QCborValue: add benchmark for operator[]

In order to test the impact of migration to QASV.

Task-number: QTBUG-101707
Pick-to: 6.6 6.5 6.2
Change-Id: I17f84ca98fc87d89bb4cd6ad98c8a12aecd315ee
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

tests/benchmarks/corelib/CMakeLists.txt

@@ -11,3 +11,4 @@ add_subdirectory(thread)
 add_subdirectory(time)
 add_subdirectory(tools)
 add_subdirectory(plugin)
+add_subdirectory(serialization)

tests/benchmarks/corelib/serialization/CMakeLists.txt

@@ -0,0 +1,4 @@
+# Copyright (C) 2023 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+add_subdirectory(qcborvalue)

tests/benchmarks/corelib/serialization/qcborvalue/CMakeLists.txt

@@ -0,0 +1,10 @@
+# Copyright (C) 2023 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+qt_internal_add_benchmark(tst_bench_qcborvalue
+    SOURCES
+        tst_bench_qcborvalue.cpp
+    LIBRARIES
+        Qt::Core
+        Qt::Test
+)

tests/benchmarks/corelib/serialization/qcborvalue/tst_bench_qcborvalue.cpp

@@ -0,0 +1,72 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#include <QCborMap>
+#include <QCborValue>
+
+#include <QTest>
+
+template <typename Char>
+struct SampleStrings
+{
+    static constexpr char key[] = "hello";
+};
+
+template <>
+struct SampleStrings<char16_t>
+{
+    static constexpr char16_t key[] = u"hello";
+};
+
+template <>
+struct SampleStrings<QChar>
+{
+    static const QChar *const key;
+};
+const QChar *const SampleStrings<QChar>::key =
+        reinterpret_cast<const QChar *>(SampleStrings<char16_t>::key);
+
+template <typename T, typename = void>
+constexpr bool hasValueType = false;
+
+template <typename T>
+constexpr bool hasValueType<T, std::void_t<typename T::value_type>> = true;
+
+class tst_QCborValue : public QObject
+{
+    Q_OBJECT
+private:
+    template <typename Type>
+    void doKeyLookup();
+
+private slots:
+    void keyLookupLatin1() { doKeyLookup<QLatin1StringView>(); }
+    void keyLookupString() { doKeyLookup<QString>(); }
+    void keyLookupConstCharPtr() { doKeyLookup<char>(); };
+};
+
+template <typename Type>
+void tst_QCborValue::doKeyLookup()
+{
+    const QCborMap m{{"hello", "world"}, {1, 2}};
+    const QCborValue v = m;
+
+    if constexpr (hasValueType<Type>) {
+        using Char = std::remove_cv_t<typename Type::value_type>;
+        using Strings = SampleStrings<Char>;
+        const Type s(Strings::key);
+        QBENCHMARK {
+            const QCborValue r = v[s];
+            Q_UNUSED(r);
+        }
+    } else {
+        QBENCHMARK {
+            const QCborValue r = v[SampleStrings<Type>::key];
+            Q_UNUSED(r);
+        }
+    }
+}
+
+QTEST_MAIN(tst_QCborValue)
+
+#include "tst_bench_qcborvalue.moc"