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//! The cost estimator takes high-level parameters for a circuit design, and estimates the
//! verification cost, as well as resulting proof size.
use std::collections::HashSet;
use std::{iter, num::ParseIntError, str::FromStr};
use crate::plonk::Circuit;
use halo2_middleware::ff::{Field, FromUniformBytes};
use serde::Deserialize;
use serde_derive::Serialize;
use super::MockProver;
/// Supported commitment schemes
#[derive(Debug, Eq, PartialEq)]
pub enum CommitmentScheme {
/// KZG with GWC19 multi-open strategy
KZGGWC,
/// KZG with BDFG20 multi-open strategy
KZGSHPLONK,
}
/// Options to build a circuit specification to measure the cost model of.
#[derive(Debug)]
pub struct CostOptions {
/// An advice column with the given rotations. May be repeated.
pub advice: Vec<Poly>,
/// An instance column with the given rotations. May be repeated.
pub instance: Vec<Poly>,
/// A fixed column with the given rotations. May be repeated.
pub fixed: Vec<Poly>,
/// Maximum degree of the custom gates.
pub gate_degree: usize,
/// Maximum degree of the constraint system.
pub max_degree: usize,
/// A lookup over N columns with max input degree I and max table degree T. May be repeated.
pub lookup: Vec<Lookup>,
/// A permutation over N columns. May be repeated.
pub permutation: Permutation,
/// A shuffle over N columns with max input degree I and max shuffle degree T. May be repeated.
pub shuffle: Vec<Shuffle>,
/// 2^K bound on the number of rows.
pub k: usize,
}
/// Structure holding polynomial related data for benchmarks
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub struct Poly {
/// Rotations for the given polynomial
pub rotations: Vec<isize>,
}
impl FromStr for Poly {
type Err = ParseIntError;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let mut rotations: Vec<isize> =
s.split(',').map(|r| r.parse()).collect::<Result<_, _>>()?;
rotations.sort_unstable();
Ok(Poly { rotations })
}
}
/// Structure holding the Lookup related data for circuit benchmarks.
#[derive(Debug, Clone)]
pub struct Lookup;
impl Lookup {
fn queries(&self) -> impl Iterator<Item = Poly> {
// - product commitments at x and \omega x
// - input commitments at x and x_inv
// - table commitments at x
let product = "0,1".parse().unwrap();
let input = "0,-1".parse().unwrap();
let table = "0".parse().unwrap();
iter::empty()
.chain(Some(product))
.chain(Some(input))
.chain(Some(table))
}
}
/// Number of permutation enabled columns
#[derive(Debug, Clone, Deserialize, Serialize)]
pub struct Permutation {
columns: usize,
}
impl Permutation {
fn queries(&self) -> impl Iterator<Item = Poly> {
// - product commitments at x and x_inv
// - polynomial commitments at x
let product = "0,-1".parse().unwrap();
let poly = "0".parse().unwrap();
iter::empty()
.chain(Some(product))
.chain(iter::repeat(poly).take(self.columns))
}
}
/// Structure holding the [Shuffle] related data for circuit benchmarks.
#[derive(Debug, Clone)]
pub struct Shuffle;
impl Shuffle {
fn queries(&self) -> impl Iterator<Item = Poly> {
// Open shuffle product commitment at x and \omega x
let shuffle = "0, 1".parse().unwrap();
iter::empty().chain(Some(shuffle))
}
}
/// High-level specifications of an abstract circuit.
#[derive(Debug, Deserialize, Serialize)]
pub struct ModelCircuit {
/// Power-of-2 bound on the number of rows in the circuit.
pub k: usize,
/// Maximum degree of the circuit.
pub max_deg: usize,
/// Number of advice columns.
pub advice_columns: usize,
/// Number of lookup arguments.
pub lookups: usize,
/// Equality constraint enabled columns.
pub permutations: usize,
/// Number of shuffle arguments
pub shuffles: usize,
/// Number of distinct column queries across all gates.
pub column_queries: usize,
/// Number of distinct sets of points in the multiopening argument.
pub point_sets: usize,
/// Size of the proof for the circuit
pub size: usize,
}
impl CostOptions {
/// Convert [CostOptions] to [ModelCircuit]. The proof sizè is computed depending on the base
/// and scalar field size of the curve used, together with the [CommitmentScheme].
