bench: Add benchmark for degree lowering times

Also, factor out default degree lowering info into function.

Co-authored-by: Alan Szepieniec <alan@neptune.cash>

triton-constraint-builder/Cargo.toml

@@ -29,6 +29,11 @@ twenty-first.workspace = true
 proptest.workspace = true
 proptest-arbitrary-interop.workspace = true
 test-strategy.workspace = true
+divan = "0.1.14"
 
 [lints]
 workspace = true
+
+[[bench]]
+name = "degree_lowering"
+harness = false

triton-constraint-builder/benches/degree_lowering.rs

@@ -0,0 +1,90 @@
+use constraint_circuit::ConstraintCircuitMonad;
+use divan::black_box;
+use triton_constraint_builder::Constraints;
+
+fn main() {
+    divan::main();
+}
+
+#[divan::bench(sample_count = 10)]
+fn assemble_constraints() {
+    black_box(Constraints::all());
+}
+
+#[divan::bench(sample_count = 10)]
+fn initial_constraints(bencher: divan::Bencher) {
+    bencher
+        .with_inputs(|| {
+            let degree_lowering_info = Constraints::default_degree_lowering_info();
+            let constraints = Constraints::initial_constraints();
+            (degree_lowering_info, constraints)
+        })
+        .bench_values(|(degree_lowering_info, mut constraints)| {
+            let (initial_main_substitutions, initial_aux_substitutions) =
+                ConstraintCircuitMonad::lower_to_degree(&mut constraints, degree_lowering_info);
+            black_box((initial_main_substitutions, initial_aux_substitutions));
+        });
+}
+
+#[divan::bench(sample_count = 10)]
+fn consistency_constraints(bencher: divan::Bencher) {
+    bencher
+        .with_inputs(|| {
+            let degree_lowering_info = Constraints::default_degree_lowering_info();
+            let constraints = Constraints::consistency_constraints();
+            (degree_lowering_info, constraints)
+        })
+        .bench_values(|(degree_lowering_info, mut constraints)| {
+            let (consistency_main_substitutions, consistency_aux_substitutions) =
+                ConstraintCircuitMonad::lower_to_degree(&mut constraints, degree_lowering_info);
+            black_box((
+                consistency_main_substitutions,
+                consistency_aux_substitutions,
+            ));
+        });
+}
+
+#[divan::bench(sample_count = 1)]
+fn transition_constraints(bencher: divan::Bencher) {
+    bencher
+        .with_inputs(|| {
+            let degree_lowering_info = Constraints::default_degree_lowering_info();
+            let constraints = Constraints::transition_constraints();
+            (degree_lowering_info, constraints)
+        })
+        .bench_values(|(degree_lowering_info, mut constraints)| {
+            let (transition_main_substitutions, transition_aux_substitutions) =
+                ConstraintCircuitMonad::lower_to_degree(&mut constraints, degree_lowering_info);
+            black_box((transition_main_substitutions, transition_aux_substitutions));
+        });
+}
+
+#[divan::bench(sample_count = 10)]
+fn terminal_constraints(bencher: divan::Bencher) {
+    bencher
+        .with_inputs(|| {
+            let degree_lowering_info = Constraints::default_degree_lowering_info();
+            let constraints = Constraints::terminal_constraints();
+            (degree_lowering_info, constraints)
+        })
+        .bench_values(|(degree_lowering_info, mut constraints)| {
+            let (terminal_main_substitutions, terminal_aux_substitutions) =
+                ConstraintCircuitMonad::lower_to_degree(&mut constraints, degree_lowering_info);
+            black_box((terminal_main_substitutions, terminal_aux_substitutions));
+        });
+}
+
+#[divan::bench(sample_count = 1)]
+fn degree_lower_all(bencher: divan::Bencher) {
+    bencher
+        .with_inputs(|| {
+            let constraints = Constraints::all();
+            let degree_lowering_info = Constraints::default_degree_lowering_info();
+            (degree_lowering_info, constraints)
+        })
+        .bench_values(|(degree_lowering_info, mut constraints)| {
+            let substitutions =
+                constraints.lower_to_target_degree_through_substitutions(degree_lowering_info);
+            black_box(substitutions);
+        });
+}

triton-constraint-builder/src/lib.rs

@@ -42,6 +42,17 @@ impl Constraints {
         }
     }
 
+    // Implementing Default for DegreeLoweringInfo is impossible because the
+    // constants are defined in crate `air` but struct `DegreeLoweringInfo` is
+    // defined in crate `triton-constraint-circuit`. Cfr. orphan rule.
+    pub fn default_degree_lowering_info() -> DegreeLoweringInfo {
+        constraint_circuit::DegreeLoweringInfo {
+            target_degree: air::TARGET_DEGREE,
+            num_main_cols: air::table::NUM_MAIN_COLUMNS,
+            num_aux_cols: air::table::NUM_AUX_COLUMNS,
+        }
+    }
+
     pub fn initial_constraints() -> Vec<ConstraintCircuitMonad<SingleRowIndicator>> {
         let circuit_builder = ConstraintCircuitBuilder::new();
         vec![

triton-vm/build.rs

@@ -10,11 +10,7 @@ fn main() {
     println!("cargo::rerun-if-changed=build.rs");
 
     let mut constraints = Constraints::all();
-    let degree_lowering_info = constraint_circuit::DegreeLoweringInfo {
-        target_degree: air::TARGET_DEGREE,
-        num_main_cols: air::table::NUM_MAIN_COLUMNS,
-        num_aux_cols: air::table::NUM_AUX_COLUMNS,
-    };
+    let degree_lowering_info = Constraints::default_degree_lowering_info();
     let substitutions =
         constraints.lower_to_target_degree_through_substitutions(degree_lowering_info);
     let deg_low_table = substitutions.generate_degree_lowering_table_code();