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Merge pull request #290 from zcash/v1-layouter 

V1 layouter
This commit is contained in:
str4d 2021-06-12 18:14:54 +01:00 committed by GitHub
parent eae5049ba2 53c43e85b2
commit 236115917d
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6 changed files with 783 additions and 200 deletions
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2
src/circuit.rs
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@ -59,7 +59,7 @@ impl std::ops::Deref for RegionIndex {
}
/// Starting row of a region in a layouter
#[derive(Clone, Copy, Debug)]
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub struct RegionStart(usize);
impl From<usize> for RegionStart {

213
src/circuit/layouter.rs
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@ -1,13 +1,20 @@
//! Implementations of common circuit layouters.
use std::cmp;
use std::collections::{HashMap, HashSet};
use std::collections::HashSet;
use std::fmt;
use std::marker::PhantomData;
use super::{Cell, Layouter, Region, RegionIndex, RegionStart};
use crate::arithmetic::FieldExt;
use crate::plonk::{Advice, Any, Assignment, Column, Error, Fixed, Permutation, Selector};
use super::{Cell, RegionIndex};
use crate::{
arithmetic::FieldExt,
plonk::{Advice, Any, Column, Error, Fixed, Permutation, Selector},
};
mod single_pass;
pub use single_pass::SingleChipLayouter;
mod v1;
pub use v1::{V1Pass, V1};
/// Helper trait for implementing a custom [`Layouter`].
///
@ -37,6 +44,8 @@ use crate::plonk::{Advice, Any, Assignment, Column, Error, Fixed, Permutation, S
/// TODO: It would be great if we could constrain the columns in these types to be
/// "logical" columns that are guaranteed to correspond to the chip (and have come from
/// `Chip::Config`).
///
/// [`Layouter`]: super::Layouter
pub trait RegionLayouter<F: FieldExt>: fmt::Debug {
/// Enables a selector at the given offset.
fn enable_selector<'v>(
@ -75,100 +84,9 @@ pub trait RegionLayouter<F: FieldExt>: fmt::Debug {
) -> Result<(), Error>;
}
/// A [`Layouter`] for a single-chip circuit.
pub struct SingleChipLayouter<'a, F: FieldExt, CS: Assignment<F> + 'a> {
cs: &'a mut CS,
/// Stores the starting row for each region.
regions: Vec<RegionStart>,
/// Stores the first empty row for each column.
columns: HashMap<Column<Any>, usize>,
_marker: PhantomData<F>,
}
impl<'a, F: FieldExt, CS: Assignment<F> + 'a> fmt::Debug for SingleChipLayouter<'a, F, CS> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("SingleChipLayouter")
.field("regions", &self.regions)
.field("columns", &self.columns)
.finish()
}
}
impl<'a, F: FieldExt, CS: Assignment<F>> SingleChipLayouter<'a, F, CS> {
/// Creates a new single-chip layouter.
pub fn new(cs: &'a mut CS) -> Result<Self, Error> {
let ret = SingleChipLayouter {
cs,
regions: vec![],
columns: HashMap::default(),
_marker: PhantomData,
};
Ok(ret)
}
}
impl<'a, F: FieldExt, CS: Assignment<F> + 'a> Layouter<F> for SingleChipLayouter<'a, F, CS> {
type Root = Self;
fn assign_region<A, AR, N, NR>(&mut self, name: N, mut assignment: A) -> Result<AR, Error>
where
A: FnMut(Region<'_, F>) -> Result<AR, Error>,
N: Fn() -> NR,
NR: Into<String>,
{
let region_index = self.regions.len();
// Get shape of the region.
let mut shape = RegionShape::new(region_index.into());
{
let region: &mut dyn RegionLayouter<F> = &mut shape;
assignment(region.into())?;
}
// Lay out this region. We implement the simplest approach here: position the
// region starting at the earliest row for which none of the columns are in use.
let mut region_start = 0;
for column in &shape.columns {
region_start = cmp::max(region_start, self.columns.get(column).cloned().unwrap_or(0));
}
self.regions.push(region_start.into());
// Update column usage information.
for column in shape.columns {
self.columns.insert(column, region_start + shape.row_count);
}
self.cs.enter_region(name);
let mut region = SingleChipLayouterRegion::new(self, region_index.into());
let result = {
let region: &mut dyn RegionLayouter<F> = &mut region;
assignment(region.into())
}?;
self.cs.exit_region();
Ok(result)
}
fn get_root(&mut self) -> &mut Self::Root {
self
}
fn push_namespace<NR, N>(&mut self, name_fn: N)
where
NR: Into<String>,
N: FnOnce() -> NR,
{
self.cs.push_namespace(name_fn)
}
fn pop_namespace(&mut self, gadget_name: Option<String>) {
self.cs.pop_namespace(gadget_name)
}
}
/// The shape of a region. For a region at a certain index, we track
/// the set of columns it uses as well as the number of rows it uses.