pub fn into_model_circuit<const COMM: usize, const SCALAR: usize>(
&self,
comm_scheme: CommitmentScheme,
) -> ModelCircuit {
let mut queries: Vec<_> = iter::empty()
.chain(self.advice.iter())
.chain(self.instance.iter())
.chain(self.fixed.iter())
.cloned()
.chain(self.lookup.iter().flat_map(|l| l.queries()))
.chain(self.permutation.queries())
.chain(self.shuffle.iter().flat_map(|s| s.queries()))
.chain(iter::repeat("0".parse().unwrap()).take(self.max_degree - 1))
.collect();
let column_queries = queries.len();
queries.sort_unstable();
queries.dedup();
let point_sets = queries.len();
let comp_bytes = |points: usize, scalars: usize| points * COMM + scalars * SCALAR;
// PLONK:
// - COMM bytes (commitment) per advice column
// - 3 * COMM bytes (commitments) + 5 * SCALAR bytes (evals) per lookup column
// - COMM bytes (commitment) + 2 * SCALAR bytes (evals) per permutation argument
// - COMM bytes (eval) per column per permutation argument
let plonk = comp_bytes(1, 0) * self.advice.len()
+ comp_bytes(3, 5) * self.lookup.len()
+ comp_bytes(1, 2 + self.permutation.columns);
// Vanishing argument:
// - (max_deg - 1) * COMM bytes (commitments) + (max_deg - 1) * SCALAR bytes (h_evals)
// for quotient polynomial
// - SCALAR bytes (eval) per column query
let vanishing =
comp_bytes(self.max_degree - 1, self.max_degree - 1) + comp_bytes(0, column_queries);
// Multiopening argument:
// - f_commitment (COMM bytes)
// - SCALAR bytes (evals) per set of points in multiopen argument
let multiopen = comp_bytes(1, point_sets);
let polycomm = match comm_scheme {
CommitmentScheme::KZGGWC => {
let mut nr_rotations = HashSet::new();
for poly in self.advice.iter() {
nr_rotations.extend(poly.rotations.clone());
}
for poly in self.fixed.iter() {
nr_rotations.extend(poly.rotations.clone());
}
for poly in self.instance.iter() {
nr_rotations.extend(poly.rotations.clone());
}
// Polycommit GWC:
// - number_rotations * COMM bytes
comp_bytes(nr_rotations.len(), 0)
}
CommitmentScheme::KZGSHPLONK => {
// Polycommit SHPLONK:
// - quotient polynomial commitment (COMM bytes)
comp_bytes(1, 0)
}
};
let size = plonk + vanishing + multiopen + polycomm;
ModelCircuit {
k: self.k,
max_deg: self.max_degree,
advice_columns: self.advice.len(),
lookups: self.lookup.len(),
permutations: self.permutation.columns,
shuffles: self.shuffle.len(),
column_queries,
point_sets,
size,
}
}
}
/// Given a Plonk circuit, this function returns a [ModelCircuit]
pub fn from_circuit_to_model_circuit<
F: Ord + Field + FromUniformBytes<64>,
C: Circuit<F>,
const COMM: usize,
const SCALAR: usize,
>(
k: u32,
circuit: &C,
instances: Vec<Vec<F>>,
comm_scheme: CommitmentScheme,
) -> ModelCircuit {
let options = from_circuit_to_cost_model_options(k, circuit, instances);
options.into_model_circuit::<COMM, SCALAR>(comm_scheme)
}
/// Given a Plonk circuit, this function returns [CostOptions]
pub fn from_circuit_to_cost_model_options<F: Ord + Field + FromUniformBytes<64>, C: Circuit<F>>(
k: u32,
circuit: &C,
instances: Vec<Vec<F>>,
) -> CostOptions {
let prover = MockProver::run(k, circuit, instances).unwrap();
let cs = prover.cs;
let fixed = {
// init the fixed polynomials with no rotations
let mut fixed = vec![Poly { rotations: vec![] }; cs.num_fixed_columns()];
for (col, rot) in cs.fixed_queries() {
fixed[col.index()].rotations.push(rot.0 as isize);
}
fixed
};
let advice = {
// init the advice polynomials with no rotations
let mut advice = vec![Poly { rotations: vec![] }; cs.num_advice_columns()];
for (col, rot) in cs.advice_queries() {
advice[col.index()].rotations.push(rot.0 as isize);
}
advice
};
let instance = {
// init the instance polynomials with no rotations
let mut instance = vec![Poly { rotations: vec![] }; cs.num_instance_columns()];
for (col, rot) in cs.instance_queries() {
instance[col.index()].rotations.push(rot.0 as isize);
}
instance
};
let lookup = { cs.lookups().iter().map(|_| Lookup).collect::<Vec<_>>() };
let permutation = Permutation {
columns: cs.permutation().get_columns().len(),
};
let shuffle = { cs.shuffles.iter().map(|_| Shuffle).collect::<Vec<_>>() };
let gate_degree = cs
.gates
.iter()
.flat_map(|gate| gate.polynomials().iter().map(|poly| poly.degree()))
.max()
.unwrap_or(0);
let k = prover.k.try_into().unwrap();
CostOptions {
advice,
instance,
fixed,
gate_degree,
max_degree: cs.degree(),
lookup,
permutation,
shuffle,
k,
}
}