/fri/mod.rs

@@ -1,24 +1,34 @@
+use crate::fri::reduction_strategies::FriReductionStrategy;
+
 pub mod commitment;
 pub mod proof;
 pub mod prover;
 pub mod recursive_verifier;
+pub mod reduction_strategies;
 pub mod verifier;
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct FriConfig {
     pub proof_of_work_bits: u32,
 
-    /// The arity of each FRI reduction step, expressed (i.e. the log2 of the actual arity).
-    /// For example, `[3, 2, 1]` would describe a FRI reduction tree with 8-to-1 reduction, then
-    /// a 4-to-1 reduction, then a 2-to-1 reduction. After these reductions, the reduced polynomial
-    /// is sent directly.
-    pub reduction_arity_bits: Vec<usize>,
+    pub reduction_strategy: FriReductionStrategy,
 
     /// Number of query rounds to perform.
     pub num_query_rounds: usize,
 }
 
-impl FriConfig {
+/// Parameters which are generated during preprocessing, in contrast to `FriConfig` which is
+/// user-specified.
+#[derive(Debug)]
+pub(crate) struct FriParams {
+    /// The arity of each FRI reduction step, expressed as the log2 of the actual arity.
+    /// For example, `[3, 2, 1]` would describe a FRI reduction tree with 8-to-1 reduction, then
+    /// a 4-to-1 reduction, then a 2-to-1 reduction. After these reductions, the reduced polynomial
+    /// is sent directly.
+    pub reduction_arity_bits: Vec<usize>,
+}
+
+impl FriParams {
     pub(crate) fn total_arities(&self) -> usize {
         self.reduction_arity_bits.iter().sum()
     }

src/fri/proof.rs

@@ -139,7 +139,7 @@ impl<F: RichField + Extendable<D>, const D: usize> FriProof<F, D> {
             ..
         } = self;
         let cap_height = common_data.config.cap_height;
-        let reduction_arity_bits = &common_data.config.fri_config.reduction_arity_bits;
+        let reduction_arity_bits = &common_data.fri_params.reduction_arity_bits;
         let num_reductions = reduction_arity_bits.len();
         let num_initial_trees = query_round_proofs[0].initial_trees_proof.evals_proofs.len();
 
@@ -241,7 +241,7 @@ impl<F: RichField + Extendable<D>, const D: usize> CompressedFriProof<F, D> {
             ..
         } = self;
         let cap_height = common_data.config.cap_height;
-        let reduction_arity_bits = &common_data.config.fri_config.reduction_arity_bits;
+        let reduction_arity_bits = &common_data.fri_params.reduction_arity_bits;
         let num_reductions = reduction_arity_bits.len();
         let num_initial_trees = query_round_proofs
             .initial_trees_proofs

src/fri/prover.rs

@@ -8,7 +8,7 @@ use crate::hash::hash_types::HashOut;
 use crate::hash::hashing::hash_n_to_1;
 use crate::hash::merkle_tree::MerkleTree;
 use crate::iop::challenger::Challenger;
-use crate::plonk::circuit_data::CircuitConfig;
+use crate::plonk::circuit_data::CommonCircuitData;
 use crate::plonk::plonk_common::reduce_with_powers;
 use crate::polynomial::polynomial::{PolynomialCoeffs, PolynomialValues};
 use crate::timed;
@@ -23,7 +23,7 @@ pub fn fri_proof<F: RichField + Extendable<D>, const D: usize>(
     // Evaluation of the polynomial on the large domain.
     lde_polynomial_values: PolynomialValues<F::Extension>,
     challenger: &mut Challenger<F>,
-    config: &CircuitConfig,
+    common_data: &CommonCircuitData<F, D>,
     timing: &mut TimingTree,
 ) -> FriProof<F, D> {
     let n = lde_polynomial_values.values.len();
@@ -37,7 +37,7 @@ pub fn fri_proof<F: RichField + Extendable<D>, const D: usize>(
             lde_polynomial_coeffs,
             lde_polynomial_values,
             challenger,
-            config,
+            common_data,
         )
     );
 
