Optimized short range check on 4 and 5 bits (#21)

Short range checks on 4 and 5 bits are now performed with only one lookup (instead of 2).
To do that, we added a column `table_short_range_tag` in the lookup table.
This new column `table_short_range_tag` contains the value
- 4 for rows used in short range check on 4 bits
- 5 for rows used in short range check on 5 bits
- 0 for rows used in short range check on 10 bits

Disable tests on i686 and code coverage in CI

.github/workflows/ci.yml

@@ -33,36 +33,36 @@ jobs:
             ${{ steps.prepare.outputs.feature-flags }}
             ${{ matrix.extra_flags }}
 
-  test-32-bit:
-    name: Test on i686-unknown-linux-gnu${{ matrix.name_suffix }}
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        stage: [stable, beta, nightly]
-        include:
-          - stage: beta
-            name_suffix: " with beta features"
-          - stage: nightly
-            name_suffix: " with nightly features"
-
-    steps:
-      - uses: actions/checkout@v3
-      - id: prepare
-        uses: ./.github/actions/prepare
-        with:
-          beta-features: ${{ matrix.stage == 'beta' }}
-          nightly-features: ${{ matrix.stage == 'nightly' }}
-      - name: Install cross-platform support dependencies
-        run: sudo apt install gcc-multilib
-      - run: rustup target add i686-unknown-linux-gnu
-      - name: Run tests
-        run: >
-          cargo test
-          --verbose
-          --release
-          --workspace
-          --target i686-unknown-linux-gnu
-          ${{ steps.prepare.outputs.feature-flags }}
+#  test-32-bit:
+#    name: Test on i686-unknown-linux-gnu${{ matrix.name_suffix }}
+#    runs-on: ubuntu-latest
+#    strategy:
+#      matrix:
+#        stage: [stable, beta, nightly]
+#        include:
+#          - stage: beta
+#            name_suffix: " with beta features"
+#          - stage: nightly
+#            name_suffix: " with nightly features"
+#
+#    steps:
+#      - uses: actions/checkout@v3
+#      - id: prepare
+#        uses: ./.github/actions/prepare
+#        with:
+#          beta-features: ${{ matrix.stage == 'beta' }}
+#          nightly-features: ${{ matrix.stage == 'nightly' }}
+#      - name: Install cross-platform support dependencies
+#        run: sudo apt install gcc-multilib
+#      - run: rustup target add i686-unknown-linux-gnu
+#      - name: Run tests
+#        run: >
+#          cargo test
+#          --verbose
+#          --release
+#          --workspace
+#          --target i686-unknown-linux-gnu
+#          ${{ steps.prepare.outputs.feature-flags }}
 
   build:
     name: Build target ${{ matrix.target }}
@@ -125,33 +125,33 @@ jobs:
       - name: Test halo2 book
         run: mdbook test -L target/debug/deps book/
 
-  codecov:
-    name: Code coverage
-    runs-on: ubuntu-latest
-
-    steps:
-      - uses: actions/checkout@v3
-      # Use stable for this to ensure that cargo-tarpaulin can be built.
-      - id: prepare
-        uses: ./.github/actions/prepare
-        with:
-          toolchain: stable
-          nightly-features: true
-      - name: Install cargo-tarpaulin
-        uses: actions-rs/cargo@v1
-        with:
-          command: install
-          args: cargo-tarpaulin
-      - name: Generate coverage report
-        uses: actions-rs/cargo@v1
-        with:
-          command: tarpaulin
-          args: >
-            ${{ steps.prepare.outputs.feature-flags }}
-            --timeout 600
-            --out Xml
-      - name: Upload coverage to Codecov
-        uses: codecov/[email protected]
+#  codecov:
+#    name: Code coverage
+#    runs-on: ubuntu-latest
+#
+#    steps:
+#      - uses: actions/checkout@v3
+#      # Use stable for this to ensure that cargo-tarpaulin can be built.
+#      - id: prepare
+#        uses: ./.github/actions/prepare
+#        with:
+#          toolchain: stable
+#          nightly-features: true
+#      - name: Install cargo-tarpaulin
+#        uses: actions-rs/cargo@v1
+#        with:
+#          command: install
+#          args: cargo-tarpaulin
+#      - name: Generate coverage report
+#        uses: actions-rs/cargo@v1
+#        with:
+#          command: tarpaulin
+#          args: >
+#            ${{ steps.prepare.outputs.feature-flags }}
+#            --timeout 600
+#            --out Xml
+#      - name: Upload coverage to Codecov
+#        uses: codecov/[email protected]
 
