Implement from_qm31_array for QM31. (#679)

crates/prover/src/core/fields/qm31.rs

@@ -3,6 +3,7 @@ use std::ops::{
     Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Rem, RemAssign, Sub, SubAssign,
 };
 
+use super::secure_column::SECURE_EXTENSION_DEGREE;
 use super::{ComplexConjugate, FieldExpOps};
 use crate::core::fields::cm31::CM31;
 use crate::core::fields::m31::M31;
@@ -33,13 +34,23 @@ impl QM31 {
         Self(CM31::from_m31(a, b), CM31::from_m31(c, d))
     }
 
-    pub fn from_m31_array(array: [M31; 4]) -> Self {
+    pub fn from_m31_array(array: [M31; SECURE_EXTENSION_DEGREE]) -> Self {
         Self::from_m31(array[0], array[1], array[2], array[3])
     }
 
-    pub fn to_m31_array(self) -> [M31; 4] {
+    pub fn to_m31_array(self) -> [M31; SECURE_EXTENSION_DEGREE] {
         [self.0 .0, self.0 .1, self.1 .0, self.1 .1]
     }
+
+    /// Returns the combined value, given the values of its composing base field polynomials at that
+    /// point.
+    pub fn from_partial_evals(evals: [Self; SECURE_EXTENSION_DEGREE]) -> Self {
+        let mut res = evals[0];
+        res += evals[1] * Self::from_u32_unchecked(0, 1, 0, 0);
+        res += evals[2] * Self::from_u32_unchecked(0, 0, 1, 0);
+        res += evals[3] * Self::from_u32_unchecked(0, 0, 0, 1);
+        res
+    }
 }
 
 impl Display for QM31 {

crates/prover/src/core/poly/circle/secure_poly.rs

@@ -14,7 +14,7 @@ pub struct SecureCirclePoly<B: FieldOps<BaseField>>(pub [CirclePoly<B>; SECURE_E
 
 impl<B: PolyOps> SecureCirclePoly<B> {
     pub fn eval_at_point(&self, point: CirclePoint<SecureField>) -> SecureField {
-        Self::eval_from_partial_evals(self.eval_columns_at_point(point))
+        SecureField::from_partial_evals(self.eval_columns_at_point(point))
     }
 
     pub fn eval_columns_at_point(
@@ -32,17 +32,6 @@ impl<B: PolyOps> SecureCirclePoly<B> {
     pub fn log_size(&self) -> u32 {
         self[0].log_size()
     }
-
-    /// Evaluates the polynomial at a point, given evaluations of its composing base field
-    /// polynomials at that point.
-    // TODO(AlonH): Move to SecureField and rename.
-    pub fn eval_from_partial_evals(evals: [SecureField; SECURE_EXTENSION_DEGREE]) -> SecureField {
-        let mut res = evals[0];
-        res += evals[1] * SecureField::from_u32_unchecked(0, 1, 0, 0);
-        res += evals[2] * SecureField::from_u32_unchecked(0, 0, 1, 0);
-        res += evals[3] * SecureField::from_u32_unchecked(0, 0, 0, 1);
-        res
-    }
 }
 
 impl<B: FieldOps<BaseField>> Deref for SecureCirclePoly<B> {

crates/prover/src/core/prover/mod.rs

@@ -7,7 +7,7 @@ use super::backend::Backend;
 use super::fields::secure_column::SECURE_EXTENSION_DEGREE;
 use super::fri::FriVerificationError;
 use super::pcs::{CommitmentSchemeProof, TreeVec};
-use super::poly::circle::{CanonicCoset, SecureCirclePoly, MAX_CIRCLE_DOMAIN_LOG_SIZE};
+use super::poly::circle::{CanonicCoset, MAX_CIRCLE_DOMAIN_LOG_SIZE};
 use super::poly::twiddles::TwiddleTree;
 use super::proof_of_work::ProofOfWorkVerificationError;
 use super::{ColumnVec, InteractionElements, LookupValues};
@@ -293,7 +293,7 @@ fn sampled_values_to_mask(
         })
         .collect_vec();
 
