circuit::layouter::RegionLayouter: Introduce add_to_lookup() method

Co-authored-by: Avi Dessauer <avi.dessauer@platonic.systems>

halo2_proofs/src/circuit.rs

@@ -4,6 +4,8 @@ use std::{fmt, marker::PhantomData};
 
 use ff::Field;
 
+#[cfg(feature = "unstable-dynamic-lookups")]
+use crate::plonk::TableTag;
 use crate::plonk::{Advice, Any, Assigned, Column, Error, Fixed, Instance, Selector, TableColumn};
 
 mod value;
@@ -204,6 +206,12 @@ impl<'r, F: Field> Region<'r, F> {
             .enable_selector(&|| annotation().into(), selector, offset)
     }
 
+    /// Enables a dynamic table lookup at the given offset.
+    #[cfg(feature = "unstable-dynamic-lookups")]
+    pub fn add_to_lookup(&mut self, table: TableTag, offset: usize) -> Result<(), Error> {
+        self.region.add_to_lookup(table, offset)
+    }
+
     /// Assign an advice column value (witness).
     ///
     /// Even though `to` has `FnMut` bounds, it is guaranteed to be called at most once.

halo2_proofs/src/circuit/floor_planner/single_pass.rs

@@ -5,6 +5,8 @@ use std::marker::PhantomData;
 
 use ff::Field;
 
+#[cfg(feature = "unstable-dynamic-lookups")]
+use crate::plonk::TableTag;
 use crate::{
     circuit::{
         layouter::{RegionColumn, RegionLayouter, RegionShape},
@@ -259,6 +261,13 @@ impl<'r, 'a, F: Field, CS: Assignment<F> + 'a> RegionLayouter<F>
         )
     }
 
+    #[cfg(feature = "unstable-dynamic-lookups")]
+    fn add_to_lookup(&mut self, table: TableTag, offset: usize) -> Result<(), Error> {
+        self.layouter
+            .cs
+            .add_to_lookup(table, *self.layouter.regions[*self.region_index] + offset)
+    }
+
     fn assign_advice<'v>(
         &'v mut self,
         annotation: &'v (dyn Fn() -> String + 'v),

halo2_proofs/src/circuit/floor_planner/v1.rs

@@ -374,6 +374,13 @@ impl<'r, 'a, F: Field, CS: Assignment<F> + 'a> RegionLayouter<F> for V1Region<'r
         )
     }
 
+    #[cfg(feature = "unstable-dynamic-lookups")]
+    fn add_to_lookup(&mut self, table: crate::plonk::TableTag, offset: usize) -> Result<(), Error> {
+        self.plan
+            .cs
+            .add_to_lookup(table, *self.plan.regions[*self.region_index] + offset)
+    }
+
     fn assign_advice<'v>(
         &'v mut self,
         annotation: &'v (dyn Fn() -> String + 'v),

halo2_proofs/src/circuit/layouter.rs

@@ -51,6 +51,10 @@ pub trait RegionLayouter<F: Field>: fmt::Debug {
         offset: usize,
     ) -> Result<(), Error>;
 
+    /// Enables a dynamic table lookup at the given offset.
+    #[cfg(feature = "unstable-dynamic-lookups")]
+    fn add_to_lookup(&mut self, table: TableTag, offset: usize) -> Result<(), Error>;
+
     /// Assign an advice column value (witness)
     fn assign_advice<'v>(
         &'v mut self,
@@ -215,6 +219,14 @@ impl<F: Field> RegionLayouter<F> for RegionShape {
         Ok(())
     }
 
+    #[cfg(feature = "unstable-dynamic-lookups")]
+    fn add_to_lookup(&mut self, table: TableTag, offset: usize) -> Result<(), Error> {
+        // Track the tag's fixed column as part of the region's shape.
+        self.columns.insert(table.into());
+        self.row_count = cmp::max(self.row_count, offset + 1);
+        Ok(())
+    }
+
     fn assign_advice<'v>(
         &'v mut self,
         _: &'v (dyn Fn() -> String + 'v),

halo2_proofs/src/dev/tfp.rs

@@ -236,6 +236,12 @@ impl<'r, F: Field> RegionLayouter<F> for TracingRegion<'r, F> {
         self.0.enable_selector(annotation, selector, offset)
     }
 
+    #[cfg(feature = "unstable-dynamic-lookups")]
+    fn add_to_lookup(&mut self, table: TableTag, offset: usize) -> Result<(), Error> {
+        debug!(target: "add_to_lookup", table = ?table, offset = ?offset);
+        self.0.add_to_lookup(table, offset)
+    }
+
     fn assign_advice<'v>(
         &'v mut self,
         annotation: &'v (dyn Fn() -> String + 'v),