@@ -46,17 +46,12 @@ pub fn fri_proof<F: RichField + Extendable<D>, const D: usize>(
     let pow_witness = timed!(
         timing,
         "find for proof-of-work witness",
-        fri_proof_of_work(current_hash, &config.fri_config)
+        fri_proof_of_work(current_hash, &common_data.config.fri_config)
     );
 
     // Query phase
-    let query_round_proofs = fri_prover_query_rounds(
-        initial_merkle_trees,
-        &trees,
-        challenger,
-        n,
-        &config.fri_config,
-    );
+    let query_round_proofs =
+        fri_prover_query_rounds(initial_merkle_trees, &trees, challenger, n, common_data);
 
     FriProof {
         commit_phase_merkle_caps: trees.iter().map(|t| t.cap.clone()).collect(),
@@ -70,14 +65,15 @@ fn fri_committed_trees<F: RichField + Extendable<D>, const D: usize>(
     mut coeffs: PolynomialCoeffs<F::Extension>,
     mut values: PolynomialValues<F::Extension>,
     challenger: &mut Challenger<F>,
-    config: &CircuitConfig,
+    common_data: &CommonCircuitData<F, D>,
 ) -> (Vec<MerkleTree<F>>, PolynomialCoeffs<F::Extension>) {
+    let config = &common_data.config;
     let mut trees = Vec::new();
 
     let mut shift = F::MULTIPLICATIVE_GROUP_GENERATOR;
-    let num_reductions = config.fri_config.reduction_arity_bits.len();
+    let num_reductions = common_data.fri_params.reduction_arity_bits.len();
     for i in 0..num_reductions {
-        let arity = 1 << config.fri_config.reduction_arity_bits[i];
+        let arity = 1 << common_data.fri_params.reduction_arity_bits[i];
 
         reverse_index_bits_in_place(&mut values.values);
         let chunked_values = values
@@ -136,10 +132,10 @@ fn fri_prover_query_rounds<F: RichField + Extendable<D>, const D: usize>(
     trees: &[MerkleTree<F>],
     challenger: &mut Challenger<F>,
     n: usize,
-    config: &FriConfig,
+    common_data: &CommonCircuitData<F, D>,
 ) -> Vec<FriQueryRound<F, D>> {
-    (0..config.num_query_rounds)
-        .map(|_| fri_prover_query_round(initial_merkle_trees, trees, challenger, n, config))
+    (0..common_data.config.fri_config.num_query_rounds)
+        .map(|_| fri_prover_query_round(initial_merkle_trees, trees, challenger, n, common_data))
         .collect()
 }
 
@@ -148,7 +144,7 @@ fn fri_prover_query_round<F: RichField + Extendable<D>, const D: usize>(
     trees: &[MerkleTree<F>],
     challenger: &mut Challenger<F>,
     n: usize,
-    config: &FriConfig,
+    common_data: &CommonCircuitData<F, D>,
 ) -> FriQueryRound<F, D> {
     let mut query_steps = Vec::new();
     let x = challenger.get_challenge();
@@ -158,7 +154,7 @@ fn fri_prover_query_round<F: RichField + Extendable<D>, const D: usize>(
         .map(|t| (t.get(x_index).to_vec(), t.prove(x_index)))
         .collect::<Vec<_>>();
     for (i, tree) in trees.iter().enumerate() {
-        let arity_bits = config.reduction_arity_bits[i];
+        let arity_bits = common_data.fri_params.reduction_arity_bits[i];
         let evals = unflatten(tree.get(x_index >> arity_bits));
         let merkle_proof = tree.prove(x_index >> arity_bits);
 

src/fri/recursive_verifier.rs

@@ -122,7 +122,7 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
             "Number of query rounds does not match config."
         );
         debug_assert!(
-            !config.fri_config.reduction_arity_bits.is_empty(),
+            !common_data.fri_params.reduction_arity_bits.is_empty(),
             "Number of reductions should be non-zero."
         );
 
@@ -325,7 +325,12 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
             )
         );
 
-        for (i, &arity_bits) in config.fri_config.reduction_arity_bits.iter().enumerate() {
+        for (i, &arity_bits) in common_data
+            .fri_params
+            .reduction_arity_bits
+            .iter()
+            .enumerate()
+        {
             let evals = &round_proof.steps[i].evals;
 
