stwo-gpu-constraint-framework 2.0.0

Constraint framework for building AIR constraints with STWO-GPU
Documentation 
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use std::ops::Mul;

use num_traits::Zero;
use stwo::core::fields::m31::BaseField;
use stwo::core::fields::qm31::{SecureField, SECURE_EXTENSION_DEGREE};
use stwo::core::pcs::TreeVec;
use stwo::core::utils::offset_bit_reversed_circle_domain_index;
use stwo::core::Fraction;
use stwo::prover::backend::simd::column::VeryPackedBaseColumn;
use stwo::prover::backend::simd::m31::LOG_N_LANES;
use stwo::prover::backend::simd::very_packed_m31::{
    VeryPackedBaseField, VeryPackedSecureField, LOG_N_VERY_PACKED_ELEMS,
};
use stwo::prover::backend::simd::SimdBackend;
use stwo::prover::backend::Column;
use stwo::prover::poly::circle::CircleEvaluation;
use stwo::prover::poly::BitReversedOrder;

use crate::logup::LogupAtRow;
use crate::{EvalAtRow, INTERACTION_TRACE_IDX};

/// Evaluates constraints at an evaluation domain points.
pub struct SimdDomainEvaluator<'a> {
    pub trace_eval:
        &'a TreeVec<Vec<&'a CircleEvaluation<SimdBackend, BaseField, BitReversedOrder>>>,
    pub column_index_per_interaction: Vec<usize>,
    /// The row index of the simd-vector row to evaluate the constraints at.
    pub vec_row: usize,
    pub random_coeff_powers: &'a [SecureField],
    pub row_res: VeryPackedSecureField,
    pub constraint_index: usize,
    pub domain_log_size: u32,
    pub eval_domain_log_size: u32,
    pub logup: LogupAtRow<Self>,
}
impl<'a> SimdDomainEvaluator<'a> {
    pub fn new(
        trace_eval: &'a TreeVec<Vec<&CircleEvaluation<SimdBackend, BaseField, BitReversedOrder>>>,
        vec_row: usize,
        random_coeff_powers: &'a [SecureField],
        domain_log_size: u32,
        eval_log_size: u32,
        log_size: u32,
        claimed_sum: SecureField,
    ) -> Self {
        Self {
            trace_eval,
            column_index_per_interaction: vec![0; trace_eval.len()],
            vec_row,
            random_coeff_powers,
            row_res: VeryPackedSecureField::zero(),
            constraint_index: 0,
            domain_log_size,
            eval_domain_log_size: eval_log_size,
            logup: LogupAtRow::new(INTERACTION_TRACE_IDX, claimed_sum, log_size),
        }
    }
}
impl EvalAtRow for SimdDomainEvaluator<'_> {
    type F = VeryPackedBaseField;
    type EF = VeryPackedSecureField;

    // TODO(Ohad): Add debug boundary checks.
    fn next_interaction_mask<const N: usize>(
        &mut self,
        interaction: usize,
        offsets: [isize; N],
    ) -> [Self::F; N] {
        let col_index = self.column_index_per_interaction[interaction];
        self.column_index_per_interaction[interaction] += 1;
        offsets.map(|off| {
            // If the offset is 0, we can just return the value directly from this row.
            if off == 0 {
                unsafe {
                    let col = &self
                        .trace_eval
                        .get_unchecked(interaction)
                        .get_unchecked(col_index)
                        .values;
                    let very_packed_col = VeryPackedBaseColumn::transform_under_ref(col);
                    return *very_packed_col.data.get_unchecked(self.vec_row);
                };
            }
            // Otherwise, we need to look up the value at the offset.
            // Since the domain is bit-reversed circle domain ordered, we need to look up the value
            // at the bit-reversed natural order index at an offset.
            VeryPackedBaseField::from_array(std::array::from_fn(|i| {
                let row_index = offset_bit_reversed_circle_domain_index(
                    (self.vec_row << (LOG_N_LANES + LOG_N_VERY_PACKED_ELEMS)) + i,
                    self.domain_log_size,
                    self.eval_domain_log_size,
                    off,
                );
                self.trace_eval[interaction][col_index].at(row_index)
            }))
        })
    }
    fn add_constraint<G>(&mut self, constraint: G)
    where
        Self::EF: Mul<G, Output = Self::EF> + From<G>,
    {
        self.row_res +=
            VeryPackedSecureField::broadcast(self.random_coeff_powers[self.constraint_index])
                * constraint;
        self.constraint_index += 1;
    }

    fn combine_ef(values: [Self::F; SECURE_EXTENSION_DEGREE]) -> Self::EF {
        VeryPackedSecureField::from_very_packed_m31s(values)
    }

    crate::logup_proxy!();
}