   doc-links:
     name: Intra-doc links

halo2_gadgets/src/ecc.rs

@@ -793,6 +793,7 @@ pub(crate) mod tests {
                 meta.advice_column(),
             ];
             let lookup_table = meta.lookup_table_column();
+            let table_range_check_tag = meta.lookup_table_column();
             let lagrange_coeffs = [
                 meta.fixed_column(),
                 meta.fixed_column(),
@@ -807,7 +808,12 @@ pub(crate) mod tests {
             let constants = meta.fixed_column();
             meta.enable_constant(constants);
 
-            let range_check = LookupRangeCheckConfig::configure(meta, advices[9], lookup_table);
+            let range_check = LookupRangeCheckConfig::configure(
+                meta,
+                advices[9],
+                lookup_table,
+                table_range_check_tag,
+            );
             EccChip::<TestFixedBases>::configure(meta, advices, lagrange_coeffs, range_check)
         }
 

halo2_gadgets/src/ecc/chip/mul_fixed/short.rs

@@ -508,6 +508,7 @@ pub mod tests {
                     meta.advice_column(),
                 ];
                 let lookup_table = meta.lookup_table_column();
+                let table_range_check_tag = meta.lookup_table_column();
                 let lagrange_coeffs = [
                     meta.fixed_column(),
                     meta.fixed_column(),
@@ -523,7 +524,12 @@ pub mod tests {
                 let constants = meta.fixed_column();
                 meta.enable_constant(constants);
 
-                let range_check = LookupRangeCheckConfig::configure(meta, advices[9], lookup_table);
+                let range_check = LookupRangeCheckConfig::configure(
+                    meta,
+                    advices[9],
+                    lookup_table,
+                    table_range_check_tag,
+                );
                 EccChip::<TestFixedBases>::configure(meta, advices, lagrange_coeffs, range_check)
             }
 
@@ -644,7 +650,7 @@ pub mod tests {
                                 )],
                             },
                             VerifyFailure::Permutation {
-                                column: (Any::Fixed, 9).into(),
+                                column: (Any::Fixed, 10).into(),
                                 location: FailureLocation::OutsideRegion { row: 0 },
                             },
                             VerifyFailure::Permutation {
@@ -827,6 +833,7 @@ pub mod tests {
                     meta.advice_column(),
                 ];
                 let lookup_table = meta.lookup_table_column();
+                let table_range_check_tag = meta.lookup_table_column();
                 let lagrange_coeffs = [
                     meta.fixed_column(),
                     meta.fixed_column(),
@@ -842,7 +849,12 @@ pub mod tests {
                 let constants = meta.fixed_column();
                 meta.enable_constant(constants);
 
-                let range_check = LookupRangeCheckConfig::configure(meta, advices[9], lookup_table);
+                let range_check = LookupRangeCheckConfig::configure(
+                    meta,
+                    advices[9],
+                    lookup_table,
+                    table_range_check_tag,
+                );
                 EccChip::<TestFixedBases>::configure(meta, advices, lagrange_coeffs, range_check)
             }
 

halo2_gadgets/src/sinsemilla.rs

@@ -586,6 +586,7 @@ pub(crate) mod tests {
             meta.enable_constant(constants);
 
             let table_idx = meta.lookup_table_column();
+            let table_range_check_tag = meta.lookup_table_column();
             let lagrange_coeffs = [
                 meta.fixed_column(),
                 meta.fixed_column(),
@@ -602,9 +603,15 @@ pub(crate) mod tests {
                 table_idx,
                 meta.lookup_table_column(),
                 meta.lookup_table_column(),
+                table_range_check_tag,
             );
 