             // Split x_index into the index of the coset x is in, and the index of x within that coset.
@@ -376,7 +381,10 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
         // to the one sent by the prover.
         let eval = with_context!(
             self,
-            "evaluate final polynomial",
+            &format!(
+                "evaluate final polynomial of length {}",
+                proof.final_poly.len()
+            ),
             proof.final_poly.eval_scalar(self, subgroup_x)
         );
         self.connect_extension(eval, old_eval);

src/fri/reduction_strategies.rs

@@ -0,0 +1,136 @@
+use std::time::Instant;
+
+use log::debug;
+
+/// A method for deciding what arity to use at each reduction layer.
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub enum FriReductionStrategy {
+    /// `ConstantArityBits(arity_bits, final_poly_bits)` applies reductions of arity `2^arity_bits`
+    /// until the polynomial degree is `2^final_poly_bits` or less. This tends to work well in the
+    /// recursive setting, as it avoids needing multiple configurations of gates used in FRI
+    /// verification, such as `InterpolationGate`.
+    ConstantArityBits(usize, usize),
+
+    /// Optimize for size.
+    MinSize,
+}
+
+impl FriReductionStrategy {
+    /// The arity of each FRI reduction step, expressed as the log2 of the actual arity.
+    pub(crate) fn reduction_arity_bits(
+        &self,
+        mut degree_bits: usize,
+        rate_bits: usize,
+        num_queries: usize,
+    ) -> Vec<usize> {
+        match self {
+            &FriReductionStrategy::ConstantArityBits(arity_bits, final_poly_bits) => {
+                let mut result = Vec::new();
+                while result.is_empty() || degree_bits > final_poly_bits {
+                    result.push(arity_bits);
+                    assert!(degree_bits >= arity_bits);
+                    degree_bits -= arity_bits;
+                }
+                result.shrink_to_fit();
+                result
+            }
+
+            &FriReductionStrategy::MinSize => {
+                min_size_arity_bits(degree_bits, rate_bits, num_queries)
+            }
+        }
+    }
+}
+
+fn min_size_arity_bits(degree_bits: usize, rate_bits: usize, num_queries: usize) -> Vec<usize> {
+    let start = Instant::now();
+    let (mut arity_bits, fri_proof_size) =
+        min_size_arity_bits_helper(degree_bits, rate_bits, num_queries, vec![]);
+    arity_bits.shrink_to_fit();
+
+    debug!(
+        "min_size_arity_bits took {:.3}s",
+        start.elapsed().as_secs_f32()
+    );
+    debug!(
+        "Smallest arity_bits {:?} results in estimated FRI proof size of {} elements",
+        arity_bits, fri_proof_size
+    );
+
+    arity_bits
+}
+
+/// Return `(arity_bits, fri_proof_size)`.
+fn min_size_arity_bits_helper(
+    degree_bits: usize,
+    rate_bits: usize,
+    num_queries: usize,
+    prefix: Vec<usize>,
+) -> (Vec<usize>, usize) {
+    // 2^4 is the largest arity we see in optimal reduction sequences in practice. For 2^5 to occur
+    // in an optimal sequence, we would need a really massive polynomial.
+    const MAX_ARITY_BITS: usize = 4;
+
+    let sum_of_arities: usize = prefix.iter().sum();
+    let current_layer_bits = degree_bits + rate_bits - sum_of_arities;
+    assert!(current_layer_bits >= rate_bits);
+
+    let mut best_arity_bits = prefix.clone();
+    let mut best_size = relative_proof_size(degree_bits, rate_bits, num_queries, &prefix);
+
+    // The largest next_arity_bits to search. Note that any optimal arity sequence will be
+    // monotonically non-increasing, as a larger arity will shrink more Merkle proofs if it occurs
+    // earlier in the sequence.
+    let max_arity_bits = prefix
+        .last()
+        .copied()
+        .unwrap_or(MAX_ARITY_BITS)
+        .min(current_layer_bits - rate_bits);
+
+    for next_arity_bits in 1..=max_arity_bits {
+        let mut extended_prefix = prefix.clone();
+        extended_prefix.push(next_arity_bits);
+
+        let (arity_bits, size) =
+            min_size_arity_bits_helper(degree_bits, rate_bits, num_queries, extended_prefix);
+        if size < best_size {
+            best_arity_bits = arity_bits;
+            best_size = size;
+        }
+    }
+
+    (best_arity_bits, best_size)
+}
+
+/// Compute the approximate size of a FRI proof with the given reduction arities. Note that this
+/// ignores initial evaluations, which aren't affected by arities, and some other minor
+/// contributions. The result is measured in field elements.
+fn relative_proof_size(
+    degree_bits: usize,
+    rate_bits: usize,
+    num_queries: usize,
+    arity_bits: &[usize],
+) -> usize {
+    const D: usize = 4;
+
+    let mut current_layer_bits = degree_bits + rate_bits;
+
+    let mut total_elems = 0;
+    for arity_bits in arity_bits {
+        let arity = 1 << arity_bits;
+
+        // Add neighboring evaluations, which are extension field elements.
+        total_elems += (arity - 1) * D * num_queries;
+        // Add siblings in the Merkle path.
+        total_elems += current_layer_bits * 4 * num_queries;
+
+        current_layer_bits -= arity_bits;
+    }
+
+    // Add the final polynomial's coefficients.
+    assert!(current_layer_bits >= rate_bits);
+    let final_poly_len = 1 << (current_layer_bits - rate_bits);
+    total_elems += D * final_poly_len;
+
+    total_elems
+}

