jdk-24/test/hotspot/gtest/utilities/test_powerOfTwo.cpp
Sonia Zaldana Calles 3328b4ecf2 8343700: ceil_log2 should not loop endlessly
Reviewed-by: shade, kbarrett, aph, stuefe
2024-11-19 19:13:09 +00:00

349 lines
12 KiB
C++

/*
* Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
#include "precompiled.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/powerOfTwo.hpp"
#include "unittest.hpp"
#include <limits>
#include <type_traits>
struct StaticTestIsPowerOf2Result {
uint64_t _value;
int _status; // 0: success, > 0 indicates which failure case
constexpr StaticTestIsPowerOf2Result(uint64_t value, int status) :
_value(value), _status(status) {}
};
// Structure copied from test_is_power_of_2 runtime test (below).
template<typename T>
static constexpr StaticTestIsPowerOf2Result static_test_is_power_of_2_aux(T v) {
using Result = StaticTestIsPowerOf2Result;
for ( ; v > 0; v >>= 1) {
if (!is_power_of_2(v)) {
return Result(v, 1);
} else if ((v > 2) && is_power_of_2(T(v - 1))) {
return Result(v, 2);
} else if ((v > 1) && is_power_of_2(T(v + 1))) {
return Result(v, 3);
}
}
return Result(v, 0);
}
template<typename T>
static void static_test_is_power_of_2() {
constexpr StaticTestIsPowerOf2Result result
= static_test_is_power_of_2_aux(max_power_of_2<T>());
EXPECT_EQ(0, result._status)
<< "value = " << result._value << ", status = " << result._status;
}
template <typename T> static void test_is_power_of_2() {
EXPECT_FALSE(is_power_of_2(T(0)));
EXPECT_FALSE(is_power_of_2(~T(0)));
static_assert(!is_power_of_2(T(0)), "");
static_assert(!is_power_of_2(~T(0)), "");
// Should be false regardless of whether T is signed or unsigned.
EXPECT_FALSE(is_power_of_2(std::numeric_limits<T>::min()));
static_assert(!is_power_of_2(std::numeric_limits<T>::min()), "");
// Test true
for (T i = max_power_of_2<T>(); i > 0; i = (i >> 1)) {
EXPECT_TRUE(is_power_of_2(i)) << "value = " << T(i);
}
// Test one less
for (T i = max_power_of_2<T>(); i > 2; i = (i >> 1)) {
EXPECT_FALSE(is_power_of_2(i - 1)) << "value = " << T(i - 1);
}
// Test one more
for (T i = max_power_of_2<T>(); i > 1; i = (i >> 1)) {
EXPECT_FALSE(is_power_of_2(i + 1)) << "value = " << T(i + 1);
}
static_test_is_power_of_2<T>();
}
TEST(power_of_2, is_power_of_2) {
test_is_power_of_2<int8_t>();
test_is_power_of_2<int16_t>();
test_is_power_of_2<int32_t>();
test_is_power_of_2<int64_t>();
test_is_power_of_2<int8_t>();
test_is_power_of_2<int16_t>();
test_is_power_of_2<int32_t>();
test_is_power_of_2<int64_t>();
test_is_power_of_2<jint>();
test_is_power_of_2<jlong>();
}
TEST(power_of_2, exact_log2) {
{
uintptr_t j = 1;
#ifdef _LP64
for (int i = 0; i < 64; i++, j <<= 1) {
#else
for (int i = 0; i < 32; i++, j <<= 1) {
#endif
EXPECT_EQ(i, exact_log2(j));
}
}
{
julong j = 1;
for (int i = 0; i < 64; i++, j <<= 1) {
EXPECT_EQ(i, exact_log2_long(j));
}
}
}
template <typename T> void round_up_power_of_2() {
EXPECT_EQ(round_up_power_of_2(T(1)), T(1)) << "value = " << T(1);
EXPECT_EQ(round_up_power_of_2(T(2)), T(2)) << "value = " << T(2);
EXPECT_EQ(round_up_power_of_2(T(3)), T(4)) << "value = " << T(3);
EXPECT_EQ(round_up_power_of_2(T(4)), T(4)) << "value = " << T(4);
EXPECT_EQ(round_up_power_of_2(T(5)), T(8)) << "value = " << T(5);
EXPECT_EQ(round_up_power_of_2(T(6)), T(8)) << "value = " << T(6);
EXPECT_EQ(round_up_power_of_2(T(7)), T(8)) << "value = " << T(7);
EXPECT_EQ(round_up_power_of_2(T(8)), T(8)) << "value = " << T(8);
EXPECT_EQ(round_up_power_of_2(T(9)), T(16)) << "value = " << T(9);
