From 588b653c4024bf2cfc7911ca37df83e5adfd29bb Mon Sep 17 00:00:00 2001
From: tzh476 <tzh476@gmail.com>
Date: Thu, 11 Jun 2026 20:23:13 +0800
Subject: [PATCH] test: add bmi2 bitwise benchmark baseline

Change-Id: Iaa22a3db798903f6852a166ab4a039fd040b959b
---
 examples/automated/CMakeLists.txt             |   6 +
 examples/automated/benchmark_bmi2_bitwise.cpp | 113 ++++++++++++++++++
 2 files changed, 119 insertions(+)
 create mode 100644 examples/automated/benchmark_bmi2_bitwise.cpp

diff --git a/examples/automated/CMakeLists.txt b/examples/automated/CMakeLists.txt
index 5880c2ac0..2fbf257cb 100644
--- a/examples/automated/CMakeLists.txt
+++ b/examples/automated/CMakeLists.txt
@@ -1,3 +1,9 @@
 # @author Tyson Jones
 
 add_all_local_examples()
+
+include(CheckCXXCompilerFlag)
+check_cxx_compiler_flag("-mbmi2" QUEST_COMPILER_SUPPORTS_MBMI2)
+if (QUEST_COMPILER_SUPPORTS_MBMI2)
+  target_compile_options(benchmark_bmi2_bitwise_cpp PRIVATE -mbmi2)
+endif()
diff --git a/examples/automated/benchmark_bmi2_bitwise.cpp b/examples/automated/benchmark_bmi2_bitwise.cpp
new file mode 100644
index 000000000..396f7e2fb
--- /dev/null
+++ b/examples/automated/benchmark_bmi2_bitwise.cpp
@@ -0,0 +1,113 @@
+/** @file
+ * Quick benchmark for BMI2-assisted bit-index helpers.
+ *
+ * @author tzh476
+ */
+
+#include "quest/src/core/bitwise.hpp"
+
+#include <array>
+#include <chrono>
+#include <iomanip>
+#include <iostream>
+#include <limits>
+#include <string>
+#include <vector>
+
+static volatile qindex sinkValue = 0;
+
+template <size_t N>
+qindex makeMask(const std::array<int, N>& indices, qindex pattern) {
+    qindex mask = 0;
+    for (size_t i=0; i<N; i++)
+        if ((pattern >> i) & 1)
+            mask |= QINDEX_ONE << indices[i];
+    return mask;
+}
+
+template <size_t N>
+double benchGet(const std::string& name, const std::array<int, N>& indices, const std::vector<qindex>& inputs, qindex ampMask) {
+    constexpr qindex numIterations = 5000000;
+    constexpr int numReps = 5;
+
+    size_t inputMask = inputs.size() - 1;
+    double best = std::numeric_limits<double>::max();
+
+    for (int r=0; r<numReps; r++) {
+        qindex acc = static_cast<qindex>(0x13579BDF);
+        auto start = std::chrono::steady_clock::now();
+
+        for (qindex i=0; i<numIterations; i++) {
+            qindex n = (inputs[static_cast<size_t>(i) & inputMask] + acc) & ampMask;
+            acc ^= getValueOfBits(n, indices.data(), static_cast<int>(N)) + (i & 7);
+        }
+
+        auto end = std::chrono::steady_clock::now();
+        sinkValue ^= acc;
+
+        double nsPerCall = std::chrono::duration<double, std::nano>(end - start).count() / static_cast<double>(numIterations);
+        best = std::min(best, nsPerCall);
+    }
+
+    std::cout << std::left << std::setw(30) << name << " " << std::fixed << std::setprecision(3) << best << " ns/call\n";
+    return best;
+}
+
+template <size_t N>
+double benchInsert(const std::string& name, const std::array<int, N>& indices, const std::vector<qindex>& inputs, qindex valueMask, qindex insertedMask) {
+    constexpr qindex numIterations = 5000000;
+    constexpr int numReps = 5;
+
+    size_t inputMask = inputs.size() - 1;
+    double best = std::numeric_limits<double>::max();
+
+    for (int r=0; r<numReps; r++) {
+        qindex acc = static_cast<qindex>(0x2468ACE0);
+        auto start = std::chrono::steady_clock::now();
+
+        for (qindex i=0; i<numIterations; i++) {
+            qindex n = (inputs[static_cast<size_t>(i) & inputMask] + acc) & valueMask;
+            acc ^= insertBitsWithMaskedValues(n, indices.data(), static_cast<int>(N), insertedMask) + (i & 15);
+        }
+
+        auto end = std::chrono::steady_clock::now();
+        sinkValue ^= acc;
+
+        double nsPerCall = std::chrono::duration<double, std::nano>(end - start).count() / static_cast<double>(numIterations);
+        best = std::min(best, nsPerCall);
+    }
+
+    std::cout << std::left << std::setw(30) << name << " " << std::fixed << std::setprecision(3) << best << " ns/call\n";
+    return best;
+}
+
+int main() {
+#if defined(QUEST_USE_BMI2_INTRINSICS)
+    std::cout << "BMI2 intrinsics: enabled\n";
+#else
+    std::cout << "BMI2 intrinsics: disabled\n";
+#endif
+
+    std::vector<qindex> inputs(1 << 15);
+    qindex state = static_cast<qindex>(0x123456789ABCDEFULL);
+    for (qindex& input : inputs) {
+        state = state * static_cast<qindex>(0x5851F42D4C957F2DULL) + static_cast<qindex>(0x14057B7EF767814FULL);
+        input = state;
+    }
+
+    qindex nineQubitMask = (QINDEX_ONE << 9) - QINDEX_ONE;
+    const std::array<int, 2> inds2 = {2, 7};
+    const std::array<int, 5> inds5 = {0, 2, 4, 6, 8};
+    const std::array<int, 6> inds6 = {0, 1, 3, 5, 7, 8};
+
+    benchGet("getValueOfBits 2 bits", inds2, inputs, nineQubitMask);
+    benchGet("getValueOfBits 5 bits", inds5, inputs, nineQubitMask);
+    benchGet("getValueOfBits 6 bits", inds6, inputs, nineQubitMask);
+
+    benchInsert("insertBitsWithMask 2 bits", inds2, inputs, (QINDEX_ONE << 7) - QINDEX_ONE, makeMask(inds2, 0b01));
+    benchInsert("insertBitsWithMask 5 bits", inds5, inputs, (QINDEX_ONE << 4) - QINDEX_ONE, makeMask(inds5, 0b10101));
+    benchInsert("insertBitsWithMask 6 bits", inds6, inputs, (QINDEX_ONE << 3) - QINDEX_ONE, makeMask(inds6, 0b101011));
+
+    std::cout << "sink: " << sinkValue << "\n";
+    return 0;
+}