src/fri/verifier.rs

@@ -81,7 +81,7 @@ pub(crate) fn verify_fri_proof<F: RichField + Extendable<D>, const D: usize>(
         "Number of query rounds does not match config."
     );
     ensure!(
-        !config.fri_config.reduction_arity_bits.is_empty(),
+        !common_data.fri_params.reduction_arity_bits.is_empty(),
         "Number of reductions should be non-zero."
     );
 
@@ -225,7 +225,6 @@ fn fri_verifier_query_round<F: RichField + Extendable<D>, const D: usize>(
     round_proof: &FriQueryRound<F, D>,
     common_data: &CommonCircuitData<F, D>,
 ) -> Result<()> {
-    let config = &common_data.config.fri_config;
     fri_verify_initial_proof(
         x_index,
         &round_proof.initial_trees_proof,
@@ -247,7 +246,12 @@ fn fri_verifier_query_round<F: RichField + Extendable<D>, const D: usize>(
         common_data,
     );
 
-    for (i, &arity_bits) in config.reduction_arity_bits.iter().enumerate() {
+    for (i, &arity_bits) in common_data
+        .fri_params
+        .reduction_arity_bits
+        .iter()
+        .enumerate()
+    {
         let arity = 1 << arity_bits;
         let evals = &round_proof.steps[i].evals;
 

src/plonk/circuit_builder.rs

@@ -11,6 +11,7 @@ use crate::field::extension_field::{Extendable, FieldExtension};
 use crate::field::fft::fft_root_table;
 use crate::field::field_types::RichField;
 use crate::fri::commitment::PolynomialBatchCommitment;
+use crate::fri::FriParams;
 use crate::gates::arithmetic::{ArithmeticExtensionGate, NUM_ARITHMETIC_OPS};
 use crate::gates::constant::ConstantGate;
 use crate::gates::gate::{Gate, GateInstance, GateRef, PrefixedGate};
@@ -320,15 +321,27 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
         })
     }
 
+    fn fri_params(&self, degree_bits_estimate: usize) -> FriParams {
+        let fri_config = &self.config.fri_config;
+        let reduction_arity_bits = fri_config.reduction_strategy.reduction_arity_bits(
+            degree_bits_estimate,
+            self.config.rate_bits,
+            fri_config.num_query_rounds,
+        );
+        FriParams {
+            reduction_arity_bits,
+        }
+    }
+
     /// The number of polynomial values that will be revealed per opening, both for the "regular"
     /// polynomials and for the Z polynomials. Because calculating these values involves a recursive
     /// dependence (the amount of blinding depends on the degree, which depends on the blinding),
     /// this function takes in an estimate of the degree.
     fn num_blinding_gates(&self, degree_estimate: usize) -> (usize, usize) {
+        let degree_bits_estimate = log2_strict(degree_estimate);
         let fri_queries = self.config.fri_config.num_query_rounds;
         let arities: Vec<usize> = self
-            .config
-            .fri_config
+            .fri_params(degree_bits_estimate)
             .reduction_arity_bits
             .iter()
             .map(|x| 1 << x)
@@ -578,9 +591,10 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
         let degree = self.gate_instances.len();
         info!("Degree after blinding & padding: {}", degree);
         let degree_bits = log2_strict(degree);
+        let fri_params = self.fri_params(degree_bits);
         assert!(
-            self.config.fri_config.total_arities() <= degree_bits,
-            "FRI total reduction arity is too large."
+            fri_params.total_arities() <= degree_bits,
+            "FRI total reduction arity is too large.",
         );
 
