Consolidate duplicate distance searches and parallelize the search engine

crates/benchmarks/benches/benchmarks.rs

@@ -17,6 +17,7 @@ use criterion::{Criterion, criterion_group, criterion_main};
 
 mod modules {
     pub mod allocation_overhead;
+    pub mod code_distance;
     pub mod cpu_stabilizer_comparison;
     pub mod dem_builder;
     pub mod dem_sampler;
@@ -58,14 +59,15 @@ use modules::sparse_stab_vs_cpp;
 #[cfg(feature = "stab-tn")]
 use modules::stab_mps_vs_stab_vec;
 use modules::{
-    allocation_overhead, cpu_stabilizer_comparison, dem_builder, dem_sampler, dod_statevec,
-    fault_catalog, measurement_sampling, native_statevec_comparison, noise_models,
+    allocation_overhead, code_distance, cpu_stabilizer_comparison, dem_builder, dem_sampler,
+    dod_statevec, fault_catalog, measurement_sampling, native_statevec_comparison, noise_models,
     pecos_neo_comparison, quizx_eval, rng, set_ops, sparse_stab_w_vs_y, sparse_state_vec, stab_vec,
     stabilizer_sims, state_vec_sims, surface_code, tick_circuit_layout, trig,
 };
 
 fn all_benchmarks(c: &mut Criterion) {
     allocation_overhead::benchmarks(c);
+    code_distance::benchmarks(c);
     stab_vec::benchmarks(c);
     cpu_stabilizer_comparison::benchmarks(c);
     quizx_eval::benchmarks(c);

crates/benchmarks/benches/modules/code_distance.rs

@@ -0,0 +1,89 @@
+// Copyright 2026 The PECOS Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+// in compliance with the License. You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software distributed under the License
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+// or implied. See the License for the specific language governing permissions and limitations under
+// the License.
+
+//! Exhaustive code-distance search benchmarks.
+
+use criterion::{Criterion, measurement::Measurement};
+use pecos_core::{Xs, Zs};
+use pecos_qec::{
+    DistanceSearchConfig, StabilizerCode, StabilizerCodeSpec, calculate_distance,
+    find_shortest_logicals,
+};
+use std::hint::black_box;
+
+pub fn benchmarks<M: Measurement>(c: &mut Criterion<M>) {
+    eprintln!(
+        "code-distance benchmark available parallelism: {}",
+        std::thread::available_parallelism().map_or(1, std::num::NonZero::get)
+    );
+
+    let five_qubit = standard_code_spec(&StabilizerCode::five_qubit());
+    let steane = standard_code_spec(&StabilizerCode::steane());
+    let toric_3 = standard_code_spec(&StabilizerCode::toric(3));
+    let color_17 = color_code_17();
+    let config = DistanceSearchConfig::default();
+
+    let mut group = c.benchmark_group("code_distance/calculate_distance");
+    group.sample_size(10);
+    group.bench_function("five_qubit_5_1_3", |b| {
+        b.iter(|| calculate_distance(black_box(&five_qubit), black_box(&config)));
+    });
+    group.bench_function("steane_7_1_3", |b| {
+        b.iter(|| calculate_distance(black_box(&steane), black_box(&config)));
+    });
+    group.bench_function("toric_3_18_2_3", |b| {
+        b.iter(|| calculate_distance(black_box(&toric_3), black_box(&config)));
+    });
+    group.bench_function("color_17_1_5", |b| {
+        b.iter(|| calculate_distance(black_box(&color_17), black_box(&config)));
+    });
+    group.finish();
+
+    let mut group = c.benchmark_group("code_distance/find_shortest_logicals");
+    group.sample_size(10);
+    group.bench_function("color_17_1_5_delta_1", |b| {
+        b.iter(|| find_shortest_logicals(black_box(&color_17), black_box(&config), 1));
+    });
+    group.finish();
+}
+
+fn standard_code_spec(code: &StabilizerCode) -> StabilizerCodeSpec {
+    StabilizerCodeSpec::from_stabilizer_code(code)
+        .expect("standard stabilizer code should have discoverable logicals")
+}
+
+fn color_code_17() -> StabilizerCodeSpec {
+    const SUPPORTS: [&[usize]; 8] = [
+        &[0, 9, 12, 15],
+        &[1, 9, 12, 16],
+        &[2, 11, 13, 14],
+        &[3, 8, 9, 12],
+        &[4, 8, 10, 12, 13, 14, 15, 16],
+        &[5, 10, 11, 13],
+        &[6, 8, 9, 10, 13, 14, 15, 16],
+        &[7, 10, 11, 14],
+    ];
+
+    let mut builder = StabilizerCodeSpec::builder(17);
+    for support in SUPPORTS {
+        builder = builder.check(Xs(support));
+    }
+    for support in SUPPORTS {
+        builder = builder.check(Zs(support));
+    }
+
+    builder
+        .logical_x(Xs(0..17))
+        .logical_z(Zs(0..17))
+        .build()
+        .expect("[[17,1,5]] color code should be valid")
+}