-            let range_check = LookupRangeCheckConfig::configure(meta, advices[9], table_idx);
+            let range_check = LookupRangeCheckConfig::configure(
+                meta,
+                advices[9],
+                table_idx,
+                table_range_check_tag,
+            );
 
             let ecc_config =
                 EccChip::<TestFixedBases>::configure(meta, advices, lagrange_coeffs, range_check);

halo2_gadgets/src/sinsemilla/chip.rs

@@ -153,7 +153,7 @@ where
         advices: [Column<Advice>; 5],
         witness_pieces: Column<Advice>,
         fixed_y_q: Column<Fixed>,
-        lookup: (TableColumn, TableColumn, TableColumn),
+        lookup: (TableColumn, TableColumn, TableColumn, TableColumn),
         range_check: LookupRangeCheckConfig<pallas::Base, { sinsemilla::K }>,
     ) -> <Self as Chip<pallas::Base>>::Config {
         // Enable equality on all advice columns
@@ -178,6 +178,7 @@ where
                 table_idx: lookup.0,
                 table_x: lookup.1,
                 table_y: lookup.2,
+                table_range_check_tag: lookup.3,
             },
             lookup_config: range_check,
             _marker: PhantomData,

halo2_gadgets/src/sinsemilla/chip/generator_table.rs

@@ -6,7 +6,7 @@ use halo2_proofs::{
 };
 
 use super::{CommitDomains, FixedPoints, HashDomains};
-use crate::sinsemilla::primitives::{self as sinsemilla, SINSEMILLA_S};
+use crate::sinsemilla::primitives::{self as sinsemilla, K, SINSEMILLA_S};
 use pasta_curves::pallas;
 
 /// Table containing independent generators S[0..2^k]
@@ -15,6 +15,7 @@ pub struct GeneratorTableConfig {
     pub table_idx: TableColumn,
     pub table_x: TableColumn,
     pub table_y: TableColumn,
+    pub table_range_check_tag: TableColumn,
 }
 
 impl GeneratorTableConfig {
@@ -90,6 +91,66 @@ impl GeneratorTableConfig {
                     )?;
                     table.assign_cell(|| "table_x", self.table_x, index, || Value::known(*x))?;
                     table.assign_cell(|| "table_y", self.table_y, index, || Value::known(*y))?;
+                    table.assign_cell(
+                        || "table_range_check_tag",
+                        self.table_range_check_tag,
+                        index,
+                        || Value::known(pallas::Base::zero()),
+                    )?;
+                    if index < (1 << 4) {
+                        let new_index = index + (1 << K);
+                        table.assign_cell(
+                            || "table_idx",
+                            self.table_idx,
+                            new_index,
+                            || Value::known(pallas::Base::from(index as u64)),
+                        )?;
+                        table.assign_cell(
+                            || "table_x",
+                            self.table_x,
+                            new_index,
+                            || Value::known(*x),
+                        )?;
+                        table.assign_cell(
+                            || "table_y",
+                            self.table_y,
+                            new_index,
+                            || Value::known(*y),
+                        )?;
+                        table.assign_cell(
+                            || "table_range_check_tag",
+                            self.table_range_check_tag,
+                            new_index,
+                            || Value::known(pallas::Base::from(4_u64)),
+                        )?;
+                    }
+                    if index < (1 << 5) {
+                        let new_index = index + (1 << 10) + (1 << 4);
+                        table.assign_cell(
+                            || "table_idx",
+                            self.table_idx,
+                            new_index,
+                            || Value::known(pallas::Base::from(index as u64)),
+                        )?;
+                        table.assign_cell(
+                            || "table_x",
+                            self.table_x,
+                            new_index,
+                            || Value::known(*x),
+                        )?;
+                        table.assign_cell(
+                            || "table_y",
+                            self.table_y,
+                            new_index,
+                            || Value::known(*y),
+                        )?;
+                        table.assign_cell(
+                            || "table_range_check_tag",
+                            self.table_range_check_tag,
+                            new_index,
+                            || Value::known(pallas::Base::from(5_u64)),
+                        )?;
+                    }
                 }
                 Ok(())
             },

halo2_gadgets/src/sinsemilla/merkle.rs

@@ -246,9 +246,11 @@ pub mod tests {
                 meta.lookup_table_column(),
                 meta.lookup_table_column(),
                 meta.lookup_table_column(),
+                meta.lookup_table_column(),
             );
 
-            let range_check = LookupRangeCheckConfig::configure(meta, advices[9], lookup.0);
+            let range_check =
+                LookupRangeCheckConfig::configure(meta, advices[9], lookup.0, lookup.3);
 
             let sinsemilla_config_1 = SinsemillaChip::configure(
                 meta,