         let gates = self.gates.iter().cloned().collect();
@@ -673,6 +687,7 @@ impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
 
         let common = CommonCircuitData {
             config: self.config,
+            fri_params,
             degree_bits,
             gates: prefixed_gates,
             quotient_degree_factor,

src/plonk/circuit_data.rs

@@ -7,7 +7,8 @@ use crate::field::extension_field::Extendable;
 use crate::field::fft::FftRootTable;
 use crate::field::field_types::{Field, RichField};
 use crate::fri::commitment::PolynomialBatchCommitment;
-use crate::fri::FriConfig;
+use crate::fri::reduction_strategies::FriReductionStrategy;
+use crate::fri::{FriConfig, FriParams};
 use crate::gates::gate::PrefixedGate;
 use crate::hash::hash_types::{HashOut, MerkleCapTarget};
 use crate::hash::merkle_tree::MerkleCap;
@@ -47,7 +48,7 @@ impl Default for CircuitConfig {
             cap_height: 1,
             fri_config: FriConfig {
                 proof_of_work_bits: 1,
-                reduction_arity_bits: vec![1, 1, 1, 1],
+                reduction_strategy: FriReductionStrategy::ConstantArityBits(3, 5),
                 num_query_rounds: 1,
             },
         }
@@ -71,7 +72,7 @@ impl CircuitConfig {
             cap_height: 1,
             fri_config: FriConfig {
                 proof_of_work_bits: 1,
-                reduction_arity_bits: vec![1],
+                reduction_strategy: FriReductionStrategy::ConstantArityBits(3, 5),
                 num_query_rounds: 1,
             },
         }
@@ -84,7 +85,7 @@ impl CircuitConfig {
             cap_height: 1,
             fri_config: FriConfig {
                 proof_of_work_bits: 1,
-                reduction_arity_bits: vec![1, 1, 1, 1],
+                reduction_strategy: FriReductionStrategy::ConstantArityBits(3, 5),
                 num_query_rounds: 1,
             },
             ..Self::large_config()
@@ -175,6 +176,8 @@ pub(crate) struct VerifierOnlyCircuitData<F: Field> {
 pub struct CommonCircuitData<F: RichField + Extendable<D>, const D: usize> {
     pub(crate) config: CircuitConfig,
 
+    pub(crate) fri_params: FriParams,
+
     pub(crate) degree_bits: usize,
 
     /// The types of gates used in this circuit, along with their prefixes.
@@ -254,7 +257,7 @@ impl<F: RichField + Extendable<D>, const D: usize> CommonCircuitData<F, D> {
     }
 
     pub fn final_poly_len(&self) -> usize {
-        1 << (self.degree_bits - self.config.fri_config.total_arities())
+        1 << (self.degree_bits - self.fri_params.total_arities())
     }
 }
 

src/plonk/recursive_verifier.rs

@@ -127,10 +127,12 @@ mod tests {
     use log::info;
 
