Tools/TestWebKitAPI/Tests/WTF/SaturatingArithmeticOperations.cpp

/*
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#include "config.h"

#include <limits.h>
#include <limits>
#include <type_traits>
#include <wtf/SaturatingArithmetic.h>

namespace TestWebKitAPI {

TEST(WTF, SaturatingArithmeticAddition)
{
    EXPECT_EQ(0, saturatingSum<int32_t>(0, 0));
    EXPECT_EQ(1, saturatingSum<int32_t>(0, 1));
    EXPECT_EQ(100, saturatingSum<int32_t>(0, 100));
    EXPECT_EQ(150, saturatingSum<int32_t>(100, 50));

    EXPECT_EQ(-1, saturatingSum<int32_t>(0, -1));
    EXPECT_EQ(0, saturatingSum<int32_t>(1, -1));
    EXPECT_EQ(50, saturatingSum<int32_t>(100, -50));
    EXPECT_EQ(-50, saturatingSum<int32_t>(50, -100));

    EXPECT_EQ(INT_MAX - 1, saturatingSum<int32_t>(INT_MAX - 1, 0));
    EXPECT_EQ(INT_MAX, saturatingSum<int32_t>(INT_MAX - 1, 1));
    EXPECT_EQ(INT_MAX, saturatingSum<int32_t>(INT_MAX - 1, 2));
    EXPECT_EQ(INT_MAX - 1, saturatingSum<int32_t>(0, INT_MAX - 1));
    EXPECT_EQ(INT_MAX, saturatingSum<int32_t>(1, INT_MAX - 1));
    EXPECT_EQ(INT_MAX, saturatingSum<int32_t>(2, INT_MAX - 1));
    EXPECT_EQ(INT_MAX, saturatingSum<int32_t>(INT_MAX - 1, INT_MAX - 1));
    EXPECT_EQ(INT_MAX, saturatingSum<int32_t>(INT_MAX, INT_MAX));

    EXPECT_EQ(INT_MIN, saturatingSum<int32_t>(INT_MIN, 0));
    EXPECT_EQ(INT_MIN + 1, saturatingSum<int32_t>(INT_MIN + 1, 0));
    EXPECT_EQ(INT_MIN + 2, saturatingSum<int32_t>(INT_MIN + 1, 1));
    EXPECT_EQ(INT_MIN + 3, saturatingSum<int32_t>(INT_MIN + 1, 2));
    EXPECT_EQ(INT_MIN, saturatingSum<int32_t>(INT_MIN + 1, -1));
    EXPECT_EQ(INT_MIN, saturatingSum<int32_t>(INT_MIN + 1, -2));
    EXPECT_EQ(INT_MIN + 1, saturatingSum<int32_t>(0, INT_MIN + 1));
    EXPECT_EQ(INT_MIN, saturatingSum<int32_t>(-1, INT_MIN + 1));
    EXPECT_EQ(INT_MIN, saturatingSum<int32_t>(-2, INT_MIN + 1));

    EXPECT_EQ(INT_MAX / 2 + 10000, saturatingSum<int32_t>(INT_MAX / 2, 10000));
    EXPECT_EQ(INT_MAX, saturatingSum<int32_t>(INT_MAX / 2 + 1, INT_MAX / 2 + 1));
    EXPECT_EQ(-1, saturatingSum<int32_t>(INT_MIN, INT_MAX));

    EXPECT_EQ(0U, saturatingSum<uint32_t>(0U, 0U));
    EXPECT_EQ(1U, saturatingSum<uint32_t>(0U, 1U));
    EXPECT_EQ(100U, saturatingSum<uint32_t>(0U, 100U));
    EXPECT_EQ(150U, saturatingSum<uint32_t>(100U, 50U));

    EXPECT_EQ(UINT_MAX - 1, saturatingSum<uint32_t>(UINT_MAX - 1U, 0U));
    EXPECT_EQ(UINT_MAX, saturatingSum<uint32_t>(UINT_MAX - 1U, 1U));
    EXPECT_EQ(UINT_MAX, saturatingSum<uint32_t>(UINT_MAX - 1U, 2U));
    EXPECT_EQ(UINT_MAX - 1, saturatingSum<uint32_t>(0U, UINT_MAX - 1U));
    EXPECT_EQ(UINT_MAX, saturatingSum<uint32_t>(1U, UINT_MAX - 1U));
    EXPECT_EQ(UINT_MAX, saturatingSum<uint32_t>(2U, UINT_MAX - 1U));
    EXPECT_EQ(UINT_MAX, saturatingSum<uint32_t>(UINT_MAX - 1U, UINT_MAX - 1U));
    EXPECT_EQ(UINT_MAX, saturatingSum<uint32_t>(UINT_MAX, UINT_MAX));