#[derive(Debug)]
#[derive(Clone, Debug)]
pub struct RegionShape {
region_index: RegionIndex,
columns: HashSet<Column<Any>>,
@ -259,104 +177,3 @@ impl<F: FieldExt> RegionLayouter<F> for RegionShape {
Ok(())
}
}
struct SingleChipLayouterRegion<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> {
layouter: &'r mut SingleChipLayouter<'a, F, CS>,
region_index: RegionIndex,
}
impl<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> fmt::Debug
for SingleChipLayouterRegion<'r, 'a, F, CS>
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("SingleChipLayouterRegion")
.field("layouter", &self.layouter)
.field("region_index", &self.region_index)
.finish()
}
}
impl<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> SingleChipLayouterRegion<'r, 'a, F, CS> {
fn new(layouter: &'r mut SingleChipLayouter<'a, F, CS>, region_index: RegionIndex) -> Self {
SingleChipLayouterRegion {
layouter,
region_index,
}
}
}
impl<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> RegionLayouter<F>
for SingleChipLayouterRegion<'r, 'a, F, CS>
{
fn enable_selector<'v>(
&'v mut self,
annotation: &'v (dyn Fn() -> String + 'v),
selector: &Selector,
offset: usize,
) -> Result<(), Error> {
self.layouter.cs.enable_selector(
annotation,
selector,
*self.layouter.regions[*self.region_index] + offset,
)
}
fn assign_advice<'v>(
&'v mut self,
annotation: &'v (dyn Fn() -> String + 'v),
column: Column<Advice>,
offset: usize,
to: &'v mut (dyn FnMut() -> Result<F, Error> + 'v),
) -> Result<Cell, Error> {
self.layouter.cs.assign_advice(
annotation,
column,
*self.layouter.regions[*self.region_index] + offset,
to,
)?;
Ok(Cell {
region_index: self.region_index,
row_offset: offset,
column: column.into(),
})
}
fn assign_fixed<'v>(
&'v mut self,
annotation: &'v (dyn Fn() -> String + 'v),
column: Column<Fixed>,
offset: usize,
to: &'v mut (dyn FnMut() -> Result<F, Error> + 'v),
) -> Result<Cell, Error> {
self.layouter.cs.assign_fixed(
annotation,
column,
*self.layouter.regions[*self.region_index] + offset,
to,
)?;
Ok(Cell {
region_index: self.region_index,
row_offset: offset,
column: column.into(),
})
}
fn constrain_equal(
&mut self,
permutation: &Permutation,
left: Cell,
right: Cell,
) -> Result<(), Error> {
self.layouter.cs.copy(
permutation,
left.column,
*self.layouter.regions[*left.region_index] + left.row_offset,
right.column,
*self.layouter.regions[*right.region_index] + right.row_offset,
)?;
Ok(())
}
}

203
src/circuit/layouter/single_pass.rs Normal file
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@ -0,0 +1,203 @@
use std::cmp;
use std::collections::HashMap;
use std::fmt;
use std::marker::PhantomData;
use super::{RegionLayouter, RegionShape};
use crate::{
arithmetic::FieldExt,
circuit::{Cell, Layouter, Region, RegionIndex, RegionStart},
plonk::{Advice, Any, Assignment, Column, Error, Fixed, Permutation, Selector},
};
/// A [`Layouter`] for a single-chip circuit.
pub struct SingleChipLayouter<'a, F: FieldExt, CS: Assignment<F> + 'a> {
cs: &'a mut CS,
/// Stores the starting row for each region.
regions: Vec<RegionStart>,
/// Stores the first empty row for each column.