     use super::*;
+    use crate::field::field_types::Field;
     use crate::field::goldilocks_field::GoldilocksField;
     use crate::fri::proof::{
         FriInitialTreeProofTarget, FriProofTarget, FriQueryRoundTarget, FriQueryStepTarget,
     };
+    use crate::fri::reduction_strategies::FriReductionStrategy;
     use crate::fri::FriConfig;
     use crate::gadgets::polynomial::PolynomialCoeffsExtTarget;
     use crate::hash::merkle_proofs::MerkleProofTarget;
@@ -372,9 +374,9 @@ mod tests {
             zero_knowledge: false,
             cap_height: 2,
             fri_config: FriConfig {
-                proof_of_work_bits: 1,
-                reduction_arity_bits: vec![2, 2, 2, 2, 2, 2],
-                num_query_rounds: 40,
+                proof_of_work_bits: 15,
+                reduction_strategy: FriReductionStrategy::ConstantArityBits(3, 5),
+                num_query_rounds: 27,
             },
         };
         let (proof_with_pis, vd, cd) = {
@@ -428,17 +430,15 @@ mod tests {
             cap_height: 3,
             fri_config: FriConfig {
                 proof_of_work_bits: 15,
-                reduction_arity_bits: vec![3, 3, 3],
+                reduction_strategy: FriReductionStrategy::ConstantArityBits(3, 5),
                 num_query_rounds: 27,
             },
         };
         let (proof_with_pis, vd, cd) = {
             let (proof_with_pis, vd, cd) = {
                 let mut builder = CircuitBuilder::<F, D>::new(config.clone());
-                let _two = builder.two();
-                let mut _two = builder.hash_n_to_hash(vec![_two], true).elements[0];
-                for _ in 0..10000 {
-                    _two = builder.mul(_two, _two);
+                for i in 0..8_000 {
+                    builder.constant(F::from_canonical_u64(i));
                 }
                 let data = builder.build();
                 (

src/plonk/verifier.rs

@@ -10,7 +10,7 @@ use crate::plonk::vanishing_poly::eval_vanishing_poly;
 use crate::plonk::vars::EvaluationVars;
 
 pub(crate) fn verify<F: RichField + Extendable<D>, const D: usize>(
-    mut proof_with_pis: ProofWithPublicInputs<F, D>,
+    proof_with_pis: ProofWithPublicInputs<F, D>,
     verifier_data: &VerifierOnlyCircuitData<F>,
     common_data: &CommonCircuitData<F, D>,
 ) -> Result<()> {

src/util/serialization.rs

@@ -277,8 +277,8 @@ impl Buffer {
         let mut fqrs = Vec::with_capacity(config.fri_config.num_query_rounds);
         for _ in 0..config.fri_config.num_query_rounds {
             let initial_trees_proof = self.read_fri_initial_proof(common_data)?;
-            let steps = config
-                .fri_config
+            let steps = common_data
+                .fri_params
                 .reduction_arity_bits
                 .iter()
                 .map(|&ar| self.read_fri_query_step(1 << ar))
@@ -307,7 +307,7 @@ impl Buffer {
         common_data: &CommonCircuitData<F, D>,
     ) -> Result<FriProof<F, D>> {
         let config = &common_data.config;
-        let commit_phase_merkle_caps = (0..config.fri_config.reduction_arity_bits.len())
+        let commit_phase_merkle_caps = (0..common_data.fri_params.reduction_arity_bits.len())
             .map(|_| self.read_merkle_cap(config.cap_height))
             .collect::<Result<Vec<_>>>()?;
         let query_round_proofs = self.read_fri_query_rounds(common_data)?;
@@ -417,8 +417,8 @@ impl Buffer {
         }
         let initial_trees_proofs = HashMap::from_iter(pairs);
 
-        let mut steps = Vec::with_capacity(config.fri_config.reduction_arity_bits.len());
-        for &a in &config.fri_config.reduction_arity_bits {
+        let mut steps = Vec::with_capacity(common_data.fri_params.reduction_arity_bits.len());
+        for &a in &common_data.fri_params.reduction_arity_bits {
             indices.iter_mut().for_each(|x| {
                 *x >>= a;
             });
@@ -458,7 +458,7 @@ impl Buffer {
         common_data: &CommonCircuitData<F, D>,
     ) -> Result<CompressedFriProof<F, D>> {
         let config = &common_data.config;
-        let commit_phase_merkle_caps = (0..config.fri_config.reduction_arity_bits.len())
+        let commit_phase_merkle_caps = (0..common_data.fri_params.reduction_arity_bits.len())
             .map(|_| self.read_merkle_cap(config.cap_height))
             .collect::<Result<Vec<_>>>()?;
         let query_round_proofs = self.read_compressed_fri_query_rounds(common_data)?;