    EXPECT_EQ(UINT_MAX / 2 + 10000, saturatingSum<uint32_t>(UINT_MAX / 2U, 10000U));
    EXPECT_EQ(UINT_MAX, saturatingSum<uint32_t>(UINT_MAX / 2U, UINT_MAX / 2U + 1U));
    EXPECT_EQ(UINT_MAX, saturatingSum<uint32_t>(UINT_MAX / 2U + 1U, UINT_MAX / 2U + 1U));
    EXPECT_EQ(UINT_MAX, saturatingSum<uint32_t>(UINT_MAX / 3U + 1U, UINT_MAX / 3U, UINT_MAX / 3U));
    EXPECT_EQ(UINT_MAX, saturatingSum<uint32_t>(UINT_MAX / 3U + 1U, UINT_MAX / 3U + 1U, UINT_MAX / 3U + 1U));

    // The variadic (3+ argument) overload must preserve the operand type in its result
    // rather than narrowing to uint32_t, otherwise wide-type sums are silently truncated.
    static_assert(std::same_as<decltype(saturatingSum<uint64_t>(uint64_t { 1 }, uint64_t { 1 }, uint64_t { 1 })), uint64_t>);

    constexpr uint64_t big = static_cast<uint64_t>(UINT_MAX) + 1;
    constexpr uint64_t uint64Max = std::numeric_limits<uint64_t>::max();
    EXPECT_EQ(3 * big, saturatingSum<uint64_t>(big, big, big));
    EXPECT_EQ(big + 3, saturatingSum<uint64_t>(big, uint64_t { 1 }, uint64_t { 2 }));
    EXPECT_EQ(uint64Max, saturatingSum<uint64_t>(uint64Max, uint64_t { 1 }, uint64_t { 1 }));
    EXPECT_EQ(uint64Max, saturatingSum<uint64_t>(uint64Max / 2 + 1, uint64Max / 2 + 1, uint64_t { 1 }));
}

TEST(WTF, SaturatingArithmeticSubtraction)
{
    EXPECT_EQ(0, saturatingDifference<int32_t>(0, 0));
    EXPECT_EQ(-1, saturatingDifference<int32_t>(0, 1));
    EXPECT_EQ(-100, saturatingDifference<int32_t>(0, 100));
    EXPECT_EQ(50, saturatingDifference<int32_t>(100, 50));

    EXPECT_EQ(1, saturatingDifference<int32_t>(0, -1));
    EXPECT_EQ(2, saturatingDifference<int32_t>(1, -1));
    EXPECT_EQ(150, saturatingDifference<int32_t>(100, -50));
    EXPECT_EQ(150, saturatingDifference<int32_t>(50, -100));

    EXPECT_EQ(INT_MAX, saturatingDifference<int32_t>(INT_MAX, 0));
    EXPECT_EQ(INT_MAX - 1, saturatingDifference<int32_t>(INT_MAX, 1));
    EXPECT_EQ(INT_MAX - 1, saturatingDifference<int32_t>(INT_MAX - 1, 0));
    EXPECT_EQ(INT_MAX, saturatingDifference<int32_t>(INT_MAX - 1, -1));
    EXPECT_EQ(INT_MAX, saturatingDifference<int32_t>(INT_MAX - 1, -2));
    EXPECT_EQ(-INT_MAX + 1, saturatingDifference<int32_t>(0, INT_MAX - 1));
    EXPECT_EQ(-INT_MAX, saturatingDifference<int32_t>(-1, INT_MAX - 1));
    EXPECT_EQ(-INT_MAX - 1, saturatingDifference<int32_t>(-2, INT_MAX - 1));
    EXPECT_EQ(-INT_MAX - 1, saturatingDifference<int32_t>(-3, INT_MAX - 1));

    EXPECT_EQ(INT_MIN, saturatingDifference<int32_t>(INT_MIN, 0));
    EXPECT_EQ(INT_MIN + 1, saturatingDifference<int32_t>(INT_MIN + 1, 0));
    EXPECT_EQ(INT_MIN, saturatingDifference<int32_t>(INT_MIN + 1, 1));
    EXPECT_EQ(INT_MIN, saturatingDifference<int32_t>(INT_MIN + 1, 2));

    EXPECT_EQ(0, saturatingDifference<int32_t>(INT_MIN, INT_MIN));
    EXPECT_EQ(0, saturatingDifference<int32_t>(INT_MAX, INT_MAX));
    EXPECT_EQ(INT_MAX, saturatingDifference<int32_t>(INT_MAX, INT_MIN));
}

} // namespace TestWebKitAPI