EXPECT_EQ(round_up_power_of_2(T(10)), T(16)) << "value = " << T(10);
T t_max_pow2 = max_power_of_2<T>();
// round_up(any power of two) should return input
for (T pow2 = T(1); pow2 < t_max_pow2; pow2 *= 2) {
EXPECT_EQ(pow2, round_up_power_of_2(pow2))
<< "value = " << pow2;
}
EXPECT_EQ(round_up_power_of_2(t_max_pow2), t_max_pow2)
<< "value = " << (t_max_pow2);
// For each pow2 gt 2, round_up(pow2 - 1) should return pow2
for (T pow2 = T(4); pow2 < t_max_pow2; pow2 *= 2) {
EXPECT_EQ(pow2, round_up_power_of_2(pow2 - 1))
<< "value = " << pow2;
}
EXPECT_EQ(round_up_power_of_2(t_max_pow2 - 1), t_max_pow2)
<< "value = " << (t_max_pow2 - 1);
}
TEST(power_of_2, round_up_power_of_2) {
round_up_power_of_2<int8_t>();
round_up_power_of_2<int16_t>();
round_up_power_of_2<int32_t>();
round_up_power_of_2<int64_t>();
round_up_power_of_2<uint8_t>();
round_up_power_of_2<uint16_t>();
round_up_power_of_2<uint32_t>();
round_up_power_of_2<uint64_t>();
}
template <typename T> void round_down_power_of_2() {
EXPECT_EQ(round_down_power_of_2(T(1)), T(1)) << "value = " << T(1);
EXPECT_EQ(round_down_power_of_2(T(2)), T(2)) << "value = " << T(2);
EXPECT_EQ(round_down_power_of_2(T(3)), T(2)) << "value = " << T(3);
EXPECT_EQ(round_down_power_of_2(T(4)), T(4)) << "value = " << T(4);
EXPECT_EQ(round_down_power_of_2(T(5)), T(4)) << "value = " << T(5);
EXPECT_EQ(round_down_power_of_2(T(6)), T(4)) << "value = " << T(6);
EXPECT_EQ(round_down_power_of_2(T(7)), T(4)) << "value = " << T(7);
EXPECT_EQ(round_down_power_of_2(T(8)), T(8)) << "value = " << T(8);
EXPECT_EQ(round_down_power_of_2(T(9)), T(8)) << "value = " << T(9);
EXPECT_EQ(round_down_power_of_2(T(10)), T(8)) << "value = " << T(10);
T t_max_pow2 = max_power_of_2<T>();
// For each pow2 >= 2:
// - round_down(pow2) should return pow2
// - round_down(pow2 + 1) should return pow2
// - round_down(pow2 - 1) should return pow2 / 2
for (T pow2 = T(2); pow2 < t_max_pow2; pow2 = pow2 * 2) {
EXPECT_EQ(pow2, round_down_power_of_2(pow2))
<< "value = " << pow2;
EXPECT_EQ(pow2, round_down_power_of_2(pow2 + 1))
<< "value = " << pow2;
EXPECT_EQ(pow2 / 2, round_down_power_of_2(pow2 - 1))
<< "value = " << (pow2 / 2);
}
EXPECT_EQ(round_down_power_of_2(t_max_pow2), t_max_pow2)
<< "value = " << (t_max_pow2);
EXPECT_EQ(round_down_power_of_2(t_max_pow2 + 1), t_max_pow2)
<< "value = " << (t_max_pow2 + 1);
EXPECT_EQ(round_down_power_of_2(t_max_pow2 - 1), t_max_pow2 / 2)
<< "value = " << (t_max_pow2 - 1);
}
TEST(power_of_2, round_down_power_of_2) {
round_down_power_of_2<int8_t>();
round_down_power_of_2<int16_t>();
round_down_power_of_2<int32_t>();
round_down_power_of_2<int64_t>();
round_down_power_of_2<uint8_t>();
round_down_power_of_2<uint16_t>();
round_down_power_of_2<uint32_t>();
round_down_power_of_2<uint64_t>();
}
template <typename T> void next_power_of_2() {
EXPECT_EQ(next_power_of_2(T(0)), T(1)) << "value = " << T(0);
EXPECT_EQ(next_power_of_2(T(1)), T(2)) << "value = " << T(1);
EXPECT_EQ(next_power_of_2(T(2)), T(4)) << "value = " << T(2);
EXPECT_EQ(next_power_of_2(T(3)), T(4)) << "value = " << T(3);
EXPECT_EQ(next_power_of_2(T(4)), T(8)) << "value = " << T(4);
EXPECT_EQ(next_power_of_2(T(5)), T(8)) << "value = " << T(5);
EXPECT_EQ(next_power_of_2(T(6)), T(8)) << "value = " << T(6);
EXPECT_EQ(next_power_of_2(T(7)), T(8)) << "value = " << T(7);
EXPECT_EQ(next_power_of_2(T(8)), T(16)) << "value = " << T(8);
EXPECT_EQ(next_power_of_2(T(9)), T(16)) << "value = " << T(9);
EXPECT_EQ(next_power_of_2(T(10)), T(16)) << "value = " << T(10);