columns: HashMap<Column<Any>, usize>,
_marker: PhantomData<F>,
}
impl<'a, F: FieldExt, CS: Assignment<F> + 'a> fmt::Debug for SingleChipLayouter<'a, F, CS> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("SingleChipLayouter")
.field("regions", &self.regions)
.field("columns", &self.columns)
.finish()
}
}
impl<'a, F: FieldExt, CS: Assignment<F>> SingleChipLayouter<'a, F, CS> {
/// Creates a new single-chip layouter.
pub fn new(cs: &'a mut CS) -> Result<Self, Error> {
let ret = SingleChipLayouter {
cs,
regions: vec![],
columns: HashMap::default(),
_marker: PhantomData,
};
Ok(ret)
}
}
impl<'a, F: FieldExt, CS: Assignment<F> + 'a> Layouter<F> for SingleChipLayouter<'a, F, CS> {
type Root = Self;
fn assign_region<A, AR, N, NR>(&mut self, name: N, mut assignment: A) -> Result<AR, Error>
where
A: FnMut(Region<'_, F>) -> Result<AR, Error>,
N: Fn() -> NR,
NR: Into<String>,
{
let region_index = self.regions.len();
// Get shape of the region.
let mut shape = RegionShape::new(region_index.into());
{
let region: &mut dyn RegionLayouter<F> = &mut shape;
assignment(region.into())?;
}
// Lay out this region. We implement the simplest approach here: position the
// region starting at the earliest row for which none of the columns are in use.
let mut region_start = 0;
for column in &shape.columns {
region_start = cmp::max(region_start, self.columns.get(column).cloned().unwrap_or(0));
}
self.regions.push(region_start.into());
// Update column usage information.
for column in shape.columns {
self.columns.insert(column, region_start + shape.row_count);
}
self.cs.enter_region(name);
let mut region = SingleChipLayouterRegion::new(self, region_index.into());
let result = {
let region: &mut dyn RegionLayouter<F> = &mut region;
assignment(region.into())
}?;
self.cs.exit_region();
Ok(result)
}
fn get_root(&mut self) -> &mut Self::Root {
self
}
fn push_namespace<NR, N>(&mut self, name_fn: N)
where
NR: Into<String>,
N: FnOnce() -> NR,
{
self.cs.push_namespace(name_fn)
}
fn pop_namespace(&mut self, gadget_name: Option<String>) {
self.cs.pop_namespace(gadget_name)
}
}
struct SingleChipLayouterRegion<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> {
layouter: &'r mut SingleChipLayouter<'a, F, CS>,
region_index: RegionIndex,
}
impl<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> fmt::Debug
for SingleChipLayouterRegion<'r, 'a, F, CS>
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("SingleChipLayouterRegion")
.field("layouter", &self.layouter)
.field("region_index", &self.region_index)
.finish()
}
}
impl<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> SingleChipLayouterRegion<'r, 'a, F, CS> {
fn new(layouter: &'r mut SingleChipLayouter<'a, F, CS>, region_index: RegionIndex) -> Self {
SingleChipLayouterRegion {
layouter,
region_index,
}
}
}
impl<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> RegionLayouter<F>
for SingleChipLayouterRegion<'r, 'a, F, CS>
{
fn enable_selector<'v>(
&'v mut self,
annotation: &'v (dyn Fn() -> String + 'v),
selector: &Selector,
offset: usize,
) -> Result<(), Error> {
self.layouter.cs.enable_selector(
annotation,
selector,
*self.layouter.regions[*self.region_index] + offset,
)
}
fn assign_advice<'v>(
&'v mut self,
annotation: &'v (dyn Fn() -> String + 'v),
column: Column<Advice>,
offset: usize,
to: &'v mut (dyn FnMut() -> Result<F, Error> + 'v),
) -> Result<Cell, Error> {
self.layouter.cs.assign_advice(
annotation,
column,
*self.layouter.regions[*self.region_index] + offset,
to,
)?;
Ok(Cell {
region_index: self.region_index,
row_offset: offset,
column: column.into(),
})
}
fn assign_fixed<'v>(
&'v mut self,
annotation: &'v (dyn Fn() -> String + 'v),
column: Column<Fixed>,
offset: usize,
to: &'v mut (dyn FnMut() -> Result<F, Error> + 'v),
) -> Result<Cell, Error> {
self.layouter.cs.assign_fixed(
annotation,
column,
*self.layouter.regions[*self.region_index] + offset,
to,
)?;
Ok(Cell {
region_index: self.region_index,
row_offset: offset,
column: column.into(),
})
}
fn constrain_equal(
&mut self,
permutation: &Permutation,
left: Cell,
right: Cell,
) -> Result<(), Error> {
self.layouter.cs.copy(
permutation,
left.column,
*self.layouter.regions[*left.region_index] + left.row_offset,
right.column,
*self.layouter.regions[*right.region_index] + right.row_offset,
)?;
Ok(())
}
}

287
src/circuit/layouter/v1.rs Normal file
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@ -0,0 +1,287 @@
use std::fmt;
use std::marker::PhantomData;
use super::{RegionLayouter, RegionShape};
use crate::{
arithmetic::FieldExt,
circuit::{Cell, Layouter, Region, RegionIndex, RegionStart},
plonk::{Advice, Assignment, Column, Error, Fixed, Permutation, Selector},
};
mod strategy;
/// The version 1 [`Layouter`] provided by `halo2`.
