ladybird/Tests/AK/TestHashFunctions.cpp

/*
 * Copyright (c) 2020, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibTest/TestCase.h>

#include <AK/HashFunctions.h>
#include <AK/Types.h>

TEST_CASE(u32_hash)
{
    static_assert(u32_hash(42) == 142593372u);
    static_assert(u32_hash(0) == 0u);
}

TEST_CASE(pair_int_hash)
{
    static_assert(pair_int_hash(42, 17) == 1110885963u);
    static_assert(pair_int_hash(0, 0) == 0u);
}

TEST_CASE(u64_hash)
{
    static_assert(u64_hash(42) == 2386713036u);
    static_assert(u64_hash(0) == 0u);
}

TEST_CASE(ptr_hash)
{
    // These tests are not static_asserts because the values are
    // different and the goal is to bind the behavior.
    if constexpr (sizeof(FlatPtr) == 8) {
        EXPECT_EQ(ptr_hash(FlatPtr(42)), 2386713036u);
        EXPECT_EQ(ptr_hash(FlatPtr(0)), 0u);

        EXPECT_EQ(ptr_hash(reinterpret_cast<void const*>(42)), 2386713036u);
        EXPECT_EQ(ptr_hash(reinterpret_cast<void const*>(0)), 0u);
    } else {
        EXPECT_EQ(ptr_hash(FlatPtr(42)), 142593372u);
        EXPECT_EQ(ptr_hash(FlatPtr(0)), 0u);

        EXPECT_EQ(ptr_hash(reinterpret_cast<void const*>(42)), 142593372u);
        EXPECT_EQ(ptr_hash(reinterpret_cast<void const*>(0)), 0u);
    }
}

TEST_CASE(constexpr_ptr_hash)
{
    // This test does not check the result because the goal is just to
    // ensure the function can be executed in a constexpr context. The
    // "ptr_hash" test binds the result.
    static_assert(ptr_hash(FlatPtr(42)));
}

template<typename HashFunction>
requires(IsCallableWithArguments<HashFunction, unsigned, u64>)
static void run_benchmark(HashFunction hash_function)
{
    for (size_t i = 0; i < 1'000'000; ++i) {
        auto a = hash_function(i);
        AK::taint_for_optimizer(a);
        auto b = hash_function(i);
        AK::taint_for_optimizer(b);
        EXPECT_EQ(a, b);
    }
}

BENCHMARK_CASE(deterministic_hash)
{
    run_benchmark(u64_hash);
}