folly/test/BitsTest.cpp

   1 /*
   2  * Copyright 2012 Facebook, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *   http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 // @author Tudor Bosman (tudorb@fb.com)
  18
  19 #include <gflags/gflags.h>
  20 #include "folly/Bits.h"
  21 #include "folly/Benchmark.h"
  22 #include <gtest/gtest.h>
  23
  24 using namespace folly;
  25
  26 namespace {
  27
  28 template <class INT>
  29 void testFFS() {
  30   EXPECT_EQ(0, findFirstSet(static_cast<INT>(0)));
  31   size_t bits = std::numeric_limits<
  32     typename std::make_unsigned<INT>::type>::digits;
  33   for (size_t i = 0; i < bits; i++) {
  34     INT v = (static_cast<INT>(1) << (bits - 1)) |
  35             (static_cast<INT>(1) << i);
  36     EXPECT_EQ(i+1, findFirstSet(v));
  37   }
  38 }
  39
  40 template <class INT>
  41 void testFLS() {
  42   typedef typename std::make_unsigned<INT>::type UINT;
  43   EXPECT_EQ(0, findLastSet(static_cast<INT>(0)));
  44   size_t bits = std::numeric_limits<UINT>::digits;
  45   for (size_t i = 0; i < bits; i++) {
  46     INT v1 = static_cast<UINT>(1) << i;
  47     EXPECT_EQ(i + 1, findLastSet(v1));
  48
  49     INT v2 = (static_cast<UINT>(1) << i) - 1;
  50     EXPECT_EQ(i, findLastSet(v2));
  51   }
  52 }
  53
  54 }  // namespace
  55
  56 TEST(Bits, FindFirstSet) {
  57   testFFS<char>();
  58   testFFS<signed char>();
  59   testFFS<unsigned char>();
  60   testFFS<short>();
  61   testFFS<unsigned short>();
  62   testFFS<int>();
  63   testFFS<unsigned int>();
  64   testFFS<long>();
  65   testFFS<unsigned long>();
  66   testFFS<long long>();
  67   testFFS<unsigned long long>();
  68 }
  69
  70 TEST(Bits, FindLastSet) {
  71   testFLS<char>();
  72   testFLS<signed char>();
  73   testFLS<unsigned char>();
  74   testFLS<short>();
  75   testFLS<unsigned short>();
  76   testFLS<int>();
  77   testFLS<unsigned int>();
  78   testFLS<long>();
  79   testFLS<unsigned long>();
  80   testFLS<long long>();
  81   testFLS<unsigned long long>();
  82 }
  83
  84 #define testPowTwo(nextPowTwoFunc) {                              \
  85   EXPECT_EQ(1, nextPowTwoFunc(0u));                               \
  86   EXPECT_EQ(1, nextPowTwoFunc(1u));                               \
  87   EXPECT_EQ(2, nextPowTwoFunc(2u));                               \
  88   EXPECT_EQ(4, nextPowTwoFunc(3u));                               \
  89   EXPECT_EQ(4, nextPowTwoFunc(4u));                               \
  90   EXPECT_EQ(8, nextPowTwoFunc(5u));                               \
  91   EXPECT_EQ(8, nextPowTwoFunc(6u));                               \
  92   EXPECT_EQ(8, nextPowTwoFunc(7u));                               \
  93   EXPECT_EQ(8, nextPowTwoFunc(8u));                               \
  94   EXPECT_EQ(16, nextPowTwoFunc(9u));                              \
  95   EXPECT_EQ(16, nextPowTwoFunc(13u));                             \
  96   EXPECT_EQ(16, nextPowTwoFunc(16u));                             \
  97   EXPECT_EQ(512, nextPowTwoFunc(510u));                           \
  98   EXPECT_EQ(512, nextPowTwoFunc(511u));                           \
  99   EXPECT_EQ(512, nextPowTwoFunc(512u));                           \
 100   EXPECT_EQ(1024, nextPowTwoFunc(513u));                          \
 101   EXPECT_EQ(1024, nextPowTwoFunc(777u));                          \
 102   EXPECT_EQ(1ul << 31, nextPowTwoFunc((1ul << 31) - 1));          \
 103   EXPECT_EQ(1ul << 32, nextPowTwoFunc((1ul << 32) - 1));          \
 104   EXPECT_EQ(1ull << 63, nextPowTwoFunc((1ull << 62) + 1));        \
 105 }
 106
 107
 108 TEST(Bits, nextPowTwoClz) {
 109   testPowTwo(nextPowTwo);
 110 }
 111
 112 BENCHMARK(nextPowTwoClz, iters) {
 113   for (unsigned long i = 0; i < iters; ++i) {
 114     auto x = folly::nextPowTwo(iters);
 115     folly::doNotOptimizeAway(x);
 116   }
 117 }
 118
 119 TEST(Bits, isPowTwo) {
 120   EXPECT_FALSE(isPowTwo(0u));
 121   EXPECT_TRUE(isPowTwo(1ul));
 122   EXPECT_TRUE(isPowTwo(2ull));
 123   EXPECT_FALSE(isPowTwo(3ul));
 124   EXPECT_TRUE(isPowTwo(4ul));
 125   EXPECT_FALSE(isPowTwo(5ul));
 126   EXPECT_TRUE(isPowTwo(8ul));
 127   EXPECT_FALSE(isPowTwo(15u));
 128   EXPECT_TRUE(isPowTwo(16u));
 129   EXPECT_FALSE(isPowTwo(17u));
 130   EXPECT_FALSE(isPowTwo(511ul));
 131   EXPECT_TRUE(isPowTwo(512ul));
 132   EXPECT_FALSE(isPowTwo(513ul));
 133   EXPECT_FALSE(isPowTwo((1ul<<31) - 1));
 134   EXPECT_TRUE(isPowTwo(1ul<<31));
 135   EXPECT_FALSE(isPowTwo((1ul<<31) + 1));
 136   EXPECT_FALSE(isPowTwo((1ull<<63) - 1));
 137   EXPECT_TRUE(isPowTwo(1ull<<63));
 138   EXPECT_FALSE(isPowTwo((1ull<<63) + 1));
 139 }
 140
 141 BENCHMARK_DRAW_LINE();
 142 BENCHMARK(isPowTwo, iters) {
 143   bool b;
 144   for (unsigned long i = 0; i < iters; ++i) {
 145     b = folly::isPowTwo(i);
 146     folly::doNotOptimizeAway(b);
 147   }
 148 }
 149
 150 TEST(Bits, popcount) {
 151   EXPECT_EQ(0, popcount(0U));
 152   EXPECT_EQ(1, popcount(1U));
 153   EXPECT_EQ(32, popcount(uint32_t(-1)));
 154   EXPECT_EQ(64, popcount(uint64_t(-1)));
 155 }
 156
 157 int main(int argc, char** argv) {
 158   testing::InitGoogleTest(&argc, argv);
 159   google::ParseCommandLineFlags(&argc, &argv, true);
 160   auto ret = RUN_ALL_TESTS();
 161   if (!ret && FLAGS_benchmark) {
 162     folly::runBenchmarks();
 163   }
 164   return ret;
 165 }
 166
 167 /*
 168 Benchmarks run on dual Xeon X5650's @ 2.67GHz w/hyperthreading enabled
 169   (12 physical cores, 12 MB cache, 72 GB RAM)
 170
 171 Benchmark                               Iters   Total t    t/iter iter/sec
 172 ------------------------------------------------------------------------------
 173 *       nextPowTwoClz                 1000000  1.659 ms  1.659 ns  574.8 M
 174 */