///
/// It is a dual-pass layouter, that has visibility into the entire `Circuit::synthesize`
/// step.
pub struct V1<'a, F: FieldExt, CS: Assignment<F> + 'a> {
cs: &'a mut CS,
/// Stores the starting row for each region.
regions: Vec<RegionStart>,
_marker: PhantomData<F>,
}
impl<'a, F: FieldExt, CS: Assignment<F> + 'a> fmt::Debug for V1<'a, F, CS> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("layouter::V1").finish()
}
}
impl<'a, F: FieldExt, CS: Assignment<F>> V1<'a, F, CS> {
/// Creates a new v1 layouter.
pub fn new(cs: &'a mut CS) -> Result<Self, Error> {
let ret = V1 {
cs,
regions: vec![],
_marker: PhantomData,
};
Ok(ret)
}
/// Runs the layouter to synthesize the circuit.
///
/// Even though `synthesis` has `FnMut` bounds, any value-assignment closures
/// contained within it are guaranteed to be called at most once.
pub fn run<S>(&mut self, mut synthesis: S) -> Result<(), Error>
where
S: FnMut(V1Pass<F, CS>) -> Result<(), Error>,
{
// First pass: measure the regions within the circuit.
let mut measure = MeasurementPass::new();
{
let pass = &mut measure;
synthesis(V1Pass::measure(pass))?;
}
self.regions = strategy::slot_in_biggest_advice_first(measure.regions);
// Second pass: assign the regions.
let mut assign = AssignmentPass::new(self);
{
let pass = &mut assign;
synthesis(V1Pass::assign(pass))?;
}
Ok(())
}
}
#[derive(Debug)]
enum Pass<'p, 'a, F: FieldExt, CS: Assignment<F> + 'a> {
Measurement(&'p mut MeasurementPass),
Assignment(&'p mut AssignmentPass<'p, 'a, F, CS>),
}
/// A single pass of the [`V1`] layouter.
#[derive(Debug)]
pub struct V1Pass<'p, 'a, F: FieldExt, CS: Assignment<F> + 'a>(Pass<'p, 'a, F, CS>);
impl<'p, 'a, F: FieldExt, CS: Assignment<F> + 'a> V1Pass<'p, 'a, F, CS> {
fn measure(pass: &'p mut MeasurementPass) -> Self {
V1Pass(Pass::Measurement(pass))
}
fn assign(pass: &'p mut AssignmentPass<'p, 'a, F, CS>) -> Self {
V1Pass(Pass::Assignment(pass))
}
}
impl<'p, 'a, F: FieldExt, CS: Assignment<F> + 'a> Layouter<F> for V1Pass<'p, 'a, F, CS> {
type Root = Self;
fn assign_region<A, AR, N, NR>(&mut self, name: N, assignment: A) -> Result<AR, Error>
where
A: FnMut(Region<'_, F>) -> Result<AR, Error>,
N: Fn() -> NR,
NR: Into<String>,
{
match &mut self.0 {
Pass::Measurement(pass) => pass.assign_region(assignment),
Pass::Assignment(pass) => pass.assign_region(name, assignment),
}
}
fn get_root(&mut self) -> &mut Self::Root {
self
}
fn push_namespace<NR, N>(&mut self, name_fn: N)
where
NR: Into<String>,
N: FnOnce() -> NR,
{
if let Pass::Assignment(pass) = &mut self.0 {
pass.layouter.cs.push_namespace(name_fn);
}
}
fn pop_namespace(&mut self, gadget_name: Option<String>) {
if let Pass::Assignment(pass) = &mut self.0 {
pass.layouter.cs.pop_namespace(gadget_name);
}
}
}
/// Measures the circuit.
