From 61a853b94be2bf1b5cf57173e05699eee8ce4ebb Mon Sep 17 00:00:00 2001
From: Robin Salen <salenrobin@gmail.com>
Date: Sun, 30 Jul 2023 19:59:59 -0400
Subject: [PATCH] use reduce_with_powers_u32

---
 plonky2/src/gadgets/split_base.rs | 5 ++++-
 plonky2/src/gates/base_sum.rs     | 8 +++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/plonky2/src/gadgets/split_base.rs b/plonky2/src/gadgets/split_base.rs
index 3dca1f8f01..8bfef33907 100644
--- a/plonky2/src/gadgets/split_base.rs
+++ b/plonky2/src/gadgets/split_base.rs
@@ -103,7 +103,10 @@ impl<F: RichField + Extendable<D>, const B: usize, const D: usize> SimpleGenerat
             .iter()
             .map(|&t| witness.get_bool_target(t))
             .rev()
-            .fold(F::ZERO, |acc, limb| acc.mul_u32(B as u32 + limb as u32));
+            .fold(F::ZERO, |acc, limb| {
+                let t = acc.to_noncanonical_u64() as u128 * B as u128 + limb as u128;
+                F::from_noncanonical_u96((t as u64, (t >> 64) as u32))
+            });
 
         out_buffer.set_target(Target::wire(self.row, BaseSumGate::<B>::WIRE_SUM), sum);
     }
diff --git a/plonky2/src/gates/base_sum.rs b/plonky2/src/gates/base_sum.rs
index 181252a2d3..40fddbe46f 100644
--- a/plonky2/src/gates/base_sum.rs
+++ b/plonky2/src/gates/base_sum.rs
@@ -16,7 +16,9 @@ use crate::iop::target::Target;
 use crate::iop::witness::{PartitionWitness, Witness, WitnessWrite};
 use crate::plonk::circuit_builder::CircuitBuilder;
 use crate::plonk::circuit_data::{CircuitConfig, CommonCircuitData};
-use crate::plonk::plonk_common::{reduce_with_powers, reduce_with_powers_ext_circuit};
+use crate::plonk::plonk_common::{
+    reduce_with_powers, reduce_with_powers_ext_circuit, reduce_with_powers_u32,
+};
 use crate::plonk::vars::{
     EvaluationTargets, EvaluationVars, EvaluationVarsBase, EvaluationVarsBaseBatch,
     EvaluationVarsBasePacked,
@@ -67,7 +69,7 @@ impl<F: RichField + Extendable<D>, const D: usize, const B: usize> Gate<F, D> fo
     fn eval_unfiltered(&self, vars: EvaluationVars<F, D>) -> Vec<F::Extension> {
         let sum = vars.local_wires[Self::WIRE_SUM];
         let limbs = vars.local_wires[self.limbs()].to_vec();
-        let computed_sum = reduce_with_powers(&limbs, F::Extension::from_canonical_usize(B));
+        let computed_sum = reduce_with_powers_u32(&limbs, B as u32);
         let mut constraints = vec![computed_sum - sum];
         for limb in limbs {
             constraints.push(
@@ -156,7 +158,7 @@ impl<F: RichField + Extendable<D>, const D: usize, const B: usize> PackedEvaluab
     ) {
         let sum = vars.local_wires[Self::WIRE_SUM];
         let limbs = vars.local_wires.view(self.limbs());
-        let computed_sum = reduce_with_powers(limbs, F::from_canonical_usize(B));
+        let computed_sum = reduce_with_powers_u32(limbs, B as u32);
 
         yield_constr.one(computed_sum - sum);