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refactor ec points witness assignments #1100

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Oct 31, 2025
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refactor ec points witness assignments #1100

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83 changes: 41 additions & 42 deletions ceno_zkvm/src/instructions/global.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,10 @@ use p3::{
symmetric::Permutation,
};
use rayon::{
iter::{IndexedParallelIterator, IntoParallelIterator, ParallelExtend, ParallelIterator},
iter::{
IndexedParallelIterator, IntoParallelIterator, IntoParallelRefMutIterator, ParallelExtend,
ParallelIterator,
},
prelude::ParallelSliceMut,
slice::ParallelSlice,
};
Expand Down Expand Up @@ -554,50 +557,45 @@ impl<E: ExtensionField> TableCircuit<E> for GlobalChip<E> {
})
.collect::<Result<(), ZKVMError>>()?;

// assign internal nodes in the binary tree for ec point summation
let mut cur_layer_points = steps
.iter()
.map(|step| step.ec_point.point.clone())
.enumerate()
.collect_vec();
// allocate num_rows_padded size, fill points on first half
let mut cur_layer_points_buffer: Vec<_> = (0..num_rows_padded)
.into_par_iter()
.map(|i| {
steps
.get(i)
.map(|step| step.ec_point.point.clone())
.unwrap_or_else(SepticPoint::default)
})
.collect();
// raw_witin offset start from n.
// left node is at b, right node is at b + 1
// op(left node, right node) = offset + b / 2
let mut offset = num_rows_padded / 2;
let mut current_layer_len = cur_layer_points_buffer.len() / 2;

// slope[1,b] = (input[b,0].y - input[b,1].y) / (input[b,0].x - input[b,1].x)
loop {
if cur_layer_points.len() <= 1 {
if current_layer_len <= 1 {
break;
}
// 2b -> b + 2^log_n
let next_layer_offset = cur_layer_points.first().map(|(i, _)| *i / 2 + n).unwrap();
cur_layer_points = cur_layer_points
let (current_layer, next_layer) =
cur_layer_points_buffer.split_at_mut(current_layer_len);
current_layer
.par_chunks(2)
.zip(raw_witin.values[next_layer_offset * num_witin..].par_chunks_mut(num_witin))
.with_min_len(64)
.map(|(pair, instance)| {
// input[1,b] = affine_add(input[b,0], input[b,1])
// the left node is at index 2b, right node is at index 2b+1
// the parent node is at index b + 2^n
let (o, slope, q) = match pair.len() {
2 => {
// l = 2b, r = 2b+1
let (l, p1) = &pair[0];
let (r, p2) = &pair[1];
assert_eq!(*r - *l, 1);

// parent node idx = b + 2^log2_n
let o = n + l / 2;
let slope = (&p1.y - &p2.y) * (&p1.x - &p2.x).inverse().unwrap();
let q = p1.clone() + p2.clone();

(o, slope, q)
}
1 => {
let (l, p) = &pair[0];
let o = n + l / 2;
(o, SepticExtension::zero(), p.clone())
}
_ => unreachable!(),
.zip_eq(next_layer[..current_layer_len / 2].par_iter_mut())
.zip(raw_witin.values[offset * num_witin..].par_chunks_mut(num_witin))
.for_each(|((pair, parent), instance)| {
let p1 = &pair[0];
let p2 = &pair[1];
let (slope, q) = if p2.is_infinity {
// input[1,b] = bypass_left(input[b,0], input[b,1])
(SepticExtension::zero(), p1.clone())
} else {
// input[1,b] = affine_add(input[b,0], input[b,1])
let slope = (&p1.y - &p2.y) * (&p1.x - &p2.x).inverse().unwrap();
let q = p1.clone() + p2.clone();
(slope, q)
};

config
.x
.iter()
Expand All @@ -611,10 +609,11 @@ impl<E: ExtensionField> TableCircuit<E> for GlobalChip<E> {
.for_each(|(witin, fe)| {
set_val!(instance, *witin, *fe);
});

(o, q)
})
.collect::<Vec<_>>();
*parent = q.clone();
});
cur_layer_points_buffer = cur_layer_points_buffer.split_off(current_layer_len);
current_layer_len /= 2;
offset += current_layer_len;
}

let raw_witin = witness::RowMajorMatrix::new_by_inner_matrix(
Expand Down
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