#[derive(Debug)]
pub struct MeasurementPass {
regions: Vec<RegionShape>,
}
impl MeasurementPass {
fn new() -> Self {
MeasurementPass { regions: vec![] }
}
fn assign_region<F: FieldExt, A, AR>(&mut self, mut assignment: A) -> Result<AR, Error>
where
A: FnMut(Region<'_, F>) -> Result<AR, Error>,
{
let region_index = self.regions.len();
// Get shape of the region.
let mut shape = RegionShape::new(region_index.into());
let result = {
let region: &mut dyn RegionLayouter<F> = &mut shape;
assignment(region.into())
}?;
self.regions.push(shape);
Ok(result)
}
}
/// Assigns the circuit.
#[derive(Debug)]
pub struct AssignmentPass<'p, 'a, F: FieldExt, CS: Assignment<F> + 'a> {
layouter: &'p mut V1<'a, F, CS>,
/// Counter tracking which region we need to assign next.
region_index: usize,
}
impl<'p, 'a, F: FieldExt, CS: Assignment<F> + 'a> AssignmentPass<'p, 'a, F, CS> {
fn new(layouter: &'p mut V1<'a, F, CS>) -> Self {
AssignmentPass {
layouter,
region_index: 0,
}
}
fn assign_region<A, AR, N, NR>(&mut self, name: N, mut assignment: A) -> Result<AR, Error>
where
A: FnMut(Region<'_, F>) -> Result<AR, Error>,
N: Fn() -> NR,
NR: Into<String>,
{
// Get the next region we are assigning.
let region_index = self.region_index;
self.region_index += 1;
self.layouter.cs.enter_region(name);
let mut region = V1Region::new(self.layouter, region_index.into());
let result = {
let region: &mut dyn RegionLayouter<F> = &mut region;
assignment(region.into())
}?;
self.layouter.cs.exit_region();
Ok(result)
}
}
struct V1Region<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> {
layouter: &'r mut V1<'a, F, CS>,
region_index: RegionIndex,
}
impl<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> fmt::Debug for V1Region<'r, 'a, F, CS> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("V1Region")
.field("layouter", &self.layouter)
.field("region_index", &self.region_index)
.finish()
}
}
impl<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> V1Region<'r, 'a, F, CS> {
fn new(layouter: &'r mut V1<'a, F, CS>, region_index: RegionIndex) -> Self {
V1Region {
layouter,
region_index,
}
}
}
impl<'r, 'a, F: FieldExt, CS: Assignment<F> + 'a> RegionLayouter<F> for V1Region<'r, 'a, F, CS> {
fn enable_selector<'v>(
&'v mut self,
annotation: &'v (dyn Fn() -> String + 'v),
selector: &Selector,
offset: usize,
) -> Result<(), Error> {
self.layouter.cs.enable_selector(
annotation,
selector,
*self.layouter.regions[*self.region_index] + offset,
)
}
fn assign_advice<'v>(
&'v mut self,
annotation: &'v (dyn Fn() -> String + 'v),
column: Column<Advice>,
offset: usize,
to: &'v mut (dyn FnMut() -> Result<F, Error> + 'v),
) -> Result<Cell, Error> {
self.layouter.cs.assign_advice(
annotation,
column,
*self.layouter.regions[*self.region_index] + offset,
to,
)?;
Ok(Cell {
region_index: self.region_index,
row_offset: offset,
column: column.into(),
})
}
fn assign_fixed<'v>(
&'v mut self,
annotation: &'v (dyn Fn() -> String + 'v),
column: Column<Fixed>,
offset: usize,
to: &'v mut (dyn FnMut() -> Result<F, Error> + 'v),
) -> Result<Cell, Error> {
self.layouter.cs.assign_fixed(
annotation,
column,
*self.layouter.regions[*self.region_index] + offset,
to,
)?;
Ok(Cell {
region_index: self.region_index,
row_offset: offset,
column: column.into(),
})
}
fn constrain_equal(
&mut self,
permutation: &Permutation,
left: Cell,
right: Cell,
) -> Result<(), Error> {
self.layouter.cs.copy(
permutation,
left.column,
*self.layouter.regions[*left.region_index] + left.row_offset,
right.column,
*self.layouter.regions[*right.region_index] + right.row_offset,
)?;
Ok(())
}
}

229
src/circuit/layouter/v1/strategy.rs Normal file
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@ -0,0 +1,229 @@
use std::{
cmp,
collections::{BTreeSet, HashMap},
};
use super::RegionShape;
use crate::{
circuit::RegionStart,
plonk::{Any, Column},
};
/// A region allocated within a column.