T t_max_pow2 = max_power_of_2<T>();
// next(pow2 - 1) should return pow2
for (T pow2 = T(1); pow2 < t_max_pow2; pow2 = pow2 * 2) {
EXPECT_EQ(pow2, next_power_of_2(pow2 - 1))
<< "value = " << pow2 - 1;
}
EXPECT_EQ(next_power_of_2(t_max_pow2 - 1), t_max_pow2)
<< "value = " << (t_max_pow2 - 1);
// next(pow2) should return pow2 * 2
for (T pow2 = T(1); pow2 < t_max_pow2 / 2; pow2 = pow2 * 2) {
EXPECT_EQ(pow2 * 2, next_power_of_2(pow2))
<< "value = " << pow2;
}
}
TEST(power_of_2, next_power_of_2) {
next_power_of_2<int8_t>();
next_power_of_2<int16_t>();
next_power_of_2<int32_t>();
next_power_of_2<int64_t>();
next_power_of_2<uint8_t>();
next_power_of_2<uint16_t>();
next_power_of_2<uint32_t>();
next_power_of_2<uint64_t>();
}
TEST(power_of_2, max) {
EXPECT_EQ(max_power_of_2<int8_t>(), 0x40);
EXPECT_EQ(max_power_of_2<int16_t>(), 0x4000);
EXPECT_EQ(max_power_of_2<int32_t>(), 0x40000000);
EXPECT_EQ(max_power_of_2<int64_t>(), CONST64(0x4000000000000000));
EXPECT_EQ(max_power_of_2<uint8_t>(), 0x80u);
EXPECT_EQ(max_power_of_2<uint16_t>(), 0x8000u);
EXPECT_EQ(max_power_of_2<uint32_t>(), 0x80000000u);
EXPECT_EQ(max_power_of_2<uint64_t>(), UCONST64(0x8000000000000000));
}
template <typename T, ENABLE_IF(std::is_integral<T>::value)>
void check_log2i_variants_for(T dummy) {
int limit = sizeof(T) * BitsPerByte;
if (std::is_signed<T>::value) {
T min = std::numeric_limits<T>::min();
EXPECT_EQ(limit - 1, log2i_graceful(min));
EXPECT_EQ(limit - 1, log2i_graceful((T)-1));
limit--;
}
{
// Test log2i_graceful handles 0 input
EXPECT_EQ(-1, log2i_graceful(T(0)));
}
{
// Test the all-1s bit patterns
T var = 1;
for (int i = 0; i < limit; i++, var = (var << 1) | 1) {
EXPECT_EQ(i, log2i(var));
}
}
{
// Test the powers of 2 and powers + 1
T var = 1;
for (int i = 0; i < limit; i++, var <<= 1) {
EXPECT_EQ(i, log2i(var));
EXPECT_EQ(i, log2i_graceful(var));
EXPECT_EQ(i, log2i_exact(var));
EXPECT_EQ(i, log2i(var | 1));
}
}
}
TEST(power_of_2, log2i) {
check_log2i_variants_for((uintptr_t)0);
check_log2i_variants_for((intptr_t)0);
check_log2i_variants_for((julong)0);
check_log2i_variants_for((int)0);
check_log2i_variants_for((jint)0);
check_log2i_variants_for((uint)0);
check_log2i_variants_for((jlong)0);
}
template <typename T> void test_ceil_log2() {
EXPECT_EQ(ceil_log2(T(1)), 0) << "value = " << T(1);
EXPECT_EQ(ceil_log2(T(2)), 1) << "value = " << T(2);
EXPECT_EQ(ceil_log2(T(3)), 2) << "value = " << T(3);
EXPECT_EQ(ceil_log2(T(4)), 2) << "value = " << T(4);
EXPECT_EQ(ceil_log2(T(5)), 3) << "value = " << T(5);
EXPECT_EQ(ceil_log2(T(6)), 3) << "value = " << T(6);
EXPECT_EQ(ceil_log2(T(7)), 3) << "value = " << T(7);
EXPECT_EQ(ceil_log2(T(8)), 3) << "value = " << T(8);
EXPECT_EQ(ceil_log2(T(9)), 4) << "value = " << T(9);
EXPECT_EQ(ceil_log2(T(10)), 4) << "value = " << T(10);
// Test max values
if (std::is_unsigned<T>::value) {
EXPECT_EQ(ceil_log2(std::numeric_limits<T>::max()),
(int)(sizeof(T) * 8)) << "value = " << std::numeric_limits<T>::max();
} else {
EXPECT_EQ(ceil_log2(std::numeric_limits<T>::max()),
(int)(sizeof(T) * 8 - 1)) << "value = " << std::numeric_limits<T>::max();
}
}
TEST(power_of_2, ceil_log2) {
test_ceil_log2<int8_t>();
test_ceil_log2<int16_t>();
test_ceil_log2<int32_t>();
test_ceil_log2<int64_t>();
test_ceil_log2<uint8_t>();
test_ceil_log2<uint16_t>();
test_ceil_log2<uint32_t>();
test_ceil_log2<uint64_t>();
}
#ifdef ASSERT
TEST_VM_ASSERT_MSG(power_of_2, ceil_log2_invalid,
".*Invalid value") {
ceil_log2(0);
}
#endif // ASSERT