-    let composition_oods_value = SecureCirclePoly::<CpuBackend>::eval_from_partial_evals(
+    let composition_oods_value = SecureField::from_partial_evals(
         composition_values
             .iter()
             .flatten()

crates/prover/src/examples/wide_fibonacci/component.rs

@@ -12,7 +12,7 @@ use crate::core::fields::qm31::SecureField;
 use crate::core::fields::secure_column::{SecureColumn, SECURE_EXTENSION_DEGREE};
 use crate::core::fields::FieldExpOps;
 use crate::core::pcs::TreeVec;
-use crate::core::poly::circle::{CanonicCoset, CircleEvaluation, SecureCirclePoly};
+use crate::core::poly::circle::{CanonicCoset, CircleEvaluation};
 use crate::core::poly::BitReversedOrder;
 use crate::core::utils::shifted_secure_combination;
 use crate::core::{ColumnVec, InteractionElements, LookupValues};
@@ -101,10 +101,7 @@ impl WideFibComponent {
         lookup_values: &LookupValues,
     ) {
         let (alpha, z) = (interaction_elements[ALPHA_ID], interaction_elements[Z_ID]);
-        let value =
-            SecureCirclePoly::<CpuBackend>::eval_from_partial_evals(std::array::from_fn(|i| {
-                mask[1][i][0]
-            }));
+        let value = SecureField::from_partial_evals(std::array::from_fn(|i| mask[1][i][0]));
         let numerator = (value
             * shifted_secure_combination(
                 &[
@@ -151,14 +148,8 @@ impl WideFibComponent {
         interaction_elements: &InteractionElements,
     ) {
         let (alpha, z) = (interaction_elements[ALPHA_ID], interaction_elements[Z_ID]);
-        let value =
-            SecureCirclePoly::<CpuBackend>::eval_from_partial_evals(std::array::from_fn(|i| {
-                mask[1][i][0]
-            }));
-        let prev_value =
-            SecureCirclePoly::<CpuBackend>::eval_from_partial_evals(std::array::from_fn(|i| {
-                mask[1][i][1]
-            }));
+        let value = SecureField::from_partial_evals(std::array::from_fn(|i| mask[1][i][0]));
+        let prev_value = SecureField::from_partial_evals(std::array::from_fn(|i| mask[1][i][1]));
         let numerator = (value
             * shifted_secure_combination(
                 &[

crates/prover/src/examples/wide_fibonacci/constraint_eval.rs

@@ -21,7 +21,7 @@ use crate::core::fields::m31::BaseField;
 use crate::core::fields::qm31::SecureField;
 use crate::core::fields::FieldExpOps;
 use crate::core::pcs::TreeVec;
-use crate::core::poly::circle::{CanonicCoset, CircleDomain, CircleEvaluation, SecureCirclePoly};
+use crate::core::poly::circle::{CanonicCoset, CircleDomain, CircleEvaluation};
 use crate::core::poly::BitReversedOrder;
 use crate::core::prover::{BASE_TRACE, INTERACTION_TRACE};
 use crate::core::utils::{
@@ -191,10 +191,9 @@ impl WideFibComponent {
 
         #[allow(clippy::needless_range_loop)]
         for i in 0..trace_eval_domain.size() {
-            let value =
-                SecureCirclePoly::<CpuBackend>::eval_from_partial_evals(std::array::from_fn(|j| {
-                    trace_evals[INTERACTION_TRACE][j][i].into()
-                }));
+            let value = SecureField::from_m31_array(std::array::from_fn(|j| {
+                trace_evals[INTERACTION_TRACE][j][i]
+            }));
             first_point_numerators[i] = accum.random_coeff_powers[self.n_columns() - 1]
                 * ((value
                     * shifted_secure_combination(
@@ -259,19 +258,17 @@ impl WideFibComponent {
 
         #[allow(clippy::needless_range_loop)]
         for i in 0..trace_eval_domain.size() {
-            let value =
-                SecureCirclePoly::<CpuBackend>::eval_from_partial_evals(std::array::from_fn(|j| {
-                    trace_evals[INTERACTION_TRACE][j][i].into()
-                }));
+            let value = SecureField::from_m31_array(std::array::from_fn(|j| {
+                trace_evals[INTERACTION_TRACE][j][i]
+            }));
             let prev_index = previous_bit_reversed_circle_domain_index(
                 i,
                 zero_domain.log_size,
                 trace_eval_domain.log_size(),
             );
-            let prev_value =
-                SecureCirclePoly::<CpuBackend>::eval_from_partial_evals(std::array::from_fn(|j| {
-                    trace_evals[INTERACTION_TRACE][j][prev_index].into()
-                }));
+            let prev_value = SecureField::from_m31_array(std::array::from_fn(|j| {
+                trace_evals[INTERACTION_TRACE][j][prev_index]
+            }));
             numerators[i] = accum.random_coeff_powers[self.n_columns()]
                 * ((value
                     * shifted_secure_combination(