#[derive(Clone, Default, Debug, PartialEq, Eq)]
struct AllocatedRegion {
// The starting position of the region.
start: usize,
// The length of the region.
length: usize,
}
impl Ord for AllocatedRegion {
fn cmp(&self, other: &Self) -> cmp::Ordering {
self.start.cmp(&other.start)
}
}
impl PartialOrd for AllocatedRegion {
fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
Some(self.cmp(other))
}
}
/// An area of empty space within a column.
struct EmptySpace {
// The starting position of the empty space.
start: usize,
// The number of rows of empty space, or `None` if unbounded.
end: Option<usize>,
}
/// Allocated rows within a column.
///
/// This is a set of [a_start, a_end) pairs representing disjoint allocated intervals.
#[derive(Clone, Default, Debug)]
struct Allocations(BTreeSet<AllocatedRegion>);
impl Allocations {
/// Return all the *unallocated* nonempty intervals intersecting [start, end).
///
/// `end = None` represents an unbounded end.
fn free_intervals(
&self,
start: usize,
end: Option<usize>,
) -> impl Iterator<Item = EmptySpace> + '_ {
self.0
.iter()
.map(Some)
.chain(Some(None))
.scan(start, move |row, region| {
Some(if let Some(region) = region {
if end.map(|end| region.start >= end).unwrap_or(false) {
None
} else {
let ret = if *row < region.start {
Some(EmptySpace {
start: *row,
end: Some(region.start),
})
} else {
None
};
*row = cmp::max(*row, region.start + region.length);
ret
}
} else if end.map(|end| *row < end).unwrap_or(true) {
Some(EmptySpace { start: *row, end })
} else {
None
})
})
.flatten()
}
}
/// - `start` is the current start row of the region (not of this column).
/// - `slack` is the maximum number of rows the start could be moved down, taking into
/// account prior columns.
fn first_fit_region(
column_allocations: &mut HashMap<Column<Any>, Allocations>,
region_columns: &[Column<Any>],
region_length: usize,
start: usize,
slack: Option<usize>,
) -> Option<usize> {
let (c, remaining_columns) = match region_columns.split_first() {
Some(cols) => cols,
None => return Some(start),
};
let end = slack.map(|slack| start + region_length + slack);
// Iterate over the unallocated non-empty intervals in c that intersect [start, end).
for space in column_allocations
.entry(*c)
.or_default()
.clone()
.free_intervals(start, end)
{
// Do we have enough room for this column of the region in this interval?
let s_slack = space
.end
.map(|end| (end as isize - space.start as isize) - region_length as isize);
if let Some((slack, s_slack)) = slack.zip(s_slack) {
assert!(s_slack <= slack as isize);
}
if s_slack.unwrap_or(0) >= 0 {
let row = first_fit_region(
column_allocations,
remaining_columns,
region_length,
space.start,
s_slack.map(|s| s as usize),
);
if let Some(row) = row {
if let Some(end) = end {
assert!(row + region_length <= end);
}
column_allocations
.get_mut(c)
.unwrap()
.0
.insert(AllocatedRegion {
start: row,
length: region_length,
});
return Some(row);
}
}
}
// No placement worked; the caller will need to try other possibilities.
None
}
/// Positions the regions starting at the earliest row for which none of the columns are
/// in use, taking into account gaps between earlier regions.
fn slot_in(region_shapes: Vec<RegionShape>) -> Vec<(RegionStart, RegionShape)> {
// Tracks the empty regions for each column.
let mut column_allocations: HashMap<Column<Any>, Allocations> = Default::default();
region_shapes
.into_iter()
.map(|region| {
// Sort the region's columns to ensure determinism.
// - An unstable sort is fine, because region.columns() returns a set.
