101 lines
3.5 KiB
C++
101 lines
3.5 KiB
C++
/*
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* Copyright (c) 2019, 2020, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#include "precompiled.hpp"
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#include "runtime/os.hpp"
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#include "utilities/population_count.hpp"
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#include "utilities/powerOfTwo.hpp"
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#include "utilities/globalDefinitions.hpp"
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#include "unittest.hpp"
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#include <limits>
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#define BITS_IN_BYTE_ARRAY_SIZE 256
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const uint8_t test_popcnt_bitsInByte[BITS_IN_BYTE_ARRAY_SIZE] = {
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0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
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};
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template <typename T>
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static void sparse() {
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const T max_val = std::numeric_limits<T>::max();
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// Step through the entire input range from a random starting point,
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// verify population_count return values against the lookup table
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// approach used historically
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T step = T(1) << ((sizeof(T) * 8) - 7);
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for (T value = os::random() % step; value < max_val - step; value += step) {
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uint64_t v = (uint64_t)value;
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unsigned lookup = 0u;
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for (unsigned i = 0u; i < sizeof(T); i++) {
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lookup += test_popcnt_bitsInByte[v & 0xff];
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v >>= 8u;
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}
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EXPECT_EQ(lookup, population_count(value))
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<< "value = " << value;
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}
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// Test a few edge cases
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EXPECT_EQ(0u, population_count(T(0u)))
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<< "value = " << 0;
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EXPECT_EQ(1u, population_count(T(1u)))
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<< "value = " << 1;
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EXPECT_EQ(1u, population_count(T(2u)))
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<< "value = " << 2;
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EXPECT_EQ(T(sizeof(T) * BitsPerByte), population_count(max_val))
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<< "value = " << max_val;
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EXPECT_EQ(T(sizeof(T) * BitsPerByte - 1u), population_count(T(max_val - 1u)))
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<< "value = " << (max_val - 1u);
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}
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TEST(population_count, sparse8) {
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sparse<uint8_t>();
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}
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TEST(population_count, sparse16) {
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sparse<uint16_t>();
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}
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TEST(population_count, sparse32) {
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sparse<uint32_t>();
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}
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TEST(population_count, sparse64) {
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sparse<uint64_t>();
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}
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