// - The sort order relies on Column's Ord implementation!
let mut region_columns: Vec<_> = region.columns().iter().cloned().collect();
region_columns.sort_unstable();
let region_start = first_fit_region(
&mut column_allocations,
&region_columns,
region.row_count(),
0,
None,
)
.expect("We can always fit a region somewhere");
(region_start.into(), region)
})
.collect()
}
/// Sorts the regions by advice area and then lays them out with the [`slot_in`] strategy.
pub fn slot_in_biggest_advice_first(region_shapes: Vec<RegionShape>) -> Vec<RegionStart> {
let mut sorted_regions: Vec<_> = region_shapes.into_iter().collect();
sorted_regions.sort_unstable_by_key(|shape| {
// Count the number of advice columns
let advice_cols = shape
.columns()
.iter()
.filter(|c| matches!(c.column_type(), Any::Advice))
.count();
// Sort by advice area (since this has the most contention).
advice_cols * shape.row_count()
});
sorted_regions.reverse();
// Lay out the sorted regions.
let mut regions = slot_in(sorted_regions);
// Un-sort the regions so they match the original indexing.
regions.sort_unstable_by_key(|(_, region)| region.region_index().0);
regions.into_iter().map(|(start, _)| start).collect()
}
#[test]
fn test_slot_in() {
let regions = vec![
RegionShape {
region_index: 0.into(),
columns: vec![Column::new(0, Any::Advice), Column::new(1, Any::Advice)]
.into_iter()
.collect(),
row_count: 15,
},
RegionShape {
region_index: 1.into(),
columns: vec![Column::new(2, Any::Advice)].into_iter().collect(),
row_count: 10,
},
RegionShape {
region_index: 2.into(),
columns: vec![Column::new(2, Any::Advice), Column::new(0, Any::Advice)]
.into_iter()
.collect(),
row_count: 10,
},
];
assert_eq!(
slot_in(regions)
.into_iter()
.map(|(i, _)| i)
.collect::<Vec<_>>(),
vec![0.into(), 0.into(), 15.into()]
);
}

49
src/plonk/circuit.rs
View File

@ -10,7 +10,10 @@ use super::{lookup, permutation, Error};
use crate::{arithmetic::FieldExt, circuit::Region, poly::Rotation};
/// A column type
pub trait ColumnType: 'static + Sized + std::fmt::Debug {}
pub trait ColumnType:
'static + Sized + Copy + std::fmt::Debug + PartialEq + Eq + Into<Any>
{
}
/// A column with an index and type
#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
@ -34,6 +37,32 @@ impl<C: ColumnType> Column<C> {
}
}
impl<C: ColumnType> Ord for Column<C> {
fn cmp(&self, other: &Self) -> std::cmp::Ordering {
// This ordering is consensus-critical! The layouters rely on deterministic column
// orderings.
match (self.column_type.into(), other.column_type.into()) {
// Indices are assigned within column types.
(Any::Advice, Any::Advice)
| (Any::Instance, Any::Instance)
| (Any::Fixed, Any::Fixed) => self.index.cmp(&other.index),
// Across column types, sort Advice < Instance < Fixed.
(Any::Advice, Any::Instance)
| (Any::Advice, Any::Fixed)
| (Any::Instance, Any::Fixed) => std::cmp::Ordering::Less,
(Any::Fixed, Any::Instance)
| (Any::Fixed, Any::Advice)
| (Any::Instance, Any::Advice) => std::cmp::Ordering::Greater,
}
}
}
impl<C: ColumnType> PartialOrd for Column<C> {
fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
Some(self.cmp(other))
}
}
/// An advice column
#[derive(Clone, Copy, Debug, Eq, PartialEq, Hash)]
pub struct Advice;
@ -62,6 +91,24 @@ impl ColumnType for Fixed {}
impl ColumnType for Instance {}
impl ColumnType for Any {}
impl From<Advice> for Any {
fn from(_: Advice) -> Any {
Any::Advice
}
}
impl From<Fixed> for Any {
fn from(_: Fixed) -> Any {
Any::Fixed
}
}
impl From<Instance> for Any {
fn from(_: Instance) -> Any {
Any::Instance
}
}
impl From<Column<Advice>> for Column<Any> {
fn from(advice: Column<Advice>) -> Column<Any> {
Column {